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1
Rebelo, Jorge Manuel Baeta Simões. "Biosynthesis and function of biological pteridines structural studies on two molybdopterin containing aldehyde oxido-reductases, from Desulfovibrio desulfuricans ATCC 27774 and from Desulfovibrio gigas, and the GTP cyclohydrolase I on E. coli, responsible for the first step of the tetrahydropterin biosynthesis /." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972340319.
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Guschin, Dmitrii. "Chemische Modifizierung von Pyranopterinen und deren Metallkomplexe strukturelle Modelle für Zentren in Metalloenzymen /." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=967843537.
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Ekwall, Olov. "Pteridine dependent hydroxylases as autoantigens in autoimmune polyendocrine syndrome type 1." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2001. http://publications.uu.se/theses/91-554-4941-7/.
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Chatelet, Pascal. "Ptéridines non conjuguées et infections neuro-méningées." Lille 2, 1990. http://www.theses.fr/1990LIL2M349.
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Graham, Gordon W. "A study of biochemical genetic abnormalities associated with purine and pteridine metabolism." Thesis, University of Glasgow, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301808.
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Barrack, Keri L. "Structural examination of trypanosomatid tubulin-binding cofactors and pteridine reductase 1 inhibition." Thesis, University of Dundee, 2013. https://discovery.dundee.ac.uk/en/studentTheses/73141a09-d8c2-4410-8884-3b3d80d1be00.
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Trypanosomatid parasites are the causative agents of neglected tropical diseases for which current therapies are inadequate. As primitive eukaryotic organisms, they also represent a useful model system to investigate fundamental cellular biology while studies of potential drug targets endeavour to develop new drug molecules. Aspects of both of these areas are explored in this thesis. Microtubules are polymers of tubulin and are essential in eukaryotes for cell division, motility and maintenance of cell morphology. Five tubulin-binding cofactors (TBC, named A-E) are proteins implicated in the folding, polymerisation and processing of tubulin, the major component of the trypanosomatid cytoskeleton. At the initiation of this study, there was no structural information available for any trypanosomatid TBC. We therefore sought to investigate these proteins by X-ray crystallography and assess their potential tubulin-interaction capabilities to support the current functional model. The crystal structure of tubulin-binding cofactor A (TBCA) from Leishmania major is presented, determined using diffraction data to 1.9 Å resolution. Prior to tubulin polymerisation, TBCA forms a complex with ß-tubulin in the pathway to aß-tubulin heterodimerisation. It maintains a soluble pool of ß-tubulin and can prevent premature polymerisation. This is a short helical protein, similar in structure to published homologues. The similarities and some distinct local features that may impact on ß-tubulin binding are discussed. In particular, the surface properties of a prominent bend in the helix bundle represents an area that may be capable of interacting with its tubulin partner. Tubulin-binding cofactor C (TBCC) is implicated in stimulating the hydrolysis of GTP bound to ß-tubulin prior to release of the assembly-competent aß-tubulin heterodimer from a supercomplex between TBCC, TBCD, TBCE and both tubulin subunits. Full-length recombinant Trypanosoma brucei and Leishmania major tubulin-binding TBCC were degraded and crystallisation could not be achieved. However, crystals of a truncated TBCC construct were obtained. Despite efforts to optimise crystallisation and diffraction data, the structure was not solved for inclusion in this thesis. Instead, homologous structures were analysed and a potential tubulin interaction site is suggested based on the proposed GTPase-stimulating activity of TBCC and the similarity with the human protein, Retinitis Pigmentosa 2 (RP2), predicted to contain a domain with similar fold. Progress towards the soluble recombinant expression of the other cofactors also lays the foundation for future investigations into trypanosomatid TBC structure and function. Pteridine reductase 1 (PTR1), an enzyme unique to trypanosomatids, is the subject of Part II of this thesis. PTR1 is a broad-spectrum NADPH-dependent reductase, catalysing the two-stage reduction of biopterin to dihydrobiopterin and tetrahydrobiopterin and that of folate to dihydrofolate and tetrahydrofolate. As such, it can provide a bypass mechanism for the reduction of folates, reducing the therapeutic action of traditional antifolate molecules in these organisms. Inhibition of PTR1 is therefore desirable from a drug discovery viewpoint. The crystal structure of Leishmania donovani PTR1 was determined using data extending to 2.5 Å resolution with a view to generating ligand-complex structures and providing a model for inhibitor design. This structure was found to contain a disordered active site, with several loop regions not modelled or relocated. A sulfate molecule from the crystallisation mixture binds in the cofactor phosphate binding-site and the sequential binding of cofactor before substrate or inhibitor can not occur. Although this crystal form was considered unsuitable for further studies, it provides the only structure of PTR1 in the absence of cofactor. With an established crystallisation protocol, Trypanosoma brucei PTR1 then forms the basis of a collaborative investigation of over 100 novel potential inhibitory molecules. Kinetic evaluation, isothermal titration calorimetry (ITC) and co-crystallisation were applied to generate ligand-binding profiles of pyrrolopyrimidine derivatives. Several interesting binding features were identified from the 24 ligand complex structures obtained. These include the discovery of two covalent inhibitors, confirming the reactivity of a non-conserved active site cysteine, and molecules that are able to bind simultaneously at two locations within the active site pocket, exploiting hydrogen-bonding interactions with key catalytic and other nearby residues. The thermodynamic binding profiles of seven inhibitors also provide insight into the enthalpic and entropic contributions to ligand binding. We assessed the suitability of ITC for this system and while a high attrition rate was observed, chemical substitutions were able to enhance the binding entropy. These studies have strengthened our understanding of the structure-activity relationship between PTR1 and inhibitors, offering opportunities to develop new molecules that focus on increasing the potency generated by favourable enthalpy alongside improving the drug-like properties.
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Luba, James. "Studies of Leishmania major Pteridine Reductase 1, a Novel Short Chain Dehydrogenase." eScholarship@UMMS, 1997. https://escholarship.umassmed.edu/gsbs_diss/45.
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Pteridine reductase 1 (PTR1) is an NADPH dependent reductase that catalyzes the reduction of several pterins and folates. The gene encoding this enzyme was originally identified in Leishmania based on its ability to provide resistance to the drug methotrexate (MTX). The DNA and amino acid sequences are known, and overproducing strains of Escherichia coli are available. PTR1 has been previously shown to be required for the salvage of oxidized pteridines (folate, biopterin, and others). Since Leishmaniaare folate and pterin auxotrophes, PTR1 is a possible target for novel anti-folate drugs for the treatment of leishmaniasis.
PTR1 catalyzes the transfer of hydride from NADPH to the 2-amino-4-oxo-pteridine ring system yielding 7, 8-dihydropteridines, and to the pteridine ring system of 7, 8-dihydropteridines yielding 5,6, 7, 8-tetrahydropteridines. PTR1 shows a pH dependent substrate specificity. At pH 4.6 the specific activity of PTR1 is highest with pterins, while at pH 6.0 the specific activity of PTR1 was highest with folates.
The sequence of PTR1 is only 20-30% homologous to the sequences of members of the short chain dehydrogenase/reductase enzyme family. Although this is typical for members of this enzyme family, it does not allow for unambiguous classification in this family. In fact, when the DNA sequence of PTR1was first determined, PTR1 was classified as an aldoketo reductase. To classify PTR1 definitively, further biochemical characterization was required. To provide this information, the work described here was undertaken: (i) the stereochemical and kinetic course of PTR1 was determined; (ii) residues important in catalysis and ligand binding were identified; and (iii) conditions for the crystallization of PTR1 were developed.
The stereochemistry of hydride transfer
The use of [3H]-folate, showed that the ultimate product of PTR1 was 5, 6, 7, 8-tetrahydrofolate. 4R-[3H]-NADPH and 4S-[3H]-NADPH were synthesized enzymatically and used as the cofactor for the reduction of folate. PTR1 was coupled to thymidylate synthase (TS), and tritium from 4S-[3H]-NADPH was transferred to thymidylate. Therefore, the pro-S hydride of NADPH was transferred to the si face of dihydrofolate (DHF; see figure I-1). The transfer of the pro-Shydride indicates that PTR1 is a B-side dehydrogenase which is consistent with its membership in the short chain dehydrogenase (SDR) family.
The kinetic mechanism of PTR1
When NADPH was varied at several fixed concentrations of folate (and vice-versa) V/K (Vmax/KM) showed a dependence upon concentration of the fixed substrate. This is consistent with a ternary complex mechanism, in contrast to a substituted enzyme mechanism that exhibits no dependence of V/K on fixed substrate. Product inhibition patterns using NADP+ and 5-deazatetrahydrofolate (5dTHF, a stable product analog) were consistent with an ordered ternary complex mechanism in which NADPH binds first and NADP+ dissociates last. However, an enzyme-DHF binary complex was detected by fluorescence. Isotope partitioning experiments showed that the enzyme-DHF binary complex was not catalytically competent whereas the enzyme-NADPH complex was. Measurement of the tritium isotope effect on V/K (T(V/K)) at high and low dihydrofolate confirmed that PTR1 proceeds via a steady state ordered mechanism. Rapid quench analysis showed that dihydrofolate was a transient intermediate during the reduction of folate to tetrahydrofolate and that folate reduction is biphasic.
Catalytic Residues of PTR1
The amino acid sequences of dihydropteridine reductase and 3-α, 20-β, hydroxy steroid dehydrogenase were aligned to that of PTR1. Based on the results of the alignment, site directed mutagenesis was used to investigate the role of specific residues in the catalytic cycle of PTR1. Variant enzymes were screened based on their ability to rescue a dihydrofolate reductase (DHFR) deficient strain of E. coli. Selected PTR1 variants (some complementing and some non-complementing) were purified and further characterized. Tyrosine 193 of the wild type enzyme was found to be involved in the reduction of pteridines, but not in the reduction of 7, 8-dihydropteridines, and eliminated the substrate inhibition of 7, 8-dihydropteridines observed with the wild type enzyme. Both PTR1(K197Q) and PTR1(Y193F/K197Q) had decreased activity for all substrates and low affinity for NADPH. In contrast to the wild type enzyme, NADPH displayed substrate inhibition towards PTR1(K197Q). All PTR1(D180) variants that were purified were inactive except for PTR1(D180C), which showed 2.5% of wild type activity with DHF. The binary complexes of PTR1(D180A) and PTR1(D180S) with NADPH showed a decrease in affinity for folate. Based on the kinetic properties of the PTR1 variants, roles for Y193, K197, and D180 are proposed. In conjunction with D180, Y193 acts as a proton donor to N8 of folate. K197 forms hydrogen bonds with NADPH in the active site and lowers the pKaof Y193. D180 participates in the protonation of N8 of folate and N5 of DHF.
Crystallization of PTR1 and PTR1-ligand complexes
The crystallization of PTR1 from L. major and L. tarentolea as unliganded and as binary and ternary complexes was attempted. Several crystal forms were obtained including L. major PTR1-NADPH-MTX crystals that diffracted to ~ 3.2 Å resolution. It was not possible to collect a full data set of any of the crystals. At their current stage, none of the crystal forms is suitable for structural work.
8
Morin, Eric. "La néoptérine : aspects analytiques et physio-pathologiques." Paris 5, 1995. http://www.theses.fr/1995PA05P038.
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Vargas, Lowman Aidamalia. "Les bases génétiques de la pigmentation dans les embryons de punaise d'eau." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEN042/document.
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Le but de ce doctorat était de comprendre les bases génétiques de la diversification de la pigmentation extra-oculaire chez les embryons des Gerromorphes. La plupart des punaises semi-aquatiques présentent une variabilité de pattern de couleur jaune ou/et rouge dans les pattes et les antennes au stade embryonnaire. La couleur rouge observée dans les appendices étant similaire à celle présente dans les yeux, nous avons émis l'hypothèse que les couleurs extra-oculaires pouvaient être produites par la co-option des voies de synthèse des pigments des yeux. Nous avons d'abord déterminé l'histoire évolutive de ce trait à partir de sa présence ou de son absence dans les embryons de 34 espèces. Grâce à l'analyse génétique par interférence ARN et hybridation in situ, nous avons identifié les voies impliquées dans la pigmentation des yeux et des organes extra-oculaires dans l'espèce Limnogonus franciscanus. Nous avons ensuite testé par interférence ARN et hybridation in situ trois gènes de la voie ptéridine dans cinq autres espèces de Gerromorphes présentant des colorations extra-oculaires différentes. Les résultats suggèrent que la même voie a été recrutée une seule fois pour produire la diversité de pattern. De plus, grâce à une analyse chimique par ultra-chromatographie couplée à de la spectrométrie de masse, nous avons identifié que la xanthopterin et l’erythropterin sont les deux pigments responsables de la couleur chez différentes espèces. Nous nous sommes aussi demandé comment le recrutement d'une seule et même voie conservée pouvait produire une telle diversité de pattern. En utilisant la technologie de transcriptomique du RNA-seq, nous avons identifié 167 facteurs de transcription co-exprimés dans les yeux, les antennes et les pattes des embryons de Limnogonus franciscanus. Ces protéines pourraient intervenir dans la régulation des gènes impliqués dans la formation des patterns de couleur embryonnaire. Nous avons initié un crible ARNi de ces facteurs de transcription. En conclusion, la pigmentation des punaises semi-aquatiques au stade embryonnaire est un bon modèle pour comprendre la co-option des voies génétiques et la question sous-jacente de la façon dont une voie conservée pourrait être réglementée pour produire divers phénotypes<br>The principal aim of this doctoral thesis was to understand the genetic basis for the diversification of the extra-ocular pigmentation in Gerromorpha embryos. Most of the semi-aquatic bugs develop a variability of yellow or red colours patterns in legs and antennas during the embryonic stage. Since the red colour in appendages was similar to the one present in eyes, we hypothesized that the extra-ocular colours could be produced by the co-option of the eye pigments biosynthesis pathway. First we inferred the evolutionary history of this trait based on its presence or absence in embryos of 34 species. We found that the ancestral state of the trait in Gerromorpha was yellow and that six independent lineages evolved bright red colour, while two lineages lost the colour. Using RNAi and in situ hybridisation on homologous genes from the pteridine and ommochrome biosynthesis pathways, we described the genetic pathway involved in the production of pigments in eyes and extra-ocular tissues in Limnogonus franciscanus embryos. After that, we performed a screening of three genes from this pathway in five other species with different extra-ocular colours and patterns. We discovered that the same pathway was recruited once to produce the diversity of patterns in Gerromorpha. Furthermore, we identified by UPLC-HRMS that xanthopterin and erythropterin pigments produce the variability of colours and patterns in different species. Our next step aimed to understand how the recruitment of a conserved pathway could produce this striking diversity of colour patterns. Using RNA-Seq technology and bioinformatics tools, we identified 167 transcription factors that are co-expressed in eyes, antennas and legs of embryos in Limnogonus franciscanus. These proteins might be involved in the regulation of genes responsible for the different colour patterns. We have started an RNAi screen of these transcription factors. This project is still ongoing but in this thesis I will present the preliminary results and conclusions.In conclusion, the pigmentation of semi-aquatic bugs during the embryonic stage is a good model to understand the co-option of pre-existing genetic pathways and underlying the question of how a conserved pathway could be regulated to produce diverse morphological phenotypes
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Martini, Viviane Paula. "DETERMINAÇÃO E ESTUDOS DE ESTRUTURAS DE COMPLEXOS ENZIMALIGANTES RELEVANTES À BIOLOGIA DAS PTERIDINAS EM PARASITAS: BASE PARA O DESENVOLVIMENTO RACIONAL DE DROGAS TERAPÊUTICAS CONTRA DOENÇA DO SONO." UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2007. http://tede2.uepg.br/jspui/handle/prefix/2124.
