多巴胺D4受体基因exon Ⅲ 48bp VNTR多态性与学龄儿童气质的相关性

目的 了解多巴胺D4受体基因（DRD4）第3外显子48bp可变串联重复序列多态性（exon Ⅲ 48bp VNTR）与学龄儿童气质的相关性。方法 随机整群抽取350名8~12岁健康儿童进行问卷调查,其中一半儿童进行口腔上皮采集,其中164名儿童问卷资料完整且口腔上皮细胞中DNA浓度较高的样本纳入研究,运用PCR技术进行DRD4 exon Ⅲ 48bp VNTR分型,并分析该基因及其与环境的交互作用对气质的影响。结果 携带L-DRD4基因型儿童在活动水平、反应强度、情绪本质以及坚持性4个维度的得分均低于S-DRD4基因型儿童（P < 0.05）。母亲教养方式为拒绝/否认（OR=2.281,P < 0.05）、儿童性别（OR=2.766,P < 0.05）的主效应及儿童性别与DRD4 exon Ⅲ 48bp VNTR的交互作用对儿童活动水平有影响（OR=0.582,P < 0.05）。DRD4 exon Ⅲ 48bp VNTR主效应（OR=0.314,P < 0.01）及该基因与母亲教养方式为拒绝/否认的交互作用（OR=1.872,P < 0.01）对儿童反应强度有影响。DRD4 exon Ⅲ 48bp VNTR （OR=0.420,P < 0.05）及母亲教养方式为拒绝/否认（OR=2.236,P < 0.05）的主效应对儿童坚持性有影响。结论 DRD4 exon Ⅲ 48bp VNTR及该基因与其他因素的交互作用可能影响学龄儿童的活动水平和反应强度。     

Array comparative genomic hybridization (aCGH) reveals the largest novel deletion in PCCA found in a Saudi family with propionic acidemia

Propionic acidemia is a metabolic disorder (OMIM 606054) caused by deficiency of the propionyl-coenzyme A (CoA) carboxylase, which subsequently results in accumulation of propionic acid. Patients may initially present with poor feeding, vomiting, loss of appetite, hypotonia, and lethargy. Later, most children will show different degrees of motor, social and language delay even more serious medical problems, including heart abnormalities, seizures, coma, and possibly death. Two siblings affected with propionic acidemia were screened for putative mutations in PCCA and PCCB genes coding α and β subunits of propionyl-coenzyme A (CoA) carboxylase, respectively. Both patients had a mild–severe form of propionic acidemia. The investigations using PCR, long-PCR, array comparative genomic hybridization (aCGH), and sequencing techniques showed a 73 kb deletion extending from intron 16 to intron 19 and an 18 bp insertion at the distal end of the deletion in PCCA gene. The deletion so far is the largest gross change reported in the literature for the PCCA gene.     

mtDNA4977bp缺失分析评价肿瘤细胞辐射敏感性的研究

目的 探讨mtDNA4977bp缺失用于肿瘤细胞辐射敏感性检测的可行性。方法 选取三种不同肿瘤细胞株:肝癌细胞(HepG₂)、食管癌细胞(EC-9706)和乳腺癌细胞(MCF-7)。采用MTT法检测肿瘤细胞经γ射线照射后的存活分数(SF);巢式PCR法检测肿瘤细胞的mtDNA4977bp缺失率。结果 MTT法:2Gy、4Gy和8Gy照射后,HepG₂和EC-9706的SF显著低于MCF-7,表明HepG₂和EC-9706细胞具有更高的辐射敏感性。PCR法:1Gy和4Gy照射后3种肿瘤细胞mtDNA4977bp缺失率差异无统计学意义,8Gy照射后HepG₂和EC-9706mtDNA4977bp缺失进一步增加,而MCF-7的缺失率下降,显著低于HepG₂与EC-9706细胞的缺失率,提示HepG₂和EC-9706细胞的辐射敏感性高于MCF-7细胞。结论 mtDNA4977bp缺失作为新的生物学指标,有希望更加客观准确地评价肿瘤细胞的辐射敏感性。     

