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Mabrok, Hoda Hussein Bakr. "Protective role of lignan-converting bacteria on chemically-induced breast cancer in gnotobiotic rats." Phd thesis, Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2013/6493/.
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Enterolignans (enterodiol and enterolactone) exhibit structural similarity to estradiol and have therefore been hypothesized to modulate hormone related cancers such as breast cancer. The bioactivation of the plant lignan secoisolariciresinol diglucoside (SDG) requires the transformation by intestinal bacteria including the deglycosylation of SDG to secoisolariciresinol (SECO) followed by demethylation and dehydroxylation of SECO to enterodiol (ED). Finally, ED is dehydrogenated to enterolactone (EL). It is unclear whether the bacterial activation of SDG to ED and EL is crucial for the cancer preventing effects of dietary lignans. The possible protective effect of bacterial lignan transformation on a 7,12 dimethylbenz(a)anthracene (DMBA)-induced breast cancer in gnotobiotic rats was investigated. Germ-free rats were associated with a defined lignan-converting consortium (Clostridium saccharogumia, Blautia producta, Eggerthella lenta, and Lactonifactor longoviformis). The rats colonized with lignan-converting bacteria consortium (LCC) were fed a lignan-rich flaxseed diet and breast cancer was chemical induced. Identically treated germ-free rats served as control. All bacteria of the consortium successfully colonized the intestine of the LCC rats. The plant lignan SDG was converted into the enterolignans ED and EL in the LCC rats but not in the germ-free rats. This transformation did not influence cancer incidence but significantly decreased tumor numbers per tumor-bearing rat, and tumor size. Cell proliferation was significantly inhibited and apoptosis was significantly induced in LCC rats. No differences between LCC and control rats were observed in the expression of the genes encoding the estrogen receptors (ERα and ERβ) and G-coupled protein receptor 30 (GPR30). Similar findings were observed for both insulin-like growth factor 1 (IGF-1) and epidermal growth factor receptor (EGFR) genes involved in tumor growth. Proteome analysis revealed that 24 proteins were differentially expressed in tumor tissue from LCC and germ-free. RanBP-type and C3HC4-type zinc finger-containing protein 1 (RBCK1) and poly(rC)-binding protein 1 (PBCP1) were down-regulated by 3.2- and 2.0-fold, respectively. These proteins are associated with cell proliferation. The activity of selected enzymes involved in the degradation of oxidants in plasma and liver was significantly increased in the LCC rats. However, plasma and liver concentrations of reduced glutathione (non-enzymatic antioxidant) and malondialdehyde (oxidative stress marker) did not differ between the groups. In conclusion, the bacterial conversion of plant lignan to enterolignans beneficially influences their anti-cancer effect. However, the mechanisms involved in these effects remain elusive.Enterolignanen (Enterodiol ED und Enterolacton EL) wird aufgrund ihrer strukturellen Ähnlichkeit zu Estradiol ein modulierender Einfluss auf hormonell bedingte Krebserkrankungen wie Brustkrebs nachgesagt. Das pflanzliche Lignan Secoisolariciresinoldiglucosid (SDG) wird durch Darmbakterien zum Enterolignan aktiviert. Dies erfolgt über dessen Deglykosylierung zu Secoisolariciresinol (SECO) gefolgt durch die Demethylierung und die Dehydroxylierung zu Enterodiol (ED). Schließlich wird ED zu Enterolacton (EL) dehydrogeniert. Es ist allerdings noch nicht bewiesen, dass die bakterielle Aktivierung von SDG zu ED und EL für die antikanzerogenen Wirkungen verantwortlich ist, die für dieses in der menschlichen Ernährung vorkommende Lignan beschrieben wurden. Um dies zu klären, wurde der Einfluss der bakteriellen Lignan-Transformation auf die Protektion gegenüber einem durch 7,12-Dimethylbenz(a)anthracen (DMBA)-induzierten Brustkrebs im gnotobiotischen Rattenmodell untersucht. Keimfreie Ratten wurden hierfür mit einem Konsortium aus vier Bakterienstämmen (Clostridium saccharogumia, Blautia producta, Eggerthella lenta, und Lactonifactor longoviformis) besiedelt, das die Umsetzung von SDG zu ED und EL katalysiert (LCC-Ratten). Ratten, die über den gesamten Versuchszeitraum keimfrei blieben, dienten als Kontrolle. Die Tiere wurden über 16 Wochen mit einer Leinsamen-Diät gefüttert, die reich an pflanzlichen Lignanen war. Während der Fütterung wurde bei allen Tieren Brustkrebs chemisch induziert. Das pflanzliche Lignan SDG wurde nur in den LCC Ratten zu den Enterolignanen ED und EL umgewandelt. Keimfreie Ratten zeigten keine Transformation von SDG. Die bakterielle Transformation von SDG hatte zwar keinen Einfluss auf die Inzidenz von Brustkrebs, jedoch verringerten sich durch die Besiedlung der Ratten mit SDG-transformierenden Bakterien die Anzahl von Tumoren pro tumortragender Ratte und die Tumorgröße deutlich. Zudem wurde die Zellproliferation in den LCC-Ratten deutlich gehemmt und die Apoptose induziert. Unterschiede in der Genexpression der Östrogenrezeptoren (ERα und ERß) und G-Protein-gekoppelte Rezeptoren (GPR30) wurden zwischen den LCC-Ratten und den Kontrolltieren nicht beobachtet. Ebenso verhielt es sich für die Gene des Insulinähnliche Wachstumsfaktoren 1 (IGF-1) und Epidermale Wachstumsfaktor rezeptoren (EGFR), welche in das Tumorwachstum involviert sind. Die Analyse des Proteoms des Tumorgewebes ergab 24 differentiell exprimierte Proteine zwischen keimfreien und LCC-Ratten. So wurden zum Beispiel die Proteine RanBP-type and C3HC4-type zinc finger-containing protein 1 (RBCK1) und poly(rC)-binding protein 1 (PBCP1), die mit der Zellproliferation assoziiert sind, in LCC-Ratten um das 3,2 bzw. 2,0-fache herunterreguliert. Die Aktivität ausgewählter antioxidativer Enzyme in Plasma und Leber war in den LCC-Ratten im Vergleich zu den keimfreien Tieren deutlich erhöht. Allerdings unterschieden sich die Konzentrationen von reduziertem Glutathion (nichtenzymatisches Antioxidans) und Malondialdehyd (oxidativer Stress-Marker) in Plasma und Leber nicht zwischen den beiden Besiedlungs-Gruppen. Zusammenfassend zeigen die Ergebnisse, dass die bakterielle Umwandlung von pflanzlichen Lignanen zu Enterolignanen deren antikanzerogene Wirkung entscheidend beeinflusst. Allerdings bleiben die zugrunde liegenden Mechanismen weiterhin ungeklärt.
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Okunishi, Tomoya. "Stereochemistry of Lignan Biosynthesis in Thymelaeaceae Plants." Kyoto University, 2003. http://hdl.handle.net/2433/149001.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第10276号
農博第1348号
新制||農||869(附属図書館)
学位論文||H15||N3797(農学部図書室)
UT51-2003-H697
京都大学大学院農学研究科応用生命科学専攻
(主査)教授 島田 幹夫, 教授 桑原 保正, 教授 坂田 完三
学位規則第4条第1項該当
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Dodson, A. P. J. "The use of lignin peroxidases to degrade lignin in plant cell walls." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46747.
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Lamp, Shane B. "Equipment specification, process control, and plant simulation for a lignin-fueled fluidized bed combustor plant." Morgantown, W. Va. : [West Virginia University Libraries], 1998. http://etd.wvu.edu/templates/showETD.cfm?recnum=224.
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Thesis (M.S.)--West Virginia University, 1998.Title from document title page. Document formatted into pages; contains xv, 98 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 84).
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Vassão, Daniel Giddings. "Biosynthesis of plant allyl/propenyl-phenols and 9,9'-deoxygenated lignans." Pullman, Wash. : Washington State University, 2008. http://www.dissertations.wsu.edu/Dissertations/Fall2008/d_vassao_120908.pdf.
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Lalaleo, Córdova Liliana Paulina. "New biotechnological systems for the research on aryltetralin lignans in Linum album." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/401647.
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Linum album is an herbaceous plant with medical interest due to its content of podophyllotoxin (PTOX), an aryltetralin lignan with cytotoxic activity. The study of biotechnological alternatives has generated big interest. Organ and cell in vitro cultures offer the possibility of suppling aryltetralin lignans in accordance with a sustainable and rational utilization of biodiversity, however they need to be improved. Thus, in this work we analyzed the lignan accumulation patterns in four biotechnological systems of L.album in order to find alternatives of bioproduction. The four biotechnological platforms were established with wild type and transformed cell suspension cultures, adventitious roots isolated from in vitro plants, and hairy roots. The predominant lignan produced by wild type and transformed cells was PTOX. The main lignan produced by adventitious and hairy roots was 6- MPTOX, adventitious roots showed to be more productive, and we can infer that the transformation did not change the lignan patterns. In addition, we have studied the response to the elicitor coronatine in these systems. Transformed cells were the most sensitive after elicitation and showed an arrest of biomass growth in relation to other systems. In general, the elicitation increased the lignan content, but the more elicited route in each system resulted to be the less productive. Transcript profiling changed in elicited conditions, specially for the PLR gene in transformed cells. The analysis of morphogenesis development in the production of podophyllotoxin derivatives in callus cultures of Linum album showed that, the absence of plant growth regulators are a predominant factor, to induce the organogenic
and the bioproduction as well. Finally, approaches aiming at increasing podophyllotoxin content require multiple enzymatic steps that facilitate the metabolic flow to the final products, most of them forming multiprotein complexes. Based on this, the Yeast two hibrid system allowed to identify CTB5 as a potential interactor of the PLR protein of Linum album, and evidences in other species indicate that CTB5 participates in the phenylpropanoid pathway.Linum album es una planta herbácea con interés farmacológico debido a su alto contenido de podofilotoxina (PTOX), el cual es un lignano de característica ariltetralin con actividad citotóxica. El estudio de las alternativas biotecnológicas ha generado gran interés. Los cultivos in vitro de órganos y células ofrecen la posibilidad de suministrar aryltetralin lignanos en acuerdo con una utilización sostenible y racional de la biodiversidad, sin embargo necesitan ser mejorados. Por tanto, en este trabajo se analizaron los patrones de acumulación de lignanos en cuatro sistemas biotecnológicos de L.album con el fin de encontrar alternativas en la bioproducción. Se establecieron cuatro plataformas biotecnológicas con cultivos en suspensión celular de tipo salvaje y transformados, raíces adventicias aisladas de plantas in vitro y raíces en cabellera. La PTOX fue el lignano predominante producido por células de tipo salvaje y transformadas. El principal lignano producido por las raíces adventicias y raíces transgénicas fue la metoxipodofilotoxina (MPTOX), en general las raíces adventicias fueron las más productivas, por lo cual podemos inferir que la transformación no afecto los patrones de bioproducción. Además, hemos estudiado la respuesta a la coronatina como elicitor en estos sistemas, donde las células transformadas fueron las más suceptibles a la elicitación mostrando una disminución en la biomasa en relación con los otros sistemas. En general, la elicitación aumentó el contenido de lignanos, aunque la ruta principal fue las menos favorecida en cada sistema. El perfil de expresión genética elicitadas, especialmente para el gen PLR en las células transformadas. El análisis del desarrollo de la morfogénesis en la producción de derivados de podofilotoxina en cultivos de callos del Linum álbum mostró que la ausencia de reguladores del crecimiento es un factor predominante para inducir la respuesta organogénica y la bioproducción. Finalmente, las aproximaciones que apuntan a aumentar el contenido de podofilotoxina requieren múltiples pasos enzimáticos que faciliten el flujo metabólico hacia los productos finales, la mayoría de ellos formando complejos multiproteicos. Basado en lo anterior, la técnica del doble hibrido en levadura nos permitió identificar la CTB5 como un potencial interactor de la proteína PLR del Linum álbum, hallada en otras especies como interactor en la ruta metabolica de los fenilpropanoides.
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Hoffman, Sister Angela. "Hormonal regulation of cell development and polyphenol biosynthesis in cultured Populus trichocarpa cells /." Full text open access at:, 1989. http://content.ohsu.edu/u?/etd,220.
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Muir, Shelagh R. "Ligand-gated calcium channels in higher plant membranes." Thesis, University of York, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319717.
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Lease, Kevin A. "Erecta and erecta-like mutants of Arabidopsis thaliana /." free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9974650.
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Uden, Wilhelmus van. "The production of podophyllotoxin and related cytotoxic lignans by plant cell cultures." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 1992. http://irs.ub.rug.nl/ppn/293040230.
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Radomski, Maria Izabel [UNESP]. "Teores foliares de silício, taninos e lignina, em Maytenus ilicifolia Martius ex Reiss. (espinheira-santa), em função de variáveis ambientais e genéticas." Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/103251.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
A espécie medicinal Maytenus ilicifolia, localiza-se naturalmente sob diferentes condições edafo-climáticas. Este fato implica em prováveis mecanismos de adaptação das populações naturais, cujas características químicas podem, ou não, estar fixadas geneticamente. A identificação da variabilidade fenotípica da espécie permite viabilizar práticas de manejo visando a produção de fitoterápicos com qualidade organoléptica, nutricional e terapêutica. Para identificar a influência do ambiente na composição fitoquímica de M. ilicifolia foram efetuados três estudos, o primeiro em quatro populações naturais distribuídas no Estado do Paraná, o segundo em um banco de germoplasma, e o terceiro em uma unidade de cultivo experimental onde foi conduzido um ensaio de fertilização baseado na aplicação de diferentes doses de um resíduo de siderurgia rico em Si. Foram avaliados os teores foliares de N, P, K, Ca, Mg, Fe, Mn, Cu, Zn, Si, Al, lignina, fenóis totais, fenóis não tanantes e taninos. Nas populações naturais também foi determinada a massa específica foliar. No banco de germoplasma, em função da elevada diversidade morfológica, foi efetuada a classificação dos indivíduos em morfotipos, tendo sido identificados nove morfotipos foliares, os quais apresentaram relação com alguns dos ambientes de origem das populações. Os estudos efetuados indicam que é possível efetuar o controle de compostos fenólicos presentes em M. ilicifolia, seja através do manejo de luz, interferindo tanto na síntese de lignina quanto dos taninos, seja por meio da aplicação de Si e Ca, regulando principalmente a síntese de fenóis totais e taninos.
