GENETIC CONTROL OF MUTATION IN DROSOPHILA

工作总结：本研究旨在探讨果蝇DNA修复、染色体结构和突变之间的关系。 增加突变频率的突变（突变体）已在mu 2基因中鉴定并表征。 辐照过的卵母细胞染色体不能正常修复。 相反，受精后受精卵中断裂的染色体被新的端粒“覆盖”。 在相同条件下，辐照精子染色体可以正常修复。因此，似乎DNA本身在mu 2突变雌性中是活跃的，但卵母细胞染色体不适合修复。鉴于mu 2突变也增加有丝分裂重组，并且mu 2基因在有丝分裂活性体细胞中表达，预期MU 2蛋白也与体细胞染色体缔合。 mu 2基因序列与数据库中的任何其他基因没有很强的相似性。概念蛋白有三个核定位信号;一个螺旋-环-螺旋结构域邻近一个短的碱性区域，表明蛋白质和/或DNA结合活性;和一个BRCT（BRCA 1羧基末端）结构域，在许多DNA修复/重组/细胞周期控制蛋白中发现的蛋白质结合区域。该项目将于年底结束。

Summary of Work: This project is designed to determine the relationships among DNA repair, chromosome structure, and mutagenesis in Drosophila melanogaster. Mutations that increase the mutant frequency (mutators) have been identified in the mu2 gene and characterized. Irradiated oocyte chromosomes are not repaired properly. Instead, broken chromosomes are "capped" with a new telomere in the zygote after fertilization. Irradiated sperm chromosomes are repaired normally under the same conditions. Thus, it appears that DNA, per se, is active in mu2 mutant females, but the oocyte chromosomes are not amenable to repair. Given that mu2 mutations also increase mitotic recombination and the mu2 gene is expressed in mitotically active somatic cells, it is expected that the MU2 protein also associates with somatic chromosomes. The mu2 gene sequence does not have a strong resemblance to any other genes in the database. The conceptual protein has three nuclear localization signals; a helix-loop-helix domain adjacent to a short basic region, suggesting protein and/or DNA binding activity; and a BRCT (BRCA1 carboxy terminal) domain, a protein-binding region found in many DNA repair/recombination/cell cycle control proteins. The project will terminate at the end of the year.