Carotenoid accumulation in copepods is related to lipid metabolism and reproduction rather than to UV‐protection
Carotenoid accumulation in copepods is related to lipid metabolism and reproduction rather than to UV‐protection
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桡足类中类胡萝卜素的积累与脂质代谢和繁殖有关，而不是与紫外线防护有关
DOI：
10.1002/lno.10283
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发表时间：
2016
影响因子：
4.5
通讯作者：
M. Rautio
中科院分区：
文献类型：
--
作者：
T. Schneider;Guillaume Grosbois;W. Vincent;M. Rautio
类胡萝卜素色素在桡足类中的积累通常被描述为一种塑料适应，提供了对紫外线辐射（UVR）的光保护。然而，季节性类胡萝卜素最大值的报告，在冬季，当紫外线辐射低，挑战建议的驱动作用紫外线辐射。因此，我们在这里评估紫外线辐射和桡足类胡萝卜素色素沉着的季节性模式之间的机械连接。我们评估了类胡萝卜素，脂肪酸含量和繁殖的Leptodiaptomus minutus沿着与紫外线照射，水温，浮游植物色素，鱼类捕食在北方湖泊在18个月，覆盖两个冬季。主要的类胡萝卜素虾青素以游离形式存在，以及与脂肪酸酯化。单酯和二酯占总虾青素的62-93%，并随季节变化与脂肪酸密切相关。桡足类总虾青素含量的季节性变化特征是晚秋的净积累量高达0.034 μg（mg干质量）−1 d−1，导致冬季中期的最大值为3.89 ± 0.31 μg mg−1。两个净损失期（-0.018 μg mg−1 d−1和-0.021 μg mg−1 d−1）与春季和夏季的产蛋高峰相吻合，导致秋季的虾青素含量最低（0.86 ± 0.03 μg mg−1）。这一时期的特点也是最高的捕食压力由年轻的一年的鱼。结果表明，虾青素在桡足类中的积累与脂质代谢密切相关，但与UVR-光保护无关，脂肪酸和类胡萝卜素的季节变化与生殖周期有关。
Accumulation of carotenoid pigments in copepods has often been described as a plastic adaptation providing photoprotection against ultraviolet radiation (UVR). However, reports of seasonal carotenoid maxima in winter, when UVR is low, challenge the proposed driving role of UVR. Therefore, we here evaluate the mechanistic connection between UVR and the seasonal pattern of copepod carotenoid pigmentation. We assessed the carotenoids, fatty acid content and reproduction of Leptodiaptomus minutus along with UVR exposure, water temperature, phytoplankton pigments, and fish predation in a boreal lake during 18 months covering two winter seasons. The predominant carotenoid astaxanthin occurred in free form as well as esterified with fatty acids. Mono‐ and diesters accounted for 62–93% of total astaxanthin and varied seasonally in close correlation with fatty acids. The seasonal variability in total astaxanthin content of the copepods was characterized by net accumulation in late fall of up to 0.034 μg (mg dry mass)−1 d−1, which led to the mid‐winter maximum of 3.89 ± 0.31 μg mg−1. The two periods of net loss (−0.018 μg mg−1 d−1 and −0.021 μg mg−1 d−1) coincided with peaks of egg production in spring and summer leading to minimum astaxanthin content (0.86 ± 0.03 μg mg−1) in fall. This period was also characterized by the highest predation pressure by young‐of‐the‐year fish. The results suggest that accumulation of astaxanthin in copepods is strongly related to lipid metabolism but not to UVR‐photoprotection, and that seasonal changes of fatty acids and carotenoids are related to the reproduction cycle.