Trypanosomes of subgenus Trypanozoon are diploid for housekeeping genes

The ploidy of trypanosomes has until now remained undetermined, although isoenzyme studies and direct measurements of DNA content and complexity suggest diploidy. Direct cytogenetic analysis is not possible, because the chromosomes do not condense at any stage of the cell cycle. We now present evidence from analysis of restriction site polymorphisms in and around three glycolytic enzyme genes (phosphoglycerate kinase, triosephosphate isomerase, glyceraldehyde phosphate dehydrogenase) and the tubulin gene cluster, that trypanosomes of subgenus Trypanozoon are diploid for these housekeeping genes. This result is still compatible with the single copy nature of variant surface glycoprotein (VSG) genes in Trypanozoon, if different VSG genes are present in corresponding positions on paired chromosomes. Using pulse field gradient gel electrophoresis, we show that the genes for the three glycolytic enzymes are all located in very large DNA molecules, but the gene for triosephosphate isomerase is in another fraction from the genes for the other two enzymes. Since all three enzymes are located in glycosomes, which are trypanosome microbodies, the genes for glycosomal enzymes are not all clustered in one chromosomal segment of the trypanosome genome.     

一个含有25 bp内含子的阴道毛滴虫Rab1-like新基因

目的 克隆和鉴定一个新的阴道毛滴虫Rab1-like基因(TvRab1-like)及其内含子.方法 我们从一阴道毛滴虫cDNA表达文库中分离出一个cDNA克隆,它与各物种的Rab家族蛋白有较高的同源性,因此我们进一步用BLASTP、RPS-BLAST、ClustalW和MEGA3等分析软件对该cDNA克隆进行了序列分析和进化树分析;用PCR和RT-PCR等技术分别对该基因组和mRNA进行了扩增和测序分析.结果 序列分析结果表明该cDNA克隆长705 bp,开放阅读框具603 bp,推测肽链含有200个氨基酸.序列比较分析结果提示该cDNA克隆所推测的蛋白质是一个Rab1亚家族的亚型.进化树分析也表明它属于阴道毛滴虫Rab1亚家族.基因组PCR扩增和测序分析表明该基因包含一个25 bp的内含子,该内含子具有阴道毛滴虫和其它真核生物较大内含子所具备的典型的5'GT-AG-3'和分支位点基序.RT-PCR产物及其测序分析表明在该基因的转录本中存在着未剪切和剪切后的mRNA,说明确实有内含子的存在.结论 TvRab1-like基因属于阴道毛滴虫Rab1亚家族,该基因含有一个25 bp的内含子.该内含子是至今发现的最小的阴道毛滴虫基因内含子之一,很可能也是真核生物中最小的内含子.对诸类最低等真核生物内含子的研究将有助于我们理解真核生物内含子的起源和进化.     

Molecular determination of T-cell receptor alpha and beta chain genotypes in human families

Polymorphism in genes encoding the alpha and beta chain of the human T cell receptor has been detected by Southern blot analysis. Genomic DNA samples were isolated from B lymphoblastoid cell lines derived from members of families, each family including at least one individual with a recombinant HLA haplotype. T cell receptor alpha and beta chain haplotypes could be assigned in the families on the basis of observed restriction fragment length polymorphism (RFLP). Polymorphism in the alpha chain gene was detected in BglII digests using an alpha chain probe that included the V, J, C, and 3' untranslated sequences. A probe consisting of only the constant region (C alpha) revealed no polymorphism indicating that the polymorphic fragment hybridized to V, J, or 3' untranslated sequences of the alpha chain. Polymorphism in beta chain genes was observed in BglII digested DNA samples using a probe that corresponds to the constant region (C beta). Polymorphic C beta restriction fragments of 10.0 and 9.2 kilobase segregated in six of the eight families studied. Recent structural data for the C beta region suggest that the polymorphic BglII site lies in the region 5' to the C beta 2 gene. These polymorphisms should serve as markers for alpha and beta chain complexes allowing genetic studies of these immunologically important gene families.     

Organization, sequence and expression of the HLA-B27 gene: a molecular approach to analyze HLA and disease associations

Among the numerous autoimmune diseases associated with various HLA alleles, the one with the highest relative risk so far reported has been ankylosing spondylitis with HLA-B27. To examine this relationship more directly, we have cloned the gene encoding the HLA-B27 antigen and determined its complete DNA sequence. Comparison of the HLA-B27 sequence with that of the allelic HLA-B27 shows a high level of homology. Mutations are distributed evenly between exons and introns. Exon 1 and intron 1 are the most divergent ones, and the degree of divergence distinctly declines towards the 3' end. The HLA-B57 gene when transfected into murine L cells is expressed on the cell surface and reacts with a panel of monoclonal antibodies directed against monomorphic and polymorphic determinants associated with HLA-B27 antigen. The isolation of this gene allows for the first time a search for structural features which make the HLA-B27 antigen a high risk genetic factor for a group of rheumatoid disorders, in particular ankylosing spondylitis.