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1
Widestrand, Johan. « Assessment of trichothecene contamination : chemical aspects and biological methodology / ». Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-5808-0.pdf.
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Marsh, David C. « Chemical and biochemical transformations of trichothecene mycotoxins ». Thesis, University of Nottingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235967.
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Asam, Stefan. « Analytik von Trichothecen-Mykotoxinen ». Garching DFA, 2009. http://d-nb.info/994911408/04.
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Lévy, Philippe. « La vomitoxine ». Strasbourg 1, 1990. http://www.theses.fr/1990STR15014.
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Hesketh, Andrew R. « Metabolic studies on the transformation of trichodiene to trichothecene mycotoxins ». Thesis, University of Nottingham, 1991. http://eprints.nottingham.ac.uk/12521/.
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Trichodiene and [14C]trichodiene have been produced in high yields by treatment of Fusarium culmorum CMI 14764 cultures with the furanocoumarin xanthotoxin. Smaller amounts of isotrichodermin (ITD) and the unsubstituted trichothecene 12,13-epoxytrichothec-9-ene (EPT) were obtained in the same way. EPT was also produced by semi-synthesis from ITD. Trichodiene (TDN) was shown to be a precursor of the trichothecene mycotoxins in F. culmorum, including EPT, ITD, calonectrin (CAL), 7a-hydroxycalonectrin (7-hydroxyCAL), 15-deacetylcalonectrin, 3-acetyldeoxynivalenol (3-AcDON) and 7,8-dihydroxycalonectrin (DHC). When large amounts of TDN were supplied, a new trichodiene metabolite was found to accumulate which was fully characterised as 12,13-epoxy-2a, 11 adihydroxytrichodiene, and given the trivial name isotrichodiol. A method for the production of 14C-labelled isotrichodiol (ITdiol) was developed, and the incorporation of ["C]ITdiol into 3-AcDON, DHC and 7-hydroxyCAL was demonstrated. Slow, acid-catalysed cyclisation of ITdiol to EPT and pre-sambucoin was demonstrated, and allylic isomerisation to both 9a- and 9p-trichodiol was also detected. Labelled pre-sambucoin was incorporated into sambucoin by F. culmorwn, and ITdiol is thus proposed as a precursor to both sambucoin and sambucinol, aswel as to the trichothecenes. A range of semi-synthetic derivatives of TDN were prepared and tested as possible inhibitors of the post-TDN biosynthesic pathway to trichothecenes in F. culmorum. In whole-cell systems all the derivatives inhibited the incorporation of labelled TDN into trichothecenes, and also initiated the production of ITdiol. One derivative, 9P, 10ß-epoxytrichodiene, was shown to be biotransformed by the fungus, undergoing 12,13-epoxidation with subsequent hydroxylation at C-3 producing 3a-hydroxy-9(3,10(3; 12,13-diepoxytrichodiene. 9ß-Trichodiol was isolated from Trichothecium roseum, and its slow, acidcatalysed cyclisation to EPT was demonstrated. 9a-Trichotriol, 9ß-trichotriol and isotrichotriol were isolated from F. culmorum for the first time, and literature assignments for the stereochemistry of the C-9 hydroxyl in trichodiol and trichotriol are reassessed. The incorporation of [`4C]ITdiol into trichothecenes in F. culmorum was found to be approximately 5 times greater than the incorporation of [14C]-913-trichotriol, and was shown to be inhibited by isotrichotriol but not by 9ß-trichodiol and 9ß-trichotriol. It is proposed that trichodiol and trichotriol are not biosynthetic intermediates in the pathway to the trichothecenes, and that they are non-enzymic metabolites produced from ITdiol and isotrichotriol, respectively, by acid-catalysed isomerisations. A new scheme for the biosynthesis of trichothecenes is proposed in which ITdiol and isotrichotriol are intermediates in the production of isotrichodermol from TDN. Two novel compounds, 15-deacetyl-7,8-dihydroxycalonectrin (15-deacetylDHC) and 8a-hydroxyisotrichodiol were isolated from F. culmorum, and 15-deacetylDHC and DHC were shown to be precursors to 3-AcDON. It is proposed that the post-cyclisation biosynthesis of 3-AcDON involves sequential oxygenation of isotrichodermol at C-15, C-7 and C-8 producing DHC, which then undergoes deacylation to 15-deacetylDHC followed by oxidation at C-8 to 3-AcDON.
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Ward, Caroline L. « Chemical and biochemical studies on the biosynthesis of trichothecene mycotoxins ». Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263003.
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Kim, Yongcheol. « Ribosomal protein gene expression and trichothecene resistance in Arabidopsis thaliana / ». The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487687115927105.
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Janse, Van Rensburg Daniel Francois. « The biological properties of three trichothecene mycotoxins produces by fusaris ». Master's thesis, University of Cape Town, 1986. http://hdl.handle.net/11427/27209.
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The highly toxic fungal metabolite, neosolaniol monoacetate, was isolated and purified from cultures of Fusarium sambucinum. Since little is known about its toxic properties, the biological effects of this trichothecene were compared to those caused by diacetoxy-scirpenol in male Wistar rats. The lesions caused by the two toxins were very similar. Chronic exposure to either toxin led to a significant decrease (P<0.05) in red blood cell counts and a significant increase (P<0.05) in platelet size. The major pathological lesions observed were atrophy of the actively dividing cells of the bone marrow, thymus, spleen and lymph nodes. The reported species difference in T-2 toxin toxicity was investigated by determining the deacylation rate of T-2 toxin to HT-2 toxin, one of the first steps in the detoxification of this trichothecene. The high deacylation rate catalysed by rat microsomes correlated with the low sensitivity of this species to T-2 toxin, whereas the low deacylation rates with cat and monkey microsomes agreed with their high sensitivity. In contrast to this, the apparently high toxicity of T-2 toxin to humans does not correlate with the high deacylation rate observed in human hepatic microsomes. Involvement of the UDP-glucuronyltransferases in the detoxification of T-2 toxin was studied with rat and pig hepatic microsomes. T-2 toxin and two of its metabolites, HT-2 toxin and T-2 tetraol, did not appear to act as substrates for these enzymes under the in vitro conditions used.
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Tag, Andrew George. « Characterization of the Tri10 gene from Fusarium sporotrichioides ». [College Station, Tex. : Texas A&M University, 2003. http://hdl.handle.net/1969.1/64.
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Thesis (Ph.D.)--Texas A&M University, 2003."Major Subject: Plant Pathology" Title from author supplied metadata (record created on Jul. 18, 2005.) Vita. Abstract. Includes bibliographical references.
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Schnerr, Helge. « Quantitativer Nachweis von Deoxynivalenol und Trichothecene-bildenden Fusarium spp. mit Biosensor und PCR in Getreide ». [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965200639.
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Khatibi, Piyum. « Reduction of the mycotoxin deoxynivalenol in barley ethanol co-products using trichothecene 3-O-acetyltransferases ». Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/28361.
