VERTEBRATE MIDBRAIN AND LIMB DEVELOPMENT

将受精卵转变为完全发育的卵子 生物体是一个复杂的过程，其分子基础是 刚刚开始揭开面纱。重组人的最新进展 DNA方法学，加上强大的遗传和 胚胎学技术，已经导致了一种小的 起关键作用的调控基因的数量 协调脊椎动物胚胎的发育程序。 这项提议关注的是其中一种名为1MX-1a的基因。 1MX-1a的分子分析表明它是一种LIM-1 同源结构域转录因子，其功能是调节 其他尚未确定的基因产物的合成。1MX-1a是 在发育中的肢体细胞的离散子集中产生 中枢神经系统在其形成的早期阶段， 在任何明显的分化迹象出现之前。基于ITS 1MX-1a在鸡和小鼠胚胎中的表达模式 在规范中扮演主要监管角色，并 四肢和大脑中细胞命运的协调。为了定义 1MX-1a在肢体发育中的作用 中枢神经系统的中后脑区域，小鼠缺乏 这种基因将由胚胎干细胞产生。 技术。这些小鼠的发育将被研究。 使用各种分子和组织学方法来确定 由1MX-1a缺失引起的缺陷。此外，1MX-1a 将在鸡的正常边界之外表达 使用重组禽类病毒载体的胚胎。这一点的影响 手法对雏鸡中后脑发育的影响 将使用分子和解剖标记来确定区域 细胞的命运。最后，我们将研究1MX-1a的表达 在四肢和中后脑发育缺陷的小鼠中 确定1MX-1a是否可能参与了 这些致命的表型。预计这些研究将 极大地丰富了我们目前对脊椎动物的认识 发育机制。此外，产生的试剂 作为这项工作的结果，将促进未来旨在 定义特定的分子遗传过程，这些过程是 在动物胚胎发育过程中形状和形式的获得。 最后，这些研究直接关系到人类胚胎。 发展以来的发展机制，包括具体的 基因产物在所有脊椎动物中都很保守。 因此，假设这项工作可能 导致新的模式，旨在诊断和预防 四肢和大脑发育异常。

The transformation of a fertilized egg into a fully developed organism is a complex process, the molecular basis of which is just beginning to be revealed. Recent advances in recombinant DNA methodology, coupled with powerful genetic and embryological techniques, have led to the identification of a small number of regulatory genes which play pivotal roles in orchestrating the developmental program in vertebrate embryos. This proposal focuses on one of these genes called 1mx-1a. Molecular analysis of 1mx-1a indicates that it is a LIM- homeodomain transcription factor, and functions to regulate the synthesis of other , as yet undetermined, gene products. 1mx-1a is produced in discrete subsets of cells of the developing limb and the central nervous system during early stages of their formation, before any sign of overt differentiation has occurred. Based on its expression pattern in chick and mouse embryos, 1mx-1a is likely to play a primary regulatory role in the specification and coordination of cell fates in the limb and brain. In order to define the function of 1mx-1a in the development of limbs and of the mid-hindbrain region of the central nervous system, mice lacking this gene will be generated using embryonic stem cell technologies. The development of these mice will be studied using a variety of molecular and histological methods to define defects which arise from deletion of 1mx-1a. In addition, 1mx-1a will be expressed outside of its normal boundaries in chick embryos using recombinant avian viral vectors. The effect of this manipulation on the development of the chick mid-hindbrain region will be determined using molecular and anatomical markers of cell fate. Finally, the expression of 1mx-1a will be examined in mice with defects in limb and mid-hindbrain development to determine whether 1mx-1a might be involved in the generation of these lethal phenotypes. It is expected that these studies will greatly enrich our current understanding of vertebrate developmental mechanisms. Furthermore, the reagents generated as a result of this work will facilitate future endeavors aimed at defining specific molecular genetic processes which underlie the acquisition of shape and form during animal embryogenesis. Finally, these studies bear directly on human embryonic development since developmental mechanisms, including specific gene products, are well conserved among all vertebrates. Therefore, it is not unreasonable to assume that this work may lead to novel modalities aimed at the diagnosis and prevention of developmental anomalies of the limbs and brain.