Pronounced heritable variation and limited phenotypic plasticity in visual pigments and opsin expression of threespine stickleback photoreceptors
Pronounced heritable variation and limited phenotypic plasticity in visual pigments and opsin expression of threespine stickleback photoreceptors
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DOI：
10.1242/jeb.078840
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发表时间：
2013-02-01
影响因子：
2.8
通讯作者：
Reimchen, Thomas E.
中科院分区：
文献类型：
--
作者：
Flamarique, Inigo Novales;Cheng, Christiana L.;Reimchen, Thomas E.
脊椎动物的色觉是由视网膜锥光感受器中视觉色素蛋白（视蛋白）的差异表达介导的。许多物种在生命过程中会改变视蛋白的表达，无论是作为发育的一部分还是由于栖息地的变化。后者是表型可塑性的结果，在鱼类中很常见，但其细胞起源和生态意义尚不清楚。在这里，我们使用来自不同光照条件的成年三刺刺鱼来研究视蛋白表达的遗传变异性和表型可塑性。来自清澈水域的鱼具有表达长波长 (LWS) 和中波长 (RH2) 视蛋白的双视锥细胞，每个双视锥细胞成员各有一个。相比之下，来自红光转移湖泊的鱼具有双锥体，其 LWS/LWS 对数 > 95%。所有鱼类都具有主要表达短波长 (SWS2) 视蛋白的单个视锥细胞，但表达 SWS1 视蛋白的紫外线视锥细胞遍布整个视网膜。来自红光转移湖泊的鱼，当转移到清澈的水域时，RH2/LWS 双锥体的含量增加了 2%，尽管双锥体密度保持不变。环境中视觉色素吸光度和光透射率的比较表明，双视锥细胞的视蛋白互补物对背景光的敏感性最大化，而单视锥细胞的视觉色素在光谱上偏离主要背景波长。我们的结果表明，视蛋白表达的表型可塑性在刺鱼中很小，其功能意义值得怀疑。
Vertebrate colour vision is mediated by the differential expression of visual pigment proteins (opsins) in retinal cone photoreceptors. Many species alter opsin expression during life, either as part of development or as a result of changes in habitat. The latter, a result of phenotypic plasticity, appears common among fishes, but its cellular origin and ecological significance are unknown. Here, we used adult threespine stickleback fish from different photic regimes to investigate heritable variability and phenotypic plasticity in opsin expression. Fish from clear waters had double cones that expressed long (LWS) and middle (RH2) wavelength opsins, one per double cone member. In contrast, fish from red light-shifted lakes had double cones that were >95% LWS/LWS pairs. All fish had single cones that predominantly expressed a short wavelength (SWS2) opsin but ultraviolet cones, expressing a SWS1 opsin, were present throughout the retina. Fish from red light-shifted lakes, when transferred to clear waters, had a similar to 2% increase in RH2/LWS double cones, though double cone density remained constant. Comparison of visual pigment absorbance and light transmission in the environment indicated that the opsin complements of double cones maximized sensitivity to the background light, whereas single cones had visual pigments that were spectrally offset from the dominant background wavelengths. Our results indicate that phenotypic plasticity in opsin expression is minor in sticklebacks and of questionable functional significance.