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In order to establish a genetic model of the resistance to Phytophthora cupsici in Capsicum annuum genotype‘Line 29′, three experiments were conducted which included, as well as‘Line 29′, the susceptible genotype‘Morron INIA 224’and several of its F1, F2, F3 and backcrosses. Plants with 4–6 leaves were inoculated by irrigating the culture substrate with a zoospore suspension of isolate B 1. The F2 test was applied to the segregating generations to test whether there were one, two, three or four genes involved in the resistance. Additivity and equal weight of all the genes in the final effect were assumed. The hypothesis that best explained the results obtained was the one that assumed three genes in‘Line 29′; at least four alleles had to be present in any genotype for it to behave as resistant. The possible influence of isolate aggressiveness and inoculation method on the results is discussed. 相似文献
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Sorek R Zhu Y Creevey CJ Francino MP Bork P Rubin EM 《Science (New York, N.Y.)》2007,318(5855):1449-1452
Horizontal gene transfer, in which genetic material is transferred from the genome of one organism to that of another, has been investigated in microbial species mainly through computational sequence analyses. To address the lack of experimental data, we studied the attempted movement of 246,045 genes from 79 prokaryotic genomes into Escherichia coli and identified genes that consistently fail to transfer. We studied the mechanisms underlying transfer inhibition by placing coding regions from different species under the control of inducible promoters. Our data suggest that toxicity to the host inhibited transfer regardless of the species of origin and that increased gene dosage and associated increased expression may be a predominant cause for transfer failure. Although these experimental studies examined transfer solely into E. coli, a computational analysis of gene-transfer rates across available bacterial and archaeal genomes supports that the barriers observed in our study are general across the tree of life. 相似文献
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Chaplin WJ Kjeldsen H Christensen-Dalsgaard J Basu S Miglio A Appourchaux T Bedding TR Elsworth Y García RA Gilliland RL Girardi L Houdek G Karoff C Kawaler SD Metcalfe TS Molenda-Żakowicz J Monteiro MJ Thompson MJ Verner GA Ballot J Bonanno A Brandão IM Broomhall AM Bruntt H Campante TL Corsaro E Creevey OL Doğan G Esch L Gai N Gaulme P Hale SJ Handberg R Hekker S Huber D Jiménez A Mathur S Mazumdar A Mosser B New R Pinsonneault MH Pricopi D Quirion PO Régulo C Salabert D Serenelli AM 《Science (New York, N.Y.)》2011,332(6026):213-216
In addition to its search for extrasolar planets, the NASA Kepler mission provides exquisite data on stellar oscillations. We report the detections of oscillations in 500 solar-type stars in the Kepler field of view, an ensemble that is large enough to allow statistical studies of intrinsic stellar properties (such as mass, radius, and age) and to test theories of stellar evolution. We find that the distribution of observed masses of these stars shows intriguing differences to predictions from models of synthetic stellar populations in the Galaxy. 相似文献
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Ciccarelli FD Doerks T von Mering C Creevey CJ Snel B Bork P 《Science (New York, N.Y.)》2006,311(5765):1283-1287
We have developed an automatable procedure for reconstructing the tree of life with branch lengths comparable across all three domains. The tree has its basis in a concatenation of 31 orthologs occurring in 191 species with sequenced genomes. It revealed interdomain discrepancies in taxonomic classification. Systematic detection and subsequent exclusion of products of horizontal gene transfer increased phylogenetic resolution, allowing us to confirm accepted relationships and resolve disputed and preliminary classifications. For example, we place the phylum Acidobacteria as a sister group of delta-Proteobacteria, support a Gram-positive origin of Bacteria, and suggest a thermophilic last universal common ancestor. 相似文献
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