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The fungal plant pathogen Fusarium graminearum Schwabe (teleomorph Gibberella zeae¬) produces a dangerous trichothecene mycotoxin called deoxynivalenol (DON) and causes a devastating disease of barley (Hordeum vulgare L.) called Fusarium head blight (FHB). Food and feed products derived from barley, such as dried distillers grains with solubles (DDGS), may be contaminated with DON and pose a threat to the health of humans and domestic animals. New methods to mitigate the threat of DON in barley need to be developed and implemented. TRI101 and TRI201 are trichothecene 3-O-acetyltransferases that modify DON and reduce its toxicity. The first objective of this research was to isolate unique TRI101 and TRI201 enzymes that modify DON efficiently. We hypothesized that TRI101/TRI201 enzymes from different species of Fusarium would have varying rates and abilities to modify DON. Using degenerate primers, an internal portion of TRI101 or TRI201 was identified in 54 strains of Fusarium. Full-length sequences of seven TRI101 or TRI201 genes were cloned and expressed in yeast. All seven genes acetylated DON, but at different rates. The second objective of this research was to utilize transformed yeast expressing TRI101 or TRI201 to reduce DON levels in barley mashes and ultimately in DDGS. We hypothesized that DON levels would be reduced in DDGS derived from mashes prepared with transformed yeast. Five different barley genotypes were used to prepare the fermentation mashes and DON levels were reduced in all DDGS samples derived from mashes prepared with transformed yeast. The third objective of this study was to characterize barley genotypes developed at Virginia Tech for resistance to FHB and DON. We hypothesized that significant differences in resistance would be observed among barley genotypes and FHB resistance would be associated with reduced DON accumulation. From 2006 to 2010, FHB resistance was assessed in hulled (22 to 37) and hulless (13 to 32) barley genotypes by measuring incidence and index, and DON resistance was determined by quantifying DON levels in ground grain using gas chromatography-mass spectrometry. Our study showed that FHB and DON resistance is significantly determined by genotype. The final objective of this study was to develop a robust tissue culture system necessary for future development of transformed barley plants with FHB resistance gene(s). We hypothesized that callus production would vary among barley genotypes. In our analysis of 47 Virginia barley genotypes, 76% (36/47) of the genotypes produced callus tissue and there were significant differences in callus size. Our work sets the stage for identifying and characterizing DON detoxification genes in the future. The development of commercial barley lines that do not accumulate DON and that are resistant to FHB will directly impact growers and producers of small grains in the eastern U.S.Ph. D.
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Zhao, Hui. « Inhibition of Fusarium Growth and Trichothecene Accumulation in Grain by Antifungal Compounds from Lactic Acid Bacteria ». Diss., North Dakota State University, 2013. https://hdl.handle.net/10365/26870.
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Fusarium head blight (FHB) is a widely occurring plant disease, which is caused by fungi in the genus Fusarium. FHB leads to mycotoxin accumulation on grain, which causes food safety risk and economic loss. In addition to chemical treatments, biological strategies, like application of lactic acid bacteria (LAB), could be useful in preventing and/or eradicating mycotoxigenic Fusarium growth and mycotoxin production.After comparision of the anti-Fusarium activities by a microdilution assay against Fusarium graminearum 08/RG/BF/51, Lactobacillus rhamnosus VT1 was found to have the highest anti-Fusarium activity. Response surface methodology (RSM) was employed to optimize the incubation conditions for the production of cell-free Lactobacillus culture supernatant (CFLCS) from the strain. The best combination included 34??C, 55 hours, and shaking at 170 rpm for production of CFLCS from L. rhamnosus VT1. Under these incubation conditions, a 10% cell-free culture of Lactobacillus rhamnosus VT1 inhibited 83.7% of the Fusarium growth on microplate. MIC value of the CFLCS with a 10
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Reinbrecht, Carsten. « Genetische und physiologische Einflußfaktoren sowie deren Wechselwirkungen auf die Trichothecenbildung bei Roggen, Triticale und Weizen nach Inokulation mit Fusarium culmorum (W. G. Sm.) Sacc ». [S.l. : s.n.], 2002. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10316342.
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Chami, Amarasinghe. « The continuing battle between wheat and Fusarium graminearum : understanding the molecular phylogenetic relationships, chemotype diversity and trichothecene biosynthesis gene expression patterns ». John Wiley and Sons- Plant Pathology, 2015. http://hdl.handle.net/1993/31596.
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Fusarium head blight (FHB) continues to threaten the economic sustainability of wheat and barley production in Canada and worldwide. The overall goal of this thesis is to expand our current knowledge of the FHB pathogen, Fusarium graminearum and its trichothecene chemotype diversity. Continuous monitoring of trichothecene chemotypes may well inform on the potential risk and the type of Fusarium populations present in a given region. Fusarium populations in Winnipeg and Carman, Manitoba were examined using chemotype as a marker in the field. Rapid expansion of the 3-acetyldeoxynivalenol (3-ADON) chemotype was observed in Winnipeg and Carman. 3-ADON chemotype is consistently found at high frequencies over the previously common 15-acetyldeoxynivalenol (15-ADON) chemotype, suggesting that the shift in pathogen populations is continuing. This study provides the first evidence on the presence of nivalenol (NIV) producing F. cerealis strains in winter wheat in Manitoba, Canada. Therefore, discovery of NIV producing F. cerealis in wheat poses a serious concern for the wheat industry in Canada. Phylogenetic, chemotypic, phenotypic, and pathogenic abilities of 150 strains of F. graminearum species complex (FGSC) from eight countries were investigated. Type and amount of trichothecenes produced by a strain are key factors in determining the level of aggressiveness of that strain regardless of its species origin. The sequence variations of TRI8 gene in different species in the FGSC were examined as Fusarium species may produce different types of trichothecenes depending on differences in the core trichothecene (TRI) cluster genes. The TRI8 haplotypes did group according to chemotype rather than by species, indicating that 3-ADON, 15-ADON and NIV chemotypes have a single evolutionary origin. Comparison of TRI gene expression demonstrated that accumulation of TRI transcripts was higher in 3-ADON producing strains compared to 15-ADON and NIV strains. The presence of masked mycotoxins deoxynivalenol-3-glucoside (D3G) in food and feed is an increasing concern. Canadian spring wheat cultivars inoculated with different chemotypes produce D3G upon Fusarium infection and moderately resistant/intermediate cultivars showed higher D3G/DON ratio compared to susceptible cultivars.October 2016
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Wang, Huiyan. « Toxicity and signaling mechanisms underlying interactions of Stachybotrys chartarum toxins with lung macrophages ». University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1319487821.
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Piacenza, Nicolo Alessandro [Verfasser], et Manfred [Akademischer Betreuer] Gareis. « Upcycling of mycotoxin contaminated grains to food : The Yellow Mealworm (Tenebrio molitor), a safe utilizer of trichothecene-contaminated oats ? / Nicolo Alessandro Piacenza ; Betreuer : Manfred Gareis ». München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2021. http://d-nb.info/122983575X/34.
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Herman, David. « Metody extrakce vybraných toxinů z pevných matric a jejich následné stanovení pomocí HPLC/MS ». Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2014. http://www.nusl.cz/ntk/nusl-217012.
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This diploma thesis is focused on the analysis of toxins and their extraction from sandyloamy soil. Particularly, saxitoxin and trichothecene mycotoxins deoxynivalenol, HT-2 and T-2 toxins are in the centre of interest of this work. Their occurrence, toxic properties and influence on living organisms are described in theoretical part of this thesis. In next chapters, currently published extraction methods for individual toxins and analytical approaches for their quantitative evaluation are summarized. In experimental part of this thesis, optimized process of sample pretreatment based on extraction of toxins from soil using 1mM HCOONH4 in 84% acetonitrile was proposed as the best option. Simultaneous determination of toxins was performed by liquid chromatography on a CN column (3.0 x 150 mm, 3 m, 100 ) in gradient elution mode. Mass spectrometer with electrospray as ion source and linear ion trap as analyzer was used as detector. Recovery of designed method was over 80% for trichothecene mycotoxins and 51% for saxitoxin.
