Abstract:
The last common ancestor of cephalopods and vertebrates lived about 580 million years ago, yet coleoid cephalopods, comprising squid, cuttlefish and octopus, have evolved an extraordinary behavioural repertoire that includes learned behaviour and tool utilization. These animals also developed innovative advanced defence mechanisms such as camouflage and ink release. They have evolved unique life cycles and possess the largest invertebrate nervous systems. Thus, studying coleoid cephalopods provides a unique opportunity to gain insights into the evolution and development of large centralised nervous systems. As non-model species, molecular and genetic tools are still limited. However, significant insights have already been gained to deconvolve embryonic brain development. Even though coleoid cephalopods possess a typical molluscan circumesophageal bauplan for their central nervous system, aspects of its development are reminiscent of processes observed in vertebrates as well, such as long-distance neuronal migration. This review provides an overview of embryonic coleoid cephalopod research focusing on the cellular and molecular aspects of neurogenesis, migration and patterning. Additionally, we summarize recent work on neural cell type diversity in embryonic and hatchling cephalopod brains. We conclude by highlighting gaps in our knowledge and routes for future research.
摘要:
头足类动物和脊椎动物的最后一个共同祖先生活在大约5.8亿年前,然而胚状体头足类动物,包括鱿鱼,乌贼和章鱼,已经发展出一种非凡的行为方式,包括学习行为和工具利用。这些动物还开发了创新的先进防御机制,例如伪装和墨水释放。它们进化出独特的生命周期,拥有最大的无脊椎动物神经系统。因此,研究coleoid头足类动物提供了一个独特的机会,可以深入了解大型集中神经系统的进化和发展。作为非模型物种,分子和遗传工具仍然有限。然而,已经获得了对胚胎大脑发育进行反卷积的重要见解。即使胚状体头足类动物的中枢神经系统具有典型的软体动物环食管bauplan,它的发展方面让人想起在脊椎动物中观察到的过程,如远距离神经元迁移。这篇综述概述了胚胎类头足类研究,重点是神经发生的细胞和分子方面。迁移和图案。此外,我们总结了最近关于胚胎和孵化头足类大脑中神经细胞类型多样性的工作。最后,我们强调了我们知识和未来研究路线的差距。