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。

     

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.     

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.     

Restriction fragment length polymorphism (RFLP) analysis of bovine nuclear protein genes

Summary We have recently cloned both the bovine protamine (Krawetz et al. 1987, DNA 6: 47–57) and high mobility group (HMG-1) cDNAs (Pentecost and Dixon 1984, Bioscience Reports 4: 49–57). They have been used as probes for Restriction Fragment Length Polymorphism analysis of male-female pairs of different species and breeds, within the genus Bos. Utilizing this approach we have studied inheritance, chromosomal location and gene copy number of the bovine protamine and HMG-1 genes. This revealed that these nuclear protein genes are highly conserved suggesting that selective pressure has maintained their gene structures during evolution. A polymorphic Taq 1 restriction fragment was identified that was shown to be a heritable marker. These genes are not sex-linked and are present in a single copy for protamine and at least two copies for the HMG-1.     

Natively oxidized amino acid residues in the spinach cytochrome <Emphasis Type="Italic">b</Emphasis><Subscript><Emphasis Type="Italic">6</Emphasis></Subscript><Emphasis Type="Italic">f</Emphasis> complex

The cytochrome b ₆ f complex of oxygenic photosynthesis produces substantial levels of reactive oxygen species (ROS). It has been observed that the ROS production rate by b ₆ f is 10–20 fold higher than that observed for the analogous respiratory cytochrome bc₁ complex. The types of ROS produced (O₂^{??, 1}O₂, and, possibly, H₂O₂) and the site(s) of ROS production within the b ₆ f complex have been the subject of some debate. Proposed sources of ROS have included the heme b _p , PQ _p ^?? (possible sources for O₂^??), the Rieske iron–sulfur cluster (possible source of O₂^?? and/or ¹O₂), Chl a (possible source of ¹O₂), and heme c _n (possible source of O₂^?? and/or H₂O₂). Our working hypothesis is that amino acid residues proximal to the ROS production sites will be more susceptible to oxidative modification than distant residues. In the current study, we have identified natively oxidized amino acid residues in the subunits of the spinach cytochrome b ₆ f complex. The oxidized residues were identified by tandem mass spectrometry using the MassMatrix Program. Our results indicate that numerous residues, principally localized near p-side cofactors and Chl a, were oxidatively modified. We hypothesize that these sites are sources for ROS generation in the spinach cytochrome b ₆ f complex.     

Coastal eutrophication assessment in the United States

Recent national assessments document that nitrogen-driven coastal eutrophication is widespread and increasing in the United States. This significant coastal pollution problem includes impacts including increased areas and severity of hypoxic and anoxic waters; alteration of food webs; degradation and loss of sea grass beds, kelp beds and coral reefs; loss of biodiversity; and increased incidences and duration of harmful algal blooms. In this paper, we review two complementary approaches to assessing the causes and consequences of these trends, as well as potential remedies for them. The first is a national-scale assessment, drawn primarily from expert knowledge of those most familiar with the individual estuaries and integrated into a common analysis framework. The second approach, focused on the Mississippi/Atchafalaya basin – the largest US drainage basin – draws upon both quantitative and qualitative analyses within a comprehensive framework, Integrated Assessment.