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，是对生态学家、生理学家、神经生物学家和进化生物学家具有重要意义的研究领域。 特别是，视觉色素（吸收光的分子，在许多方面决定视觉敏感度和色觉的主要特征）的进化长期以来一直是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一种独特的复杂视觉系统，这在动物王国中是无与伦比的。 它们拥有任何动物中最复杂的色觉系统，基于16种或更多不同的视觉色素（比任何其他动物群体已知的数量大两倍以上）。 这些色素是感光器中的光捕获分子，专门用于感知从深紫外到远红的光波长。 因此，口足类动物一直是研究颜色视觉，视觉适应栖息地，颜色和偏振信号，视觉系统的进化的青睐科目。 他们的视觉色素通常被视为分子机器的模型，用于理解所有生物体中蛋白质的设计和功能。这个项目汇集了一个视觉科学家，分子生物学家和进化生物学家的团队，以研究螳螂虾视觉如何在分子水平上进化，了解他们的众多类别的光感受器如何在进化过程中变得专业化，并发现口足类动物的进化进步实际上如何改善视觉功能。 因为口足类动物有如此多不同类型的视色素，所有这些都基于一类称为视蛋白的蛋白质，它们提供了一个天然的实验室，在其中研究功能的多样化，并了解这些视蛋白质的变化如何降低到特定氨基酸取代的水平，促进新视色素的进化，产生新的光谱类别，并将不同物种的视觉功能调整到特定的栖息地。 本项目的研究将利用选定种类的螳螂虾视网膜中的视蛋白作为模型系统，描述物种内、物种间和栖息地间的遗传多样性，确定用于调节其视色素的分子机制，并确定现代多样性是如何演变的。 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，系统发育多样性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以及视觉科学的医学和技术方面的进步提供新的重要基础。 作为该项目的一部分，这项工作将包括培训博士后研究员、研究生和本科生，项目研究员将在学校和非科学专业会议上发表公开演讲，并计划为教科书编写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.