RADIOSENSITIVE TARGET IN THE EARLY MOUSE EMBRYO

人们越来越关注检测早期细胞凋亡的能力， 可能指示胚胎和配子内损伤的变化 来自非常低水平的环境生殖危害，如 低水平电离辐射。 这个提案用的是小说，很敏感 辐射效应显示为细胞凋亡的测定， 植入前胚胎的增殖。 该试验使用小鼠胚胎 聚集嵌合体，并已证明能够检测0.01 - 0.05戈伊（1至 5拉德）给予体外胚胎或精子产生的胚胎 在体内照射。 我们的主要目标是确定 分析反映了核内或核外放射敏感靶点， 配子和植入前胚胎。 放射源将是氚，附着在载体（胸苷）上 将辐射集中到原子核，或者，（水）， 提供均匀的辐射。 第三载体（聚乙二醇， 不会进入细胞）将用于体外研究以限制 照射质膜/细胞皮层以检验假设 这可能是辐射敏感的目标， 在嵌合体测定中的细胞增殖中。 为实现我们的主要目标，将进行三项不同的研究。 第一个是体外研究， 或核外（质膜/细胞皮质？）用于小区 在嵌合体测定中通过切割胚胎显示的增殖降低。 第二个是体内研究，提出了卵母细胞的3个问题：1） 卵母细胞的辐射暴露是否会导致 在嵌合体试验中胚胎的缺点？2)如果是， 放射敏感靶核？3)卵母细胞的敏感性 辐射敏感目标的性质-在不同时期不同， 卵母细胞发育？ 最后一项研究也是在体内进行的， X射线照射在精子发生中观察到的放射敏感靶点是 核武器 这些研究的结果对于确定是否 这种与辐射相关的细胞增殖减少表明 遗传性基因变化。

There is a growing concern over the ability to detect early cellular changes that may be indicative of damage within embryos and gametes incurred from very low levels of environmental reproductive hazards such as low-level ionizing radiation. This proposal uses a novel, very sensitive assay in which effects of radiation are revealed as a decrease in cellular proliferation in preimplantation embryos. The assay utilizes mouse embryo aggregation chimeras and has the proven ability to detect .01-.05 Gy (1 to 5 rad) given to embryos in vitro or with embryos produced from sperm irradiated in vivo. Our primary objective is to determine whether the assay is reflecting a nuclear or extra nuclear radiosensitive target in gametes and preimplantation embryos. The radiation source will be tritium, attached to a carrier (thymidine) that will concentrate irradiation to the nucleus, or, (water) that will deliver a uniform irradiation. A third carrier (polyethylene glycol, which does not enter cells) will be used in the in vitro studies to limit irradiation to the plasma membrane/cytocortex to examine the hypothesis that this might be the radiosensitive target responsible for the decrease in cellular proliferation in the chimera assay. Three different studies will be undertaken to attain our primary objective. The first one is an in vitro study that asks whether the target is nuclear or extra-nuclear (the plasma membrane/cytocortex?) for the cell proliferation decrease exhibited by cleaving embryos in the chimera assay. The second one is an in vivo study that asks 3 questions of the oocyte: 1) will a radiation exposure to the oocyte result in a proliferative disadvantage of the embryo in the chimera assay?; 2) if so, is the radiosensitive target nuclear?; 3) will the sensitivity of the oocyte--and the nature of the radiosensitive target-differ during different periods of oocyte development? The last study is also in vivo and asks whether the radiosensitive target observed with X-irradiation in spermatogenesis is nuclear. The results of these studies are crucial for determining whether this radiation-associated decrease in cellular proliferation is indicative of heritable genetic change.