VISUAL SYSTEM DEVELOPMENT AND SYNAPTOGENESIS

本项目的总体目标是研究控制经济增长的因素 光感受器突触的数量和质量组成 在苍蝇视叶的第一神经丛或板层 果蝇和麝香。这个神经堆的模块，被称为管状物， 包括少量固定数量的已识别神经元，我们将对其进行采样 使用定量的单节EM来估计突触频率， 测量突触接触部位和细胞表面积；以及连续的EM到 找出元素之间的突触联系，并进行计算机 细胞形态的三维重建。基于我们之前的分析 对于正常的突触发生，我们特别想了解 多接触突触的发育组装(二联体、三联体、 等)，苍蝇受体四分体突触就是一个模型。 跨物种移植实验旨在允许杂交 突触发生将测试突触发生信号的保守性 在不同物种的同源神经元之间。变种人Vam会 使突触后四分体的一种成分通过其 自发退化，使其他细胞有机会替代 它，所以揭示了他们的突触发生偏好。我们将探索一种 第二个突变体，non c，与我们之前的 野性类型的描述，作为视觉连接的第一个分析 变种人。将在突变的Gigas中检查定量的突触发生， 观察细胞增大对突触频率的因果影响。 将使用完整的EM系列墨盒来评估 共享传入突触和反馈突触的细胞之间的突触相互作用， 面对大小引起的突触频率的变化。动态 成年突触的某些方面将在以下突触丢失期间进行检查 光消融感受器终末的退化，以及在正常情况下 椎板内突触的翻转。叶层细胞终末的连接 在第二个视神经桩的探索中也将完成 这些细胞的突触清单，从而加深了我们对 在视觉突变体中对遗传损伤敏感的电路。这些研究 在这里提出，因为他们的目标是产生一个基本的突触发生模型 适用于多触点突触，如二联体和三联体 广泛存在于视觉系统中，应该有助于一般 对疾病状态中的扰动的理解 突触在生长和发育过程中很容易受到影响。

The general aims of this project are to study the factors controlling the numerical and qualitative composition of photoreceptor synapses that form in the first neuropile, or lamina, of the optic lobe of the flies Drosophila and Musca. The modules of this neuropile, called cartridges, comprise small, fixed numbers of identified neurons, which we will sample using quantitative single-section EM to estimate synaptic frequencies, measure synaptic contact sites and cell surface areas; and serial EM to trace out synaptic connections between elements, and undertake computer 3-D reconstructions of cell morphologies. Based on our previous analysis of normal synaptogenesis, we especially want to understand the control of the developmental assembly of multiple-contact synapses (dyads, triads, etc.), for which the fly receptor tetrad synapses are a model. Cross-species transplant experiments designed to allow hybrid synaptogenesis will test the conservation of synaptogenetic signals between homologous neurons in different species. The mutant Vam will procure the loss of one element of the postsynaptic tetrad through its spontaneous degeneration, allowing other cells the opportunity to replace it, so revealing their synaptogenetic preferences. We will explore a second mutant, nonC, for abnormal connections with respect to our previous wild-type descriptions, as the first analysis of visual connectivity mutants. Quantitative synaptogenesis will be examined in the mutant gigas, to examine the causal influence of cell enlargement on synaptic frequency. Complete EM series of the cartridge will be used to assess the ratio of synaptic reciprocity between cells sharing afferent and feedback synapses, in the face of size-induced variations in synaptic frequencies. Dynamic aspects of adult synapses will be examined during synaptic loss following degeneration of photo-ablated receptor terminals, and during normal synaptic turnover in the lamina. The connections of lamina cell terminals in the second optic neuropile will also be explored to complete the synaptic inventory of these cells, thereby furthering our understanding of the circuits susceptible to genetic lesions in visual mutants. 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, should contribute to a general understanding of the perturbations in disease states to which visual synapses are susceptible during their growth and development.