Alvarez Mercedes, Ruiz María Fernanda, Sánchez Lucas
Centro de Investigaciones Biológicas (CSIC), Madrid, Spain.
PLoS One. 2009;4(4):e5141. doi: 10.1371/journal.pone.0005141. Epub 2009 Apr 2.
The gene doublesex (dsx) is at the bottom of the sex determination genetic cascade and is transcribed in both sexes, but gives rise to two different proteins, DsxF and DsxM, which impose female and male sexual development respectively via the sex-specific regulation of the so-called sexual cyto-differentiation genes. The present manuscript addressed the question about the functional conservation of the tephritid Anastrepha DsxF and DsxM proteins to direct the sexual development in Drosophila (Drosophilidae).
To express these proteins in Drosophila, the GAL4-UAS system was used. The effect of these proteins was monitored in the sexually dimorphic regions of the fly: the foreleg basitarsus, the 5th, 6th and 7th tergites, and the external terminalia. In addition, we analysed the effect of Anastrepha DsxF and DsxM proteins on the regulation of Drosophila yolk protein genes, which are expressed in the fat body of adult females under the control of dsx.
The Anastrepha DsxF and DsxM proteins transformed doublesex intersexual Drosophila flies into females and males respectively, though this transformation was incomplete and the extent of their influence varied in the different sexually dimorphic regions of the adult fly. The Anastrepha DsxF and DsxM proteins also behaved as activators and repressors, respectively, of the Drosophila yolk protein genes, as do the DsxF and DsxM proteins of Drosophila itself. Finally, the Anastrepha DsxF and DsxM proteins were found to counteract the functions of Drosophila DsxM and DsxF respectively, reflecting the normal behaviour of the latter proteins towards one another. Collectively, these results indicate that the Anastrepha DsxF and DsxM proteins show conserved female and male sex-determination function respectively in Drosophila, though it appears that they cannot fully substitute the latter's own Dsx proteins. This incomplete function might be partly due to a reduced capacity of the Anastrepha Dsx proteins to completely control the Drosophila sexual cyto-differentiation genes, a consequence of the accumulation of divergence between these species resulting in the formation of different co-adapted complexes between the Dsx proteins and their target genes.
双性基因（dsx）处于性别决定遗传级联的底部，在两性中均有转录，但会产生两种不同的蛋白质，即DsxF和DsxM，它们分别通过对所谓的性别细胞分化基因的性别特异性调控来决定雌性和雄性的性发育。本论文探讨了实蝇科果实蝇属的DsxF和DsxM蛋白在指导果蝇（果蝇科）性发育方面功能保守性的问题。
为了在果蝇中表达这些蛋白质，使用了GAL4-UAS系统。在果蝇的性别二态性区域监测这些蛋白质的作用：前足基跗节、第5、6和7腹节以及外部生殖器。此外，我们分析了果实蝇属的DsxF和DsxM蛋白对果蝇卵黄蛋白基因调控的影响，这些基因在成年雌性果蝇脂肪体中在dsx的控制下表达。
果实蝇属的DsxF和DsxM蛋白分别将双性间性果蝇转化为雌性和雄性，尽管这种转化并不完全，且它们在成年果蝇不同的性别二态性区域的影响程度有所不同。果实蝇属的DsxF和DsxM蛋白也分别表现为果蝇卵黄蛋白基因的激活剂和抑制剂，就像果蝇自身的DsxF和DsxM蛋白一样。最后，发现果实蝇属的DsxF和DsxM蛋白分别抵消了果蝇DsxM和DsxF的功能，反映了后两种蛋白彼此之间的正常行为。总体而言，这些结果表明，果实蝇属的DsxF和DsxM蛋白在果蝇中分别显示出保守的雌性和雄性性别决定功能，尽管它们似乎不能完全替代果蝇自身的Dsx蛋白。这种不完全的功能可能部分是由于果实蝇属的Dsx蛋白完全控制果蝇性别细胞分化基因的能力降低，这是这些物种之间差异积累的结果，导致Dsx蛋白与其靶基因之间形成了不同的共适应复合体。
