Steinmann-Zwicky M
Institute of Zoology, University Zurich-Irchel, Switzerland.
Development. 1993 Feb;117(2):763-7. doi: 10.1242/dev.117.2.763.
In soma and germ cells of Drosophila, the X:A ratio builds a primary signal for sex determination, and in both tissues Sex-lethal (Sxl) function is required for cells to enter the female pathway. In somatic cells of XX animals, the products of X-chromosomal elements of the X:A ratio activate Sxl. Here I show that sisterless-b (sis-b), which is the X-chromosomal element of the somatic X:A ratio that has best been analysed, is not required for oogenesis. I also present evidence that Sxl function might not be sufficient to direct germ cells into the female pathway. These results show that the elements forming the X:A ratio in the germ line are different from the elements forming the X:A ratio in the soma and they suggest that, in the germ line, Sxl might not be regulated by the X:A ratio.
在果蝇的体细胞和生殖细胞中，X:A 比值构建了性别决定的主要信号，并且在这两种组织中，细胞进入雌性发育途径都需要性致死基因（Sex-lethal，Sxl）发挥作用。在 XX 动物的体细胞中，X:A 比值中 X 染色体元件的产物激活 Sxl。在这里我表明，无姐妹基因 b（sisterless-b，sis-b），即体细胞 X:A 比值中研究得最为透彻的 X 染色体元件，对于卵子发生并非必需。我还提供了证据表明，Sxl 的功能可能不足以引导生殖细胞进入雌性发育途径。这些结果表明，在生殖系中形成 X:A 比值的元件与在体细胞中形成 X:A 比值的元件不同，并且它们表明，在生殖系中，Sxl 可能不受 X:A 比值的调控。
