Evolution and development of glial cells in Platynereis dumerilii (Annelida)

动物神经系统的进化起源是一个高度相关且仍有激烈争论的话题。具体地说，复杂的中枢神经系统在双边进化过程中是一次还是几次独立进化的问题到目前为止还没有答案。有趣的是，过去对这一主题的研究大多集中在神经细胞的特征上。到目前为止，他们忽略了另一种重要的细胞类型，即已知存在于大多数双边神经系统中的神经胶质细胞。有趣的是，最近的许多研究表明，神经胶质细胞对神经系统的功能和发育与神经元本身一样重要。然而，后口动物和原口动物中的神经胶质细胞是共同起源的，还是共同进化的，目前还不清楚。此外，由于缺乏数据和同源性陈述，对神经胶质细胞类型的一致命名仍然缺乏。随着对果蝇(蜕皮纲)和哺乳动物(后口纲)的研究，到目前为止，关于胶质细胞功能和基因表达的数据只适用于肾形动物的两个主要树枝。值得注意的是，关于Lophotrochozoa--第三个重要的肾动物主要支系--的数据仍然缺失。因此，为了了解双侧胶质细胞的进化，迫切需要全面的Lophotrochozoa数据集。因此，为了深入了解Lophotrochozoa中胶质细胞的多样性，我建议在模式动物Platynereis umerilii中研究胶质细胞及其发育。为此，我想使用全面的方法，包括原位杂交技术和免疫组织化学染色定制的以及标准的抗体。此外，我们希望应用免疫金标记法、透射电子显微镜和随后在超微结构水平上的3D分析来研究胶质细胞、它们的超微结构以及它们在扁平线虫不同发育阶段的命运。通过这一广泛的方法，该项目将提供急需的数据、一组与Lophotrochozoan胶质细胞相关的基因和神经胶质细胞特有的定制抗体，以及对Lophotrochozoan神经胶质细胞进化的初步见解。此外，我们将为胶质细胞研究中进一步的比较方法奠定基础。此外，这个项目将允许澄清一般的比拉特里亚神经胶质细胞的同源性。

The evolutionary origin of animal nervous systems is a highly relevant and still intensely debated topic. Specifically, the question whether complex centralized nervous systems evolved once or several times independently during bilaterian evolution remains unanswered so far. Interestingly, most of the investigations dealing with this topic in the past solely focussed on characteristics of the neuronal cells. So far, they leave out another important cell type, which is known to be present in most bilaterian nervous systems – the glia cells. Interestingly, numerous recent studies have shown that glial cells are as important for the nervous system function and development as the neurons themselves. Nevertheless, it is still unknown whether glial cells in deuterostomes and protostomes – the two main clades of Nephrozoa – share a common origin or have evolved convergently. Furthermore, a consistent nomenclature of glia cell types is still missing due to the lack of data and homology statements. With the work on Drosophila (Ecdysozoa) and mammals (Deuterostomia), data on glial cell function and gene expression are so far only available for two of the tree main clades of Nephrozoa. Notably, data for Lophotrochozoa – the third important nephrozoan main clade - are still missing. Hence, comprehensive datasets for Lophotrochozoa are highly needed to understand the evolution of bilaterian glia cells. To gain insights into glia cell diversity in Lophotrochozoa, I therefore propose to work on glia cells and their development in the model annelid Platynereis dumerilii. For this purpose, I want to use comprehensive methods including in situ hybridization techniques and immunohistochemical stainings with customized as well as standard antibodies. Furthermore, we want to apply ImmunoGold labelling, transmission electron microscopy (TEM) and subsequent 3D analyses on ultrastructural level to investigate the glia cells, their ultrastructure as well as their fate in different stages of Platynereis. With this broad approach, the project will provide highly needed data, a set of lophotrochozoan glia relevant genes and glia specific customized antibodies and first insights into lophotrochozoan glia evolution. Furthermore, we will build up the backbone for further comparative approaches in glia cell research. Additionally, this project will allow a clarification concerning the homology of glia cells in Bilateria in general.