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Merhej, Jawad. « Mécanismes moléculaires contrôlant la biosynthèse de mycotoxines par le champignon micromycète Fusarium graminearum ». Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14198/document.
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Fusarium graminearum est un champignon filamenteux qui parasite les plantes céréalières et le maïs et provoque la fusariose de l’épi. Durant l’infection, ce champignon produit des mycotoxines de la famille des trichothécènes qui s’accumulent dans les grains. Les processus de décontamination existants ne permettent pas d’éliminer complètement les trichothécènes. Ainsi, le meilleur moyen pour éviter leur accumulation dans les grains serait de pouvoir limiter leur occurrence au champ en contrôlant leur biosynthèse. Bien que la voie de biosynthèse des trichothécènes et les gènes Tri qui y sont impliqués soient bien décrits, les connaissances de base sur les mécanismes de régulation de ces gènes restent trop restreintes.Dans la première partie de ce travail, l’effet du pH sur la régulation des gènes Tri et la production de trichothécène a été étudié. En premier lieu, nous avons démontré que, in vitro, un pH acide joue le rôle d’inducteur alors qu’un pH neutre ou alcalin bloque l’expression des gènes Tri et la production de trichothécène. Ensuite, FgPac1, l’homologue du gène pacC/RIM101 codant le facteur de régulation par le pH chez les champignons a été identifié dans le génome de F. graminearum. A l’aide de souches recombinantes, nous avons démontré que la forme mature de ce facteur réprime l’expression des gènes Tri à pH acide et réduit la virulence du champignon lors de l’infection d’épis de blé. Enfin, le transcriptome de F. graminearum en réponse au pH et le rôle de Pac1 dans cette réponse a été analysé.Dans la deuxième partie de ce travail, le gène velvet sensible à la lumière, a été identifié chez F. graminearum. Ce gène constitue la composante clef d’un complexe qui coordonne la perception de la lumière avec le développement mais aussi avec le métabolisme secondaire chez les champignons. L’inactivation de FgVe1 chez F. graminearum nous a permis de démontrer son rôle dans le développement et la production de spores. Elle a montré aussi que ce gène est nécessaire pour permettre l’expression des gènes Tri, la production de trichothécène et la pathogénicité in planta.L’ensemble de ce travail permet de mieux comprendre la régulation de la production de trichothécène chez F. graminearum et ouvre des perspectives qui permettront sans doute, à long terme, d’élaborer des stratégies de lutte contre l’accumulation de trichothécène au champThe filamentous fungus Fusarium graminearum infects cereals plants and corn and causes “Fusarium Head Blight”. During infection, it produces mycotoxins belonging to trichothecenes family which accumulate in the grains. The available decontamination processes do not fully eliminate the trichothecene. Hence, the best way to avoid their occurrence in the grains is to limit their accumulation in the field by controlling their biosynthesis. Although the Tri genes implicated in the trichothecene biosynthetic pathway are well described, the basic knowledge regarding their regulation is still too limited.In the first part of this work, the effect of the pH on Tri genes regulation and trichothecene production was studied. First, we demonstrated that, in vitro, acidic pH acts as an inducer while a neutral or alkaline pH blocks Tri genes expression and trichothecene production. Then, FgPac1, the homologue of the pacC/RIM101 gene encoding the fungal pH regulatory factor was identified. Using recombinant strains, we demonstrated that the mature form of this factor represses Tri gene expression at acidic pH and reduces virulence during infection of wheat spikes. Finally, we analyzed the transcriptome of F. graminearum in response to pH and investigated the role of Pac1 in this response.In the second part of this work, the light-responsive velvet gene was identified in F. graminearum. This gene is the key component of a complex coordinating light perception with development and secondary metabolism in fungi. The disruption of FgVe1 in F. graminearum demonstrated its role in development and spores production. It also showed that this gene is necessary for Tri gene expression, trichothecene production and pathogenicity in planta.Overall, this work allows a better understanding of trichothecene regulation in F. graminearum and provides novel perspectives to develop new strategies against trichothecene accumulation during cereal growing in the field
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Cumagun, Christian Joseph R. « Molecular and phenotypic analyses of pathogenicity, aggressiveness, mycotoxin production, and colonization in the wheat-Gibberella zeae pathosystem ». [S.l. : s.n.], 2004. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11163838.
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Hrdinová, Lucie. « Sledování obsahu vybraných trichothecenových mykotoxinů ve sladovnickém ječmeni ». Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-216628.
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This master thesis deals with a monitoring of a content of the trichothecene mycotoxins deoxynivalenol, nivalenol, T-2 toxin and HT-2 toxin in malting barley using the LC-MS/MS method. The theoretical part describes general characteristics of mycotoxins and their significant producer filamentous fungus of Fusarium species. Further, important trichothecene mycotoxins and mycotoxins generally which are commonly found in malting barley were also characterized. In the theoretical part of the thesis possibilities for a determination of the mycotoxins by the chromatographic methods were presented too; the immunochemical methods were also mentioned. In the experimental section an analysis of the B type trichothecenes was optimized by LC/APCI-MS/MS and of the A type trichothecenes by LC/ESI-MS/MS. When analyzing 57 samples of different barley varieties the deoxynivalenol reached the highest values (up to 945,2 µg.kg-1), namely in the case of the Sebastian variety with corn as the fore-crop. The highest values of nivalenol, T-2 toxin and HT-2 toxin (138,4 µg.kg-1; 21,8 µg.kg-1 and 68,7 µg.kg-1 respectively) were found in the Prestige variety of barley with winter wheat as the fore-crop. Subsequently a second set of four experimental samples of the Sebastian variety of barley and malt produced from the variety with corn as the fore-crop were analysed. In this group three samples were artificially infected with the filamentous fungi of Fusarium species; the fourth sample was not artificially infected and served as a control sample. Even in the case of the artificially infected samples the deoxynivalenol reached the highest values. The master thesis was implemented in the Research Institute of Brewing and Malting, Plc. in Brno.
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Sundstøl, Eriksen Gunnar. « Metabolism and toxicity of trichothecenes / ». Uppsala : Dept. of Animal Nutrition and Management, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/a400.pdf.
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Cameron, Stuart. « Chemistry and interconversion of complex trichothecenes ». Thesis, University of Glasgow, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306079.
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Robbana-Barnat, Saïda. « Toxicite et pouvoir immunomodulateur de mycotoxines (desoxynivalenol, t-2 toxine) ». Paris 6, 1986. http://www.theses.fr/1986PA066597.
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Smith, Philip Harold. « Trichodiene synthase and the role of trichothecenes in Fusarium Spp ». Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301934.
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Brown, B. A. « Diels-Alder approaches towards T-2 toxin and related trichothecenes ». Thesis, University of Glasgow, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375448.
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Song, Zhongshu. « Biosynthesis of natural products in microorganisms : griseusin, fusarin C and trichothecenes ». Thesis, University of Bristol, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404084.
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Kearvell, Joan. « Reduction of T-2 toxic activity by enzymes from Fusarium oxysporum ». Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69524.
