HERITABILITY OF EMBRYONIC RADIOSENSITIVE TARGETS

使用杂交的CD1小鼠品系的研究表明，父本 交配前6-7周对F0小鼠进行照射 F1、F2胚胎细胞增殖有明显变化。这些 变化被揭示为细胞增殖的竞争劣势 在嵌合体分析中，当受影响的胚胎与正常的 聚合嵌合体中的胚胎。该效果被传递给F1和 F2胚胎接受1.0Gy137Cs伽马射线，不会在 F0、F1和F2代，并与 体重、选定信号转导基础水平的变化 蛋白激酶活性和P53蛋白基础水平升高 在F3的后代中。在这个项目中，我们问的是基因是否 父性F0的这些可遗传后果背后的变化 辐射更有可能减少、保持不变或 随着一代又一代的成长。 我的具体目标是确定竞争性细胞 在以下情况下，后代的扩散劣势将有所不同 外交的CD1株被同基因的C57BL/6株取代。 我们将使用C57BL/6男性进行父性F0照射，以减少 表现力的差异，并将评估F1，F2和F3 在嵌合体分析中的后代。如果竞争性细胞增殖 劣势不会世世代代减少，我们会 假设导致这种可遗传效应的基因变化 在几代人之间是不稳定的。 具体目标二将是检验核变化的假设 导致竞争性细胞增殖劣势包括“DNA 我们将照射一个纯合子的父亲的F0队列 一种可能(间接)导致DNA修复减少的P53零突变。 如果这一假设是正确的，我们预计P53零突变 增加后代的竞争性细胞增殖劣势 父亲的F0辐射。 具体目标三将是检验核变化的假设 导致竞争性细胞增殖劣势的因素将增加 在世代之间产生连续更大的变化 相关的终点，包括蛋白激酶活性。这 结果将符合这样的假设，即这些可遗传 辐射父系生殖系的后果可能会被放大 由代代相传的基因组不稳定性造成。

Studies using the outbred CD1 mouse strain have shown that paternal irradiation of F0 mice six to seven weeks prior to mating causes significant changes in F1 and F2 embryonic cell proliferation. These changes are revealed as a competitive cell proliferation disadvantage in chimera assays when the affected embryo is paired with a normal embryo in an aggregation chimera. This effect is transmitted to F1 and F2 embryos for 1.0 Gy of 137Cs gamma rays, does not decrease between the F0, F1 and F2 generations, and correlates with significant decreases in body weights, changes in basal levels of selected signal transduction protein kinase activities and in elevated basal levels of p53 protein in the F3 offspring. In this project, we ask whether the genetic changes underlying these heritable consequences of paternal F0 irradiation are more likely to decrease, remain unchanged, or to increase with successive generations. Specific Aim I will be to determine whether competitive cell proliferation disadvantage in successive generations will differ when the outbred CD1 strain is replaced with the syngenic C57BL/6 strain. We will conduct a paternal F0 irradiation using C57BL/6 males to reduce differences in expressivity and will evaluate the F1, F2 and F3 offspring in chimera assays. If competitive cell proliferation disadvantage does not decrease with successive generations we will hypothesize that the genetic changes that cause this heritable effect are unstable across generations. Specific Aim II will be to test the hypothesis that the nuclear changes that cause competitive cell proliferation disadvantage include "DNA damage". We will irradiate a paternal F0 cohort that is homozygous for a p53 null mutation which may (indirectly) result in reduced DNA repair. If this hypothesis is correct, we expect the p53 null mutation to increase competitive cell proliferation disadvantage in the offspring of paternal F0 irradiation. Specific Aim III will be to test the hypothesis that the nuclear changes that cause competitive cell proliferation disadvantage will increase in number across generations to produce successively greater changes in correlative endpoints, including protein kinase activities. This outcome would agree with the hypothesis that these heritable consequences of irradiating the paternal germline may become amplified by genomic instability across generations.