Evolution of photoreceptors as illuminated by fossils and development

化石和发展揭示的光感受器的进化

• 批准号: RGPIN-2019-04825
• 负责人: Allison, WTed
• 金额: $ 2.62万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=714948
• 关键词: Evolution; photoreceptors; illuminated; fossils; development

The long-term Aim of my Program is to make foundational insights into photoreceptor evolution and visual ecology. We accomplish this principally by comparing the development (evo-devo) of photoreceptors between disparate vertebrates and between ontogenetic stages. We often use zebrafish as a platform to experimentally test the novel hypotheses generated from exploring other more interesting animals (jawless fishes, migrating fishes, crustaceans). In the coming years we will investigate provocative new ideas emerging from our recent work: The majority of Mammalian rod photoreceptors develop and evolved from cone photoreceptors, especially from the short-wavelength-sensitive (SWS- or UV-) cones; To refine cell type homology concepts, and to test if rod photoreceptors evolved from SWS cones, we will compare the propensity of the 4 cone types to transdifferentiate into rods; The identity and evolution of rods vs. cones can be revealed in hagfish (thus revealing early vertebrate evolution) by assessing expression of key developmental genes alongside incisively testing hagfish gene function in our zebrafish platform. My HQP will be well-positioned to make foundational insights into the biology and evolution of the duplex retina, i.e. the biology behind possessing both rods and cones that has empowered the immense success of the vertebrate radiation. Further, we remain puzzled and fascinated by the elaborately arrayed patterns of photoreceptors observed in the retinas of most animals (though lost in mammals). Our genetic approaches in zebrafish continue to reveal mechanisms of this photoreceptor mosaic formation and mosaic functions. To complement this, we will expand our Program now to compare to the development of photoreceptor arrays in crustaceans. Ontogenetic changes in ommatidia and photoreceptor patterning therein has striking (presumably convergent?) similarities to those of fish photoreceptors. Decapod crustaceans (crabs, crayfish, etc.) of special interest have square (“reflecting mirror box”) ommatidia, however they BEGIN larval life with the familiar hexagonal ommatidia. Amazingly, and unlike in vertebrates, these photoreceptor morphologies are well-preserved in the fossil record. We will compare fossils to the ommatidia and photoreceptor complement in extant crabs and shrimps, with special focus on arrays that change during ontogeny and/or have regional specialization such that multiple morphologies occur simultaneously in each individual eye. Understanding the evolution of vertebrate photoreceptors is hampered by lack of fossil record. My HQP overcome this challenge via two strategies: First: by comparing the developmental program that produces photoreceptors, we will uniquely reveal ancient homologies. Second: we will identify the pitfalls and opportunities of this evo-devo approach, as applied to sensory systems, by interrogating a developmental system that can be calibrated against fossil photoreceptors.

我的项目的长期目标是对光感受器进化和视觉生态学进行基础性的研究。我们主要通过比较不同脊椎动物和个体发育阶段之间光感受器的发育（进化-发展）来完成这一任务。我们经常用斑马鱼作为实验平台，来检验从探索其他更有趣的动物（无颌鱼类、迁徙鱼类、甲壳类动物）中产生的新假设。在接下来的几年里，我们将研究从我们最近的工作中出现的具有挑衅性的新想法：