Opsin Evolution in Stomatopod Crustaceans: Molecular Investigations of a Complex Visual System

感觉系统的进化，特别是视觉系统的进化，是生态学家、生理学家、神经生物学家和进化生物学家的一个具有根本意义的研究领域。特别是，视觉色素（吸收光的分子，在许多方面决定视觉灵敏度和色觉的主要特征）的进化长期以来一直作为理解基因和蛋白质如何进化的模型系统，蛋白质的结构特征如何影响功能，以及感觉系统如何进化调整以满足不同物种的功能需求。对口足类甲壳类动物或螳螂虾的研究一直是这项工作的核心。这些海洋动物进化出了独特复杂的视觉系统，这在动物界是无与伦比的。它们拥有所有动物中最复杂的色彩视觉系统，基于16种或更多不同的视觉色素（比任何其他动物群体的已知数量都要多两倍以上）。这些色素是光感受器类别中的光捕获分子，专门用于感知从深紫外线到远红色的光波长。因此，口足类动物一直是色觉、栖息地视觉适应、颜色和极化信号以及视觉系统进化等研究的热门对象。它们的视觉色素通常被视为理解所有生物体中蛋白质设计和功能的分子机器模型。这个项目汇集了一个由视觉科学家、分子生物学家和进化生物学家组成的团队，研究螳螂虾的视觉是如何在分子水平上进化的，了解它们众多种类的光感受器是如何在进化过程中变得专业化的，并发现口足类动物的进化进步是如何实际运作的，以改善视觉功能。因为口足类动物有这么多不同类型的视觉色素，都是基于一种叫做视蛋白的蛋白质，它们提供了一个天然的实验室来研究功能的多样化，并了解这些视蛋白的变化是如何降低到特定氨基酸取代的水平，从而促进新的视觉色素的进化，产生新的光谱类别，并调整不同物种的视觉功能以适应特定的栖息地。本项目以选定的螳螂虾视网膜视蛋白为模型系统，研究物种内、物种间和栖息地之间的遗传多样性，确定调节其视觉色素的分子机制，并建立现代多样性的进化机制。这项工作将涉及尖端的方法，包括基因测序、基因表达的细胞鉴定、系统发育多样化的计算评估和分子建模。这些结果将为理解视觉功能的进步和视觉科学的医学和技术方面的鼓舞人心的进步提供新的和重要的基础。这项工作将包括博士后、研究生和本科生的培训，pi将在学校和非科学专业会议上进行公开演讲，并计划为教科书开发和博物馆展览做出贡献。

Evolution of sensory systems, and specifically the evolution of visual systems, is a research area of fundamental significance to ecologists, physiologists, neurobiologists, and evolutionary biologists. In particular, the evolution of visual pigments (the molecules that absorb light and in many ways determine primary features of visual sensitivity and color vision) has long served as a model system for understanding how genes and proteins evolve, how structural features of proteins affect function, and how sensory systems evolutionarily adjust to meet the functional requirements of different species. Research on stomatopod crustaceans, or mantis shrimps, has been central to this work. These marine animals have evolved a uniquely complex visual system, one that is unparalleled in the animal kingdom. They possess the most complicated systems of color vision of any animals, based on 16 or more different visual pigments (greater than the number known for any other animal group by a factor of more than two). These pigments are the light-capturing molecules in photoreceptor classes specialized to sense wavelengths of light from the deep ultraviolet to the far red. Stomatopods, therefore, have been favored subjects for studies of color vision, visual adaptation to habitat, color and polarizational signaling, and evolution of visual systems. Their visual pigments are often viewed as models of molecular machines for understanding protein design and function in all organisms.This project brings together a team of vision scientists, molecular biologists, and evolutionary biologists to investigate how mantis shrimp vision has evolved at the molecular level, to learn how their numerous classes of photoreceptors have become specialized over evolutionary time, and to discover how the evolutionary advances made by stomatopods actually operate to improve visual function. Because stomatopods have so many different types of visual pigments, all based on a single class of proteins called opsins, they provide a natural laboratory within which to study diversification of function and to learn how changes in these opsin proteins down to the level of specific amino acid substitutions foster the evolution of new visual pigments, produce new spectral classes, and tune the visual functions of different species to particular habitats. Using the opsins in retinas of selected species of mantis shrimps as a model system, the research of this project will characterize the genetic diversity within and among species and between habitats, identify the molecular mechanisms used to tune their visual pigments, and establish how the modern diversity evolved. The work will involve cutting-edge approaches, including genetic sequencing, cellular identification of gene expression, computational assessment of phylogenetic diversification, and molecular modeling. The results will serve as new and significant underpinnings for advances in understanding visual function and for inspiring advances in medical and technological aspects of vision science. The work will involve the training of post-doctoral fellows, graduate students and undergraduates as part of the project, and the PIs will give public lectures at schools and non-scientific professional meetings and plan to contribute to textbook development and museum exhibitions.