MULTIGENE FAMILIES: STRUCTURE, EXPRESSION AND EVOLUTION

该项目的长期目标是了解 一个复杂的发展过程是如何通过综合的 大量基因的表达。 无法整合表达式 各种结构基因的基础是各种人类 发育缺陷 本研究选择的模型系统是 由单层卵泡细胞产生绒毛膜（蛋壳） 家蚕卵母细胞的成熟过程。 在这些 细胞的100多个绒毛膜蛋白质的合成遵循一个精确的时间 对应于特定mRNA产生程序的模式。 一个有用 这个系统的一个特点是所有的绒毛膜基因都紧密地聚集在 一个染色体的一小段。 据估计，这一地区的面积 是700块。 重组克隆上的整个基因座的回收（500 其中kb已经完成）以及详细的表征 的基因，将提供一个难得的机会，以跟踪 一个复杂的发展过程的演变，以及提供 为旨在了解轨迹如何协调 监管. 我们对基因调控的研究将涉及两个主要方面： 方法。 首先，利用同步的细胞群， 从蚕蛾卵巢解剖，我们将检查结构 细胞核内的绒毛膜基因的变化之前和期间， 表情 这些结构变化将通过确定 基因对DNA酶I的可及性。 这些实验解决了 基因如何在细胞核中标记的重要问题 后续表达。 其次，我们将确定绒毛膜位点是否 被分成环状的染色体区域。 这种循环的证据将 如果发现绒毛膜位点的片段与 与核基质，一个复杂的蛋白质网络在细胞核内。 使用在绒毛膜基因座内含有断裂点的突变 将非常有助于确定这种功能的作用， 假定的附着位点。

The long-term objective of this project is to obtain an understanding of how an elaborate developmental process is accomplished by the integrated expression of a large number of genes. Failure to integrate the expression of various structural genes is the basis for a variety of human developmental defects. The model system chosen for this study is the production of the chorion (eggshell) by the monolayer of follicle cells surrounding the maturing oocyte of the silkmoth, Bombyx mori. In these cells the synthesis of over 100 chorion proteins follows a precise temporal pattern corresponding to a program of specific mRNA production. One useful property of this system is that all chorion genes are tightly clustered on a small segment of one chromosome. The size of this region is estimated to be 700 kilobases. Recovery of the entire locus on recombinant clones (500 kb of which is already accomplished) along with detailed characterizations of the genes encountered, will provide a rare opportunity to trace the evolution of a complex developmental process, as well as provide the groundwork for studies designed to understand how the locus is coordinately regulated. Our study of gene regulation will involve two major approaches. First, utilizing the synchronous populations of cells that can be dissected from the silkmoth ovary, we will examine the structural changes of the chorion genes within the nucleus prior to and during their expression. These structural changes will be monitored by determining the accessibility of the genes to DNase I digestions. Such experiments address the important question of how genes are marked in the nucleus for subsequent expression. Second, we will determine whether the chorion locus is divided into looped chromosomal domains. Evidence for such loops will be obtained by if segments of the chorion locus are found to be associated with the nuclear matrix, an elaborate protein network within the nucleus. The use of mutations containing breakage points within the chorion locus will be extremely helpful in determining the functional role of such putative attachment sites.