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Fusarium oxysporum grown on natural media was believed not to produce mycotoxins of the trichothecene family. Using a defined chemical medium toxin production was investigated for and it was found that trichothecenes were produced. A yeast bioassay using Kluyveromyces fragilis, an organiam sensitive to such trichothecenes as T-2 toxin and verrucarin, was used for detection of toxin in culture filtrates. Detectable levels of toxin (0.2 $ mu$g in litre of culture) were seen by day 4 and peaked around day 9 corresponding to maximum growth (measured by mycelial mass). After this time fluctuations in the level of toxin and growth became evident, suggesting a breakdown of the toxins by the organism for a carbon source. Search for an enzyme or enzyme system, capable of degrading T-2 toxin in snail gut enzyme digested F. oxysporum, was attempted using the esterase substrate para-nitrophenol acetate. Esterase activity was detected in all fractions including culture filtrate, soluble protein fraction and insoluble protein fraction, as well as solubilized insoluble proteins (digested by contents of the crude extract). The soluble protein fraction exhibited the highest level of activity. Cells digested with the detergent Lubrol followed by precipitation of the solubilized proteins with ammonium sulphate revealed the presence of an active component(s) in the high molecular weight portion of the soluble cell fraction collected at 50 and 75% saturation. Further purification by DEAE-sepharose failed to produce an active component.
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Dorfling, Sasha-Lee. « Enantioselective transformations using tetrol as a chiral mediator ». Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/d1021195.
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(+)-(2R,3R)-1,1,4,4-Tetraphenylbutane-1,2,3,4-tetraol (TETROL) and its derivatives were reacted with varying molar ratios of titanium isopropoxide (2:1, 1:1 and 1:2 tetraol:titanium isopropoxide) in an attempt to prepare potential titanium-based tetraol catalysts for enantioselective transformations. In each case, infrared and HNMR spectra suggested that the product was formed. We tentatively proposed that the structure of the catalyst was a spiro-type, but we could not determine conclusively what its exact structure was, despite using numerous techniques at our disposal (molecular modelling calculations, H NMR and IR spectroscopy, thermal analyses, powder diffraction, and single crystal X-ray diffraction). The catalyst and derivatives thereof were able to act catalytically for the enantioselective additions of diethylzinc compounds to aldehydes. The effects of temperature and solvent were investigated, and toluene and -78 °C were selected as optimal from the results obtained. (The reaction could, however, not be maintained at this low temperature for extended periods due to the fact that we did not have, at our disposal, the correct equipment. Each 16 h reaction was thus allowed to reach room temperature in each case.) The selectivity for the product 1-phenylpropan-1-ol (when benzaldehyde was the starting aldehyde) varied depending on the nature of the aryl substituents of the titanium-based catalyst. Using 0.2 molar equivalents of the chiral titanates, the highest selectivity was 42 percent (e.e.), but only when excess Ti(O-i-Pr)4 had been added to the reaction mixture. This was achieved with the tetra(ortho-methoxyphenyl)-TETROLate derivative. TETROL and its derivatives were also successful in metal-free catalysis where higher conversions and selectivities were observed, compared to when these were complexed to titanium. The highest selectivity was 70 percent (e.e.), achieved with the tetra(ortho-methylphenyl)TETROL derivative.
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Meneely, Julie Patricia. « Development and validation of rapid analytical techniques for the determination of trichothecine mycotoxins ». Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534609.
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Alassane-Kpembi, Imourana. « The intestinal toxicity of mycotoxins : analysis of the interactions between type B trichothecenes ». Thesis, Toulouse, INPT, 2013. http://www.theses.fr/2013INPT0115/document.
Texte intégralRésumé :
L'intestin est la première barrière de l'organisme contre les contaminants alimentaires, dont les mycotoxines. Le déoxynivalenol (DON) est un contaminant majeur des céréales, souvent retrouvé en association avec d'autres trichothécènes B (TCTs B), le 3- et 15-acétyldéoxynivalénol (3-ADON et 15-ADON), le nivalénol (NIV) et la fusarénone X (FX). Au niveau cellulaire, le DON interagit avec l'ARN ribosomique, bloquant ainsi la synthèse protéique et activant la cascade de la voie de signalisation de MAPKinases impliquée dans des mécanismes de la réponse inflammatoire. Au niveau intestinal, cette mycotoxine pourrait donc perturber le renouvellement continu de l'épithélium, et l'homéostasie de la réponse inflammatoire. On suggère ainsi qu'elle pourrait jouer un rôle dans la pathogénie des maladies inflammatoires chroniques de l'intestin. Si les effets du DON sont relativement connus, ceux du NIV et de leurs dérivés acétylés sont moins bien documentés. De même, peu de données existent quant à la toxicité combinée de ces mycotoxines dont la co-occurrence est avérée. Sur des modèles in vitro de cellules épithéliales intestinales humaines et porcines et sur un modèle ex vivo d'explants de jéjunum de porc, nous avons comparé les toxicités individuelles de cinq TCTs B (DON, 3- et 15-ADON, NIV et FX) et analysé leur toxicité combinée en termes de synergie, additivité ou antagonisme vis-à-vis de l'intestin. Les résultats montrent qu'à des concentrations de l'ordre du micromolaire, les TCTs B inhibent la croissance des cellules épithéliales intestinales par ordre croissant de toxicité 3-ADON, DON, 15-ADON, NIV et FX. Aux faibles doses correspondant à des niveaux d'exposition rencontrés chez le consommateur français ou européen, des synergies d'un facteur 3 à 10 ont été observées. Ces travaux ont également permis de caractériser l'activité pro-inflammatoire au niveau intestinal des TCTs B, et l'analyse benchmark de données de transcriptomique a montré que l'exposition de l'intestin à des doses aussi faibles que 0.04µM de FX, 0.1µM de DON ou 0.1µM de NIV s'accompagne d'une activation significative des mécanismes de l'inflammation. Ces doses sont de l'ordre des concentrations attendues dans le chyle sur la base des valeurs toxicologiques de référence actuelles. En conclusion, ces données montrent que le renouvellement de l'épithélium intestinal et l'activité pro-inflammatoire au niveau intestinal pourraient être des marqueurs très sensibles dans le cadre de l'évaluation de la toxicité individuelle et des interactions entre TCTs BAs for other food-born contaminants, the gastro-intestinal tract represents the first barrier against deoxynivalenol (DON). This mycotoxin frequently co-occurs with other type B trichothecenes (TCTs B) namely 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON), nivalenol (NIV) and fusarenon-X (FX). At the cellular level, DON binding to ribosomal RNA results in the inhibition of protein synthesis and triggers the mitogen-activated protein kinases (MAPKs) pathway that have been linked to immune response mechanisms. Thus, intestinal epithelial cell renewing is considered a putative target in DON toxicity. Moreover, based on the ability of DON to disturb the state of homeostasis of the inflammatory response in the intestine mimicking what is found in inflammatory bowel diseases (IBD), it is proposed that this mycotoxin may play a role in such diseases. However, very few is known about the intestinal toxicity of the other co-occuring TCT B, and their combined effects eventually. By means of in vitro human and porcine intestinal epithelial cells models and an ex vivo porcine jejunal explants model, we assessed the individual toxicity of five TCT B (DON, 3- and 15-ADON, NIV and FX) toward the intestine and we analyzed their combined toxicity in terms of additivity, synergy or antagonism. The tested TCT B significantly impaired the intestinal epithelial cell growth in the micromolar range, in increasing order of potency 3-ADON, DON, 15-ADON, NIV and FX. The toxicity of low doses of TCT B was synergistic. For mycotoxin concentrations corresponding to exposure levels reported for French and European consumers, the amplitude of this synergy ranged between 3 and 10. Benchmark dose analyses of the transcriptional data also showed that the exposure of the intestine to mycotoxin concentrations as low as 0.04µM for FX, 0.1µM for DON and 0.1µM for NIV could be associated to a significant activation of the inflammatory response mechanisms. Taken together, these results suggest that epithelial cell renewing and pro-inflammatory effects at the intestinal level may be consider very sensitive biomarkers for the assessment of the individual toxicity and interactions between the co-occurring TCTs B
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Tang, Ruoling. « Growth of Fusarium graminearum and Production of Trichothecenes During the Malting of Winter Rye and Triticale ». Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/31718.
