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 在两个方面：1)我们将使用定量的单截面EM来估计 突触频率，测量突触接触部位和细胞表面 区域。2)我们还将使用序列EM追踪突触连接 并进行细胞的计算机三维重建 形态特征。基于我们之前对正常突触发生的分析， 我们特别想了解对发育的控制 多接触突触(二联体、三联体等)的组装 苍蝇受体四分体突触就是一个模型。跨物种移植 旨在允许嵌合突触发生的实验将测试 同源神经元间突触发生信号的保守性 不同的物种。三重突变体rol/sol/mnb将导致损失 四分体的突触后贡献者的不同组合， 在突触发生之前通过自发的细胞退化，并允许 存活的细胞有机会取代那些失去的细胞，从而 展示他们的突触基因偏好。我们会像辐射苍蝇一样 用预蛹杀死包裹叶层的上皮神经胶质细胞 盒，并探索突触的后果和速度， 预期从完整的墨盒的中间神经元萌发到 视网膜严重去传入的相邻墨盒 光消融。我们将扩大我们最初的采购方法 光感受器与光感受器共培养的体外突触发生 视叶细胞。我们将继续进行主要的计算机三维重建 一个完整的椎板药筒EM系列，以量化空间 分布于神经元上的突触群体的特征 表面，尤指构成相互连接的表面 在神经元之间。我们将检查椎板的动态变化 卡特里奇：1)在昼夜节律期间的突触群体中，以及 在冷应激之后，这两者都会导致短期变化，以及2) 中间神经元，显示每天的大小变化；以及研究这些 从功能上讲来自长期的ERG记录。最后，我们将聘用 增强子陷阱方法：1)研究已鉴定的视神经组织中的基因表达 叶间神经元，尤指在已知条件下发生的 促进突触发生，以及2)产生特定的分子 这些细胞的标记。在这里提出的研究，因为他们的目标是 提出适用于多接触的突触发生的基本模型 突触，如视觉系统中广泛存在的二联体和三联体， 应该有助于对微扰的一般理解 视觉突触在大脑发育过程中易受影响的疾病状态 成长和发展。

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 in two ways: 1) We will use quantitative single-section EM to estimate synaptic frequencies, measure synaptic contact sites and cell surface areas. 2) We will also use 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 chimeric synaptogenesis will test the conservation of synaptogenetic signals between homologous neurons in different species. The triple mutant rol/sol/mnb will procure the loss of differing combinations of postsynaptic contributors to the tetrads, through spontaneous cell degeneration prior to synaptogenesis, and allow surviving cells the opportunity to replace those lost, and thereby exhibit their synaptogenetic preferences. We will irradiate flies as prepupae to kill the epithelial glial cells that envelop the lamina cartridges, and explore the synaptic consequences, and rapidity, of anticipated sprouting from the interneurons of intact cartridges to adjacent cartridges which have been acutely deafferented by retinal photo-ablation. We will extend our initial approaches to procure synaptogenesis in vitro through the co-culture of photoreceptors and optic lobe cells. We will continue a major computer 3-D reconstructions of a complete lamina cartridge EM series to quantify the spatial characteristics of synaptic populations distributed over neuronal surfaces, especially those which constitute reciprocal connections between neurons. We will examine dynamic changes in the lamina cartridge: 1) amongst synaptic populations during a circadian rhythm, and after cold stress, both of which cause short-term changes, and 2) amongst interneurons, which show daily size changes; as well as investigate these functionally from long-term ERG recordings. Lastly, we will employ enhancer trap methods: 1) to study gene expression in identified optic lobe interneurons, especially that occurring under conditions known to promote synaptogenesis, as well as 2) to generate specific molecular markers to these cells. 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.