A maleness gene in the malaria mosquito Anopheles gambiae

Female-fatal product of the Yob gene Mechanisms of sex determination are highly variable and complex in invertebrates. For vector-borne disease control strategies, it is important to understand the reproductive biology of the organisms involved. Krzywinska et al. have studied sex determination in species of Anopheles mosquitoes, whose females suck blood and can transmit malaria parasites (see the Perspective by Sinkins). One gene called Yob is found only on the Y chromosome of males. Yob is expressed in male embryos within 2 hours of eggs being laid, and transcription continues lifelong. If Yob is injected into embryos younger than 2 hours, only male mosquitoes emerge, because Yob 's presence is lethal to female embryos. Science , this issue p. 67 ; see also p. 33