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Previous issue date: 2007-03-06<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>The enzymes dihydrofolate reductase-thymidylate synthase (DHFR-TS) and pteridine reductase (PTR) are involved in the pterin/folate dependent metabolism; together they
represent an important target for chemotherapy of parasitic leishmanias and trypanosomes. Xray crystallography was used to elucidate accurately the structure of the PTR1 enzyme from
Trypanosoma brucei in complex with inhibitors which are analogous to the substrate. The ligands assayed for crystallization were the substrate folate and the inhibitors
melamine, 6-thioguanine, WSG1012, WSG1034, WSG3065, WSG3066 and WSG3067. Of these, four yielded crystals with diffraction patterns sufficient for a complete dataset.
WSG3065 (later revealing the lack of the ligand), WSG3066 and WSG3067 are three of the several structures presented in this work which came from the cited crystallization assays;
added to these are the refined structures complexed with triamterene and cyromazine, proceeded from two other datasets already available. The datasets were processed with the programs Mosflm / Scala and Xds / Xscale, the structures were refined using the programs CNS and Refmac5 and validated with the programs Procheck, Whatcheck, Sfcheck and ValidationPDB. All refined structures belong to the space group P21 with unit cells around a = 79, b = 90, c = 82, b = 115, 4 monomers each of 268 residues per asymmetric unit
and complex active sites. Besides the inhibiting ligands (except WSG3065) present in the structure, other ligands were found either near or outside the active site: dithiothreitol, glycerol, ethylene glycol, sodium and acetate ions. Analyses on the ligand positions and corresponding interactions with the protein were carried out to understand modes of inhibition and to guide the design or the discovery of new compounds which are potent, but selective to
the parasitic enzyme, inhibitors. Thereby, initial docking studies were performed aiming at identifying new molecules or lead compounds with inhibitory capabilities.<br>As enzimas dihidrofolato redutase-timidilato sintase (DHFR-TS) e pteridina redutase (PTR) estão envolvidas no metabolismo pterina/folato dependente; juntas, representam um importante alvo para a quimioterapia de leishmanias e tripanossomas parasitas. A Cristalografia por Raios X foi utilizada para elucidar acuradamente a estrutura da enzima
PTR1 de Trypanosoma brucei complexada com inibidores que são análogos ao substrato. Os ligantes ensaiados para cristalização foram o substrato folato e os inibidores
melamina, 6-tioguanina, WSG1012, WSG1034, WSG3065, WSG3066 e WSG3067. Destes, quatro forneceram cristais com padrões de difração suficientes para um conjunto de dados
completo. WSG3065 (mais tarde revelando ausência do ligante), WSG3066 e WSG3067 são três das estruturas apresentadas neste trabalho derivadas dos ensaios de cristalização citados; somadas a estas estão as estruturas refinadas dos complexos com triantereno e ciromazina,
provenientes de dois outros conjuntos de dados anteriormente disponíveis. Os conjuntos de dados foram processados com os programas Mosflm / Scala e Xds / Xscale, as estruturas refinadas usando-se os programas CNS e Refmac5 e validadas com os programas Procheck,
Whatcheck, Sfcheck e ValidationPDB. Todas as estruturas refinadas apresentaram grupo espacial P21 com celas unitárias aproximadas a = 79 = 90, c = 82 , b = 115, 4
monômeros de 268 resíduos cada por unidade assimétrica e sítios ativos complexos. Além dos ligantes inibidores presentes nas estruturas (exceto WSG3065), outros ligantes foram
encontrados próximos ou fora do sítio ativo: ditiotreitol, glicerol, etilenoglicol, íons sódio e íons acetato. Análises das posições dos ligantes inibidores e correspondentes interações com a proteína foram realizadas a fim de se entender modos de inibição e, em particular, assistir ao planejamento ou à descoberta de novos compostos que sejam inibidores potentes, mas seletivos, para a enzima parasitária. Assim, estudos iniciais de atracagem (docking) foram realizados visando identificar novas moléculas ou arcabouços com capacidades inibitórias.
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McElwee, M. J. "Studies on the development of fungal pathogens (Ascochyta pteridis and Phoma aquilina) as agents of biological control of bracken (Pteridium aquilinum (L) Kuhn)." Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382396.
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Attree, S. M. "Properties of Pteridium protoplasts." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378009.
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Koch, Klemens Eduard. "Ueber strukturelle Zusammenhänge zwischen Blausäure und natürlichen Purinen und Pteridinen /." Zürich : Juris, 1992. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=9968.
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Jatoba, Luciana de Jesus. "Alelopatia em Pteridium arachnoideum (Kaulf.) Maxon. (Dennstaedtiaceae)." Universidade Federal de São Carlos, 2016. https://repositorio.ufscar.br/handle/ufscar/7979.
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Previous issue date: 2016-03-18<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>Pteridium plants are ferns (monilopytes) distributed all around the globe. These plants are considered problem species as they invade recently abandoned or burned areas, and areas under anthropogenic impacts. In Brazil, Pteridium arachnoideum (Kaulf.) Maxon. has become an important problem species at the Cerrado (Tropical Savanna) and Atlantic Forest biomes. To understand the mechanisms underlying invasive plants success are one of the greatest challenges of the last decades. Among the interaction that can influence this success, we find allelopathy. However, untill now we have few evidences for this phenomenon on these plants, especially from the isolation and indentification of secondary metabolites with activities related to allelopathy. Therefore, the present work aimed to evaluate the allelopathy role by direct phytotoxicity and abiotic changes in Pteridium arachnoideum (Kaulf.) Maxon. dominance in the areas it invades. To do so, the bioguided phytochemical study of this plant tissues and litter was performed, as well as the evaluation of the phytotoxic activity of phenolic
compounds present in its litter and of its isolated and identified secondary metabolite against the early development of sesame, verifying the presence of this compound in the soil, its quantification, and evaluation of its interactions with physical and chemical soil characteristics. The phytochemical study led to the isolation and identification of a majoritarian compound in the plants green fronds and litter, the proanthocianidin selligueian A. This is the first time this compound is described for P. arachnoideum, as well as for the Dennstaediaceae family. Selligueain A showed phytotoxic activity against wheat coleoptiles elongation, with inhibitory activity over 71%, and IC50 of 0.69 mM. The poliphenols enriched fraction extracted from P. arachnoideum litter exert inhibitory activity against the early development of bioindicators species, native and invasive species of the Cerrado biome, specially over the development of these seedlings roots, besides activity against the metaxylem cells of sesame, and against chlorophyll content of sesame and the native weed Setaria parviflora. The allelopathic potential of the main poliphenolic compound of P. arachnoideum, selligueain A, was also evaluated against the early growth of sesame seedlings, promoting root and shoot growth in all the concentrations tested. Sesame seedlings grown in the presence of selligueain A showed smaller metaxylem cells when compared to the control, in the concentrations of 0.3 mM e 1 mM, with 50.82% inhibition in the greatest concentration and IC50 value of 0.98 mM. There was no activity of selligueain A against chlorophyll content of these seedlings. Analyses of extracts of soil collect under a P. arachnoideum patches pointed to the presence of selligueain A as major compound in soil solution, and, therefore, as a putative allelochemical produced by this plant. The concentration observed for this compound in the soil raged between 0.02 and 0.65 mM. According to allelopathic potential results, this concentration rage is sufficient to act over cooccurring plant species, promoting P. arachnoideum dominance. The presence of P. arachnoideum in Cerrado areas alters the chemical conditions of the soil, especially regarding N and Al, when compared to the presence of U. decumbens. Additionally, Al concentration is correlated to litter mass and to selligueain A concentration at the sites sampled. These results corroborates the hypothesis of allelopathy as a dominance mechanism of this plant in the areas where it occurs, with the first report of an allelochemical for a Pteridium species, by direct phytotoxic activity as well as by controlling Al concentration at those areas.<br>Plantas do gênero Pteridium são samambaias (monilófitas) e estão distribuídas em todo mundo. São consideradas espécies problemas pois invadem áreas recentemente queimadas, abandonadas ou sob impacto antrópico. No Brasil, Pteridium arachnoideum (Kaulf.) Maxon. apresenta-se como uma importante espécie problema do Cerrado e da Mata Atlântica. Compreender os mecanismos que governam o sucesso de plantas com comportamento invasor tem se mostrado um dos maiores desafios das últimas décadas. Dentre as interações que podem influenciar este sucesso está a alelopatia. No entanto, poucas são as evidências apresentadas até então para este fenômeno, especialmente a partir do isolamento e identificação de substâncias do metabolismo secundário destas plantas. Assim, o objetivo deste trabalho foi avaliar o papel da alelopatia por fitotoxicidade direta e alterações abióticas na dominância de P. arachnoideum nas áreas em que ocorre. Para isso, foi realizado estudo fitoquímico biodirigido de diferentes órgãos e serrapilheira desta planta, avaliação da atividade fitotóxica dos polifenóis e do metabólito secundário isolado e identificado sobre o desenvolvimento inicial da espécie bioindicadora gergelim, identificação da presença deste composto no solo, sua quantificação e avaliação de sua interação com características físicoquímicas do solo. O estudo fitoquímico levou ao isolamento de um composto majoritário presente em suas frondes verdes e serrapilheira desta planta, a proantocianidina selligueina A. Esta é a primeira vez que este composto é descrito para P. arachnoideum, assim como para a família Dennstaediaceae. A selligueina A apresentou atividade fitotóxica sobre o alongamento de coleóptilos de trigo, com atividade inibitória acima de 71%, e IC50 de 0,69 mM. A fração enriquecida em polifenóis extraídos da serrapilheira de P. arachnoideum exerceu atividade inibitória sobre o desenvolvimento inicial de espécies bioindicadoras, nativa e invasora do Cerrado, especialmente sobre o desenvolvimento das raízes dessas plântulas, e atividade sobre as células do metaxilema de gergelim, e sobre o conteúdo de clorofila de gergelim e de capim rabo-de-raposa. O potencial alelopático do principal composto polifenólico desta planta, selligueina A, também foi testado sobre o crescimento inicial de gergelim, promovendo inibição do comprimento final do caule e da raiz de plântulas de gergelim em todas as concentrações testadas. Plântulas de gergelim crescidas na presença de selligueina A apresentaram células do metaxilema menores do que o as do controle nas concentrações de 0,3 mM e 1 mM, com inibição de 50,82% na maior concentração e IC50 de 0,98 mM. Não houve atividade de selligueina A sobre o conteúdo de clorofila dessas plântulas. Análises dos extratos de solo coletado sob manchas de P. arachnoideum apontaram a presença de selligueina A como composto majoritário na solução do solo, e, portanto, como aleloquímico produzido por esta planta. As concentrações do composto no solo variaram entre 0,02 e 0,65 mM. De acordo com resultados de potencial alelopático essa faixa de concentração seria suficiente para
potencialmente atuar sobre espécies co-ocorrentes, favorecendo a dominância de P. arachnoideum. A presença de P. arachnoideum em áreas de Cerrado altera condições químicas do solo, especialmente com relação à concentração do nutriente N e de Al, quando comparada à presença de braquiária (U. decumbens). Além disso, a concentração de Al se encontra correlacionada à massa de serrapilheira e à concentração de selligueina A nas áreas amostradas. Estes resultados corroboram a hipótese de alelopatia como mecanismo de dominância dessa planta nas áreas em que ocorre, com a primeira descrição de um aleloquímico para uma espécie do gênero Pteridium, que apresenta atividade não apenas por fitotoxicidade direta, mas também por ação indireta, ao controlar a concentração de Al nessas áreas.
15
Hadfield, Patrick R. H. "Cyanogenesis in bracken (Pteridium aquilinum (L.) Kuhn)." Thesis, University of Edinburgh, 1986. http://hdl.handle.net/1842/13972.
Texte intégral
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Neto, Cunha Gomes Joana. "Biological effects of Pteridium aquilinum and its toxin in gastric carcinogenesis : relationship with Helicobacter pylori infection." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA114822.
