Transgene Coplacement and high efficiency site-specific recombination with the Cre/loxP system in Drosophila.
Transgene Coplacement and high efficiency site-specific recombination with the Cre/loxP system in Drosophila.
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作者：
M. Siegal;D. Hartl
转基因果蝇中基因功能和调控的研究经常受到基因组位置对基因表达影响的可能性的影响。我们已经开发了一种称为转基因共定位的方法，其中任何两个序列可以定位在基因组中完全相同的位点和方向。转基因共定位利用噬菌体P1系统的Cre/loxP位点特异性重组，我们已经引入果蝇。在由双hsp 70-Mos 1启动子驱动的cre转基因的存在下，在体细胞和生殖细胞中几乎100%效率地切除侧接loxP位点的白色报告基因。由卵母细胞中存在的Cre重组酶引起的强烈的母体效应在F1子代中观察到为白色或马赛克眼睛颜色。切除生殖细胞的F1产生了强烈的祖母效应，观察到的F2代的眼睛颜色表型的高度倾斜的比例。Cre/loxP的切除反应和相关的FLP/FRT系统用于创建转基因位于同源染色体中的精确等位位点的果蝇品系。
Studies of gene function and regulation in transgenic Drosophila are often compromised by the possibility of genomic position effects on gene expression. We have developed a method called transgene coplacement, in which any two sequences can be positioned at exactly the same site and orientation in the genome. Transgene coplacement makes use of the bacteriophage P1 system of Cre/loxP site-specific recombination, which we have introduced into Drosophila. In the presence of a cre transgene driven by a dual hsp70-Mos1 promoter, a white reporter gene flanked by loxP sites is excised with virtually 100% efficiency both in somatic cells and in germ cells. A strong maternal effect, resulting from Cre recombinase present in the oocyte, is observed as white or mosaic eye color in F1 progeny. Excision in germ cells of the F1 yields a strong grand-maternal effect, observed as a highly skewed ratio of eye-color phenotypes in the F2 generation. The excision reactions of Cre/loxP and the related FLP/FRT system are used to create Drosophila lines in which transgenes are at exactly allelic sites in homologous chromosomes.