共查询到20条相似文献，搜索用时 15 毫秒
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Percec I Plenge RM Nadeau JH Bartolomei MS Willard HF 《Science (New York, N.Y.)》2002,296(5570):1136-1139
X chromosome inactivation is the silencing mechanism eutherian mammals use to equalize the expression of X-linked genes between males and females early in embryonic development. In the mouse, genetic control of inactivation requires elements within the X inactivation center (Xic) on the X chromosome that influence the choice of which X chromosome is to be inactivated in individual cells. It has long been posited that unidentified autosomal factors are essential to the process. We have used chemical mutagenesis in the mouse to identify specific factors involved in X inactivation and report two genetically distinct autosomal mutations with dominant effects on X chromosome choice early in embryogenesis. 相似文献
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Identification of the protein encoded by the E6 transforming gene of bovine papillomavirus 总被引：36，自引：0，他引：36
Papillomaviruses (PV) contain several conserved genes that may encode nonstructural proteins; however, none of these predicted gene products have been identified. Papillomavirus E6 genes are retained and expressed as RNA in PV-associated human and animal carcinomas and cell lines. This suggests that the E6 gene product may be important in the maintenance of the malignant phenotype. The E6 open reading frame of the bovine papillomavirus (BPV) genome has been identified as one of two BPV genes that can independently transform mouse cells in vitro. A polypeptide encoded by this region of BPV was produced in a bacterial expression vector and used to raise antisera. The antisera specifically immunoprecipitated the predicted 15.5-kilodalton BPV E6 protein from cells transformed by the E6 gene. The E6 protein was identified in both the nuclear and membrane fractions of these transformed cells. 相似文献
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A comparison of whole-genome shotgun-derived mouse chromosome 16 and the human genome 总被引：1，自引：0，他引：1
Mural RJ Adams MD Myers EW Smith HO Miklos GL Wides R Halpern A Li PW Sutton GG Nadeau J Salzberg SL Holt RA Kodira CD Lu F Chen L Deng Z Evangelista CC Gan W Heiman TJ Li J Li Z Merkulov GV Milshina NV Naik AK Qi R Shue BC Wang A Wang J Wang X Yan X Ye J Yooseph S Zhao Q Zheng L Zhu SC Biddick K Bolanos R Delcher AL Dew IM Fasulo D Flanigan MJ Huson DH Kravitz SA Miller JR Mobarry CM Reinert K Remington KA Zhang Q Zheng XH Nusskern DR Lai Z Lei Y Zhong W Yao A Guan P Ji RR Gu Z Wang ZY Zhong F 《Science (New York, N.Y.)》2002,296(5573):1661-1671
The high degree of similarity between the mouse and human genomes is demonstrated through analysis of the sequence of mouse chromosome 16 (Mmu 16), which was obtained as part of a whole-genome shotgun assembly of the mouse genome. The mouse genome is about 10% smaller than the human genome, owing to a lower repetitive DNA content. Comparison of the structure and protein-coding potential of Mmu 16 with that of the homologous segments of the human genome identifies regions of conserved synteny with human chromosomes (Hsa) 3, 8, 12, 16, 21, and 22. Gene content and order are highly conserved between Mmu 16 and the syntenic blocks of the human genome. Of the 731 predicted genes on Mmu 16, 509 align with orthologs on the corresponding portions of the human genome, 44 are likely paralogous to these genes, and 164 genes have homologs elsewhere in the human genome; there are 14 genes for which we could find no human counterpart. 相似文献
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【目的】研究腹腔注射亚精胺对鼠卵巢组织多胺代谢的影响。【方法】给鼠腹腔注射不同剂量亚精胺[0(对照组、0.05、0.10和0.15 mg·g~(-1)],应用实时荧光定量PCR检测多胺代谢关键基因表达量,应用高效液相色谱检测鼠卵巢组织中多胺含量。【结果】注射0.15 mg·g~(-1)亚精胺时,卵巢组织ODC、OAZ1、SPMS、SSAT、PAOX和SMOX基因表达量显著高于其他3组;注射亚精胺组鼠卵巢组织SPDS表达量均显著低于对照组;注射0.10 mg·g-1亚精胺组鼠卵巢组织中腐胺和亚精胺含量均显著高于对照组,而注射亚精胺对卵巢中精胺含量无显著影响。【结论】外源性亚精胺的腹腔注射可导致鼠卵巢组织中多胺含量以及多胺代谢相关基因表达量发生变化,且具有剂量依赖性,提示外源性亚精胺可通过介导卵巢组织的多胺代谢来参与调控卵巢功能。 相似文献
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Targeting of nonexpressed genes in embryonic stem cells via homologous recombination 总被引：18，自引：0，他引：18
