Molecular dynamics simulations to investigate the effects of zinc ions on the structural stability of the c-Cbl RING domain

In eukaryotic cells, ubiquitylation of proteins plays a critical role in regulating diverse cell processes by the ubiquitin activating enzyme (E1), ubiquitin-conjugating enzyme (E2), and ubiquitin protein ligase (E3). E3 is the key component that confers specificity to ubiquitylation and directs the conjugation of ubiquitin to a specific target protein. RING domains are small structured protein domains that require the coordination of zinc ions for a stable tertiary fold and some of them are involved in the E3 family. In this study, we reported the detailed relationships between the two zinc ions and the structural stability of the c-Cbl RING domain by molecular dynamics simulations. Our results show that these two zinc ions play an important role in maintaining both the secondary and tertiary structural stabilities of the c-Cbl RING domain. Our results also reveal that the secondary structural stability of the c-Cbl RING domain is mainly determined by the hydrogen-bonding networks in or near the two zinc ion binding sites. Our results further demonstrate that zinc ion binding site 2 is more structurally stable than site 1.     

家蚕微孢子虫感染对家蚕海龟蛋白(Bmtutl)基因表达水平的影响

【目的】本研究旨在阐明家蚕微孢子虫Nosema bombycis感染不同时间对家蚕Bombyx mori幼虫不同组织中家蚕海龟蛋白(Bombyx Turtle, Bmtutl)基因表达水平的影响,为揭示家蚕微孢子虫的侵染机制奠定基础。【方法】利用生物信息学方法对家蚕海龟蛋白3种亚型Bmtutl-464, Bmtutl-519和Bmtutl-810的序列结构特征进行了分析;利用qPCR检测家蚕微孢子虫感染后12, 24, 48, 72, 96和120 h,家蚕幼虫中肠、血淋巴与脂肪体组织中Bmtutl-464, Bmtutl-519和Bmtutl-810基因表达水平的变化情况。【结果】家蚕海龟蛋白3种亚型的二级结构均主要由无规则卷曲、α螺旋、β转角和延伸链组成,其中无规则卷曲所占比例最高。但是PredictProtein分析发现,Bmtutl-464, Bmtutl-519和Bmtutl-810之间的蛋白/多核苷酸结合位点存在较大差异。qPCR结果表明,感染家蚕微孢子虫后,家蚕幼虫中肠、血淋巴与脂肪体组织中Bmtutl-464, Bmtutl-519和Bmtutl-810基因的整体表达处于被抑制状态,尤其在脂肪体中最为明显：Bmtutl-519和Bmtutl-810基因的表达在家蚕微孢子虫感染家蚕后的72 h开始受到显著抑制,特别是Bmtutl-519基因,其相对表达水平均不到对照的5.0%。【结论】家蚕海龟蛋白这3种亚型的序列结构特征存在较大差异,家蚕微孢子虫感染在一定程度抑制了家蚕幼虫中肠、血淋巴与脂肪体组织中Bmtutl-464, Bmtutl-519和Bmtutl-810基因尤其是Bmtutl-519的表达。结果说明,与其他两种家蚕海龟蛋白亚型相比,Bmtutl-519蛋白可能在家蚕微孢子虫侵染宿主的过程中起主要作用。     

Dilated cardiomyopathy caused by tissue-specific ablation of SC35 in the heart

Many genetic diseases are caused by mutations in cis-acting splicing signals, but few are triggered by defective trans-acting splicing factors. Here we report that tissue-specific ablation of the splicing factor SC35 in the heart causes dilated cardiomyopathy (DCM). Although SC35 was deleted early in cardiogenesis by using the MLC-2v-Cre transgenic mouse, heart development appeared largely unaffected, with the DCM phenotype developing 3-5 weeks after birth and the mutant animals having a normal life span. This nonlethal phenotype allowed the identification of downregulated genes by microarray, one of which was the cardiac-specific ryanodine receptor 2. We showed that downregulation of this critical Ca2+ release channel preceded disease symptoms and that the mutant cardiomyocytes exhibited frequency-dependent excitation-contraction coupling defects. The implication of SC35 in heart disease agrees with a recently documented link of SC35 expression to heart failure and interference of splicing regulation during infection by myocarditis-causing viruses. These studies raise a new paradigm for the etiology of certain human heart diseases of genetic or environmental origin that may be triggered by dysfunction in RNA processing.     

