Dietary acquisition of photoprotective compounds (mycosporine-like amino acids, carotenoids) and acclimation to ultraviolet radiation in a freshwater copepod
Dietary acquisition of photoprotective compounds (mycosporine-like amino acids, carotenoids) and acclimation to ultraviolet radiation in a freshwater copepod
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DOI：
10.4319/lo.2005.50.2.0427
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发表时间：
2005-03-01
影响因子：
4.5
通讯作者：
Sommaruga, R
中科院分区：
文献类型：
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作者：
Moeller, RE;Gilroy, S;Sommaruga, R
我们通过实验检验了这样的假设：类胡萝卜素或吸收紫外线的菌孢素样氨基酸 (MAAS) 等膳食化合物的积累可以防止自然水平的紫外线辐射 (UVR)。一种桡足类桡足类动物 Leptodiaptomus minutus 是从宾夕法尼亚州一个相对紫外线透明的湖泊中采集的，该湖中桡足类 MAAS 和类胡萝卜素的水平在一年中有所不同（夏季 MAAS 高/类胡萝卜素低）。在实验室中经不同饮食/紫外线处理饲养的动物会从产生 MAA 的甲藻中积累 MAAS，但不会从缺乏 MAA 的隐藻中积累 MAAS。在暴露于补充 UVR 的光合活性辐射（PAR，400-700 nm）下，采集效率有所提高，MAA 浓度高达干重的 0.7%，而未补充 PAR 的情况下，MAA 浓度仅为 0.3%。动物及其饮食之间的个体 MAAS 比例有所不同。较短波长的吸收性 plythine 和 shinorine（λ（最大值）分别为 320 和 334 nm）在 usujirene 和 plythene（λ（最大值）约 359 nm）上不成比例地积累。当膳食 MAAS 不可用时，类胡萝卜素在 UVR 照射下积累（至 1% 干重）。在人工 UV-B 辐射急性暴露 12 小时后，对紫外线 B (UV-B) 辐射的耐受性评估为 LE(50)s（紫外线暴露 5 天后死亡率为 50%）。对于适应紫外线、富含 MAA 的动物，LE,os 增加了 2.5 倍，但对于适应紫外线、富含类胡萝卜素的动物，LE,os 仅增加 1.5 倍。与类胡萝卜素相比，MAAS 为桡足类动物提供了更有效的光保护策略，可能与 DNA 损伤的光修复一样重要，以提高对自然水平 UV-B 辐射的耐受性。
We experimentally tested the hypothesis that accumulations of dietary compounds such as carotenoids or UV-absorbing mycosporine-like amino acids (MAAS) protect against natural levels of ultraviolet radiation (UVR). A calanoid copepod, Leptodiaptomus minutus, was collected from a relatively UV-transparent lake in Pennsylvania where levels of copepod MAAS and carotenoids vary during the year (MAAS high/carotenoids low in summer). Animals raised in the laboratory under different diet/UVR treatments accumulated MAAS from an MAA-producing dinoflagellate but not from a cryptomonad that lacks them. The acquisition efficiency increased under exposure to UVR-supplemented photosynthetically active radiation (PAR, 400-700 nm), yielding MAA concentrations up to 0.7% dry weight compared with only 0.3% under unsupplemented PAR. Proportions of individual MAAS differed between the animals and their diet. Shorter wavelength absorbing palythine and shinorine (lambda(max) 320 and 334 run, respectively) were disproportionately accumulated over usujirene and palythene (lambda(max) ca. 359 nm). Carotenoids accumulated under UVR exposure (to 1% dry weight) when dietary MAAS were not available. Tolerance of ultra-violet-B (UV-B) radiation was assessed as LE(50)s (UV exposure giving 50% mortality after 5 d) following 12-h acute exposure to artificial UV-B radiation. LE,os increased 2.5-fold for UV-acclimated, MAA-rich animals, but only 1.5-fold for UV-acclimated, carotenoid-rich animals. Compared with carotenoids, MAAS offer this copepod a more effective photoprotection strategy, potentially as important as photorepair of DNA damage, to promote tolerance of natural levels of UV-B radiation.