广东地区汉族群体线粒体DNA 9bp序列缺失频率研究

旨在研究中国广东省部分地区汉族人群线粒体DNA RegionⅤ9bp序列缺失情况.采用PCR-PAGE和直接测序法对3个群体144份样本mtDNA RegionⅤ进行序列分析.结果只检测到标准型和短型(即9 bp缺失)两种多态.广东汉族人群的平均缺失频率为21.5%,广州、东莞和湛江汉族人群的缺失频率依次为20.8%、19.2%和25.0%.由此得出,广东汉族人群mtDNA 9 bp缺失频率较高,与其它地区汉族群体存在一定的差异.     

(±)-Praeruptorin A enantiomers exert distinct relaxant effects on isolated rat aorta rings dependent on endothelium and nitric oxide synthesis

Praeruptorin A is a coumarin compound naturally occurring in the roots of Peucedanum praeruptorum Dunn., a commonly used traditional Chinese medicine for the treatment of certain respiratory diseases and hypertension. Although previous studies indicated the relaxant effects of (±)-praeruptorin A on tracheal and arterial preparations, little is known about the functional characteristics of the enantiomers. In the present study, the two enantiomers were successfully isolated and identified by using a preparative Daicel Chiralpak AD-H column, and their relaxant effects on aorta rings were observed and compared. (+)-Praeruptorin A showed more potent relaxation than (?)-praeruptorin A against KCl- and phenylephrine-induced contraction of rat isolated aortic rings with intact endothelium. Removal of the endothelium remarkably reduced the relaxant effect of (+)-praeruptorin A but not that of (?)-praeruptorin A. Pretreatment of aortic rings with N^ω-nitro-l-arginine methyl ester (l-NAME, an inhibitor of nitric oxide synthase) or methylene blue (MB, a soluble guanylyl cyclase inhibitor) resulted in similar changes of the relaxant effects of the two enantiomers to endothelium removal. Molecular docking studies also demonstrated that (+)-praeruptorin A was in more agreement to nitric oxide synthase pharmacophores than (?)-praeruptorin A. On the other hand, the two enantiomers of praeruptorin A could slightly attenuate the contraction of rat aortic rings induced by internal Ca²⁺ release from sarcoplasmic reticulum (SR). These findings indicated that (+)-praeruptorin A and (?)-praeruptorin A exerted distinct relaxant effects on isolated rat aorta rings, which might be mainly attributed to nitric oxide synthesis catalyzed by endothelial nitric oxide synthase.     

赤水河鱼类资源的现状与保护

赤水河是长江上游右岸一级支流,为长江上游珍稀特有鱼类国家级自然保护区的重要组成部分。为了了解赤水河鱼类资源现状,于2007年4-10月在赤水河流域进行了鱼类资源调查。在干、支流共51个采样点采集了鱼类标本;对茅台镇、赤水市和合江县三个江段的渔获物进行了统计和分析。共采集到鱼类119种(亚种),隶属于5目16科75属。其中25种为该水域的新记录;34种为长江上游特有鱼类,尤其是宽唇华缨鱼(Sinocrossocheilus labiatus)仅分布于赤水河。在上、中、下游分别采集到鱼类36、61和100种。宽鳍鱲(Zacco platypus)、中华倒刺鲃(Spinibarbus sinensis)、光泽黄颡鱼(Pelteobagrus nitidus)、张氏(Hemiculter tchangi)和蛇鮈(Saurogobio dabryi)为赤水河中主要的经济鱼类,同时,各江段渔获物的组成也存在一定的差别。本研究表明,赤水河流域鱼类种类相对丰富,但过度捕捞和涉水活动导致鱼类资源出现了一定程度的衰减。     

Roles for Gcn5 in promoting nucleosome assembly and maintaining genome integrity

The process of coordinated DNA replication and nucleosome assembly, termed replication-coupled (RC) nucleosome assembly, is important for the maintenance of genome integrity. Loss of genome integrity is linked to aging and cancer. RC nucleosome assembly involves deposition of histone H3–H4 by the histone chaperones CAF-1, Rtt106 and Asf1 onto newly-replicated DNA. Coordinated actions of these three his-tone chaperones are regulated by modifications on the histone proteins. One such modification is histone H3 lysine 56 acetylation (H3K56Ac), a mark of newly-synthesized histone H3 that regulates the interaction between H3–H4 and the histone chaperones CAF-1 and Rtt106 following DNA replication and DNA repair. Recently, we have shown that the lysine acetyltransferase Gcn5 and H3 N-terminal tail lysine acetylation also regulates the interaction between H3–H4 and CAF-1 to promote the deposition of newly-synthesized histones. Genetic studies indicate that Gcn5 and Rtt109, the H3K56Ac lysine acetyltransferase, function in parallel to maintain genome stability. Utilizing synthetic genetic array analysis, we set out to identify additional genes that function in parallel with Gcn5 in response to DNA damage. We summarize here the role of Gcn5 in nucleosome assembly and suggest that Gcn5 impacts genome integrity via multiple mechanisms, including nucleosome assembly.Key words: Gen5, Rtt109, chromatin, nucleosome assembly, genome integrity     

Viral Infection Affects Sucrose Responsiveness and Homing Ability of Forager Honey Bees,Apis mellifera L.

