Cholesterol modulates function of connexin 43 gap junction channel via PKC pathway in H9c2 cells

It has been shown that cholesterol modulates activity of protein kinase C (PKC), and PKC phosphorylates connexin 43 (Cx43) to regulate its function, respectively. However, it is not known whether cholesterol modulates function of Cx43 through regulating activity of PKC. In the present study, we demonstrated that cholesterol enrichment reduced the dye transfer ability of Cx43 in cultured H9c2 cells. Western blot analysis indicated that cholesterol enrichment enhanced the phosphorylated state of Cx43. Immunofluorescent images showed that cholesterol enrichment made the Cx43 distribution from condensed to diffused manner in the interface between the cells. In cholesterol enriched cells, PKC antagonists partially restored the dye transfer ability among the cells, downregulated the phosphorylation of Cx43 and redistributed Cx43 from the diffused manner to the condensed manner in the cell interface. In addition, reduction of cholesterol level suppressed PKC activity to phosphorylate Cx43 and restored Cx43 function in PKC agonist-treated cells. Furthermore, we demonstrated that cholesterol enrichment upregulated the phosphorylated state of Cx43 at Ser368, while PKC antagonists reversed the effect. Taken together, cholesterol level in the cells plays important roles in regulating Cx43 function through activation of the PKC signaling pathway.     

Production of biologically active recombinant annexin B1 with enhanced stability via a tagging system

Annexin B1 is a novel Ca²⁺-dependent phospholipid-binding protein from metacestodes of Taenia solium and has been shown to have many potential biomedical applications. Although annexin B1 has been produced successfully in Escherichia coli, the purified protein has poor stability at room temperature, which has hindered our attempts to further study its structure–function relationship. To increase the stability of the protein, the construction and purification procedures were examined and changed to hopefully increase its effectiveness. In this study, we describe a new recombinant annexin B1 expressed with a hexahistidine tag fused to its N-terminal end, which was purified to homogeneity in two steps using immobilized metal affinity followed by size exclusion chromatography. The final yield was approximately 23 mg/L of bacterial culture. Isoelectric focusing and mass spectrometry analysis showed that the protein purified by this method was quite stable at room temperature, even greater than 3 days later. A series of functional tests indicated that the recombinant protein had high anticoagulant activity, and fluorescence-labeled annexin B1 could bind to the outer membranes of apoptotic mammalian cells and efficiently detect them in the early stages of apoptosis.     

应用于中华鲟的Pop-up标志固定方法

简要介绍了应用于中华鲟(Acipenser sinensis)的pop-up标志固定方法,包括预埋体的制作、植入及pop-up标志悬挂等技术,并对其应用效果进行了评价。     

西双版纳区域气候变化对植物生长趋势的影响

目前全球变暖已经致使地球上生物群系的格局发生了显著的变化。高纬度地区的植物生长由此变得更加活跃,而热带地区植物生长的趋势仍然是一个具有争论的问题。西双版纳热带植物园地处中国西南地区,20世纪70年代以来,这里气候发生了显著的变化,其气温以每10年0.18℃的速度上升。本研究利用西双版纳热带植物园中的48种热带植物（28科）的株高生长数据（1974～2003年）来分析其对西双版纳区域气候变化的长期变化响应,通过对株高与气候因子的相关分析选出对植物株高生长影响最大的气候因子。结果表明,植物在研究期间的株高生长年间波动比较强烈,但没有表现出明显的趋势;植物的株高生长主要受到干热季（3、4月份）的日照时数（负）与月均最低气温（正）所影响,而干热季正是这些植物每年开始萌叶的时期;另外,降雨并没有对引种植物株高生长产生显著的影响;从2个关键因子的长期变化趋势来看,西双版纳气候变化将有利于保护植物的生长,进而将有利于植物园内热带植物的保护与保存。     

新疆棉田土壤固氮菌遗传多样性分析

利用ERIC-PCR和16SrDNA全序列测定方法,研究了新疆棉田土壤中分离获得的58株固氮菌的遗传多样性及系统发育。采用平均连锁法(UPGMA)分析ERIC-PCR的聚类结果表明在Watson距离为0.65左右时可以将供试菌株分为9个大群。选取ERIC-PCR各群中代表菌株进行16SrRNA全序列测定分析,结果表明这些菌株分别属于Enterobacter、Bacillus、Acinetobacter、Pseudomonas、Serratia和Yersinia6个属。     

Synthesis, characterization, and in vitro evaluation of long-chain hyperbranched poly(ethylene glycol) as drug carrier

A series of novel long-chain hyperbranched poly(ethylene glycol)s (LHPEGs) with biodegradable connections were designed and synthesized in one pot through proton-transfer polymerization using PEG and commercial glycidyl methacrylate as monomers and potassium hydride as catalyst. The LHPEGs were hydrolyzed at neutral pH resulting in the decrease of molecular weights. In vitro evaluation demonstrated that LHPEGs were biocompatible and displayed negligible hemolytic activity. The efficient cellular uptake of LHPEGs was confirmed by flow cytometry and confocal laser scanning microscopy. Moreover, conjugation of a model hydrophobic anticancer drug methotrexate to LHPEGs inhibited the proliferation of a human cervical carcinoma Hela cell line. MTT assay indicated that the conjugated methotrexate dose required for 50% cellular growth inhibition against Hela cells was 20 μg/mL. By combining the advantages of long-chain hyperbranched structure and PEG, LHPEG provides a promising drug carrier for therapeutic fields.     

Genetic Diversity and Geographical Differentiation of <Emphasis Type="Italic">Desmodium triflorum</Emphasis> (L.) DC. in South China Revealed by AFLP Markers

High levels of genetic variation enable species to adapt to changing environments and provide plant breeders with the raw materials necessary for artificial selection. In the present study, six AFLP primer pairs were used to assess the genetic diversity of Desmodium triflorum (L.) DC. from 12 populations in South China. A high percentage of polymorphic loci (P = 76.16%) and high total gene diversity (H _T = 0.310) were found, indicating that the genetic diversity of D. triflorum is high at the species level. Genetic diversity was also relatively high at the population level (P = 55.85%, H _e = 0.230). The coefficient of gene differentiation among populations (G _ST) was 0.255, indicating that while most genetic diversity resided within populations, there was also considerable differentiation among populations. AMOVA also indicated 24.29% of the total variation to be partitioned among populations (Φ_ST = 0.243). UPGMA clustering analysis based on genetic distances showed that the 12 populations could be separated into three subgroups: an eastern, a western, and a central-southern subgroup. However, a Mantel test revealed no significant correlation (r = 0.286, p = 0.983) between the geographical distances and genetic distances separating these populations; mountain barriers to gene flow and human disturbance may have confounded these correlations. The present study has provided some fundamental genetic data that will be of use in the exploitation of D. triflorum.     

Effect of solid bed-materials on vegetative cells of <Emphasis Type="Italic">Nostoc flagelliforme</Emphasis>

Nostoc flagelliforme was cultivated on three solid bed-materials which have different wettability. The results show that the wettability of solid bed-materials is very important to the need for water in N. flagelliforme, and also greatly affects photosynthetic activity, polysaccharide secretion and the morphology of the cells. Glass residue has the best wettability, followed by sand, and then nylon6 (PA6). We show that only sand is suitable for the growth of N. flagelliforme. When cultivated on sand for 100 days, the cells maintained a typical rosary-like shape. On glass residue, two to three vegetative cells formed a group with slime. On PA6, cells were in the form of loose group with slimes. N. flagelliforme is applicable to desert control as it cannot only grow on the sand, but also adhere to sand to form a biological crust.