HERITABILITY OF EMBRYONIC RADIOSENSITIVE TARGETS

嵌合体测定是用于检测体内暴露的 哺乳动物的生殖细胞受到电离辐射。这种暴露导致 在培养的小鼠中表达的细胞增殖不利 植入前胚胎在试验中，来自未暴露的4细胞胚胎 父母与来自暴露的雄性或雌性的4细胞胚胎配对 父母形成聚合嵌合体。该测定的终点是 “增殖比”，其是由细胞增殖因子贡献的细胞数量。 实验伴侣胚胎除以细胞总数 包含2-3轮细胞分裂后的嵌合体。比率 显著小于0.5，表明比实验伴侣胚胎 在嵌合体中表达细胞增殖劣势。后代细胞 目前，通过标记两个伴侣胚胎中的 在嵌合体之前用细胞质染料FITC对照配偶胚胎 建设然而，来自连续细胞分裂的标记稀释 排除了植入后分析和遗传性测试。 该项目的目标是开发一种“增强型”嵌合体检测方法， 研究亲代生殖细胞暴露对雄性的影响， 在植入和出生后仍然存在。第一个具体目标是 掺入可遗传非表达转基因细胞谱系标记， 替代嵌合体测定中的短期细胞谱系标记物FITC。的 第二个具体目标是使用我们的转基因细胞谱系标记， 嵌合体检测用于胎儿和出生后的植入后分析 发展第三个具体目标是应用嵌合体测定， 转基因细胞谱系标记物，用于亲本后的遗传性测试 暴露于生殖毒物。

The chimera assay is a sensitive test for detecting in vivo exposure of the mammalian germ cell to ionizing radiation. This exposure results in a cell proliferation disadvantage that is expressed in cultured mouse preimplantation embryos. In the assay, 4-cell embryos from non-exposed parents are paired with 4-cell embryos from either exposed male or female parents to form aggregation chimeras. The assay's endpoint is a "proliferation ratio", which is the number of cells contributed by the experimental partner embryo divided by the total number of cells comprising a chimera after 2-3 rounds of cell division. Ratios significantly less than 0.5 indicate than an experimental partner embryo expressed a cell proliferation disadvantage in the chimera. Progeny cells from the two partner embryos are currently distinguished by labelling the control partner embryo with the cytoplasmic dye FITC prior to chimera construction. However, label dilution from successive cell divisions precludes postimplantation analyses and heritability tests. This project's objective is to develop an 'enhanced' chimera assay to examine the effects of parental germ cell exposure in the male that persist beyond implantation and birth. Our First Specific Aim is to incorporate a heritable non-expressing transgenic cell lineage marker to replace the short-term cell lineage marker FITC in the chimera assay. The Second Specific Aim is to use our transgenic cell lineage marker to extend the chimera assay into postimplantation analyses of fetal and postnatal development. The Third Specific Aim is to apply the chimera assay with the transgenic cell lineage marker for heritability testing after parental exposure to reproductive toxicants.