Avian retinal oil droplets: dietary manipulation of colour vision?
Avian retinal oil droplets: dietary manipulation of colour vision?
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DOI：
10.1098/rspb.2009.1805
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发表时间：
2010-03-22
影响因子：
4.7
通讯作者：
Bennett, Andrew T. D.
中科院分区：
文献类型：
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作者：
Knott, Ben;Berg, Mathew L.;Bennett, Andrew T. D.
鸟类的视觉是高度发达的，鸟类的视网膜含有杆状和双视锥感光器，以及四种类型的单视锥，以满足四色色视觉。视锥细胞含有一个富含类胡萝卜素色素的油滴(VS/紫外线敏感视锥细胞除外)，它起到了滤光器的作用，实质上改变了光感受器检测到的光。通过饮食控制，我们测试了类胡萝卜素对两个物种油滴吸收特性的影响：秀丽鸭嘴兽和点滴带绦虫。使用显微分光光度法，我们确定了操作是否会影响油滴类胡萝卜素的浓度，以及改变是否会改变颜色识别能力。在这两个物种中，类胡萝卜素浓度在添加类胡萝卜素的鸟类中都有增加，但只在双锥体中出现。手法作用的大小通常取决于视网膜的位置。据我们所知，这项研究首次提供了饮食摄入量在短时间内影响视网膜油滴中类胡萝卜素浓度的实验证据。此外，这两个物种对视网膜的类胡萝卜素分配是这样的，这种变化潜在地保留了色觉的光谱调谐。我们的研究为视网膜对油滴类胡萝卜素浓度的调节提供了新的见解，这是一个知之甚少的领域，对于我们理解鸟类类胡萝卜素分配中的权衡具有重要意义。
Avian vision is highly developed, with bird retinas containing rod and double-cone photoreceptors, plus four classes of single cones subserving tetrachromatic colour vision. Cones contain an oil droplet, rich in carotenoid pigments (except VS/ultraviolet-sensitive cones), that acts as a filter, substantially modifying light detected by the photoreceptor. Using dietary manipulations, we tested the effects of carotenoid availability on oil droplet absorbance properties in two species: Platycercus elegans and Taeniopygia guttata. Using microspectrophotometry, we determined whether manipulations affected oil droplet carotenoid concentration and whether changes would alter colour discrimination ability. In both species, increases in carotenoid concentration were found in carotenoid-supplemented birds, but only in the double cones. Magnitudes of effects of manipulations were often dependent on retinal location. The study provides, to our knowledge, the first experimental evidence of dietary intake over a short time period affecting carotenoid concentration of retinal oil droplets. Moreover, the allocation of carotenoids to the retina by both species is such that the change potentially preserves the spectral tuning of colour vision. Our study generates new insights into retinal regulation of carotenoid concentration of oil droplets, an area about which very little is known, with implications for our understanding of trade-offs in carotenoid allocation in birds.