The sensitivity of Emiliania huxleyi (Prymnesiophycea) to ultraviolet-B radiation

Citation
Agj. Buma et al., The sensitivity of Emiliania huxleyi (Prymnesiophycea) to ultraviolet-B radiation, J PHYCOLOGY, 36(2), 2000, pp. 296-303
Citations number
43
Categorie Soggetti
Aquatic Sciences
Journal title
JOURNAL OF PHYCOLOGY
ISSN journal
00223646 → ACNP
Volume
36
Issue
2
Year of publication
2000
Pages
296 - 303
Database
ISI
SICI code
0022-3646(200004)36:2<296:TSOEH(>2.0.ZU;2-O
Abstract
Emiliania huxleyi (Lohm.) Hay et Miller is an important component of the ph ytoplankton in open ocean waters. The sensitivity of this cosmopolitan alga to natural levels of UVB radiation has never been tested. Since DNA is bel ieved to be a major target of natural UVB radiation (UVBR: 280-315 nm) in l iving cells, experiments with E. huxleyi were performed using growth rate r eduction and DNA damage as indicators of UVBR stress. Specific growth rate, cell volume, pigment content, and CPD (cyclobutane pyrimidine dimer) forma tion (a measure for DNA damage) were followed during and after prolonged ex posure of a series of cultures to a range of UVBR levels. E. huxleyi was fo und to be very sensitive to UVBR: at a daily weighted UVBR dose of only 400 J.m(-2).d(-1) (BEDDNA300nm), growth was halted. At this UVBR level, both c ell volume and contents of the major photosynthetic and photoprotective pig pigments had increased. The UVBR vulnerability of huxleyi cannot be explai ned by a high potential for cyclobutane thymine dimer formation (the most a bundant CPD type) due to a high T content of nuclear DNA: the CG content of this E huxleyi strain is high (68%) compared with other species. The high UVBR sensitivity may be related to the stage of the cell cycle during UVBR exposure, in combination with low repair capacity, It is concluded that E. huxleyi may experience UVBR stress through the formation of cyclobutane pyr imidine dimers, with subsequent low repair capacity and thereby arrest of t he cell cycle.