title: Phlorotannin production and lipid oxidation as a potential protective function against high photosynthetically active and UV radiation in gametophytes of Alaria esculenta (Alariales, Phaeophyceae).
abstract: Radiation damage can inter alia result in lipid peroxidation of macroalgal cell membranes. To prevent photo-oxidation within the cells, photoprotective substances such as phlorotannins are synthesized. In the present study, changes in total fatty acids (FA), FA composition and intra/extracellular phlorotannin contents were determined by gas chromatography and the Folin-Ciocalteu method to investigate the photoprotective potential of phlorotannins to prevent lipid peroxidation. Alaria esculenta juveniles (Phaeophyceae) were exposed over 20 days to high/low photosynthetically active radiation (PAR) in combination with UV radiation (UVR) in the treatments: PAB (low/high PAR + UV-B + UV-A), PA (low/high PAR + UV-A) or low/high PAR only. While extracellular phlorotannins increased after 10 days, intracellular phlorotannins increased with exposure time and PA and decreased under PAB. Interactive effects of time:radiation wavebands, time:PAR dose as well as radiation wavebands:PAR dose were observed. Low FA contents were detected in the PA and PAB treatments; interactive effects were observed between time:high PAR and PAB:high PAR. Total FA contents were correlated to extra/intracellular phlorotannin contents. Our results suggest that phlorotannins might play a role in intra/extracellular protection by absorption and oxidation processes. Changes in FA content/composition upon UVR and high PAR might be considered as an adaptive mechanism of the A. esculenta juveniles subjected to variations in solar irradiance.
authors.affiliation: Department of Marine Botany, University of Bremen, Bremen, Germany. Franciska.Steinhoff@ntnu.no
authors.forename: Franciska S
authors.initials: FS
authors.lastname: Steinhoff
authors.forename: Martin
authors.initials: M
authors.lastname: Graeve
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Bartoszek
authors.forename: Kai
authors.initials: K
authors.lastname: Bischof
authors.forename: Christian
authors.initials: C
authors.lastname: Wiencke
mesh_terms: D008055:Lipids / Q000737:chemistry*; D010084:Oxidation-Reduction; D000459:Phaeophyceae / Q000737:chemistry / Q000528:radiation effects*; D010788:Photosynthesis; D013634:Tannins / Q000138:chemical synthesis*; D014466:Ultraviolet Rays
chemical_list: D008055:Lipids; D013634:Tannins