Development and Function of the Mammalian Olfactory System

过去一年的研究重点是定义 其发生发展的分子机制 哺乳动物的嗅觉系统。特别强调的是 分子的鉴定，指导分子的建立 观察到的突触连接的精确模式 嗅觉的外周感觉神经元及其靶神经元 灯泡。这些研究导致了新成员的识别 在嗅觉中高表达的信号素基因家族 和犁鼻系统。几种不同基因的全长cDNA克隆 对这些基因进行了分离和测序。原位杂交 实验表明，该基因家族的成员都有表达。 在发育的早期阶段，在 初级感觉神经元和球部二尖瓣细胞出现。这个 编码神经毛细蛋白1和2的基因，这两个已识别的信号素 受体，也被发现在嗅觉和 犁鼻系统处于早期发育阶段。特别值得关注的是， 我们发现，特定的信号素及其受体是 在副嗅觉系统和主要嗅觉系统中的差异表达 或在嗅觉上皮的不同区域。功能界别 这些分子的不同分布的意义在于 正在接受调查。研究的第二个焦点是分子 气味受体的特性。为了检查 包括配体在内的气味受体的功能特性 特异性、G蛋白偶联和选择性，以及 配体依赖的修饰，我们目前正在开发一种 异源细胞表达系统。哺乳动物载体包含 几种气味受体的完整编码区是 建造的。稳定和瞬时转染的细胞系产生 目前正在评估高水平的气味受体mrna。 用于生产功能性气味感受器。

Research during the past year focused on defining the molecular mechanisms underlying the development of the mammalian olfactory system. Particular emphasis was placed on the identification of molecules which direct the establishment of the precise patterns of synaptic connectivity observed between peripheral sensory neurons and their target neurons in the olfactory bulb. These studies led to the identification of novel members of the semaphorin gene family that are highly expressed in the olfactory and vomeronasal systems. Full length cDNA clones for several of these genes were isolated and sequenced. In situ hybridization experiments indicate that members of this gene family are expressed early in development during the time when synaptogenesis between primary sensory neurons and bulbar mitral cells is occurring. The genes encoding neuropilin 1 and 2, the two identified semaphorin receptors, were also found to be expressed in the olfactory and vomeronasal systems early in development. Of particular interest, we found that particular semaphorins and their receptors were differentially expressed in the accessory and main olfactory systems or in different zones of the olfactory epithelium. The functional significance of the differential distribution of these molecules is being investigated. A second focus of research was the molecular characterization of odorant receptors. In order to examine the functional properties of odorant receptors including ligand specificity, G- protein coupling and selectivity, and ligand-dependent modifications, we are currently developing a heterologous cell expression system. Mammalian vectors containing the complete coding regions of several odorant receptors were constructed. Stable and transiently transfected cell lines producing high levels of odorant receptor mRNA are currently being evaluated for the production of functional odorant receptors.