HIGH RESOLUTION INTERPHASE CHROMOSOME STRUCTURE

这里提出的工作的总体目标是确定 两个特异体的完整三维间期染色体结构 黑腹果蝇的Notch和Engraded基因 它们在二倍体胚胎和二倍体胚胎中表达程序中的临界时间 幼虫多线染色体。这个项目的目的是确定 在果蝇的生命周期中，基因发生了什么结构变化 以及这些变化如何与基因表达的变化相关联。 由于越来越详细的分子和基因分析，它已经 越来越清楚，染色体环境可以对基因产生深远的影响 行为，可能是因为染色质结构对 表情。许多观察结果支持这一观点：1)不活跃的X 人类女性的染色体高度浓缩，这表明了一种相关性 染色体解缩和基因表达之间的关系。脆弱的X 综合症，主要在人类中引起智力迟缓和其他缺陷 雄性，被假设为不完全重新激活的结果 母系X染色体的一部分。2)部分的表达 当同源配对中断时，果蝇的基因会发生变化。3) 哺乳动物基因的整合拷贝的表达是位置敏感的，因为 是P元件介导的基因在果蝇中的插入。 高分辨率光学显微镜和原位杂交 结合分子技术将被用来确定 二倍体Notch基因座和嵌合基因的染色体结构 胚胎中的间期细胞，当基因沉默时和发病后 关于基因表达的。然后，相同的技术将结合使用 利用体外诱变和P-元件介导的种系转化 以确定哪些DNA序列是维持果蝇 基因结构。 在实现这些目标时，涉及正常状态的基本问题 染色体将会得到回答。此外，还将获得新的见解。 某些可转座的DNA序列选择 阻断基因并诱导突变。

The overall objective of the work proposed here is to determine the complete 3-dimensional interphase chromosome structure of two specific genes, the Notch and engrailed genes of Drosophila melanogaster, at several critical times in their expression programs in diploid embryonic and in larval polytene chromosomes. The purpose of this project is to determine what structural changes occur in the genes during the Drosophila life cycle and how these changes correlate to changes in gene expression. As a result of increasingly detailed molecular and genetic analysis, it has become clear that chromosomal context can have profound effects on gene behavior, probably because of the influence of chromatin structure on expression. A number of observations support this idea: 1) The inactive X chromosome in human females is highly condensed, suggesting a correlation between chromosome decondensation and gene expression. The fragile X syndrome, causing mental retardation and other defects primarily in human males, has been hypothesized to result from incomplete reactivation of a portion of the maternally derived X chromosome. 2) The expression of some genes in Drosophila is altered when homologue pairing is interrupted. 3) Expression of integrated copies of mammalian genes is location sensitive as are P-element mediated gene insertions in Drosophila. High resolution optical microscopy and in situ hybridization, in conjunction with molecular techniques will be used to determine the chromosome structure of the Notch locus and the engrailed gene in diploid interphase cells in embryos, when the genes are silent and after the onset of gene expression. The same techniques will then be used in conjunction with in vitro mutagenesis and P-element mediated germline transformation of Drosophila to determine which DNA sequences are required to maintain the gene structure. In accomplishing these aims, basic questions concerning the state of normal chromosomes will be answered. In addition, new insights will be gained into the mechanism by which certain transposable DNA sequences choose to interrupt genes and induce mutations.