RESUMO
To investigate the role of juvenile hormone (JH) in the control of Drosophila reproduction under stress, JH degradation and reproduction were studied under nutritional stress and JH treatment in Drosophila virilis females of wild type (wt) and a heat stress (hs) mutant: this mutant does not respond to heat stress by alterations in JH metabolism and has decreased JH level and fertility under normal conditions. One day of starvation results in a decrease of JH degradation, a delay in oocyte maturation, degradation of early vitellogenic egg chambers, accumulation of mature oocytes and a 24 h oviposition arrest in both wt and hs females. A fertility decrease was observed in both wt and hs females 24 h following the end of starvation. JH treatment leads to a decrease of JH degradation and an arrest of oviposition for 24 h in fed females. JH treatment prior to starvation seems to protect some oocytes from resorption: in JH-treated wt females, fertility increases rapidly following the end of starvation. The dynamics of JH degradation and fertility are similar following starvation and JH treatment. The role of JH in the accumulation of mature oocytes and the delay of oviposition under stress are discussed.
Assuntos
Drosophila/fisiologia , Privação de Alimentos/fisiologia , Hormônios Juvenis/fisiologia , Estresse Fisiológico/metabolismo , Animais , Drosophila/efeitos dos fármacos , Drosophila/genética , Feminino , Fertilidade/efeitos dos fármacos , Temperatura Alta/efeitos adversos , Hormônios Juvenis/metabolismo , Hormônios Juvenis/farmacologia , Mutação , Oócitos/efeitos dos fármacos , Oócitos/fisiologia , Oogênese/efeitos dos fármacos , Oogênese/fisiologia , Oviposição/efeitos dos fármacos , Oviposição/fisiologia , Reprodução/efeitos dos fármacos , Reprodução/fisiologia , Fatores de TempoRESUMO
The link between reproduction and environmental signals is poorly understood at the physiological, genetic and molecular levels. We describe a mutant strain of Drosophila virilis that has altered responses to heat stress. Heat stress in wild-type females results in oocyte maturation delays, degradation of early vitellogenic egg chambers, inhibition of yolk protein gene expression in follicle cells and accumulation of mature oocytes. The mutant females have increased levels of ecdysteroids and decreased juvenile hormone degradation, and show all of the heat-stress-induced reproductive effects observed in wild-type flies, without exposure to heat stress. During oogenesis in mutant females following heat stress there is an increase in early vitellogenic oocyte degradation and some degradation of late egg chambers. 20-Hydroxyecdysone levels, but not juvenile hormone degradation, change following heat stress in mutant females.
