Comparison of life-long neurogenic processes in sea spiders and crustaceans - indications for an ancestral adult neurogenic system in Arthropoda?

成体神经发生，即神经细胞在成体神经系统中的产生和整合，在脊椎动物中是众所周知的。然而，相比之下，这种现象在许多无脊椎动物群体中仍未得到完整的记录。这也适用于最多样化的动物谱系节肢动物，这方面的详细数据只适用于十足甲壳类动物，一些昆虫的数据较少。在本项目中，将在细胞谱系水平上研究作为十足甲壳类动物代表的海蜘蛛和小龙虾的成体神经发生过程。体外和体内技术的结合将与（延时）共聚焦成像和3D重建相结合。对小龙虾进行研究的一个主要目标是阐明第一代神经前体是否来自特定的血细胞，这些血细胞代表先天免疫系统的一个组成部分，是造血干细胞的后代。这将突出中胚层细胞向神经细胞类型的显著反分化，这是外胚层细胞命运的经典教科书例子。另一方面，对海蜘蛛的研究首先将明确地证明神经发生过程——正如最近的研究结果所强烈表明的那样——确实会持续到这些动物的整个成年生活。随后的实验将旨在更好地描述神经前体，它们的细胞分裂和细胞迁移动力学，以及分化的神经细胞类型。此外，海蜘蛛和小龙虾的成年神经发生系统之间的潜在相似性将在进化背景下进行严格评估和评估。将确定所涉及的结构和过程是否可以被认为是同源的，即具有共同的进化起源。由于海蜘蛛谱系是节肢动物进化过程中相对较早的分支，这有望揭示节肢动物茎类物种中祖先终身神经发生系统的重要见解。

Adult neurogenesis, i.e., the production and integration of neural cells into adult nervous systems, is well known in vertebrates. By comparison, however, this phenomenon remains incompletely documented in numerous invertebrate groups. This holds also for the most diverse animal lineage Arthropoda, for which detailed data are only available in decapod crustaceans and to a lesser degree for some insects.In this project, adult neurogenic processes in sea spiders (Pycnogonida) and crayfish as representatives of decapod crustaceans will be investigated at the cell genealogical level. A combination of in-vitro and in-vivo techniques will be applied in conjunction with (time-lapse) confocal imaging and 3D reconstruction.A major goal of the investigations on crayfish is to clarify whether first-generation neural precursors are recruited from specific blood cells, which represent a component of the innate immune system and are descendents from hematopoietic stem cells. This would highlight a remarkable trans-differentiation from cells of mesodermal origin into neural cell types that are classical textbook examples for an ectodermal cell fate.The studies on sea spiders, on the other hand, will first of all seek to unequivocally prove that neurogenic processes - as strongly indicated by recent findings - do continue throughout adult life of these animals. Subsequent experiments will then aim to provide a better characterization of the neural precursors, their cell division and cell migration dynamics, and of the differentiating neural cell types.Moreover, potential similarities between the adult neurogenic systems of sea spiders and crayfish will be critically assessed and evaluated against an evolutionary background. It will be determined whether the involved structures and processes can be considered as being homologous, i.e., to have a common evolutionary origin. Since the sea spider lineage is a relatively early offshoot during arthropod evolution, this promises to reveal important insights into an ancestral life-long neurogenic system in the arthropod stem species.