MYOGENESIS SUBSEQUENT TO DENERVATION

体内肌生成与发育同时发生， 神经系统的成熟。 最近描述的技术允许 不干扰胎鼠的实验操作 活力和成熟。 这些技术将应用于激光 切除幼胎的脊髓并切断坐骨神经 的年龄较大的胎儿，允许去神经支配的影响进行评估 (at不同的发展阶段）的发展和成熟 哺乳动物肌纤维 将使用电子显微镜进行评价 和形态测量学。 我们还将评估胎儿去神经支配的效果 对编码各种肌球蛋白的肌肉特异性基因的表达 小鼠后肢肌肉肌动蛋白亚型的原位杂交研究 用免疫组织化学技术 这将允许区分存在于原发性与非原发性肿瘤中的同种型， 次级肌管 基因表达的时间进程编码的 胎儿和成人形式的肌酸激酶和编码 乙酰胆碱受体的各种亚单位（胎儿和成人 受体）将在受神经支配的后肢肌肉中用原位 杂交方法 然后，我们将评估去神经支配对 这些基因和编码肌生成因子的基因的表达 MyoD1和myogenin。 拟议的研究将使我们能够评估 环境对肌肉发育的先天遗传程序的影响： 1)它将允许评估细胞相互作用以及神经元如何 可能在承诺、分化或改变行为中发挥作用 的肌肉细胞。 2)我将允许确定 神经调节是维持肌肉表型所必需的， 发展的过程。 从拟议的 研究将增加我们的“。理解细胞和分子 参与肌肉发育的过程还有将是无价 在设计和实施技术，以修复肌肉， 由于遗传或环境原因而受损或丧失功能”。

In vivo myogenesis occurs simultaneously with the development and maturation of the nervous system. Recently described techniques permit experimental manipulation of mouse fetuses without interfering with fetal viability and maturation. These techniques will be applied to laser ablate the spinal cords of young fetuses and to cut the sciatic nerves of older fetuses, permitting the evaluation of the effects of denervation (at various developmental periods) on the development and maturation of mammalian myofibers. Evaluation will be made with electron microscopy and morphometry. We also will evaluate the effect of fetal denervation on the expression of muscle specific genes encoding the various myosin and actin isoforms in mouse hindlimb muscles with in situ hybridization and with immunohistochemistry, using an immunohistochemical technique which will permit differentiation of isoforms present in primary versus secondary myotubes. The time course of expression of genes encoding the fetal and adult forms of creatine kinase and the genes coding for the various subunits of the acetylcholine receptor (both the fetal and adult receptors) in innervated hindlimb muscles will be determined with in situ hybridization. We then will evaluate the effects of denervation on the expression of these genes and the genes encoding the myogenic factors MyoD1 and myogenin. The proposed studies will allow us to assess the effect of environment on the innate genetic program of developing muscle: 1) It will permit assessment of cell interactions and of how the neuron may play a role in commitment, differentiation, or change the behavior of muscle cells. 2) I will permit determination of the extent to which nerve regulation is required for the maintenance of muscle phenotypes in the course of development. Information generated from the proposed studies will increase our "...understanding of the cellular and molecular processes involved in muscle development ..." and "... will be invaluable in the design and implementation of techniques to repair muscles that are damaged or nonfunctional due to genetic or environmental causes".