Analyse des relations entre plasticité architecturale des buissons et prolifération de leurs populations

Réalisé en cotutelle avec l'Université Montpellier II

Anthelmintic effect of plant extracts containing condensed and hydrolyzable tannins on Caenorhabditis elegans, and their antioxidant capacity

Although tannin-rich forages are known to increase protein uptake and to reduce gastrointestinal nematode infections in grazing ruminants, most published research involves forages with condensed tannins (CT), while published literature lacks information on the anthelmintic capacity, nutritional benefits, and antioxidant capacity of alternative forages containing hydrolyzable tannins (HT). We evaluated the anthelmintic activity and the antioxidant capacity of plant extracts containing either mostly CT, mostly HT, or both CT and HT. Extracts were prepared with 70% acetone, lyophilized, redissolved to doses ranging from 1.0mg/mL to 25mg/mL, and tested against adult Caenorhabditis elegans as a test model. The extract concentrations that killed 50% (LC50) or 90% (LC90) of the nematodes in 24h were determined and compared to the veterinary anthelmintic levamisole (8mg/mL). Extracts were quantified for CT by the acid butanol assay, for HT (based on gallic acid and ellagic acid) by high-performance liquid chromatography (HPLC) and total phenolics, and for their antioxidant activity by the oxygen radical absorbance capacity (ORAC) assay. Extracts with mostly CT were Lespedeza cuneata, Salix X sepulcralis, and Robinia pseudoacacia. Extracts rich in HT were Acer rubrum, Rosa multiflora, and Quercus alba, while Rhus typhina had both HT and CT. The extracts with the lowest LC50 and LC90 concentrations, respectively, in the C. elegans assay were Q. alba (0.75 and 1.06mg/mL), R. typhina collected in 2007 (0.65 and 2.74mg/mL), A. rubrum (1.03 and 5.54mg/mL), and R. multiflora (2.14 and 8.70mg/mL). At the doses of 20 and 25mg/mL, HT-rich, or both CT- and HT-rich, extracts were significantly more lethal to adult C. elegans than extracts containing only CT. All extracts were high in antioxidant capacity, with ORAC values ranging from 1800μmoles to 4651μmoles of trolox equivalents/g, but ORAC did not correlate with anthelmintic activity. The total phenolics test had a positive and highly significant (r=0.826, p≤0.01) correlation with total hydrolyzable tannins. Plants used in this research are naturalized to the Appalachian edaphoclimatic conditions, but occur in temperate climate areas worldwide. They represent a rich, renewable, and unexplored source of tannins and antioxidants for grazing ruminants, whereas conventional CT-rich forages, such as L. cuneata, may be hard to establish and adapt to areas with temperate climate. Due to their high in vitro anthelmintic activity, antioxidant capacity, and their adaptability to non-arable lands, Q. alba, R. typhina, A. rubrum, and R. multiflora have a high potential to improve the health of grazing animals and must have their anthelmintic effects confirmed in vivo in both sheep and goats. © 2012.

Anti-HIV-1 activities of extracts from the medicinal plant Rhus chinensis

Rhus chinensis, a species used in folk medicine by Chinese native people, the anti-HIV-1 activities of the petroleum ether, ethyl acetate, butanol and aqueous extract of Rhus chinensis, named as RC-1, RC-2, RC-3 and RC-4, respectively, was evaluated. The

Anti-HIV-1 activities of compounds isolated from the medicinal plant Rhus chinensis

Aim of the study: Previously, we reported that the petroleum ether fraction, RC-1, and EtOAc fraction, RC-2, of the medicinal plant Rhus chinensis showed potent anti-HIV-1 activities. To address anti-HIV-1 constituents of RC-1 and RC-2, 17 compounds were

Purification and characterization of hydrosoluble components from the sap of Chinese lacquer tree Rhus vernicifera

Continuous gradient elution chromatography (CGEC) was employed to purify and separate enzymes and polysaccharides from the sap of Rhus vernicifera Chinese lacquer tree. There are three different molecules with laccase enzyme activity. Two are enzymes of each other (L1, and L2), whereas the third (RL) is an entirely separate entity. Two polysaccharides (GP1 and GP2) were also found. The Rhus laccase (RL), and isoenzymes L1 and L2, have peak molecular masses of 109,100, 120,000, 103,000 respectively; each has four copper atoms per molecule, and the pI values were 8.2, 8.6, and 9.1, respectively. The structure of the laccases was studied by Fourier-transform infrared (FT-IR) and Matrix-assisted laser desorption/ionization time-of flight (MALDI-TOF) mass spectrometry. The typical amide I (1646 cm(-1)) and amide II (1545 cm(-1)) bands were observed. The results from MALDI-TOF were similar to those from CGEC, but the molecular mass from the MALDI-TOF was significantly different from that obtained from sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). (c) 2006 Elsevier B.V. All rights reserved.

