GENE EXPRESSION IN EARLY EMBRYONIC DEVELOPMENT

早期组蛋白基因在发育过程中的表达模式 海胆胚胎的特征是转录水平很高 从16~200细胞期，然后逐渐减弱转录， 500细胞间充质细胞囊胚后的周转和停止表达 舞台。这些组蛋白基因表达变化的调控，以及 一些非组蛋白染色质蛋白基因表达的描述， 是拟议研究的重点。 细胞质对基因表达的影响将通过融合来研究 显示不同组蛋白基因表达模式的胚胎分裂球， 而细胞质mRNA的转录水平和持久性将是 通过核酸杂交研究了生成的异核体，在 SITE。银杏叶提取物对核DNA/胞浆比值的影响 多精母细胞和多种抑制物对建立高信使核糖核酸的影响 将研究合成速度。早期组蛋白基因表达的终止 胚胎中的合成，其中细胞分裂和DNA合成 被禁止的也将被研究。组蛋白基因的径流转录 将进行研究以澄清聚合酶II基因的性质 在不同发展阶段的相互作用。 一些非组蛋白染色质蛋白的合成水平也很高。 在卵裂过程中。将尝试分离编码基因的cDNA克隆 其中一些蛋白质，以及这些序列的结构和表达 将被研究并与组蛋白基因进行比较。 这些研究应该有助于我们理解基因是如何 在正常和非正常发育期间打开和关闭。

The pattern of expression of the "early" histone genes during development of sea urchin embryos is characterized by a high level of transcription from the 16 to 200 cell stage, followed by diminishing transcription, mRNA turnover and cessation of expression after the 500 cell mesenchyme blastula stage. The regulation of changes in expression of these histone genes, and the description of expression of some non-histone chromatin protein genes, is the focal point of the proposed research. The influence of cytoplasm on gene expression will be studied by fusion of embryo blastomeres that display different modes of histone gene expression, and the level of transcription and persistence of cytoplasmic mRNA will be studied in the resultant heterokaryons by nucleic acid hybridization, in situ. The influence of altering the nueclear DNA/cytoplasmic rations by polyspermy and various inhibitors on the establishment of high mRNA synthesis rates will be studied. The cessation of early histone mRNA synthesis in embryos in which cell division and DNA synthesis have been inhibited will also be studied. The run-off transcription of histone genes will be studied in order to clarify the nature of the polymerase II-gene interaction at different stages of development. Some non-histone chromatin proteins are also synthesized at a high level during cleavage. Attempts will be made to isolate cDNA clones encoding some of these proteins, and the structure and expression of these sequences will be studied and compared to the histone genes. These studies should contribute to our understanding of how genes are turned on and off during normal and abnormal development.