DEVELOPMENT OF MOTONEURONAL CONNECTIVITY

细胞间的诱导相互作用调节脊椎动物的许多方面 发育，包括神经系统的形成和模式。 感应信号的失败会导致各种各样的出生和 发育缺陷。尽管显而易见的重要性和许多类型的 脊椎动物发育所需的诱导相互作用，细胞 大多数情况下，调节这种相互作用的分子机制是 部分，人们知之甚少。 这项建议寻求对发展的更详细的理解 诱导第一肌细胞形成的信号过程，称为 肌肉先锋。对斑马鱼胚胎的分析表明，肌肉 先驱者崛起并承担起他们特殊的细胞命运，与 其他肌肉细胞，作为来自于 弦乐。 要了解脊索和脊索之间的这些相互作用的时间和地点 肌肉出现，脊索前体细胞，将a)激光移除 在诱导过程中的不同时间进行消融，b)随后 活胚胎中的荧光染料，以及c)在培养中生长的 肌肉前体的存在。 为了了解诱导过程的遗传调控， NTL和SPT两个突变之间的相互作用，扰乱了 肌肉先锋，将被刻画出来。肌肉先锋的诱导 将在移植野生型脊索前体细胞后进行检测 转化为缺少脊索的NTL突变体，b)来自SPT的脊索前体 缺乏肌肉先锋的突变体，变成NTL突变体，以及c)野生型 前体转化为NTL/SPT双突变体。通过确定以下条件 拯救脊索，肌肉先驱，以及两者，精确的细胞 对已鉴定基因的诱导和功能的要求 通过这些突变，我们就可以了解到。 以开始确定潜在的分子遗传机制 诱导过程，在肌肉先锋中表达的基因 脊索诱导的特征是分析它们的启动子和 它们在转基因鱼中的功能，以及影响 肌肉先锋和肌肉图案的形成将恢复和 特色化的。

Inductive interactions between cells regulate many aspects of vertebrate development, including formation and patterning of the nervous system. Failures of inductive signaling give rise to a wide variety of birth and developmental defects. Despite the obvious importance and many types of inductive interactions required for vertebrate development, the cellular and molecular mechanisms that regulate such interactions are, for the most part, poorly understood. This proposal seeks a more detailed understanding of a developmental signaling process that induces formation of the first muscle cells, termed muscle pioneers. Analysis of zebrafish embryos has shown that muscle pioneers arise and take on their specialized cell-fates, distinct from other muscle cells, as a result of inductive influences from the notochord. To learn when and where these interactions between the notochord and muscle occur, notochord precursors cells, will be a) removed by laser ablation at various times during the inductive process, b) followed with fluorescent dyes in live developing embryos, and c) grown in culture in the presence of muscle precursors. To understand the genetic regulation of the induction process, interactions between two mutations, ntl and spt, that perturb formation of muscle pioneers, will be characterized. The induction of muscle pioneers will be assayed after transplanting a) wild-type notochord precursor cells into ntl mutants, which lack notochords, b) notochord precursors from spt mutants, which lack muscle pioneers, into ntl mutants, and c) wild-type precursors into ntl/spt double mutants. By determining the conditions for rescue of notochord, muscle pioneers, and both, the precise cellular requirements for the induction and the functions of the genes identified by these mutations will be learned. To begin identifying the molecular genetic mechanisms underlying the inductive process, genes expressed in muscle pioneers in response to notochord induction will be characterized by analyzing their promoters and their functions in transgenic fish, and new mutations that affect the formation of muscle pioneers and muscle patterning will be recovered and characterized.