title: UV radiation-induced accumulation of photoprotective compounds in the green alga Tetraspora sp. CU2551.
abstract: The effect of UV radiation on the accumulation of novel mycosporine-like amino acids (MAAs) along with their photoprotective function was investigated in the green alga Tetraspora sp. CU2551. No UV-absorbing compound was detected in this organism growing under normal light condition while two MAAs with absorption maxima at 324 nm and 322 nm were found to be accumulated after UV irradiation. The effects of UV exposure time with different cut-off filter foils namely 295 (PAR + UV-A + UV-B), 320 (PAR + UV-A) and 395 nm (PAR only) were studied on induction of the synthesis of these MAAs. Concentration of MAAs was found to increase with increase in exposure time under UV radiation. Furthermore, the antioxidant and photoprotective action of these MAAs was also investigated. The role of MAAs in diminishing the UV-induced production of ROS in vivo was also demonstrated using the oxidant-sensing probe 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) and results obtained supported the results of DPPH free radical scavenging assay. The MAAs also exhibited efficient photoprotective ability on Escherichia coli cells against UV-B stress. Thus, the MAAs in Tetraspora sp. CU2551 may act as efficient antioxidants as well as UV-sunscreen. This is the first report for the UV-induced synthesis and co-accumulation of these MAAs and their photoprotective actions in Tetraspora sp. which is a member of the class Chlorophyceae. Moreover, UV-induced accumulation as well as photoprotective function of these compounds may facilitate this chlorophyte to perform important ecological functions in harsh environmental conditions with high UV-B fluxes in their brightly lit habitats.
authors.affiliation: Laboratory of Cyanobacterial Biotechnology, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Rajesh P
authors.initials: RP
authors.lastname: Rastogi
authors.forename: Aran
authors.initials: A
authors.lastname: Incharoensakdi
mesh_terms: D000222:Adaptation, Physiological; D000596:Amino Acids / Q000096:biosynthesis / Q000378:metabolism* / Q000494:pharmacology; D000975:Antioxidants; D001713:Biphenyl Compounds / Q000378:metabolism; D000460:Chlorophyta / Q000378:metabolism* / Q000528:radiation effects; D017753:Ecosystem; D004926:Escherichia coli / Q000187:drug effects / Q000528:radiation effects; D005452:Fluoresceins / Q000378:metabolism; D010851:Picrates / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013312:Stress, Physiological; D014466:Ultraviolet Rays
chemical_list: C110400:2',7'-dichlorodihydrofluorescein diacetate; D000596:Amino Acids; D000975:Antioxidants; D001713:Biphenyl Compounds; D005452:Fluoresceins; D010851:Picrates; D017382:Reactive Oxygen Species; C004931:1,1-diphenyl-2-picrylhydrazyl
keywords: Antioxidants; Mycosporine-like amino acids; Photoprotection; Reactive oxygen species; Tetraspora sp.; UV radiation