Maytenus ilicifolia is a medicinal species that occurs naturally under different soils and light conditions. This fact involves adaptation mechanisms of the natural populations whose chemical characteristics can be or not genetically fixed. The identification of the genetic variability can viabilize the management practices to the production of phytotherapics with organoleptical, nutritional and therapeuthic quality. Three studies were developed to determine the influence of the environment in the phytochemical content of M. Ilicifolia and the samples were collected from four natural communities, a germoplasm bank, and an experimental area in wich there was fertilized with different doses a rich Si residue. There was determinate the specific leaf mass in leaves from the natural populations, also there was determinate the total content of N,P, K, Ca, Mg, Fe, Mn, Cu, Zn, Si, Al, lignin, total phenols and tannins in all samples. In the germoplasm bank the individual plants were classified in nine morphotypes, too. The studies indicate that is possible to controle the M. ilicifolia lignin and tannin composition by light management, as well as the total phenols and tannin by Si and Ca fertilization.
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Costa, Thales Henrique de Freitas. "Avaliação da recalcitrância de diferentes regiões oriundas de entrenós de cana-de-açúcar em híbridos com teores variados de lignina." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/97/97131/tde-28082013-094005/.
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O presente trabalho avaliou a recalcitrância de diferentes regiões do entrenó de plantas de cana-de-açúcar que apresentavam teores contrastantes de lignina total. As amostras com baixo teor de lignina corresponderam aos híbridos experimentais denominados de H58 e H89, com 18,6% e 16,8% de lignina, respectivamente. As amostras com elevado teor de lignina corresponderam ao híbrido H140 e a um cultivar comercial (CR), com 21,5% e 24,5% de lignina, respectivamente. De cada cana foram obtidas quatro regiões distintas dos entrenós: medula, interface medula-córtex, córtex e fração externa (epiderme mais córtex periférico). Cada uma das amostras foi submetida à hidrólise enzimática com celulases comerciais. Os resultados mostraram uma maior conversão de celulose e hemicelulose na região da medula (celulose: 86%, 78%, 85% e 50%; xilanas: 50%, 36%, 31% e 30% após 72h, para CR, H58, H89 e H140, respectivamente). O córtex e a fração externa foram as regiões mais recalcitrantes, já que as conversões de celulose e xilanas atingiu somente 10% a 38% no córtex e 6% a 10% na fração externa. Embora seja pouco recalcitrante, a medula representou menos do que 10% do volume e da massa do entrenó. Em contraste, o córtex representou 49% do volume do entrenó e 48% a 63% da massa, dependendo do híbrido estudado. A região medular também mostrou a predominância de glucanas (41% - 55%) e menor teor de hemiceluloses (16,8% - 20,5%; exceto H140) e lignina total (12,6% - 18,5%) em relação às demais frações. A determinação de ácidos hidroxicinâmicos nas amostras indicou a predominância de ligações destes ácidos na forma de éster com a hemicelulose e simultaneamente éter com a lignina, independentemente da fração de cana avaliada. Dentre os híbridos, o H89 e o H140 se destacaram por sua baixa e alta recalcitrância, respectivamente. Nas análises microscópicas, o número de feixes vasculares por área foi maior na região do córtex (13 a 22 feixes por 16 mm2) quando comparada com outras regiões, enquanto a fração externa apresentou apenas fibras. A medula se mostrou preenchida, em sua maior parte, por células do parênquima, contendo menos feixes vasculares (5 a 8 feixes por 16 mm2). Dentre os híbridos, o H140 foi o que apresentou menos feixes por área, porém com os maiores diâmetros (entre 390 e 583 ?m, dependendo da região). A presença de feixes vasculares mostrou ser muito importante para explicar a recalcitrância das amostras. Dentre os estudos de correlação realizados, foi possível notar que a recalcitrância das canas estudadas pode ser relacionada não apenas com o teor de lignina total, mas também com a densidade do material, a disponibilidade de celulose e a extensão dos feixes vasculares por área.This study evaluated the recalcitrance of different regions of the internodes of sugarcane plants which presented contrasting lignin contents. Samples with low lignin content corresponded to the experimental hybrids termed H58 and H89, each one with 18,6% and 16,8% of lignin, respectively. The samples with high lignin content corresponded to the hybrid H140 and a commercial variety of sugarcane (CR), with 21,5% and 24,5%, respectively. Different fractions of the internodes were obtained from each plant: pith, pith-rind interface, rind and outermost rind (epidermis plus peripheral rind). Each sample was submitted to enzymatic hydrolysis with commercial cellulases. Results showed a higher conversion of cellulose and hemicellulose in the pith (cellulose: 86%, 78%, 85% and 50%, xylan: 50%, 36%, 31% and 30% after 72 hours for CR, H58, H89 and H140, respectively). Rind and outermost rind were the most recalcitrant regions, since the cellulose and xylan conversions reached only 10% to 38% in rind and 6% to 10% in the outermost rind. Despite its low recalcitrance, the pith region represented less than 10% of the volume and the dry mass of the internode. In contrast, the rind represented 49% of the internode volume and 48% to 63% of the dry mass, depending on the evaluated hybrid. The pith region also showed the predominance of glucan (41% - 55%) and the lowest contents of hemicellulose (16.8% - 20.5%, except for H140) and total lignin (12.6% - 18.5%). From the hydroxycinnamic acids determination, it was found that these acids were mostly linked to hemicellulose as esters and, simultaneously, to lignin as ether, regardless which fraction was analyzed. Among the hybrids, H89 and H140 stood out for its low and high recalcitrance, respectively. In microscopic analysis, the number of vascular bundles per area was greater in the rind region (13 to 22 bundles per 16 mm2) when compared to other regions, meanwhile the outermost rind showed only fiber cells. The pith showed itself occupied mostly by parenchyma cells, containing less vascular bundles (5 to 8 bundles per 16 mm2). Among the hybrids, H140 showed the smallest number of vascular bundles per area, but with the largest diameters (between 390 and 583 ?m, depending on the region type). The presence of the vascular bundles was found to be very important in order to explain the recalcitrance of the samples. Among the correlation analysis performed, it was noticeable that the recalcitrance of the studied sugarcanes could be related, not only to the total lignin content, but also to the biomass density, the cellulose availability and the extent of vascular bundles per area.
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Hepworth, David G. "The mechanical properties of tobacco plants with genetically modified lignin." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339456.
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Dickinson, George David. "Ligand-gated calcium mobilisation in higher plants." Thesis, University of York, 2002. http://etheses.whiterose.ac.uk/10822/.
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Coletta, Luciana Della. "Decomposição foliar na Floresta Ombrófila Densa em diferentes altitudes e condições climáticas." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/64/64135/tde-06102015-115523/.
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A decomposição da serapilheira é um processo fundamental, que influencia o armazenamento de carbono (C) no solo e a disponibilidade de nutrientes para as plantas e os microrganismos, afetando assim a distribuição de espécies em um ecossistema. A Floresta Ombrófila Densa, conhecida popularmente como Mata Atlântica localiza-se ao longo da costa brasileira e é caracterizada pela elevada diversidade e endemismo. Dentre as diversas famílias botânicas presentes neste ecossistema, a família Fabaceae apresenta grande importância, tanto pela sua abundância e ampla distribuição, como por desempenhar um papel importante no ciclo do nitrogênio (N) terrestre. O objetivo deste estudo foi investigar as taxas de decomposição e mudanças na composição inorgânica e orgânica da serapilheira ao longo desse processo em duas fisionomias de florestas (Terras Baixas vs. Montana) localizadas em diferentes altitudes (100 m vs. 1000 m). Levantamentos realizados em diferentes formações vegetais da Floresta Ombrófila Densa ao longo de um gradiente altitudinal indicam diferenças significativas na disponibilidade de N nos solos em diferentes altitudes, além de diferenças contrastantes na temperatura do ar. Essas diferenças podem influenciar na composição das folhas, que por sua vez interfere no processo de decomposição. Os experimentos com litter bags foram instalados no início do período seco e outro no início do período chuvoso, com duração de um ano cada um. As espécies selecionadas para esse estudo pertencem a família Fabaceae (Inga lanceifolia e Swartzia simplex var. grandiflora), e foram comparadas a uma espécie pertencente a família Monimiaceae (Molinedia schottiana). A taxa de decomposição e a degradação da lignina, celulose, hemicelulose e do nitrogênio foram mais rápidos na leguminosa da floresta de Terras Baixas em comparação a não-leguminosa. Por outro lado, não houve diferença nas taxas de decomposição entre I. lanceifolia e M. schottiana da floresta Montana. Mas, comparando a espécie M. schottiana, a não-leguminosa comum nas duas altitudes, esta espécie se decompôs mais rapidamente na floresta de Terras Baixas em relação a Montana. Na floresta de Terras Baixas, não só as temperaturas mais elevadas, mas também as diferentes característica químicas, como o elevado teor de N e a baixa razão C:N na serapilheira da leguminosa podem acelerar os processos de decomposição nesta floresta, além disso, a menor concentração de polifenóis na M. schottiana a 100 m comparada a 1000 m de altitude também pode ter favorecido as elevadas taxas de decomposição na floresta de Terras Baixas. Portanto, as características químicas da serapilheira também parecem regular as taxas de decomposiçãoLitter decomposition is a fundamental process that affects carbon (C) storage in the soil and nutrients availability for plants and microorganisms, impacting the distribution of species in a given ecosystem. The Dense Ombrophilous Forest, commonly known as Atlantic Forest, is located along the Brazilian coast and characterized by its high diversity and endemism. Among many botanic families existing in this ecosystem, the Fabaceae family has great importance because it is very abundant and well distributed and also plays an important role in the terrestrial nitrogen (N) cycle. The objective of this study was to investigate decomposition rates and changes in inorganic and organic litter composition throughout this process in two forest physiognomies (Lowland vs. Montane) located in different altitudes (100 m vs. 1000 m). Studies realized along an altitudinal gradient in different vegetation formations of Dense Ombrophilous Forest indicate significant differences in N availability in the soil of different altitudes, and contrasting differences in air temperature. These differences can influence leaf decomposition, which interferes in the decomposition process. One of the experiments with litter bags were set at the beginning of the dry season and another at the beginning of the wet season, each one with duration of one year. The species selected for this study belong to the Fabaceae family (Inga lanceifolia and Swartzia simplex var. grandiflora) and were compared to another species of the Monimiaceae family (Molinedia schottiana). The decomposition rates, lignin, cellulose, hemicellulose and nitrogen degradation were faster in legume than non-legume in Lowland forest. On the other hand, there was no difference in decomposition rates between M. schottiana and I. lanceifolia in Montane forest. But, comparing M. schottiana specie, a common non-legume in the two altitudes, this specie decomposed faster in Lowland than Montane forest. In Lowland forest, not only higher temperatures, but also the different chemical characteristics, such as high nitrogen content and low C:N ratio in the legume litter could accelerate the decomposition processes in this forest, in addition, lower polyphenols concentration in M. schottiana in Lowland compared to Montane forest can also favored the high decay rates in Lowland forest. Therefore, the litter chemical characteristics also appear to regulate the decomposition rates
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Goh, Kar Mun. "Induction of defence response in lignin biosynthesis of Elaeis guineensis during an interaction with Ganoderma boninense." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33466/.
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Oil palm is a dynamic economic crop that provides good income and is a source of dietary energy for the global population by palm oil. However, oil palm has low resistance to basal stem rot (BSR) disease caused by Ganoderma boninense. It is hypothesised that the process of cell wall lignification could serve as the first line of defence in oil palm. Lignification delays the infection progress of G. boninense. This present study evaluated the underlying molecular and biochemical lignin biosynthesis events and the quantification and deposition patterns of lignin in oil palm upon G. boninense infection. In this study, an artificial in planta infection system was used to inoculate one month-old oil palm plantlets with G. boninense (GBLS strain) at three levels of treatments (control, T1; wounded, T2 and infected, T3). Post-infection analyses were conducted at 2 day intervals for a period of 8 days. The analyses included the disease severity index (DSI) and physical properties of the plantlets (height, weight, stem diameter, root length and leaf chlorophyll content), the degree of G. boninense colonisation on plantlets stem tissues, total phenolic content and total amount of G. boninense DNA in planta. The results showed a significant (P < 0.001) reduction in the leaf chlorophyll content (from 32.59 to 12.61 SPAD) and severe deterioration of the internal stem tissues. Escalation of DSI values (from 5.56 to 70.37%), total phenolic contents (from 1.78 to 3.07 mg g-1) and the quantity of G. boninense DNA (from 4.04 to 757.15 mg g-1) in the infected (T3) plantlets on 8 day post-inoculation (DPI) were observed. These differences (P > 0.05) were absent in control (T1) and wounded (T2) plantlets. Colorimetric enzyme assays and quantitative PCR amplifications (qPCR) were carried out to assess the enzyme activities and relative gene expressions of intermediate enzymes (phenylalanine ammonia lyase, PAL; cinnamate 4-hydroxylase, C4H; caffeic acid O-methyltransferase, COMT; cinnamyl alcohol dehydrogenase, CAD) for lignin biosynthesis in oil palm plantlets. Enzyme activities of PAL, C4H and COMT were generally induced in infected plantlets, except for CAD which was reduced in all plantlets throughout the experiment. Meanwhile, relative expression of EgPAL, EgCOMT and EgCAD were up-regulated in infected plantlets by 3 to 6 fold at 2 to 4 DPI as compared to the control plantlets, except for EgC4H which was initially down-regulated, but was induced later at 8 DPI with the highest change recorded of 13.22. A biphasic transient induction pattern of lignin biosynthesis genes was observed in oil palm plantlets upon infection by G. boninense. The lignothioglycolic acid (LTGA) assay, histochemical staining with toluidine blue-O (TBO), Maúle reagent and phloroglucinol-HCl and gas chromatography (GC) equipped with a flame ionisation detector (FID) were used to estimate and detect the total lignin content, lignin deposition patterns and the composition of lignin derivatives such as syringaldehyde and vanillin, respectively. Results showed the infected plantlets scored the highest level of total lignin content at 93.63 TGA g-1 derivatives at 8 DPI. Lignin was mainly deposited on the collenchyma and cuticle layers, as observed via staining with TBO and Maúle reagents, but red colouration from phloroglucinol-HCl, which stained for guaiacyl-lignin was absent in all specimens. Total amounts of syringaldehyde and vanillin increased in infected plantlets at 6 DPI, with higher increment of vanillin (353%) than syringaldehyde (59%) content. From this study, an early induction of lignification in oil palm was confirmed in response to the infection of G. boninense. This resulted in the accumulation and deposition of lignin compounds in the cell walls of oil palm. An increase in lignin content of oil palm was believed to have enhanced its tolerance towards G. boninense infection and delayed the progression of BSR disease, which could be a temporary solution to the BSR problem in oil palm. Further research for an effective cure or prevention is required.
