Comparative and Computational Approaches to the Evolution of Myelin

对威胁的快速行为反应对于遭受高捕食风险的动物的生存至关重要。有两种方法可以缩短威胁性刺激和逃避反应之间的延迟，它们都是通过增加沿神经轴突的神经冲动传导速度：轴突巨人症和轴突周围的髓鞘。尽管髓磷脂在脊椎动物中最为人所知，但在两种甲壳类动物中也发现了髓磷脂。这两个无脊椎类群提供了了解髓鞘结构-功能关系的机会，因为：1)可以比较密切相关的有髓鞘和无髓鞘形式；2)神经细胞可以从一个个体重新识别到另一个个体，3)髓磷脂的发育可以在所有发育阶段在已识别的细胞中被追踪。在这个项目中，生理学和计算方法将被用于两种甲壳类动物群体：malacostraca和calanoid桡足类的髓磷脂结构-功能比较分析。髓磷脂在这两个群体中独立进化，但它在结构和起源上不同，但在两者之间有许多共同的特征。一些甲壳类动物在发育过程中从完全无髓鞘神经系统过渡到完全有髓鞘神经系统，从而为研究不完全形成的髓鞘中的神经冲动传导提供了一个很好的模型。研究桡足类与马拉孔甲类髓磷脂在结构和功能上的共性，将为研究脊椎动物髓磷脂的功能和进化提供新的思路。这项研究将开始回答髓磷脂如何以及为什么进化的问题。该项目将培养跨学科生物学和团队研究的年轻本科科学家，建立科学、技术、工程和数学的多样性；并为教育和数据挖掘目的提供公众访问微观图像的途径。该项目的博士后培训生将学习透射电子显微镜材料的制备和检查，细胞外电生理刺激和记录技术，以及神经元功能的计算建模。

Rapid behavioral responses to a threat are critical for the survival of animals subjected to high predation risk. Two methods have evolved to shorten the delay between a threatening stimulus and an escape response, both by increasing the conduction velocity of nerve impulses along nerve axons: axon gigantism and myelin sheaths around the axons. Although myelin is best known in vertebrates, it is also found in two crustacean groups. These two invertebrate groups provide opportunities to understand structure-function relationships in myelin because: 1) it is possible to compare closely-related myelinated and non-myelinated forms; 2) nerve cells can be re-identified from one individual to the next, and 3) development of myelin can be tracked in identified cells through all developmental stages. In this project, physiological and computational approaches will be used in a comparative structure-function analysis of myelin in the two crustacean groups: the malacostraca and the calanoid copepods. Myelin has evolved independently in these two groups, yet it shares many features between the two, while being distinct in structure and origin. Some crustaceans transition from completely non-myelinated to fully myelinated nervous systems during development, and thus provide a good model in which to investigate nerve impulse conduction in incompletely formed myelin. Characterizing the commonalities in structure and function for myelin in copepods vs malacostracans will provide new insights into the function and evolution of vertebrate myelin. This study will start answering the question of how and why myelin evolved.The project will train young undergraduate scientists in interdisciplinary biology and team research, build diversity in science, technology, engineering and math; and provide public access to microscopic images for educational and data mining purposes. Postdoctoral trainees on the project will be educated in the preparation and examination of material for transmission electron microscopy, extracellular electrophysiological stimulation and recording techniques, and computational modeling of neuronal functioning.