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端及其在第一神经桩，即椎板中的目标内核的基因表达和功能。我们的长期目标是了解多接触突触（二联、三联等）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，因为苍蝇的光感受器四联突触是一种可遗传操纵的模型。目前的目标是研究光感受器末端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，特别是通过表型分析和基因表达模式来定义，在板中。利用先进的共聚焦、定量em、串行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，我们将精确地分析对照和突触突变果蝇的表型。我们将研究：A.光受体末端突触蛋白基因的功能作用，来自突变体（如milton， noC, amphiphysin， cspa和D-huntingtin）的EM表型，以及来自合作实验室对具有ERG缺陷的全眼花叶果蝇的新突变体的筛选，这些缺陷可归因于板层传输受损。基因产物在光感受器末端的体内和体外表达，使用探针指向光感受器末端的突触前位点及其层状突触后靶细胞，用反卷积共聚焦图像可视化并通过免疫电镜定位。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，以及光诱发活动后成虫的短期突触发生。D.第二神经堆或髓质的远端条纹的微电路，由长光感受器轴突和层状细胞终末支配，利用髓质细胞中EM标记的靶向表达，为解释这种复杂神经堆的突变结构提供基础。这里提出的研究，因为他们的目的是建立一个适用于多接触突触的基本模型，如视觉系统中广泛发现的二联体和三联联体，将有助于了解视觉突触在生长、发育和功能过程中易受疾病状态扰动的影响，以及这些扰动的遗传基础。

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.