首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   22篇
  免费   0篇
现状及发展   8篇
研究方法   4篇
综合类   10篇
  2015年   1篇
  2012年   1篇
  2008年   2篇
  2007年   2篇
  2006年   2篇
  2004年   1篇
  2002年   2篇
  2001年   1篇
  1990年   2篇
  1986年   1篇
  1985年   1篇
  1983年   1篇
  1982年   1篇
  1978年   1篇
  1976年   2篇
  1955年   1篇
排序方式: 共有22条查询结果,搜索用时 15 毫秒
1.
2.
Tanaka S  Umemori T  Hirai K  Muramatsu S  Kamimura Y  Araki H 《Nature》2007,445(7125):328-332
In eukaryotic cells, cyclin-dependent kinases (CDKs) have an important involvement at various points in the cell cycle. At the onset of S phase, active CDK is essential for chromosomal DNA replication, although its precise role is unknown. In budding yeast (Saccharomyces cerevisiae), the replication protein Sld2 (ref. 2) is an essential CDK substrate, but its phospho-mimetic form (Sld2-11D) alone neither affects cell growth nor promotes DNA replication in the absence of CDK activity, suggesting that other essential CDK substrates promote DNA replication. Here we show that both an allele of CDC45 (JET1) and high-copy DPB11, in combination with Sld2-11D, separately confer CDK-independent DNA replication. Although Cdc45 is not an essential CDK substrate, CDK-dependent phosphorylation of Sld3, which associates with Cdc45 (ref. 5), is essential and generates a binding site for Dpb11. Both the JET1 mutation and high-copy DPB11 by-pass the requirement for Sld3 phosphorylation in DNA replication. Because phosphorylated Sld2 binds to the carboxy-terminal pair of BRCT domains in Dpb11 (ref. 4), we propose that Dpb11 connects phosphorylated Sld2 and Sld3 to facilitate interactions between replication proteins, such as Cdc45 and GINS. Our results demonstrate that CDKs regulate interactions between BRCT-domain-containing replication proteins and other phosphorylated proteins for the initiation of chromosomal DNA replication; similar regulation may take place in higher eukaryotes.  相似文献   
3.
The medaka draft genome and insights into vertebrate genome evolution   总被引:3,自引:0,他引:3  
Teleosts comprise more than half of all vertebrate species and have adapted to a variety of marine and freshwater habitats. Their genome evolution and diversification are important subjects for the understanding of vertebrate evolution. Although draft genome sequences of two pufferfishes have been published, analysis of more fish genomes is desirable. Here we report a high-quality draft genome sequence of a small egg-laying freshwater teleost, medaka (Oryzias latipes). Medaka is native to East Asia and an excellent model system for a wide range of biology, including ecotoxicology, carcinogenesis, sex determination and developmental genetics. In the assembled medaka genome (700 megabases), which is less than half of the zebrafish genome, we predicted 20,141 genes, including approximately 2,900 new genes, using 5'-end serial analysis of gene expression tag information. We found single nucleotide polymorphisms (SNPs) at an average rate of 3.42% between the two inbred strains derived from two regional populations; this is the highest SNP rate seen in any vertebrate species. Analyses based on the dense SNP information show a strict genetic separation of 4 million years (Myr) between the two populations, and suggest that differential selective pressures acted on specific gene categories. Four-way comparisons with the human, pufferfish (Tetraodon), zebrafish and medaka genomes revealed that eight major interchromosomal rearrangements took place in a remarkably short period of approximately 50 Myr after the whole-genome duplication event in the teleost ancestor and afterwards, intriguingly, the medaka genome preserved its ancestral karyotype for more than 300 Myr.  相似文献   
4.
5.
Many insects that rely on a single food source throughout their developmental cycle harbor beneficial microbes that provide nutrients absent from their restricted diet. Tsetse flies, the vectors of African trypanosomes, feed exclusively on blood and rely on one such intracellular microbe for nutritional provisioning and fecundity. As a result of co-evolution with hosts over millions of years, these mutualists have lost the ability to survive outside the sheltered environment of their host insect cells. We present the complete annotated genome of Wigglesworthia glossinidia brevipalpis, which is composed of one chromosome of 697,724 base pairs (bp) and one small plasmid, called pWig1, of 5,200 bp. Genes involved in the biosynthesis of vitamin metabolites, apparently essential for host nutrition and fecundity, have been retained. Unexpectedly, this obligate's genome bears hallmarks of both parasitic and free-living microbes, and the gene encoding the important regulatory protein DnaA is absent.  相似文献   
6.
Summary Both ischemia and ethionine decreased the membrane potential and ATP content in rat liver. In ethioninetreated rat liver, ischemia brought about a further decrease in membrane potential without significant decrease in ATP content.  相似文献   
7.
8.
Y Shiba  Y Kanno 《Experientia》1990,46(5):492-495
Addition of epidermal growth factor to culture medium without calf serum suppressed the increase in cell volume and then enhanced the survival of BSC-1 cells attached to culture dishes. However, these effects of epidermal growth factor were not observed in the case of cells on dishes coated with heat-denatured bovine serum albumin.  相似文献   
9.
T Shiba  S Nomoto  T Wakamiya 《Experientia》1976,32(9):1109-1111
The chemical structure of capreomycin, antituberculous peptide antibiotic, was revised from the results of NMR-analysis in comparison with tuberactinomycins. Capreomycin IA and IB were concluded to possess the similar amino acid sequences in their cyclic peptide moieties to those of tuberactinomycins.  相似文献   
10.
Transplantation studies in mice and rats have shown that human embryonic-stem-cell-derived cardiomyocytes (hESC-CMs) can improve the function of infarcted hearts, but two critical issues related to their electrophysiological behaviour in vivo remain unresolved. First, the risk of arrhythmias following hESC-CM transplantation in injured hearts has not been determined. Second, the electromechanical integration of hESC-CMs in injured hearts has not been demonstrated, so it is unclear whether these cells improve contractile function directly through addition of new force-generating units. Here we use a guinea-pig model to show that hESC-CM grafts in injured hearts protect against arrhythmias and can contract synchronously with host muscle. Injured hearts with hESC-CM grafts show improved mechanical function and a significantly reduced incidence of both spontaneous and induced ventricular tachycardia. To assess the activity of hESC-CM grafts in vivo, we transplanted hESC-CMs expressing the genetically encoded calcium sensor, GCaMP3 (refs 4, 5). By correlating the GCaMP3 fluorescent signal with the host ECG, we found that grafts in uninjured hearts have consistent 1:1 host–graft coupling. Grafts in injured hearts are more heterogeneous and typically include both coupled and uncoupled regions. Thus, human myocardial grafts meet physiological criteria for true heart regeneration, providing support for the continued development of hESC-based cardiac therapies for both mechanical and electrical repair.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号