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High-throughput sequencing provides insights into genome variation and evolution in Salmonella Typhi 总被引:1,自引:0,他引:1
Holt KE Parkhill J Mazzoni CJ Roumagnac P Weill FX Goodhead I Rance R Baker S Maskell DJ Wain J Dolecek C Achtman M Dougan G 《Nature genetics》2008,40(8):987-993
Isolates of Salmonella enterica serovar Typhi (Typhi), a human-restricted bacterial pathogen that causes typhoid, show limited genetic variation. We generated whole-genome sequences for 19 Typhi isolates using 454 (Roche) and Solexa (Illumina) technologies. Isolates, including the previously sequenced CT18 and Ty2 isolates, were selected to represent major nodes in the phylogenetic tree. Comparative analysis showed little evidence of purifying selection, antigenic variation or recombination between isolates. Rather, evolution in the Typhi population seems to be characterized by ongoing loss of gene function, consistent with a small effective population size. The lack of evidence for antigenic variation driven by immune selection is in contrast to strong adaptive selection for mutations conferring antibiotic resistance in Typhi. The observed patterns of genetic isolation and drift are consistent with the proposed key role of asymptomatic carriers of Typhi as the main reservoir of this pathogen, highlighting the need for identification and treatment of carriers. 相似文献
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Résumé Nous avons observé que l'inhibiteur d'enzymes protéolytiques (Zymofren-Specia) inhibe la transformation blastique des lymphocytes sensibilisés de cobaye évoquee par la phytohémagglutinine ou l'antigène. Nous n'avons pas observé d'influence ce de produit sur la consommation d'oxygène. 相似文献
4.
Melanoma mouse model implicates metabotropic glutamate signaling in melanocytic neoplasia 总被引:3,自引:0,他引:3
Pollock PM Cohen-Solal K Sood R Namkoong J Martino JJ Koganti A Zhu H Robbins C Makalowska I Shin SS Marin Y Roberts KG Yudt LM Chen A Cheng J Incao A Pinkett HW Graham CL Dunn K Crespo-Carbone SM Mackason KR Ryan KB Sinsimer D Goydos J Reuhl KR Eckhaus M Meltzer PS Pavan WJ Trent JM Chen S 《Nature genetics》2003,34(1):108-112
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Heike Betat Christiane Rammelt Mario Mörl 《Cellular and molecular life sciences : CMLS》2010,67(9):1447-1463
RNA polymerases are important enzymes involved in the realization of the genetic information encoded in the genome. Thereby,
DNA sequences are used as templates to synthesize all types of RNA. Besides these classical polymerases, there exists another
group of RNA polymerizing enzymes that do not depend on nucleic acid templates. Among those, tRNA nucleotidyltransferases
show remarkable and unique features. These enzymes add the nucleotide triplet C–C–A to the 3′-end of tRNAs at an astonishing
fidelity and are described as “CCA-adding enzymes”. During this incorporation of exactly three nucleotides, the enzymes have
to switch from CTP to ATP specificity. How these tasks are fulfilled by rather simple and small enzymes without the help of
a nucleic acid template is a fascinating research area. Surprising results of biochemical and structural studies allow scientists
to understand at least some of the mechanistic principles of the unique polymerization mode of these highly unusual enzymes. 相似文献
6.
