Comparative aspects of persistent neurogenesis in the central olfactory pathway of adult malacostracan crustaceans.

小龙虾大脑的中央嗅觉通路的特征在于持续的、终身的神经发生。成人神经发生由大脑表面的神经发生小生境驱动，该小生境产生第一代前体细胞。这些细胞离开小生境，并沿着沿着向前和中间定向的迁移流向前部和中间增殖区移动，两者都与中央嗅觉通路相关。在它们的迁移过程中，细胞经历额外的有丝分裂并进化成第二代和第三代前体细胞。内侧增殖区产生新的局部嗅觉中间神经元，而外侧增殖区产生嗅觉投射神经元。该系统中的细胞机制统称为中脑增殖系统（DPS），与哺乳动物中驱动成年神经发生的系统具有很强的相似性。在这些动物中，一个神经发生的小生境，脑室下区，产生后代迁移沿着向嗅球的吻侧迁移流的神经元整合到现有的神经元回路。这个项目的目的是在一个广泛的比较背景和进化背景下研究甲壳动物嗅觉系统中持续神经发生的现象。我们想知道，为小龙虾描述的成年神经发生机制是否也适用于其他软甲介类甲壳动物，并将分析可能的变化，以深入了解该系统的可能功能。通过这种比较方法，我们将探索甲壳类动物为完成任务而进化的解决方案-终身神经发生。为此，我们将研究10个具有代表性的所有主要类群的软甲藻与免疫组织化学技术，在体内标记有丝分裂标记物，脉冲追踪实验和透射电子显微镜的组合。具体而言，我们将分析A）DPS组件的一般安排; B）神经发生生态位的超微结构; C）迁移流中定向运动的方面; D）新的嗅觉中间神经元整合到中央嗅觉通路中; E）与外侧前脑中的半椭圆体相关的持续神经发生。这项研究将为未来的项目奠定基础，该项目将更深入地探索适合模型甲壳动物的持续神经发生的功能，特别是关于新神经元如何连接到功能性成年嗅觉系统网络的问题。

The central olfactory pathway of the crayfish brain is characterized by persistent, life-long neurogenesis. Adult neurogenesis is driven by a neurogenetic niche on the surface of the brain that generates 1st generation precursor cells. These cells leave the niche and move along an anteriorly and a medially directed migratory stream towards an anterior and a medial proliferation zone, both associated with the central olfactory pathway. During their migration, the cells undergo additional mitoses and evolve into 2nd and 3rd generation precursor cells. The medial proliferation zone contributes new local olfactory interneurons whereas the lateral proliferation zone generates olfactory projection neurons. The cellular machinery in this system that is collectively called the deutocerebral proliferative system (DPS) displays strong similarities to the system that drives adult neurogenesis in mammals. In these animals, a neurogenetic niche, the subventricular zone, generates progeny that migrate along the rostral migratory streams towards the olfactory bulb where the neurons are integrated into existing neuronal circuits. This projects sets out to examine the phenomenon of persistent neurogenesis in the crustacean olfactory system in a broad comparative context and against an evolutionary background. We want to know if the mechanisms of adult neurogenesis described for the crayfish hold for other malacostracan crustaceans too and will analyse possible variations in order to gain insights into the possible function of this system. With this comparative approach we will explore the solutions which crustaceans evolved for the task - life-long neurogenesis. To that end we will study ten representative of all major taxa of Malacostraca with immunohistochemical techniques, in vivo labelling with combinations of mitosis markers, pulse-chase experiments and transmission electron microscopy. Specifically, we will analyze A) general arrangement of the DPS components; B) ultrastructure of the neurogenetic niche; C) aspects of the directed movement in the migratory streams; D) integration of the new olfactory interneurons into the central olfactory pathway; E) persistent neurogenesis associated with the hemiellipsoid bodies in the lateral protocerebrum. This study will lay the foundations for a future project that will in more depth explore the function of persistent neurogenesis in suited model crustaceans specifically with regard to the question how the new neurons are wired up into the network of the functional, adult olfactory system.