数学解译核酸多样性

以离散数学理论和方法与生命科学原理，讨论mRNA的转录和DNA的复制及其基因信息的传输这一异常复杂的高序化特异反应过程。其信息符号(mRNA：U、C、A、G，DNA：T、C、A、G)对基因信息的传入与传出、保留与变异起着最主要的作用。例证核苷酸、脱氧核苷酸的4种信息符号的排序变化是mRNA、DNA分子结构多样性的基本原因，尤其DNA模板链上的4种信息符号排序变化是自然界生命现象复杂多样的最根本原因。     

用AFM观察小白鼠心肌核DNA片段的基因体外表达和垃圾DNA的相互作用

用AFM直接现场观察、体外表达等实验技术组合,观察到小白鼠（Balb/c）心肌核DNA片段的基因在体外表达过程中形成的n mRNA（n=9）线型链状复合体,处于垃圾DNA片段的特定的“翻译平台”上,其每种mRNA两端非共价键分别结合自己编码蛋白质（即分子开关）,中间的编码序列均非共价结合完全可解离的翻译活性因子等多种蛋白质：这些蛋白质可能均由垃圾DNA片段的极复杂的立体结构所形成的、匹配协同的、专一性蛋白质通路所调控,该通路对蛋白质按顺序分别进行特异性双向调控.核内n mRNA线型链状复合体在体外可翻译出LDH等蛋白质,并显示n mRNA翻译的“群体效应”.用AFM还观察到胞质制取的n mRNA（n=12）线型链状复合体（无垃圾DNA存在）,体外翻译出少量LDH等蛋白质,并显示n mRNA翻译的＂群体效应＂.本工作展示了未来运用AFM观察体外表达等生物学反应,研究基因表达与调控机制及其与垃圾DNA相互作用的前景.     

不同物种间胰岛素及其编码mRNA,DNA序列比较与分析

通过PSI-BLAST搜索与人类胰岛素原(含有86个氨基酸)相似的蛋白质序列，并进行比对，计算比对矩阵的相似得分和期望值，同时运用ClustalW算法对不同物种编码前胰岛素原mRNA及其翻译的蛋白质和DNA序列进行多重比对．结果发现，脊椎动物的胰岛素蛋白质一级结构(A链和B链)和mRNA非常相似，但部分动物C肽的部分序列有差异；系统进化分析表明，人和猴、小鼠和大鼠编码胰岛素的mRNA在进化上关系相近．各物种间编码相同氨基酸的核苷酸序列（CDS)相同，但编码胰岛素的DNA序列不同．各物种胰岛素原蛋白质序列中，A链和B链序列保守，C肽有一定的差异；DNA序列差异较大．     

Observation and Analysis of in vitro Expression of Mouse Heart Nuclear DNA Fragments by AFM

Using AFM,we observed linear chain-like complexes formed by some specific proteins and the multi-mRNAs during the in vitro expression of some active genes on the DNA fragments. The LDH mRNA in the multi-mRNA complex can in vitro translate LDH. Via AFM, we also discovered that nmRNA prepared from heart muscles, along with some specific proteins can form linear chain-like nmRNA complexes in which LDH mRNA can also translate LDH in vitro. Our work shows the prospective application of AFM in the research of the biological reaction of the active genes on the DNA fragments.     

AFM观察小鼠心肌核DNA片段的基因组合形成"基因系"的系统性和垃圾DNA的相互作用

用原子力显微镜(AFM)直接观察、小白鼠心肌等组织的核DNA片段的基因体外转录等多种实验技术组合,通过AFM观察到心肌核DNA片段上的基因,处于垃圾DNA的“转录平台”上,在体外转录过程中,由n(n=3、4等)个活性基因节,对应的n-1个“基因间隔”,依特定的排列组合分别形成n(n=3、4等)种大小不同的“基因系”,各“基因系”中的基因节同时转录,分别形成对应nRNA(n=9、12等)链状复合体,nRMA链状复合体分别与对应基因系的单链DNA两边的“接口”相联。核内对应nmRNA数量减少,形成负反馈效应后,使nRNA从对应“基因系”上迅速解离下来,核内经“转录后修饰”形成对应nmRNA链状复合体。该复合体主要在核内,处于垃圾DNA的“翻译平台”上进行蛋白质翻译,并在核内加工修饰形成有活性蛋白质。本工作展示了未来运用AFM观察生物学反应、研究核基因转录与调控的分子机理、基因组合形成基因系的系统性和垃圾DNA的相互作用的前景。     

DNA polymerase beta overexpression correlates with poor prognosis in esophageal cancer patients

