Oncogene-induced transformation of C3H 10T1/2 cells is enhanced by tumor promoters

The tumor promoters 12-O-tetradecanoyl-phorbol-13-acetate and teleocidin markedly enhanced the transformation of C3H 10T1/2 mouse fibroblasts when these cells were transfected with the cloned human bladder cancer c-rasH oncogene. Transfection studies with the drug resistance marker gpt and time course studies indicate that this enhancement is not simply an effect on the process of DNA transfection. These findings, together with parallel studies with NIH 3T3 fibroblasts, also indicate that the competence of animal cells for DNA transfection is a function of the recipient cell line, the transfected marker, and the growth conditions. Our findings suggest that during multistage carcinogenesis tumor promoters may complement the function of activated cellular oncogenes.     

Hydrophobicity of amino acid residues in globular proteins

During biosynthesis, a globular protein folds into a tight particle with an interior core that is shielded from the surrounding solvent. The hydrophobic effect is thought to play a key role in mediating this process: nonpolar residues expelled from water engender a molecular interior where they can be buried. Paradoxically, results of earlier quantitative analyses have suggested that the tendency for nonpolar residues to be buried within proteins is weak. However, such analyses merely classify residues as either "exposed" or "buried." In the experiment reported in this article proteins of known structure were used to measure the average area that each residue buries upon folding. This characteristic quantity, the average area buried, is correlated with residue hydrophobicity.     

Age-dependent changes in proteins of Drosophila melanogaster

Several molecular theories of aging postulate that there are age-dependent changes in gene expression and that these changes contribute to the reduction in the viability of senescent cells. High-resolution, semiautomated, quantitative two-dimensional gel electrophoresis of many soluble proteins was used to test this hypothesis in Drosophila. Two-dimensional protein gel patterns were analyzed for each of three age groups of [(35)S]methionine-labeled adult male Drosophila melanogaster, which, except for their spermatocytes, consist entirely of fixed postmitotic cells. Seven relatively abundant polypeptides expressed in middle-aged (28-day-old) flies were absent in both young(10-day-old) and old (44-day-old) flies. Quantitative analyses of an additional 100 polypeptides were carried out by computer-assisted microdensitometry of fluorograms of the gel preparations. These analyses revealed a significant age-related heterogeneity in the quantitative distribution of radiolabel in these proteins. The data indicate that the qualitative pattern of gene expression is identical in young and old flies, but that profound quantitative changes occur in the expression of proteins during the Drosophila life-span.     

几丁质酶基因rs10494132T/C多态性与支气管哮喘的相关性研究

目的研究几丁质酶基因位点rs10494132基因多态性与支气管哮喘发病的相关性。方法选择133例支气管哮喘患者和90例正常对照,利用双脱氧链终止法测序进行rs10494132位点基因多态性分析,测定两组人群嗜酸性粒细胞绝对值(EO#)、血清总IgE水平及FEV1%(FEV1%占预计值百分比)。结果两组等位基因T和C分布、以及TT和TC基因型分布差异均无统计学意义(P>0.05)。支气管哮喘组中,不同基因型EO#、血清总IgE水平及FEV1%比较差异有统计学意义(P<0.05或0.01)。同一基因型EO#、血清总IgE及FEV1%在两组间比较差异有统计学意义(P<0.05或0.01)。结论湛江人群中几丁质酶基因rs10494132T/C位点多态性与支气管哮喘无明显相关,但可能与哮喘表型有关。     

Limit of T cell tolerance to self proteins by peptide presentation

Cytotoxic T lymphocytes (CTLs) recognize foreign peptides bound to major histocompatibility complex (MHC) class I molecules. MHC molecules can also bind endogenous self peptides, to which T cells are tolerant. Normal mice contained CTLs specific for self peptides that were from proteins of ubiquitous or tissue-restricted expression. In vivo, these endogenous self peptides are not naturally presented in sufficient density by somatic cells expressing MHC class I molecules. They can, however, be presented if added exogenously. Thus, our data imply that CTLs are only tolerant of those endogenous self peptide sequences that are presented by MHC class I-positive cells in a physiological manner.     

