MOLECULAR BASES OF NEURONAL CONNECTIVITY

拟议的研究将调查具体的作用 蛋白质在发育、再生和调节 视觉系统中的连接。 一个主要的焦点是 突触前膜磷蛋白（GAP-43或- 48，B-50，pp 46，F1），其以高水平表达并被传送 轴突生长过程中的神经末梢 在大多数神经元中，它的合成下降 随着成熟而急剧上升，但在轴突生长期间再次上升。 再生 我们已经研制出了针对这种病毒的单特异性抗体 蛋白质以及cDNA探针，我们将用它来研究 促进连接的发展和功能调节 在视觉系统中。 我们将研究时间关系 金鱼视神经的再生与 差距/B-50基因的表达，使用北方印迹分析， 用cDNA探针进行原位杂交;特别感兴趣 问题是它的表达是否与 “敏感期”，在此期间，突触组织可以 由活性依赖机制调节。 我们还将 研究哺乳动物视神经的再生， 这可以通过移植的外周神经段发生， 同样依赖于差距/B-50基因的再诱导。 另一项研究将调查正常的时间进程 GAP/B-50在不同视觉加工区的表达， 在人类和啮齿类动物的大脑中都能完成。 这将 帮助确定不同区域何时形成和重组 连接，也将使我们能够确定继续 在整个生命过程中表达基因，因此可能是 能够不断地改变它们的突触关系。 其他研究将检查生物合成和可能的功能 差距/B-50蛋白的表达。 第二个一般研究领域将分离和表征 大分子，分泌的非神经元细胞的 金鱼的视神经，调节轴突的生长。 初步结果表明，神经胶质鞘细胞分泌 一种促进神经突生长的蛋白质和另一种 抑制生长，表明这些之间的平衡 可能决定轴突是否会再生的 这些因素的识别可以提供有价值的见解， 最终影响损伤后神经元的生长， 哺乳动物视觉系统

The proposed research will investigate the role of specific proteins in the development, regeneration, and modulation of connections in the visual system. One major focus on this research is a presynaptic membrane phosphoprotein (GAP-43 or - 48, B-50, pp46, F1) that is expressed at high levels and conveyed to the nerve endings during axonal outgrowth and the organization of synaptic relationships; in most neurons its synthesis declines precipitously with maturation, but rises again during axonal regeneration. We have developed monospecific antibodies to this protein as well as a cDNA probe, which we will use to investigate further the development and functional modulation of connections in the visual system. We will examine the temporal relationship between the regeneration of the optic nerve of goldfish and the expression of the GAP/B-50 gene, using Northern blot analysis and in situ hybridization with the cDNA probe; of particular interest will be the question of whether its expression correlates with the "sensitive period, "during which synaptic organization can be modulated by activity-dependent mechanisms. We will also examine whether the regeneration of the mammalian optic nerve, which can occur through a grafted segment of peripheral nerve, likewise depends upon reinduction of the GAP/B-50 gene. Another line of research will investigate the normal time course of the expression of GAP/B-50 in various visual processing areas, and will be done in both the human and rodent brains. This will help define when different areas are forming and reorganizing connections, and will also allow us to identify areas that continue to express the gene throughout life, and which thus may be capable of modifying their synaptic relationships continuously. Other studies will examine the biosynthesis and possible functions of the GAP/B-50 protein. A second general area of research will isolate and characterize macromolecules, secreted by the non-neuronal cells of the goldfish optic nerve, that regulate the growth of axons. Preliminary results indicate that the glial sheath cells secrete both a neurite-promoting protein and another molecule that is inhibitory to growth, suggesting that the balance between these may determine whether axons will regenerate or not. The identification of these factors may provide insights valuable for ultimately effecting growth of neurons after damage in the mammalian visual system.