排序方式: 共有25条查询结果,搜索用时 15 毫秒
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Kao WH Klag MJ Meoni LA Reich D Berthier-Schaad Y Li M Coresh J Patterson N Tandon A Powe NR Fink NE Sadler JH Weir MR Abboud HE Adler SG Divers J Iyengar SK Freedman BI Kimmel PL Knowler WC Kohn OF Kramp K Leehey DJ Nicholas SB Pahl MV Schelling JR Sedor JR Thornley-Brown D Winkler CA Smith MW Parekh RS;Family Investigation of Nephropathy Diabetes Research Group 《Nature genetics》2008,40(10):1185-1192
As end-stage renal disease (ESRD) has a four times higher incidence in African Americans compared to European Americans, we hypothesized that susceptibility alleles for ESRD have a higher frequency in the West African than the European gene pool. We carried out a genome-wide admixture scan in 1,372 ESRD cases and 806 controls and found a highly significant association between excess African ancestry and nondiabetic ESRD (lod score = 5.70) but not diabetic ESRD (lod = 0.47) on chromosome 22q12. Each copy of the European ancestral allele conferred a relative risk of 0.50 (95% CI = 0.39-0.63) compared to African ancestry. Multiple common SNPs (allele frequencies ranging from 0.2 to 0.6) in the gene encoding nonmuscle myosin heavy chain type II isoform A (MYH9) were associated with two to four times greater risk of nondiabetic ESRD and accounted for a large proportion of the excess risk of ESRD observed in African compared to European Americans. 相似文献
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W. C. Dale E. Baer A. Keller R. R. Kohn 《Cellular and molecular life sciences : CMLS》1972,28(11):1293-1295
Zusammenfassung Es wird gezeigt, dass die zwischen gekreuzten Nicols für die Rattenschwanzsehne nachgewiesenen periodischen Bänder von fibrillären Strukturelementen ebener Wellenform abstammen und deren Ausstreckung das beobachtete Dehnungsverhalten erklärt2, das auch für andere Säugetiere zutrifft. 相似文献
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Establishing the conditions that promote the evolution of reproductive isolation and speciation has long been a goal in evolutionary biology. In ecological speciation, reproductive isolation between populations evolves as a by-product of divergent selection and the resulting environment-specific adaptations. The leading genetic model of reproductive isolation predicts that hybrid inferiority is caused by antagonistic epistasis between incompatible alleles at interacting loci. The fundamental link between divergent adaptation and reproductive isolation through genetic incompatibilities has been predicted, but has not been directly demonstrated experimentally. Here we empirically tested key predictions of speciation theory by evolving the initial stages of speciation in experimental populations of the yeast Saccharomyces cerevisiae. After replicate populations adapted to two divergent environments, we consistently observed the evolution of two forms of postzygotic isolation in hybrids: reduced rate of mitotic reproduction and reduced efficiency of meiotic reproduction. This divergent selection resulted in greater reproductive isolation than parallel selection, as predicted by the ecological speciation theory. Our experimental system allowed controlled comparison of the relative importance of ecological and genetic isolation, and we demonstrated that hybrid inferiority can be ecological and/or genetic in basis. Overall, our results show that adaptation to divergent environments promotes the evolution of reproductive isolation through antagonistic epistasis, providing evidence of a plausible common avenue to speciation and adaptive radiation in nature. 相似文献
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Bourlat SJ Juliusdottir T Lowe CJ Freeman R Aronowicz J Kirschner M Lander ES Thorndyke M Nakano H Kohn AB Heyland A Moroz LL Copley RR Telford MJ 《Nature》2006,444(7115):85-88
Deuterostomes comprise vertebrates, the related invertebrate chordates (tunicates and cephalochordates) and three other invertebrate taxa: hemichordates, echinoderms and Xenoturbella. The relationships between invertebrate and vertebrate deuterostomes are clearly important for understanding our own distant origins. Recent phylogenetic studies of chordate classes and a sea urchin have indicated that urochordates might be the closest invertebrate sister group of vertebrates, rather than cephalochordates, as traditionally believed. More remarkable is the suggestion that cephalochordates are closer to echinoderms than to vertebrates and urochordates, meaning that chordates are paraphyletic. To study the relationships among all deuterostome groups, we have assembled an alignment of more than 35,000 homologous amino acids, including new data from a hemichordate, starfish and Xenoturbella. We have also sequenced the mitochondrial genome of Xenoturbella. We support the clades Olfactores (urochordates and vertebrates) and Ambulacraria (hemichordates and echinoderms). Analyses using our new data, however, do not support a cephalochordate and echinoderm grouping and we conclude that chordates are monophyletic. Finally, nuclear and mitochondrial data place Xenoturbella as the sister group of the two ambulacrarian phyla. As such, Xenoturbella is shown to be an independent phylum, Xenoturbellida, bringing the number of living deuterostome phyla to four. 相似文献
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The 1-(2-chloroethyl)-1-nitrosoureas are potent anti-cancer drugs which produce DNA inter-strand cross-links in a two-step reaction sequence. The first step was proposed to be an addition of a chloroethyl group to a guanine-O6 position of DNA; the second step, which occurs over a period of several hours in the absence of free drug, could then form an interstrand cross-link by the slow reaction of the bound chloroethyl group with a nucleophilic site on the opposite DNA strand. The delay between the formation of chloroethyl monoadducts and the formation of inter-strand cross-links allows time for a DNA repair mechanism, capable of removing the monoadducts, to prevent the cross-linking. We recently proposed this mechanism to account for a difference in inter-strand cross-linking between a normal and a transformed human cell strain. Day and his coworkers (see refs 7, 8 and previous paper) found that some human tumour cell strains (designated Mer- phenotype) are deficient in the ability to repair O6-methylguanine lesions in DNA. We therefore hypothesized that the repair function that removes O6-methylguanine residues from DNA would also remove chloroethyl monoadducts and hence prevent chloroethylnitrosourea-induced inter-strand cross-linking. We now present evidence that supports this hypothesis and indicates also that the O6-methylguanine repair confers resistance to cell killing by chloroethylnitrosourea. 相似文献
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The microenvironment of the tumour-host interface 总被引:86,自引:0,他引:86
Throughout the entire process of cancer aetiology, progression and metastasis, the microenvironment of the local host tissue can be an active participant. Invasion occurs within a tumour-host microecology, where stroma and tumour cells exchange enzymes and cytokines that modify the local extracellular matrix, stimulate migration, and promote proliferation and survival. A new class of cancer therapies that targets this pathological communication interface between tumour cells and host cells is currently under development. 相似文献
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