肠道菌群缺失在紫杉醇诱导的神经病理性疼痛中的作用

探索肠道菌群缺失对紫杉醇诱导的神经病理性疼痛行为的影响及相关机制。

32只C57雄性小鼠随机分为4组（n=8）：对照组（Control组）、抗生素组（ASC组）、紫杉醇组（PTX组）和抗生素+紫杉醇组（PTX+ASC组）。紫杉醇造模前,抗生素组小鼠口服ASC三联广谱抗生素（1 mg/mL）,持续2周。第1、3、5、7天腹腔注射紫杉醇（2 mg/kg）建立神经病理性疼痛模型。紫杉醇给药前和给药后第14天分别测定小鼠的热缩足潜伏期（TWL）和机械缩足反应阈（MWT）。行为学实验结束后,取小鼠粪便样本（5～6粒/只）用于16S rRNA扩增子测序分析。Western blot法检测小鼠脊髓水平Toll样受体4（TLR4）蛋白和核因子κB（NF-κB）蛋白的表达情况。免疫荧光检测脊髓星形胶质细胞的活化情况。ELISA实验检测脊髓内肿瘤坏死因子α（TNF-α）和白细胞介素−1β（IL-1β）的表达水平。

与对照组相比,口服ASC抗生素的小鼠,肠道菌群在科水平上Muribaculaceae、乳杆菌科和阿克曼菌科相对丰度显著下降（P＜0.05）;紫杉醇2 mg/kg造模后,小鼠机械/热痛阈值显著下降（P＜0.05）,小鼠脊髓TLR4和NF-κB蛋白和促炎性因子TNF-α、IL-1β表达水平显著升高（P＜0.05）,脊髓星形胶质细胞异常活化（P＜0.05）。与紫杉醇组相比,抗生素+紫杉醇组小鼠的机械/热痛阈值显著升高（P＜0.05）。小鼠脊髓内TLR4和NF-κB蛋白和TNF-α、IL-1β的表达显著降低（P＜0.05）,星形胶质细胞活化水平显著减弱（P＜0.05）。

ASC抗生素三联给药造成的肠道菌群缺失可缓解紫杉醇诱导的小鼠神经病理性疼痛,并可抑制紫杉醇诱导的脊髓TLR4/NF-κB信号通路蛋白的过表达,星形胶质细胞活化和炎性反应。

     

Reciprocal Signaling between the Ectoderm and a Mesendodermal Left-Right Organizer Directs Left-Right Determination in the Sea Urchin Embryo

During echinoderm development, expression of nodal on the right side plays a crucial role in positioning of the rudiment on the left side, but the mechanisms that restrict nodal expression to the right side are not known. Here we show that establishment of left-right asymmetry in the sea urchin embryo relies on reciprocal signaling between the ectoderm and a left-right organizer located in the endomesoderm. FGF/ERK and BMP2/4 signaling are required to initiate nodal expression in this organizer, while Delta/Notch signaling is required to suppress formation of this organizer on the left side of the archenteron. Furthermore, we report that the H⁺/K⁺-ATPase is critically required in the Notch signaling pathway upstream of the S3 cleavage of Notch. Our results identify several novel players and key early steps responsible for initiation, restriction, and propagation of left-right asymmetry during embryogenesis of a non-chordate deuterostome and uncover a functional link between the H⁺/K⁺-ATPase and the Notch signaling pathway.     

Arbuscular mycorrhizal symbiosis can counterbalance the negative influence of the exotic tree species Eucalyptus camaldulensis on the structure and functioning of soil microbial communities in a sahelian soil

The hypothesis of the present study was that bacterial communities would differentiate under Eucalyptus camaldulensis and that an enhancement of arbuscular mycorrhizal (AM) density would minimize this exotic plant species effect. Treatments consisted of control plants, preplanting fertilizer application and AM inoculation. After 4 months of culture in autoclaved soil, E. camaldulensis seedlings were either harvested for growth measurement or transferred into containers filled with the same soil but not sterilized. Other containers were kept without E. camaldulensis seedlings. After 12 months, effects of fertilizer amendment and AM inoculation were measured on the growth of Eucalyptus seedlings and on soil microbial communities. The results clearly show that this plant species significantly modified the soil bacterial community. Both community structure (assessed by denaturing gradient gel electrophoresis profiles) and function (assessed by substrate-induced respiration responses including soil catabolic evenness) were significantly affected. Such changes in the bacterial structure and function were accompanied by disturbances in the composition of the herbaceous plant species layer. These results highlight the role of AM symbiosis in the processes involved in soil bio-functioning and plant coexistence and in afforestation programmes with exotic tree species that target preservation of native plant diversity.     

