Effect of UV-B radiation on the marine diatoms Lauderia annulata and Thalassiorsira rotula grown in different salinities |
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Authors: | G. Döhler |
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Affiliation: | (1) Botanisches Institut der Johann Wolfgang Goethe-Universität, Frankfurt am Main; Siesmayerstraße 70, D-6000 Frankfurt am Main 11, Federal Republic of Germany |
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Abstract: | The marine diatoms Lauderia annulata Cleve and Thalassiosira rotula Meunier were grown at different salinities (20, 35 and 45) and exposed to different levels of midultraviolet, UV-B) 439, 717 and 1230 J m-2 d-1, weighted) for 2 d. A low UV-B dose (439 J m-2 d-1) usually caused a slight increase in biomass production (dry weight) compared to non-UV-B irradiated cells. Enhanced UV-B radiation (717 J m-2 d-1) depressed protein and pigment content (chlorophyll a, chlorophyll c1+c2 and carotenoids), especially in algae grown at 20 or 35 salt concentration of the nutrient solution. The effect of UV-B radiation (717 J m-2 d-1) on the pattern and concentration of amino acids was species-dependent. Aspartic acid was reduced in all tested diatoms. A drastic increase in glutamine and a reduction in glutamic acid pools could be observed in L. annulata samples, but no significant variation of the impact of UV-B was found in dependence on the salt concentration of the nutrient medium. T. rotula cells grown at 35 S showed an increase of glutamic acid and a decrease of glutamine levels after UV-B radiation. The results are discussed in relation to the impact of UV-B upon carbon and nitrogen metabolism. |
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