CYTOGENETIC ANALYSIS OF MUTAGEN-SENSITIVE MUTANTS

果蝇mei-9和mei-41基因突变株 对多种诱变剂敏感，有切除缺陷和 分别是复制后修复和减数分裂重组，并有 脆弱的染色体。Mei-41基因是EMS和P元件的热点 插入突变并显示高频率的等位基因间减数分裂 重组，表明该基因相对较大。要确认 这一假说，并更好地理解 控制DNA修复的基因，这些基因已经用转座子克隆出来 标记，并正在进行分子表征。梅-41的文字记录是 2.2千碱基对的长度，分布在14-28千碱基对的 基因组DNA。MEI-9尚未被克隆，因为多次重复 邻近区域的序列使分子行走变得困难。另一个 基因Mus3O8已被鉴定为基于对 诱变剂，看起来类似于人类的范可尼贫血 与染色体不稳定和发病率增加相关的疾病 白血病的症状。该基因也正在被克隆。

Mutants of the mei-9 and mei-41 genes of Drosophila melanogaster are sensitive to a variety of mutagenic agents, defective in excision and postreplication repair respectively, and meiotic recombination, and have fragile chromosomes. The mei-41 gene is a hot spot for EMS and P-element insertion mutagenesis and shows a high frequency of interallelic meiotic recombination, suggesting that the gene is relatively large. To confirm this hypothesis and to better understand the structure and regulation of genes controlling DNA repair, these genes have been cloned using transposon tagging and are being characterized molecularly. The mei-41 transcript is 2.2 kilobase pairs in length and distributed over 14-28 kilobase pairs of genomic DNA. The mei-9 has not yet been cloned because multiple repeated sequences in the immediate region make molecular walking difficult. Another gene, mus3O8, has been identified based on increased sensitivity to mutagens and appears to be analogous with Fanconi's anemia, a human disorder associated with chromosome instability and an increased incidence of leukemia. This gene is also being cloned.