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Ku, Chuen Fai. "Arylnaphthalene lignans from justicia plants as potent broad-spectrum antiviral agents." HKBU Institutional Repository, 2020. https://repository.hkbu.edu.hk/etd_oa/836.
Full textAbstract:
Background: The emergence of viral diseases has been the major threat to public health and social stability. A hundred years ago, 1918 Spanish flu (H1N1) pandemic spread worldwide, and about 3% ~ 5% of the world's population died from the flu-related illnesses. It is known as the deadliest catastrophic pandemics in human history. There have been five Public Health Emergency of International Concern (PHEIC) declarations over the past decade, including the 2014 Ebola outbreak in west Africa, the 2016 Zika outbreak and the ongoing COVID-19 pandemic. There is always a new strain of virus emerging on the horizon. We have urgent need to develop more broad-spectrum antivirals, which work effective against multiple viruses, for thwarting outbreaks in the future. Objective: Based on our previous experience in search of anti-HIV compounds from topical plants, we aimed to discover novel antiviral lead compounds from Justicia plants collected in Hong Kong. Further, structure modification of the natural compounds can lead to optimization of their drug properties for further development as drug candidates. To determine the antiviral targets of the lead compounds will further provide insights to elucidate the mechanism of actions. The present studies are to discover the antiviral lead compounds from Justicia plants, to analyze the structure-activity relationship of the modified structures, to identify the molecular targets of the lead compounds as antiviral agents against the multiple viruses. Methodology: Four common Justicia plants were collected in Hong Kong. The plant extracts and compounds isolated from the plants were explored for their antiviral activities via our established "One-Stone-Two-Birds" antiviral assay. Time-of-addition experiments were performed to determine the target stages of the antiviral compounds on the viral replication. Computational techniques (3D-QSAR and in silico pharmacokinetics evaluation) were employed to elucidate the structure-activity relationship of the compounds and thereby optimize their structures to enhance the antiviral activity. Comprehensive activity-based protein profiling (ABPP) of biotin-linked compounds using SWATH-MS technique was performed to identify the protein target(s) of the lead compounds in an unbiased manner. The role of the molecular target in viral replication was further verified by mRNA knockdown using siRNA. Result: The extracts of Justicia procumbens and Justicia championii showed potent antiviral effects with low cytotoxicity among the collected Justicia plants. By correlating the antiviral activity with their HPLC-UV profiles, arylnaphthalene lignans (ANLs) were determined as the principle active components. Among the isolated compounds from J. procumbens, diphyllin exhibited strong antiviral activities against VSV/HIV, H5N1/HIV and EBOV/HIV pseudoviruses with EC50 values ranging from 30-100nM. In time-of-addition experiments, diphyllin mainly acts on the entry stage of the viral infection. Considering the broad-spectrum antiviral properties and antiviral mechanism together, diphyllin is probably a host-targeting antiviral agent. In a subsequent lead optimization, a reliable and predictive 3D-QSAR was established from 25 synthesized ANLs. Compound 31 was found as the most potent antiviral agent based on the 3D-QSAR model. It showed 70 times more potent antiviral activity than the parent diphyllin, with retained broad-spectrum antiviral properties and improved predicted ADMET properties. In addition, comprehensive ABPP analysis of the biotin-linked diphyllin was employed for the target identification of the ANL compounds. Total 2343 proteins were captured by the ABPP probes. By quantitative analysis, the protein TFAM showed significant affinity to the diphyllin-based ABPP probes. The viral susceptibility of TFAM-deficient cells was shown to be reduced in the subsequent validation. We thus determined TFAM as the potential antiviral drug target of the ANL compounds against a broad spectrum of viruses.
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Wadenbäck, Johan. "Lignin studies of transgenic Norway spruce /." Uppsala : Dept. of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/200664.pdf.
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Broomhead, A. J. "Chemical and biochemical studies of tumour inhibitory aryl tetralin lignans." Thesis, University of Nottingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235376.
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Kiyoto, Shingo. "Immunolocalization of 8-5′ and 8-8′ linked structure of lignin in plant cell walls." Kyoto University, 2015. http://hdl.handle.net/2433/202813.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第19379号
農博第2149号
新制||農||1037(附属図書館)
学位論文||H28||N4959(農学部図書室)
32393
新制||農||1037
京都大学大学院農学研究科森林科学専攻
(主査)教授 髙部 圭司, 教授 髙野 俊幸, 教授 杉山 淳司
学位規則第4条第1項該当
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Eberhardt, Thomas Leonard. "Characterization of lignin deposition in Pinus taeda L. cell suspension cultures." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-07282008-134210/.
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Denny, Carina. "Atividade anticancer de extratos e principios ativos obtidos de Virola sebifera (Myristicaceae)." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289321.
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Orientadores: João Ernesto de Carvalho, Mary Ann FoglioTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-06T02:42:02Z (GMT). No. of bitstreams: 1 Denny_Carina_D.pdf: 2044243 bytes, checksum: 37d9912d0a46cbfff8c47cde834817fd (MD5) Previous issue date: 2006
Resumo: Modelos de avaliação da citotoxicidade têm proporcionado a obtenção de importantes dados preliminares, ajudando a selecionar extratos de plantas com propriedade antitumoral para estudos futuros. Como parte de um programa de screening de plantas medicinais brasileiras e produtos naturais com propriedades anticâncer, o presente trabalho apresenta a atividade da Virola sebifera (Myristicaceae), uma árvore endêmica do Cerrado brasileiro. O objetivo geral desse trabalho foi avaliar as propriedades in vitro e in vivo de amostras da V. sebifera. além de isolar e identificar seus compostos ativos. O primeiro estudo descreve a atividade antiproliferativa em cultura de células tumorais humanas de duas lignanas e dois policetídeos isolados das folhas da V. sebifera. Assim, reportamos o isolamento e elucidação estrutural de um novo policetídeo 3,5-diidro-2-(l'-oxo-3'-hexadecenil)-2-ciclohexano-l-ona com alta atividade antiproliferativa contra 8 linhagens de células tumorais humanas. No segundo estudo, purificamos a fração ativa (FR4) a partir do extrato bruto diclorometânico, com atividade in vitro (IC50- 5,19-10,57 (xg/mL - ensaio do SRB) pãrã âs mesmas linhagens celulares. Pãrã ãvãliãr ã atividade in vivo da fração ativa utilizamos o ensaio da hollow fiber. Assim, foram estabelecidas as condições de crescimento para as linhagens celulares MCF-7, NCI-ADR e OVCAR03 em fibras (hollow fibers) implantadas no abdômen (i.p.) e no dorso (s.c.) de camundongos imunocompetentes. Os animais foram tratados com FR4 (500mg/kg), doxorubicina (6mg/kg) ou veículo intraperitonealmente. Após 14 dias de tratamento, as fibras foram retiradas, seguindo-se a coloração do MTT para determinação da densidade de células viáveis. A fração FR4 demonstrou efeito significante contra células de mama (MCF-7) e ovário (OVCAR03). A confirmação das propriedades anticâncer in vitro e in vivo da Virola sebifera apresentadas nesse estudo, nos permite avançar em pesquisas futuras, orientando a seleção de outros modelos e estudos de mecanismo de ação
Abstract: Cytotoxicity screening models provide important preliminary data to help select plant extracts with potential antitumor properties for future work. As part of a screen program searching for Brazilian medicinal plants and natural products with anticancer properties, the present investigation reports the anticancer activity the Virola sebifera (Myristicaceae), an endemic tree from the Brazilian Cerrado. The overall aim of this work was the evaluation of in vitro and in vivo properties of samples from V. sebifera, there for the isolation and identification of the active compounds. The first study describes the antiproliferative properties against human cell lines of two lignans and two polyketides isolated from leaves of V. sebifera. Herein we report the isolation and structure elucidation of a novel polyketide 3,5-dihydro-2-(r-oxo-3J-hexadecenyl)-2-cyclohexen-l-one with high antiproliferative activity against 8 human cancer cell lines. In the second study, we purified the active fraction (FR4) from the crude dichloromethanic extract with in vitro activity (IC5ri=5.19 - 10.57 pg/mL - SRB assay) against the same cell lines. In addition, the hollow fiber assay was used to study the effect in vivo of the active fraction (FR4). Using this model, we have established growth conditions for MCF-7, NCI-ADR and OVCAR03 cells implanted at the intraperitoneal (i.p.) and subcutaneous (s.c.) compartments of immunocompetent mice. Then, the animals were treated with FR4 (500 mg/kg). doxorubicin (6mg/kg) or vehicle only intraperitoneally. After 14 days the fibers were retrieved, followed by determination of living cell density by MTT staining. FR4 showed significant effect against breast (MCF-7) and ovarian (OVCAR03) tumor cells. The anticancer properties of Virola sebifera in vitro and in vivo was confirmed in this study. These findings may guide future studies in other models and detailed studies on the mechanisms of action
Doutorado
Farmacologia, Anestesiologia e Terapeutica
Doutor em Odontologia
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Radomski, Maria Izabel 1966. "Teores foliares de silício, taninos e lignina, em Maytenus ilicifolia Martius ex Reiss. (espinheira-santa), em função de variáveis ambientais e genéticas /." Botucatu : [s.n.], 2006. http://hdl.handle.net/11449/103251.
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Orientador: Leonardo Theodoro BüllBanca: Lin Chau Ming
Banca: Carmem Silvia F. Boaro
Banca: Antonio Francisco J. Bellote
Banca: Hellton Damin da Silva
Resumo: A espécie medicinal Maytenus ilicifolia, localiza-se naturalmente sob diferentes condições edafo-climáticas. Este fato implica em prováveis mecanismos de adaptação das populações naturais, cujas características químicas podem, ou não, estar fixadas geneticamente. A identificação da variabilidade fenotípica da espécie permite viabilizar práticas de manejo visando a produção de fitoterápicos com qualidade organoléptica, nutricional e terapêutica. Para identificar a influência do ambiente na composição fitoquímica de M. ilicifolia foram efetuados três estudos, o primeiro em quatro populações naturais distribuídas no Estado do Paraná, o segundo em um banco de germoplasma, e o terceiro em uma unidade de cultivo experimental onde foi conduzido um ensaio de fertilização baseado na aplicação de diferentes doses de um resíduo de siderurgia rico em Si. Foram avaliados os teores foliares de N, P, K, Ca, Mg, Fe, Mn, Cu, Zn, Si, Al, lignina, fenóis totais, fenóis não tanantes e taninos. Nas populações naturais também foi determinada a massa específica foliar. No banco de germoplasma, em função da elevada diversidade morfológica, foi efetuada a classificação dos indivíduos em morfotipos, tendo sido identificados nove morfotipos foliares, os quais apresentaram relação com alguns dos ambientes de origem das populações. Os estudos efetuados indicam que é possível efetuar o controle de compostos fenólicos presentes em M. ilicifolia, seja através do manejo de luz, interferindo tanto na síntese de lignina quanto dos taninos, seja por meio da aplicação de Si e Ca, regulando principalmente a síntese de fenóis totais e taninos.
Abstract: Maytenus ilicifolia is a medicinal species that occurs naturally under different soils and light conditions. This fact involves adaptation mechanisms of the natural populations whose chemical characteristics can be or not genetically fixed. The identification of the genetic variability can viabilize the management practices to the production of phytotherapics with organoleptical, nutritional and therapeuthic quality. Three studies were developed to determine the influence of the environment in the phytochemical content of M. Ilicifolia and the samples were collected from four natural communities, a germoplasm bank, and an experimental area in wich there was fertilized with different doses a rich Si residue. There was determinate the specific leaf mass in leaves from the natural populations, also there was determinate the total content of N,P, K, Ca, Mg, Fe, Mn, Cu, Zn, Si, Al, lignin, total phenols and tannins in all samples. In the germoplasm bank the individual plants were classified in nine morphotypes, too. The studies indicate that is possible to controle the M. ilicifolia lignin and tannin composition by light management, as well as the total phenols and tannin by Si and Ca fertilization.
Doutor
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Jordan, Nicholas David. "Partial purification and characterisation of a wheat N-acetyl-#beta#-D-hexosaminidase and its role in defensive lignin deposition." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240956.
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Ku, Chuen Fai. "Arylnapthalene liguans from justicia plants as potent broad-spectrum antiviral agents." HKBU Institutional Repository, 2020. https://repository.hkbu.edu.hk/etd_oa/779.