Czynniki glebowe w infekcji trawy mannicy odstającej (Puccinellia distans) endofitycznym grzybem Epichloё typhina: określenie ich roli z zastosowaniem analiz przestrzennych

Wydział Biologii

Vers une gestion démocratique du risque environnemental Le système participatif de la convention d'Århus: faiblesses et potentialités

Les évolutions scientifiques et technologiques engendrent des risques environnementaux complexes. Ces risques doivent être gérés démocratiquement, dans l’intérêt du dêmos. Dans la démocratie représentative, les autorités publiques recourent souvent à l’expertise scientifique pour éclairer leurs décisions relatives à ces risques. Or, ces experts ne le sont pas dans d’autres aspects tout aussi importants tels que les considérations éthiques et les perceptions des risques par le dêmos. En principe, les autorités publiques intègreraient ces autres aspects dans leurs décisions relatives aux risques environnementaux : sur la base d’une évaluation scientifique d’un risque déterminé, les représentants en assureraient une gestion démocratique. Autrement formulé, les autorités publiques garantiraient un filtre démocratique entre l’évaluation scientifique d’un risque environnemental et la décision publique relative à ce risque. Or, sous l’influence exclusive des experts scientifiques et éloignée du dêmos, elles ne sont pas aptes à garantir ce filtre. Les décisions publiques relatives aux risques environnementaux se calquent principalement sur l’évaluation scientifique de ceux-ci. Afin de pallier ces écueils l’idée de faire participer directement le dêmos à l’élaboration de la décision publique environnementale est née. Cette participation enrichirait et nuancerait l’expertise scientifique et permettrait aux autorités publiques d’intégrer dans leurs décisions d’autres facettes des risques environnementaux que les facettes purement scientifiques. Le filtre démocratique entre l’évaluation scientifique et la décision publique serait rétabli. D’abord organisée, en droit international, dans le cadre de l’évaluation des incidences sur l’environnement d’activités susceptibles d’y avoir un impact significatif, la participation directe du public au processus décisionnel a ensuite été étendue. Cela a été tout particulièrement illustré par la convention d’Århus du 25 juin. L’intervention examinera si et comment le système participatif de la convention d’Århus assure réellement une gestion démocratique du risque environnemental et pointera de sérieuses faiblesses démocratiques du système. Explorant les potentialités du système participatif de la convention d’Århus, l’intervention offrira des suggestions pour remédier à ses faiblesses, afin d’assurer une gestion véritablement démocratique du risque environnemental.

Fungal Planet description sheets: 128-153

Novel species of microfungi described in the present study include the following from Australia: Catenulostroma corymbiae from Corymbia, Devriesia stirlingiae from Stirlingia, Penidiella carpentariae from Carpentaria, Phaeococcomyces eucalypti from Eucalyptus, Phialophora livistonae from Livistona, Phyllosticta aristolochiicola from Aristolochia, Clitopilus austroprunulus on sclerophyll forest litter of Eucalyptus regnans and Toxicocladosporium posoqueriae from Posoqueria. Several species are also described from South Africa, namely: Ceramothyrium podocarpi from Podocarpus, Cercospora chrysanthemoides from Chrysanthemoides, Devriesia shakazului from Aloe, Penidiella drakensbergensis from Protea, Strelitziana cliviae from Clivia and Zasmidium syzygii from Syzygium. Other species include Bipolaris microstegii from Microstegium and Synchaetomella acerina from Acer (USA), Brunneiapiospora austropalmicola from Rhopalostylis (New Zealand), Calonectria pentaseptata from Eucalyptus and Macadamia (Vietnam), Ceramothyrium melastoma from Melastoma (Indonesia), Collembolispora aristata from stream foam (Czech Republic), Devriesia imbrexigena from glazed decorative tiles (Portugal), Microcyclospora rhoicola from Rhus (Canada), Seiridium phylicae from Phylica (Tristan de Cunha, Inaccessible Island), Passalora lobeliaefistulosis from Lobelia (Brazil) and Zymoseptoria verkleyi from Poa (The Netherlands). Valsalnicola represents a new ascomycete genus from Alnus (Austria) and Parapenidiella a new hyphomycete genus from Eucalyptus (Australia). Morphological and culture characteristics along with ITS DNA barcodes are also provided. © 2012 Nationaal Herbarium Nederland & Centraalbureau voor Schimmelcultures.