Texte intégralRésumé :
La cancérogenèse gastrique est un processus d’origine multifactorielle, incluant des facteurs génétiques de l’hôte, mais aussi d’origine bactérienne et de l’environnent. Les populations humaines peuvent être exposées directement ou indirectement à des composés toxiques/génotoxiques présents dans les plantes, comme la fougère Pteridium aquilinum. Cette plante comprend une toxine, le ptaquiloside associée à des maladies graves et le développement de cancer chez les animaux. Des études épidémiologiques ont démontré une association entre l'exposition à ces fougères et l’incidence du cancer gastrique dans les populations humaines. Cependant, un autre facteur de risque majeur dans le développement du cancer gastrique est la bactérie Helicobacter pylori qui colonise l'estomac humain et induit une réponse génotoxique. Cette étude vise à caractériser l'implication biologique et moléculaire de Pteridium aquilinum et de sa toxine le ptaquiloside dans le processus de cancérogenèse gastrique et d'explorer un effet de synergie potentiel avec l'infection par H. pylori.Nous avons montré que le traitement avec des extraits de Pteridium aquilinum et le ptaquiloside diminue la viabilité cellulaire et favorise l'apoptose des cellules épithéliales gastriques. L'induction de cassures de l'ADN a été observée, exacerbée en présence de l’infection par H. pylori. Dans les cellules traitées, la protéine p53 est induite et associée à l'activation de la voie de signalisation ATR-Chk1. Cette augmentation de p53 est aussi détectée en présence des souches virulentes de H. pylori. L’induction de lésions à l’ADN par le ptaquiloside est en accord avec la dérégulation observée de l’expression d’un certain nombre de gènes impliqués dans la régulation du cycle cellulaire et la réparation de l'ADN. De plus, des souris exposées à Pteridium aquilinum, montrent des modifications histomorphologiques de la muqueuse gastrique ainsi qu’une augmentation de la prolifération cellulaire et l'induction de mutations dans le gène p53 après 7 semaines de traitement. Toutefois, bien qu’une exacerbation de la prolifération cellulaire et des lésions histologiques soient induites par un traitement chronique en association avec l'infection à H. pylori pendant 12 mois, aucune différence significative dans l'expression du gène p53 a été mise en évidence. Cependant, dans ces conditions, une modification du schéma glycophenotypique a été induite dans la muqueuse gastrique des souris. Différentes glycosyltransférases impliquées dans la biosynthèse des antigènes simples de mucines et terminaux antigènes Lewis ont été différentiellement exprimées chez les souris non-infectées et infectées, respectivement. Ces résultats sont également validés par une augmentation de l’expression de Sialyl-LewisX.De plus, des modifications des glycosyltransférases impliquées dans les étapes initiales de O-glycosylation ont été observées. Le ppGalNAcT6 a présenté une expression altérée dans un carcinome gastrique, associée à la présence de l'invasion veineuse.En conclusion, nos données confirment l’activité génotoxique de Pteridium aquilinum et du ptaquiloside sur les cellules gastriques, supportant leur rôle fondamental dans la promotion de la cancérogenèse gastrique. Cette activité est exacerbée en présence de l’infection par H. pylori, soulignant l'importance de l'interaction de ces deux facteurs de risque dans ce processus<br>The multifactorial gastric carcinogenesis process encompasses host genetic susceptibility, bacterial and environmental factors. Humans can directly consume or be indirectly exposed to toxic compounds present in plants, such as the bracken fern Pteridium aquilinum. This plant has a carcinogenic toxin, ptaquiloside, and is known to cause severe health problems in animals, including cancer. Epidemiological evidence also demonstrated an association between bracken exposure and gastric cancer development in Humans. Additionally, another major etiological agent is Helicobacter pylori, a bacterium that colonizes the stomach inducing a genotoxic response in gastric cells. This study aimed to characterize the biological and molecular involvement of Pteridium aquilinum and its ptaquiloside toxin in the gastric carcinogenesis process and to evaluate the potential synergistic effect of H. pylori infection.We observed that treatment with Pteridium aquilinum extracts and ptaquiloside toxin decreased cell viability and promoted cell apoptosis in gastric epithelial cells. A genotoxic effect with induction of DNA strand breaks was noted and it was exacerbated in the presence of H. pylori infection. We further demonstrated that in treated cells a p53 accumulation occurs, controlled by the activation of the ATR-Chk1 DNA damage signalling pathway. An increased level of p53 was also detected in the presence of a H. pylori virulent strain. The contribution of ptaquiloside to this genotoxic activity was supported by the deregulation of other genes involved in DNA cell cycle regulation and DNA repair. In addition, using a mouse model exposed to Pteridium aquilinum, we detected histomorphological alterations with increased cell proliferation and induction of frameshift events in the p53 gene. However, a concomitant chronic treatment with Pteridium aquilinum and H. pylori infection did not produce significant differences in p53 gene expression.Moreover, an altered glycophenotypic pattern was induced in the gastric mucosa of mice upon Pteridium aquilinum treatment in the presence of H. pylori infection. Several glycosyltransferases involved in the biosynthesis of simple mucin-type carbohydrate antigens and terminal Lewis antigens were differently expressed in the absence and presence of H. pylori, respectively. These results were also validated by an increased expression of Sialyl-LewisX.Further alterations in glycosyltransferases involved in the initial steps of O-glycosylation were observed. The ppGalNAcT6 was shown to have a heterogeneous expression in human gastric carcinoma, associated with the presence of venous invasion.Overall, our data supports the notion that cell exposure to the genotoxic and carcinogenic Pteridium aquilinum and ptaquiloside has a fundamental role in the promotion of gastric carcinogenesis. The synergistic environment associated to H. pylori infection underlines the importance of risk factor interplay in this process<br>A carcinogénese gástrica é um processo multifatorial que engloba fatores genéticos, bacterianos e ambientais. O Homem pode consumir diretamente ou ser exposto de forma indireta a compostos tóxicos presentes em plantas, como é o caso do feto vulgar Pteridium aquilinum. Esta planta tem uma toxina carcinogénica, o ptaquilosídeo, sendo conhecida a sua capacidade natural para induzir lesões neoplásicas em animais. Estudos epidemiológicos também demonstraram a existência de uma associação entre a exposição ao feto e o desenvolvimento de cancro gástrico em humanos. Outro fator etiológico importante é a Helicobacter pylori, uma bactéria que coloniza o estômago, induzindo nas células gástricas uma resposta genotóxica. Este estudo tem por objetivos caracterizar o envolvimento biológico e molecular do Pteridium aquilinum e da sua toxina, ptaquilosídeo, no processo de carcinogénese gástrica e avaliar o potencial efeito sinergístico da infeção por H. pylori.Observámos em células epiteliais gástricas que o tratamento com extratos de Pteridium aquilinum e com a toxina ptaquilosídeo, diminui a viabilidade celular e promove a apoptose. Foi demonstrado um efeito genotóxico com indução de quebras na cadeia de ADN, exacerbado pela presença da infeção por H. pylori. Demonstrámos ainda que, em células tratadas, ocorria uma acumulação de p53, controlada pela ativação da via de sinalização ATR-Chk1. Um aumento nos níveis de p53 foi igualmente detetado na presença de estirpes virulentas de H. pylori. A contribuição do ptaquilosídeo para esta atividade genotóxica foi também apoiada pela desregulação de outros genes envolvidos na regulação do ciclo celular e na reparação do ADN. Adicionalmente, usando um modelo de ratinho exposto ao Pteridium aquilinum, foram detetadas alterações histomorfológicas, bem como um aumento da proliferação celular e indução de mutações no gene p53. Contudo, um tratamento crónico com Pteridium aquilinum e infeção concomitante por H. pylori não produziu diferenças significativas na expressão do gene p53.Um padrão glicofenotípico alterado foi também observado na mucosa gástrica de ratinhos tratados com Pteridium aquilinum na presença de infeção por H. pylori. Várias glicosiltransferases envolvidas na biossíntese de antigénios simples das mucinas e antigénios terminais do tipo Lewis apresentaram uma expressão alterada, respetivamente, na ausência ou presença de H. pylori. Estes resultados foram também validados através de um aumento da expressão de Sialil-LewisX.Foram ainda observadas alterações em glicosiltransferases que estão envolvidas nas etapas iniciais de O-glicosilação. A ppGalNAcT6 apresentou uma expressão alterada em carcinomas gástricos, estando associada à presença de invasão venosa.No geral, estes dados suportam a evidência de que a exposição das células aos genotóxicos e carcinogénicos Pteridium aquilinum e ptaquilosídeo, tem um papel fundamental na promoção da carcinogénese gástrica. O ambiente sinergístico associado à infeção com H. pylori salienta a importância da interação entre os fatores de risco que dão origem a este processo
17
Lin, Xinli. "Isolation and characterization of new pterins from nonmethanogenic archaebacteria." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/77823.
Texte intégralRésumé :
Several new pterins have been discovered in halophilic and thermoacidophilic archaebacteria. Two of these were identified in the extreme halophiles and were thus called halopterins. One of these halopterins is produced by Halobacterium salinarium, Halobacterium halobium, and Halococcus morrhuae and is called phosphohalopterin-1. It was given this name because it was the first halopterin discovered and it has four monophosphate esters per dimeric pterin. The proposed structure of phosphohalopterin-1 is as follows. [see document for diagram of chemical structure]
The other halopterin, which is produced by Halobacterium marismortui, Halobacterium volcanii, and Halobacterial strain GN-1, is called sulfohalopterin-2 because it has two sulfate esters per dimeric pterin and it was isolated and recognized after the isolation of phosphohalopterin-1. The proposed structure of sulfohalopterin-2 is as follows. [see document for diagram of chemical structure]
As shown above, both pterins are dimers with an ether linkage connecting the polyol side chains. Both of the halopterins are negatively charged because of the phosphate and sulfate esters on the side chains. In addition to the halopterins, a positively charged pterin has been isolated from Sulfolobus solfataricus. This pterin is very special since no positively charged unconjugated pterin had ever been found in nature before. This pterin is named solfapterin after the species name of the bacteria from which it was obtained. The structure of this pterin is still unknown but the preliminary data indicate that it is an unconjugated pterin with a polyol containing an amine on the side chain. Another positively charged pterin which is different from solfapterin was found in Thermoplasma. All of the above pterins are different from any previously described pterins and thus represent new pterins in the archaebacterial kingdom.
The discovery of these new pterins is important both to pterin biochemistry and to archaebacterial taxonomy. These discoveries also open up a new field, that is, the exploration of the function of these new pterins in norunethanogenic archaebacteria.<br>Ph. D.
18
Oliveira, Rui Miguel Gil da Costa. "Studies on the biopathological actions of Pteridium aquilinum." Tese, Instituto de Ciências Biomédicas Abel Salazar, 2011. http://hdl.handle.net/10216/63596.
Texte intégral
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Oliveira, Rui Miguel Gil da Costa. "Studies on the biopathological actions of Pteridium aquilinum." Doctoral thesis, Instituto de Ciências Biomédicas Abel Salazar, 2011. http://hdl.handle.net/10216/63596.
Texte intégral
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Mohammad, Rizgar Hassan. "Pterosins and pterosides in bracken (Pteridium aquilinum (L.) Kuhn)." Thesis, Bangor University, 2016. https://research.bangor.ac.uk/portal/en/theses/pterosins-and-pterosides-in-bracken-pteridium-aquilinum-l-kuhn(b7ccd2e5-8120-49e9-b825-15e071d1da75).html.
Texte intégralRésumé :
An intensive study was undertaken in order to isolate and identify bioactive compounds in bracken, Pteridium aquilinum (L.) Kuhn (Dennstaedtiaceae). A systematic phytochemical investigations of the underground rhizomes of this plant afforded thirty-five pterosins and pterosides along with the main carcinogen in bracken, ptaquiloside, 5-hydroxyisocalamene and 5-(β-hydroxy)ethyl-2, 2, 4, 6-tetramethyl-1, 3-indandione. By detailed analysis of one- and two-dimensional nuclear magnetic resonance spectroscopy, circular dichroism and highresolution mass spectrometric data, thirteen previously undescribed pterosins and pterosides have been identified. Interestingly, for the first time 12-O-β-D-glucopyranoside substituted pterosins, rhedynosides C and D, and the sulfate-containing pterosin, rhedynosin H, alongside the two known compounds, trans-histiopterosin A and (2S)-pteroside A2, were isolated from the rhizomes of subsp. aquilinum of bracken. In addition, the six-membered cyclic ether pterosins and pterosides rhedynosin A and rhedynoside A are the first examples of this type of pterosin-sesquiterpenoids. Additionally, the three previously reported compounds [(2S)- rhedynosin I, (2S)-2-hydroxymethylpterosin E and (2S)-12-hydroxypterosin A] were obtained for the first time from plant source as opposed to mammalian metabolic products. Single crystal X-ray diffraction analysis was applied to the previously undescribed compounds (2R)- rhedynoside B, (2R)-pteroside B and (2S)-pteroside K, yielding the first crystal structures for pterosides, and three known pterosins, (2S)-pterosin A, trans-pterosin C and cis-pterosin C. Rhedynosin C is the only example of the cyclic lactone pterosin with a keto group at position C-14. Six selected pterosins ((2S)-pterosin A, (2R)-pterosin B and trans-pterosin C) and associated glycosides ((2S)-pteroside A, (2R)-pteroside B and pteroside Z) were assessed for their anti-diabetic activity using an intestinal glucose uptake assay; all were found to be inactive at 300 μM. A simple, reproducible and rapid reverse phase high performance liquid chromatography (RP-HPLC) method was developed which was linked to the UV detection source. The method validated for quantification of pterosin B and pteroside B in different plant matrices, soil and water samples. A new solid phase extraction (SPE) method was developed and established for sample preparation based on using 500 mg Supelco-SPE cartridges. The RP-HPLC was performed with mobile phase containing 0.1% formic acid (FA) in water and 0.1% FA in acetonitrile with an appropriate gradient and a flow rate of 1 mL/min. Detection of the analyte peaks was performed at 254 nm. The method showed good linearity (correlation coefficient (r) > 0.99), and appropriate limit of detection (LOD) and limit of quantification (LOQ). The proposed RP-HPLC-UV method has a retention time of 20 min (3 samples/h). Overall, this work focuses on the application of SPE–HPLC-UV analysis to quantify pterosin B and pteroside B in different matrices including soil, water and bracken samples. The method involves pre-concentration and clean-up by SPE cartridges. Final analysis of the selected compounds was carried out by the developed HPLC-UV method. The extraction efficiency was checked by recovery experiment while the accuracy of the method was tested by relative standard deviation (% RSD). Recoveries were ranged from 90.29 to 96.23 % (pterosin B) and 93.64 to 101.03 % (pteroside B). The RSD (%) for both target analytes (pterosin B and pteroside B) was less than 2.5 % for all the analysed bracken stem samples. Preliminary results demonstrated that the present method was suitable for determination of pterosin B and pteroside B in bracken tissues, soil and water samples. The simplicity, accuracy and sensitivity of the developed SPE-HPLC-UV method, recommending that the method is also convenient and useful for quick check and detection of trace amounts of pterosin B and pteroside B in water, soil and plant samples. The quantification of pterosin B and pteroside B was applied to bracken, divided into rhizomes, stems and fronds, the top soil of the sample cores and a set of water samples. The rhizome contained the largest concentration of pteroside B through the completed bracken growth period (750-2950 mg/kg). Its concentration was approximately one order of magnitude above pterosin B (10-245 mg/kg). The above ground stems and fronds showed distinct increases in concentrations of pterosin B (ca. 500 mg/kg) and pteroside B (ca. 250 mg/kg) at the time of crosier emergence, that were about one order of magnitude higher than the other samples collected during the growth periods. The soil sampled reflected the increased mobilisation of pterosin B during the onset of above ground growth (May to June) while no pteroside B was detected. The absolute pterosin B concentrations determined were about three orders of magnitudes lower (0.02-0.3 mg/kg). Water samples that drain bracken covered areas were found to contain pterosin B between 9-47 ng/L and pteroside B in range of 16-85 ng/L. Overall, the seasonal variation of pterosin B and pteroside B showed that the compounds are stored in the rhizome, preferably as the glycoside, and are mobilised to protect the early tissue as a means of chemical defence. The stability of pterosin B was exemplified by its environmental presence in plant, soil and water.
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Dolghih, Elena. "Bacterial Cyanide Assimilation: Pterin Cofactor and Enzymatic Requirements for Substrate Oxidation." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4525/.
Texte intégralRésumé :
Utilization of cyanide as the sole nitrogen source by Pseudomonas fluorescens NCIMB 11764 (Pf11764) occurs via oxidative conversion to carbon dioxide and ammonia, the latter satisfying the nitrogen requirement. Substrate attack is initiated oxygenolytically by an enzyme referred to as cyanide oxygenase (CNO), which exhibits properties of a pterin-dependent hydroxylase. The pterin requirement for Pf11764 CNO was satisfied by supplying either the fully (tetrahydro) or partially (dihydro) reduced forms of various pterin compounds at catalytic concentrations (0.5 µM). These compounds included, for example, biopterin, monapterin and neopterin, all of which were also identified in cell extracts. A related CNO-mediated mechanism of cyanide utilization was identified in cyanide-degrading P. putida BCN3. This conclusion was based on (i) the recovery of CO2 and NH3 as enzymatic reaction products, (ii) the dependency of substrate conversion on both O2 and NADH, and (iiii) utilization of cyanide, O2 and NADH in a 1:1:1 reaction stoichiometry. In contrast to findings reported for Pf11764, it was not possible to demonstrate a need for exogenously added pterin as a cofactor for the PpBCN3 enzyme system. However, results which showed that cells of PpBCN3 contained approximately seven times the amount of pterin as Pf11764 (of which a significant portion was protein-bound) were interpreted as indicating that sufficient bound CNO-cofactor exists, thus eliminating any need for a supplemental source.
22
Latorre, Andréia Oliveira. "Avaliação dos efeitos imunotóxicos da Pteridium aquilinum. Estudo em camundongos." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/10/10133/tde-02032007-123407/.