Full textAbstract:
Background: The emergence of viral diseases has been the major threat to public health and social stability. A hundred years ago, 1918 Spanish flu (H1N1) pandemic spread worldwide, and about 3% ~ 5% of the world's population died from the flu-related illnesses. It is known as the deadliest catastrophic pandemics in human history. There have been five Public Health Emergency of International Concern (PHEIC) declarations over the past decade, including the 2014 Ebola outbreak in west Africa, the 2016 Zika outbreak and the ongoing COVID-19 pandemic. There is always a new strain of virus emerging on the horizon. We have urgent need to develop more broad-spectrum antivirals, which work effective against multiple viruses, for thwarting outbreaks in the future. Objective: Based on our previous experience in search of anti-HIV compounds from topical plants, we aimed to discover novel antiviral lead compounds from Justicia plants collected in Hong Kong. Further, structure modification of the natural compounds can lead to optimization of their drug properties for further development as drug candidates. To determine the antiviral targets of the lead compounds will further provide insights to elucidate the mechanism of actions. The present studies are to discover the antiviral lead compounds from Justicia plants, to analyze the structure-activity relationship of the modified structures, to identify the molecular targets of the lead compounds as antiviral agents against the multiple viruses. Methodology: Four common Justicia plants were collected in Hong Kong. The plant extracts and compounds isolated from the plants were explored for their antiviral activities via our established "One-Stone-Two-Birds" antiviral assay. Time-of-addition experiments were performed to determine the target stages of the antiviral compounds on the viral replication. Computational techniques (3D-QSAR and in silico pharmacokinetics evaluation) were employed to elucidate the structure-activity relationship of the compounds and thereby optimize their structures to enhance the antiviral activity. Comprehensive activity-based protein profiling (ABPP) of biotin-linked compounds using SWATH-MS technique was performed to identify the protein target(s) of the lead compounds in an unbiased manner. The role of the molecular target in viral replication was further verified by mRNA knockdown using siRNA. Result: The extracts of Justicia procumbens and Justicia championii showed potent antiviral effects with low cytotoxicity among the collected Justicia plants. By correlating the antiviral activity with their HPLC-UV profiles, arylnaphthalene lignans (ANLs) were determined as the principle active components. Among the isolated compounds from J. procumbens, diphyllin exhibited strong antiviral activities against VSV/HIV, H5N1/HIV and EBOV/HIV pseudoviruses with EC50 values ranging from 30-100nM. In time-of-addition experiments, diphyllin mainly acts on the entry stage of the viral infection. Considering the broad-spectrum antiviral properties and antiviral mechanism together, diphyllin is probably a host-targeting antiviral agent. In a subsequent lead optimization, a reliable and predictive 3D-QSAR was established from 25 synthesized ANLs. Compound 31 was found as the most potent antiviral agent based on the 3D-QSAR model. It showed 70 times more potent antiviral activity than the parent diphyllin, with retained broad-spectrum antiviral properties and improved predicted ADMET properties. In addition, comprehensive ABPP analysis of the biotin-linked diphyllin was employed for the target identification of the ANL compounds. Total 2343 proteins were captured by the ABPP probes. By quantitative analysis, the protein TFAM showed significant affinity to the diphyllin-based ABPP probes. The viral susceptibility of TFAM-deficient cells was shown to be reduced in the subsequent validation. We thus determined TFAM as the potential antiviral drug target of the ANL compounds against a broad spectrum of viruses.
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Ayella, Allan K. "Wheat lignans and cancer prevention." Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/335.
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Algar, Natalie. "Stretched to the limit : leaf tensile properties and lignin content of resurrection plants." Bachelor's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/24939.
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Leaf tensile strength was measured for four resurrection plants, Craterostigma wilmsii Engl, Xerophyta schlecteri (Baker) N.L. Menezes, Xerophyta humilis (Baker) T. Durand & Schinz and Sporobolus stapfianus Gandoger, as well as two desiccation-sensitive controls, Zea mays L. and Arabidopsis thaliana (L.) Heynh. (ecotype Columbia) at full hydration and after dehydration, both on the plant (naturally-dried) and rapidly off the plant causing death (flash-dried). In the desiccation-tolerant plants, leaf tensile strength was higher in the monocots than the dicots at full hydration. Three different mechanisms of cell protection occur in resurrection plants on drying: cell-wall folding, packing vacuoles with non-aqueous solute or a combination of the two. Tensile strength in C. wilmsii ( dicot) increased when naturally-dried but decreased when flash-dried, possibly due to the nature of the drying mechanisms (wall folding). The, leaf tensile strength of the Xerophyte species, both monocots, increased when naturally dried and when flashdried. Xerophyte species pack their vacuoles during desiccation. S. stapfianus, a grass which uses a combination of wall folding and vacuole packing, had the highest tensile strength possibly due to its unique architectural structure. Differences in leaf architecture, in terms of lignin content, were examined using light microscopy after histo-chemical staining for lignin, which showed that monocotyledons had a higher percentage of lignin per unit leaf cross-sectional area than dicotyledons. A regression analysis revealed that leaf tensile strength and lignin content were positively correlated in fully hydrated leaves I but no relationship existed between lignin content and naturally dried leaves. This may be due to variations of protective mechanisms induced during desiccation by the four resurrection plants. Notching was observed in X schlechteri, behaving differently to grasses which are notch-insensitive, possibly due to large lignin contents on the outer edges of the leaves.
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寶詠恩 and Vivienne Valerie Claire Bucher. "Distribution of lignin-modifying enzymes among aquatic fungi and theirability to degrade lignocellulose substrates." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31243988.
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Li, Wanfei. "Chemical synthesis of anti-HIV compounds based on the aryl naphthalene lignans identified from justicia plants." HKBU Institutional Repository, 2019. https://repository.hkbu.edu.hk/etd_oa/685.
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Background: Natural products have been a rich source for the discovery of lead compounds in modern drug discovery. 6,7'-Cyclolignans are a class of secondary metabolites which are widely distributed in more than 20 families. This important class of lignans continue to attract the interest of the pharmaceutical industry owing to their remarkable biological benefits, particularly for their anti-tumor and antiviral properties. Arylnaphthalene lignans (ANLs) belong to 6,7'-cyclolignans which contain a 2,3-dimethyl-1-phenyl-naphthalene core structure. ANLs are widely distributed in plants. Justicia cf. patentiflora was identified as an anti-HIV (human immunodeficiency virus) plant lead through the screening of more than 3,500 plant extracts. Bioassay-directed fractionation of the methanol extract of the stems and barks of this plant has led to the isolation of three ANL glycoside compounds, which displayed potent inhibitory activity against broad HIV clinical strains with EC50 values in the range of 14-37 nM [Zidovudine (AZT): 77-95 nM]. They also showed significant inhibitory effects against drug-resistance HIV strains. Thus, the ANL glycosides have high potential as lead molecules for the development of new therapeutic drugs for HIV/AIDS. Objectives: 1) To establish an efficient route for the total synthesis of ANL compounds and to synthesize a library of ANL compounds through the established total synthetic approach; 2) To evaluate the cytotoxicities and anti-HIV activities of the synthesized ANLs; 3) To elucidate the structure activity relationship (SAR) of ANLs as a basis for the optimization of drug efficacy, improvement of pharmacokinetic properties as well as minimization of the toxicity of ANLs; 4) To synthesize potent anti-HIV ANL molecules with high selectivity. Methods: To achieve these objectives, a synthetic route for ANL was designed and a broad series of ANL derivatives were synthesized via modifications of rings A and B, as well as the functionalities at C-7. The synthesized compounds had been evaluated for their toxicity and antiviral activities. Cytotoxicity was determined using the SRB (Sulforhodamine B) assay, while anti-HIV activity was evaluated by utilizing the "One-Stone-Two-Birds" protocol. Results: We have accomplished the total synthesis of the key intermediate diphyllin with more than 20 g. Our modification of ANL derivatives focused on substitutions, additions and different configurations of the C-7 position, ring A and ring B. Specifically, the different structural components of the ANLs were systematically modified, resulting in the formation of six groups of compounds. A total of 72 ANL compounds with various functional groups were synthesized. Their structures have been confirmed by the MS and NMR spectral data. All the synthesized ANL compounds were purified to have purity ≥ 95%. The SAR of ANL compounds was revealed based on the analysis of the antiviral and cytotoxicity data of these synthetic analogues. After structural modification, all the modified derivatives based on rings A and B (groups 1 and 2) showed activity reduction in terms of both cytotoxic and anti-HIV activities. However, the modification of C-7 yielded divergent results, which included the groups of 3-6. Most compounds in groups 3-5 displayed comparable inhibitory effect with diphyllin (5). Group 6 represents the largest number of analogues among the six groups. In this group, the stereochemical properties and functionalization of the hydroxy groups on the sugar units are essential for their activities. Among these series of derivatives, compound 17b showed significant high potency of anti-HIV activity with an EC50 value of 2.6 nM and SI of 815. Conclusion: Using the synthesized diphyllin as the key intermediate, a compound library of 72 ANL derivatives was obtained. These compounds have been evaluated for their cytotoxicity and anti-HIV activity. Our bioactivity data revealed that the functionalization of the C-7 hydroxy group could significantly reduce the cytotoxicity and increase anti-HIV activity, while the modification on rings A and B would rather result in the reduction of both cytotoxicity and anti-HIV activity. Subsequently, novel diphyllin glycosides containing various sugar moieties were further synthesized. Several of these ANL analogues showed high anti-HIV activity with EC50 values in the nM range and low cytotoxicity (selective indices > 500). Future Perspective: This study clearly suggests ANLs as anti-HIV lead compounds and they have high potential to be developed as therapeutic drugs for the treatment of HIV. To further confirm the antiviral potential of ANLs, live HIV strains including some drug resistant strains should be further investigated. Although our data have shown that the ANL compounds are targeting the viral post-entry stages, their antiviral molecular targets are still unknown. However, since our SAR information has clearly revealed that the substitution of rings A and B are not involve in the antiviral activity for enhancing ANL compounds, the carbon positions in these rings may be explored to link a biotin unit, which can be used as a viable approach to pull down the antiviral target proteins of ANLs. Once the target proteins are identified, molecular docking is then made possible for a rational synthetic design to fine tune the chemical structures of ANLs in order to improve their antiviral properties such as high antiviral activity, low toxicity and enhanced water solubility. A further step to advance ANLs as anti-HIV drugs is the investigation of their drug properties in in vivo studies including the assessment of their anti-HIV efficacy in the rhesus model as well as obtaining their pharmacokinetic and safety parameters. These studies will help to provide more evidence about the anti-viral properties of ANLs
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Pinheiro, Francisca Gleyciara Cavalcante. "Lignosulfonates production from lignin extracted sugarcane bagasse." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13799.
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Universidade Federal do CearÃThe present work aimed at the production of lignosulfonate, based in the lignin extracted from sugarcane bagasse-cane for using in phenolic resins. The extraction of lignin was carried out using the acetosolv process, which was optimised with a central composite design 22 to evaluate the effects of reaction time and temperature on the extraction yield, weight-average (M ̅w) and number-average (M ̅n) molecular weights, relative content of total hydroxyl, phenolic hydroxyl and methoxyl groups. The lignins obtained under conditions that maximized the extraction yield and showed better structural and thermal characteristics were sulfonated to obtain the lignosulfonates. The structural and thermal characteristics of the lignins and lignosulfonates were determined by FT-IR, GPC, 1H-NMR and 13C-NMR, DSC and TGA. The results show that the best extraction yield (64.5%) was obtained with 95% (w/w) of acetic acid, the addition of 0.1% HCl, at a temperature of 187 ÂC and reaction time of 40 min. However, with the same concentration of acetic acid and reaction time of 15 min at 187 ÂC, the extraction yield decreased to 55.6% Â 4.5%, without significant reduction. Furthermore, the increase in temperature of 187 ÂC to 205 ÂC was not enough to cause a significant increase in the relative content of hydroxyls and reduction of the relative content of methoxyl. These results show that the most appropriate conditions for adequate extraction of lignin for application in resins are: 95% (w/w) of acetic acid, addition of 0.1% of HCl, temperature of 187 ÂC and reaction time of 15 min. The acetosolv lignins showed p-hidroxifenila units as major constituent, higher thermal stability and higher purity than the commercial Kraft lignin. The glass transition temperature of the Kraft lignins was lower than that of the acetosolv lignin. This is due to the hydrophilic character and the presence of carbohydrates in the Kraft lignin. The lignosulfonates obtained in this study showed structural characteristics suitable for application in phenolic resins, because they showed high reactivity due to the greater presence of p-hidroxifenila units as major constituent, low molecular weights (40234878 g/mol), greater stability and greater purity compared to commercial sodium lignosulfonate. Therefore, lignosulfonates obtained in this work are more suitable for use in phenolic resins than commercial sodium lignosulfonate used for comparison.
O presente trabalho teve por objetivo a produÃÃo de lignossulfonato, a partir da lignina extraÃda do bagaÃo da cana-de-aÃÃcar para aplicaÃÃo em resinas fenÃlicas. Foi realizada a otimizaÃÃo da extraÃÃo da lignina do bagaÃo de cana-de-aÃÃcar utilizando o processo acetosolv. Para tanto, empregou-se um delineamento composto central 22 para analisar os efeitos do tempo de reaÃÃo e da temperatura no rendimento de extraÃÃo, massa molar ponderal mÃdia, massa molar numÃrica mÃdia, e conteÃdo relativo de hidroxilas totais, hidroxilas fenÃlicas e metoxilas. As ligninas obtidas nas condiÃÃes que maximizaram o rendimento de extraÃÃo e que mostraram melhores caracterÃsticas estruturais e tÃrmicas foram sulfonadas para obtenÃÃo dos lignossulfonatos. As caracterÃsticas estruturais e tÃrmicas das ligninas e dos lignossulfonatos foram determinadas por FT-IR, GPC, RMN-1H e 13C, TGA e DSC. Os resultados mostram que o melhor rendimento de extraÃÃo (64,5 % 4,2%) foi obtido com 95% (m/m) de Ãcido acÃtico, adiÃÃo de 0,1% de HCl, a uma temperatura de 187 C e tempo de reaÃÃo de 40 min. No entanto, com a mesma concentraÃÃo de soluÃÃo de Ãcido acÃtico e com tempo de reaÃÃo de 15 min a 187ÂC, o rendimento de extraÃÃo diminuiu para 55,6%  4,5%, nÃo sendo significativa esta reduÃÃo. AlÃm disto, a elevaÃÃo da temperatura de 187ÂC para 205ÂC nÃo foi suficiente para causar um aumento significativo no conteÃdo relativo de hidroxilas e reduÃÃo do conteÃdo relativo de metoxila. Esses resultados mostram que as condiÃÃes mais adequadas para extraÃÃo da lignina a ser aplicada em resinas sÃo: 95% (m/m) de Ãcido acÃtico, adiÃÃo de 0,1% de HCl, temperatura de 187 C e tempo de reaÃÃo de 15 min. As ligninas acetosolv apresentaram unidades p-hidroxifenila como constituinte majoritÃrio, maior estabilidade tÃrmica e maior pureza em relaÃÃo à lignina Kraft comercial. A temperatura de transiÃÃo vÃtrea da lignina Kraft foi menor do que à das ligninas acetosolv, devido à sua caracterÃstica hidrofÃlica e à presenÃa de carboidratos na lignina Kraft. Os lignossulfonatos obtidos no presente trabalho apresentaram caracterÃsticas estruturais adequadas para aplicaÃÃo em resinas fenÃlicas, pois mostraram alta reatividade devido a maior presenÃa de unidades p-hidroxifenila como constituinte majoritÃrio, baixas massas molares (4023 a 4878 g/mol), maior estabilidade e uma maior pureza em relaÃÃo ao lignossulfonato de sÃdio comercial. Portanto, os lignossulfonatos obtidos no presente trabalho sÃo mais adequados para aplicaÃÃo em resinas fenÃlicas do que o lignossulfonato de sÃdio comercial utilizado no presente trabalho.