马铃薯3个StSnRK2基因启动子的克隆与序列分析

【目的】克隆马铃薯StSnRK2.1、StSnRK2.2和StSnRK2.4基因的启动子片段,为马铃薯StSnRK2基因表达与功能研究奠定基础.【方法】以马铃薯(Solanum tuberosum L.)品种‘陇薯3号’为试材,采用PCR技术从马铃薯基因组DNA中分离得到了3个SnRK2基因启动子.通过PCR扩增,酶切鉴定,测序,利用PlantCARE和PLACE在线分析软件预测分析所得序列.【结果】获得与预期大小基本一致的目的片段,分别为StSnRK2.1基因启动子、StSnRK2.2基因启动子和StSnRK2.4基因启动子.分析软件预测分析表明,启动子调控序列中除含有典型的真核生物核心启动子外,还含有多个CAAT-box、TATA-box等启动子元件,以及相应的ABRE、DRE/CRT、LTRE等与激素应答、逆境胁迫相关的顺式作用元件.【结论】这些结果预示StSnRK2.1、StSnRK2.2和StSnRK2.4基因调控机制相对复杂,可能参与了ABA,干旱,盐等多种逆境胁迫信号的转导过程,在马铃薯逆境胁迫应答过程中具有重要的功能作用.     

Chromosomal effects of rapid gene evolution in Drosophila melanogaster

Rapid adaptive fixation of a new favorable mutation is expected to affect neighboring genes along the chromosome. Evolutionary theory predicts that the chromosomal region would show a reduced level of genetic variation and an excess of rare alleles. We have confirmed these predictions in a region of the X chromosome of Drosophila melanogaster that contains a newly evolved gene for a component of the sperm axoneme. In D. simulans, where the novel gene does not exist, the pattern of genetic variation is consistent with selection against recurrent deleterious mutations. These findings imply that the pattern of genetic variation along a chromosome may be useful for inferring its evolutionary history and for revealing regions in which recent adaptive fixations have taken place.     

Genes for beta chain of human T-cell antigen receptor map to regions of chromosomal rearrangement in T cells

The T-cell antigen receptor is a cell-surface molecule that participates in the immune response. In the present experiments the genes encoding the beta chain of the T-cell receptor were found to reside on the long arm of human chromosome 7 at or near band q32. Related sequences were found on the short arm of chromosome 7 in bands p15-21 in some experiments. Chromosomal rearrangements in T-cells from normal individuals and patients with ataxia telangiectasia have previously been observed at and near these map assignments for the beta-chain genes.     

Biosynthess of histones and acidic nuclear proteins under different conditions of growth

The incorporation of uniformly labeled L-lysine-C(14) into the normal and regenerating rat liver, into Novikoff hepatoma histones, and into acidic nuclear proteins was studied. In rat liver, different histone fractions incorporate labeled lysine to a different extent. Such differences become less obvious in regenerating liver, and they are even less so in Novikoff hepatoma. In the hepatoma cells the ratio of the biosynthesized acidic nuclear proteins to histones was altered.     

Dual role of the Drosophila pattern gene tailless in embryonic termini

One of the first zygotically active genes required for formation of the terminal domains of the Drosophila embryo is tailless (tll). Expression of the tll gene is activated ectopically in gain-of-function mutants of the maternal terminal gene torso (tor); this suggests that tor normally activates the tll gene in the termini. Ectopic expression of tll under the control of an inducible promoter results in differentiation of ectopic terminal-specific structures, the Filzk?rper, and leads to the activation of at least one gene, hunchback, that is required to form these structures. Ectopic expression of the tll gene also represses segmentation by repressing the gap genes Krüppel and knirps and probably also pair rule genes.     

低氧胁迫与常氧条件下斑马鱼鳃中热休克蛋白基因家族的表达差异比较

为研究斑马鱼热休克蛋白(HSP)应对低氧胁迫的生物学功能,对低氧胁迫与常氧条件下斑马鱼Danio rerio鳃组织进行转录组测序,利用实时荧光定量RT-PCR技术检测了低氧胁迫与常氧条件下斑马鱼鳃中热休克蛋白家族基因的表达差异。结果表明:在参与比较的斑马鱼鳃转录组测序中,共找到80个热休克蛋白家族基因成员;在低氧与常氧条件下鳃中热休克蛋白家族中有28个基因表达呈明显变化,其中16个基因表达量显著上调(P<0. 05),12个基因表达量显著下调(P<0. 05); Hsp47基因是低氧胁迫下表达量增加最明显的热休克蛋白基因,Hsp90ab1基因是低氧胁迫下唯一表达量升高的大分子热休克蛋白基因;低氧胁迫下Hsp47在鳃、肌肉中的表达极显著升高(P<0. 01),Hsp90ab1在鳃、皮肤和肌肉中的表达显著或极显著升高(P<0. 05或P<0. 01);不同低氧浓度胁迫下斑马鱼鳃中HSP47和HSP90ab1蛋白表达均呈现显著增加(P<0. 05)。研究表明,HSP47和HSP90ab1可能是斑马鱼低氧应激中最重要的热休克蛋白成员,具有重要的适应功能。     