Assessment Method for Leaf Litters Allelopathic Effect on Cyanobacteria

A new bioassay technique combining leaf disk and softagar over-layer methods was developed to investigate the allelopathic effect of deciduous leaf litters on the growth of cyanobacteria ( Microcystis aeruginosa Kütz.). Bioactive substances exuded from leaf disks caused inhibitory plaques on the agar plate containing cyanobacteria , and the rate of diffusion depended on the specific leaf disk area. Most of the leaf litters collected around reservoirs in Japan showed inhibitory activity to M. aeruginosa , with Rhus trichocarpa Miq., Quercus variabilis Blume and Mallotus japonicus (Thunb.) Muell. Arg. being the strongest among the 22 tested species.(PDF has 4 pages.)

Cloning and analysis of laccases from acinetobacter baumannii isolates

Laccases (benzenediol : oxygen oxi doreductases; EC 1.10.3.2) are wide spread i n nature. They are usually found in higher plants and fungi (Thurston 19 94; Mayer and Staples 2002), but recently some bacterial laccases have also been found . The first laccase studied was from Rhus vernicifera in 1883, a Japanese lacquer tree, fr om which the name laccase was derived (Yoshida , 1883). These enzymes belong to the group of bl ue multi - copper oxidases (MCOs) . They usually contain four copper atoms located in three distinct sites. Each site reacts differently to light. The Type 1 (T1) site copper atom absorbs intensely at 600 nm and emits the blue light , the Type 2 (T2) site copper atom is not visible in the absorption spectr um and last, the Type 3 (T3) site has two c opper atoms and absorbs at 330 nm ( Santhanam et al . , 2011; Quintanar et al . , 2007 ) . The protei n structure acts as a complex ligand for the catalytic coppers, providing them the right structure where changes between the reduction states are thermodynamically possible (Dub é , 2008 ) . These enzymes oxidize a surprisingly wide variety of organic and inorganic compounds like, diphenols, polyphenols, substituted phenols, diamines and a romatic amines, with concomitant reduction of molecular oxygen to water (Thurston , 1

西夫韦肽和盐肤木提取物体外抗HIV 活性及机制研究

本论文主要由3 个相对独立的部分组成: 西夫韦肽抗HIV 活性机制研究及其 联合用药和耐药性研究，盐肤木提取物及其化合物抗HIV 活性机制研究和精子 顶体反应抑制剂AGB 抗HIV 活性及机制研究。 HIV 侵入抑制剂是抗HIV 药物研发的热点。该类抑制剂靶定在病毒复制周 期早期，为HARRT 疗法提供了更多新的药物组合，且该类抑制剂对临床中已产 生的耐药毒株也有较好的抑制作用。目前FDA 批准上市的侵入抑制剂仅有T-20， 急需开发新一类的HIV-1 侵入抑制剂。西夫韦肽是由36 个氨基酸组成的多肽， 我们对西夫韦肽进行了一系列体外抗HIV 药效学的实验来研究西夫韦肽体外抗 HIV 活性以及作用机制。实验结果表明西夫韦肽对多种HIV 宿主细胞毒性小， 可以有效抑制HIV-1IIIB 诱导的C8166 细胞的病变效应，EC50 值仅为7.8ng/ml ， TI 值大于 384,615;在不同的检测方法中，西夫韦肽均表现出了比T-20 更好的抑 制活性，EC50 值低了13-42 倍。在对HIV-1 临床分离株、耐药株、两株HIV-2 毒株和SIVmac239 的抑制活性研究表明西夫韦肽也可以很好地抑制 HIV-1 临床株 HIV-1KM018 的复制，EC50 值低至4.4ng/ml，对耐药株HIV-174V、HIV-2 和 SIVmac239 的复制也均有较好的抑制作用。 在机制研究中，我们发现西夫韦肽极有效地抑制HIV-1慢性感染H9细胞与 正常C8166细胞间的融合作用，EC50 低至0.4ng/ml，表明西夫韦肽可以以极低的 浓度有效抑制HIV进入宿主细胞。用GST-pull down 实验进一步验证了西夫韦肽 和T-20可以很好地与HR1结合而不能与HR2结合，作用机制就是特异地与gp41的 HR1结合从而抑制了6-Helix的形成，阻断了HIV的融合过程。由于HIV的高变异 性，单一药物治疗容易产生耐药性，最终导致治疗失败。因此在新药开发中进行 药物与作用靶不同的已上市药物体外联合用药和耐药性研究是非常必要的，将对 临床应用有指导意义，我们的实验结果表明西夫韦肽与AZT联合用药体外抗HIV-1作用较单独用药好，不同检测方法联合用药比单独使用西夫韦肽的效果好 8.3-9.4倍；耐药性研究表明其体外诱导耐药性产生的时间与T-20相仿，与T-20有 交叉耐药。 我国传统的中医药是个巨大的宝库，有丰富的临床经验，中医药治疗艾滋病 有着一定的潜力。从我国国情出发，利用中医药的独特性及经济性，开发传统的 具有我国特色的艾滋病治疗天然药物成为AIDS 防治工作的当务之急。盐肤木是 中国的本土植物，在我国民间用作传统医药有着悠久的历史。盐肤木茎提取物尤 其是石油醚提取部分RC-1 具有较好的抗HIV 活性，且作用于病毒复制周期的后 期，从中分离得到的化合物1、2、4、5 和6 都是RC-1 的活性成份；盐肤木茎 提取物乙酸乙酯提取物RC-2 中也有较好的抗HIV 作用，其中的化合物8、9、 10 和13 是抗HIV 的活性成分，且作用机制各不相同，这些有效化合物的抗HIV 机制值得进一步的研究。 杀微生物剂是一种局部用药于阴道或宫颈的药物制剂，由女性自主控制防止 性传播疾病病原体包括HIV 的感染，是近年来的研究热点之一。AGB(4`-乙酰胺 苯基 4-胍基苯甲酸酯)是顶体酶的抑制剂，我们的实验表明AGB 有很好的杀精 子作用，还具有体外抗HIV-1 的作用，作用机制主要是阻断HIV-1 进入细胞。

