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，即神经细胞的产生和整合进入成体神经系统，在脊椎动物中是众所周知的。然而，相比之下，在许多无脊椎动物群体中，这种现象仍然没有完全被记录下来。这也适用于最多样化的节肢动物谱系，其详细数据仅在十足类甲壳类动物中可用，对一些昆虫的详细数据较少。在这个项目中，作为十足类甲壳类动物代表的海蜘蛛和小龙虾的成体神经发生过程将在细胞系谱水平上进行研究。体外和体内技术将与(延时)共聚焦成像和3D重建相结合。对小龙虾的研究的一个主要目标是澄清第一代神经前体是否从特定的血细胞招募而来，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。这将突出从中胚层起源的细胞到神经细胞类型的显着转分化，这是教科书上关于外胚层细胞命运的经典例子。另一方面，对海蜘蛛的研究将首先明确地证明，最近的发现有力地表明，这些动物的神经起源过程确实持续到成年后的整个生活。随后的实验将旨在更好地描述神经前体、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，将根据进化背景对海蜘蛛和小龙虾成体神经发生系统之间的潜在相似性进行严格的评估和评估。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。由于海蜘蛛的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干细胞物种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.