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Bartley, Paul Andrew. "Experimental investigation of the sand-stabilization potential of a plant-derived bio-mass." Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/13133.
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Master of ScienceDepartment of Civil Engineering
Dunja Peric
The main objective of this study was to experimentally investigate the Mohr-Coulomb strength parameters of masonry sand mixed with varying amounts of water and lignin. Lignin is a plant-derived biomass, which is a co-product of bio-fuel production. It exhibits binding qualities when mixed with water thus making it an ideal candidate for sustainable non-traditional sand stabilization. An experimental program was devised and carried out to quantify the compaction and early age stress-strain and dilatancy responses of sand-lignin mixes. The program included sieve analysis, Atterberg limit tests, standard Proctor tests, and direct shear tests. The experimental results were used to find the cohesion and the angle of internal friction of the tested material, therefore determining the influence of the amount of lignin and water on the strength of the samples. An extensive data analysis was subsequently completed to gain deeper understanding of the underlying strength gain mechanism. It was found that the normalized cohesion benefit due to lignin is controlled by two variables; water to lignin ratio and void ratio. The lignin and water create a paste, which provides particle bonding at the contacts of sand particles, thus increasing the stress-bearing cross sectional area. Increase in the portion of cross-sectional area occupied by water and lignin normalized by gravimetric lignin content, increases the normalized cohesion up to a point, while the cohesion per gravimetric lignin content decreases with the increasing area ratio. This in turn indicates that cohesion increases only up to 6% of lignin, beyond which it starts to decrease due to the presence of too much fine material within the pores. The presence of lignin in the pores consistently decreases the angle of internal friction. However, for all configurations with lignin tested herein, cohesion was larger than for dry sand, thus indicating strength benefits at low confining pressures or at normal stresses below the so-called limiting normal stress.
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Lee, Yun. "Computational modeling reveals new control mechanisms for lignin biosynthesis." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45774.
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Lignin polymers provide natural rigidity to plant cell walls by forming complex molecular networks with polysaccharides such as cellulose and hemicellulose. This evolved strategy equips plants with recalcitrance to biological and chemical degradation. While naturally beneficial, recalcitrance complicates the use of inedible plant materials as feedstocks for biofuel production. Genetically modifying lignin biosynthesis is an effective way to generate varieties of bioenergy crops with reduced recalcitrance, but certain lignin-modified plants display undesirable phenotypes and/or unexplained effects on lignin composition, suggesting that the process and regulation of lignin biosynthesis is not fully understood. Given the intrinsic complexities of metabolic pathways in plants and the technical hurdles in understanding them purely with experimental methods, the objective of this dissertation is to develop novel computational tools combining static, constraint-based, and dynamic, kinetics-based modeling approaches for a systematic analysis of lignin biosynthesis in wild-type and genetically engineered plants. Pathway models are constructed and analyzed, yielding insights that are difficult to obtain with traditional molecular and biochemical approaches and allowing the formulation of new, testable hypotheses with respect to pathway regulation. These model-based insights, once they are verified experimentally, will form a solid foundation for the rational design of genetic modification strategies towards the generation of lignin-modified crops with reduced recalcitrance. More generically, the methods developed in this dissertation are likely to have wide applicability in similar studies of complex, ill-characterized pathways where regulation occurring at the metabolic level is not entirely known.
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Sjöberg, Gudrun. "Lignin degradation : long-term effects of nitrogen addition on decomposition of forest soil organic matter /." Uppsala : Dept. of Soil Sciences, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/a419.pdf.
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Liu, Zhenhua. "Evolutionary mechanisms of plant adaptation illustrated by cytochrome P450 genes under purifying or relaxed selection." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAJ008.
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Les plantes produisent une remarquable diversité de métabolites pour faire face aux contraintes d’un environnement en constante fluctuation. Cependant la manière dont les plantes ont atteint un tel degré de complexité métabolique et les forces responsables de cette diversité chimique reste largement incomprise. On considère généralement que le mécanisme de duplication des gènes contribue pour une grande part à l’évolution naturelle. En absence de transfert horizontal, les gènes d’évolution récente se cantonnent généralement chez quelques espèces et sont soumis à une évolution rapide, alors que les gènes conservés et plus anciens ont une distribution beaucoup plus large et sont porteurs de fonctions essentielles. Il est donc intéressant d’étudier l’adaptation des plantes en analysant parallèlement les gènes qui présentent soit une large distribution taxonomique, soit une distribution plus restreinte, de type lignée-spécifique. Les cytochromes P450 (CYP) constituent l’une des plus vastes familles de protéines chez les plantes, présentant des phylogénies très conservées ou très branchées qui illustrent la plasticité métabolique et la diversité chimique. Pour illustrer l’évolution des fonctions des cytochromes P450 dans le métabolisme végétal, nous avons sélectionné trois gènes, l’un très conservé au cours de l’évolution, CYP715A1 et les deux autres, CYP98A8 et CYP98A9, très récemment spécialisés de manière lignée spécifique chez les Brassicaceae. Les gènes appartenant à la famille CYP715 ont évolué avant la divergence entre gymnospermes et angiospermes, et sont le plus souvent présent en copie unique dans les génomes végétaux. Ceci suggère que leur fonction est essentielle et très conservée chez les plantes à graines (spermaphytes). Sur la base d’une analyse transcriptionnelle et de l’expression du gène GUS sous le contrôle du promoteur de CYP715A1, il est apparu que ce gène est spécifiquement exprimé au cours du développement floral, dans les cellules tapétales des jeunes boutons floraux ainsi que dans les filaments lors de l’anthèse. CYP715A1 est également fortement induit dans les cellules du péricycle de la zone d’élongation racinaire en réponse au stress salin. L’induction par le sel nécessite une région promotrice située entre 2 et 3 kb en amont de la région codante (i.e ; codon START), ce qui suggère la présence d’un facteur cis à cet endroit. Afin de déterminer la fonction de CYP715A1 chez Arabidopsis thaliana, j’ai identifié deux mutants d’insertion de T-DNA par génotypage et complémenté ces mutants avec le gène natif. La perte de fonction de CYP715A1 n’a pas d’impact sur la croissance et la fertilité de la plante en conditions de laboratoire. Cependant, une analyse par microscopie électronique en transmission montre un phénotype d’intine ondulée. La perte de fonction du gène CYP715A1 a également entraîné une réduction de la taille des pétales et un défaut d’anthèse. [...]Plants produce a remarkable diversity of secondary metabolites to face continually challenging and fluctuating environmental constraints. However, how plants have reached such a high degree of metabolic complexity and what are the evolutionary forces responsible for this chemodiversity still remain largely unclarified. Gene evolution based on gene birth and extinction has been reported to nicely reflect the natural evolution. Without horizontal gene transfer, young genes are often restricted to a few species and have undergone rapid evolution, whereas old genes can be broadly distributed and are always indicative of essential housekeeping functions. It is thus of interest to study plant adaptation with parallel focus on both taxonomically widespread and lineage-specific genes. P450s are one of the largest protein families in plants, featuring both conserved and branched phylogenies. Examples of P450 properties reflecting metabolic versatility, chemodiversity and thus plant adaptation have been reported. To illustrate evolution of P450 functions in plant metabolism, we selected two P450 genes, one evolutionary conserved CYP715A1 and the second a recently specialized lineage-specific gene CYP98A9 in Arabidopsis thaliana.CYP715s evolved before the divergence between gymnosperms and angiosperms and are present in single copy in most sequenced plant genomes, suggesting an essential housekeeping function highly conserved across seed plants. Based on transcriptome analysis and promoter-driven GUS expression, CYP715A1 is selectively expressed in tapetal cells of young buds and filaments of open flowers during flower development. In addition, CYP715A1 is highly induced in the pericycle cells of the root elongation zone upon salt stress. The salt induction relies on the 2-3kb region of CYP715A1 promoter, suggesting some salt-response elements may exist in this area. To characterize the function of CYP715A1 in Arabidopsis, I identified two T-DNA insertion mutants by genotyping and confirmed by complementation with native CYP715A1 gene. Loss of function of CYP715A1 has no impact on plant growth and fertility in laboratory conditions. However, transmission electron microscopy (TEM) analysis has shown constant undulated intine phenotype in two knockout mutants and also the petal growth is significantly inhibited. These two phenotypes nicely match the native expression pattern of CYP715A1. Gene co-expression analysis suggests involvement of CYP715A1 in gibberellin (GA) metabolism under salt treatment. GAs profiling on mutant flowers also indicates reduced accumulation specific GAs. Unfortunately, no significant phenotype either related to root growth or root architecture under salt treatment can be observed. Recombinant expression of the CYP715A1 enzyme in yeast so far does not allow confirming GAmetabolism. However, metabolic profiling of inflorescences in mutants and over-expression lines, together with transcriptome analysis of the loss of function cyp715a1 mutants strongly support a CYP715A1 role in signaling, hormone homeostasis and volatile emission in agreement with the purifying selection leading to gene conservation observed in spermatophytes.[...]
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Vanneuville, Hugo. "Percolation dans le plan : dynamiques, pavages aléatoires et lignes nodales." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1262/document.
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Dans cette thèse, nous étudions trois modèles de percolation planaire : la percolation de Bernoulli, la percolation de Voronoi, et la percolation de lignes nodales. La percolation de Bernoulli est souvent considérée comme le modèle le plus simple à définir admettant une transition de phase. La percolation de Voronoi est quant à elle un modèle de percolation de Bernoulli en environnement aléatoire. La percolation de lignes nodales est un modèle de percolation de lignes de niveaux de champs gaussiens lisses. Deux fils conducteurs principaux ont guidé nos travaux. Le premier est la recherche de similarités entre ces modèles, en ayant à l'esprit que l'on s'attend à ce qu'ils admettent tous la même limite d'échelle. Nous montrons par exemple que le niveau critique de la percolation de lignes nodales est égal au niveau auto-dual (à savoir le niveau zéro) lorsque le champ considéré est le champ de Bargmann-Fock, qui est un champ gaussien analytique naturel. Le deuxième fil conducteur est l'étude de dynamiques sur ces modèles. Nous montrons en particulier que, si on considère un modèle de percolation de Voronoi critique et si on laisse les points se déplacer selon des processus de Lévy stables à très longue portée, alors il existe des temps exceptionnels avec une composante non bornéeWe study three models of percolation in the plane: Bernoulli percolation, Voronoi percolation, and nodal lines percolation. Bernoulli percolation is often considered as the simplest model which admits a phase transition. Voronoi percolation is a Bernoulli percolation model in random environment. Nodal lines percolation is a level lines percolation model for smooth planar Gaussian fields. We have followed two main threads. The first one is the resarch of similarities between these models, having in mind that we expect that they admit the same scaling limit. We show for instance that the critical level for nodal lines percolation is the self-dual level (namely the zero level) if the Gaussian field is the Bargmann-Fock field, which is natural analytical field. The second main thread is the study of dynamics on these percolation models. We show in particular that if we sample a critical Voronoi percolation model and if we let each point move according to a long range stable Lévy process, then there exist exceptional times with an unbounded cluster
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Mustafayeva, Khuraman. "Etude d'une plante endémique du Caucase : cephalaria kotschyi." Aix-Marseille 2, 2009. http://www.theses.fr/2009AIX22955.
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Alber, Annette Veronika. "Phenolic 3-hydroxylases in land plants : biochemical diversity and molecular evolution." Thesis, Strasbourg, 2016. http://hdl.handle.net/1828/7651.
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Plants produce a rich variety of natural products to face environmental constraints. Enzymes of the cytochrome P450 CYP98 family are key actors in the production of phenolic bioactive compounds. They hydroxylate phenolic esters for lignin biosynthesis in angiosperms, but also produce various other bioactive phenolics. We characterized CYP98s from a moss, a lycopod, a fern, a conifer, a basal angiosperm, a monocot and from two eudicots. We found that substrate preference of the enzymes has changed during evolution of land plants with typical lignin-related activities only appearing in angiosperms, suggesting that ferns, similar to lycopods, produce lignin through an alternative route. A moss CYP98 knock-out mutant revealed coumaroyl-threonate as CYP98 substrate in vivo and showed a severe phenotype. Multiple CYP98s per species exist only in the angiosperms, where we generally found one isoform presumably involved in the biosynthesis of monolignols, and additional isoforms, resulting from independent duplications, with a broad range of functions in vitroGraduate
2017-08-31
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Horstmann, Carl Ulrich. "Manipulating cell wall biosynthesis in yeast and higher plants." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5288.
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Thesis (MSc (Genetics))--University of Stellenbosch, 2010.Includes bibliography.
Title page: Dept. of Genetics, Faculty of Science.