家族性高胆固醇血症患者低密度脂蛋白受体基因新突变位点的鉴定

家族性高胆固醇血症(hypercholesterolemia familial,FH)是由于低密度脂蛋白受体(low density lipoprotein receptor,LDLR)基因突变导致的常染色体显性遗传性疾病,临床上表现为多发黄色瘤、高水平血浆LDL、早发性冠心病及有阳性家族史。本研究通过临床症状结合血脂测定诊断出一个FH家系,其纯合子FH患者的血浆总胆固醇水平高达19．05mmol／L,LDL达17．06mmol／L,并有黄色瘤;而杂合子FH患者的血浆总胆固醇水平为7．96mmol／L,LDL为5．55mmol/L,并有心绞痛症状和黄色瘤。我们对该FH家系患者LDLR基因的PCR扩增DNA片段进行测序,发现纯合子FH患者LDLR基因Exon4区域内发生了GAG683GCG突变,即编码LDLR第683位的谷氨酸被丙氨酸替换,而杂合子FH患者该位点呈现杂合突变。此基因型与临床诊断遗传谱完全一致。同时,利用获得Epstein-Barr(EB)病毒转化型人永生淋巴细胞株(EBV-Ls)与荧光探针DiI标记的LDL结合反应,再通过流式细胞仪检测结果显示,具有功能性LDLR的EBV-Ls细胞比例,在纯合子FH患者(7．02％)和杂合子FH患者(62．64％)均比健康对照者(84．69％)低,纯合子FH患者LDLR活性仅为健康对照者的8．29％、而杂合子FH患者LDLR活性约为健康对照者的73．96％,前者呈现非常显著的降低。这些EBV-Ls细胞LDLR的功能变化分析,有力地支持了该FH家系的临床诊断和DNA测序结果。经查阅最新的UMD-LDLR完全版证实,本研究发现鉴定的GAG683GCG突变是人LDLR基因的新突变位点。     

Nucleic acid binding activity of pns6 encoded by genome segment 6 of rice ragged stunt oryzavirus

Rice ragged stunt disease, caused by rice ragged stuntoryzavirus (RRSV), was first discovered in 1976–1977 inIndonesia and Philippines [1]. Subsequently the diseasewas found in most rice-growing countries in south-easternand far-eastern Asia [2] and may inflict heavy loss on thecrop. RRSV is the type species of the genus Oryzavirus in thefamily Reoviridae. The virus particle is icosahedral witha diameter of about 65–70 nm and the genome consistsof 10 double stranded RNA (dsRNA) segm…     

Expression of a modified Cry1Ie gene in E. coli and in transgenic tobacco confers resistance to corn borer

The wild-type Crylle gene from Bacillus thuringiensis was modified for its efficient expression in transgenic plants. Modified Crylle gene (designated as Cryllem) was cloned into prokaryotic expressionvector pET28b and its expression in E.coli was confirmed by SDS-PAGE analysis. Bioassays using crude expression products in E.coli revealed that CrylIem protein had a similar toxicity to corn borer as wild-type CrylIe. CrylIem gene was then inserted downstream of the maize ubiquitin-1 promoter in plant expression vector p3301. Transgenic tobacco plants carrying Cryllem showed insecticidal activity against corn borer.     

一种浓缩噬藻体的反冲超滤技术

噬藻体(Cyanophage)是一类感染蓝藻的病毒,形态上同于噬菌体,近期的研究表明,噬藻体作为水体环境中活跃的动态因子,在控制水体初级生产力和有害藻类水华(Harmful Algal Bloom,HAB)方面可能发挥着重要的作用,甚至影响水体生态系统中食物链的结构,因此研究水体中噬藻体的生理生态学特性对于了解其生态功能是非常重要的,但是由于自然水体中的噬藻体浓度往往较低,难以直接对其进行定性或定量研究,所以对天     

Co-localization of hypocretin-1 and hypocretin-2 in the cat hypothalamus and brainstem

Hypocretin-1 (hcrt-1) and hypocretin-2 (hcrt-2) are two recently discovered hypothalamic neuropeptides. In the present study, using double immunofluorescent techniques, the co-localization of hcrt-1 and hcrt-2 was examined in neuronal soma and fibers/terminals located, respectively, in the cat hypothalamus and brainstem. In the hypothalamus, all hcrt-1 positive neuronal soma also displayed hcrt-2 immunoreactivity. In the brainstem, both hcrt-1 and hcrt-2 antibodies labeled the same fibers/terminals, indicating that hcrt-1 and hcrt-2 co-localize not only in the neuronal soma (hypothalamus) but also in their fibers/terminals (brainstem). If both peptides are released following neuronal activity, then the distinct effects of these peptides in the brain are likely to depend on the types of postsynaptic receptors that are activated.     

两种肚倍型蚜虫之两种同功酶及可溶性蛋白的比较

应用电泳分析方法,对青麸杨上幼锤形信子与长枣形倍子内蚜虫进行了酯酶同功酶、过氧化物同功酶及可溶蛋白质的比较研究。结果表明：经形态学鉴定同为肚倍蚜可致瘿形成纺锤形与长枣形倍子。2种倍形内蚜虫在可溶性蛋白及酯酶同功酶上有较大差异。相异系数分别为02571,0067。说明肚倍蚜种内已出现分化,不同变形体倍子内蚜虫在分子水平上已具有向不同生物型分化的趋势。     

呼吸活性的下降可解释水分亏缺对银合欢根瘤固氮酶活性的抑制(英)

在温室条件下研究了水分亏缺对银合欢根瘤的水分关系、固氮酶活性（乙炔还原活性）、呼吸活性以及蔗糖代谢有关酶活性的影响。随着土壤含水量的下降,根瘤水势也相继下降。土壤干旱不但显著地抑制了根瘤乙炔还原的活性,而且对根瘤的呼吸活性、ATP的产生以及催化蔗糖降解的碱性转化酶和蔗糖合成酶的活性也具强烈的抑制作用。然而,根瘤可溶性总糖含量则不受土壤干旱的影响。用呼吸抑制剂DNP处理根瘤后,其固氮酶活性、呼吸活性及ATPI含量都受到极显著的抑制。这都表明,水分胁迫对根瘤呼吸活性及ATP产生的抑制可解释干旱条件下固氮酶活性的下降。