Genomic and Spectral Visual Adaptation in Southern Leopard Frogs during the Ontogenetic Transition from Aquatic to Terrestrial Light Environments
Genomic and Spectral Visual Adaptation in Southern Leopard Frogs during the Ontogenetic Transition from Aquatic to Terrestrial Light Environments
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DOI：
10.1101/2021.02.19.432049
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发表时间：
2021-02
期刊：
影响因子：
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通讯作者：
Ryan K. Schott;Rayna C. Bell;E. Loew;Kate N. Thomas;D. Gower;Jeffrey W. Streicher;M. Fujita
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文献类型：
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作者：
Ryan K. Schott;Rayna C. Bell;E. Loew;Kate N. Thomas;D. Gower;Jeffrey W. Streicher;M. Fujita
许多动物有复杂的生命周期，其中幼虫和成虫形式有不同的生态和栖息地，对它们的感觉系统有不同的要求。虽然适应性解耦假说预测生命阶段之间的遗传相关性降低，但感觉系统如何在分子水平上适应生命阶段还没有很好的理解。青蛙是研究这个问题的一个令人信服的系统，因为大多数物种都依赖视觉作为水生蝌蚪和陆地成年人，但这些栖息地呈现出截然不同的光环境。在这里，我们使用全眼转录组测序，以调查南部豹蛙（Lithobates sphenocephalus）的水生蝌蚪和陆生幼蛙之间的差异表达。由于视觉生理学随着光照水平的变化而变化，我们还测试了持续的光照或黑暗暴露如何影响基因表达。我们发现42%的基因在蝌蚪和青少年的眼睛中差异表达，而在光/暗暴露中只有5%。针对一组精心策划的视觉基因的分析揭示了控制视觉功能和发育的基因在生命阶段之间的显着差异表达，包括光谱敏感性和透镜组成。光/暗暴露对一组较小的视觉基因有显着影响。最后，显微分光光度法的光感受器证实的表达结果预测的光谱灵敏度的变化，与适应不同的光环境。总的来说，我们确定了广泛的表达水平的差异，在蝌蚪和幼蛙的眼睛观察到的形态和生理变化，通过变态，以及相应的适应性转变，以优化视觉在水生与陆地环境。
Many animals have complex life cycles where larval and adult forms have distinct ecologies and habitats that impose different demands on their sensory systems. While the adaptive decoupling hypothesis predicts reduced genetic correlations between life stages, how sensory systems adapt across life stages at the molecular level is not well understood. Frogs are a compelling system to study this question in because most species rely on vision as both aquatic tadpoles and terrestrial adults, but these habitats present vastly different light environments. Here we used whole eye transcriptome sequencing to investigate differential expression between aquatic tadpoles and terrestrial juveniles of the southern leopard frog (Lithobates sphenocephalus). Because visual physiology changes with light levels, we also tested how constant light or dark exposure affected gene expression. We found 42% of genes were differentially expressed in the eyes of tadpoles versus juveniles, versus 5% for light/dark exposure. Analyses targeting a curated set of visual genes revealed significant differential expression between life stages in genes that control aspects of visual function and development, including spectral sensitivity and lens composition. Light/dark exposure had a significant effect on a smaller set of visual genes. Finally, microspectrophotometry of photoreceptors confirmed shifts in spectral sensitivity predicted by the expression results, consistent with adaptation to distinct light environments. Overall, we identified extensive expression-level differences in the eyes of tadpole and juvenile frogs related to observed morphological and physiological changes through metamorphosis, and corresponding adaptive shifts to optimize vision in aquatic versus terrestrial environments.