Regulating the mid-blastula transition in zebrafish

描述（由申请人提供）：我们目前对早期胚胎发育的大部分遗传学理解来自于设计用于识别合子突变的筛选。越来越明显的是，早期发育的大部分是独立于合子基因组的。在早期胚胎发生过程中，母体提供的mRNA和蛋白质对DNA复制、细胞分裂和模式形成至关重要。中囊胚过渡（MBT）是母系和合子发育程序之间的接口，它需要母系基因才能正常执行。在MBT时，卵裂期的细胞快速分裂减慢，合子基因的表达显著增加。

DESCRIPTION (provided by applicant): Much of our current genetic understanding of early embryonic development is derived from screens designed to identify zygotic mutations. It is becoming increasingly evident that much of early development is independent of the zygotic genome. Maternal supplies of mRNA and protein are critical for DNA replication, cell division, and patterning during early embryogenesis. The mid-blastula transition (MBT) is the interface between the maternal and zygotic developmental program, and it requires maternal genes for its proper execution. At the MBT, the rapid cell divisions of the cleavage period slow, and a major increase in zygotic gene expression ensues. This proposal will help elucidate the mechanisms involved in the progression of the MBT in vertebrates. It seeks to characterize a recently identified maternal-effect mutant, screeching halt (srh), which arrests development at the MBT in zebrafish. The proposed experiments will investigate the role of srh in checkpoint regulation, a process important to the MBT in both Drosophila and Xenopus. I will determine the molecular identity of the srh gene, which is likely a novel factor acting in the MBT. In addition, I will perform a maternal-effect mutagenesis screen to identify additional alleles of srh, as well as novel genes that also function at the MBT.