Hilfiker-Kleiner D, Dübendorfer A, Hilfiker A, Nöthiger R
Institute of Zoology, University of Zürich, Switzerland.
Genetics. 1993 Aug;134(4):1187-94. doi: 10.1093/genetics/134.4.1187.
In the housefly, Musca domestica, a single dominant factor, M, determines maleness. Animals hemi-or heterozygous for M are males, whereas those without M develop as females. In certain strains, however, both sexes are homozygous for M, and an epistatic dominant factor, FD, dictates female development. The requirement for these factors was analyzed by producing, with mitotic recombination, mosaic animals consisting of genetically male and female cells. Removal of FD from an M/M;FD/+ cell at any time of larval development, even in the last larval instar, resulted in sex-reversal, i.e., in the development of a male clone in an otherwise female fly. In contrast, when M was removed from M/+ cells, the resulting clones remained male despite their female genotype, even when the removal of M happened at embryonic stages. The occurrence of spontaneous gynandromorphs, however, shows that the loss of M in individual nuclei prior to blastoderm formation causes the affected cells to adopt the female pathway. These results are consistent with the hypothesis that M is the primary sex-determining signal which sets the state of activity of the key gene F at around the blastoderm stage. Parallels and differences to the sex-determining system of Drosophila are discussed.
在家蝇（Musca domestica）中，一个单一的显性因子M决定雄性。M基因半合子或杂合子的动物为雄性，而没有M基因的则发育为雌性。然而，在某些品系中，两性均为M基因的纯合子，一个上位显性因子FD决定雌性发育。通过有丝分裂重组产生由遗传上的雄性和雌性细胞组成的嵌合体动物，分析了这些因子的需求情况。在幼虫发育的任何阶段，即使是在最后一龄幼虫期，从M/M;FD/+细胞中去除FD，都会导致性反转，即在原本为雌性的果蝇中发育出雄性克隆。相反，当从M/+细胞中去除M时，即使在胚胎阶段去除M，产生的克隆尽管具有雌性基因型，但仍保持雄性。然而，自发雌雄嵌合体的出现表明，在胚盘形成之前，单个细胞核中M的缺失会使受影响的细胞采用雌性发育途径。这些结果与以下假设一致，即M是主要的性别决定信号，它在胚盘阶段左右设定关键基因F的活性状态。文中还讨论了与果蝇性别决定系统的异同。