Translocation of C. elegans CED-4 to nuclear membranes during programmed cell death

The Caenorhabditis elegans Bcl-2-like protein CED-9 prevents programmed cell death by antagonizing the Apaf-1-like cell-death activator CED-4. Endogenous CED-9 and CED-4 proteins localized to mitochondria in wild-type embryos, in which most cells survive. By contrast, in embryos in which cells had been induced to die, CED-4 assumed a perinuclear localization. CED-4 translocation induced by the cell-death activator EGL-1 was blocked by a gain-of-function mutation in ced-9 but was not dependent on ced-3 function, suggesting that CED-4 translocation precedes caspase activation and the execution phase of programmed cell death. Thus, a change in the subcellular localization of CED-4 may drive programmed cell death.     

白细胞介素13基因+1923C/T多态性与哮喘的相关性及对血浆总IgE水平的影响

目的 :探讨白细胞介素 1 3(IL- 1 3)基因内含子区 +1 92 3C/ T多态性与哮喘的相关性及对血浆总 Ig E水平的影响。方法 :用聚合酶链反应和限制性片段长度多态性 (PCR/ RFL P)方法检测哮喘与对照组 +1 92 3位点多态性 ,用酶联免疫吸附法 (EL ISA)测定血浆总 Ig E水平。结果 :+1 92 3位点等位基因 C、T频率在两组间分布的差异有显著性 (χ2 =9.30 ,P<0 .0 1 ) ,等位基因 T与哮喘关联 ,OR(T/ C) =1 .87,95 % CI=1 .2 5～ 2 .80 ,P<0 .0 1。两组基因型 (TT、CT、CC)频率的分布差异亦有显著意义 (χ2 =9.92 ,P<0 .0 1 ) ,同组内 ,T等位基因携带者血浆总 Ig E水平高于非携带者 ;同一基因型 ,哮喘组总 Ig E水平高于对照组。结论 :IL- 1 3基因 +1 92 3位点多态性是影响哮喘的重要候选基因 ,T等位基因与哮喘关联 ,并可能通过增强 IL- 1 3基因的表达影响血浆总 Ig E水平     

Expression and function of the segmentation gene fushi tarazu during Drosophila neurogenesis

Segmentation genes control cell identities during early pattern formation in Drosophila. One of these genes, fushi tarazu (ftz), is now shown also to control cell fate during neurogenesis. Early in development, ftz is expressed in a striped pattern at the blastoderm stage. Later, it is transiently expressed in a specific subset of neuronal precursor cells, neurons (such as aCC, pCC, RP1, and RP2), and glia in the developing central nervous system (CNS). The function of ftz in the CNS was determined by creating ftz mutant embryos that express ftz in the blastoderm stripes but not in the CNS. In the absence of ftz CNS expression, some neurons appear normal (for example, the aCC, pCC, and RP1), whereas the RP2 neuron extends its growth cone along an abnormal pathway, mimicking its sibling (RP1), suggesting a transformation in neuronal identity.     

植物青枯菌相关基因的克隆及致病力测定分析

以PM2644为受菌体，通过基因功能互补的方法，将从野生青枯菌基因文库中筛选得到的克隆进一步克隆得到克隆pLTK15。胞外酶活性测定结果表明，pLTK15与突变株PM2644接合产生的接合子能完全恢复突变株PM2644聚半乳糖醛酸酶的活性，接合子上清液SDS－PAGE电泳结果表明，接合子只能互补PM2644缺失的62．5kDa的一种胞外蛋白，经致病力测定，pLTDK15能使突变株PM2644的致病力得到部分恢复。结果表明，聚半乳糖醛酸酶和62．5kDa的胞外蛋白在青枯菌的致病过程中起着一定的作用。