生态恢复后的千烟洲植物群落种类组成及结构特征

Qianyanzhou(QYZ) Ecological Station established in 1983 with an area of 204 hm~2 is affiliated to the Chinese Ecosystem Research Network.Before 1982,herbs had been dominant,sparsely dotted with shrubs.After 20-year restoration of the vegetation,the vegetation showed significant changes in both forest coverage and species diversity.Forest coverage had increased to 93.3% in 1999 from 0.4% in 1982.The vegetation could be broadly classified into two groups: artificial forest,accounting for the most percent,and natural secondary forest.These two groups could be subdivided into 12 types.Based on the 2003 field work,The authors studied plant community composition and vertical structure.The results were as follows: 1) On the study plots were there about 150 species,of which 100,49,and 47 grew in arbor layer and shrub layer and herb layer,respectively.Of 12 community types,the amount of species in shrub layer was larger than that of other two layers.As to the species richness in the different community types,Liquidambar formosana community showed the highest and Imperata cylindrical var.major community the least.The amount of species in arbor layer of artificial forest was smaller than those of natural Pinus massoniana forest,but no difference in understory.2) Loropetalum chinense,Quercus fabric and Vaccinium bracteatum were dominant shrub species with a wide distribution.Three ferns Woodwardia japonica、Dryopteris atrata and Dicrannepteris dichotoma were dominant herb species.Lianas were sparse,but Milletlia reticulata were found in all forest types.3) Up to now some natural regeneration species,such as Eurya muricata、Quercus fabri、Vaccinium bracteatum、Rhus chinensis、Adinandra bockiana,had grown in the arbor layer of artificial forests.Some herb species,such as Arundinella setosa、Miscanthus floridulus、Isachne globosa、Scirpus triqueter,which were dominant ones in the herb layer before the restoration of vegetation,disappeared now.4) The vertical structure of natural Pinus massoniana community and Liquidambar formosana community showed more complex comparing with artificial forests.For the artificial forests,the conifer and broad-leaves mixed forest had a more complex structure.In both natural Pinus(massoniana) community and Liquidambar formosana community,it was dominated by individuals with height of 3～4 m,while 10～12 m in the artificial forests.

Intake, digestibility, and passage of a commercially designed diet by two Propithecus species.

The digestibility and passage of an experimental diet was used to compare the digestive physiology of two Propithecus species: P. verreauxi and P. tattersalli. Though both animals have a similar feeding ecology, the captive status of P. verreauxi is considered more stable than that of P. tattersalli. The test diet included a local tree species, Rhus copallina, at 15% of dry matter intake (DMI) and Mazuri Leafeater Primate Diet at 85% of DMI. The chemical composition of the diet (dry matter basis) was 25% crude protein, 34% neutral detergent fiber (NDF), and 22% acid detergent fiber (ADF) with a gross energy of 4.52 kcal/g. After a 6 week acclimation to the experimental diet, animals were placed in research caging. After a 7 day adjustment period, animals were dosed with chromium mordant and Co-EDTA as markers for digesta passage and all feed refusals and feces were collected at timed intervals for 7 days. Digestibility values, similar for both species, were approximately 65% for dry matter, crude protein, and energy, and 40% and 35% respectively, for NDF and ADF. Transit times (17-18.5 hr) and mean retention times (31-34 hr) were not significantly different between species, and there was no difference between the chromium mordant and Co-EDTA. Serum values for glucose, urea, and non-esterified fatty acids (NEFA) were obtained during four different time periods to monitor nutritional status. While there was no change in serum glucose, serum urea increased over time. The NEFAs increased across all four time periods for P. verreauxi and increased for the first three periods then decreased in the last period for P. tattersalli. Results obtained indicate no difference in digestibility nor digesta passage between species, and that both Propithecus species were similar to other post-gastric folivores.