R S Johnson M Sheng M E Greenberg R D Kolodner V E Papaioannou B M Spiegelman 《Science (New York, N.Y.)》1989,245(4923):1234-1236
Gene targeting via homologous recombination-mediated disruption in murine embryonic stem (ES) cells has been described for a number of different genes expressed in these cells; it has not been reported for any nonexpressed genes. Pluripotent stem cell lines were isolated with homologously recombined insertions at three different loci: c-fos, which is expressed at a low level in ES cells, and two genes, adipsin and adipocyte P2 (aP2), which are transcribed specifically in adipose cells and are not expressed at detectable levels in ES cells. The frequencies at which homologous recombination events occurred did not correlate with levels of expression of the targeted genes, but did occur at rates comparable to those previously reported for genes that are actively expressed in ES cells. Injection of successfully targeted cells into mouse blastocysts resulted in the formation of chimeric mice. These studies demonstrate the feasibility of altering genes in ES cells that are expressed in a tissue-specific manner in the mouse, in order to study their function at later developmental stages. 相似文献
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The action of oncogenes in the cytoplasm and nucleus 总被引：69，自引：0，他引：69
R A Weinberg 《Science (New York, N.Y.)》1985,230(4727):770-776
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SONG Li NING Yi-bao ZHANG Qi-jing YANG Cheng-huai GAO Guang HAN Jian-feng 《中国农业科学(英文版)》2008,7(5):636-640
Increasing antimicrobial resistance （AR） has become a severe problem of public health in the world, whereas control of the AR of bacteria will be based on investigation of the AR mechanism. Furthermore, understanding the existent selectivity of AR organisms from animals can prevent the emergence and diffusion of AR effectively. PCR amplifications of gyrA and parC genes have been performed for detecting fluoroquinolones-resistance （FR） genes. A conjugational transfer test has been carried out using a donor which is resistant to tetracycline （TE）, ampicillin （AMP）, sulfamethoxazole-trimethoprim （SXT）, and a recipient which is sensitive to TE, AMP, and SXT. The AR strains have been passed 20 passages. Two groups of chicken inoculated multi-AR Escherichia coli （E. coli） and multi-AR Salmonella, respectively, are mix-fed. The result shows that amino acid codons of Ser-83 and Asp-87 are mutations from gyrA and there are no mutations from parC genes in all the FR strains. Resistance to TE, AM, and SXT can transfer among E. coli and the conjugal transfer frequency of TE is 3×10^-7. AR can inherit in 20 passages at least. The multi-AR E. coli and Salmonella can be isolated from all chickens three days after inoculation but CIP-resistant strains decrease during the time run out and disappear at 23 days after inoculation. The results indicate that the mutations of gene gyrA are correlative with the FR phenotype. AR genes that are not connected to the chromosome can transfer horizontally and vertically. AR bacteria can diffuse quickly and eliminate naturally from the host if the chicken is not under the pressure of this antibiotic. 相似文献
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毛色是家畜驯化过程中最早被选择的性状之一,对该性状的偏好性选择导致家畜毛色丰富多样。家畜的毛色表型是由黑素细胞中真黑色素（产生黑色 / 棕色）和褐黑色素（产生黄色 / 红色）的相对含量决定,当真黑色素或褐黑色素的合成被稀释,或者两种色素的合成均被稀释时,就会形成不同的稀释毛色表型。为深入理解家畜毛色变异的遗传机制,许多学者已经进行了大量的毛色遗传学研究,以确定家畜的毛色相关基因和因果突变。目前,已鉴定出超过 300 个基因座和 150 个与毛色相关的基因。稀释毛色表型作为动物毛色遗传研究领域的一个重要研究方向,其遗传学研究已取得了一定进展。已发现多个因果基因可以引起哺乳动物的毛色稀释和禽类的羽色稀释,这些基因通过影响潜在的色素形成途径来影响黑素细胞的发育和分化、黑色素的合成以及黑素小体的运输。相似的毛色稀释表型通常在不同物种间被发现,可能由保守的或不同的毛色稀释基因引起。在同一物种中,可能有多个基因导致相同或相似的稀释毛色表型。该文对农业经济动物（主要是猪、马、牛、羊、鸡）稀释毛色（羽色）表型的类型及其形成的因果基因和突变,以及遗传机理等研究进展进行综述,以期为动物稀释毛色（羽色）遗传机制的深入研究提供参考。 相似文献
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Tissue-specific and ectopic expression of genes introduced into transgenic mice by retroviruses 总被引：12，自引：0，他引：12
