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

描述：生殖系突变会对人类健康产生重大影响 通过对下一代产生衰弱作用。据估计， 5%的活着出生的后代会有遗传障碍。其中，20%是 由于新生的种系突变。从遗传学的角度来看，生殖细胞 与体细胞有很大的不同，因为它们携带着 有机体的下一代，不仅仅是为了下一个女儿 手机。似乎合乎逻辑的假设是，保护细菌的完整性- 品系DNA将提供生存优势。值得注意的是，睾丸具有最低的 LacI转基因小鼠组织间的突变频率。因此，它是 合理地推测多个保护机制可能具有 由这种组织类型进化而来。提出了一种测试该方法的方法 假设DNA修复途径的调制可能是 在生精过程中测定自发突变频率的重要性 细胞。首先，将在细胞中检测各种DNA修复活动 精子发生的明确阶段，以确定DNA修复途径 在确定自发性突变频率方面具有潜在的重要意义 生精细胞。基于这些结果，具有 适当途径的活动减少(S)将加倍 通过与携带LacI转基因的小鼠杂交进行转基因。Laci 然后将测量特定生精细胞的突变频率。 确认哪些DNA修复途径在其中发挥基础作用的类型 测定自发突变频率。在下一阶段，Laci和 LacZ转基因雄性小鼠将接受具有环境意义的 遗传毒素，电离辐射。随后，突变频率将是 在离散的生精细胞群中测量到直接 确定：1)在生精过程中是否存在差异突变 细胞和2)突变频率是否与DNA修复活动相关 在第一阶段进行了测量。这项研究将促进对 生殖细胞诱变的基本机制。

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.