Ultrastructural and immunohistochemical studies of the ontogeny of the nervous system and the mesoderm in Enteropneusta and Pterobranchia in order to elucidate deuterostome evolution.

对肠肺和翼鳃亚纲神经系统和中胚层的个体发育进行超微结构和免疫组织化学研究，以引发后口动物的进化。

• 批准号: 50294992
• 负责人: Dr. Thomas Stach
• 金额: --
• 依托单位: Forschungsgruppe Elektronenmikroskopie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/50294992?language=en
• 关键词: Ultrastructural; immunohistochemical; studies; ontogeny; nervous

Morphological and molecular data support different phylogenetic hypotheses of deuterostome taxa and therefore infer contrasting evolutionary character evolution. Many of the supposedly morphological “key characters” have not been adequately studied in proper ontogenetic or structural detail. In the present project, we analyze the ontogeny of morphological characters that have been considered important for deuterostome evolution utilizing computer assisted 3D-reconstruction based on serial transmission electron micrographs in combination with confocal laser scanning microscopy of immunolabeled specimens. We have so far documented the neurulation of the collar cord in an enteropneust and revealed that the collar cord is much more complex than was hitherto believed. E.g., areas of neuronal somata and neuropil are clearly organized in concise patterns, a intimate relation between the asymmetric proboscis pore and the collar cord exists, and we discovered a distinct gland in the mid-dorsal line that develops from a glandular ring around the entire collar. Our database allows the reconstruction of peripheral nerves in the branchial region along with coelomic cavities, blood vessels, skeletal elements, and musculature. Using serially sectioned specimens fixed for electron microscopy, we could for the first time observe the ontogenetic primordium of the pericard, corresponding to the right protocoel of other deuterostomes. Based on our detailed anatomical studies, we could find no further support for the often-quoted primary homology hypothesis between the post-anal tail of enteropneusts and the chordate tail. In the successfully collected two species of pterobranchs, we just started our morphological analyses and found similarities in the dorsal ganglion to the organization of chordate central nervous systems based on confocal laser scanning microscopical investigation of the serotonergic nervous system. Transmission electron microscopy of developmental stages of pterobranchs that were also successfully sampled, are scheduled for analysis later this year, as are studies of adult structures. In summary, this project has already yielded important results, has successfully completed acquisition of biological samples, and has therefore the potential to fulfill all goals aimed for in the original project, especially after Sabrina Kaul a PhD candidate ideally trained for this project joined the project.

形态和分子数据支持不同的系统发育假说的后口类类群，因此推断对比进化性状的进化。许多被认为是形态学上的“关键特征”还没有在适当的个体发育或结构细节方面得到充分的研究。在本项目中，我们分析了个体发育的形态特征，已被认为是重要的后口进化利用计算机辅助三维重建的基础上，结合共聚焦激光扫描显微镜的免疫标记标本的连续透射电子显微镜。到目前为止，我们已经证明了肠呼吸中颈索的神经形成，并揭示了颈索比迄今所认为的要复杂得多。例如，在一个示例中，神经元胞体和神经毡区域以简洁的模式清晰地组织起来，不对称的吻孔和领索之间存在密切的关系，并且我们发现背中线有一个明显的腺体，它是从整个衣领周围的腺环发育而来的。我们的数据库可以重建周围神经的鳃区域沿着体腔，血管，骨骼元素，和肌肉组织。利用连续切片的电镜标本，我们可以观察到的pericard的个体发育原基，对应于其他后口动物的右原体腔。根据我们详细的解剖学研究，我们不能找到进一步的支持，经常引用的主要同源性之间的假设，肛门后尾的肠寄生虫和脊索动物的尾巴。在成功收集的两种翼鳃类中，我们刚刚开始我们的形态学分析，并发现背神经节的相似之处，脊索中枢神经系统的组织的基础上共聚焦激光扫描显微镜调查的神经元能神经系统。同样成功取样的翼鳃类动物发育阶段的透射电子显微镜检查，计划在今年晚些时候进行分析，对成年动物结构的研究也是如此。总之，该项目已经取得了重要成果，成功地完成了生物样本的采集，因此有可能实现原项目的所有目标，特别是在Sabrina Kaul博士候选人加入该项目之后。