Control of the mid-blastula transition in Drosophila

描述(申请人提供)：在果蝇胚胎的第14次分裂中，快速的母性驱动周期结束，合子调节开始。这一转变被称为胚泡中期转变(MBT)，它协调多种细胞事件，以确保发育的保真度。这项建议试图描述细胞周期蛋白：CDK活性的滴定和染色质修饰的变化如何影响MBT。通过改变Cyclin：CDK的活性，我们将通过实时荧光显微镜监测细胞周期计时，通过注射标记核苷酸监测复制动态，通过原位杂交监测关键基因的转录。“组蛋白密码”的持续特征将定义MBT染色质修饰的变化，向分期胚胎中注入去乙酰酶抑制剂将直接测试染色质状态如何影响MBT和复制。最后，将使用Cyclin：CDK调节、不可降解的Cyclins和CDK抑制剂的突变体来研究Cyclin：CDK活性和组蛋白修饰之间的关系。了解MBT和细胞周期转变不仅对于识别基本发育很重要，而且对于阐明这一过程中的缺陷如何导致包括癌症和出生缺陷在内的异常也很重要。

DESCRIPTION (provided by applicant): In the 14th division of the Drosophila embryo, the rapid maternally driven cycles end and zygotic regulation begins. This transition, referred to as the mid-blastula transition (MBT), coordinates a multitude of cellular events to ensure developmental fidelity. This proposal seeks to characterize how titration of cyclin:Cdk activity and changes in chromatin modifications influence the MBT. By genetically altering cyclin:cdk activity, we will monitor: cell cycle timing by real time flourescence microscopy, replication dynamics by injecting labeled nucleotides, and the transcription of key genes by in situ hybridization. Continued characterization of the "histone code" will define changes in chromatin modifications at the MBT and injecting deacetlyase inhibitors into staged embryos will directly test how chromatin state influences the MBT and replication. Finally, the relationship between cyclin:Cdk activity and histone modifications will be examined using mutants of cyclin:Cdk regulation, non-degradable cyclins, and Cdk inhibitors. Understanding the MBT and cell cycle transitions is important not only in discerning basic development, but in elucidating how defects in this process lead to abnormalities, including cancer and birth defects.