Recombinant retroviruses containing the complete genomic human beta globin gene (under the control of its own promoter) and the bacterial neomycin phosphotransferase gene (under the control of the normal or enhancerless viral promoter) were used to derive transgenic mouse strains by infection of preimplantation embryos. Expression of the beta globin gene in hematopoietic tissues was observed in all transgenic strains. In addition, one strain showed ectopic expression of beta globin in the same tissues that also expressed high levels of RNA from the viral promoter. It is likely that expression from the long terminal repeat (LTR), in contrast to expression from the internal promoter, is dependent on the site of integration. Thus, retroviral vectors can be used for tissue-specific expression of foreign genes in transgenic mice, as well as for the identification of loci that allow developmental activation of a provirus. 相似文献
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K G Chandy C B Williams R H Spencer B A Aguilar S Ghanshani B L Tempel G A Gutman 《Science (New York, N.Y.)》1990,247(4945):973-975
To understand the molecular mechanisms responsible for generating physiologically diverse potassium channels in mammalian cells, mouse genomic clones have been isolated with a potassium channel complementary DNA, MBK1, that is homologous to the Drosophila potassium channel gene, Shaker. A family of three closely related potassium channel genes (MK1, MK2, and MK3) that are encoded at distinct genomic loci has been isolated. Sequence analysis reveals that the coding region of each of these three genes exists as a single uninterrupted exon in the mouse genome. This organization precludes the generation of multiple forms of the protein by alternative RNA splicing, a mechanism known to characterize the Drosophila potassium channel genes Shaker and Shab. Thus, mammals may use a different strategy for generating diverse K+ channels by encoding related genes at multiple distinct genomic loci, each of which produces only a single protein. 相似文献
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Chromosomal locations of the murine T-cell receptor alpha-chain gene and the T-cell gamma gene 总被引：11，自引：0，他引：11
D M Kranz H Saito C M Disteche K Swisshelm D Pravtcheva F H Ruddle H N Eisen S Tonegawa 《Science (New York, N.Y.)》1985,227(4689):941-945
Two independent methods were used to identify the mouse chromosomes on which are located two families of immunoglobulin (Ig)-like genes that are rearranged and expressed in T lymphocytes. The genes coding for the alpha subunit of T-cell receptors are on chromosome 14 and the gamma genes, whose function is yet to be determined, are on chromosome 13. Since genes for the T-cell receptor beta chain were previously shown to be on mouse chromosome 6, all three of the Ig-like multigene families expressed and rearranged in T cells are located on different chromosomes, just as are the B-cell multigene families for the Ig heavy chain, and the Ig kappa and lambda light chains. The findings do not support earlier contentions that genes for T-cell receptors are linked to the Ig heavy chain locus (mouse chromosome 12) or to the major histocompatibility complex (mouse chromosome 17). 相似文献
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Bacterial differentiation 总被引：27，自引：0，他引：27
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部分云南粳稻品种的抗瘟性分类 总被引：11，自引：3，他引：11
根据云南部分粳稻品种对7个菌系的反应型，将596个粳稻品种划分为35群。借助单基因鉴别品种，推断了50个品种的基因型。应用致病谱广的北方小种，筛选出一批新抗源，满足抗病育种对抗源的需求，也为系统的抗病基因分析奠定物质基础。 相似文献
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Rad R Rad L Wang W Cadinanos J Vassiliou G Rice S Campos LS Yusa K Banerjee R Li MA de la Rosa J Strong A Lu D Ellis P Conte N Yang FT Liu P Bradley A 《Science (New York, N.Y.)》2010,330(6007):1104-1107
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Region-specific expression of two mouse homeo box genes 总被引：15，自引：0，他引：15
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中国小麦抗纹枯病育种研究进展 总被引：3，自引：0，他引：3
由禾谷丝核菌(Rhizoctonia cerealis vander hoeven)和立枯丝核菌(Rhizoctonia solani Kuha)引起的小麦纹枯病是中国长江流域和黄淮平原麦区的严重病害之一.该文系统综述了中国在小麦抗纹枯病种质资源筛选、抗性遗传、抗性基因定位和分子标记以及抗病种质创新和抗病育种等方面的最新进展.尽管在小麦改良品种中尚未发现对纹枯病高抗的类型,但在地方品种、国外引进品种和小麦近缘种属中则有高抗甚至免疫的种质.小麦抗纹枯病性表现为数量性状的遗传特征,抗性可能受2对主效基因和一些微效基因共同控制.通过品种间杂交,累加和聚合抗病基因可以创制抗病丰产的新种质.文中就如何加快国内小麦抗纹枯病育种步伐,提出了几点建议. 相似文献