MOLECULAR GENETICS OF GENE DOSAGE EFFECTS

基因剂量的改变会引起细胞内 生物体的发育程序，但很少有人知道 基因剂量效应的分子遗传学基础。 实验室研究 果蝇三倍致死基因座（Tpl）作为理解 基因剂量效应 Tpl是已知的唯一致命的基因位点 当以三份副本存在时。 它也是单倍致命的。动物 Tpl的三个拷贝或一个拷贝作为晚期胚胎或早期胚胎首先死亡 龄幼虫，没有明显的大体形态缺陷。 TPL是一个 复杂的轨迹，并可能包括冗余信息，因为点 从未获得消除其功能的突变。 现在 Tpl区域的克隆几乎完成，重排断裂点 将位于地图上，转录区域将被识别， 选择Tpl的一个或多个候选基因用于进一步分析。 这些候选人将通过生殖系和体细胞研究， 转化实验作为Tpl功能的测定。 胚胎的发育表型，这些胚胎由于改变了 还将详细检查TPL剂量，特别强调 细胞死亡的模式。 由于总体发展 异常没有看到，它似乎可能是TPL参与了一些 基本的细胞功能，以及细胞死亡的模式， 能让我们深入了解缺陷的本质 丝分裂 重组也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的作用是否 是细胞自主的，如果有不同的发育阶段， 对Tpl非整倍性不敏感的细胞。 附近的基因座Su（Tpl）也有突变， 抑制Tpl的三倍致死表型，但不抑制Tpl的单倍致死表型。 利用Su（Tpl）中的这些突变，以及我们将产生的回复突变体， 我们将克隆该位点，并研究其与Tpl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.