Texte intégralRésumé :
There is growing interest in malting and brewing with rye. However, previous research has shown a propensity for the development of deoxynivalenol (DON) in rye malts, even when levels on the grain is low. The main objective of this study was to assess the growth of F. graminearum and development of trichothecenes during malting of rye. Infected samples were obtained from 2016 variety trails in Minnesota. While DON levels were generally below 0.2 mg/kg, an average increase of 41 % was seen after malting. The most significant increases in DON were at three days of germination. Fusarium Tri5 DNA levels were observed to increase at two days. When single kernels were tested, most were free from DON. Levels in the bulk grain sample were due to a small number of highly contaminated kernels. In the malted samples, a greater portion of kernels contained DON, and overall levels were much higher.
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Oliveira, Adriana Queiroz de. « Tricotecenos em milho : uma avaliação de metodos analiticos e da incidencia em milho pipoca ». [s.n.], 2001. http://repositorio.unicamp.br/jspui/handle/REPOSIP/254718.
Texte intégralRésumé :
Orientador: Lucia Maria Valente SoaresDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-07-27T08:21:17Z (GMT). No. of bitstreams: 1 Oliveira_AdrianaQueirozde_M.pdf: 4196208 bytes, checksum: 92d5a9097bf404e01a3739a01e11104f (MD5) Previous issue date: 2001
Resumo: Os tricotecenos são metabolitos secundarios produzidos por especies de Fusarium, Myrothecium, Cephalosporium, Verticimonosporium, Stachybotrys e trichothecium. Estas micotoxinas podem causar vômitos, angina becrótica, diarreia, anorexia, alterações hematológicas, distúrbios neurológicos, destruição da medula óssea e hemorragias generalizadas, seguidos ou não de morte
Abstract: The trichothecenes are secondary metabolites produced by species of Fusarium, Myrothecium, Cephalosporium, Verticimonosporium, Stachybotrys and Trichothecium. These mycotoxins can cause vomiting, angina becrótica, diarrhea, anorexia, haematological disorders, neurological disorders, destruction of bone marrow and widespread bleeding, followed or not the death
Mestrado
Mestre em Ciência de Alimentos
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SHAMSAZAR, JILA. « Synthese chimique et etude de composes de la serie des trichothecenes macrocycliques. Cas des myrotoxines et des satratoxines ». Paris 7, 1989. http://www.theses.fr/1989PA077249.
Texte intégralRésumé :
Ce memoire contient les resultats de recherches consacres a l'etude des analogues structuraux de trichothecenes macrocycliques qui possedent des proprietes biologiques, notamment antibiotiques et antitumorales. Deux representants de cette serie ont ete etudies, la myrotoxine et la satratoxine, plus particulierement leur partie macrocyclique qui est la partie comportant des differences structurales existant entre les divers representants de cette famille. La synthese de cette partie macrocyclique qui contient un cycle pyranne et deux esters insatures n'a jamais ete publiee. Ces syntheses ont ete elaborees a partir des structures glucidiques qui ont ete determinees d'apres une analyse retrosynthetique. L'etape importante de ce travail a consiste en la synthese du precurseur cle de tous les analogues. L'introduction ensuite du premier groupement ester sur le noyau pyrannique (partie commune aux deux molecules) a ete accomplie avec la geometrie desiree. Ainsi la preparation des divers sites pour l'introduction de second groupement ester a pu etre realisee dans de bonnes conditions. Au cours de ces travaux une nouvelle methode de blocage des hydroxyles a ete mise au point. Cette methode d'alkylation, donnant d'excellents rendements, qui necessite l'emploi d'halogenures d'alkyles en presence de potasse, est catalysee par l'ether couronne (18-cr-6). Une partie importante de ce memoire est consacree a la determination des structures des composes obtenus, notamment par l'etude des spectres rmn a l'aide d'un appareil de 300 mhz. Aussi, afin de supprimer toute mobilite conformationnelle, certains de ces produits ont du etre cyclises. Ainsi leurs geometries ont pu etre determinees avec exactitude et les tests biologiques effectues sur des molecules de structure bien definie. Ces tests preliminaires effectues sur des cellules lymphocytaires et des cellules tumorales daudi ont donne des res
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AHMAD, NURIE AHMAD. « Contribution a l'etude de la croissance et de la toxinogenese du genre fusarium (link) sur mais apres recolte ». Nantes, 1986. http://www.theses.fr/1986NANT2036.
Texte intégralRésumé :
La premiere partie des travaux a porte sur la mise au point des methodes permettant le dosage de cinq toxines du groupe des trichothecenes. Les methodes mises au point concernent les toxines responsables de contaminations naturelles; t2-toxine, ht2-toxine, t2-tetraol, diacetoxyscirpenol, deoxynivalenol. L'etude de modalites des biosyntheses de ces toxines a ete precedee de differents essais preliminaires: une trentaine de souches, appartenant a une dizaine d'especes fusariennes frequentes sur mais en france, ont ete examinees pour leur aptitude a la synthese des trichothecenes. Deux especes caracteristiques (f. Lateritium et f. Sporotrichioides) ont ete retenues et etudiees en detail
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Cheat, Sophal. « Individual and combined effects of the trichothecenes deoxynivalenol and nivalenol ex vivo and in vivo on pig intestinal mucosa ». Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30041/document.
Texte intégralRésumé :
Déoxynivalenol (DON) et nivalénol (NIV), fusariotoxines majeures des céréréales peuvent endommager l'intestin. Les effets de DON et NIV sur la muqueuse intestinale ont été étudiés chez le porc, après exposition aigüe d'explants jéjunaux après 4 heures (0 à 10 µM), d'anses jéjunales après 4 et 24 heures (0 à 10 µM), et après exposition d'animaux pendant 28 jours, à des aliments naturellement contaminés. Ex vivo sur les explants, des modifications histologiques dose-dépendantes ont été induites. In vivo, la diminution du nombre de cellules villositaires en prolifération a été concordante pour les anses jejunales et chez les animaux, atteignant, pour DON et NIV respectivement, 13 et 30% après 4h, et après 24 heures 35% et 40%, à 10 µM. Dans les anses, l'apoptose a été induite au niveau des villosités à 10µM de DON et de NIV. Après 24 heures, le nombre d'entérocytes apoptotiques a augmenté de façon dose dépendante avec DON, NIV, et DON+NIV (1:1), et l'analyse d'interaction a montré une synergie pour ce paramètreDeoxynivalenol (DON) and nivalenol (NIV), major fusariotoxins and worldwide cereal contaminants, raise concerns for intestinal health. The impact of DON and NIV on pig intestinal mucosa was investigated after acute exposure on jejunal explants after 4 hours (0 to 10 µM), on jejunal loops after 4 hours and 24 hours (0 to 10 µM), and after 28-day natural contamination feeding of animals. On explants, dose-dependent increases in the histological changes were induced. The decrease in the overall proliferative villus cells was concordant between animal experiment and loops, reaching after 4 hours in loops 13% and 30%, and after 24 hours 35 and 40 % for DON and NIV respectively, at 10 µM. In loops, villus apoptosis increased after DON and NIV at 10 µM. After 24 hours, apoptotic enterocytes increased dose-dependently by DON, NIV, or the combination DON+NIV (1:1). The interaction analysis showed synergism between DON and NIV for villus enterocyte apoptosis
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GANDOLFI, ISABELLE. « Rearrangements acido-catalyses de systemes 2-oxa-bicyclo(4. 2. 0) octanes. Contribution a la synthese d'analogues des trichothecenes ». Paris 11, 1993. http://www.theses.fr/1993PA112027.
