CHROMATIN STRUCTURE AND GENE REGULATION OF ROSY LOCUS

染色质结构与基因活性有关， 活性染色质比非活性染色质对DNA酶I更敏感。 在 此外，在基因的5'侧翼区存在位点， 当基因活跃时对DNA酶I极其敏感。 无背书或 这些位点的碱基变化与以下因素的缺乏或减少有关： 基因表达。 我们建议研究这种核酸酶的敏感性在玫瑰位点的 果蝇 玫瑰色的基因座含有结构基因 黄嘌呤脱氢酶（XDH）及其DNA已被克隆。 其表达 是受发育调控的组织特异性的 有几 对照突变体，包括异染色质位置效应突变体 in this locus轨迹. 我们已经确定了控制区的碱基变化， 通过DNA测序发现了两个产量不足的突变体。 我们希望分析野生型中该位点的DNA酶I超敏性， 类型和对照突变体。 我们观察到的任何变化 与已知的DNA序列和XDH表达。 这些信息 也可用于该基因座中的定向诱变工作。 与 异染色质位置效应突变体，我们将研究，此外， 活性染色质的一般DNA酶I敏感性。 我们假设 异染色质位置效应是由于异染色质浓缩， 以这种方式，真核染色质中的相邻基因表现出降低的表达。 这种浓缩的染色质可能更具DNA酶抗性。 我们与W. Bender's和A. Chovnick的 实验室正在规划中。 希望我们共同努力， 有助于理解XDH表达的控制， 调控

Chromatin structure is related to gene activity in that transcriptionally active chromatin is more susceptible to DNAase I than inactive one. In addition, there are sites at 5' flanking region of a gene which are extremely sensitive to DNAase I when the gene is active. Absence of, or base changes at these sites is correlated with the absence or reduction of gene expression. We propose to study such nuclease sensitivity in the rosy locus of Drosophila melanogaster. The rosy locus contains the structural gene of xanthine dehydrogenase (XDH) and its DNA has been cloned. Its expression is developmentally regulated and tissue specific. There are several control mutants including heterochromatic position effect mutants available in this locus. We have identified base changes in the control region of two underproducer mutants by DNA sequencing. We wish to analyze the DNAase I hypersensitivity of this locus in wild types and control mutants. Any variations we observe will be correlated with the known DNA sequence and the XDH expression. These informations should also be useful for directed mutagenesis work in this locus. With the heterochromatic position effect mutants, we will examine, in addition, a general DNAase I sensitivity of active chromatin. We hypothesize that heterochromatic position effects are due to heterochromatin condensation in such a way that an adjacent gene in eucromatin shows a reduced expression. Such condensed chromatin could be more DNAase resistant. Collaborative efforts of our project with W. Bender's and A. Chovnick's laboratories are planned. It is hoped that our joint efforts will contribute in understanding the control of the XDH expression and regulation.