Arthur B I, Jallon J M, Caflisch B, Choffat Y, Nöthiger R
Zoological Institute University of Zurich Winterthurerstrasse. 190, CH-8057, Zurich, Switzerland.
Curr Biol. 1998 Oct 22;8(21):1187-90. doi: 10.1016/s0960-9822(07)00491-5.
Sexual differentiation in Drosophila is controlled by a short cascade of regulatory genes, the expression pattern of which determines all aspects of maleness and femaleness, including complex behaviours displayed by males and females [1-3]. One sex-determining gene is transformer (tra), the activity of which is needed for female development. Flies with a female karyotype (XX) but which are mutant for tra develop and behave as males. In such flies, a female phenotype can be restored by a transgene that carries the female-specific cDNA of tra under the control of a heat-shock promoter. This transgene, called hs[trafem], also transforms XY animals into sterile females [4]. When we raised these XX and XY 'females' at 25 degreesC, however, they displayed vigorous male courtship while at the same time, as a result of their female pheromone pattern, they were attractive to males. Intriguingly, their male courtship behaviour was indiscriminately directed towards both females and males. When we forced expression of tra by heat shock, applied during a limited period around puparium formation, male behaviour was abolished and replaced by female behaviour. We conclude that sexual behaviour is irreversibly programmed during a critical period as a result of the activity or inactivity of a single control gene.
果蝇的性别分化由一小串调控基因控制，这些基因的表达模式决定了雄性和雌性的所有方面，包括雄性和雌性表现出的复杂行为[1-3]。一个性别决定基因是transformer（tra），其活性是雌性发育所必需的。具有雌性核型（XX）但tra基因发生突变的果蝇发育并表现为雄性。在这种果蝇中，携带在热休克启动子控制下的tra雌性特异性cDNA的转基因可以恢复雌性表型。这个名为hs[trafem]的转基因也能将XY动物转化为不育雌性[4]。然而，当我们在25摄氏度饲养这些XX和XY“雌性”时，它们表现出强烈的雄性求偶行为，同时，由于它们的雌性信息素模式，它们对雄性有吸引力。有趣的是，它们的雄性求偶行为不加区分地指向雌性和雄性。当我们在蛹形成前后的有限时间内通过热休克强制tra表达时，雄性行为被消除并被雌性行为取代。我们得出结论，由于单个控制基因的活性或无活性，性行为在关键时期被不可逆地编程。
