A RE-EXPLORATION OF THE ORIGIN OF NEURONS

这项研究的目的是重新探索神经元（中枢神经系统的细胞）的发育起源。 普遍的观点是，所有的神经元都来自外胚层，外胚层是胚胎发育过程中的三个主要胚层之一。 基于大量的命运图谱和细胞谱系研究，这一结论对大多数神经元都是正确的，但它对所有神经元都是正确的吗？ 我最近在果蝇中线中胚层细胞（MMCs）的工作提出了一个有趣的假设，即具有神经元功能的细胞不一定总是外胚层来源的。 这一假设将在使用MMCs的建议中进行严格检查，MMCs是一组20个果蝇细胞，它们明确地起源于中胚层，但表现出许多神经元特性。 它们有一个突出的细胞体，两个主要的过程突出一个特定的神经到一个特定的骨骼肌，表达几个神经特异性标志物，有电压依赖性通道，接受突触样输入，并影响几个靶组织。 本研究的两个目的是解决神经元状态的剩余标准，即MMCs是否表达和释放神经递质样分子。成功的结果将提供第一个明确的例子，神经元来自非外胚层谱系。

The goal of this research is to re-explore the developmental origin of neurons, the cells of the central nervous system. The universally held view is that all neurons arise from the ectoderm, one of the three primary germ layers during embryogenesis. This conclusion, based on numerous fate mapping and cell lineage studies, is undoubtably true for the majority of neurons, but is it true for all neurons? My recent work on the Midline Mesodermal Cells (MMCs) in fruit fly Drosophila melanogaster raises the interesting hypothesis that cells with a neuronal function need not always be ectodermally derived. This hypothesis will be critically examined in the proposed using the MMCs, a set of 20 cells in flies which are unequivocally mesodermal in origin yet exhibit a number of neuronal properties. They have a prominent cell body, two primary processes projecting out a specific nerve to a specific skeletal muscle, express several neural-specific markers, have voltage dependent channels, receive synaptic-like inputs, and affect several target tissues. The two aims in this study address the remaining criteria for neuronal status, namely whether the MMCs express and release neurotransmitter-like molecules. Successful results will provide the first clear cut example of neurons arising from a non-ectodermal lineage.