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Oxidative stress and antioxidant content in Chlorella vulgaris after exposure to ultraviolet‐B radiation
Author(s) -
Malanga Gabriela,
Puntarulo Susana
Publication year - 1995
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1995.tb00983.x
Subject(s) - catalase , superoxide dismutase , antioxidant , lipid peroxidation , oxidative stress , chlorella vulgaris , biochemistry , chemistry , food science , reactive oxygen species , biology , botany , algae
Growth of Chlorella vulgaris was measured in cultures irradiated with 0, 0.8, 2.0 and 4.4 kJ m 2 UV‐B. Growth expressed as chlorophyll content, declined significantly with increased UV‐B dose. Ultraviolet‐B irradiated cultures in log phase of growth showed a 284% increase in oxygen radical generation and a 145% increase in lipid peroxidation compared with unirradiated cultures, whereas cultures in the stationary growth phase showed no significant changes in these parameters. The activities of superoxide dismutase and catalase increased by 40 and 500%, respectively, after exposure to a UV‐B dose of 4.4 kJ m −2 . Contents of the lipophilic antioxidants α‐tocopherol and β‐carotene increased by 180 and 63 amol cell −1 respectively, between log and stationary phases in unirradiated cultures; but in UV‐B‐irradiated cultures these increases were significantly depressed. Photoreducing capacities of chloroplasts were decreased following UV‐B irradiation of both isolated chloroplasts and those isolated from irradiated algae. Cells exposed to UV‐B exhibited increased size and starch accumulation. These results suggest that oxidative stress conditions related to UV‐B exposure trigger an antioxidant response that includes an increase in the activity of the antioxidant enzymes (superoxide dismutase and catalase).