ENGLISH ABSTRACT: Undeniably, changes in the environment and dwindling traditional energy resources have resulted in the search for viable, renewable energy alternatives such as biofuels. Cellulose is one of the most abundant polymers on earth and can be converted to simple sugars and fermented to ethanol biofuel fairly easily. Cellulose rich biomass that can serve to supply ethanol biofuel production can be sourced from unexploited agricultural waste. The main drawback to using vegetative tissue as opposed to harvested food stocks from crops results from the structural properties of plant cell walls. Although cellulose is abundant, the contaminating hemicellulose and lignin fibres within the cell wall matrix have a negative impact on the digestibility of the cellulose present. Thus, an important step in creating an effective biofuel production system from agricultural excess is developing crops with improved cell wall polymer characteristics that can be converted to ethanol more efficiently. This project consisted of two parts. Firstly, the aim was to assess lignin production in transgenic sugarcane transformed with a construct aimed at down-regulating the 4- (hydroxyl) cinnamoyl CoA ligase (4CL) gene in the lignin biosynthesis pathway. The second part of the project revolved around discovering the mechanism of impared cell growth caused by expressing the gene encoding cellulose synthase from a marine invertebrate, Ciona savignyi, in the yeast Saccharomyces cerevisiae. Several sugarcane lines that had been previously transformed with a hairpin RNAi construct aimed at down-regulating the 4CL gene in the monolignol biosynthesis pathway were subjected to analysis to determine if lignification had been reduced. Although the presence of the hairpin construct in the genomic DNA had been confirmed for all of the transgenic lines, there was no significant decrease in the lignin levels in any of the transgenic lines. PCR analysis of the mRNA and enzyme assays also confirmed that the 4CL gene was still being expressed. Ongoing work will determine the cause of the unsuccessful down-regulation. Previously, it had been proven that the cellulose synthase gene from C. savignyi could be functionally expressed in S. cerevisiae. However, cellulose production resulted in extremely retarded growth of colonies and cultures, to the point of the apparent death of the cultures. The aim of this part of the project was to determine the mechanism (either metabolic or physical) that causes this effect. To generate enough cell mass to perform metabolic analysis, several strategies to impede cellulose production in transgenic yeast were explored. Attempts to stop cellulose production and induce better growth by introducing Isoxaben (a traditional weed killer that targets cellulose synthases) into the growth medium used for the transgenic yeast proved unsuccessful. To control the expression of the transgene, it was attempted to clone the cellulose synthase gene into an expression system containing an inducible promoter. The cloning exercise proved extremely difficult and multiple attempts with several strategies proved unsuccessful. This process is still ongoing as the growth retarding process induced by cellulose production in yeast remains to be identified.
AFRIKAAANSE OPSOMMING: Dit is onontkenbaar dat veranderinge in die omgewing en minderwordende tradisionele energiebronne veroorsaak dat lewensvatbare en hernubare energiebronne soos biobrandstof gevind moet word. Sellulose is een van die mees volop polimere op aarde en kan redelik maklik omgeskakel word na eenvoudige suikers en gefermenteer word tot etanol-biobrandstof. Sellulose-ryk biomassa wat etanol-biobrandstof kan verskaf, kan herwin word van tot op hede ongebruikte landbou-afval. Die komplekse struktuur van plantselwande is die hoofstruikelblok in die omskakeling van vegetatiewe weefsel tot biobrandstof. Hoewel sellulose volop is, het die kontaminerende hemisellulose- en lignienvesels binne die selwand-matriks ’n negatiewe impak op die verteerbaarheid van die sellulose teenwoordig in die selwand. Daarom is ’n belangrike stap in die ontwikkeling van effektiewe biobrandstof-produksiesisteme vanaf landbou-afval om gewasse te ontwikkel met verbeterde selwandpolimeer-eienskappe wat etanol-produksie kan vergemakilik. Hierdie projek het bestaan uit twee dele. Eerstens was die doel om vas te stel of die lignienproduksie geaffekteer is in transgeniese suikerriet getransformeer met ’n konstruk wat mik om die 4-(hidroksie)-cinnamoyl CoA ligase (4CL) geen te af-reguleer in die lignienbiosintese- padweg. Die tweede deel van die projek het daarop gefokus om die meganisme te ondek wat die belemmerde selgroei veroorsaak, as gevolg van die uitdrukking van die geen wat kodeer vir sellulose-sintase in ’n mariene ongewerwelde, Ciona savignyi, in Saccharomyces cerevisiae. Verskeie suikerriet-lyne, wat voorheen getransformeer is met ’n haarnaald-RNAi-konstruk om die 4CL-geen te af-reguleer in die monolignol-biosintese-padweg, is onderwerp aan analise om vas te stel of lignifikasie verminder is. Hoewel die teenwoordigheid van die haarnaald-konstruk in die genomiese DNA bevestig is vir al die transgeniese lyne, was daar geen beduidende vermindering in die lignienvlakke in die transgeniese lyne nie. PKRanalise van die mRNA en ensiem-aktiwiteitstoetse het ook bevestig dat die 4CL-geen steeds uitgedruk word. Verdere ondersoek sal kan vasstel wat die oorsaak van die onsuksesvolle af-regulering is. Voorheen is bewys dat die sellulose-sintase-geen van C. savignyi funksioneel uitgedruk kon word in Saccharomyces cerevisiae. Egter, selluloseproduksie het die gevolg gehad dat groei in die transgeniese kolonies en kulture erg gestrem is, tot die punt dat die kulture dood voorgekom het. Die doel van hierdie deel van die projek was om vas te stel wat die meganisme (òf metabolies òf fisies) is wat hierdie verskynsel veroorsaak het. Om genoeg selmassa te genereer om metaboliese analise uit te voer, is verskeie strategieë om selluloseproduksie in transgeniese gis te verhinder, ondersoek. Pogings om selluloseproduksie te stop en om groei te verbeter deur Isoxaben by te voeg in die groeimedium gebruik vir transgeniese gis, was onsuksesvol. Isoxaben is ’n tradisionele onkruiddoder wat sellulose-sintases teiken en inhibeer. Om die uitdrukking van die transgeen te beheer, is ’n poging aangewend om dié sellulose-sintase-geen in ’n uitdrukking-sisteem te kloon met ’n induseerbare promotor. Die kloneringsoefening was uiters moeilik en veelvoudige pogings met verskeie strategieë was onsuksesvol. Hierdie proses moet verder gevoer word aangesien die groeistremmingsmeganisme veroorsaak deur selluloseproduksie in gis nog geïdentifiseer moet word.
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Pinto, Francisco das Chagas Lima. "Contribution to the knowledge of chemical plants of northeast Brazil: Solanum buddleifolium SENDTN." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=11092.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorThis work describes the chemical study of Solanum buddleifolium (Solanaceae) aimed the isolation and structural characterization of its secondary metabolites. The chemical prospection was realized using chromatographic techniques such as chromatography over silica gel Sephadex LH-20 and solid phase extraction (SPE) besides High Performance Liquid Chromatography (HPLC) From EtOH were isolated the known compounds β-sitosterol and estigmasterol betulinic acid 13-hidroxysolavetrivone polistachiol N-trans-feruloyltiramine N-cis-Feruloyltiramine N-trans-feruloyl-3-methyldopamine N-trans-coumaroyltiramine N-trans-caffeoyltiramine N-trans-feruloyldopamine (+)-lioniresinol (-)-lioniresinol (+)-3-metoxisolariciresinol and the alkaloid solamargine alangilignoside C and ligalbumoside A (+)-alangilignoside D and (-)-alangilignoside D β-sitosterol glucoside and N-trans-caffeoyldopamine The structures of all compounds were determined by using spectrometric techniques (IR MS and 1H and 13C NMR) including 2D experiments (COSY HSQC HMBC and NOESy) and comparison with published data This is the first report about S. buddleifolium All lignans are been described for the first time in the genus Solanum and consequently represent an important contribution for the chemiotaxonomy of the genus
Este trabalho descreve o estudo quÃmico realizado com Solanum buddleifolium (Solanaceae) visando o isolamento e a caracterizaÃÃo estrutural de seus metabÃlitos secundÃrios A investigaÃÃo quÃmica do extrato etanÃlico dos talos da referida espÃcie foi realizada atravÃs de tÃcnicas cromatogrÃficas cromatografia em gel de sÃlica e por exclusÃo molecular (Sephadex L-20) cromatografia por extraÃÃo em fase sÃlida (SPE) e Cromatografia LÃquida de Alta EficiÃncia (CLAE) Do procedimento de extraÃÃo Ãcido/base da fraÃÃo hidroalcoÃlica do extrato etanÃlico foram isolados (+)-lioniresinol (SB-1) (-)-lioniresinol (SB-2) (+)-3-metoxisolariciresinol (SB-3) e o alcalÃide solamargina (SB-4) Da fraÃÃo diclorometano do extrato etanÃlico dos talos de S. buddleifolium foram isolados e caracterizados os seguintes compostos β-sitosterol (SB-5A) e estigmasterol (SB-5B) Ãcido betulÃnico (SB-6) 13-hidroxisolavetivona (SB-7) polistachiol (SB-8) N-trans-feruloiltiramina (SB-9A) N-cis-feruloiltiramina (SB-9B) N-trans-feruloil-3-metildopamina (SB-10) N-trans-coumaroiltiramina (SB-11) N-trans-caffeoiltiramina (SB-12) N-trans-feruloildopamina (SB-13) o glicosÃdeo do β-sitosterol (SB-14) alangilignoside C (SB-15A) e ligalbumoside A (SB-15B) (+)-alangilignoside D (SB-16A) e (-)-alangilignoside D (SB-16B) e N-trans-cafferoildopamina (SB-17) As estruturas de todos os compostos foram determinadas com base em tÃcnicas espectromÃtricas (IV EM-IES e RMN 1H e 13C 1D e 2D) alÃm de comparaÃÃo com dados jà registrados na literatura. Este à o primeiro estudo envolvendo S. buddleifolium e todas as lignanas caracterizadas estÃo sendo descritas pela primeira vez no gÃnero Solanum representando uma importante contribuiÃÃo para o conhecimento quÃmico deste
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Cecanho, Fernanda França. "Composição da matéria orgânica nos sedimentos superficiais da várzea do lago grande de Curaí, Pará, Brasil." Niterói, 2018. https://app.uff.br/riuff/handle/1/5819.
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Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geoquímica, Niterói, RJ
A abordagem utilizada neste estudo visou caracterizar a composição da matéria orgânica no sedimento superficial dos diferentes lagos (águas brancas e pretas) que compõe a Várzea do Lago Grande de Curuai, através dos fenóis oriundos da lignina como traçador de plantas vascularizadas, e dados secundários de análises isotópicas ( 13C) e elementares (C/N), em amostras de sedimento superficial e de possíveis fontes de matéria orgânica. A caracterização dos fenóis de lignina nas amostras de sedimento para as possíveis fontes de matéria orgânica (plantas terrestres, macrófitas e perifiton) e para o sedimento foram feitas através da degradação oxidativa em meio básico com óxido de cobre (CuO). Das amostras de fontes de MO analisadas, Echinocloa polystachia (Capim Canarana) com maior razão S/V e Capim (nd) com maior razão C/V foram as que mais mostraram contribuição na composição da MO para os sedimentos superficiais, mostrando a grande contribuição de MO autóctone macrofítica e fitoplanctônica para a várzea do Lago Grande de Curuai. Os resultados obtidos com os fenóis oriundos da lignina apontam característica de vegetação terrestre, com elevada razão S/V para a amostra de fonte de MO Echinocloa spectabilis (Mutim), caracterizada como fonte alóctone de matéria orgânica para o sedimento da várzea, correspondendo á vegetação C4 terrestre. Gramínea (nd), Pistia stratiotes (Alface d’Água), Eichornia azurea (Mureru) e Eichornia crassipes correspondem a fonte autóctone de matéria orgânica para o sedimento da várzea apresentando elevados valores de razão C/V; e a amostra de Epifiton caracterizou-se como uma mistura de fontes fitoplanctônica, macrofítica e de vegetação terrestre para os sedimentos da várzea. Os resultados obtidos para as amostras de sedimento superficial mostram que a proximidade com terras florestadas, o grau de interferência do Rio Amazonas, e de interconexão entre os lagos que compõe a várzea do Lago Grande de Curuai, interferem na composição (alóctone ou autótone), e no grau de decomposição da MO depositada no sedimento. Os lagos de águas pretas Curumucuri e Açaí apresentaram grande contribuição de MO alóctone da drenagem do solo da floresta adjacente, mas com diferenças no grau de decomposição; sendo que para o Açaí com pouca interferência do Amazonas e isolado dos demais lagos da várzea a MO encontrada no sedimento apresenta maior degradação, enquanto que para o Lago Curumucuri, mais interligado ao sistema, a MO depositada no sedimento é menos degradada. A composição da matéria orgânica para o sedimento dos lagos de águas brancas apresenta maior influência de MO autóctone (vegetação aquática), com exceção do Lago Salé que apresenta grande influência de MO alóctone proveniente da floresta adjacente e do Rio Amazonas. Existem diferenças no grau de decomposição da MO nos lagos de águas brancas, sendo que para os pontos em maior contato com o rio Amazonas a MO no sedimento encontra-se menos degradada.
The approach applied in this study focused in characterizes the organic matter composition in plants and sediments of Várzea do Lago Grande do Curuai floodplain among white water and black water lakes. As a vascular plant tracer it was used lignin phenol composition through cupric oxide degradation under basic conditions analysis. To a better interpretation it was used a secondary data from elemental (C/N) and isotopic ( 13C) analysis. The results from possible organic matter sources to lake sediments, showed higher amount of a non-leaf origin indicated by syringyl phenol ratio normalized to vanillin (S/V) to Echinocloa spectabilis (Mutim); Echinocloa polystachia (Capim Canarana) and Capim (non-identified). However, higher value of C/V ratio coupled to the high S/V values found to Echinocloa polystachia (Capim Canarana) was related to its aquatic behavior allowing a more leaf growth against a terrestrial type as Echinocloa spectabilis (Mutim) with a more structure phenol necessity typical of a terrestrial grass. The Gramínea (ni), Pistia stratiotes (Alface d’Água) and Eichornia crassipes samlpes presented higher C/V ratios values, characterizing a more leaf material typical of aquatic plants. The epiphyton sample indicated a mixture composed by both aquatic and terrestrial plants. Those alochthone versus autochthones sources added to the degradation conditions determined the composition of organic matter deposited. The superficial sediments samples results appeared to be influenced by the forest low land proximity, the Amazon River influence and by the interconnection among the productivity of the floodplain lakes. The black water lakes Curumucuri e Açaí presented a high alochthone organic matter contribution from the drainage of the neighborhood forest. Differences found in degradation rates were related to the hydrological function of those black water lakes. Açai lake showed a higher degradation rate in relation to Cumurucuri Lake that presented a less degraded organic matter due to a higher influence from floodplain system. The organic matter from white water lakes sediments presented a high autochthones proximate sources (aquatic plants) and less alochthone ultimate source (terrestrial plants). Exception were found to Sale Lake with the influence of the neighborhood forest drainage and also from the contact of Amazon River. Among white water lakes, Lago Grande de Curuai, Poção, Santa Ninhã, Salé e Lago Grande do Poção, it was found differences in degradation rates, related with water circulation, where a more Amazon River influence showed a less degraded rate.