Texte intégralRésumé :
Ce travail decrit les rearrangements acido-catalyses des systemes 2-oxa-bicyclo(4. 2. 0) octanes: contribution a la synthese des cycles pontes b/c des mycotoxines de type trichothecene telles que l'anguidine: 1) voie lactone: l'addition photochimique de l'acetylene sur la lactone 15 n'est pas stereospecifique. De ce fait, aucun rearrangement n'a ete tente sur le cyclobutenyl carbinol b; 2) voie enone: differents alcools tertiaires 48 et 49, possedant le systeme 2-oxa-bicyclo(4. 2. 0)octane ont ete synthetises. Leur stabilite en presence de bf#3-et#2o ou d'acide formique ne conduit pas, dans les conditions douces etudiees, a la formation du systeme ponte (3. 2. 1) octane cible; 3) la stabilite de ces unites 2-oxa-bicyclo(4. 2. 0)octanes a ete confirmee dans le cas du compose 69 en presence de bf#3-et#2o. La formation de l'isomere 73 a partir de 69 implique la rupture de la liaison centrale par un mecanisme de type retroaldolisation; 4) l'etude des effets conformationnels des differents composes synthetises en r. M. N. #1#3c montre que ce squelette 2-oxa-bicyclo(4. 2. 0) octene est flexible. A l'inverse, la stabilite du systeme sature correspondant est a associer aux plus faibles variations relevees des deplacements chimiques
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Tralamazza, Sabina Moser. « Diversidade fúngica, análise polifásica do gênero Fusarium e determinação de desoxinivalenol e zearalenona em grãos de trigo de diferentes regiões do Brasil ». Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/42/42132/tde-06102015-190949/.
Texte intégralRésumé :
O presente trabalho visou utilizar o perfil polifásico, envolvendo características fenotípicas e genotípicas, na identificação de Fusarium spp. isolados de grãos de trigo como também investigar a presença das principais toxinas: desoxinivalenol e zearalenona nos grãos de trigo de três regiões produtoras de trigo (São Paulo, Paraná e Rio Grande do Sul). Nossos resultados indicaram que os gêneros mais frequentes no trigo foram Alternaria, Fusarium e Epicoccum. A determinação do genótipo por qPCR demonstrou predomínio de 15-ADON seguido por NIV e 3-ADON. A quantificação de DNA demostrou que o perfil 15-ADON foi responsável por 96% de todo DNA quantificado, seguido por NIV com 3.84% e 3-ADON, com somente 0.06%, indicando que 15-ADON, é o principal genótipo de tricoteceno nos grãos de trigo nacional. A toxina desoxinivalenol foi detectada em todas amostras analisadas, com mediana de 323, 466 e 783 µg/kg em SP, PR e RS, respectivamente. A determinação de zearalenona demonstrou contaminação em 100%, 80% e 42% dos grãos dos Estados do RS, PR e SP e medianas de 843, 100 e 14 µg/kg, respectivamente.The present work aimed to use a polyphasic approach, by phenotypic and genotypic characteristics for the identification of Fusarium strains from wheat grains as well to investigate the presence of deoxynivalenol and zearalenone on wheat grains from three wheat producers States (Parana, Rio Grande do Sul and Sao Paulo). Our results showed that the main genera found were Alternaria, Fusarium and Epicoccum. Genotype detection from qPCR revealed predominance of 15-ADON, followed by NIV and 3-ADON. The qPCR demonstrated that 15-ADON genotype was responsible for 96% of all DNA quantified, followed by NIV with 3.84% and 3-ADON with 0.06%, indicating that 15-ADON is the main trichothecene genotype from Brazilian wheat grains. The toxin deoxynivalenol was detected in all 150 samples analyzed from wheat grains, with medians of 323, 466 and 783 µg/kg in SP, PR and RS, respectively. The zearalenone determination showed contamination on 100%, 80% and 42% of wheat grains from RS, PR and SP State and medians of 843, 100 and 14 µg/kg, respectively.
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Andretta, Ines. « Estudo meta-analítico das interações produtivas e nutricionais das micotoxinas na alimentação de suínos e frangos de corte ». Universidade Federal de Santa Maria, 2011. http://repositorio.ufsm.br/handle/1/10761.
Texte intégralRésumé :
Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorTwo studies were performed in order to evaluate, through meta-analysis, the relationship of mycotoxins with performance and organ weights in pigs and broilers. The databases totaled 13,196 pigs (85 articles published between 1968 and 2010) and 37,371 broilers (98 articles, between 1980 and 2009). Meta-analysis followed three sequential analyses: graphical, correlation and variance-covariance. Pigs challenged by mycotoxins reduced feed intake by 18% and weight gain by 21% in relation to the control group. Challenged broilers presented a reduction of 12% in feed intake and 14% in weight gain. Mycotoxins with the greatest impact on performance were deoxynivalenol and aflatoxins in pigs, and ochratoxins and aflatoxins in broilers. The mycotoxin concentration in diets and the animal age at challenge were the variables that more improved the coefficient of determination in equations for estimating the mycotoxin effect on weight gain. The mycotoxin effect on growth was greater in younger animals. In addition, the residual analysis demonstrated that the greater part of the variation in weight gain was explained by the variation in the feed intake (87% in pigs and 65% in broilers). The variation in weight gain in challenged animals was also influenced by nutrient ingestion, such as protein and methionine. The mycotoxin effect on growth was greater in male pigs (-19%) compared to females (-15%). Mortality rate and some hematological parameters were also influenced by mycotoxins in broilers. Relative weight of organs increased in challenged pigs (liver, kidneys and heart) and broilers (liver, kidneys, lungs and gizzard). Mycotoxins influence on performance, productive indexes and organ weight in pigs and broilers. However, the magnitude of the effects varies with the type and concentration of mycotoxin, sex and age of the animal, as well as nutritional factors.
Dois trabalhos foram desenvolvidos com o objetivo de estudar, através de meta-análise, a relação das micotoxinas com o desempenho e o peso de órgãos de suínos e frangos de corte. As bases de dados totalizaram 13.196 suínos (85 artigos publicados entre 1968 e 2010) e 37.371 frangos de corte (98 artigos, entre 1980 e 2009). A meta-análise foi realizada através de três análises sequenciais: estudos gráficos, de correlação e de variância-covariância. Suínos desafiados por micotoxinas apresentaram redução de 18% no consumo de ração e de 21% no ganho de peso. Frangos de corte desafiados apresentaram redução de 12% no consumo de ração e 14% no ganho de peso. As micotoxinas com maior impacto sobre o desempenho foram deoxinivalenol e aflatoxinas para os suínos, e ocratoxinas e aflatoxinas para as aves. A concentração de micotoxinas nas dietas e a idade dos animais ao desafio foram as variáveis que mais ajustaram o coeficiente de determinação nas equações para estimar o efeito das micotoxinas sobre o ganho de peso. O efeito das micotoxinas sobre o crescimento foi maior nos animais jovens. Além disso, a análise de resíduos mostrou que a maior parte da variação no ganho de peso foi explicada pela variação no consumo de ração (87% nos suínos e 65% nas aves). A variação no ganho de peso em animais desafiados também foi influenciada pela ingestão de nutrientes, como proteína e metionina. O efeito das micotoxinas sobre o ganho de peso foi maior nos suínos machos (-19%) que nas fêmeas (-15%). A taxa de mortalidade e alguns parâmetros hematológicos também foram influenciados pelas micotoxinas nos frangos de corte. O peso relativo dos órgãos aumentou nos suínos (fígado, rins e coração) e nas aves (fígado, rins, pulmões e moela) desafiadas. As micotoxinas influenciam o desempenho, os índices produtivos e o peso dos órgãos em suínos e frangos de corte. No entanto, a magnitude destes efeitos varia com o tipo e a concentração de micotoxinas, o sexo e a idade do animal, bem como com fatores nutricionais.
