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遗传理解大多来自于旨在鉴定合子突变的筛选。越来越明显的是，许多早期发育是独立于合子基因组的。母体提供的mRNA和蛋白质对早期胚胎发育过程中的DNA复制、细胞分裂和图案形成至关重要。中期囊胚转换（MBT）是母亲和合子发育程序之间的接口，它需要母亲的基因来正确执行。在MBT时，卵裂期的快速细胞分裂减慢，合子基因表达增强。 这一建议将有助于阐明脊椎动物中MBT进展的机制。它旨在描述最近发现的母体效应突变体，尖叫停止（srh），这逮捕了在斑马鱼的MBT的发展。拟议的实验将调查srh在检查点调节中的作用，这是一个对果蝇和非洲爪蟾的MBT很重要的过程。我将确定srh基因的分子身份，这可能是一个新的因素在MBT中发挥作用。此外，我将进行母体效应诱变筛选，以确定其他等位基因的srh，以及新的基因，也在MBT功能。

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.