ANALYSIS OF GENES EXPRESSED IN PREIMPLANTATION MOUSE EMBRYOS.

在过去的两年里，这笔资金帮助我们与欧洲和美国的许多优秀的研究人员进行了很大的互动，并与他们组织了非常富有成效的合作。该项目的长期目标是了解早期哺乳动物胚胎中基因表达的调控。该领域的主要障碍之一是难以获得大量实验材料，因此对过程的分子理解非常有限。为了克服这一障碍，我们决定通过分离小鼠早期胚胎中表达的基因开始合作研究。利用各种“最先进”的基因工程技术，我们能够从少量小鼠早期胚胎中构建cDNA文库。然后，我们建立了全载原位杂交技术，并分析了我们的几种新cdna在早期胚胎和各种小鼠组织中的表达模式。在更多的合作中，迄今为止最重要的发现来自对一个名为ssc - d的cDNA克隆的分析。对小鼠早期胚胎中SSEC-D转录本的分析表明，母系遗传的SSEC-D RNA物种在1-2细胞胚胎期逐渐显着延长，然后在2细胞后期变得缩短和降解。ssc - d RNA的链长延长似乎是由于在RNA的3'端添加了额外的聚A序列（300-400个核苷酸）。特别有趣的是，ssc -d转录本的这种动态变化独立于（RPase ii导向的）合子转录、DNA复制甚至受精。因此，ssc - d RNA的变化似乎反映了一个自主的母体程序，即使在受精后也继续发挥作用。我们目前正准备报告我们的新发现，并计划进一步扩展分析，以了解这一现象的生物学原因和影响。少

In the past two years, the fund from this grant helps us greatly to interact with many excellent researchers in Europe and in the US,and organize very fruitful collaboration with them.The long-term goal of the project was the understanding of regulation of gene expression in early mammalian embryos. One of the main obstacles in this field had been the difficulty in obtaining large quantity of experimental materials, and thus molecular understanding of the precess had been very limited.In order to circumvent this obstacle, we decided to begin the collaborative research by isolating genes that are expressed in mouse early embryos. With various "state-of-art" genetic engineering techniques, we were able to construct cDNA libraries from small amounts of mouse early embryos. We then established the whole-mount in situ hybridization technique, and analyzed expression patterns of our several novel cDNAs in early embryos as well as in various mouse tissues.Among many valuable outcomes of this … More collaboration, by far the most important findings came from the analyzes of one of the cDNA clones, called SSEC-D.Analyzes of the SSEC-D transcripts in early mouse embryos have revealed that the maternally inherited SSEC-D RNA species become significantly elongated in a stepwise fashion during the 1-2 cell embryonic stage, and then become shortened and degraded by the late 2-cell stage. The chain-length elongation of the SSEC-D RNA appears to be due to addition of extra poly A sequences (300-400 nucleotides) to the 3'-end of RNA.It is particularly intriguing that this dynamic changes of the SSEC-D transcripts are independent of (RPase II-directed) zygotic transcription, DNA replication, or even fertilization. It thus appears that the changes of the SSEC-D RNA reflect an autonomous maternal program, which continues to play roles even after fertilization. We are currently preparing to report our novel findings, and plan to extend further the analyzes to understand the biological causes and effects of this phenomenon. Less