Control of the mid-blastula transition in Drosophila

描述（由申请人提供）：在果蝇胚胎的第14次分裂中，母体驱动的快速周期结束，合子调控开始。这种转变，被称为中囊胚转变（MBT），协调多种细胞事件以确保发育的保真度。本提案旨在描述细胞周期蛋白Cdk活性的滴定和染色质修饰的变化如何影响MBT。通过基因改变细胞周期蛋白cdk活性，我们将通过实时荧光显微镜监测细胞周期计时，通过注射标记的核苷酸监测复制动力学，通过原位杂交监测关键基因的转录。对“组蛋白代码”的持续表征将定义MBT中染色质修饰的变化，将脱乙酰酶抑制剂注射到分期胚胎中将直接测试染色质状态如何影响MBT和复制。最后，cyclin:Cdk活性和组蛋白修饰之间的关系将通过cyclin:Cdk调控突变体、不可降解的细胞周期蛋白和Cdk抑制剂来检验。了解MBT和细胞周期转变不仅对辨别基本发育很重要，而且对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.