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Oliveira, Filho Jose Carlos de. « Intoxicação em búfalos (Bubalus bubalis) por Baccharis megapotamica var. weirii ». Universidade Federal de Santa Maria, 2012. http://repositorio.ufsm.br/handle/1/4063.
Texte intégralRésumé :
Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorIn the first part of the thesis, the spontaneous occurrence of an outbreak of Baccharis megapotamica var. weirii poisoning in buffalo in the Central region of the State of Rio Grande do Sul is reported. Ten out of 50 buffalo died 24 48 hr after being introduced into a pasture containing abundant amounts of the plant. Factors influencing the ingestion of the plant and consequent toxicosis included hunger, stress caused by shipment, and unfamiliarity with the plant. Clinical signs included serous ocular discharge, incoordination, mild bloat, and muscle trembling. One buffalo was necropsied. Gross findings included dehydration, abundant liquid in the rumen, reddening of the mucosa of forestomachs, abomasum, and intestine, and edema of the wall of the rumen. The main histologic lesions were superficial to full thickness degeneration and necrosis of the stratified epithelium lining the forestomachs, necrosis of the intestinal mucosa, and widespread lymphoid necrosis. A calf (Bos taurus) was fed a single dose of 5 g/kg/body weight of B. megapotamica var. weirii harvested from the same site where the buffalo died. Twenty hours after the administration of the plant this calf died with clinical signs and lesions similar to those observed in the naturally poisoned buffalo.sido consumida pelos búfalos. In the second part of the thesis, Five male 6-8 month-old Murrah buffalo calves were orally dosed with the fresh aerial parts of Baccharis megapotamica var. weirii at doses of 1, 3, 4, 5 and 10 g/kg body weight (bw) (~1-10 mg macrocyclic trichothecenes/kg/bw). The B. megapotamica used for the experiment was harvested on a farm where a recent spontaneous outbreak of poisoning caused by such plant had occurred. Clinical signs appeared 4-20 hours and 4 buffalo died 18-49 hours after the ingestion of the plant. Clinical signs were apathy, anorexia, and watery diarrhea, fever, colic, drooling, muscle tremors, restlessness, laborious breathing and ruminal atony, and dehydration. The most consistent gross findings were restricted to the gastrointestinal (GI) tract consisted of varying degrees of edema and reddening of the mucosa of the fore-stomachs. Histopathological findings consisted of varying degrees of necrosis of the epithelial lining of the fore-stomachs and of lymphocytes within lymphoid organs and aggregates. Fibrin thrombi were consistently found in sub-mucosal vessels of the fore stomachs and in the lumen of hepatic sinusoids. It is suggested that dehydration, septicemia and disseminated intravascular coagulation participate in the pathogenesis of the intoxication and play a role as a cause of death. A subsample of the B. megapotamica var. weirii was frozen-dried and ground and analyzed using UHPLC (Ultra High Performance Liquid Chromatography) with high resolution Time of Flight mass spectrometry and tandem mass spectrometry, it was shown that the plant material contained at least 51 different macrocyclic trichothecenes at a total level of 1.1-1.2 mg/g. About 15-20% of the total trichothecenes contents was found to be monosaccharide conjugates, with two thirds of these being glucose conjugates and one third constituted by six aldopentose conjugates (probably xylose), which has never been reported in the literature.
Na primeira parte dessa tese, relatamos a ocorrência natural de um surto de intoxicação por Baccharis megapotamica var. weirii em búfalos na Região Central do Rio Grande do Sul. Os animais haviam sido transportados de uma propriedade onde a planta não ocorria para uma propriedade infestada pela planta. Durante o transporte, os animais foram submetidos a um longo período de jejum e estresse. Como resultado, após o desembarque dos 50 búfalos transportados, dez morreram com doença de evolução aguda (24-48 horas). A maioria dos búfalos foi encontrada morta, mas os sinais clínicos observados em um búfalo incluíam lacrimejamento, incoordenação e fraqueza dos membros posteriores, desorientação, decúbito esternal, lateral e morte. Na necropsia de um animal foi observado acentuada desidratação, avermelhamento e edema da mucosa dos pré-estômagos e intestino. Na microscopia, as áreas vermelhas dos pré-estômagos e intestino correspondiam à necrose acentuada do epitélio. Em visita à propriedade foi observada grande quantidade de B. megapotamica (identificada posteriormente como B. megapotamica var. weirii) com sinais de ter sido consumida pelos búfalos. Na segunda parte da tese, reproduzimos experimentalmente a intoxicação por B. megapotamica var. weirii em búfalos para melhor caracterizar o quadro clínico-patológico da intoxicação na espécie, assim como determinar a dose tóxica e avançar no estudo da patogênese da intoxicação. Para tal, utilizamos cinco búfalos da raça Murrah com 6 a 8 meses de idade e peso variando entre 122 e 143 kg. Esses animais receberam em uma única administração por via oral, 1, 3, 4, 5 e 10 g/Kg das partes aéreas de Baccharis megapotamica var. weirii. A planta usada no experimento foi colhida na fazenda onde ocorreu o surto de intoxicação espontânea descrito acima. Os sinais clínicos apareceram 4-20 horas e quatro búfalos morreram 18-49 horas após a ingestão da planta. Os sinais clínicos consistiram de apatia, anorexia, diarreia aquosa, febre, cólica, salivação, tremores musculares, inquietação, respiração laboriosa, atonia ruminal e desidratação. Os achados macroscópicos mais consistentes estavam restritos ao trato gastrointestinal (GI) e consistiram de graus variados de edema e avermelhamento da mucosa dos pré-estômagos. Os achados histopatológicos consistiam de vários graus de necrose do epitélio de revestimento dos pré-estômagos e de linfócitos em agregados e órgãos linfoides. Trombos de fibrina foram consistentemente encontrados nos vasos da submucosa dos pré-estômagos e na luz dos sinusoides hepáticos. Uma subamostra de B. megapotamica var. weirii foi congelada a seco, moída e analisada usando UHPLC (Cromatografia Líquida de Ultra Alta Performance) com espectrometria de tempo-de-vôo de alta resolução e espectrometria de massa em tandem. Foi demonstrado que o material de planta analisado continha pelo menos 51 tricotecenos macrocíclicos diferentes num nível total de 1,1-1,2 mg/g. Cerca de 15-20% do conteúdo total de tricotecenos eram conjugados de monossacarídeos, sendo dois terços desses, conjugados de glicose e um terço constituídos por seis conjugados de aldopentose (provavelmente xilose). Em conclusão, o presente estudo descreveu pela primeira vez a intoxicação em búfalos por plantas do gênero Baccharis. A reprodução experimental demostrou que búfalos são um pouco mais resistentes a intoxicação por B. megapotamica var. weirii do que bovinos. Quanto à patogênese, foi sugerido que desidratação, septicemia e coagulação intravascular disseminada sejam fatores responsáveis pela morte dos animais afetados. Adicionalmente, foi descrito presença de tricotecenos constituídos por seis conjugados de aldopentose (provavelmente xilose) no B. megapotamica var. weirii, o que nunca tinha sido antes relatado na literatura.