Gene of DNA polymerase beta (pol ) plays an important role in base excision repair, DNA replication and translesion synthesis. This study aims to investigate the expression and prognostic significance of DNA pol in esophageal cancer. DNA pol expression was analyzed using real-time quantitative PCR (RT-qPCR) and immunohistochemical staining on tissue samples from a consecutive series of 114 esophageal squamous carcinoma patients who underwent resections between 2002 and 2006. Pol expression was investigated on its correlation to clinico-pathological factors and survival. RT-qPCR results showed higher expression of DNA pol mRNA in tumor tissue than in its matched adjacent non-tumor tissue sample, different expression of DNA pol mRNA was noticed with significance between tumors with and without lymph node metastasis. Immunohistochemistry staining results indicated the pol strong-positive rate was 44.73% (51/114) in tumor tissue samples and 0.00% in matched adjacent non-tumor tissue samples, with significant difference. Kaplan-Meier survival curves revealed that high expression of pol was associated with tumor metastasis and poor prognosis in esophageal cancer patients. Our data suggests that pol plays an important role in tumor progression and that high pol expression predicts an unfavorable prognosis in esophageal squamous carcinoma patients.     

Identification of scrapie prion protein-specific mRNA in scrapie-infected and uninfected brain

To date no nucleic acid has been found in the purified infectious agent which causes the spongiform encephalopathy known as scrapie. In an attempt to identify a unique scrapie virus-associated messenger RNA in tissues of infected animals, we have synthesized an oligonucleotide probe complementary to the mRNA sequence corresponding to the amino-acid sequence of the prion protein, PrP27-30 (ref. 1). We report here that, with this probe, a complementary DNA clone representing PrP27-30 was obtained from scrapie-infected mouse brain; the DNA sequence of this clone could be translated into a protein that matches exactly the published sequence of PrP27-30. The cDNA clone hybridized to a single 2.4-2.5-kilobase (kb) mRNA from both normal and scrapie-infected brain. Thus, the PrP27-30 mRNA is not uniquely associated with scrapie infectivity, suggesting that PrP27-30 may be a normal component of mouse and hamster brain.     

Nucleotide sequence of cloned cDNA of human c-myc oncogene

Like other transforming genes of retroviruses, the v-myc gene of the avian virus, MC29, has a homologue in the genome of normal eukaryotic cells. The human cellular homologue, c-myc, located on human chromosome 8, region q24 leads to qter (refs 1, 2), is translocated into the immunoglobulin heavy-chain locus on human chromosome 14 (ref. 3) in Burkitt's lymphoma, suggesting that c-myc has a primary role in transformation of some human haematopoietic cells. In addition, c-myc is amplified in the human promyelocytic leukaemia cell line, HL60 (refs 6, 7) which also contains high levels of c-myc mRNA. Recently, Colby et al. reported the nucleotide sequence of the human c-myc DNA isolated from a genomic recombinant DNA library derived from human fetal liver. This 4,053-base pair (bp) sequence includes two exons and one intron of the myc gene, and the authors have suggested the existence of a human c-myc mRNA of 2,291 nucleotides that has a coding capacity for a protein of molecular weight (Mr) 48,812. We have approached the problem of accurately defining the characteristics of the human c-myc mRNA and c-myc protein by determining the sequence of the c-myc cDNA isolated from a cDNA library prepared from mRNA of a clone of the K562 human leukaemic cell line. K562 cells are known to contain c-myc mRNA which is similar in size to the c-myc mRNA of other human cell types. We report here the sequence of 2,121 nucleotides of a human c-myc mRNA and demonstrate that its 5' noncoding sequence does not correspond to the sequence of the reported genomic human sequence. However, our data confirm that the intact human c-myc mRNA can encode a 48,812-Mr protein with a sequence identical to that reported by Colby et al.     

Influence of DNA methylation on transgene expression

DNA methylation plays an important role in gene expression in eukaryote. But DNA methylation of transgene usually leads to target gene silencing in plant genetic engineering. In this research, reporter gene b-glu- curonidase (GUS) gene ( uidA ) was introduced into tobaccos via Agrobacterium-mediated transformation method, and the foreign uidA gene became inactive in some transgenic tobaccos. No mRNA of uidA was detected in these plants by Northern blotting analysis, and DNA methylation of promoter region was found. The results indicated that gene silencing might be caused by DNA methylation of promoter.     

Characterization of the human factor VIII gene

The complete 186,000 base-pair (bp) human factor VIII gene has been isolated and consists of 26 exons ranging in size from 69 to 3,106 bp and introns as large as 32.4 kilobases (kb). Nine kb of mRNA and protein-coding DNA has been sequenced and the mRNA termini have been mapped. The relationship between internal duplications in factor VIII and evolution of the gene is discussed.     

含有重组人白细胞介素18基因的工程菌的产物表达和鉴定

0引言 1996年,Ushio等[1]从人的肝脏细胞中克隆了人的白细胞介素18(IL-18) cDNA,并在大肠杆菌中得到了表达.IL-18是国际上最新获得的细胞因子[2].     

