VISUAL SYSTEM DEVELOPMENT AND SYNAPTOGENESIS

我们建议研究控制突触形成的因素 以及第一神经纤维层中光感受器的缝隙连接， 苍蝇的视叶。特别是，我们的长期目标是 了解多接触突触的发育组装 (二联体、三联体等)，其苍蝇受体四分体突触是 一个模特。这需要两个方面都是定性的(如何个别 四分体聚集)和数量(它们的数量和位置)。这个 薄层的模块称为墨盒，由小而固定的数字组成 我们非常熟悉的识别出的神经元。我们会 继续我们对这些细胞的分析：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)基于串口EM的计算机 未成熟椎板细胞的三维重建；4)冷冻超薄和 免疫-EM法。我们将检查：a.快速突触的可塑性 通过研究在光适应过程中发生的突触变化 新的突触位置相对于旧的突触位置，以检查 现有部位对新突触部位形成的影响 就在附近。我们还将研究突触的活性依赖性。 突触后细胞传递受损的突变体的形成。 我们将把突触的形成与树突的生长模式联系起来。 在3D中重建的未成熟椎板细胞，从间隔和 未成熟和存活的突触的组成。我们将寻求 来自光感受器轴突的外来靶点及其突触接触 基因诱导的异位眼。B.表达下列蛋白： 定位于突触或缝隙连接，或在突触发生期间起作用 光感受器和板层细胞。传递系统的蛋白质，GAP 用抗体探针检测连接和细胞黏附情况。C。 果蝇突变体将基因定义的扰动引入到 板层细胞。我们将检查错误表达的突变体的结构。 钙粘附素和Fas II基因，以及缺乏正常的ERG突变 传递到叶片，光感受器之间的染料耦合 在缝隙连接突变体中。最后，我们将开发一种组织培养 我们开发的系统，用于检查 光感受器轴突及其与板层细胞的相互作用 目标。在这里提出的研究，因为他们的目标是产生一个基本的 适用于多接触突触的突触发生模型，如 由于视觉系统中广泛存在的二联体和三联体，将有助于 对于疾病状态中的扰动的一般知识 视觉突触在生长发育过程中很容易受到影响。

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.