Hunt D M, Fitzgibbon J, Slobodyanyuk S J, Bowmaker J K
Department of Molecular Genetics, University College London, U.K.
Vision Res. 1996 May;36(9):1217-24. doi: 10.1016/0042-6989(95)00228-6.
Lake Baikal in Eastern Siberia is the deepest and one of the largest and most ancient lakes in the world. However, even in the deepest regions, oxygenation levels do not fall below 75-80% of the surface levels. This has enabled a remarkable flock of largely endemic teleost fish of the sub-order Cottoidei to colonize all depth habitats. We have previously shown that species that occupy progressively deeper habitats show a blue shift in the peak wavelength of absorbance (lambda max) of both their rod and cone visual pigments; for the rod pigments, a number of stepwise shifts occur from about 516 nm in littoral species to about 484 nm in abyssal species. By sequencing the rod opsin gene from 11 species of Baikal cottoids that include representatives from all depth habitats, we have been able to identify four amino acid substitutions that would account for these shifts. The effect of each substitution on lambda max is approximately additive and each corresponds to a particular lineage of evolution.
位于西伯利亚东部的贝加尔湖是世界上最深、最大且最古老的湖泊之一。然而，即便在最深的区域，氧合水平也不会降至表层水平的75 - 80%以下。这使得一群引人注目的、主要为亚目杜父鱼亚目的特有硬骨鱼得以在所有深度的栖息地中繁衍。我们之前已经表明，占据逐渐更深栖息地的物种，其视杆和视锥视觉色素的吸收峰值波长（λmax）会出现蓝移；对于视杆色素而言，从沿岸物种的约516纳米到深海物种的约484纳米会出现多次逐步变化。通过对11种贝加尔湖杜父鱼的视杆视蛋白基因进行测序，这些杜父鱼包括来自所有深度栖息地的代表物种，我们得以确定四个氨基酸替换，这些替换可以解释这些变化。每个替换对λmax的影响大致是累加的，并且每个替换都对应于一个特定的进化谱系。
