GENE EXPRESSION IN EARLY EMBRYONIC DEVELOPMENT

发育过程中“早期”组蛋白基因的表达模式 海胆胚胎的特点是高水平的转录 从16到200个细胞阶段，随后是转录减少，mRNA 500细胞间充质囊胚后的周转和表达停止 阶段 这些组蛋白基因表达变化的调节， 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 显示不同组蛋白基因表达模式的胚胎卵裂球， 细胞质mRNA的转录水平和持续性将被 通过核酸杂交在所得异核体中研究， 原地。 改变细胞核DNA/细胞质比值对细胞核DNA含量的影响 多精受精和各种抑制剂对建立高mRNA 将研究合成速率。 早期组蛋白mRNA的终止 在胚胎中，细胞分裂和DNA合成已经被 也将进行研究。 组蛋白基因的径流式转录 将进行研究，以澄清聚合酶II基因的性质， 不同发展阶段的互动。 一些非组蛋白染色质蛋白也高水平合成 在卵裂过程中。 将尝试分离cDNA克隆，其编码 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 在正常和异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.