GERM CELLS--DNA REPAIR, MUTATION, & ENVIRONMENTAL AGENTS

描述：生殖系突变可以对人类健康产生重大影响 对后代产生衰弱的影响据估计 5%的活产后代会有遗传疾病。其中，20%是 是由于生殖细胞的新生突变。从遗传学的角度来看，生殖细胞 与体细胞有很大的不同，因为它们携带的DNA 下一代的有机体，而不仅仅是下一个女儿 cell.似乎合理的假设是保护细菌的完整性- 线DNA将提供生存优势。值得注意的是，睾丸中 lacI转基因小鼠组织中的突变频率。照经上所 可以合理地推测，多种保障机制可能 进化出了这种组织类型提出了一种方法来测试 假设调节DNA修复途径， 重要的是确定自发突变频率在精子发生 细胞首先，将在细胞中测定各种DNA修复活性， 定义精子发生的阶段，以确定DNA修复途径， 在确定自发突变频率方面可能很重要， 生精细胞基于这些结果，转基因小鼠， 适当途径中的活性降低将加倍 通过与携带lacI转基因的小鼠杂交获得转基因。Laci 然后测量特定生精细胞的突变频率 类型，以确认哪些DNA修复途径在 确定自发突变频率。在下一阶段，lacI和 lacZ转基因雄性小鼠将用环境显著的 基因毒素电离辐射随后，突变频率将 在生精细胞的离散群体中测量， 确定：1）生精细胞之间是否存在差异突变 2）如果突变频率与DNA修复活动相关 在第一阶段测量。这项研究将促进对 涉及生殖细胞突变的基本机制。

DESCRIPTION: Germline mutations can impact substantially on human health by having debilitating effects on ensuing offspring. It is estimated that 5% of liveborn offspring will have a genetic disorder. Of these, 20% are due to germline de novo mutations. From a genetic perspective, germ cells are profoundly different from somatic cells because they carry the DNA for the next generation of the organism, not simply for the next daughter cell. It seems logical to assume that safeguarding the integrity of germ- line DNA would provide survival advantages. Notably, testis has the lowest mutation frequency among tissues in lacI transgenic mice. Thus, it is reasonable to speculate that multiple safeguarding mechanisms may have evolved with this tissue type. An approach is presented to test the hypothesis that modulation of DNA repair pathways that are potentially important in determining spontaneous mutation frequencies in spermatogenic cells. First, various DNA repair activities will be assayed in cells at defined stages of spermatogenesis to identify DNA repair pathways that are potentially important in determining spontaneous mutation frequencies in spermatogenic cells. Based on these results, transgenic mice that have reduced activity in an appropriate pathway(s) will be made doubly transgenic by crossing with mice carrying the lacI transgene. lacI mutation frequencies will then be measured for specific spermatogenic cell types to confirm which DNA repair pathways play a fundamental role in determining spontaneous mutation frequencies. In the next phase, lacI and lacZ transgenic male mice will treated with an environmentally significant genotoxin, ionizing radiation. Subsequently mutation frequencies will be measured in discrete populations of spermatogenic cells to directly determine: 1) if there is a differential mutability among spermatogenic cells and 2) if mutation frequencies correlate with DNA repair activities measured in the first phase. This study will advance an understanding of the fundamental mechanisms involved in mutagenesis in germ cells.