Texte intégralRésumé :
Pteridium aquilinum, conhecida popularmente como "samambaia-do-campo" ou simplesmente "samambaia", é considerada uma das plantas tóxicas mais importantes no mundo, não só pela sua distribuição cosmopolita e intoxicação de rebanhos em diversas partes do mundo, mas também pelo seu alto potencial carcinogênico observado em animais e seres humanos que se alimentam com esta planta. Por outro lado, não havia dados na literatura a respeito dos possíveis efeitos tóxicos desta planta sobre o sistema imune, o qual se sabe, tem papel fundamental não só para o controle de doenças infecciosas, como também, para impedir a proliferação de células mutantes e, conseqüentemente o desenvolvimento de câncer. Assim, o presente estudo avaliou os efeitos da P. aquilinum sobre as respostas imune inata e adaptativa em camundongos, através dos seguintes protocolos: produção e titulação de anticorpos T - dependente, proliferação de linfócitos T e B, resposta de hipersensibilidade tardia, fenotipagem linfocítica e citotoxicidade de células NK. Além disso, foram feitas a avaliação histológica e a contagem da celularidade dos órgãos linfóides. Resultados mostraram diminuição da resposta de hipersensibilidade tardia (resposta celular) nos grupos tratados com 10 e 30 g/kg de samambaia, redução da citotoxicidade das células NK, redução da polpa branca do baço, diminuição da camada celular do timo e desorganização dos folículos linfóides nos linfonodos mesentéricos e placas de Peyer dos camundongos tratados com a dose de 30 g/kg de samambaia e diminuição na celularidade da medula óssea em todos os grupos tratados com a samambaia, por 14 dias. Os dados obtidos na presente pesquisa permitem sugerir que a diminuição da resposta imune celular foi decorrente do efeito tóxico da P. aquilinum sobre as células NK e não um efeito tóxico direto sobre os linfócitos Th1.<br>Pteridium aquilinum, known popularly as \"bracken fern\" is considered one of the more important toxic plants in the world, not only for its cosmopolite distribution and poisoning of flocks in diverse parts of the world, but also for its high potential carcinogenicity observed in animals and human that feed with this plant. On the other hand, there are not data available in the literature regarding the possible toxic effects of this plant on the immune system that is fairly known to be important not also for the control of infectious illnesses but also to hinder the proliferation of mutant cells and, consequently cancer development. Thus, the present study evaluated the effect of the P. aquilinum on the innate and acquired immune responses in mice, through the following protocols: production and titer of T - dependent antibody, proliferation of T and B lymphocytes, delayed-type hypersensitivity, lymphocyte subset analysis and natural killer-cell activity. Moreover, histophatological evaluation and cellularity of the lymphoid organs were performed. Results showed reduction of the delayed-type hypersensitivity (cellular immune response) of the mice treated with 10 and 30 g/kg of bracken fern. Besides, it was observed reduction of the natural killer-cell cytotoxicity, decrease of white pulp of spleen and of the cellular layer of the thymus, disorganization of the lymphoid follicle in the mesenteric lymph nodes and Peyer?s patches of the mice treated with 30 g/kg. It was also observed decrease of bone marrow cellularity of all animals treated with bracken fern up to 14 days. Thus, these data found here permit to suggest that P. aquilinum produced reduction of the cellular immune response by a direct toxic effect on the natural-killer cells and not on the Th1 lymphocytes.
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Ogunbiyi, Adetokunbo Olawale. "Aspects of the toxicology of the bracken fern (Pteridium aquilinum)." Thesis, University of Surrey, 1987. http://epubs.surrey.ac.uk/844019/.
Texte intégralRésumé :
Aspects of the toxicology of bracken (Pteridium aguilinum) were studied in sub-acute and chronic studies using male Wistar-albino rats. In a chronic study, bracken induced ileal adenomas in an 8.5 month period but after 24 months, no tumours were seen in both the quercetin- and shikimate-fed rats. Tissue ornithine decarboxylase (ODC) levels were enhanced over a 90-day test period when shikimate was fed alone or in conjunction with BBN and MNNG as initiators and with cyclophosphamide, saccharin and lithocholate as promoters, suggesting that shikimate might be a tumour promoter. Quercetin, was able to enhance ODC levels in conjunction with cyclophosphamide, BBN and MNNG as initiators and with cyclophosphamide, saccharin and lithocholate as promoters. However, it did not enhance tissue ODC levels when administered alone. Bracken, shikimate and quercetin induced a macrocytic, normochromic, non-regenerative anaemia with thrombocytopenia and granulocytopenia at the termination of the 90-day study. The bracken-induced ataxia of monogastrics was attributed additionally to nitrite and cyanide, due to the very high levels found in the urine and serum respectively of bracken-fed rats over a 28-day test period. The high urinary nitrite levels of the bracken-fed rats prompted an investigation into the role of N-nitrosation in bracken-induced carcinogenesis. To this end, the Nitrosation Assay period (NAP) revealed the presence of nitrosatable entities in the gut of the bracken-, quercetin- and shikimate-fed rats and in the urine of the bracken- and quercetin-fed rats. This suggests that nitrosation, probably via the formation of nitrosamides, might be an important mechanism for the mediation of bracken-induced carcinogenesis. The plausibility of explaining various aspects of the sub-acute and chronic toxicity of bracken in monogastrics and ruminants on the basis of a "nitrosamide hypothesis" is discussed.
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Alfenas, Rafael Ferreira. "Produção de inóculo de Cylindrocladium pteridis em condições controladas." Universidade Federal de Viçosa, 2009. http://locus.ufv.br/handle/123456789/4375.
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Previous issue date: 2009-10-26<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>To base the cultivation of Cylindrocladium pteridis and inoculation of the fungus under controlled conditions, was evaluated in this study sporulation in culture, conidial germination, mycelial growth and defoliation of eucalyptus at different temperatures. In preliminary experiments, we evaluated the effect of light and incubation time on germination of conidia. The presence of continuous light significantly reduced germination, resulting in higher germination of conidia in the dark. In assessing the germination under different incubation periods, it was observed that the germination of C.pteridis is very fast, and obtained 100% conidia germinated after 4 h of incubation. In assessing the germination under different temperatures, the optimum for germination was 25 ° C (84.6%). The mycelial growth also varied with temperature, and the maximum was 25 ° C. Aiming to solve the problem of low production of conidia in vitro were evaluated three methods of sporulation of C. pteridis in culture. We compared three methods, and the method of scraping the aerial mycelium followed by flood water was the most sporulation in media AVDA, MEA, PDA and GAA, after 10 days of incubation. We obtained the greatest number of conidia on PDA, with an average of 14.13 x 104 conidia / mL. With half SNA was no significant difference between the methods studied. Subsequently, to study the effect of temperature on leaf eucalyptus, is inoculated plants were kept in a moist chamber at 18, 26, 28 and 30 º C. After 48 h, were transferred to a greenhouse (25 ± 5 º C). The temperature significantly influenced the leaf classes in the base of the crown 50 days after inoculation, and the highest percentage of defoliation occurred at 26 º C.<br>A fim de embasar o cultivo de Cylindrocladium pteridis e a inoculação do fungo em condições controladas, avaliou-se neste trabalho a esporulação em cultura, a germinação de conídios, o crescimento micelial e a desfolha causada em eucalipto sob diferentes temperaturas. Em experimentos preliminares, avaliou-se o efeito da luminosidade e o tempo de incubação na germinação de conídios. A presença de luz contínua reduziu significativamente a germinação, obtendo-se maior germinação de conídios no escuro. Ao avaliar a germinação sob diferentes períodos de incubação, observou-se que a germinação de C.pteridis é muito rápida, sendo obtido 100% de conídios germinados após 4 h de incubação. Ao avaliar a germinação sob diferentes temperaturas, o ótimo para germinação foi 25 °C (84,6%). O crescimento micelial também variou com a temperatura, e o máximo foi a 25 ºC. Objetivando-se solucionar o problema da baixa produção de conídios in vitro, avaliaram-se três métodos de esporulação de C. pteridis em cultura. Compararam-se três métodos, e com o método de raspagem do micélio aéreo seguido de inundação em água obteve a maior esporulação do fungo nos meios AVDA, MEA, BDA e GAA, após 10 dias de incubação. Obteve-se a maior produção de conídios em BDA, com média de 14,13 x 104 conídios/mL. Com o meio SNA não houve diferença significativa entre os métodos estudados. Posteriormente, para se estudar o efeito da temperatura na desfolha em eucalipto, inocularam-se plantas que foram mantidas em câmara úmida a 18, 26, 28 e 30 ºC. Após 48 h, foram transferidas para casa de vegetação (25±5 ºC). A temperatura influenciou significativamente a desfolha em ramos da base da copa aos 50 dias após inoculação, e o maior percentual de desfolha ocorreu a 26 ºC.
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Leite, Franco Henrique Andrade. "Planejamento e avalia??o de novos inibidores de Pteridina Redutase 1 (PTR1) de Leishmania major." Universidade Estadual de Feira de Santana, 2015. http://localhost:8080/tede/handle/tede/279.
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Previous issue date: 2015-11-06<br>Conselho Nacional de Pesquisa e Desenvolvimento Cient?fico e Tecnol?gico - CNPq<br>According to WHO, Leishmaniasis is the second most important disease caused by protozoans. However, the available therapeutic arsenal for its treatment is limited and has low efficacy and safety profile. Once Leishmania ssp. are pteridine auxotrophs key enzymes of the folate metabolism have been targeted to circumvent this dilemma. However, Dihydrofolate Reductase-Thymidylate Synthase (DHFR-TS) inhibitors are ineffective against Leishmania major due to an alternative folate pathway regulated by Pteridine Reductase 1 (PTR1). Thus, identifying molecules that act on both enzymes is crucial to develop new leishmanicidal drugs. For that reason, the main goal of this study is to identify, through in silico approaches, (pharmacophore models), putative PTR1 inhibitors that also show structural requirements for L. major DHFR-TS inhibition. The pharmacophore models 10 and 20, PTR1 (2 H-bond donors, 4 H-bond acceptors and 3 hydrophobic centers) and DHFR-TS inhibitors (2 H-bond acceptors and 2 hydrophobic centers) respectively, show high performance to differentiate true-binders from decoys (AUCPTR1=0.90; AUCDHFR-TS=0.86) and to explain the structure-activity relationships for the inhibitors under study. Thus, these models were employed sequentially to select 10 molecules whose effect over the thermal stability of LmPTR1 was investigated by ThermoFluor?. According to this assay, two molecules stabilize LmPTR1: Z80393 (?Tm = 1.02?C) and Z33165 (?Tm = 0.9?C). Binding displacement assays with biopterin or NADPH showed that Z80393 binds within the substrate binding site, whereas Z33165 binds in the cofactor binding site. Z80303 effect over the catalytic activity of PTR1 was investigated by fluorimetry. This approach allowed us to determine the inhibitor?s potency (IC50=32.31 ? 1.18 ?M). Finally, Z80303 putative binding profile was generated by molecular docking and analyzed by Molecular Dynamics (productive phase= 15 ns). The results show that during 70% of the simulation, Z80393 H-bonds to Ser-111 and Arg-17 residues. Therefore, this study not only led to identification of a new class of LmPTR1 inhibitors, but also allowed us to determine its potency, mode of inhibition and binding profile towards its therapeutic target.<br>A leishmaniose tem sido indicada pela OMS como a segunda protozoose mais importante em termos de mortalidade e preval?ncia. Entretanto, o repert?rio de f?rmacos dispon?veis ? limitado e apresenta, na maioria dos casos, baixos ?ndices de efic?cia e seguran?a. Embora os protozo?rios do g?nero Leishmania sejam auxotr?ficos para folatos, inibidores da Diidrofolato Redutase-Timidilato Sintase (DHFR-TS) s?o pouco eficazes contra esse parasito. A baixa suscetibilidade se explica pela presen?a da Pteridina Redutase 1 (PTR1) que atua como via alternativa para a redu??o de ?cido f?lico ou de pteridinas n?o conjugadas, quando DHFR-TS est? inibida. Diante desse cen?rio, mol?culas que atuam sobre PTR1 e DHFR-TS de Leishmania ssp. parecem ser promissoras para o desenvolvimento de f?rmacos contra a leishmaniose. Por essa raz?o, o objetivo desse trabalho foi identificar, por triagem in silico (modelo farmacof?rico), potenciais inibidores de PTR1 que apresentem os requisitos estruturais m?nimos para inibir tamb?m DHFR de L. major. Os modelos farmacof?ricos 10 e 20, baseados em inibidores de PTR1 (2 doadores de lig. H, 4 aceitadores de lig. H e 3 centros hidrof?bicos) e DHFR-TS (2 aceitadores de lig. H e 2 centros hidrof?bicos) respectivamente, mostraram desempenho satisfat?rio em discriminar inibidores verdadeiros de falsos positivos (AUCPTR1=0,90; AUCDHFR-TS=0,86), al?m de explicarem a rela??o entre a estrutura qu?mica e a atividade biol?gica. Esses modelos foram usados sequencialmente para selecionar 10 mol?culas que tiveram seu efeito sobre a estabilidade t?rmica de LmPTR1 investigado por ThermoFluor?. Nesse ensaio foram identificadas duas mol?culas que estabilizaram LmPTR1: Z80393 (?Tm = 1,02?C) e Z33165 (?Tm = 0,9?C). Ensaios de deslocamento com biopterina ou NADPH mostraram que Z80393 compete com o substrato, enquanto Z33165 interage no s?tio do cofator. O efeito de Z80393 sobre a atividade catal?tica de LmPTR1 foi investigado por fluorimetria, permitindo determinar a pot?ncia desse inibidor (IC50=32,31 ? 1,18 ?M). Por fim, um modelo de intera??o para esse inibidor foi gerado por acoplamento molecular e a pose obtida foi analisada atrav?s de uma Din?mica Molecular com fase produtiva de 15 ns. Os resultados obtidos mostram que durante 70% da simula??o, Z80393 faz liga??es de H com os res?duos Ser-111 e Arg-17. Portanto, o presente trabalho n?o s? levou a identifica??o de uma nova classe de inibidores de LmPTR1, mas tamb?m permitiu caracterizar sua pot?ncia, modalidade de inibi??o e perfil de intera??o com seu alvo terap?utico.
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Anjos, Bruno Leite dos. "Intoxicação aguda espontânea e experimental por samambaia (Pteridium aquilinum) em bovinos." Universidade Federal de Santa Maria, 2009. http://repositorio.ufsm.br/handle/1/10032.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico<br>The epidemiology, pathogenesis, clinical and pathological aspects of the spontaneous and
experimental poisoning of cattle by bracken fern (Pteridium aquilinum) were studied. Two
scientific papers that stemmed from these studies are presented and discussed here. Initially,
6,256 necropsy reports from cattle necropsied during a de 43-year-period (1964-2006) were
reviewed. Of those, 15 cases were consistent with acute poisoning caused by the ingestion of P.
aquilinum and they occurred in cattle from small farms in the Central region of the State of Rio
Grande do Sul, Brazil. In 40% of the farms the disease occurred in small outbreaks affecting
several cattle per farm and in 60% only one bovine was affected in each farm. Morbidity and
mortality were 17.9% and lethality was virtually 100%. The poisoning was experimentally
produced in four calves; it was concluded that exclusively the events of the primary hemostasis
due to thrombocytopenia are responsible for the hemorrhages. Blood culture from three affected
calves yield the growth of Klebsiella oxytoca, Staphylococcus hyicus and S. aureus, indicating
that septicemia, facilitated by neutropenia could have a role in the death of cattle acutely
poisoned due to the ingestion of P. aquilinum.<br>Foram estudados a epidemiologia, a patogênese, os aspectos clínicos e patológicos da
intoxicação aguda, espontânea e experimental, por samambaia (Pteridium aquilinum) em
bovinos. Dois trabalhos científicos que resultaram desse estudo são aqui apresentados e
discutidos. Inicialmente, foram revisados 6.256 laudos de necropsia de bovinos num período de
43 anos (1964-2006). Desses, 15 casos corresponderam a quadros de intoxicação aguda causada
pela ingestão de P. aquilinum e os casos ocorreram em bovinos de pequenas propriedades rurais
da Região Central do Rio Grande do Sul. Em 40% das propriedades a doença ocorreu em
pequenos surtos e em 60% delas apenas um bovino era afetado por propriedade. As taxas médias
de morbidade e mortalidade foram de 17,9% e a letalidade foi virtualmente 100%. A intoxicação
foi produzida experimentalmente em quatro bovinos e foi demonstrado que apenas eventos da
hemostasia primária devidos a trombocitopenia são responsáveis pelas hemorragias. A
hemocultura de três dos bovinos intoxicados produziu crescimentos de Klebsiella oxytoca,
Staphylococcus hyicus e S. aureus, indicando que a septicemia, facilitada pela neutropenia, pode
ter participação na causa da morte de bovinos na intoxicação aguda pela ingestão de P.
aquilinum.
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Ader, Katherine Gwyneth. "Factors controlling the distribution and spread of bracken (Pteridium Aquilinum) in Scotland." Thesis, University of Glasgow, 1988. http://theses.gla.ac.uk/1564/.
