关于木本石松植物鳞皮木属的正确名称

讨论了木本石松植物鳞皮木属Lepidophloios Stemberg的正确名称。基于Stemberg 1825年的原始描述和相关文献以及模式标本,Lepidophloios实际上是一个晚出的拼写变体,它的原始拼写为Lepidopfloyos。根据《国际植物命名法规》（维也纳法规规则60．1和61．1）,Lepidofloys Stemberg应该是鳞皮木属的正确名称。作者给出了鳞皮木属模式标本的图片和描述。     

六个石蒜居群的核型及四倍体石蒜的发现

染色体与核型的变化是植物系统发育和进化的一个重要方面。石蒜属Lycoris植物特别是石蒜L.radiata在染色体数目和核型上存在较大的变异。通过对不同居群的石蒜核型研究,可以为石蒜和石蒜属植物的核型演化及演化机制提供一些重要的基础资料。本文对分布于中国安徽省和浙江省的6个石蒜居群进行了细胞学研究。结果表明,6个石蒜居群的染色体数目和核型分别为：霍山居群2n=44=28st＋8t＋8T,2n=22=6st＋12t＋4T;黄山居群2n=22=22t,2n=22=18st＋4t,2n=21=12st＋7t＋2T;滁州居群2n=33=33t;马鞍山居群2n=33=18st＋15T,2n=25=1m＋20st＋2t＋2T;宣城居群2n=22=20st＋2T,2n=21=1m＋20st;杭州居群2n=22=12st＋4t＋6T,2n=21=18st＋3t。其中,部分居群的核型类型为首次报道;并首次发现了四倍体的石蒜居群。此外,对石蒜的核型进化和多倍体起源进行了初步探讨。     

植物病毒诱导的基因沉默效应的分子机制

主要从病毒诱导的基因沉默体系中植物与病毒的相互作用、VIGS涉及的信号分子和移动方式以及靶基因的沉默和病毒载体的复制关系介绍和分析植物病毒诱导的基因沉默效应的分子机制,并进一步分析此种体系在植物基因功能研究中应用的研究进展。     

beta-sitosterol decreases irradiation-induced thymocyte early damage by regulation of the intracellular redox balance and maintenance of mitochondrial membrane stability

Both radiation injury and oxidation toxicity occur when cells are exposed to ion irradiation (IR), ultimately leading to apoptosis. This study was designed to determine the effect of beta-sitosterol (BSS) on early cellular damage in irradiated thymocytes and a possible mechanism of effect on irradiation-mediated activation of the apoptotic pathways. Thymocytes were irradiated (6 Gy) with or without BSS. Cell apoptosis and apoptosis-related proteins were evaluated. BSS decreased irradiation-induced cell death and nuclear DNA strand breaks while attenuating intracellular reactive oxygen species (ROS) and increasing the activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). BSS decreased the release of cytochrome c from mitochondria to the cytosol and the mitochondrio-nuclear translocation of apoptosis-inducing factor (AIF). Furthermore, BSS partially inhibited the radiation-induced increase of cleaved caspase 3 and cleaved PARP, and attenuated the activation of JNK and AP-1. In addition, evidence suggests that ROS generated by irradiation are involved in this course of cell damage. The results indicate that BSS confers a radioprotective effect on thymocytes by regulation of the intracellular redox balance which is carried out via the scavenging of ROS and maintenance of mitochondrial membrane stability.     

Essential dynamics sampling study of adenylate kinase: comparison to citrate synthase and implication for the hinge and shear mechanisms of domain motions

