VISUAL SYSTEM DEVELOPMENT AND SYNAPTOGENESIS

我们建议研究控制突触形成的因素 以及第一神经桩，椎板， 果蝇的视叶 特别是，我们的长期目标是 了解多接触突触的发育组装 （二进制，三进制等），果蝇感受器四分体突触 模特 这就涉及到定性的方面（个人如何 四分体组装）和数量（它们的数量和位置）。 的 薄片的模块，称为药筒，包括小的、固定的数量， 我们非常熟悉的神经元。 我们将 我们继续分析这些细胞：1）突触的EM计数 2）图像分析测量， 突触连接大小和细胞尺寸; 3）基于串行EM的计算机 未成熟板层细胞的3-D重建; 4）冷冻干燥， 免疫电镜方法。我们将研究：A。 突触可塑性从快速 突触变化发生在光适应，通过研究 新的突触部位相对于旧的位置，以检查 现有位点对新突触位点形成的影响 附近 我们还将研究突触的活动依赖性， 在传递到突触后细胞受损的突变体中形成。 我们将把突触的形成与树突生长的模式联系起来， 未成熟的板层细胞在3-D重建，从间距和 未成熟和存活突触的组成。 我们将寻求 外源靶点和它们与光感受器轴突的突触接触 遗传性异位眼的例子 B。 蛋白质的表达， 定位于突触或间隙连接，或在突触发生期间起作用， 光感受器和板层细胞。 传递系统蛋白质，间隙 连接和细胞粘附将用抗体探针来检测。 C. 果蝇突变体，引入遗传定义的扰动， 板层细胞 我们将研究突变体的结构， 钙粘蛋白和fas II基因，以及缺乏正常 光感受器之间的染料耦合 在间隙连接突变体中。 D. 最后，我们将利用组织培养 我们开发的系统，检查选择性肌束震颤， 光感受器轴突及其与板层细胞的相互作用 目标的 这里提出的研究，因为他们的目的是产生一个基本的 适用于多接触突触的突触发生模型，例如 在视觉系统中广泛存在的二元组和三元组， 对疾病状态的扰动的一般知识， 视觉突触在其生长和发育期间是易受影响的。

We propose to study the factors controlling the formation of synapses and gap junctions by photoreceptors in the first neuropile, the lamina, of the fly's optic lobe. In particular, our long-term objective is to understand the developmental assembly of multiple-contact synapses (dyads, triads, etc.), for which the fly receptor tetrad synapses are a model. This entails aspects that are both qualitative (how individual tetrads assemble) and quantitative (their number and location). The modules of the lamina, called cartridges, comprise small, fixed numbers of identified neurons with which we are intimately familiar. We will continue our analysis of these cells with: 1) EM counts of synapse numbers by the disector method; 2) image analysis measurements of synaptic junction sizes and cell dimensions; 3) serial-EM based computer 3-D reconstructions of immature lamina cells; 4) cryo-ultrathin and immuno-EM methods. We will examine: A. Synaptic plasticity from rapid synaptic changes occurring during light adaptation, by studying the location of new synaptic sites relative to old ones, to examine the influence of an existing site on the formation of a new synaptic site nearby. We will also examine the activity-dependence of synapse formation in mutants with impaired transmission to postsynaptic cells. We will relate synapse formation to the pattern of dendrite growth in immature lamina cells reconstructed in 3-D, from the spacing and composition of immature and surviving synapses. We will seek the foreign targets and their synaptic contacts from the photoreceptor axons of genetically induced ectopic eyes. B. Expression of proteins that localize at synapses or gap junctions, or act during synaptogenesis in photoreceptors and lamina cells. Proteins for transmitter systems, gap junctions and cell adhesion will be expored with antibody probes. C. Drosophila mutants that introduce genetically defined perturbations to lamina cells. We will examine the structure of mutants that mis-express the cadherin and fas II genes, and ERG mutants that lack normal transmission to the lamina, and the dye-coupling between photoreceptors in a gap junction mutant. D. Finally, we will exploit a tissue-culture system we have developed, to examine selective fasciculation amongst photoreceptor axons and their interactions with their lamina cell targets. 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 a general knowledge of the perturbations in disease states to which visual synapses are susceptible during their growth and-development.