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Escamez, Sacha. "Xylem cells cooperate in the control of lignification and cell death during plant vascular development." Doctoral thesis, Umeå universitet, Institutionen för fysiologisk botanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-115787.
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The evolutionary success of land plants was fostered by the acquisition of the xylem vascular tissue which conducts water and minerals upwards from the roots. The xylem tissue of flowering plants is composed of three main types of cells: the sap-conducting tracheary elements (TE), the fibres which provide mechanical support and the parenchyma cells which provide metabolic support to the tissue. Both the TEs and the fibres deposit thick polysaccharidic secondary cell walls (SCWs), reinforced by a rigid phenolic polymer called lignin. The cell walls of TEs form efficient water conducting hollow tubes after the TEs have undergone programmed cell death (PCD) and complete protoplast degradation as a part of their differentiation. The work presented in this thesis studied the regulation of TE PCD by characterizing the function of the candidate PCD regulator METACASPASE 9 (MC9) in Arabidopsis thaliana xylogenic cell suspensions. These cell suspensions can be externally induced to differentiate into a mix of TEs and parenchymatic non-TE cells, thus representing an ideal system to study the cellular processes of TE PCD. In this system, TEs with reduced expression of MC9 were shown to have increased levels of autophagy and to trigger the ectopic death of the non-TE cells. The viability of the non-TE cells could be restored by down-regulating autophagy specifically in the TEs with reduced MC9 expression. Therefore, this work showed that MC9 must tightly regulate the level of autophagy during TE PCD in order to prevent the TEs from becoming harmful to the non-TEs. Hence, this work demonstrated the existence of a cellular cooperation between the TEs and the surrounding parenchymatic cells during TE PCD. The potential cooperation between the TEs and the neighbouring parenchyma during the biosynthesis of lignin was also investigated. The cupin domain containing protein PIRIN2 was found to regulate TE lignification in a non-cell autonomous manner in Arabidopsis thaliana. More precisely, PIRIN2 was shown to function as an antagonist of positive transcriptional regulators of lignin biosynthetic genes in xylem parenchyma cells. Part of the transcriptional regulation by PIRIN2 involves chromatin modifications, which represent a new type of regulation of lignin biosynthesis. Because xylem constitutes the wood in tree species, this newly discovered regulation of non-cell autonomous lignification represents a potential target to modify lignin biosynthesis in order to overcome the recalcitrance of the woody biomass for the production of biofuels.
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Wong, Quai Lam Mary Sarah-Jane. "Assemblage et dégradation des parois de maïs : de la plante entière à l'échelle cellulaire." Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1406/.
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Le maïs, l'une des plantes les plus cultivées au monde, sert de base dans l'alimentation humaine et des ruminants et pour la production d'agrocarburant. Sa valeur agronomique est principalement liée à la digestibilité des constituants de la paroi cellulaire (sucres, lignines,. . . ). De nombreuses études ont été menées afin d'améliorer la digestibilité de cette paroi, notamment sur la voie de biosynthèse des lignines. Au cours de ma thèse, nous avons démontré, chez le maïs, que la mutation du gène ZmCCR1 (Cinnamoyl-CoA reductase), codant pour une enzyme clé de la voie de biosynthèse des lignines, conduisait à une diminution des unités H associée à une meilleure digestibilité. La deuxième partie de mes recherches a porté sur l'identification des paramètres influençant la digestibilité à l'échelle cellulaire. En effet, il existe chez le maïs une très grande diversité de types cellulaires à paroi lignifiée non seulement entre différents organes, mais également au sein de chaque organe (sclérenchyme, parenchyme, vaisseaux de xylème. . . ). Dans ce but, une étude combinant de multiples techniques biochimique, histologique et transcriptomique, a été réalisée sur deux lignées de digestibilité contrastée. Ainsi, nous avons mis en évidence l'importance de la proportion de tissus lignifiés, plus particulièrement du sclérenchyme périvasculaire. Au-delà, le développement de la microdissection laser (LCM) a permis de souligner la différence de composition des tissus lignifiésMaize is one of the most widely grown crops in the world and is grown for grain for human consumption, feedstock for cattle and more recently biofuel. When used as fuel, the most important agronomic trait is digestibility which is dictated by cell wall composition and structure. Many studies have been undertaken in order to improve cell wall digestibility and have essentially focused on the lignin biosynthetic pathway. During my PhD research, we have shown that a mutation in ZmCCR1 (Cinnamoyl-CoA reductase 1), key enzyme in lignin biosynthesis, modified lignin structure which in turn resulted in an increase in digestibility. Beyond lignification per se, my studies focused on the identification of other potential parameters influencing digestibility at the cellular level. This is especially pertinent in maize since its stem biomass is made up of different several lignified tissues and cell types. By combining cell wall biochemistry on laser microdissected (LMD) lignified tissues, with histological studies, we have been able to show that in highly contrasting lines (Cm484 and F98902) the lignified cell types patterning and in particular, the amount and cell wall composition are critical factors in determining maize digestibility
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Ferreira, Júnior Domingos da Costa. "Teor de lignina e respostas antioxidantes de milho forrageiro sob estresse salino e ácido salicílico exógeno." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/153822.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Muitos estudos apontam que o ácido salicílico (AS) está envolvido na adaptação de plantas a estresses abióticos. Entretanto, pouco se sabe sobre a ação deste hormônio na síntese de importantes metabólitos secundários em condições de estresse, como a lignina. Para tanto, foram estudados neste trabalho os efeitos de AS exógeno no crescimento, lignificação, metabolismo antioxidativo, acúmulo de osmólitos compatíveis e acúmulo de Na+ e macronutrientes em folhas de milho sob concentrações crescentes de NaCl. O delineamento experimental utilizado foi o inteiramente casualizado em esquema fatorial 2x4, representado pelas concentrações de AS (0,0 e 0,5 mM) e concentrações de NaCl (0, 50, 100 e 150 mM). As plantas foram submetidas aos tratamentos no estádio fenológico V4 (quatro folhas completamente desenvolvidas), enquanto que as avaliações foram realizadas no estádio V6 (seis folhas completamente desenvolvidas). Foram avaliados os seguintes parâmetros na parte aérea: área foliar, massa seca, teor de lignina, peroxidação lipídica, teor de peróxido de hidrogênio (H2O2), atividade enzimática da superóxido dismutase (SOD) e catalase (CAT), teor de prolina (Pro) e glicina betaína, relação Na+/K+ e teor de macronutrientes (N, P, Ca, Mg, S). O estresse salino reduziu o crescimento da parte aérea da planta, além de induzir maior acúmulo de Pro e GB, peroxidação lipídica, atividade da CAT e lignificação foliar. A adição de AS à solução nutritiva atenuou o efeito da salinidade sobre o crescimento vegetal até a concentração de 100 mM de NaCl, o que pode estar relacionado à maior lignificação, aumento na atividade da SOD e teores de Pro e H2O2, maior teor de N e Ca, além de reduções nos níveis foliares de Na+ e peroxidação de lipídios. Dessa forma, conclui-se que o AS exógeno atenua os efeitos deletérios de estresse salino baixo e moderado por três vias: maior lignificação foliar, o que pode se relacionar à maior produção de H2O2; menor peroxidação lipídica, relacionada à maior atividade de SOD; e menor teor foliar de Na+, aliado a aumento nos teores de Ca2+ e N.
Several studies demonstrate that salicylic acid (AS) is involved in the adaptation responses of plants to abiotic stresses. However, not much is known about the action of this hormone on the synthesis of important secondary metabolites, as lignin. For this purpose, in this work it was assessed the effects of exogenous application of SA on the growth, lignification, antioxidant metabolism, compatible osmolytes content, and concentration of Na+ and in maize leaves under increasingly NaCl concentrations. It was adopted a completely randomized design and a 2x4 factorial layout, representing SA concentrations (0.0 and 0.5 mM) and NaCl concentrations (0, 50, 100 and 150 mM) in hydroponics. Plants were exposed to the treatments at the V4 phenological stage (with four completely developed leaves), and evaluations were performed at V6 stage (six completely developed leaves). The following parameters were assessed on shoots: leaf area, dry weight, lignin content, lipid peroxidation, enzymatic activity of superoxide dismutase (SOD) and catalase (CAT), proline (Pro) and glycinebetaine (GB) contents, Na+ /K+ ratio and macronutrients concentration (N, P, Ca, Mg and S). Salt stress impaired shoot growth, also inducting higher accumulation of Pro and GB, lipid peroxidation, CAT activity, leaf lignification and also lower content of all evaluated nutrients. The application of AS alleviated the deleterious effects of salinity on maize shoot growth until 100 mM of NaCl, what can be related to an enhancement of SOD activity, lignin, proline and H2O2 contents, higher N and Ca contents, as to lower lipid peroxidation and Na+ content. This way, it is concluded that exogenous AS mitigates the negative effects of low and moderate salt stress on maize through three main ways: higher leaf lignification, which can be correlated with higher H2O2; lower lipid peroxidation, explained by higher SOD activity; and lower Na+ content, followed by increased leaf contents of Ca2+ .
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Kilaru, Aruna, Richard Sante, and Ruth Welti. "Discovery of a Mammalian Endocannabinoid Ligand and Its Metabolites in Early Land Plants." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/4802.
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The endogenous arachidonate-based lipids that activate cannabinoid receptors have been well characterized in mammals. In plants only 12-18 carbon fatty acid ethanolamides have been identifi ed so far and have been shown to modulate a number of physiological processes including seed and seedling development. However, since moss plants contain arachidonic acid, we hypothesized the occurrence of arachidonate-based metabolites in their tissues. Using selective lipidomics approach, we identifi ed the presence of anandamide or arachidonylethanolamide (a 20C polyunsaturated fatty acid ethanolamide) and its precursors, in Physcomitrella patens that were previously not reported in plants. Comprehensive lipid profi les for protonema and gametophyte tissues of moss also revealed the occurrence of other saturated and unsaturated fatty acid ethanolamides and a distinct phospholipid and galactolipid composition. Further studies showed that anandamide, like abscisic acid, inhibits the growth of gametophytes more severely than saturated fatty acid ethanolamides. Our current studies are focused on understanding the physiological and developmental role of polyunsaturated fatty acid ethanolamides in nonseed plants. In conclusion, discovery of anandamide in moss provided us with an exciting possibility to identify fatty acid ethanolamide metabolic pathway in early land plants and elucidate receptor-mediated endocannabinoid signaling responses in plants that is akin to mammals.
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Oliveira, Claudineide Nascimento Fernandes de 1979. "Avaliação in vitro e in vivo da atividade de frações e compostos isolados de Phyllanthus amarus contra o Schistosoma mansoni linhagem BH." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/317491.