Essential dynamics sampling simulations of the domain conformations of unliganded Escherichia coli adenylate kinase have been performed to determine whether the ligand-induced closed-domain conformation is accessible to the open unliganded enzyme. Adenylate kinase is a three- domain protein with a central CORE domain and twoflanking domains, the LID and the NMPbind domains. The sampling simulations were applied to the CORE and NMPbind domain pair and the CORE and LID domain pair separately. One aim is to compare the results to those of a similar study on the enzyme citrate synthase to determine whether a similar domain-locking mechanism operates in adenylate kinase. Although for adenylate kinase the simulations suggest that the closed-domain conformation of the unliganded enzyme is at a slightly higher free energy than the open for both domain pairs, the results are radically different to those found for citrate synthase. In adenylate kinase the targeted domain conformations could always be achieved, whereas this was not the case in citrate synthase due to an apparent free-energy barrier between the open and closed conformations. Adenylate kinase has been classified as a protein that undergoes closure through a hinge mechanism, whereas citrate synthase has been assigned to the shear mechanism. This was quantified here in terms of the change in the number of interdomain contacting atoms upon closure which showed a considerable increase in adenylate kinase. For citrate synthase this number remained largely the same, suggesting that the domain faces slide over each other during closure. This suggests that shear and hinge mechanisms of domain closure may relate to the existence or absence of an appreciable barrier to closure for the unliganded protein, as the latter can hinge comparatively freely, whereas the former must follow a more constrained path. In general though it appears a bias toward keeping the unliganded enzyme in the open-domain conformation may be a common feature of domain enzymes.     

Hydrolase-catalyzed Michael addition of 1,3-dicarbonyl compounds to α,β-unsaturated compounds in organic solvent

A novel strategy to perform Michael additions between 1,3-dicarbonyl compounds and α,β-unsaturated compounds was developed by the catalysis of hydrolase. We found that 11 hydrolase could catalyze the enzymatic Michael addition reaction to form the carbon–carbon bond. In 2-methyl-2-butanol d-aminoacylase showed high Michael addition activity. The influence of substrate and Michael acceptor structure on Michael addition was evaluated systematically. Some control experiments demonstrated that the active site of d-aminoacylase was responsible for the enzymatic Michael addition reaction. This novel Michael addition activity of hydrolase is of practical significance in expanding the application of enzymes and in the evolution of new biocatalysts.     

Improved biological characteristics of poly(L-lactic acid) electrospun membrane by incorporation of multiwalled carbon nanotubes/hydroxyapatite nanoparticles

Significant effort has been devoted to fabricating various biomaterials to satisfy specific clinical requirements. In this study, we developed a new type of guided tissue regeneration (GTR) membrane by electrospinning a suspension consisting of poly( l-lactic acid), multiwalled carbon nanotubes, and hydroxyapatite (PLLA/MWNTs/HA). MWNTs/HA nanoparticles were uniformly dispersed in the membranes, and the degradation characteristics were far improved. Cytologic research revealed that the PLLA/MWNTs/HA membrane enhanced the adhesion and proliferation of periodontal ligament cells (PDLCs) by 30% and inhibited the adhesion and proliferation of gingival epithelial cells by 30% also, compared with the control group. After PDLCs were seeded into the PLLA/MWNTs/HA membrane, cell/membrane composites were implanted into the leg muscle pouches of immunodeficient mice. Histologic examinations showed that PDLCs attached on the membranes functioned well in vivo. This new type of membrane shows excellent dual biological functions and satisfied the requirement of the GTR technique successfully in spite of a monolayer structure. Compared with other GTR membranes on sale or in research, the membrane can simplify the manufacturing process, reduce the fabrication cost, and avoid possible mistakes in clinical application. Moreover, it does not need to be taken out after surgery. PLLA/MWNTs/HA membranes have shown great potential for GTR and tissue engineering.     

转录因子cpcR同源基因cpcR-c1和cpcR-t的功能鉴定

苏云金芽胞杆菌（Bacillus thuringiensis,Bt） LM1212菌株与典型的Bt菌株表型不同,可分化形成芽胞、形成细胞和晶体产生细胞。在LM1212菌株中,转录因子CpcR不仅参与了细胞分化过程,而且能够激活晶体蛋白基因cry35-like的启动子(P₃₅)。【目的】筛选cpcR同源基因,验证其生物学功能。【方法】本研究克隆了2个cpcR同源基因,来源于蜡样芽胞杆菌的cpcR-c1和来源于东洋芽胞杆菌的cpcR-t,将cpcR及其同源基因分别构建在pHT304-P₃₅-gfp、pHT304-P₃₅-lacZ报告载体上,获得的重组质粒转入无cpcR基因且无晶体蛋白基因的Bt HD73^–菌株中。利用激光共聚焦显微镜观察重组菌HD^–(cpcR-c1-P₃₅-gfp)和HD^–(cpcR-t-P₃₅-gfp)的细胞表型并进行芽胞计数实验。测定HD^–(cpcR-c1-P_35<...