Co-segregation of the T1095C with the A1555G mutation of the mitochondrial 12S rRNA gene in a patient with non-syndromic hearing loss

We reported here the clinical and molecular characterization of a Chinese subject with childhood-onset hearing impairment. Clinical evaluations showed that the patient suffered from profound and non-syndromic sensorineural hearing loss with flat configurations. Sequence analysis of the mitochondrial 12S rRNA and tRNA^Ser(UCN) genes led to the identification of double deafness-associated mutations of A1555G and T1095C in the 12S rRNA gene which apparently in the homoplasmic forms. In additional, there was no other functionally significant nucleotide variants found in this subject. As previous studies have indicated that the A1555G mutation was a primary contributing factor underlying the development of deafness but not sufficient to produce clinical phenotype, the co-segregation of two mitochondrial DNA mutations raises the possibility that the T to C transition at position 1095 plays a role in the phenotypic expression of deafness-associated A1555G mutation. Actually, the T1095C mutation disrupted an evolutionarily conserved base-pair at stem-loop of helix 25 of 12S rRNA, resulting in impaired translation in mitochondrial protein synthesis and a significant reduction of cytochrome c oxidase activity. As a result, it may enhance the biochemical defect in patient carrying the A1555G mutation, thus changing the age of onset and the severity of hearing impairment.     

Thr but Asn of the N-glycosylation sites of PrP is indispensable for its misfolding

Prion protein (PrP) contains two N-linked glycosylation sites. It is unknown which amino acid substitution contributes most efficiently to the abolishment of N-linked glycosylations. To define the influence of amino acid substitution at the N-linked glycosylation sites on the conversion efficiency of mouse PrP, we tested each of all 19 amino acid substitutions at either one of the N-linked glycosylation sites (codon 180, 182, 196 or 198). The conversion efficiency of the mutagenized PrP was highly dependent on the newly introduced amino acid itself regardless of the absence of N-linked glycosylation in scrapie-infected mouse neuroblastoma cells. The majority of mutant PrP with substitutions at the Asn residues of the N-linked glycosylation sites were conversion-competent, whereas most mutant PrP with substitutions at the Thr residues were conversion-incompetent. These findings emphasize that the Asn residues of the N-linked glycosylation sites are replaceable to abolish N-linked glycosylations without directly affecting the protein function.     

重庆缙云山针阔混交林林隙树木更替规律研究

 研究了重庆缙云山大面积分布的亚热带次生性针阔混交林林隙树木更替规律,预测了该类型林林隙演替趋势。结果表明：马尾松(Pinus massoniana)种群表现出强烈的相互更替模式,四川大头茶(Gordonia acuminata)、四川山矾(Symplocos setchuanensis)等常绿阔叶树种自我更替与相互更替两种模式共存;林隙现实树木更替过程不能维持群落现有组成;Markov转移矩阵分析表明未来林冠层组成中马尾松种群将失去优势地位,整个群落将由针阔混交林向常绿阔叶林方向演替。     

Pancreatic cancer-derived exosomal microRNA-19a induces β-cell dysfunction by targeting ADCY1 and EPAC2

New-onset diabetes mellitus has a rough correlation with pancreatic cancer (PaC), but the underlying mechanism remains unclear. This study aimed to explore the exosomal microRNAs and their potential role in PaC-induced β-cell dysfunction. The pancreatic β cells were treated with isolated exosomes from PaC cell lines, SW1990 and BxPC-3, before measuring the glucose-stimulated insulin secretion (GSIS), validating that SW1990 and BxPC-3 might disrupt GSIS of both β cell line MIN6 and primary mouse pancreatic islets. The difference in expression profiles between exosomes and exosome-free medium of PaC cell lines was further defined, revealing that miR-19a secreted by PaC cells might be an important signaling molecule in this process. Furthermore, adenylyl cyclase 1 (Adcy1) and exchange protein directly activated by cAMP 2 (Epac2) were verified as the direct targets of exogenous miR-19a, which was involved in insulin secretion. These results indicated that exosomes might be an important mediator in the pathogenesis of PaC-DM, and miR-19a might be the effector molecule. The findings shed light on the pathogenesis of PaC-DM.     

转基因烟草中的海藻糖测定

The \%E.coli\% trehase synthalose gene(\%otsA\%) was transferred into \%Nicotiana tabacum\% mediated by \%Agrobacterium\%, but the method for detecting low concentration of trehalose in transgenic plant was not available.The high performance liquid chromatograph(HPLC) with evaporative light\|scatting detector (ELSD) using water:methyl cyanide(1∶2\^6 v/v) as mobile phase was established in this work. An ODS column Zorbax RX\|SIL was employed. The trehalose detection limits of ELSD was 5mg/L. From the linear…     

中国家蚕抗菌肽人工合成类CMⅣ基因在甜菜夜蛾虫体中的表达

将人工合成的中国家蚕抗菌肽类CMⅣ基因与抗菌肽信号肽基因连接 ,经EcoRⅠ、HindⅢ双酶切后 ,克隆于pFASTBacⅠ的EcoRⅠ、HindⅢ酶切位点之间 ,得到重组转座载体pFASTBac ABP ,经测序证明阳性克隆正确。将重组转座载体转化HD1 0Bac大肠杆菌 ,得到重组Bacmid ABP。将重组Bacmid转染sf2 1细胞及感染甜菜夜蛾 (Laphygmaexigua)幼虫 ,在培养细胞上清及虫体血淋巴中均测到抗菌活性。经Northernblotting证明感染甜菜夜蛾幼虫中有类CMⅣmRNA的存在。且表达产物在酸性电泳中电泳行为与天然抗菌肽CMⅣ组分相似。为进一步利用昆虫细胞及虫体生产抗菌肽药物打下了基础。     

大肠杆菌海藻糖合成酶基因对提高烟草抗逆性能的研究

编码大肠杆菌海藻糖合成酶的otsA基因由农杆菌介导引入野生型烟草植株并在花椰菜花叶病毒启动子序列 (CaMV35S)控制下获得表达。蒸发光散射高效液相层析法测定海藻糖实验表明 ,转基因烟草能够合成海藻糖 ,合成量达 1 4μg g叶片湿重 ;转基因烟草表现为耐盐性生长、干燥失重缓慢等抗逆表型。说明海藻糖合成酶otsA基因的引入 ,改变了烟草的糖代谢途径 ,同时也提高了植物的耐盐碱、耐干旱特性。     

Biosurfactants of MEL-A increase gene transfection mediated by cationic liposomes.

Many microorganisms growing on water-insoluble substrates have been known to produce surface-active compounds called biosurfactants. Although biosurfactants have received increasing attention due to their special properties, there has been no information available until now of a role for them with regard to gene transfection. Thus, we studied here the effects of biosurfactants on gene transfection by cationic liposomes with a cationic cholesterol derivative. Our results showed clearly that a biosurfactant of mannosylerythritol lipid A (MEL-A) increased dramatically the efficiency of gene transfection mediated by cationic liposomes with a cationic cholesterol derivative. Among them, the liposomes with a cationic cholesterol derivative, cholesteryl-3 beta-carboxyamindoethylene-N-hydroxyethylamine (I), were much more effective for gene transfection than the liposomes with DC-Chol (cholesteryl-3 beta-oxycarboxyamidoethylenedimethylamine) or liposomes without MEL-A in various cultured cells. This demonstrates that this new finding has great potential in the experiment of gene transfection and gene therapy mediated by nonviral vectors such as cationic liposomes.