Rex-Induced Recombination in the Ribosomal DNA of Drosophila

9305846罗宾斯异染色质是真核生物基因组中的重要组成部分，具有许多或显著的特征。然而，几乎没有异色功能被鉴定出来。其中为数不多的是核糖体RNA基因(RDNA)和rex(核糖体交换)，这是一种母体效应的共生基因，在由Rex雌性产生的胚胎的早期有丝分裂中诱导rDNA重组。Rex现在已经被证明是位于rDNA阵列中的重复元件。在雷克斯诱导的交换部位，rDNA重复序列的缺失表明染色体断裂参与其中。在所有rDNA阵列中发现的一个插入序列的活性变体产生的内切酶可以是在所有rDNA阵列中发现的一个插入序列的活性变体的基础可以是REX的基础。对该系统的分析将继续在三个方面进行：1)REX性质和作用的分子和遗传学分析，2)利用REX诱导的重组快速定位rDNA阵列，3)重组rDNA阵列的性质分析。约30%的果蝇基因组是构成异染色质，但人们对其结构和功能知之甚少。REX可以提供一种工具来更多地了解果蝇的这些染色体区域，然后可以将这些知识外推到其他无法进行此类实验的真核生物中。***

9305846 Robbins Heterochromatin is a substantial fraction of every eukaryotic genome and has a number or remarkable characteristics. Nevertheless, few heterochromatic functions have been identified. Among those few are the ribosomal RNA genes (rDNA)and Rex (Ribosomal exchange), a maternal-effect cominant that induces rDNA recombination during early mitotic divisions in embryos produced by Rex females. Rex has now been shown to be a repeated element located within the rDNA array. Deletion of rDNA repeats at the sites of Rex induced exchange suggests that chromosome breakage is involved. An endonuclease produced by an active variant of one of the insertion sequences found in all rDNA arrays could be the basis of active variant of one of the insertion sequences found in all rDNA arrays could be the basis of Rex. Analysis of this system will continue in three areas: 1) Molecular and genetic analysis of the nature and action of Rex, 2) Rapid mapping of rDNA arrays by use of Rex-induced recombination, 3) Analysis of the properties of recombinant rDNA arrays. %%% Roughly thirty percent of the genome of the fruit fly is constitutive heterochromatin and yet little is known about either its structure or function. Rex can provide a tool for learning more about these chromosomal regions in the fruit fly, which knowledge can be then extrapolated to other eukaryotic organisms in which these type of experiments cannot be done. ***