Goldberg M L, Colvin R A, Mellin A F
Section of Genetics and Development, Cornell University, Ithaca, New York 14853-2703.
Genetics. 1989 Sep;123(1):145-55. doi: 10.1093/genetics/123.1.145.
Diepoxybutane-induced mutations of the Drosophila zeste locus were generated in an effort to obtain a null allele. Of 33 mutations of this X-linked gene isolated, 16 were associated with multilocus deletions of zeste and adjacent complementation groups, while the remainder were defects restricted to zeste undetectable by Southern blot analysis. Two of these multilocus deletions (Df(1)zdeb3 and Df(1)zdeb92) were employed in the synthesis of females completely deleted for zeste. Such "zesteless" flies were produced, though at frequencies lower than Mendelian expectations. zeste-deleted females are fertile, and can give rise to zeste-deleted female progeny. These results demonstrate that the product of the zeste gene is not essential to viability or to female fertility, even if absent both as a maternal contribution and as a product of the zygotic genome. However, the possibility that zeste may influence relative viability cannot be excluded. In spite of previous in vitro indications that the zeste protein may activate transcription of the Ultrabithorax (Ubx) gene, zeste -deleted flies are Ubx+ in phenotype. This suggests that the zeste protein normally is either a very weak transcription factor, or that its function can be substituted by that of other regulatory proteins.
为了获得一个无效等位基因，产生了由二环氧丁烷诱导的果蝇小体基因座突变。在分离出的这个X连锁基因的33个突变中，16个与小体及相邻互补群的多位点缺失有关，而其余的是局限于小体的缺陷，通过Southern印迹分析无法检测到。其中两个多位点缺失（Df(1)zdeb3和Df(1)zdeb92）被用于合成完全缺失小体的雌性果蝇。这样的“无小体”果蝇产生了，尽管频率低于孟德尔预期。缺失小体的雌性果蝇是可育的，并且可以产生缺失小体的雌性后代。这些结果表明，即使小体基因的产物作为母体贡献和作为合子基因组的产物都不存在，它对生存能力或雌性生育能力也不是必需的。然而，不能排除小体可能影响相对生存能力的可能性。尽管先前的体外研究表明小体蛋白可能激活超双胸（Ubx）基因的转录，但缺失小体的果蝇在表型上是Ubx+。这表明小体蛋白通常要么是一种非常弱的转录因子，要么其功能可以被其他调节蛋白替代。
