Chase B A, Baker B S
Department of Biological Sciences, Stanford University, California 94305, USA.
Genetics. 1995 Apr;139(4):1649-61. doi: 10.1093/genetics/139.4.1649.
Sex-type in Drosophila melanogaster is controlled by a hierarchically acting set of regulatory genes. At the terminus of this hierarchy lie those regulatory genes responsible for implementing sexual differentiation: genes that control the activity of target loci whose products give rise to sexually dimorphic phenotypes. The genetic analysis of the intersex (ix) gene presented here demonstrates that ix is such a terminally positioned regulatory locus. The ix locus has been localized to the cytogenetic interval between 47E3-6 and 47F11-18. A comparison of the morphological and behavioral phenotypes of homozygotes and hemizygotes for three point mutations at ix indicates that the null phenotype of ix is to transform diplo-X animals into intersexes while leaving haplo-X animals unaffected. Analysis of X-ray induced, mitotic recombination clones lacking ix+ function in the abdomen of diplo-X individuals indicates that the ix+ product functions in a cell-autonomous manner and that it is required at least until the termination of cell division in this tissue. Taken together with previous analyses, our results indicate that the ix+ product is required to function with the female-specific product of doublesex to implement appropriate female sexual differentiation in diplo-X animals.
黑腹果蝇的性别类型由一组层级作用的调控基因控制。在这个层级结构的末端是那些负责实现性别分化的调控基因：这些基因控制着靶位点的活性，其产物会产生两性异形的表型。本文对双性（ix）基因的遗传分析表明，ix就是这样一个处于末端位置的调控位点。ix位点已定位到细胞遗传学区间47E3 - 6和47F11 - 18之间。对ix位点上三个点突变的纯合子和半合子的形态和行为表型进行比较表明，ix的无效表型是将双倍体X动物转变为雌雄间体，而单倍体X动物不受影响。对双倍体X个体腹部缺乏ix +功能的X射线诱导的有丝分裂重组克隆进行分析表明，ix +产物以细胞自主的方式发挥作用，并且至少在该组织的细胞分裂终止之前是必需的。结合先前的分析，我们的结果表明，在双倍体X动物中，ix +产物需要与双性的雌性特异性产物共同作用，以实现适当的雌性性别分化。
