Identification and characterization of a chondroitin synthase from Avibacterium paragallinarum

Applied Microbiology and Biotechnology - Avibacterium paragallinarum is a Gram-negative bacterium that causes infectious coryza in chicken. It was reported that the capsule polysaccharides...     

Secondary structure and 3D homology modeling of grass carp (Ctenopharyngodon idellus) major histocompatibility complex class I molecules

No information to date is available on the structure of fish major histocompatibility complex (MHC) class I and beta2-microglobulin (beta2m) proteins. In the present study, grass carp (Ctenopharyngodon idellus) MHC class I (Ctid-MHC I) and beta(2)-microglobulin (Ctid-beta2m) genes were expressed as soluble maltose binding protein (MBP)-proteins and purified in a pMAL-p2X/Escherichia coli TB1 system. The expressed proteins were purified on amylase affinity columns followed by DEAE-Sepharose. The purified products were identified by Western blotting with anti-MBP polyclonal antibodies. The MBP-Ctid-MHC I and MBP-Ctid-beta2m were cleaved separately with Factor Xa, mixed together and purified on DEAE-Sepharose. The secondary structures were analyzed by circular dichroism (CD) spectrophotometry. The three-dimensional (3D) structure of their peptide-binding domain (PBD) was modeled based sequence homology. The sequence lengths of the alpha-helix, beta-sheet, turn, and random coil in the Ctid-MHC I protein were 79aa, 75aa, 20aa, and 99aa, respectively. In the 97aa of Ctid-beta2m, the contents of the alpha-helix, beta-sheet, turn, and random coil were 0aa, 41aa, 12aa, and 44aa, respectively. The Ctid-beta2m protein displayed a typical beta-sheet. Homology modeling of the Ctid-MHC I and Ctid-beta2m proteins demonstrated similarities with the structure of human MHC class I proteins.     

Cloning and characterization of a non-TIR-NBS-LRR type disease resistance gene analogue from peach.

Cloning of plant disease resistant genes is greatly helpful for disease resistant breeding in plants and the insight of resistance mechanism. However, there are less relevant researches in peach [prunus persica (L.) Batch]. In this study, four NBS-LRR type resistance gene analogs (RGAs) were cloned from genomic DNA of peach. The PNBS2 fragment was also amplified from peach cDNA and the full-length cDNA of PNBS2 (PRPM1, GenBank accession no. AY599223) has been cloned. Sequence analysis indicated that the cDNA of PRPM1 is 3007 bp in length and that the contained ORF encodes for a polypeptide of 917 amino acids. Compared with known NBS-LRR genes, it presented relatively high amino acid sequence identity. The polypeptide has typical structure of non-TIR-NBS-LRR genes, with NB-ARC, LZ, LRR and transmembrane domains. Southern analysis indicated that the PRPM1 gene might be a single copy in peach genome. Northern blot and RT-PCR analysis showed that the expression of PRPM1 was not induced by salicylic acid (SA) in peach young leaves. The isolation of putative resistance genes from peach provided useful bases for studying the structure and function of peach disease-resistance relating genes and disease resistant genetic breeding in peach.     

用甘蓝苗连续饲养小菜蛾的技术

室内实验结果表明 :在 ( 2 5± 1 )℃、相对湿度 5 0 %～ 70 %、光周期 1 6L∶8D条件下 ,用甘蓝苗(BrassicanapusL .)饲养小菜蛾PlutellaxylostellaL .可取得较好的饲养结果 ,连续饲养多代种群未出现退化现象 ,能够得到大量发育整齐的供试虫源。在低温 ( 4℃ )条件下 ,卵冷藏 7d ,孵化率 77 8% ,蛹冷藏 1 5d化蛹率 86 9% ,冷藏后卵和蛹的发育等与各自的对照基本一致 ,可以较好地调控小菜蛾发育进度 ,便于取得虫龄基本一致的虫源。     

我国巴马小型猪SLA-2基因克隆及分子特征

为研究我国巴马小型猪SLA-Ⅰ分子特征,设计引物克隆了SLA-Ⅰ类分子SLA-2基因(SLA-2bm),并通过分子生物学软件分析其分子特征。经克隆及序列测定分析,SLA-2bm为1119bp,其中3~1097为ORF区,共编码364个氨基酸,分别在第125、188、227和283位置出现半胱氨酸残基,含有两对链内二硫键。氨基酸同源性分析显示SLA-2bm与其它SLA-2、SLA-3和SLA-1序列的同源率分别为88.4%~96.4%、88.3%~90.5%和87.7%~92.7%。系统进化树显示SLA-2bm与其它SLA-2等位基因在遗传关系上相对独立,进化程度较低;各功能区分析,SLA-2bm与人HLA-A2和小鼠H-2K分子结构相似,且保留了人HLA-A2基因的部分功能位点。结果表明,SLA-2bm属于一个新的等位基因,巴马小型猪是保留原始基因特征的品种。     

深化基因工程课程改革 提高教学质量

基因工程是生物工程专业的主干课程,必须以培养学生创新精神和实践能力为核心,重点培养学生综合素质和能力.为此,我们构建了理论和实践教学体系,优化课程教学内容,加强实践教学环节,充分运用现代化多媒体教学手段,加强网络课程建设,改进教学方法等为内容的教学改革.既注重传授学生专业知识,更注重传授学会"学习"的方法,旨在提高基因工程课堂教学质量,从而满足生物工程专业和21世纪人才培养要求.     

药物分子伴侣: 蛋白质折叠运输缺陷的新疗法

大量遗传性疾病的发生是由于基因突变引起蛋白质错误折叠而不能运输到作用位点,从而导致功能缺陷．近年来兴起的药物分子伴侣是恢复蛋白质折叠运输缺陷的新疗法,这类化合物一般为目的蛋白的底物类似物、受体配基或酶抑制剂等化学小分子,具细胞通透性,能在内质网中特异性识别并结合突变蛋白,校正并稳定其正确构象,协助其运输到正确位点,直接恢复突变蛋白功能,可治疗各种南蛋白质折叠运输缺陷导致的内分泌及代谢疾病．目前已报道的由药物分子伴侣恢复功能的突变蛋白主要为质膜蛋白及细胞器蛋白,如ATP结合盒转运蛋白、G-蛋白耦联受体及溶酶体酶等．大量的细胞及动物实验结果显示了药物分子伴侣的临床应用前景广阔,目前已有一例临床实验获得了成功．     

Characterization of heparan sulfate N-deacetylase/N-sulfotransferase isoform 4 using synthetic oligosaccharide substrates

Background

The final structure of heparan sulfate chains is strictly regulated in vivo, though the biosynthesis is not guided by a template process. N-deacetylase/N-sulfotransferase (NDST) is the first modification enzyme in the HS biosynthetic pathway. The N-sulfo groups introduced by NDST are reportedly involved in determination of the susceptibility to subsequent processes catalyzed by C₅-epimerse and 3-O-sulfotransferases. Understanding the substrate specificities of the four human NDST isoforms has become central to uncovering the regulatory mechanism of HS biosynthesis.