RADIOSENSITIVE TARGET IN THE EARLY MOUSE EMBRYO

人们越来越关注检测早期细胞的能力 可能表明胚胎和配子内的损害的变化 由极低水平的环境生殖危害引起的，如 低水平的电离辐射。这项提议使用了一种新颖的、非常敏感的 辐射效应显示为细胞数量减少的一种化验方法 植入前胚胎的增殖。该试验利用小鼠胚胎 聚合嵌合体，并具有已被证明的检测0.01-0.05Gy1到0.05Gy1到0.05Gy值的能力 5 rad)用于体外胚胎或由精子产生的胚胎 体内照射过的。我们的主要目标是确定 化验是反映一个核或超核辐射敏感的靶点 配子和植入前胚胎。 放射源将是氚，附着在载体(胸苷)上 这将集中辐射到原子核，或者，(水)，这将 提供均匀的辐射。第三种载体(聚乙二醇，其 不进入细胞)将用于体外研究以限制 对质膜/细胞皮质的照射来验证这一假说 这可能是造成这种下降的辐射敏感目标 在嵌合体实验中的细胞增殖。 为了达到我们的主要目标，我们将进行三项不同的研究。 第一个是体外研究，询问目标是否为核 或核外(质膜/细胞皮质？)对于细胞而言 在嵌合体实验中，卵裂胚胎表现出增殖抑制。 第二个是活体研究，提出了3个关于卵母细胞的问题：1) 辐射暴露于卵母细胞是否会导致增殖剂 胚胎在嵌合体检测中的劣势？；2)如果是这样， 辐射敏感的核？；3)卵母细胞的敏感性--和 辐射敏感靶的性质-在不同的时期有所不同 卵母细胞发育？最后一项研究也是在活体内进行的，并询问 精子发生中X射线观察到的辐射敏感靶点 核武器。这些研究的结果对于确定 这种与辐射相关的细胞增殖减少是指示性的。 可遗传的基因变化。

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.