Competence to replicate in the unfertilized egg is conferred by Cdc6 during meiotic maturation

Meiotic maturation, the final step of oogenesis, is a crucial stage of development in which an immature oocyte becomes a fertilizable egg. In Xenopus, the ability to replicate DNA is acquired during maturation at breakdown of the nuclear envelope by translation of a DNA synthesis inducer that is not present in the oocyte. Here we identify Cdc6, which is essential for recruiting the minichromosome maintenance (MCM) helicase to the pre-replication complex, as this inducer of DNA synthesis. We show that maternal cdc6 mRNA but not protein is stored in the oocyte. Cdc6 protein is synthesized during maturation, but this process can be blocked by degrading the maternal cdc6 mRNA by oligonucleotide antisense injections or by translation inhibition. Rescue experiments using recombinant Cdc6 protein show that Cdc6 is the only missing replication factor whose translation is necessary and sufficient to confer DNA replication competence to the egg before fertilization. The licence to replicate is given by Cdc6 at the end of meiosis I, but the cytostatic factor (CSF) pathway, which maintains large amounts of active Cdc2/Cyclin B2, prevents the entry into S phase until fertilization.     

黑曲霉β-葡萄糖苷酶基因的分离

以黑曲霉基因组DNA、mRNA为模板,利用种属相似性设计了一对引物,采用PCR与RT-PCR技术得到β-葡萄糖苷酶基因的DNA和cDNA全序列.测序表明:克隆得到的DNA序列全长2 924 bp,cDNA序列全长2 583 bp,编码860个氨基酸.编码序列推导的蛋白质序列相似性分析显示:完整蛋白质序列同源性高达97%～99%.该研究为β-葡萄糖苷酶基因的遗传转化及应用 奠定了基础.     

Expression and regulation of orphan receptor TR2 mRNA in germ cells of cryptorchid testis in rat and rhesus monkey

Expression and cellular localization of orphan receptor TR2 mRNA in relation to germ cell apoptosis in cryptorchid testes of rat and rhesus monkey have been studied by usingin situ hybridization andin situ 3′-end labeling of DNA fragments (TUNEL). The results show that: (i) TR2 mRNA is specifically expressed in the germ cells, mainly in the spermatocytes, round and elongated spermatids. The expression level of TR2 mRNA varies with the seminiferous cycle, (ii) In the rat cryptorchid testes on days 3 and 5 after the surgery, the germ cells began to undergo apoptosis with no evident decrease in TR2 mRNA level. On day 7.5, however, most germ cells underwent apoptosis, while the expression level of TR2 mRNA declined markedly, and TR2 mRNA was rarely expressed on day 10 thereafter, (iii) On days 15 and 20 of the cryptorchid testes of rhesus monkey, TR2 mRNA was only expressed in a few of primary spermatocytes and the mRNA was almost undetectable on days 30, 45, 60. These results suggest that TR2 mRNA probably plays an important role in spermatogenesis and germ cell apoptosis.     

ZNF382多克隆抗体的制备及其在蛋白质水平的表达研究

在筛选心脏发育相关新基因的研究时,本人克隆出了在人类心脏组织特异表达的基因-ZNF382,ZNF382在mRNA水平上的表达情况已经报道,为了阐明该基因在蛋白质水平的表达情况,本研究用质粒DNA注射小鼠法,生产制备得到抗ZNF382蛋白的多克隆抗体,胚胎原位抗体染色结果初步显示ZNF382蛋白主要在心脏和骨骼肌表达,其蛋白质表达水平与mRNA的表达水平基本一致,进一步表明该基因很可能参与心脏的形成或对心脏功能的发挥起重要作用.     

Histone genes are clustered with a 15-kilobase repeat in the chicken genome.

Histone mRNA isolated from 5-day-old chick embryos has been used as a template for complementary DNA (cDNA) synthesis. The resultant cDNA, after removal of sequences complementary to rRNA, was used to detect histone genes in adult chicken genomal DNA. Hybridisation data indicate that the histone genes are repeated about 10-fold in the chicken genome. Restriction endonuclease analysis reveals some sequence heterogeneity in these genes. However, the results show that chicken histone genes are clustered with a basic repeat unit of 15 kilobases.     

真核细胞转录的分子机理——2006年诺贝尔化学奖述评

2006年度诺贝尔化学奖授予了美国斯坦福大学医学院的结构生物学教授科恩伯格,表彰他在研究真核细胞转录分子机理方面的贡献.科恩伯格在真核细胞转录调节控制分子机制方面的研究中取得了突破性进展.他将现代生物化学技术和结构测定结合起来,在原子水平重建酵母RNA聚合酶以及一系列和模板DNA、产物mRNA、底物核酸、调节蛋白功能有关的复合物,从而使真核细胞转录的机理得到全面、深刻而清晰的阐述.