Lineage-associated wiring properties of Drosphila brain neurons

 描述（由申请人提供）：大脑功能基于大量神经元的精确连接。连接性反过来又在很大程度上取决于神经元的遗传决定的布线特性，包括它们的神经突投射、分支以及与特定伙伴的突触接触的位置。为了理解和操纵大脑回路，我们需要详细了解发育中的神经元中表达的基因如何控制该细胞的布线特性。在遗传学研究中，果蝇有许多优势，因为几乎每一个基因都可以在一种细胞类型中被敲除或激活 选择性的方式。在研究神经元回路的背景下，更重要的是，果蝇的大脑由可管理数量的定型神经元谱系组成，这些神经元群来自胚胎中出生的单个干细胞（成神经细胞）。在其增殖过程中，每一个神经母细胞表达一组特征性的基因（转录因子），这些基因被认为是在特定的时间间隔内指定从该特定神经母细胞产生的神经元的布线特性。这些神经元形成了所谓的亚谱系。为了了解大脑回路的遗传控制，我们和其他人采取了记录谱系和亚谱系的结构特性的方法，并将它们与成神经细胞中基因表达的动态模式相关联。 在上一个资助期间，我们已经生成了构成成人和幼虫大脑的所有谱系的详细地图和3D模型。我们在此提出三个目标，以继续和扩大这项工作。首先，我们将重建幼虫脑谱系及其亚谱系的一个子集的连接， 良好的电路特性。这种重建将以前所未有的分辨率进行，使用一系列数千个连续的电子显微镜切片，结合一个专门开发的软件包，使我们能够将所有突触分配给特定的神经元及其谱系。其次，我们将使用一种技术，系统地标记成神经细胞中表达的所有转录因子，然后跟踪这些基因从成神经细胞到谱系的表达，将幼虫脑中映射的结构定义谱系与胚胎的成神经细胞联系起来。第三，我们将筛选和遗传特征的基因，在指导谱系在电路中的适当位置发挥作用。

 DESCRIPTION (provided by applicant): Brain function is based upon the precise connectivity of a large number of neurons. Connectivity in turn depends in large part on the genetically determined wiring properties of neurons, including their neurite projection, branching, and placement of synaptic contacts with specific partners. To understand and manipulate brain circuits one needs a detailed knowledge of how the genes expressed in a developing neuron control the wiring properties of this cell. For genetic studies, Drosophila offers many advantages, in that virtually every gene can be targeted for knock-out or activation in a cell type selective manner. More importantly in the context of studying neuronal circuitry, the Drosophila brain is composed of a manageable number of stereotyped neuronal lineages, groups of neurons descended from individual stem cells (neuroblasts) born in the embryo. During the course of its proliferation, each neuroblast expresses characteristic sets of genes (transcription factors) which are thought to specify the wiring properties of the neurons born from that particular neuroblast during a particular time interval. These neurons form a so called sublineage. To learn about the genetic control of brain circuitry we and others have taken the approach to document the structural properties of lineages and sublineages, and correlate them to the dynamic pattern of gene expression in the neuroblast. During the previous funding period we have generated detailed maps and 3D models of all lineages constituting the adult and larval brain. We here propose three aims that continue and extend this work. First, we will reconstruct the connectivity of a subset of larval brain lineages and their sublineages that form a particular, well characterized circuit. This reconstruction will be done at a so far unparalleled level of resolution, using a series of several thousand contiguous electron microscopic sections in conjunction with a specially developed software package that allows us to assign all synapses to specific neurons and their lineages. Secondly, we will link the structurally defined lineages mapped in the larval brain with the neuroblasts of the embryo, using a technique that systematically labels all transcription factors expressed in neuroblasts and then follows the expression of these genes from neuroblast to lineage. Thirdly, we will screen for and genetically characterize genes that play a role in directing lineages to their proper place in a circuit.