Sonntag Bettina, Kammerlander Barbara, Summerer Monika
University of Innsbruck, Institute of Ecology, Innsbruck, Austria.
University of Innsbruck, Research Institute for Limnology, Mondsee, Austria.
Inland Waters. 2017 Jan 2;7(1):55-64. doi: 10.1080/20442041.2017.1294348. Epub 2017 May 2.
Ciliates in shallow alpine lakes are exposed to high levels of incident solar ultraviolet radiation (UVR). We observed the presence of specific sunscreen compounds, the mycosporine-like amino acids (MAAs), in several populations of , a relatively large ciliate species found in such lakes. The populations from 3 highly UV transparent lakes revealed the presence of 7 MAAs (MG, SH, PR, PI, AS, US, and PE) in total concentrations of 3.6-52.4 10 μg μg dry weight (DW) per individual, whereas in one glacially turbid and less UV transparent lake, no MAAs were detected in the population. The MAAs in the ciliates generally reflected the composition and relative amounts of the lakes' seston MAAs, assuming that the ciliates fed on MAA-rich plankton. We experimentally found that naturally acquired MAAs prevented ciliate mortality under simulated UVR and photosynthetically active radiation (PAR) conditions. We further tested the dietary regulation of the MAAs-content in the ciliates under artificial UVR and PAR exposure and found an increase in MAAs concentrations in all treatments. Our assumption was that several stress factors other than irradiation were involved in the synthesis or up-regulation of MAAs.
高山浅水湖泊中的纤毛虫会受到高强度的太阳紫外线辐射（UVR）。我们在几种 的种群中观察到了特定的防晒化合物，即类菌孢素氨基酸（MAAs）， 是在这类湖泊中发现的一种相对较大的纤毛虫物种。来自3个紫外线透明度高的湖泊的种群总共含有7种MAAs（MG、SH、PR、PI、AS、US和PE），个体干重（DW）中MAAs的总浓度为3.6 - 52.4 μg/μg，而在一个冰川浑浊且紫外线透明度较低的湖泊中，在 种群中未检测到MAAs。假设纤毛虫以富含MAAs的浮游生物为食，纤毛虫体内的MAAs通常反映了湖泊悬浮有机物中MAAs的组成和相对含量。我们通过实验发现，自然获得的MAAs在模拟紫外线辐射（UVR）和光合有效辐射（PAR）条件下可防止纤毛虫死亡。我们进一步测试了在人工紫外线辐射（UVR）和光合有效辐射（PAR）暴露下纤毛虫体内MAAs含量的饮食调节，发现在所有处理中MAAs浓度均有所增加。我们的假设是，除辐射外的其他几个应激因素参与了MAAs的合成或上调。
