VERTEBRATE MIDBRAIN AND LIMB DEVELOPMENT

受精卵向发育完全的 生物体是一个复杂的过程，其分子基础是 才刚刚开始显露。 重组生物技术的最新进展 DNA方法，加上强大的基因和 胚胎学技术，导致了一个小的识别 许多调控基因在 协调脊椎动物胚胎的发育程序。 这项计划的重点是这些基因之一，称为1 mx-1a。 1 mx-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。1 mx-1a是 在发育肢体的离散细胞亚群中产生， 中枢神经系统在其形成的早期， 在任何明显分化的迹象出现之前。 基于其 在鸡和小鼠胚胎中的表达模式，1 mx-1a可能是 在规范中发挥主要监管作用， 肢体和大脑中细胞命运的协调。 为了定义 1 mx-1a在肢体发育和 中枢神经系统的中后脑区域，小鼠缺乏 这个基因将由胚胎干细胞 技术. 将研究这些小鼠的发育情况 使用各种分子和组织学方法来定义 由1 MX-1A缺失引起的缺陷。 此外，1 mx-1a 会在小鸡体内的正常范围外表达 使用重组禽病毒载体的胚胎。 这样做的效果 鸡中后脑发育的手法 将使用分子和解剖学标记来确定区域 细胞的命运 最后，将检查1 mx-1a的表达 在四肢和中后脑发育缺陷的小鼠中， 确定1 mx-1a是否可能参与生成 这些致命的表型。 预计这些研究将 极大地丰富了我们对脊椎动物 发展机制。 此外，生成的试剂 作为这项工作的结果，将促进未来的努力， 定义了特定的分子遗传过程， 在动物胚胎发育过程中获得形状和形态。 最后，这些研究直接关系到人类胚胎 发展机制，包括具体的 基因产物，在所有脊椎动物中是很保守的。 因此，假设这项工作可能 导致新的模式，旨在诊断和预防 四肢和大脑的发育异常

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.