为了深入研究温度和光照等昼夜节律授时因子对家蚕滞育的调控机制,以常规诱导滞育发生的温度与光照条件处理胚胎发育后期蚕卵,调查家蚕胚胎生物钟信号环路主要基因Cry1、Cry2、Per和Tim的表达对授时因子振荡变化的响应。结果显示:光照能够上调Cry1基因在家蚕胚胎发育后期的表达,温度则可改变该基因表达的振荡周期相位;温度在改变Cry2基因振荡表达相位的同时,低温(15℃)还能上调该基因在家蚕胚胎发育后期的表达;温度升高可缩短Per基因表达的振荡周期;黑暗诱导Tim基因振荡表达,温度则能够改变Tim基因表达的振荡周期相位。结果提示:家蚕胚胎中可能存在与其他昆虫类似的以CRY1为光感受器因子的生物钟信号环路,Cry1、Cry2、Per和Tim是家蚕胚胎期能够响应昼夜节律授时因子光照和温度而诱导滞育发生的生物钟基因。
In order to elucidate the control mechanism of temperature,photoperiod and other circadian rhythm zeitgebers on diapause in the silkworm (Bombyx mori) ,silkworm eggs at late embryonic development stage were treated with normal diapause-inducing incubation temperature and photoperiod to investigate the response of expression of major circadian rhythm loop genes (Cry1,Cry2,Per and Tim) against zeitgebers oscillation.The results showed that light could upregulate the expression of Cry1 gene at late development stage of silkworm embryos,and temperature could change the oscillation cycle phase of Cry1 expression.While temperature was able to change the oscillation cycle phase of Cry2 gene expression,low temperature (15 ℃) could up-regulate the expression of Cry2 gene at late development stage of silkworm embryos.Elevated temperature could shorten the oscillation cycle of Per gene expression.Continuous darkness could induce oscillation of Tim gene expression and temperature could change the oscillation cycle phase of Tim gene expression.These results suggest that silkworm embryos have a circadian clock feedback loop with CRY1 as the photoreceptor which is similar to other insect species,and Cry1,Cry2,Per and Tim are circadian clock genes that respond to temperature and photoperiod circadian rhythm zeitgebers and induce diapause at silkworm embryonic development stage.