基于ISSR标记的辽宁4个东北林蛙种群遗传多样性分析

辽宁是东北林蛙Rana dybowskii主要分布地之一,种群数量巨大,其群体遗传多样性有待评估.本研究应用ISSR标记技术对东北林蛙4个种群105个样本进行研究,5个引物共获得44条清晰谱带,4个种群的多态位点率均大于75%,Nei's基因多样性为0.2851,Shannon信息指数为0.4476,显示了较高的遗传多样性.对遗传分化系数、Nei's遗传距离、AMOVA分子变异巢式方差分析和F-统计量等遗传参数的统计结果表明,辽宁东北林蛙种群间已经出现一定程度的遗传分化,分析认为,自然屏障(高山和平原等)以及栖息地片段化是其遗传分化形成的主要因素.     

Molecular Diversity of New Thermococcales Isolates from a Single Area of Hydrothermal Deep-Sea Vents as Revealed by Randomly Amplified Polymorphic DNA Fingerprinting and 16S rRNA Gene Sequence Analysis

Members of the Thermococcales are anaerobic Archaea belonging to the kingdom Euryarchaea that are studied in many laboratories as model organisms for hyperthermophiles. We describe here a molecular analysis of 86 new Thermococcales isolates collected from six different chimneys of a single hydrothermal field located in the 13°N 104°W segment of the East Pacific ridge at a depth of 2,330 m. These isolates were sorted by randomly amplified polymorphic DNA (RAPD) fingerprinting into nine groups, and nine unique RAPD profiles were obtained. One RAPD group corresponds to new isolates of Thermococcus hydrothermalis, whereas all other groups and isolates with unique profiles are different from the 22 reference strains included in this study. Analysis of 16S rRNA gene sequences of representatives of each RAPD group and unique profiles showed that one group corresponds to Pyrococcus strains, whereas all the other isolates are Thermococcus strains. We estimated that our collection may contain at least 11 new species. These putative species, isolated from a single area of hydrothermal deep-sea vents, are dispersed in the 16S rRNA tree among the reference strains previously isolated from diverse hot environments (terrestrial, shallow water, hydrothermal vents) located around the world, suggesting that there is a high degree of dispersal of Thermococcales. About one-half of our isolates contain extrachromosomal elements that could be used to search for novel replication proteins and to develop genetic tools for hyperthermophiles.     

Haemosporidian Parasites of Antelopes and Other Vertebrates from Gabon,Central Africa

Re-examination, using molecular tools, of the diversity of haemosporidian parasites (among which the agents of human malaria are the best known) has generally led to rearrangements of traditional classifications. In this study, we explored the diversity of haemosporidian parasites infecting vertebrate species (particularly mammals, birds and reptiles) living in the forests of Gabon (Central Africa), by analyzing a collection of 492 bushmeat samples. We found that samples from five mammalian species (four duiker and one pangolin species), one bird and one turtle species were infected by haemosporidian parasites. In duikers (from which most of the infected specimens were obtained), we demonstrated the existence of at least two distinct parasite lineages related to Polychromophilus species (i.e., bat haemosporidian parasites) and to sauropsid Plasmodium (from birds and lizards). Molecular screening of sylvatic mosquitoes captured during a longitudinal survey revealed the presence of these haemosporidian parasite lineages also in several Anopheles species, suggesting a potential role in their transmission. Our results show that, differently from what was previously thought, several independent clades of haemosporidian parasites (family Plasmodiidae) infect mammals and are transmitted by anopheline mosquitoes.     

The effect of the soil-feeding termite Cubitermes niokoloensis on soil microbial activity in a semi-arid savanna in West Africa

Plant and Soil - Soil-feeding termite mounds are an important, highly specific soil microbial compartment in semi-arid savannas. The aim of this study was to determine the role of these mounds in...