MOLECULAR GENETICS OF GENE DOSAGE EFFECTS

基因剂量的改变会导致严重的基因紊乱 生物体的发育计划，但对 基因剂量效应的分子遗传学基础。我们的实验室研究 果蝇三致死基因(TPL)作为理解模型的研究 基因剂量效应。Tpl是已知的唯一致死的遗传位点。 一式三份。它也是半致命性的。动物与 三个拷贝或一个拷贝的TPL作为晚期胚胎或早期第一个死亡 幼虫，没有明显的肉眼形态缺陷。第三方物流是一种 复杂的轨迹，可能由冗余信息组成，因为点 消除其功能的突变从未被获得过。现在 TPL区克隆接近完成，重排断裂点 将在地图上定位，转录区域将被识别，以及 将选择一个或多个第三方物流候选基因进行进一步分析。 然后将对这些候选人进行种系和体细胞研究 转化实验作为检测TPL功能的方法。 因改变而死亡的胚胎的发育表型 第三方物流的剂量，也将详细审查，特别强调 细胞死亡发生的模式。因为总的发展 没有发现异常，看起来很可能是第三方物流参与了一些 基本的细胞功能，以及发生的细胞死亡模式 将使我们对缺陷的性质有更深入的了解。有丝分裂 重组还将用于产生细胞的体细胞克隆 携带改变的TPL剂量，这将揭示TPL的效果是否 细胞是自主的，如果有发育阶段，或组织 对TPL非整倍体不敏感。 在附近的一个基因座SU(TPL)上也有突变，这有效地 抑制TPL的三致死表型，但不抑制单致死表型。 利用SU(TPL)中的这些突变，以及我们将产生的回复变种， 我们将克隆该基因，并研究其与第三方物流的相互作用。

Alterations in gene dosage cause serious perturbations in the developmental program of organisms, yet very little is known about the molecular genetic basis of gene dosage effects. Our laboratory studies the Triplo-lethal locus of Drosophila (Tpl)as a model for understanding gene dosage effects. Tpl is the only genetic locus known that is lethal when present in three copies. It is also haplo-lethal. Animals with either three copies or one copy of Tpl die as late embryos or early first instar larvae, with no obvious gross morphological defects. Tpl is a complex locus, and may consist of redundant information, since point mutations that eliminate its function have never been obtained. Now that cloning of the Tpl region is nearly complete, rearrangement breakpoints will be located on the map, transcribed regions will be identified, and a candidate gene or genes for Tpl will be chosen for further analysis. These candidates will then be studied by germ-line and somatic transformation experiments as an assay for Tpl function. The developmental phenotype of embryos who are dying because of altered Tpl dosage, will also be examined in detail, with particular emphasis on the pattern of cell death which occurs. Since gross developmental anomalies are not seen, it seems probable that Tpl is involved in some fundamental cellular function, and the pattern of cell death which occurs will give us insights into the nature of the defect. Mitotic recombination will also be used to generate somatic clones of cells carrying altered Tpl dosage, which will reveal whether the effects of Tpl are cell autonomous, and if there are developmental stages, or tissues that are not sensitive to Tpl aneuploidy. There are also mutations in a nearby locus, Su(Tpl), which efficiently suppress the triplo-lethal but not the haplo-lethal phenotype of Tpl. Using these mutations in Su(Tpl), and revertants that we will generate, we will clone the locus, and study its interaction with Tpl.