Texte intégralRésumé :
The aim of this thesis is to investigate the factors controlling the spread and distribution of bracken (Pteridium aquilinum) in Scotland. Bracken has long been an agricultural problem and, more recently, fears have been raised about the plant's carcinogenic properties. Despite the seriousness of the problem, there has been little quantitative research into factors controlling the plant's vigour, although there are many anecdotal references on the subject. It is the aim of this thesis to; study the climatic, edaphic and biotic characteristics of the bracken zone; establish the statistical relationship between these factors and bracken vigour and to apply the findings to explain how these factors affect bracken in Scotland. The climatic, soil, vegetation and biotic characteristics of four sites in the bracken zone (west, south-west, north-east and south-east) are reviewed first. By comparisons of inter-site factors and bracken vigour at the sites, it is possible to formulate hypotheses on the factors that control bracken vigour. Correlation and regression analyses of individual factors with frond height, density and litter depth are than carried out, followed by a Stepwise Regression Analysis. Finally the findings of the two sections are summarised and the results applied to explain bracken distribution and spread in Scotland. The major conclusions of this thesis can be summarised as follows: Early season temperature strongly affects bracken vigour and largely accounts for the east-west difference in bracken vigour. Vigorous bracken in the west can withstand a greater degree of frosting than the less vigorous bracken in the east. Soil moisture stress, heavy frost and relatively intensive agriculture in the east results in a higher bracken zone (and therefore suboptimal soils and temperatures) in the east than in the west.
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Paterson, Stephen. "Control and modelling of bracken (Pteridium Aquilinum (L.) Kuhn) in Great Britain." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318285.
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Marty, Dominique, and Nicole Videau. "Les Landes à fougères aigle ( Pteridium aquiliunum ) des Pyrénées françaises : étude phytogéographique." Toulouse 2, 1987. http://www.theses.fr/1987TOU20011.
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Les landes a fougere presentent une extension geographique et une unite physionomique sur l'ensemble de la zone de moyenne montagne des pyrenees francaises. A partir de ce constat, une synthese agro-ecologique a ete menee dans quatre secteurs de reference (pays basque, bigorre, ariege, vallespir). La definition d'un systeme utilisee comme modele d'investigation est fondee sur une double base : une approche systemique de l'objet d'etude et une approche diagonale de l'espace. La gestion de l'ensemble agro-pastoral des landes a fougere est regie par les brulis qui en est le processus regulateur. Des reconversions de ces landes sont effectuees a partir des defrichements, (controles chimique, mecanique. . . ). L'etude definit des structures phytogeographiques et le fonctionnement du "systeme fougere"<br>Bracken moors present a geographical extension as a physiognomical unity all over french pyrenees mountain zone. From this statement on, an agroecological synthesis was lead in four referring areas (pays basque, bigorre, ariege, vallespir). The definition of a system used as an investigation pattern, is based upon a double ground : - a systemic approach of the studied object - a diagonal approach of space the management of the agro-pastoral entirety of bracken moors is ruled by the burning which is its regulating process. Reconversion of these moors are effected after clearing (chemical, mechanical control). Tis study definies the phytogeographical structures and the working of a "bracken system"
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Der, Joshua, Michael Barker, Norman Wickett, Claude dePamphilis, and Paul Wolf. "De novo characterization of the gametophyte transcriptome in bracken fern, Pteridium aquilinum." BioMed Central, 2011. http://hdl.handle.net/10150/610016.
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BACKGROUND:Because of their phylogenetic position and unique characteristics of their biology and life cycle, ferns represent an important lineage for studying the evolution of land plants. Large and complex genomes in ferns combined with the absence of economically important species have been a barrier to the development of genomic resources. However, high throughput sequencing technologies are now being widely applied to non-model species. We leveraged the Roche 454 GS-FLX Titanium pyrosequencing platform in sequencing the gametophyte transcriptome of bracken fern (Pteridium aquilinum) to develop genomic resources for evolutionary studies.RESULTS:681,722 quality and adapter trimmed reads totaling 254 Mbp were assembled de novo into 56,256 unique sequences (i.e. unigenes) with a mean length of 547.2 bp and a total assembly size of 30.8 Mbp with an average read-depth coverage of 7.0x. We estimate that 87% of the complete transcriptome has been sequenced and that all transcripts have been tagged. 61.8% of the unigenes had blastx hits in the NCBI nr protein database, representing 22,596 unique best hits. The longest open reading frame in 52.2% of the unigenes had positive domain matches in InterProScan searches. We assigned 46.2% of the unigenes with a GO functional annotation and 16.0% with an enzyme code annotation. Enzyme codes were used to retrieve and color KEGG pathway maps. A comparative genomics approach revealed a substantial proportion of genes expressed in bracken gametophytes to be shared across the genomes of Arabidopsis, Selaginella and Physcomitrella, and identified a substantial number of potentially novel fern genes. By comparing the list of Arabidopsis genes identified by blast with a list of gametophyte-specific Arabidopsis genes taken from the literature, we identified a set of potentially conserved gametophyte specific genes. We screened unigenes for repetitive sequences to identify 548 potentially-amplifiable simple sequence repeat loci and 689 expressed transposable elements.CONCLUSIONS:This study is the first comprehensive transcriptome analysis for a fern and represents an important scientific resource for comparative evolutionary and functional genomics studies in land plants. We demonstrate the utility of high-throughput sequencing of a normalized cDNA library for de novo transcriptome characterization and gene discovery in a non-model plant.
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Freitas, Rodrigo Galvão de. "Diversidade genética e agressividade de isolados de Calonectria pteridis no Brasil." Universidade Federal de Viçosa, 2016. http://www.locus.ufv.br/handle/123456789/10802.
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Previous issue date: 2016-07-27<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico<br>A mancha-de-pteridis, causada por Calonectria pteridis, é, atualmente, uma das principais doenças foliares em plantações de eucalipto no Brasil. Em regiões de clima quente e úmido, a doença pode ser um fator limitante para o plantio de genótipos suscetíveis. O método mais eficaz de controle da doença no campo é o plantio de material resistente, o que requer o conhecimento da variabilidade genética e fisiológica na população do patógeno para a seleção de plantas. Neste trabalho avaliaram-se a diversidade genética e a agressividade de C. pteridis obtidos de vários clones de eucalipto em diferentes regiões do Brasil. Estudaram-se 90 isolados provenientes principalmente dos estados do Pará e Maranhão. Para o estudo da diversidade genética, dentre os 16 primers ISSR testados, empregaram-se cinco que foram polimórficos e reprodutíveis. Análises de diversidade genética permitiram identificar 33 genótipos entre os 90 isolados estudados, porém geneticamente próximos, indicando uma baixa diversidade entre eles. Para o estudo da agressividade inocularam-se em dois clones híbridos de Eucalyptus grandis x E. urophylla, sob condições controladas, 16 isolados selecionados com base na origem geográfica e na diversidade genética. A avaliação da severidade foi feita através do percentual de desfolha e por atribuição de notas de acordo com uma escala diagramática, sendo analisada a correlação entre elas. Não houve correlação entre a variabilidade genética e fisiológica, pois os indivíduos diferiram em agressividade. Houve uma alta correlação entre as duas formas de avaliação para apenas um dos clones utilizados. Os isolados GFP004, LPF059 e LPF294 foram os mais agressivos e devem ser empregados nas inoculações para selecionar plantas resistentes à mancha-de-pteridis.<br>Calonectria leaf blight caused by Calonectria pteridis, is, currently, one of the major foliar diseases of eucalyptus plantations in Brazil. In humid and warm regions, it may be a limiting factor for growing suscetible genotypes. The most effective method of disease control in the field is by planting resistant plant material, which requires knowledge of the genetic and physiological variability in the pathogen population for screening for plants. In this work we evaluated the genetic diversity and the aggressiveness of C. pteridis obtained by several eucalyptus clones in different regions of Brazil. We studied 90 isolates collected mainly from the states of Pará and Maranhão. To study the genetic diversity, among 16 ISSR primers tested, five who were polymorphic and reproducible were used. Genetic diversity analysis have identified 33 genotypes among the 90 isolates studied, but genetically related, indicating a low diversity among them. To study the aggressiveness, we inoculated into two hybrid clones of Eucalyptus grandis x E. urophylla, under controlled conditions, 16 isolates selected based on the geographic origin and genetic diversity. The severity assessment was performed using the percentage of defoliation and attribution of notes through a diagrammatic scale, and subsequently analyzed the correlation between them. There was no correlation between the genetic and physiological variability, because individuals differ in aggressiveness. There was a high correlation between the two forms of evaluation to only one of the clones used. The GFP004, LPF059 and LPF294 isolates were the most aggressive and should be used in inoculations to select plants resistant to Calonectria leaf blight.
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Donnelly, Eric. "Potential uses of bracken (Pteridium aquilinum (L.) Kuhn) in organic agriculture in Scotland." Thesis, University of Aberdeen, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274892.
Texte intégralRésumé :
To assess the availability of bracken and the factors influencing frond yields, this thesis investigated the growth and phenology of bracken populations across Scotland in relation to site characteristics. The change in elements in fronds and litter from April to November was analysed, along with the concentrations of the carcinogen Ptaquiloside (Pta). Frond dry matter yields increased to maximum in August/September, falling to those in November. In September/October, frond yields ranged from 4.70-15.9 DM t ha<sup>-1</sup>. Frond concentrations of phosphorus and potassium reduced, and concentrations of calcium and magnesium increased from May to November. Frond Pta concentrations reduced during this period also, with the highest concentration recorded of 5792 mg kg<sup>-1</sup> in May 2002 at Loch Grannoch, SW Scotland. This thesis also investigated the effects of harvesting of fronds, and the burning and clearing of litter on the yield of frond dry matter, yield and content of ash and on Pta concentrations in fronds. The concentration of twenty-one elements, the CaCO<sub>3</sub> equivalence and pH of this ash were determined, and the effect of harvesting of fronds on subsequent yields was assessed. Harvesting during the growing season reduced the preceding yield of fronds, but not if harvested after senescence. A positive regression was found between frond DM and ash yields. The maximum yield of K in ash was harvested in August/September, at around 180 kg ha<sup>-1</sup>. Calculations of the value of bracken ash using August 2001 K concentrations and the cost of other organic K sources came to between £219-£980 t<sup>-1</sup>. The ash produced had a mean pH of 11.9, and mean calcium carbonate equivalence of 52%. Lifting litter increased the density of fronds, and burning litter increased the soil available Mg concentrations and Ca concentrations in the ash. Pta concentrations in fronds that emerged in reaction to harvesting were higher compared to those fronds first harvested at the same time.
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Marty, Dominique Videau Nicole. "Les Landes à fougère aigle (Pteridium aquilinum) des Pyrénées françaises une étude phytogéographique /." Lille 3 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376077589.
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Boabaid, Fabiana M. "Achados clínico-patológicos e métodos de controle da intoxicação por Pteridium (aquilinum) arachnoideum." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/171444.
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A infestação de pastagens por populações de Pteridium arachnoideum é um problema que afeta a pecuária, em diversas partes do mundo. Os efeitos deletérios da infestação pela planta sobre a bovinocultura são manifestados na forma de mortalidades e de redução das áreas de pastagens, assim como de perdas produtivas. Devido à importância dessas perdas na produção de bovinos, foi proposto o acompanhamento de uma propriedade do Rio Grande do Sul com problemas decorrentes da infestação pela planta em sua casuística e métodos de controle empregados. Adicionalmente, realizou-se teste da viabilidade de ovinos como ferramenta de controle biológico. Dos casos de intoxicação naturais acompanhados na propriedade, observou-se a ocorrência de quadro agudo de diátese hemorrágica e de quadro crônico de carcinomas do trato digestório superior. Observou-se que quando expostos a fatores predisponentes, como a introdução em áreas recentemente roçadas, os bovinos podem consumir altas doses da planta e assim desenvolver a enfermidade aguda em forma de surtos. Em diversos bovinos jovens com quadro de diátese hemorrágica, além das hemorragias disseminadas e infartos múltiplos, observou-se acentuado edema laríngeo, que cursava clinicamente com dispneia e estertores respiratórios característicos. Os carcinomas do trato digestório superior, apesar de menos frequentes, causaram expressivas perdas devido a mortalidades anuais de matrizes. A tentativa de controle pelo pastejo por ovinos não foi eficiente, devido ao consumo pouco expressivo na lotação praticada. Mortalidade de ovinos, no entanto, decorrente do consumo da planta não foi registrada. O método de combate à planta aplicado na propriedade combinava ou associava a roçagem em áreas densamente povoadas com o uso de herbicidas, nomeadamente metilsulfuron-metil e picloram, em todos os piquetes. A redução da cobertura da P. arachnoideum foi variada em diferentes piquetes; entretanto, possibilitou a recuperação de algumas áreas de pastejo.<br>The infestation of pastured areas by Pteridium arachnoideum populations has been a considerable and global problem to the livestock production. The deleterious effects of the plant infestation on cattle are manifested as animal mortality and pasture coverage reduction. Given the importance of P. arachnoideum in cattle production, it has been proposed to monitor a beef cattle farm in Rio Grande do Sul, to assess some of the losses associated with the plant consumption apart of the methods employed for controlling the plant. In addition, the viability of sheep’s grazing as a biological control tool was tested. Cases of natural poisoning observed in the farm included the acute form, known as hemorrhagic diathesis as well as the chronic form, consisting in digestive carcinomas. When cattle were exposed to any predisposing factor, such as being moved to newly mowed areas, it was noted that the amount of plant consumed can readily lead to an outbreak of acute poisoning. Several cases of hemorrhagic diathesis in young cattle went along with marked laryngeal edema, which was clinically manifested as dyspnea and roaring, in addition to the classic pathological changes of widespread hemorrhages and infarcts. Even though less frequent, carcinomas of the upper digestive tract caused significant losses, due to annual mortality of mature cows. The attempt through grazing by sheep wasn’t efficient to control P. aquilinum, due to the low consumption of the plant seen in the actual stocking. However, sheep mortality, by P. arachnoideum consumption was not recorded. The plant control method applied at the farm combined mowing of densely populated areas with herbicide applications, namely metilsulfuron-methyl and picloram, in all paddocks. The reduction of P. arachnoideum coverage was varied in different paddocks; however, allowed the recovery of some grazing areas.
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Santos, Bruno Jos? Martini. "Aspectos Cl?nicos e Patol?gicos da Intoxica??o Experimental por Pteridium arachnoideum (Dennstatiaceae) em Equinos. 2010." Universidade Federal Rural do Rio de Janeiro, 2010. https://tede.ufrrj.br/jspui/handle/tede/881.
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Previous issue date: 2010-02-10<br>The administration of the aerial parts of Pteridium arachnoideum during 15 to 57 days in
proportions that varied from 50 to 75% of the supplied grass (Pennicetum purpureum) mixed
with hay of bracken fern, caused in 3 of the 4 experimental horses, a clinical and pathological
picture that can be attributed to the thiaminases, one of the poisonous principles of the plant.
The clinical picture consisted, in a progressive way, apathy, lethargy, sleepiness, hyporrexia
with evolution to anorexia, reluctance in moving, increase of heart frequency, arrhythmia and
sternal decubitus passing to lateral decubitus. The decubitus lasted at the most 48 hours. In
this phase, the clinical signs previously observed got more intense; additionaly the animals
refused water, made attempts of getting up without success, made intense intermittent
peddling movements, followed by dyspnoea, had muscular tremors, tonic muscle spasms of
limbs, opistotonus, intense sweating and finally death. The electrocardiographic analysis
showed hydropericardium and myocardial failure in the last 48 hours before
death. Post-mortem and histopathological examinations did not show significant lesions,
unless congestion in various organs, indicating congestive heart failure. Clinical pathology
revealed, in relation to the blood count, in one of the three horses, anemia in the final part of
the experiment, and trombocitopenia in only two. No changes were seen in the leucograma.