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Mylona, Kalliopi. « Fusarium species in grains : dry matter losses, mycotoxin contamination and control strategies using ozone and chemical compounds ». Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7876.
Texte intégralRésumé :
This Project identified the relationships between storage conditions, dry matter losses (DMLs) caused by Fusarium species in cereal grains and mycotoxin contamination and assessed novel control strategies for post-harvest grain management including chemical control and ozone. F. graminearum, F. verticillioides and F. langsethiae were inoculated on wheat, maize and oats and stored under environmental conditions where marginal to optimum spoilage and mycotoxin contamination can occur. DMLs were calculated from the CO2 produced and were significantly correlated with deoxynivalenol (DON), zearalenone (ZEA), fumonisins (FUMs) and T-2 and HT-2 toxins respectively. Mycotoxin levels in wheat and maize exceeded the EU legislative limits with 0.9-1% DMLs. Therefore, CO2 monitoring during storage can indicate the level of contamination in a stored batch. Using CO2 production data at different water activity (aw) and temperature conditions, the environmental regimes at which F. langsethiae can grow and contaminate oats with T-2 and HT-2 toxins were identified for the first time. Five acids were examined in vitro and little effect was observed on Fusarium growth, in the aqueous form, while the effect on mycotoxin production varied. Dissolved in ethanol, adipic, fumaric and ferulic acids inhibited fungal growth and controlled DON and FUMs, but T-2 toxin was stimulated by the ethanol. Two garlic essential oils, propyl-propylthiosulfinate (PTS) and propyl propylthiosulfonate (PTSO) were studied for the first time. In vitro, 200 ppm reduced fungal growth (50-100%) and mycotoxin production by >90%. The efficacy was species-dependent. In naturally contaminated oats of 0.93 aw stored for 20 days, 16 ppm PTSO reduced T-2 and HT-2 toxins by 66% and ochratoxin A (OTA) by 88%, while 200 ppm PTS reduced OTA by 95%. In wheat, 100 ppm PTS reduced DON and ZEA and 300 ppm PTS reduced fumonisins by 40-80%. PTSO:PTS (1:1) at 400 and 600 ppm was very effective against DON and ZEA in wheat of 0.92 aw. Ozone (O3) exposure at 200 ppm for 30 min delayed Fusarium spore germination on media of 0.98 aw and inhibited germination at 0.94 aw. O3 was more effective against fungal spores than mycelium and little effect was observed on growing cultures. In vitro, mycotoxin production after exposure depended on the stage of life of the fungi. O3 reduced fungal populations in grains. Mycotoxin production in wet grains treated with 100-200 ppm O3 for 60 min and stored for up to 30 days was reduced or completely inhibited, depending on the species and the exposure system. Simultaneous drying of the grain due to the O3 passage was observed.
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Völkl, Andrea Ellen. « Transformation von Trichothecenen durch eine neue Bakterienart / ». 2000. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=009118639&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Wang, Jianfang. « Effect of T-2 toxin, a trichothecene mycotoxin, on the central nervous system in rats ». 1993. http://hdl.handle.net/1993/9715.
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Garvey, Graeme S. « Structural and functional studies of secondary metabolite acyltransferase superfamily members from the trichothecene mycotoxin biosynthetic pathway ». 2008. http://www.library.wisc.edu/databases/connect/dissertations.html.
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Schnerr, Helge [Verfasser]. « Quantitativer Nachweis von Deoxynivalenol und Trichothecene-bildenden Fusarium spp. mit Biosensor und PCR in Getreide / Helge Schnerr ». 2002. http://d-nb.info/965200639/34.
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Gottschalk, Christoph [Verfasser]. « LC-MS-, MS-Nachweismethoden für Typ A-, B- und D-Trichothecene und deren Anwendung in der Lebensmittel- und Umweltanalytik / Christoph Gottschalk ». 2009. http://d-nb.info/995971021/34.
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Perrin, Shannon Leigh. « The Production of Recombinant Trichothecene 3-O-Acetyl Transferase and Its Protective Effects on HD11 Chicken Macrophage Cells Challenged with T-2 Toxin ». 2008. http://trace.tennessee.edu/utk_gradthes/427.
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Koster, Brenda. « Evolutionary relationships among members of the fungal form-genus Stachybotrys, with emphasis on indoor-occurring taxa and the phylogenetic distribution and evolution of the trichothecene biosynthetic gene, tri5 ». 2006. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=449855&T=F.
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Park, Joung Joa. « Immunochemical study of trichothecenes ». 1995. http://catalog.hathitrust.org/api/volumes/oclc/32633665.html.
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Kim, No-soo. « Approaches to the synthesis of trichothecenes ». Thesis, 1992. http://hdl.handle.net/1957/37127.
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Alassane-Kpémbi, Imourana. « The intestinal toxicity of mycotoxins : Analysis of the interactions between type B trichothecenes ». Phd thesis, 2013. http://oatao.univ-toulouse.fr/17429/1/alassane_kpembi.pdf.
Texte intégralRésumé :
As for other food-born contaminants, the gastro-intestinal tract represents the first barrier against deoxynivalenol (DON). This mycotoxin frequently co-occurs with other type B trichothecenes (TCTs B) namely 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON), nivalenol (NIV) and fusarenon-X (FX). At the cellular level, DON binding to ribosomal RNA results in the inhibition of protein synthesis and triggers the mitogen-activated protein kinases (MAPKs) pathway that have been linked to immune response mechanisms. Thus, intestinal epithelial cell renewing is considered a putative target in DON toxicity. Moreover, based on the ability of DON to disturb the state of homeostasis of the inflammatory response in the intestine mimicking what is found in inflammatory bowel diseases (IBD), it is proposed that this mycotoxin may play a role in such diseases. However, very few is known about the intestinal toxicity of the other co-occuring TCT B, and their combined effects eventually. By means of in vitro human and porcine intestinal epithelial cells models and an ex vivo porcine jejunal explants model, we assessed the individual toxicity of five TCT B (DON, 3- and 15-ADON, NIV and FX) toward the intestine and we analyzed their combined toxicity in terms of additivity, synergy or antagonism. The tested TCT B significantly impaired the intestinal epithelial cell growth in the micromolar range, in increasing order of potency 3-ADON, DON, 15-ADON, NIV and FX. The toxicity of low doses of TCT B was synergistic. For mycotoxin concentrations corresponding to exposure levels reported for French and European consumers, the amplitude of this synergy ranged between 3 and 10. Benchmark dose analyses of the transcriptional data also showed that the exposure of the intestine to mycotoxin concentrations as low as 0.04µM for FX, 0.1µM for DON and 0.1µM for NIV could be associated to a significant activation of the inflammatory response mechanisms. Taken together, these results suggest that epithelial cell renewing and pro-inflammatory effects at the intestinal level may be consider very sensitive biomarkers for the assessment of the individual toxicity and interactions between the co-occurring TCTs B.