Collaborative Research: Role of Glia during Postembryonic Formation of the CNS

合作研究：Mesce和Fahrbach昆虫变态伴随着中枢神经系统的广泛重组。这些变化受类固醇激素的调节，在变态过程中，昆虫神经元和神经胶质细胞表达核类固醇激素受体。蛾类和蝴蝶神经系统变态的一个显著特征是由单个节段性神经节形成复合神经节。六纹夜蛾是一种在实验室中容易饲养的大物种，在毛虫化蛹后不久就形成了复合神经节。这个合作项目将测试一个复合神经节形成的模型，在该模型中，两类胶质细胞是主要的类固醇靶点。在这个模型中，神经节间结缔组织中的巨型神经胶质细胞通过改变细胞结构来移动神经元簇，而包裹中枢神经系统的神经周神经胶质细胞改变了它们的粘附性，允许神经元自由移动。将在明尼苏达大学梅斯博士的实验室进行的实验将描述巨型胶质细胞在复合神经节形成过程中的运动，并将研究巨型胶质细胞的损伤如何影响神经节的迁移和融合。这些实验之所以便利，是因为最近发现一种形式的Fasciclin II，一种在昆虫细胞表面表达的蛋白质，可以用作巨大胶质细胞的标记。将在伊利诺伊大学香槟分校的Fahrbach博士的实验室进行的实验将确定变态过程中神经膜神经胶质细胞增殖的时间，并研究切除这一细胞群对神经节细胞迁移和融合的影响。此外，针对昆虫类固醇激素受体(蜕皮激素受体，ECR)特定亚型的抗体将被用来确定神经胶质细胞表达哪种形式的受体。这被认为是识别类固醇调节基因的第一步，这些基因参与调节胶质细胞骨架和胶质细胞黏附分子。以前对昆虫神经系统变态的研究主要集中在神经元上。该项目将为昆虫胚胎后发育过程中胶质细胞构筑和胶质细胞粘附性的发育调控提供新的信息。这一结果很可能推广到所有节肢动物，而且因为细胞“粘性”和细胞形状的调节是所有多细胞生物体的基本属性，其他动物也是如此。

Collaborative Research: Mesce and Fahrbach Insect metamorphosis is accompanied by extensive reorganization of the central nervous system. These changes are regulated by steroid hormones, and during metamorphosis insect neurons and glia express nuclear steroid hormone receptors. A notable feature of metamorphosis in the nervous system of moths and butterflies is the formation of compound ganglia from individual segmental ganglia. In the moth Manduca sexta, a large species easily reared in the laboratory, compound ganglia form shortly after the caterpillar pupates. This collaborative project will test a model of compound ganglion formation in which two classes of glial cells are the primary steroid targets. In this model, the giant glial cells of the interganglionic connectives move clusters of neurons by changes in their cytoarchitecture while the perineurial glial cells that wrap the central nervous system alter their adhesive properties to permit the neurons to move freely. Experiments to be conducted at the University of Minnesota in Dr. Mesce's laboratory will describe the motility of giant glial cells during the formation of compound ganglia and will study how damage to the giant glial cells affects ganglionic migration and fusion. These experiments are facilitated as a result of the recent discovery that a form of fasciclin II, a protein expressed on the surface of insect cells, can be used as a marker for the giant glial cells. Experiments to be conducted in Dr. Fahrbach's laboratory at the University of Illinois at Urbana-Champaign will determine the timing of perineurial glial cell proliferation during metamorphosis and study the effects of ablation of this cell population on ganglionic migration and fusion. In addition, antibodies targeted to specific isoforms of the insect steroid hormone receptor (the ecdysone receptor, EcR) will be used to determine which form of the receptor is expressed by glial cells. This is envisioned as a first step toward identifying steroid-regulated genes involved in regulation of the glial cytoskeleton and glial cell adhesion molecules.Previous studies of metamorphosis of the insect nervous system have focused exclusively on neurons. This project will provide new information about the developmental modulation of glial cell cytoarchitecture and glial cell adhesivity during the postembryonic life of insects. The results are likely to generalize to all arthropods and, because the regulation of cell "stickiness" and cell shape are fundamental attributes of all multicellular organisms, to other animals as well.