Parallel to a fall of serous thiamine, an increase the pyruvic acid was seen in the three
animals. One of the experimental horses developed a taste for the fern, and the other two only
consumed the P. arachnoideum-grass mixture with addition of sugar.<br>A administra??o das partes a?reas de Pteridium arachnoideum durante per?odos de 15 a 57
dias na propor??o que variou de 50 a 75% da mistura com capim (Pennicetum purpureum)
fornecida, causou em 3 dos 4 equinos do experimento um quadro cl?nico-patol?gico que
pode ser atribu?do a tiaminase, um dos princ?pios t?xicos da planta. No quadro cl?nico foram
verificados de forma progressiva apatia, letargia, sonol?ncia, hiporrexia com evolu??o para
anorexia, relut?ncia em se movimentar, aumento da frequ?ncia card?aca, arritmia e finalmente
dec?bito esternal passando para o lateral. O dec?bito era de no m?ximo 48 horas. Nesta fase
os sinais cl?nicos anteriormente observados se intensificaram, os animais, recusavam ?gua,
faziam tentativas de se levantar sem sucesso, movimentos de pedalagem intensos
intermitentes, seguidos de dispn?ia, tremores musculares, espasmos musculares t?nicos dos
membros, opist?tono, sudorese intensa e finalmente morte. As an?lises eletrocardiogr?ficas
indicaram hidroperic?rdio e insufici?ncia mioc?rdica nas ultimas 48 horas antes da morte. Os
achados de necropsia e os exames histopatol?gicos n?o revelaram altera??es significativas, a
n?o ser congest?o em diversos ?rg?os e efus?es cavit?rias de colora??o amarelo ocre, o que
est? relacionado com insufici?ncia card?aca congestiva. A patologia cl?nica revelou, em
rela??o ao hemograma, em um dos tr?s animais, anemia na parte final do experimento, e em
dois equinos trombocitopenia. O leucograma n?o apresentou altera??es. Paralelamente a
queda da tiamina s?rica, foi verificado um aumento do ?cido pir?vico nos tr?s animais. Um
dos animais experimentais desenvolveu um gosto pela samambaia, os outros dois consumiram
a mistura de capim com feno de samambaia mediante o acr?scimo de a??car.
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Zhang, Xiaofeng. "Structural studies of lumazine synthases - thermostability, catalytic mechanism and molecular assembly /." Stockholm, 2005. http://diss.kib.ki.se/2006/91-7140-605-0/.
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Rashbrook, Vanessa Karin. "Interactions between ants, herbivorous insects and bracken (Pteridium aquilinum), a fern with extrafloral nectaries." Thesis, Rhodes University, 1989. http://hdl.handle.net/10962/d1002042.
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Bracken (Pteridium aquilinum) is a cosmopolitan species of fern which possesses extrafloral nectaries. A survey of the arthropod fauna associated with the plant throughout its range in South Africa identified the most widespread and damaging bracken herbivores and those species most likely to be influenced by ants visiting the extrafloral nectaries. Seventeen herbivorous arthropods were found to be definitely feeding on bracken and a further thirteen species with a less certain status were recorded. In addition, several species of ants were observed on the fronds and feeding at the extrafloral nectarie. On the basis of their widespread distribution and abundance, four bracken herbivores emerged as being particularly detrimental to the plant in South Africa. They were an eriophyid gall mite, a leafhopper and two moths. The biology of the two lepidopterans, Appana cinisigna and Panotima sp., suggested that they were potentially vulnerable to ants at various stages of their life histories. Laboratory experiments were undertaken to observe ant-lepidopteran interactions under controlled conditions. The ant Crematogaster peringueyi rapidly removed exposed A. cini igna eggs, but did not appear to regard Panotima eggs as food items. Small instar larvae of both species proved vulnerable, but the larger larvae appeared capable of escaping ant predation. Ant exclusion experiments in the field, using natural and artificially augmented ant densities, were carried out at two sites near Grahamstown. The dominant ant species was C. peringueyi. Neither the numbers of lepidopterans nor levels of herbivory were significantly reduced by the presence of ants . Despite the implications of the laboratory tests, the results of these field experiments did not support the hypothesis that ants which visit bracken extrafloral nectaries benefit the plant. Ant-bracken field studies on other continents also reported no significant ant-related effects, though marginal reductions in the abundance of certain herbivores have been noted at one site in the U.K. Since ant protection does not appear to be an inevitable consequence of having extrafloral nectaries, their value to bracken is in some doubt. The most likely situation where effective protection will occur is when high densities of vulnerable herbivores are preyed upon by large numbers of aggressive ants. However, even under these conditions, enhancement of plant fitness is not inevitable. This raises the question of why extrafloral nectaries have been retained in a plant that is as successful and widespread as bracken.
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LANNA, NETA A. T. "Selênio como suplemento para bovinos intoxicados cronicamente por Pteridium sp. no Espirito Santo. 2017." Universidade Federal do Espírito Santo, 2018. http://repositorio.ufes.br/handle/10/7808.
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Previous issue date: 2018-01-09<br>Pteridiumsp.(samambaia) é uma planta responsável por diversos quadros de intoxicação em animais e seres humanos. Em bovinos, um dos quadros comuns na região sul do Espírito Santo é a hematúria enzoótica bovina (HEB) que não possui tratamento. Assim, o objetivo do presente trabalho foi determinar os efeitos do selênio associado a vitamina E como suplemento em animais intoxicados cronicamente pelo Pteridium sp. Foram selecionados 21 animais intoxicados cronicamente pela planta e com HEB. Os animais foram examinados clinicamente e foi realizada a coleta da urina para a confirmação da hematúria. O delineamento experimental foi feito em quatro grupos divididos ao acaso (controle soro fisiológico; tratamento 1 0,05 mg/Kg do suplemento;tratamento20,10mg/Kgdosuplemento;tratamento30,20mg/Kgdo suplemento). Foi feita a suplementação parenteral, via intramuscular, uma vez por semana, durante 13 semanas. Quinzenalmente os animais foram avaliados clinicamente e foram coletadas amostras de sangue para dosagem do selêniosérico. A análise de selênio foi feita nos momentos inicial, antes da suplementação com selênio (M0), após quatro semanas de tratamento (M4), após oito semanas (M8) e após 12 semanas (M12), pelo método de espectrofotometria de absorção atômica. Utilizou-seaanálisedevariância(ANOVA)seguidadotestedeTukeya5%.Verificou-se que houve maior ganho de peso dos animais tratados com selênio em relação ao grupocontrolee,também,entreosgrupos.Aintensidadedahematúriareduziuapartir da sexta semana e houve diferença significativa entre os grupos tratados e o grupo controle, assim como entre os grupos. Houve diferença significativa da concentração sérica de selênio entre os tratamentos. Assim, conclui-se que o selênio associado a vitaminaEcomosuplementoparabovinosintoxicadoscronicamenteporPteridiumsp. no Espirito Santo com quadro de HEB teve efeito dose dependente sobre a melhora doquadroclínicocausandoreduçãodaintensidadedehematúriaeaumentodoganho de peso
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Zhao, Jiewen. "The extraction of high value chemicals from heather (Calluna vulgaris) and bracken (Pteridium aquilinum)." Thesis, University of York, 2011. http://etheses.whiterose.ac.uk/2019/.
Texte intégralRésumé :
The aim of the project is to extract and identify high value chemicals with potential applications as pharmaceutical drugs or precursors from heather (Calluna vulgaris) and bracken (Pteridium aquilinum). Supercritical carbon dioxide extracts of heather were analysed for their triterpenoid content. Several triterpenoids were identified in heather supercritical carbon dioxide extracts and many of them were already reported to have potential valuable biological activities. Seasonal variation of total triterpenoid content in heather was also evaluated. The result indicated that summer flowering heather contains the highest concentration of total triterpenoid (15400 ug/g dry plant) and spring heather picked in March exhibited the second highest total triterpenoid content (11200 ug/g dry plant). Optimal harvest and extraction time of heather is also identified based on its triterpenoid seasonal variation trend. In this study, supercritical carbon dioxide extraction of bracken was achieved for the first time. Naturally occurring pterosin B and pterosin F were identified in bracken supercritical CO2 extract and the seasonal variation in pterosin content and other major compounds in bracken were also evaluated. Bracken crozier was found to contain the highest content of pterosins, and the pterosin content reduced dramatically when the frond grew towards its maturity. Geographical difference was also found to cause significant variation in the level of pterosins. It was found that Welsh bracken contains much less pterosin B and pterosin F compared to the Yorkshire sample. This distinct difference may be due to different pH value of the soil in Kilburn (Yorkshire) and Wales. Pterosins were recently proved to have strong anti-diabetic and anti-obesity activities. Although pterosin B and F were not identified to have certain anti-diabetic or anti-obesity activities in previous research, these pterosins, especially pterosin F, have high possibility to be used as precursors to other more effective pterosins because of its active chlorinated side chain.
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Oliveira, Lu?s Gustavo Picorelli de. "Novos Aspectos Patol?gicos e Patogen?ticos da Hemat?ria Enzo?tica Bovina." Universidade Federal Rural do Rio de Janeiro, 2009. https://tede.ufrrj.br/jspui/handle/tede/921.
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Previous issue date: 2009-01-28<br>Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior<br>Ninety bovine bladders, from a slaughterhouse from the district of Barra Mansa/RJ and from bovine necropsies in Pteridium arachnoideum invaded locations, were examined when associated with clinical signs as those found in bovine enzootic hematuria. A diffuse wrinkling of the bladder mucosa was found in 40% of the cases which was correlated to increased mucous normal irregularity, polyp proliferation, lamina propria thickening, fibrose and, in severe cases, urotelial carcinoma multicentric proliferation of endophitic growth. Papillary tumours were microscopically classified as urotelial carcinoma in 35% of cases and papiloma in 65%. In some cases, carcinoma and adenocarcinoma presented less commom differentiation patterns as intestinal, of Paneth cells, and a mesonefroid adenocarcinoma in the trigone area, which demonstrated bladder embryological origin influence on different types of lesions that were found. Mucosal hemorrhagic lesions occurred in 100% of the cases and were associated with vascular proliferation and lamina propria hemorrhage or, in sever cases, 77,4% of hemorrhagic elevations were correlated to hemangioma or hemangiosarcoma. At last, we have established a correlation between P. arachnoideum chronic poisoning lesions and ionizing radiation bladder alteration in humans.<br>Em um frigor?fico no munic?pio de Barra Mansa, RJ, e por ocasi?o de visitas a campo em regi?es infestadas pela Pteridium arachnoideum, foram coletadas 90 bexigas de bovinos que apresentavam sinais cl?nicos e ou les?es macrosc?picas compat?veis com o quadro de hemat?ria enzo?tica. As les?es encontradas tanto ao exame macrosc?pico quanto microsc?pico foram mais frequentes no corpo e na base da bexiga. ? macroscopia um enrugamento difuso da mucosa da bexiga foi observado em 40% dos casos, o que foi correlacionado ao aumento do pregueamento da mucosa, ? prolifera??o de p?lipos, ao espessamento da l?mina pr?pria, ? fibrose e, nos casos mais graves, ? prolifera??o multic?ntrica de carcinomas uroteliais com crescimento endof?tico. Tumores papiliformes foram classificados microscopicamente como carcinomas uroteliais em 35% dos casos e papilomas em 65%. Carcinomas e adenocarcinomas apresentaram, em alguns casos, diferencia??es consideradas pouco frequentes, como intestinal, em c?lulas de Paneth e em c?lulas claras. Um adenocarcinoma mesonefr?ide foi encontrado na posi??o do tr?gono, o que demonstra a influ?ncia da origem embriol?gica da bexiga sobre os tipos de les?es encontradas. Les?es hemorr?gicas na mucosa ocorreram em 100% dos casos, e estavam correlacionados a prolifera??es vasculares e hemorragias na l?mina pr?pria ou, nos casos mais graves, 77,4% das eleva??es hemorr?gicas foram correlacionadas a hemangiomas ou a hemangiossarcomas. Foi estabelecida uma identidade entre as les?es produzidas pela intoxica??o cr?nica por P. arachnoideum em bovinos e as altera??es provocadas na bexiga de seres humanos expostos a radioterapia ou ? radia??o ionizante ambiental.
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Masuda, Eduardo Kenji. "Patogênese dos carcinomas de células escamosas alimentares associados ao consumo de Pteridium aquilinum em bovinos." Universidade Federal de Santa Maria, 2010. http://repositorio.ufsm.br/handle/1/4051.
Texte intégralRésumé :
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>It is believed that papilloma formation is critical to pathogenesis of the upper digestive tract (UDT) squamous
cell carcinomas (SCCs) in cattle, the so called papilloma-carcinoma syndrome. Due to the maintenance of
papillomas for long periods of time in the UDT, due to immunosuppressive agents in bracken fern (Pteridium
aquilinum), the keratinocytes of papilloma become target for carcinogens to promote carcinomatous
transformation. Many evidences of the papilloma-carcinoma syndrome were observed in vitro. However, they
have not been totally proved in vivo. The objectives of this study were therefore to assess key aspects of the
pathogenesis of SCCs of the UDT in cattle naturally grazing in Pteridium aquilinum for long periods of time.
For this, 168 initial epithelial lesions of the UDT were evaluated in 60 cattle with alimentary SCCs from areas
with bracken fern. Developed papillomas had yielded more than 50% of the studied papillomas, with some in the
growing phase (18.5%) and some carcinomatous transformation of papillomas (18.5%). A few papillomas were
in regression (9%). The carcinomatous transformation of papillomas may represent morphological evidence of
the need for papilloma formation in the development of alimentary SCCs. However, 72 squamous intraepithelial
lesions (SILs) were also present in these bovines. Most SILs (70%) were moderate to severe dysplastic lesions
and carcinomas in situ, with a significant amount of SCCs in an early stage of development. In humans, similar
lesions are found in patients who chronically abuse of alcohol/tobacco. The SILs in the aerodigestive tract of
humans are potentially malignant and can evolve to SCCs. The SILs of cattle in this study may therefore
represent an alternative pathway for the development of SCCs in the UDT, without the necessity of
carcinomatous transformation of papilloma to SCCs. The papillomatous origin of alimentary SCCs was also
assessed by immunohistochemistry. Thirty SCCs of the cranial region of the UDT (including the base of tongue,
pharynx/oropharynx and epiglottis) were evaluated about the acinar or ductal salivary origin using an anticytokeratin
7/8 antibody specific for simple epithelium. From the 30 SCCs examined, nine had morphological
evidences of neoplastic transformation from a salivary duct. One of them was confirmed by
immunohistochemistry to be of salivary origin. As papillomavirus requires a stratified epithelium for the
formation of the papilloma, a confirmative SCCs from a simple salivary duct suggests that there is also no need
of a papilloma to the development of SCCs of the UDT in cattle chronically grazing on bracken fern. In parallel,
the degree of immunosuppression by lymphopenia, supposedly necessary for the maintenance of papillomas in
the UDT, was evaluated in spontaneous cases of SCCs in the UDT of cattle. Alimentary papillomatosis was
observed in all 40 cases studied. However, immunosuppression by lymphopenia was uncommon (three cases)
and was not related to the degree of papillomatosis. The absence of lymphopenia in cattle with alimentary
papillomatosis indicates that the mechanisms for maintenance of papilloma are not related to the amount of
circulating lymphocytes. In conclusion, this study demonstrated an alternative route for the pathogenesis of
SCCs in the UDT of cattle chronically poisoned by bracken fern and that the alimentary papillomatosis,
observed in such cases, is not associated with lymphopenia.<br>Segundo a teoria da patogênese da síndrome papiloma-carcinoma, a formação do papiloma é o ponto crucial
para o desenvolvimento dos carcinomas de células escamosas (CCEs) no trato alimentar superior (TAS) de
bovinos. A partir da sua manutenção por longos períodos no TAS, devido aos imunossupressores presentes na
samambaia (Pteridium aquilinum), os ceratinócitos do papiloma em constante multiplicação se tornariam alvos
para os carcinógenos da planta promoverem a transformação carcinomatosa. Muitas evidências da síndrome
papiloma-carcinoma foram observadas in vitro. No entanto, elas ainda não foram totalmente comprovadas in
vivo. Os objetivos deste estudo foram, portanto, avaliar aspectos fundamentais da patogênese da formação dos
CCEs no TAS em bovinos que pastoreiam naturalmente por longos períodos áreas altamente infestadas por
Pteridium aquilinum. Para isso, 168 lesões epiteliais iniciais foram avaliadas no TAS de 60 bovinos com CCEs
alimentares provenientes de áreas com samambaia. Papilomas desenvolvidos perfizeram mais de 50% dos
papilomas estudados, com alguns em crescimento (18,5%), em transformação carcinomatosa (18,5%) e poucos
em regressão (9%). A transformação carcinomatosa de papilomas pode representar a evidência morfológica da
necessidade do papiloma para a formação de CCEs. No entanto, 72 lesões intra-epiteliais escamosas (SILs)
também estavam presentes no TAS desses bovinos. A maior parte das SILs (70%) representava lesões
displásicas moderadas, acentuadas e CCEs in situ, com quantidade significativa de CCEs em estágio inicial. Em
humanos, lesões semelhantes estão presentes em pacientes que abusam cronicamente do álcool/tabaco. As SILs
no trato aerodigestivo de humanos são potencialmente malignas e podem evoluir para CCEs. As SILs nos
bovinos do presente estudo podem, portanto, representar uma via alternativa de formação de CCEs no TAS, sem
a necessidade da transformação do papiloma em carcinoma. A necessidade do papiloma para a formação de
CCEs alimentares em bovinos também foi avaliada através da imuno-histoquímica. Trinta CCEs da região
cranial do TAS (incluindo base da lingual, faringe/orofaringe e epiglote) foram avaliados quanto à origem acinar
ou ductal salivar utilizando-se o anticorpo anti-citoceratinas 7/8 para epitélio simples. Dos 30 CCEs analisados,
nove tinham evidências morfológicas de transformação neoplásica proveniente de ducto salivar. Destes, um foi
confirmado pela imuno-histoquímica. Como o papilomavírus necessita de estratificação epitelial para a formação
do papiloma, a confirmação de CCE de origem ductal salivar simples sugere que também não haja a necessidade
do papiloma para o desenvolvimento de CCEs no TAS de bovinos que pastoreiam em samambaia.
