Evolutionary adaptation of visual pigments in geckos for their photic environment
Evolutionary adaptation of visual pigments in geckos for their photic environment
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DOI：
10.1126/sciadv.abj1316
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发表时间：
2021-10-01
期刊：
影响因子：
13.6
通讯作者：
Yamashita, Takahiro
中科院分区：
文献类型：
--
作者：
Kojima, Keiichi;Matsutani, Yuki;Yamashita, Takahiro
脊椎动物通常只有一种用于暗视的视杆和多种类型的视锥用于明视。值得注意的是，夜间活动的壁虎将祖先的光感受器细胞转化为含有视紫红质而是视锥色素的视杆，随后，白天的壁虎又将这些视杆转化为含有视锥色素的视锥细胞。视杆的低背景噪声是暗视视觉高灵敏度的基础，低背景噪声源于视紫红质的自发激活率远低于视锥色素的自发激活率。在这里，我们发现夜间的壁虎锥体色素降低了它们模拟视紫红质的自发激活率，而白天的壁虎锥体色素恢复的比率与典型的锥体色素相似。我们还确定了与自发激活率变化有关的氨基酸残基。因此，我们得出结论，壁虎在昼夜和夜间之间的转换不仅需要光感受器的形态转化，而且还需要调节视觉色素的自发激活率。
Vertebrates generally have a single type of rod for scotopic vision and multiple types of cones for photopic vision. Noteworthily, nocturnal geckos transmuted ancestral photoreceptor cells into rods containing not rhodopsin but cone pigments, and, subsequently, diurnal geckos retransmuted these rods into cones containing cone pigments. High sensitivity of scotopic vision is underlain by the rod's low background noise, which originated from a much lower spontaneous activation rate of rhodopsin than of cone pigments. Here, we revealed that nocturnal gecko cone pigments decreased their spontaneous activation rates to mimic rhodopsin, whereas diurnal gecko cone pigments recovered high rates similar to those of typical cone pigments. We also identified amino acid residues responsible for the alterations of the spontaneous activation rates. Therefore, we concluded that the switch between diurnality and nocturnality in geckos required not only morphological transmutation of photoreceptors but also adjustment of the spontaneous activation rates of visual pigments.