Fortier E, Belote J M
Department of Biology, Syracuse University, Syracuse, New York, USA.
Genesis. 2000 Apr;26(4):240-4. doi: 10.1002/(sici)1526-968x(200004)26:4<240::aid-gene40>3.0.co;2-p.
Posttranscriptional gene silencing (PTGS) induced by double-stranded RNA (dsRNA) is an intriguing phenomenon that has been observed in a variety of organisms, including Drosophila melanogaster. Although PTGS in Drosophila is typically observed following direct injection of the dsRNA into embryos, it is theoretically possible that the in vivo transcription of an inverted repeat transgene might also produce a dsRNA "hairpin" that is capable of triggering PTGS. Here we test this idea, and show that an expressed inverted repeat of a portion of the sex differentiation gene, transformer-2, (tra-2), driven by a GAL4-dependent promoter, does genetically repress the endogenous wild-type tra-2 function, producing a dominant loss-of-function mutant phenotype. Remarkably, this effect is temperature-sensitive, with phenotypic consequences seen at 29 degrees, but not at 22 degrees. Moreover, by altering the dosage of either the transgenes or the endogenous tra2(+) loci, one can vary the effect over a wide range of mutant phenotypes.
双链RNA（dsRNA）诱导的转录后基因沉默（PTGS）是一种在包括黑腹果蝇在内的多种生物体中都观察到的有趣现象。虽然果蝇中的PTGS通常是在将dsRNA直接注射到胚胎后观察到的，但理论上，反向重复转基因的体内转录也可能产生能够触发PTGS的dsRNA“发夹”。在这里，我们测试了这个想法，并表明由GAL4依赖性启动子驱动的性别分化基因transformer-2（tra-2）一部分的表达反向重复序列在遗传上抑制了内源性野生型tra-2的功能，产生了显性功能丧失突变表型。值得注意的是，这种效应是温度敏感的，在29摄氏度时出现表型后果，而在22摄氏度时则没有。此外，通过改变转基因或内源性tra2(+)位点的剂量，可以在广泛的突变表型范围内改变这种效应。