Paralelamente, o grau de imunossupressão por linfopenia, supostamente necessária para a manutenção dos
papilomas, também foi avaliada nos casos espontâneos de CCE no TAS de bovinos de áreas com samambaia.
Papilomatose alimentar foi observada em todos os 40 casos estudados. No entanto, imunossupressão por
linfopenia foi incomum (três casos) e não estava relacionada com o grau de papilomatose. A ausência de
linfopenia em bovinos com papilomatose alimentar indica que os mecanismos para a manutenção dos papilomas
não estejam relacionados com a quantidade de linfócitos circulantes. Em conclusão, o presente estudo
demonstrou haver uma via alternativa para a patogênese dos CCEs do TAS de bovinos intoxicados cronicamente
por samambaia e que a papilomatose alimentar, vista nesses casos, não está associada com linfopenia.
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Gabriel, Adriane Loy. "Aspectos epidemiológicos, clínicos e lesões vesicais na intoxicação crônica espontânea por Pteridium aquilinum em bovinos." Universidade Federal de Santa Maria, 2008. http://repositorio.ufsm.br/handle/1/10028.
Texte intégralRésumé :
Conselho Nacional de Desenvolvimento Científico e Tecnológico<br>Spontaneous cases of chronic poisoning by Pteridium aquilinum in cattle were studied. The clinical
forms of the disease were squamous cell carcinoma (SCCs) of the upper digestive tract (UDT) and bovine
enzootic hematuria (BEH). The cases were from the midland Region of the Midwest of Rio Grande do Sul State,
Brazil. For the epidemiological study, the profile of the farms was analyzed about herd purpose, main activity of
the farm, altitude, and area of plant infestation. No differences were observed among the clinical forms,
according to these criteria. Analysis of the ager, gender, and breed of the affected cattle revealed that, in both
clinical forms of disease, mixed breed cows (more common in that region) were more affected. In BEH, adult
cattle (3-to-7-years-old) were more frequently affected. In the form of UDT SCCs, aged cattle (more than 8-
years-old) were more affected. For the clinical study, clinical signs and blood work were evaluated at terminal
phase of disease. Cattle with UDT SCCs, had progressive weigth loss, ruminal atony, cough, dysphagia,
bloating, and regurgitation. Hematuria was clinically observed in one case of this disease form. In cattle with
BEH, hematuria was observed in all cases, followed by progresive weigth loss. Non-regenerative anemia was
detected in 33.33% in UDT SCCs form and in 66.66% of BEH form. Changes in white blood count occurred in
some cases but drop in lymphocytes was uncommon in both forms of disease. For the morfological study,
urinary bladders of 46 UDT SCCs cases and 11 BEH cases were analyzed. Grossly, 16/46 bladders of the UDT
SCCs form had gross lesions (vesical red or pale nodules, hemorrhages, and papilomas; red urine in the three
cases). In BEH form, the bladder had nodules, large neoplastic masses, red urine, papilomas, and hemorrhages.
Pielonephritis and hidronephosis were seen in a few cases. Microscopically, in the UDT SCCs form, 44/46
(95.65%) bladders had 22 different types of morphological changes, caracterized by neoplastic lesions (5/22) and
non-neoplastic lesions (17/22), which were subdivided in non-neoplastic epithelial changes (6/17), general
changes of the lamina propria (6/17), and inflammatory changes (5/17). The bladder changes in BEH form were
of 19 different types, caracterized by neoplastic lesions (5/19) and non-neoplastic lesions (14/19), which were
subdivided in non-neoplastic epitelial changes (9/14), general changes of the lamina propria (3/14), and
inflammatory changes (2/14). In BEH, mesenchymal neoplasms were more observed than epithelial ones, and
most of them were malignant. Immunohistochemistry was utilized to characterize the histogenesis of poorly
differentiated neoplasms. In conclusion, the morfological study showed that urinary bladder lesions are very
often in cattle with the UDT SCCs form, and were identical to the ones seen in cattle with BEH.<br>Foram estudados casos espontâneos de intoxicação crônica por samambaia em bovinos nas formas
clinicopatológicas de carcinoma de células escamosas (CCE) no trato alimentar superior (TAS) e de hematúria
enzoótica bovina (HEB), provenientes da Mesorregião Centro Ocidental do Rio-Grandense e encaminhados ao
Laboratório de Patologia Veterinária (LPV) da Universidade Federal de Santa Maria (UFSM). Para o estudo
epidemiológico, foi avaliado o perfil das propriedades quanto à finalidade da criação, principal atividade da
propriedade, altitude e área de infestação pela planta. Quanto a esses parâmetros, as propriedades com uma ou
outra forma de intoxicação crônica não apresentaram diferenças. Foi determinado o perfil dos bovinos afetados
quanto à idade, sexo e raça. Os mais afetados por ambas as formas clínicas foram fêmeas de raça mista
(predominante na região). Na HEB houve predomínio de bovinos adultos (três a sete anos) e a forma de CCEs no
TAS afetou mais bovinos idosos (mais de oito anos). Para o estudo clínico foram avaliados os sinais clínicos de
bovinos com CCEs no TAS e com HEB e realizados hemogramas na fase terminal da doença. Os principais
sinais clínicos nos bovinos com CCEs no TAS foram emagrecimento progressivo, atonia ruminal, tosse, disfagia,
timpanismo, regurgitação e hematúria, vista em um caso. Nos bovinos com HEB, hematúria foi o principal sinal,
observado em todos os casos, seguido de emagrecimento progressivo. No exame hematológico, 33,33% dos
bovinos com CCEs no TAS e 66,67% dos bovinos com HEB apresentaram anemia arregenerativa. Alterações no
leucograma ocorreram em alguns casos, mas linfopenia foi um achado infreqüente em ambas as formas de
intoxicação. Para o estudo morfológico, foram avaliadas as bexigas de 46 casos de CCEs no TAS e de 11 casos
de HEB. Macroscopicamente, 16/46 bexigas dos casos de CCEs no TAS apresentaram alterações macroscópicas,
que foram nódulos vermelhos ou pálidos, hemorragia e papilomas; urina vermelha foi observada em três casos.
Nos casos de HEB, os achados macroscópicos vesicais foram nódulos vermelhos, massas neoplásicas focalmente
extensas, urina vermelha, papilomas, hemorragias e ruptura de bexiga; pielonefrite e hidronefrose foram
observados em poucos casos. Histologicamente, 44/46 (95,65%) bexigas de bovinos com CCEs no TAS
apresentaram 22 tipos diferentes de alterações morfológicas, que foram classificadas em alterações neoplásicas
(5/22) e alterações não-neoplásicas (17/22), as quais foram divididas em alterações epiteliais não-neoplásicas
(6/17), alterações gerais na lâmina própria (6/22) e alterações inflamatórias (5/17). Os achados histológicos das
bexigas dos casos de HEB foram classificados da mesma forma, resultando em 19 tipos diferentes de alterações
morfológicas. Dessas, 5/19 eram alterações neoplásicas e 14/19, alterações não-neoplásicas (9/14 alterações
epiteliais não neoplásicas, 3/14 alterações gerais na lâmina própria e 2/14 alterações inflamatórias). Na HEB, os
neoplasmas mesenquimais foram mais observados que os epiteliais, e a maior parte era maligno. A técnica de
imuno-histoquímica foi utilizada para caracterizar os aspectos morfológicos, principalmente dos neoplasmas.
Através do estudo morfológico concluiu-se que é muito freqüente a ocorrência de lesões vesicais em bovinos
com a forma crônica de CCEs no TAS e que essas são idênticas às encontradas nos bovinos com HEB.
43
Souto, Marione de Albuquerque Moreira. "NEOPLASIAS DO TRATO ALIMENTAR SUPERIOR EM BOVINOS ASSOCIADAS AO CONSUMO ESPONTÂNEO DE SAMAMBAIA (Pteridium aquilinum)." Universidade Federal de Santa Maria, 2005. http://repositorio.ufsm.br/handle/1/10056.
Texte intégralRésumé :
Thirty bovine with neoplasms of the upper digestive tract (UDT) associated to the spontaneous consumption of
bracken fern (Pteridium aquilinum) were studied. They were from 27 farms, localized in the municipalities of Jaguari (23) and Nova Esperança do Sul (4), Rio Grande do Sul, Brazil. The total bovine population in those farms was 1,090 and large amounts of bracken fern were found in the pastures. Twenty-six were cows e four were castrated males. The age ranged from 3 to 13-years-old. Most of them were 7 to 8-years-old (46,6%). Clinical signs observed in the affected animals were progressive weight loss, absence of ruminal movements, cough, dysphagia, regurgitation, halitosis, diarrhea, and bloat. Less frequent signs were selective appetite, dyspnea, and salivation. Two bovines died and 28 were euthanatized in extremis and submitted to necropsy. The main gross and microscopic findings were found in the same areas of the UDT. They were digestive papillomatosis, transforming papillomas, and squamous cell carcinomas (SCC). Twenty-nine bovines had papillomas of various sizes in several areas of the UDT. The digestive papillomatosis ranged from mild (45%), to moderate (38%), to severe (17%). Three developing phases were observed microscopically in the examined papillomas: an early growing phase, a developing phase, and a regressing phase. The regressing phase was characterized by lymphocytic infiltrates at the base of the papilloma. In 16 cases, the microscopic examination of lesions grossly resembling papillomas (although some were slightly round, with lower or ulcerated finger-like projections) revealed malignant transformation of the papillomas into SCCs. The SCCs were solitary (12/30) or multiple (18/30) and were histologicaly characterized as well, moderately, or poorly differentiated. Grouping the distribution of SCCs of larger extension in the UDT into cranial region (base of the tongue, pharynx/oropharynx, and epiglottis), medial region (esophagus), and caudal region (cardia and rumen), the distribution was cranial in 39%, middle in 16%, and caudal in 45% of the cases. By the same grouping criteria, but considering the total number of times SCCs of varied extensions were diagnosed in the cranial, middle, and caudal regions, the percentages changed to 34%, 26%, and 40%, respectively. Metastases to regional lymph nodes and other organs, like liver and lungs, were observed in 18 cases. Immunohistochemistry for cytokeratin was performed in selected sections of SCCs and metastases, showing strong positive reaction in the well and moderately differentiated SCCs, but weak positive reaction in the poorly differentiated ones. The epidemiological and histomorphological evidences showed in this study are in agreement with the observations that point out the co-carcinogesis between bovine papillomavirus type 4 infection and chemicals of bracken fern in the pathogenesis of the SCCs in the UDT of cattle.<br>Foram estudados 30 bovinos com neoplasias no trato alimentar superior (TAS) associadas ao consumo
espontâneo de samambaia (Pteridium aquilinum) provenientes de 27 propriedades rurais, sendo 23 no município de Jaguari e quatro em Nova Esperança de Sul, Rio Grande do Sul. A população bovina total das 27 propriedades em que ocorreram os casos era de 1.090 bovinos e havia quantidade abundante de samambaia nas áreas de pastoreio dos animais. Vinte e seis bovinos eram vacas e quatro eram machos castrados. A idade variou de três a 13 anos, sendo o maior número de casos entre sete e oito anos (46,6%). Os sinais clínicos observados incluíram emagrecimento progressivo, atonia ruminal, tosse, disfagia, regurgitação, halitose, diarréia e
timpanismo. Outros sinais clínicos menos freqüentes foram apetite seletivo, dispnéia e salivação. Dois bovinos tiveram morte espontânea e 28 foram submetidos à eutanásia in extremis e necropsiados. Os principais achados macroscópicos e histológicos observados nos 30 bovinos localizavam-se nos mesmos locais do TAS e consistiam de papilomas, papilomas em transformação para carcinomas de células escamosas (CCEs) e CCEs. Vinte e nove bovinos tinham papilomas de diversos tamanhos, sendo a quantidade variável entre leve (45%), moderada (38%) e acentuada (17%). Nos papilomas examinados microscopicamente, foram observadas três
fases de desenvolvimento: a) fase inicial de crescimento; b) fase de desenvolvimento; e c) fase de regressão; essa
última era caracterizada por infiltrados linfocitários nos eixos fibrovasculares de sustentação. Em 16 bovinos, o exame histológico de lesões macroscópicas compatíveis com papilomas, porém alguns deles apresentando-se mais arredondados, com projeções digitiformes atenuadas ou ulceradas, revelou a transformação maligna desses papilomas em CCEs. Os CCEs eram únicos (12/30) ou múltiplos (18/30) e variaram quanto ao grau de diferenciação celular entre bem diferenciados, moderadamente diferenciados ou pouco diferenciados. Quando a distribuição dos CCEs de maior extensão foi agrupada em regiões cranial (base da língua, faringe/orofaringe, epiglote), média (terços cranial, médio e caudal do esôfago) e caudal (entrada do rúmen e rúmen) do TAS, observou-se que a localização era cranial em 39% dos casos, média em 16%, e caudal em 45%. Utilizando-se
esse mesmo critério de agrupamento, porém considerando o número total de vezes em que CCEs (de extensões variadas) foram diagnosticados nas regiões cranial, média e caudal, os números alteraram-se para 34%, 26% e 40%, respectivamente. Metástases de CCEs para linfonodos regionais e outros órgãos como fígado e pulmão foram observadas em 18/30 bovinos. A técnica de imunoistoquímica para citoqueratina foi realizada em cortes selecionados de CCEs e metástases, observando-se células fortemente positivas nos CCEs bem e moderadamente diferenciados, e fraca imunomarcação nos pouco diferenciados. As evidências epidemiológicas e histomorfológicas relatadas neste estudo reforçam as observações de uma estreita correlação entre a infecção pelo papilomavírus bovino tipo 4, causador da papilomatose digestiva, e a co-carcinogênese química dos
princípios tóxicos da samambaia na patogênese dos CCEs do TAS de bovinos.
