The central nervous system of velvet worms (Onychophora) - Shedding light on the evolution of the panarthropod brain

节肢动物，可以说是世界上最成功的动物，由于其身体的复杂性，几个世纪以来一直吸引着研究人员。神经系统是节肢动物机体的重要特征之一，它在很大程度上反映了解剖结构的复杂性。了解这些令人困惑的器官的进化需要对节肢动物本身及其最近的亲属-- Onychophora（天鹅绒蠕虫）和Tardigrada（水熊）进行调查，它们共同组成了Panarthropoda。作为缓步动物和节肢动物或节肢动物的姐妹类群，有爪动物在理解泛节肢动物形态特征的进化中起着关键作用。然而，尽管它们具有重要的系统发育地位，但它们的神经系统，特别是大脑，在很大程度上研究不足。因此，拟议项目的目的是（一）澄清现有的争议，围绕命名和假定的同源性的onychophoran大脑的节肢动物，（ii）numerous未描述的结构和功能的onychophoran大脑。基于同步辐射的X射线显微计算机断层扫描和纳米焦点X射线源断层扫描数据集的三维重建的基础上-除了广泛的神经解剖学方法，如各种抗体标记和神经元追踪-将设计一个三维的onychophoran大脑的“图集”。此外，这项研究将照亮onychophoran大脑超越形态特征，此外，调查潜在的神经发生在成年onychophorans，功能迄今未知的这些动物。此外，不同的大脑区域的发展将被检查，因为这将产生宝贵的证据大脑结构的起源，因此，将有助于绘制假定的同源性节肢动物。所获得的数据将是有价值的，不仅为了解解剖的onychophoran大脑本身，但此外，为阐明的进化的前部的中枢神经系统在泛节肢动物。因此，所获得的结果将在很大程度上有助于我们了解有趣的节肢动物神经系统的进化。

Arthropods, arguably the most successful animals worldwide, have fascinated researchers for centuries due to the complexity of their bodies. One of the most important features of the arthropod body is their nervous system, which reflects the anatomical complexity to a great extent. Understanding the evolution of these puzzling organs requires investigations of both arthropods themselves and their closest relatives - Onychophora (velvet worms) and Tardigrada (water bears), which all together compose the Panarthropoda. As sister group to either tardigrades plus arthropods or arthropods alone, onychophorans play a key role for understanding the evolution of morphological traits within panarthropods. Nevertheless, despite their significant phylogenetic position, their nervous system, in particular the brain, is largely understudied. Therefore, the aims of the proposed project are to (i) clarify existing controversies surrounding the nomenclature and presumptions of putative homologies of the onychophoran brain to that of arthropods, and (ii) characterise numerous undescribed structures and features of the onychophoran brain. On the basis of 3D reconstructions of synchrotron radiation-based X-ray micro-computed tomographic and nanofocus X-ray source tomographic data sets - in addition to a wide range of neuroanatomical methods, such as a variety of antibody labelling and neuronal tracing - a three-dimensional "atlas" of the onychophoran brain will be designed. Moreover, this study will illuminate the onychophoran brain beyond morphological characters and, in addition, investigate potential neurogenesis in adult onychophorans, a feature so far unknown for these animals. Furthermore, the development of distinct brain regions will be examined as this will yield invaluable evidence for the origin of cerebral structures and, therefore, will help to draw putative homologies to arthropods. The obtained data will be valuable not only for understanding the anatomy of the onychophoran brain itself but, in addition, for elucidating the evolution of the anterior part of the central nervous system in panarthropods. The obtained results will therefore largely contribute to our understanding of the evolution of the intriguing arthropod nervous systems.