CELL LINEAGE AND SEGMENTATION IN LEECH NERVOUS SYSTEM

这个项目的长期目标是阐明细胞和分子 发展机制。这是一项基础研究， 理解并最终改善遗传和环境的 诱发的发育障碍和未来生物医学的培训 健康研究人员。拟议研究的理由如下： 越来越清楚的是，与许多代谢和结构 蛋白质，许多发育调节蛋白也表现出高度的 进化上的保守，所以这些基因的同源物， 主要是通过遗传技术在果蝇中发现， 和其他无脊椎动物。了解这些基因如何 我们的工作是了解它们的胚胎表达和发育 对单个细胞的影响取决于与其他细胞的相互作用。 但是在果蝇和脊椎动物的胚胎中， 由于技术上的困难， 如细胞体积小，数量多，培养困难， 胚胎，以及（在果蝇中）早期发育涉及 合胞胚盘期，因此许多早期事件发生在一个 单个细胞无法被识别或检查的环境。 幸运的是，我们可以进行这种细胞水平的发育研究， 调节基因在水蛭中相对容易，因为在水蛭胚胎中， 单独鉴定的细胞可用于实验操作 在胚胎和成年人的神经系统中都有。 该项目的具体目标如下： l）继续鉴定水蛭基因ht-en的正常表达 （果蝇分节基因的同源物， 当前的兴趣是， 与胚胎中和/或胚胎中的特定细胞表型相关， 神经系统）; 2)在选择性消融细胞后寻找细胞命运的变化， express ht-en; 3)寻找ht-en特异性错表达后细胞命运的变化; 4)以表征其他分段的水蛭同源物的表达 基因，如肘肌m. interruptus-显性，并测试是否存在 表达这些基因的细胞和 表达ht-en。

The long term goal of this project is to elucidate cellular and molecular mechanisms of development. This is basic research that will contribute to the understanding and eventual amelioration of genetic and environmentally induced developmental disorders and to the training of future biomedical health researchers. The rationale for the proposed research is as follows: It is increasingly clear that, as with many metabolic and structural proteins, many developmental regulatory proteins also show a high degree of evolutionary conservation, so that homologs of these genes, identified mainly by genetic techniques in Drosophila, can be identified in vertebrate and other invertebrates. An important part of understanding how these genes work is to understand how their embryonic expression and developmental effects on individual cells are governed by interactions with other cells. But in Drosophila and vertebrate embryos it is difficult to study development at the level of single cells because of technical difficulties such as the small size and large numbers of cells, difficulty in culturing the embryos, and (in Drosophila) the fact that early development involves a syncytial blastoderm stage, so that many early events occur in an environment in which individual cells cannot be identified or examined. Fortunately, we can carry out such cell-level studies of developmental regulatory genes in leech with relative ease, because in leech embryos, individually identified cells are accessible to experimental manipulations both in the embryo and in the adult nervous system. The specific aims of this project are as follows: l) to continue characterizing the normal expression of the leech gene ht-en (a homolog of the Drosophila segmentation gene engrailed; the question of immediate interest is whether expression of engrailed-class genes is associated with particular cell phenotypes in the embryo and/or in the nervous system); 2) to look for cell fate changes after selective ablation of cells that express ht-en; 3) to look for cell fate changes after specific mis-expression of ht-en; 4) to characterize the expression of leech homologs of other segmentation genes, such as cubitus m.interruptus-Dominant and to test for the presence of interactions among the cells expressing these genes and the cells expressing ht-en.