44
Costa, Danilo C?sar de Abreu. "Avalia??o de controle de Pteridium aquilinum (l.) Kuhn. na RPPN Fartura em Capelinha, MG." UFVJM, 2016. http://acervo.ufvjm.edu.br/jspui/handle/1/1090.
Texte intégralRésumé :
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Previous issue date: 2016<br>Companhia Energ?tica de Minas Gerais (Cemig)<br>Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)<br>A Reserva Particular do Patrim?nio Natural (RPPN) Fartura possui ?rea de 1,5 mil ha, dos quais aproximadamente 40 se encontram dominados por Pteridium aquilinum (samambaia). Esta esp?cie est? oferecendo grande risco a biodiversidade do local, visto que a mesma apresenta elevado potencial invasor e capacidade de competi??o, podendo inibir a regenera??o natural e atrasar a sucess?o por s?culos. Diante disso, objetivou-se com este trabalho definir t?cnicas de controle populacional de Pteridium aquilinum e induzir a regenera??o natural, assim como avaliar a resposta de algumas esp?cies de r?pido crescimento submetidas a doses crescentes de calc?rio, com potencial para serem utilizadas na restaura??o desta ?rea. O primeiro estudo foi desenvolvido em uma ?rea dominada por samambaia, utilizando delineamento em blocos casualizados arranjado em esquema fatorial 3 x 2, consistindo em tr?s t?cnicas de controle (ro?ada mecanizada, glyphosate e paraquat), removendo ou n?o a serrapilheira das parcelas. Foram alocadas parcelas de 10 x 10 m distribu?das em 3 blocos. Ap?s seis meses, foram avaliados a porcentagem de cobertura de samambaia e de radia??o fotossinteticamente ativa (RFA) incidente sobre o solo, assim como o n?mero de indiv?duos regenerantes e a diversidade para cada tratamento. Os resultados indicaram que o controle qu?mico, tanto por glyphosate quanto por paraquat, promoveu maior redu??o de samambaia e que a remo??o da serrapilheira favoreceu o ingresso de indiv?duos e o aumento da diversidade. O segundo estudo foi realizado em casa de vegeta??o, na Universidade Federal dos Vales do Jequitinhonha e Mucuri - UFVJM, em delineamento em blocos casualizados com 3 repeti??es. Os tratamentos consistiram em elevar a satura??o por bases do substrato a 50, 70 e 90%, al?m do tratamento controle (sem corre??o). O substrato utilizado foi coletado na ?rea do primeiro estudo com o m?ximo de ra?zes de samambaia, corrigido com a quantidade de calc?rio determinada para cada tratamento e distribu?do em vasos de 10 dm?, onde as mudas de quatro esp?cies arb?reas foram plantadas. As esp?cies utilizadas foram: Anadenanthera colubrina (angico), Enterolobium contortisiliquum (orelha de macaco), Inga sessilis (ing?) e platycyamus regnelii (pau pereira). As vari?veis avaliadas foram di?metro e altura das mudas e a massa seca de samambaia. As esp?cies angico e orelha de macaco se mostraram sens?veis ? acidez do solo, sendo responsivas ao aumento da satura??o por bases. J? as esp?cies ing? e pau pereira s?o mais tolerantes ?s condi??es de acidez do solo, por?m, tamb?m obtiveram melhor desenvolvimento com a calagem. A samambaia apresentou aumento da massa seca com a eleva??o da satura??o por bases, mostrando que a calagem n?o ? uma pr?tica adequada para o controle dessa esp?cie.<br>Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Ci?ncia Florestal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, [2016].<br>The Private Reserve of Natural Heritage (RPPN) Fartura has 1500 ha area of which approximately 40 are dominated by Pteridium aquilinum (bracken). This specie is offering great risk to the biodiversity of the site, since it has a high invasive potential and competitive ability and can inhibit natural regeneration and delay the succession for centuries. Therefore the aim of this study was to define techniques for promoting Pteridium aquilinum population control and induce natural regeneration, as well as to evaluate the response of some fast growing species exposed to increasing doses of limestone with potential to be used in the restoration of this area. The first study was conducted in an area dominated by bracken, using a randomized block design arranged in a factorial 3 x 2. It consisted of three control techniques (mechanized mowing, glyphosate and paraquat), removing or not litter from the plots. They were allocated 10 x 10 m plots into 3 blocks. After six months the bracken coverage percentage and photosynthetically active radiation (PAR) incident on the ground were evaluated,, as well as the number of regenerating individuals and diversity for each treatment. The results indicated that the chemical control both glyphosate as paraquat promoted greater reduction of bracken and the removal of litter favored the entry of individuals and increased diversity. The second study was conducted in a greenhouse at Federal University of Vales do Jequitinhonha and Mucuri - UFVJM under a randomized block design with three replications. The treatments consisted of raising the base saturation of the substrate 50, 70 and 90% beyond the control treatment (no correction). The substrate used was collected in the first study area with maximum bracken roots, corrected by the amount of certain limestone for each treatment and distributed in pots of 10 dm?, where the seedlings of four tree species were planted: Anadenanthera colubrina (angico), Enterolobium contortisiliquum (orelha de macaco), Inga sessilis (ing?) Platycyamus regnelii (pau pereira). The variables were diameter and seedling height and dry mass of bracken. The angico species and orelha de macaco were sensitive to soil acidity, being responsive to the increase in base saturation. The species ing? and pau pereira are more tolerant to soil acidity conditions, but they also had better development with liming. Bracken showed an increase in dry matter with increasing base saturation, showing that liming is not an appropriate practice for controlling these species.
45
Freitas, Renata Nascimento de. "Estudos moleculares de tecidos normais e tumores malignos de roedores tratados com samambaia (Pteridium aquilinum)." Universidade Federal de Minas Gerais, 2001. http://hdl.handle.net/1843/UCSD-8HEPNW.
Texte intégralRésumé :
Bracken fern (Pteridium aquilinum) toxicity and carcinogenicity properties have been extensively described in domestic and experimental animals. Some epidemiologic studies have associated the human exposition to the bracken fern and /or to its toxins with a higher risk for the occurrence of esophagus cancer in Venezuela and stomach cancer in Japan, Brazil, Costa Rica, United Kingdom ad Venezuela. However, these epidemiologic studies are not enough to unequivocally establish a causal relationship between bracken fern and cancer development in human beings. In the present work we proposed to investigate the presence of molecular markers of the bracken fern toxins on the animals genome which, if found, would be used in the assessment of the risk to the bracken exposure for humans. Initially, we investigated DNA adducts formation in normal targets tissues of female rats treated by gavage with a single dose of alcoholic extracts or other different preparations obtained from young fronds of freshly collected bracken for medium and long term. We used 32P-postlabeling method to identify the DNA adducts. Our results indicate that DNA adducts detectable by 32P-postlabeling are not formed in stomach or ileum of rats treated with bracken fern via digestive tube. We evaluate the presence of adducts in DNA samples obtained from upper digestive tube of mice treated with an acute single dose of bracken extract and spores and we found three adducts that had been previously described and also other four adducts which were not characterized. None of these adducts presented chromatography mobility similar to the single adduct obtained from in vitro modified DNA with activated ptaquiloside (a carcinogenic glycoside extracted from bracken). We conclude that other substances, besides ptaquiloside, are able to induce DNA adducts formation, which might contribute to the bracken carcinogenicity in mice. Following the strategy to identify molecular markers of the bracken action in the rat genome, and considering colorectal tumors carcinogenesis in humans as model, we examined eight malignant tumors induced by bracken treatment in rats for the presence of mutations in genes related to the classical pathway for the colorectal cancer, p53 and ras and also evaluated the mutator pathway by studying microsatellites stability. The exons 5 9 of the p53 and exons 1 and 2 of the K-ras and H-ras genes were sequenced and none mutation was found in the eight tumors. The amplification of five microsatellites loci previously validated (one mononucleotide repeat, three dinucleotide repeat and one tetranucleotide repeat) in the malignant tumors and in normal adjacent tissue did not reveal any microsatellite instability. The envolvement of mutations occurring in other tumor suppressor genes or oncogenes of the classical pathway as well as in genes required for chromosomal segregation and epigenetic events still must be investigated in the search for molecular markers of the bracken fern induced tumors.<br>As propriedades tóxicas e carcinogênicas da samambaia (Pteridium aquilinum) têm sido extensivamente descritas em animais domésticos e experimentais. Alguns estudos epidemiológicos têm associado a exposição humana à samambaia e/ou suas toxinas com um aumento do risco de ocorrência de câncer de esôfago e estômago no Japão, Brasil, Costa Rica, Reino Unido e Venezuela. No entanto, estes estudos epidemiológicos não são suficientes para, inequivocadamente, estabelecer uma relação causal entre a samambaia e o surgimento destes cânceres em humanos. Assim, propusemo-nos no presente trabalho, a investigar a presença de marcadores moleculares da ação das toxinas da samambaia sobre o genoma de animais que, se encontrados, pudessem ser utilizados na avaliação do risco da exposição à samambaia para humanos. Investigamos inicialmente a formação de adutos de DNA em tecidos alvos normais de ratas tratadas via intragástrica com uma dose aguda única de extratos alcoólicos obtidos do broto de samambaia ou com diferentes preparações de broto de samambaia por médios e longos prazos. Utilizamos a metodologia de pós-marcação com 32P para identificação de adutos de DNA. Nossos resultados indicam que adutos de DNA detectáveis por pós-marcação com 32P não são formados em estômago e íleo de ratas tratadas com broto de samambaia via digestiva. Avaliamos a presença de adutos em amostras de DNA de tubos digestivos superior de camundongos tratados com dose aguda de extrato e esporos de samambaia e encontramos três adutos que já haviam sido descritos e ainda outros quatro adutos que não foram caracterizados. Nenhum destes adutos apresentou mobilidade cromatográfica similar ao único aduto obtido de DNA modificado in vitro com o ptaquilosídeo ativado (glicosídeo carcinogênico extraído da samambaia). Assim, concluímos que outras substâncias presentes na samambaia, além do ptaquilosídeo, são capazes de induzir a formação de adutos de DNA, podendo contribuir para a carcinogenicidade da samambaia em camundongos. Como parte da estratégia para identificação de marcadores moleculares da ação da samambaia sobre o genoma de ratos, e usando a carcinogênese de tumores colorretais humanos como modelo, examinamos oito tumores malignos induzidos pela samambaia em ratos para a presença de mutações nos genes associados com a via clássica para o câncer colorretal, p53 e ras e também avaliamos a via mutadora estudando microssatélites. Os exons 5 9 do gene p53 e os exons 1 e 2 dos genes K-ras e H-ras foram examinados por seqüenciamento de DNA e nenhuma mutação foi encontrada nos oito tumores malignos. A amplificação de cinco locos de microssatélites previamente validados (um com repetição de mononucleotídeo, três com repetições de dinucleotídeos e um com repetições de tetranucleotídeos) nos tumores malignos e em tecido normal adjacente não revelou qualquer instabilidade. O envolvimento de mutações em outros genes supressores de tumor ou oncogenes da via clássica bem como em genes requeridos para a segregação cromossômica e eventos epigenéticos devem ser ainda investigados na pesquisa por marcadores moleculares de tumores induzidos pela samambaia.
46
Hinshalwood, A. M. "Factors influencing the absorption, translocation and biochemical action of asulam in bracken (Pteridium aquilinum (L.) Kuhn)." Thesis, University of Strathclyde, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372086.
Texte intégral
47
Der, Joshua P. "Genomic Perspectives on Evolution in Bracken Fern." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/663.
Texte intégralRésumé :
The fern genus Pteridium comprises a number of closely related species distributed throughout the world. Collectively they are called bracken ferns and have historically been treated as a single species, Pteridium aquilinum. Bracken is notorious as a toxic weed that colonizes open fields and poisons livestock. Bracken is also easily cultured and has become one of the most intensively studied ferns. Bracken has been used as a model system for the study of the fern life cycle, fern gametophyte development, the pheromonal mechanism of sex determination, toxicology, invasion ecology, and climate change. This dissertation places bracken within a global evolutionary perspective and establishes bracken as an emerging system for evolutionary genomics in ferns. Bracken samples from around the world were examined for chloroplast DNA variation to infer historical phylogenetic and biogeographic evolutionary events. New high-throughput DNA sequencing technologies and bioinformatic approaches were used to determine the complete chloroplast genome sequence in bracken, to identify novel RNA editing sites in chloroplast transcripts, and to identify gene sequences that are expressed in the gametophyte stage of the fern life cycle. These data represent an important genomic resource in ferns and were examined within a functional and evolutionary perspective. Several novel approaches and analyses were developed in the course of this research. Results presented in this dissertation provide novel insights into fern biology and land plant evolution.
48
Sheaves, Barbara Joan. "An investigation of certain human health problems associated with bracken fern (Pteridium aquilinum) environments in the U.K." Thesis, University of Plymouth, 1995. http://hdl.handle.net/10026.1/2228.
Texte intégralRésumé :
Bracken environments harbour the sheep tick (Ixodes ricinus), known vector of a number of diseases. Initial investigation indicated the presence of sheep ticks infected with the Lyme disease spirochaete Borrelia burgdorferi on open moorland areas of the North York Moors and the moorland areas of the South West of the U.K. Some aspects of the problem of Lyme disease on U.K. moorlands were explored in this study. A survey through the summer of 1993 of people using the North York Moors, Dartmoor and the Quantock Hills in Somerset for both work and leisure activities revealed a very high proportion of people (76% of respondents had not heard of Lyme disease) who were unaware of the risk of Lyme disease or of how they might reduce that risk. An examination of three moorland vegetation communities as optimal tick habitats suggested that immature ticks are less dense on heather dominated communities than on either bracken or on Vaccinium dominated communities, and that this may be influenced by the fauna using heather dominated areas. Vaccinium sites showed high densities of all life stages of the sheep tick, as did bracken dominated sites. Ticks were collected throughout the winter months on South Western sites, but not on the North York Moors, emphasising the year round risk from infected ticks in the South West of the U.K. Vegetation management practices as tick control or reduction options in these moorland areas were investigated. Asulam spraying on bracken almost totally removed the above ground frond cover, substantially reduced live buds on the rhizome, but failed to reduce the rhizome dry weight. The density of frond cover was not affected by cutting, height and dry frond weight were reduced, live rhizome buds reduced in number and rhizome dry weight reduced. Short term control of bracken fronds was achieved by both treatments, but neither treatment provided sufficiently conclusive results on which to base long term recommendations. Comprehensive plans for after care on treated sites need to be in place before treatment is carried out. Tick densities were recorded over a two year period on these treated bracken sites. There was a proportional reduction in all tick life stages between 1993 and 1994 on sites sprayed with asulam and on cut sites compared with control sites. Although not statistically significant these results suggested that the methods of bracken control investigated in this study could influence sheep tick densities in the short term.
49
Whitehead, Sharon J. "The morphology and physiology of moorland bracken (Pteridium aquilinum (L.) Kuhn) and their implications for its control." Thesis, University of York, 1993. http://etheses.whiterose.ac.uk/2506/.
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Jubrael, J. M. S. "Preparation of a partial gene library, detection of DNA polymorphisms and chromosome studies in the fern Pteridium." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377748.
Texte intégral