Honey bee health is mainly affected by Varroa destructor, viruses, Nosema spp., pesticide residues and poor nutrition. Interactions between these proposed factors may be responsible for the colony losses reported worldwide in recent years. In the present study, the effects of a honey bee virus, Israeli acute paralysis virus (IAPV), on the foraging behaviors and homing ability of European honey bees (Apis mellifera L.) were investigated based on proboscis extension response (PER) assays and radio frequency identification (RFID) systems. The pollen forager honey bees originated from colonies that had no detectable level of honey bee viruses and were manually inoculated with IAPV to induce the viral infection. The results showed that IAPV-inoculated honey bees were more responsive to low sucrose solutions compared to that of non-infected foragers. After two days of infection, around 10⁷ copies of IAPV were detected in the heads of these honey bees. The homing ability of IAPV-infected foragers was depressed significantly in comparison to the homing ability of uninfected foragers. The data provided evidence that IAPV infection in the heads may enable the virus to disorder foraging roles of honey bees and to interfere with brain functions that are responsible for learning, navigation, and orientation in the honey bees, thus, making honey bees have a lower response threshold to sucrose and lose their way back to the hive.     

蛋白G IgG Fc段结合域的克隆表达及功能研究

旨在研究蛋白G IgG Fc段结合域(PGFB)的克隆、表达及其抗体结合功能,用于抗体的纯化.根据PGFB的氨基酸序列,选择大肠杆菌偏爱的密码子,设计并合成了4个寡核苷酸片段.通过重叠延伸PCR方法合成了PGFB DNA片段,测序鉴定后克隆至原核表达系统pET-28a-c(+)上,转化大肠杆菌,获得表达菌株;IPTG诱导表达PGFB,经Ni+-NTA琼脂糖凝胶层析纯化后偶联到琼脂糖凝胶6B上,用其纯化多克隆抗体.结果显示,PGFB在大肠杆菌BL21(DE3)中获得高效表达,纯化后纯度达到90%以上,相对分子量为12.25 kD,与预期值相符.此外,偶联产物纯化多克隆抗体达到了良好的效果,每毫升基质可结合20 mg抗体.本研究克隆构建并高效表达了具有较好抗体亲和能力的PGFB,为多克隆抗体的快速纯化提供了方便.     

Dendrite‐Free Metallic Lithium in Lithiophilic Carbonized Metal–Organic Frameworks

Although metallic lithium is a promising anode material due to its high theoretical capacity, the uncontrollable growth of lithium dendrites and infinite volume change hamper its practical applications. Here, the lithiophilic property of carbonized metal–organic frameworks (cMOFs) is harnessed with zinc species to achieve a uniform lithium‐cMOFs (Li‐cMOFs) hybrid via a molten lithium infusion approach. In the resultant Li‐cMOFs, not only are abundant Zn clusters are uniformly confined and dispersed in the matrix, serving as homogeneous nucleation sites to guide Li deposition, but also the 3D conductive porous structure enables the homogenization of the distributions of electric field and Li ion flux, avoiding the formation of lithium dendrites. Hence, this hybrid exhibits superior electrochemical performance with a very low voltage hysteresis and a good cycle life. This provides a new manner to achieve a series of stable metallic lithium anodes based on the large family of metal–organic frameworks with tunable metal species.     

浙江天童20ha常绿阔叶林动态监测样地的群落特征

常绿阔叶林是我国东部低海拔地区的典型植被,基于大型动态监测样地的群落特征分析是揭示其生物多样性维持机制的基础.作者在天章国家森林公园建立了20 ha的样地,并完成了第一次群落学特征调查和分析.结果显示,样地内共有胸径≥1 cm的木本植物152种94,603株,隶属51科94属.重要值最大的前3个科依次是山茶科、樟科和壳斗科.属水平上热带区系成分占总属数的52.1%,温带区系成分占42.6%.常绿物种在样地内占绝对优势,占总重要值的80.3%.重要值最大的3个种依次是细枝柃(Eurya loquaiana)、黄丹木姜子(Litsea elongata)和南酸枣(Choerospondias axiliaris);稀有种共计55种,占总物种数的36.2%.木本植物整体径级结构呈逆"J"字型.萌枝分枝 情况表明,常绿物种的萌、分枝能力强于落叶物种.此结果表明天童常绿阔叶林物种组成丰富,群落成熟稳定,更新良好,反映了亚热带东部常绿阔叶林的典型特征.