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Orientadores: Silmara Marques Allegretti, Vera Lúcia Garcia RehderTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: A propagação da esquistossomose e a ameaça de tolerância e resistência ao fármaco de escolha, o praziquantel, têm intensificado as pesquisas utilizando plantas medicinais com o intuito de promover o desenvolvimento de novos fármacos esquistossomicidas. A planta Phyllanthus amarus (quebra-pedra) possui atividades antiinflamatória e hepatoprotetora já comprovadas cientificamente, o que fez com que a mesma fosse selecionada para este estudo, uma vez que a principal patologia da esquistossomose é a formação de granulomas (processo inflamatório) no fígado. Esse trabalho teve como objetivo fazer um fracionamento biomonitorado do extrato etanólico de P. amarus por meio de ensaios in vitro e in vivo com o intuito de verificar a ação esquistossomicida dessa planta contra o S. mansoni linhagem BH. Para a realização dos testes in vitro, os vermes adultos coletados foram incubados em placas contendo meio de cultura RPMI 1640, um casal de verme e amostras de extrato etanólico bruto, frações de diferentes polaridades ou lignanas isoladas nas concentrações 200, 100, 50 e 25 ?g/mL. Os vermes foram observados por um período de 72 horas, sendo avaliados a taxa de mortalidade, a oviposição, o acasalamento e as alterações tegumentares. A melhor atividade in vitro foi observada com a fração 2 butanólica, pois foi letal para 100% dos vermes em 48 h de observação, sendo assim selecionada para os testes in vivo. A fração 2 butanólica é composta majoritariamente por lignanas, por isso algumas delas (nirantina, filantina + nirantina e filantina + filtetralina + nirtetralina), mesmo não sendo efetivas nos testes in vitro, foram selecionadas para avaliação in vivo. Nos testes in vivo camundongos Balb/c foram tratados oralmente, 45 ou 60 dias após a infecção. No 45° dia de infecção os animais foram tratados com 100 e 200 mg/kg da fração 2 butanólica, 100 mg/kg das lignanas nirantina, filantina + nirantina e filantina + filtetralina + nirtetralina em dose única e 100 mg/kg da fração 2 butanólica distribuídos em 3 dias consecutivos. Já no 60° dia de infecção o tratamento foi feito em dose única com a fração 2 butanólica, nirantina, filantina + nirantina e filantina + filtetralina + nirtetralina (100mg/kg). A atividade in vivo foi avaliada com base nos seguintes parâmetros: ação sobre os vermes adultos, ovos eliminados nas fezes, oograma, formação das reações granulomatosas, e ação sobre o tegumento (feita por microscopia eletrônica de varredura - MEV). Os tratamentos mais efetivos no 45° dia de infecção foram apresentados pelos grupos tratados com filantina + nirantina e nirantina (100mg/kg). A lignana nirantina apresentou taxa de redução do número de ovos de 90,3% e a associação da filantina + nirantina, 63,8%. Os resultados referentes aos demais parâmetros (redução do total de vermes, de vermes fêmeas e do número de granulomas) foram semelhantes, apresentando taxas de redução em torno de 58%. Além dessas alterações, as imagens obtidas por MEV mostraram extensas lesões no tegumento dos vermes machos. No 60° dia de infecção, a associação de lignanas filantina + nirantina e a fração 2 butanólica (100mg/kg) apresentaram as taxas de redução mais significativas: 50,8% e 46,7% para o número total de vermes, 47,2% e 42,7% para o número de vermes fêmeas, 87,5% e 98,3% para o número de ovos e 44% e 18% para o número de granulomas, respectivamente. Assim sendo, de acordo com os parâmetros biológicos avaliados neste trabalho, a associação das lignanas filantina: nirantina na concentração de 100 mg/kg revelou um efeito esquistossomicida promissor, uma vez que foi efetiva nos dois períodos estudados
Abstract: The dissemination of schistosomiasis and the threat of its causing agents becoming resistant to the drug of choice, i.e., praziquantel, have intensified the research with medicinal plants to promote the development of new schistosomicidal drugs. Phyllanthus amarus (stone-breaker) is a plant whose anti-inflammatory and hepatoprotective activities have already been attested, which is the reason why it was chosen for this study, as the main pathology of schistosomiasis is the formation of granulomas (inflammatory process) in the liver. The aim of this work was to carry out a bioguided fractionation of the ethanol extract of P. amarus by means of in vitro and in vivo assays in order to verify the schistosomicidal potential of that plant against S. mansoni, BH strain. To carry out the in vitro assays, the collected adult worms were incubated in plates containing RPMI 1640 medium, a pair of mating worms, and samples of crude ethanol extract, fractions of different polarities or isolated lignans at the concentrations of 200, 100, 50 and 25 ?g/mL. The worms were observed over a period of 72 hours, in which mortality rate, egg laying, mating, and tegumentary changes were evaluated. The best in vitro activity was provided by butanol fraction 2, as it proved lethal for 100% of the worms over 48 hours of observation, and so it was used in the in vivo assays. Butanol fraction 2 is mainly composed of lignans, and some of them (nirantin, filantin: nirantin, and filantin + filtetralin + nirtetralin), albeit not effective in the in vitro assays, were selected for in vivo evaluation. In the in vivo assays, Balb/c mice were treated orally 45 or 60 days following infection. On the 45th day following infection, the animals were treated with 100 and 200 mg/kg of butanol fraction 2, 100 mg/kg of filantina:nirantin and filantin + filtetralin + nirtetralin in a single dose, and 100 mg/kg of butanol fraction 2 distributed over 3 consecutive days. On the 60th day following infection, the treatment was carried out in a single dose with 100 mg/kg of butanol fraction 2, nirantin, filantina:nirantin, and filantin + filtetralin + nirtetralin. The in vivo activity was evaluated based on the following parameters: action on adult worms, eggs eliminated in the stool, egg counting, granulomatous reactions, and action on the tegument of the worms (using scanning electron microscopy (SEM). The most effective treatments on the 45th day were those carried out with 100 mg/kg of filantina:nirantin, and nirantin. The association of filantina:nirantin provided a reduction of 63.8% in the number of eggs, whereas nirantin achieved a reduction rate of 90.3%. The results for the other parameters (reduction in the total number of worms, number of females, and number of granulomas) were similar with reduction rates around 58%. In addition to such changes, images obtained by SEM showed extensive lesions on the tegument of male worms. On the 60th day following infection, the filantin + nirantin association and butanol fraction 2 at 100 mg/kg achieved the most significant xxiii reduction rates: 50.8% and 46.7% in the total number of worms, respectively; 47.2% and 42.7% in the number of females, respectively; 87.5% and 98.3% in the number of eggs, respectively; and 44% and 18% in the number of granulomas, respectively. Therefore, according to the biological parameters evaluated in this work, the association of the lignans filantina:nirantin at 100 mg/kg has a promising schistosomicidal activity, as it was effective over two periods of treatment
Doutorado
Parasitologia
Doutora em Parasitologia
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Frazier, Taylor Price. "A Comprehensive Analysis of Rust Disease Resistance in the Bioenergy Plant Switchgrass (Panicum virgatum L.)." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/78320.
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Switchgrass is a C4 perennial grass that is currently being developed for use as a second generation lignocellulosic biofuel crop. For switchgrass to be fully utilized as a bioenergy crop, large-scale plantings of elite switchgrass germplasm, possibly in monoculture, are likely to occur. This practice may increase the selection pressure on plant pathogens, such as switchgrass rust, which could result in devastating disease epidemics. The identification and deployment of quantitative trait loci (QTLs) and major plant disease resistance genes (R) in switchgrass breeding programs could offer broad spectrum and durable disease resistance in commercial switchgrass cultivars. 'Alamo', a lowland cultivar, is generally resistant to switchgrass rust whereas 'Dacotah', an upland cultivar, is highly susceptible. I hypothesized that major R genes and/or QTLs were contributing to the differences in disease phenotypes of these two cultivars. In this dissertation, bioinformatics and molecular biology approaches were employed to dissect the genetic mechanisms underlying switchgrass rust disease resistance. Novel pseudo-F2 mapping populations were created from a cross derived from 'Alamo' and 'Dacotah'. RNA-sequencing of the pseudo-F2 progenies of 'Alamo' x 'Dacotah' was used to construct a genetic linkage map and to identify potential QTLs correlating with disease resistance. In addition, a homology-based computational method was used to identify 1,011 potential NB-LRR R genes in the switchgrass genome (v 1.1). These potential R genes were characterized for polymorphism and expression differences between 'Alamo' and 'Dacotah'. Moreover, I found that some NB-LRR genes are developmentally regulated in switchgrass. One of the major objectives of switchgrass breeding programs is to develop cultivars with improved feedstock quality; however, changes in the components of the plant cell wall may affect disease resistance. I hypothesized that genetically modified switchgrass plants with altered cell wall components will respond differently than the wild-type to switchgrass rust. Transgenic switchgrass plants overexpressing AtSHN3, a transcription factor with known functions in epicuticular wax accumulation and cell wall deposition, were created. I found that AtSHN3-overexpressing transgenic switchgrass lines were more susceptible than wild-type plants in their response to switchgrass rust. Overall, the results of this dissertation provide a platform for elucidating the molecular mechanisms underlying resistance of switchgrass to switchgrass rust. These findings will help breeders create switchgrass cultivars with improved disease resistance, and will ultimately allow switchgrass to be used for sustainable biomass production.Ph. D.
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Charlet, Stéphane. "Etude des mécanismes de régulation physiologique et biochimique de l'accumulation de lignanes chez le lin : mise en œuvre aux niveaux de la cellule et de la plante entière." Amiens, 2003. http://www.theses.fr/2003AMIED008.
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Le lin (Linum usitatissimum), dont l'intérêt industriel est actuellement lié à ses fibres et son huile, accumule également des molécules d'intérêt thérapeutique : des lignanes, et particulièrement le sécoisolaricirésinol diglucoside (SDG) ainsi que du matairésinol. Ces substances sont des phytoestrogènes, susceptibles de prévenir la survenue de cancers hormono-dépendants. L'étude du métabolisme des lignanes a nécessité dans un premier temps de pouvoir disposer de méthodes analytiques des lignanes du lin, ainsi que de leurs précurseurs. Pour cela les molécules de référence, non disponibles dans le commerce, ont tout d'abord été purifiées pour servir de standards dans les méthodes de dosage. Des protocoles d'analyse chromatographique (HPLC) ont été optimisés. Ce sont en particulier les conditions d'hydrolyse pour libérer les lignanes des complexes auxquels ils sont liés qui ont été définies. Les dérivés du SDG ont alors pu être dosés directement ou indirectement sous forme d'anhydrosécoisolaricirésinol. La mise en œuvre de ces méthodes a permis de montrer que dans la plante les lignanes sont exclusivement présents dans la graine (80% de la teneur totale) et dans le fruit (15%). Dans les différents types de cultures in vitro initiés dans le laboratoire, aucune trace des lignanes de la plante n'a pu être détectée. Par contre un néolignane, purifié et identifié comme un monoglucoside de l'alcool déhydrodiconiférylique (DCG), est accumulé en forte concentration. Il a été montré que la teneur en DCG est influencée par la balance hormonale dans les milieux de culture, ainsi que par la photopériode. Des cellules cultivées en présence de BAP (0. 5mg. L-1), et à l'obscurité accumulent la plus forte quantité de DCG (74mg. G-1 M. S. ). Une supplémentation des cultures en phénylalanine marquée au 13C, n'a pas permis de retrouver le marquage dans d'autres précurseurs du DCG. L'interaction des cellules avec une matrice d'alginate, dans laquelle elles sont immobilisées, induit la sécrétion de DCG dans le milieu sans toutefois modifier le taux gobal d'accumulationFlaxseed (Linum usitatissimum) fibres and oil are valuable products for industrial applications. However this plant also accumulates lignans phytoestrogens : secoisolariciresinol diglucoside (SDG) and matairesinol. These compounds have been proved to prevent the outcome of some hormone-dependent cancers. The study of their metabolism requires the use of efficient analytical methods to evaluate them as well as their biosynthetic precursors. In a first part of our work, lignans have been purified from flaxseeds, for a further use as standards in the analytical protocols. HPLC methods were optimised , mainly at the keypoint of the release of lignans from the complexes in which they are bound in the plant. It was then possible to evaluate secoisolariciresinol derivatives, either directly or indirectly as anhydrosecoisolariciresinol, a conversion form of flaxseed lignans. The application of these analytical tools allowed to reveal that in the plant, lignans were exclusively accumulated in the seeds (80% of total) and the fruits (15%). No trace of the flaxseed lignans could be detected in various in vitro cultures. However the dehydrodiconiferyl alcohol monoglucoside (DCG), a neolignan was purified and identified from these cultures in which it is accumulated at a very high level. It was shown that plant growth regulators as well as photoperiod deeply influence the lignan levels of the cultures. The highest values (74mg. G-1 DW) were reached when of BAP (0. 5mg. L-1) was added to the culture medium, and when the cultures were maintained in the dark. A 13C labelled phenylalanine supplementation in the cultures did not allow the identification of other labelled lignan precursors. Moreover, the interaction of the plant cells with an alginate matrix in which they were immobilised induced lignans release in the culture medium without modifying their total amount
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Agarwal, Tina R. "Syntelogs of MYB31 and MYB42 Exhibit Divergent Roles in Phenylpropanoid Pathway Regulation in Maize, Sorghum, and Rice." University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1452181737.
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Berthet, Serge. "Identification et caractérisation de laccases impliquées dans la polymérisation des monolignols chez la plante modèle Arabidopsis thaliana." Paris 11, 2010. http://www.theses.fr/2010PA112257.
Full textAbstract:
Alors qu'il est établi que les peroxydases sont impliquées dans la polymérisation des précurseurs de lignine, le rôle des laccases (EC 1. 10. 3. 2) dans la lignification constitutive reste énigmatique. Nous avons étudié des mutants d'insertion de l'ADN-T d'Arabidopsis thaliana. Dans un premier temps, deux gènes (AtLAC4 et AtLAC17) fortement exprimés dans les tiges ont été identifiés. AtLAC17 s'exprime spécifiquement dans les fibres interfasciculaires et AtLAC4 s'exprime dans les vaisseaux et les fibres interfasciculaires. Nous avons produit deux doubles mutants, kim et snips, par croisement des mutants pour les gènes AtLAC17 (lac17) et AtLAC4 (irx12 et lac4g). Les simples et doubles mutants présentent une croissance normale, à l'exception de snips qui est parfois semi-nain et possèdent des vaisseaux collapsés. Si les simples mutants présentent une diminution modérée de leur teneur en lignine, les tiges de kim (irx12 x lac17) et snips (lac4g x lac17) ont un contenu réduit de 20% et 40% respectivement. Cette diminution de teneur en lignine conduit à un meilleur rendement de saccharification. Des thioacidolyses révèlent que l'absence d'activité AtLAC17 se répercute principalement sur le dépôt des unités G dans les fibres interfasciculaires et la complémentation du mutant lac17 avec la séquence de AtLAC17 restaure un profil de lignification normal. Cette étude met en évidence que AtLAC4 et AtLAC17 sont toutes deux impliquées dans la lignification constitutive des tiges d'Arabidopsis et que l'absence de AtLAC17 a un impact sur la polymérisation des unités G spécifiquement au niveau des fibres, suggérant un rôle dans les étapes précoces de la lignificationWhile it is established that peroxidases are involved in the polymerization of lignin precursors, it is not yet clear whether laccases (EC 1. 10. 3. 2) participate to constitutive lignification. Ln order to address this issue, we studied laccase T-DNA insertion mutants in Arabidopsis thaliana. We first identified two genes, AtLAC4 and AtLAC17, highly expressed in stems. AtLAC17was specifically expressed in the interfascicular fibers while AtLAC4 was expressed in vascular bundles and interfascicular fibers. We produced two double mutants, kim and snips, by crossing the AtLAC17 (lac17) mutant with two AtLAC4 mutants (named irx12 and lac4g). The single and double mutants displayed normal growth, except snips, which sometimes had a semi-dwarf phenotype and collapsed vessels. While the single mutants had moderately reduced lignin levels, the stems of kim (irx12 x lac17) and snips (lac4g x lac17) displayed lignin content reduced by 20% and 40%, respectively. This lower lignin level improved their saccharification yield. Thioacidolysis revealed that disrupting AtLAC17 mainly affected the deposition of G lignin units in the interfascicular fibers and that complementation of lac17 with AtLAC17 restored the normal lignin profile. This study provides evidence that both AtLAC4 and AtLAC17 contribute to the constitutive lignification of Arabidopsis stems and that AtLAC17 is involved in the deposition of G lignin units in fibers, a specificity, which suggests a role at the early lignification stage
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Kärkönen, Anna. "Plant tissue cultures as models for tree physiology : somatic embryogenesis of Tilia cordata and lignin biosynthesis in Picea abies suspension cultures as case studies." Helsinki : University of Helsinki, 2002. http://ethesis.helsinki.fi/julkaisut/mat/bioti/vk/karkonen/.
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