Pauline Ferraris Elodie Beaumont Rustem Uzbekov Denys Brand Julien Gaillard Emmanuelle Blanchard Philippe Roingeard 《Cellular and molecular life sciences : CMLS》2013,70(7):1297-1306
Like most positive-strand RNA viruses, hepatitis C virus (HCV) forms a membrane-associated replication complex consisting of replicating RNA, viral and host proteins anchored to altered cell membranes. We used a combination of qualitative and quantitative electron microscopy (EM), immuno-EM, and the 3D reconstruction of serial EM sections to analyze the host cell membrane alterations induced by HCV. Three different types of membrane alteration were observed: vesicles in clusters (ViCs), contiguous vesicles (CVs), and double-membrane vesicles (DMVs). The main ultrastructural change observed early in infection was the formation of a network of CVs surrounding the lipid droplets. Later stages in the infectious cycle were characterized by a large increase in the number of DMVs, which may be derived from the CVs. These DMVs are thought to constitute the membranous structures harboring the viral replication complexes in which viral replication is firmly and permanently established and to protect the virus against double-stranded RNA-triggered host antiviral responses. 相似文献
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A zebrafish homologue of the chemokine receptor Cxcr4 is a germ-cell guidance receptor 总被引:18,自引:0,他引:18
Knaut H Werz C Geisler R Nüsslein-Volhard C;Tübingen Screen Consortium 《Nature》2003,421(6920):279-282
Germ cells preserve an individual's genetic information and transmit it to the next generation. Early in development germ cells are set aside and undergo a specialized developmental programme, a hallmark of which is the migration from their site of origin to the future gonad. In Drosophila, several factors have been identified that control germ-cell migration to their target tissues; however, the germ-cell chemoattractant or its receptor have remained unknown. Here we apply genetics and in vivo imaging to show that odysseus, a zebrafish homologue of the G-protein-coupled chemokine receptor Cxcr4, is required specifically in germ cells for their chemotaxis. odysseus mutant germ cells are able to activate the migratory programme, but fail to undergo directed migration towards their target tissue, resulting in randomly dispersed germ cells. SDF-1, the presumptive cognate ligand for Cxcr4, shows a similar loss-of-function phenotype and can recruit germ cells to ectopic sites in the embryo, thus identifying a vertebrate ligand-receptor pair guiding migratory germ cells at all stages of migration towards their target. 相似文献
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IntroductionSincethelate 1970salargenumberofstudieshaveconsideredirrigationschedulinginirrigationmanagement[1- 7] andithasbeenshownthatefficientand profitableirrigationschedulingstrategiesareneeded ,particularlywherewateravailableforirrigationislimited .Inno… 相似文献
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Mutations in the gene encoding the 3'-5' DNA exonuclease TREX1 are associated with systemic lupus erythematosus 总被引:1,自引:0,他引:1
Lee-Kirsch MA Gong M Chowdhury D Senenko L Engel K Lee YA de Silva U Bailey SL Witte T Vyse TJ Kere J Pfeiffer C Harvey S Wong A Koskenmies S Hummel O Rohde K Schmidt RE Dominiczak AF Gahr M Hollis T Perrino FW Lieberman J Hübner N 《Nature genetics》2007,39(9):1065-1067
TREX1 acts in concert with the SET complex in granzyme A-mediated apoptosis, and mutations in TREX1 cause Aicardi-Goutières syndrome and familial chilblain lupus. Here, we report monoallelic frameshift or missense mutations and one 3' UTR variant of TREX1 present in 9/417 individuals with systemic lupus erythematosus but absent in 1,712 controls (P = 4.1 x 10(-7)). We demonstrate that two mutant TREX1 alleles alter subcellular targeting. Our findings implicate TREX1 in the pathogenesis of SLE. 相似文献
10.
Anttonen AK Mahjneh I Hämäläinen RH Lagier-Tourenne C Kopra O Waris L Anttonen M Joensuu T Kalimo H Paetau A Tranebjaerg L Chaigne D Koenig M Eeg-Olofsson O Udd B Somer M Somer H Lehesjoki AE 《Nature genetics》2005,37(12):1309-1311
We identified the gene underlying Marinesco-Sj?gren syndrome, which is characterized by cerebellar ataxia, progressive myopathy and cataracts. We identified four disease-associated, predicted loss-of-function mutations in SIL1, which encodes a nucleotide exchange factor for the heat-shock protein 70 (HSP70) chaperone HSPA5. These data, together with the similar spatial and temporal patterns of tissue expression of Sil1 and Hspa5, suggest that disturbed SIL1-HSPA5 interaction and protein folding is the primary pathology in Marinesco-Sj?gren syndrome. 相似文献