MOLECULAR AND CELLULAR BASIS OF LENS DEVELOPMENT

参与决定特定细胞命运的那些过程是 胚胎发生的基本方面。 在脊椎动物胚胎中， 组织相互作用，称为诱导相互作用， 各种细胞命运的决定。 我们的总体目标是 研究的重点是这些过程的分子和细胞基础。 脊椎动物透镜的发展已被证明是一个很好的系统，其中 研究这些事件，因为这个器官的发展是由 通过一系列特定的组织相互作用。 这个系统的成功 部分原因是它可以直接进行实验， 操纵，特别是在两栖动物胚胎中。 我们理解 脊椎动物透镜诱导中涉及的组织相互作用是 然而，广泛的，实际上对分子基础一无所知 对于透镜细胞测定过程，或信号分子 参与透镜感应。 这些问题是《公约》的主要重点， 目前的研究建议。 将努力查明 基因表达的特异性变化与 使用该方法的透镜细胞确定和分化的过程 两栖动物非洲爪蟾 很难分离出这些 基因直接来自微小的假定透镜外胚层组织， 早期发展。 爪蟾的晶状体会从幼虫中再生出来 角膜后，透镜删除，一个过程中的转分化。 在 这些基因在透镜再生过程中表达 应该与胚胎发育过程中表达的相同。 透镜形成。 透镜再生的现象将被用作 这是一种更方便的方法来分离参与以下过程的基因： 透镜细胞的确定和分化。 两个cDNA文库将在 由再生和非再生角膜制备。 特异性基因 透镜再生过程中的任何一个环节 差减杂交技术 一旦这些基因被分离出来， 在胚胎透镜发育过程中， 形成，并将进行具体的测试，以确定是否 这些基因在这一过程中起着积极的作用。 最后，这些基因 将用作指示透镜发育早期阶段的标记， 组织培养实验来检验特定的透镜 诱导相互作用在触发基因特异性变化中起作用 表情 此外，还将进行组织培养实验， 解决以前的研究提出的问题，这些研究表明， 神经嵴细胞的抑制作用在确定 头部外胚层中透镜分化的确切部位。 最后， 将进行实验以确定特定生长是否 在胚胎外胚层培养物中， 组织中 越来越多的证据表明，生长因子在 胚胎细胞决定的各个方面。

Those processes involved in the determination of specific cell fates are fundamental aspects of embryogenesis. In vertebrate embryos, specific tissue interactions, termed inductive interactions, play a major role in the determination of various cell fates. The general goal of our research is to the molecular and cellular basis of these processes. Vertebrate lens development has proved to be an excellent system in which to examine these events, since the development of this organ is triggered by a series of specific tissue inter-actions. The success of this system is due, in part, to its accessibility to direct experimental manipulation, particularly in amphibian embryos. Our understanding of the tissue interactions involved in vertebrate lens induction is extensive, however, virtually nothing is known about the molecular basis for the process of lens cell determination, or the signal molecules involved in lens induction. These issues are the main focus of the current research proposal. Efforts will be devoted to identifying specific changes in gene expression which are associated with the processes of lens cell determination and differentiation using the amphibian Xenopus laevis. It would be very difficult to isolate these genes directly from minute presumptive lens ectodermal tissues during early development. In Xenopus, lenses will regenerate from the larval cornea following lens removal, a process of transdifferentiation. At some level, those genes expressed during the process of lens regeneration should be the same as those expressed during the process of embryonic lens formation. The phenomenon of lens regeneration, will be utilized as a more convenient means to isolate genes involved in the processes of lens cell determination and differentiation. Two cDNA libraries will be prepared from regenerating and non-regenerating corneas. Genes specific to the process of lens regeneration will be isolated using the technique of subtractive hybridization. Once these genes are isolated, their expression will be studied during the process of embryonic lens formation, and specific tests will be conducted to determine whether these genes play an active role in this process. Finally, these genes will be used as markers indicative of early stages of lens development in tissue culture experiments to examine the role that specific lens inductive interactions play in triggering specific changes in gene expression. In addition, tissue culture experiments will be conducted to address questions raised by previous studies, which suggest that inhibitory effects of neural crest cells play a role in pinpointing the exact site of lens differentiation in head ectoderm. Finally, experiments will be performed to determine whether specific growth factors can elicit lens formation in cultures of embryonic ectodermal tissues. There is growing evidence that growth factors play a role in various aspects of embryonic cell determination.