VISUAL SYSTEM DEVELOPMENT AND SYNAPTOGENESIS

利用我们对果蝇视叶的专业解剖学知识，我们将研究果蝇光感受器终末及其第一神经丛--板层中的靶内脏基因的表达和功能。我们的长期目标是了解多接触突触(二联体、三联体等)的功能组织、它们的形成以及神经活动在这一过程中的作用。目前的目标是研究光感受器终末及其中间神经元中的突触组织，以及编码突触蛋白的基因的功能作用，特别是通过对突触蛋白板层的表型分析和基因表达模式的定义。使用先进的共聚焦、定量-EM、序列-EM、免疫-EM和E-D重建方法，以及熟练的人员来实施这些方法，我们将准确地分析对照和突触突变果蝇的表型。我们将检查：a.光感受器末端突触蛋白基因的功能作用，来自米尔顿、NOC、两体素、CSPA和D-Huntingtin等突变体的EM表型，以及来自合作实验室正在对具有ERG缺陷的全眼马赛克苍蝇进行筛选的新突变体的功能，这些缺陷可归因于叶片中的传输障碍。基因产物在光感受器末端的体内和体外表达，使用指向光感受器末端的突触前部位及其突触后靶细胞的探针，用去卷积的共聚焦图像显示并通过免疫-EM进行定位。C.视觉突触的结构组织和基因表达的动态方面，以及神经活动在传入光感受器四分体及其反馈伙伴的发育组装中的作用，以及成虫在光诱发活动后的短期突触发生中的作用。D.利用EM标志物在髓质细胞中的靶向表达，研究由长光感受器轴突和板层细胞终末支配的第二神经桩或延髓远端神经束的微循环，为解释这一复杂神经桩的突变结构提供基础。这里提出的研究，因为他们的目标是建立一个适用于多接触突触的基本突触发生模型，例如在视觉系统中广泛存在的二联体和三联体，这将有助于了解视觉突触在生长、发育和功能过程中容易受到的疾病状态的扰动，以及这些突触的遗传基础。

Exploiting our expert anatomical knowledge of the fly's optic lobe, we will examine the expression and function of genes in Drosophila photoreceptor terminals and their target internourons in the first neuropile, the lamina. Our long-term objective, for which fly photorecepto tetrad synapses Are a genetically manipulable model, is to understand the functional organization of multiple-contact synapses (dyads, triads, etc.), their formation and the role of neural activity in this process. Current objectives are to study synaptic organization in photoreceptor terminals and their interneurons, and the functional role of genes that code for synaptic proteins, especially as defined by phenotypic analyses of, and patterns of gene expression in, the lamina. Using advanced confocal, quantitative-EM, serial-em, immuno-EM and E-D reconstruction methods, and skilled personnel to implement these, we will precisely assay the phenotypes of control and synaptic mutant flies. We will examine: A. The functional role of genes for synaptic proteins in photoreceptor terminals, from EM phenotypes of mutants such as milton, noC, amphiphysin, cspa and D-huntingtin, and of new mutants from screens being conducted in collaborating laboratories for whole-eye mosaic flies with ERG defects that are attributable to impaired transmission in the lamina. The in vivo and in vitro expression of gene products in photoreceptor terminals, using probes directed to the pre-synaptic site at the photoreceptor terminal and to its lamina post- synaptic target cells, visualized with deconvolved confocal images and localized by immuno-EM. C. Dynamic aspects of structural organization and gene expression at visual synapses, and the role of neural activity in both the development assembly of afferent photoreceptor tetrads and their feedback partners, and short-term synaptogenesis in adult flies after light-evoked activity. D. The micro-circuits of distal straita in the second neuropile, or medulla, innervated by long photoreceptor axon and lamina cell terminals, using targeted expression of EM markers in medulla cells, to provide a basis upon which to interpret mutant structure in this complex neuropile. The studies proposed here, because they aim to produce a basic model of synaptogenesis applicable to multiple-contact synapses, such as the dyads and triads found widely in visual systems, will contribute to knowledge of the perturbations in disease states to which visual synapses are susceptible during their growth, development and function, and to the genetic bases of these.