排序方式: 共有40条查询结果,搜索用时 609 毫秒
1.
2.
3.
Thibault ST Singer MA Miyazaki WY Milash B Dompe NA Singh CM Buchholz R Demsky M Fawcett R Francis-Lang HL Ryner L Cheung LM Chong A Erickson C Fisher WW Greer K Hartouni SR Howie E Jakkula L Joo D Killpack K Laufer A Mazzotta J Smith RD Stevens LM Stuber C Tan LR Ventura R Woo A Zakrajsek I Zhao L Chen F Swimmer C Kopczynski C Duyk G Winberg ML Margolis J 《Nature genetics》2004,36(3):283-287
With the availability of complete genome sequence for Drosophila melanogaster, one of the next strategic goals for fly researchers is a complete gene knockout collection. The P-element transposon, the workhorse of D. melanogaster molecular genetics, has a pronounced nonrandom insertion spectrum. It has been estimated that 87% saturation of the approximately 13,500-gene complement of D. melanogaster might require generating and analyzing up to 150,000 insertions. We describe specific improvements to the lepidopteran transposon piggyBac and the P element that enabled us to tag and disrupt genes in D. melanogaster more efficiently. We generated over 29,000 inserts resulting in 53% gene saturation and a more diverse collection of phenotypically stronger insertional alleles. We found that piggyBac has distinct global and local gene-tagging behavior from that of P elements. Notably, piggyBac excisions from the germ line are nearly always precise, piggyBac does not share chromosomal hotspots associated with P and piggyBac is more effective at gene disruption because it lacks the P bias for insertion in 5' regulatory sequences. 相似文献
4.
Résumé L'effet d'un mélange des acidés aminés essentiels sur l'absorption de phénylalanine par l'intestin de rat a été étudié. On a trouvé que le mélange, s'il est en contact direct avec l'intestin, peut augmenter l'absorption de phénylalanine. Ces résultats sont interprétés et plusieurs hypothèses sont émises pour expliquer ce phénomène. 相似文献
5.
6.
The fluctuating characteristics (numbers, biomass, condition, and young-adult ratios) of the Lahontan (Humboldt) cutthroat trout population in Chimney Creek, Nevada, are discussed in relationship to the unpredictable and unstable habitat in which the population occurs. One possible means of adapting to environmental capriciousness, staggered spawning, occurred during 1982, and clues as to the cause of this unusual event are sought by examining the runoff hydrographs of a nearby watershed for 1981 through 1984. The management values of the environmental tolerance of these native trout with respect to restoring viable trout fisheries in degraded Great Basin streams are also considered. 相似文献
7.
Systematic generation of high-resolution deletion coverage of the Drosophila melanogaster genome 总被引:1,自引:0,他引:1
Parks AL Cook KR Belvin M Dompe NA Fawcett R Huppert K Tan LR Winter CG Bogart KP Deal JE Deal-Herr ME Grant D Marcinko M Miyazaki WY Robertson S Shaw KJ Tabios M Vysotskaia V Zhao L Andrade RS Edgar KA Howie E Killpack K Milash B Norton A Thao D Whittaker K Winner MA Friedman L Margolis J Singer MA Kopczynski C Curtis D Kaufman TC Plowman GD Duyk G Francis-Lang HL 《Nature genetics》2004,36(3):288-292
In fruit fly research, chromosomal deletions are indispensable tools for mapping mutations, characterizing alleles and identifying interacting loci. Most widely used deletions were generated by irradiation or chemical mutagenesis. These methods are labor-intensive, generate random breakpoints and result in unwanted secondary mutations that can confound phenotypic analyses. Most of the existing deletions are large, have molecularly undefined endpoints and are maintained in genetically complex stocks. Furthermore, the existence of haplolethal or haplosterile loci makes the recovery of deletions of certain regions exceedingly difficult by traditional methods, resulting in gaps in coverage. Here we describe two methods that address these problems by providing for the systematic isolation of targeted deletions in the D. melanogaster genome. The first strategy used a P element-based technique to generate deletions that closely flank haploinsufficient genes and minimize undeleted regions. This deletion set has increased overall genomic coverage by 5-7%. The second strategy used FLP recombinase and the large array of FRT-bearing insertions described in the accompanying paper to generate 519 isogenic deletions with molecularly defined endpoints. This second deletion collection provides 56% genome coverage so far. The latter methodology enables the generation of small custom deletions with predictable endpoints throughout the genome and should make their isolation a simple and routine task. 相似文献
8.
9.
10.
Protein farnesyltransferase (FTase) catalyses the attachment of a farnesyl lipid group to numerous essential signal transduction proteins, including members of the Ras superfamily. The farnesylation of Ras oncoproteins, which are associated with 30% of human cancers, is essential for their transforming activity. FTase inhibitors are currently in clinical trials for the treatment of cancer. Here we present a complete series of structures representing the major steps along the reaction coordinate of this enzyme. From these observations can be deduced the determinants of substrate specificity and an unusual mechanism in which product release requires binding of substrate, analogous to classically processive enzymes. A structural model for the transition state consistent with previous mechanistic studies was also constructed. The processive nature of the reaction suggests the structural basis for the successive addition of two prenyl groups to Rab proteins by the homologous enzyme geranylgeranyltransferase type-II. Finally, known FTase inhibitors seem to differ in their mechanism of inhibiting the enzyme. 相似文献