title: UV-absorbing substance in the red alga Porphyra yezoensis (Bangiales, Rhodophyta) block thymine photodimer production.
abstract: The effect of the water-soluble UV-absorbing substance (UVAS) extracted from the marine red alga Porphyra yezoensis Ueda on UV-dependent thymine photodimer production was investigated. The T<>T pyrimidine-pyrimidone 6-4 dimer and the cyclobutane cis-syn T<>T 5-6 dimer produced by UV irradiation with a xenon lamp were analyzed by reverse-phase high-performance liquid chromatography. Although the dimer production was reduced when the irradiation was filtered through a UVAS solution, it decreased more when thymine was mixed with UVAS. Furthermore, UVAS inhibited the degradation of UV-irradiated thymine. The inhibitory effect of UVAS was significantly greater than that of exogenously added adenine or guanine, which forms complementary base pairs with thymine. These data suggest that in addition to its filtering effect against UV radiation, UVAS also protects thymine by a direct molecule-to-molecule energy transfer process. The protective function of UVAS against UV irradiation is advantageous for this alga under strong UV irradiation.
authors.affiliation: Department of Ecosocial System Engineering, Faculty of Engineering, Yamanashi University, Kofu, Yamanashi 400-8511, Japan, mist@ccn.yamanashi.ac.jp
authors.forename: Taku
authors.initials: T
authors.lastname: Misonou
authors.forename: Junko
authors.initials: J
authors.lastname: Saitoh
authors.forename: Saori
authors.initials: S
authors.lastname: Oshiba
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Tokitomo
authors.forename: Miyuki
authors.initials: M
authors.lastname: Maegawa
authors.forename: Yukio
authors.initials: Y
authors.lastname: Inoue
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Hori
authors.forename: Takeki
authors.initials: T
authors.lastname: Sakurai
mesh_terms: D000042:Absorption; D004249:DNA Damage / Q000187:drug effects; D019281:Dimerization; D010777:Photochemistry; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology* / Q000528:radiation effects; D010940:Plant Proteins / Q000302:isolation & purification / Q000494:pharmacology* / Q000528:radiation effects; D011687:Purines / Q000528:radiation effects; D011740:Pyrimidine Dimers / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D000461:Rhodophyta / Q000737:chemistry* / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D010936:Plant Extracts; D010940:Plant Proteins; D011687:Purines; D011740:Pyrimidine Dimers