Impact of UV-B radiation on antioxidant enzymes and protein electrophoretic pattern of the green algaChlorococcum sp.

The impact of two intensities (2.5 and 5 W m−2) of ultraviolet-B (UV-B) radiation on lipid peroxidation, protein pattern and some antioxidant enzymes including superoxide dismutase, catalase and peroxidase has been studied inChlorococcum sp. isolated from El-Kased freshwater canal, Tanta, Egypt. Exposure ofChlorococcum sp. for 2 h to 2.5 and 5 W m−2 increased malondialdehyde (MDA) content by 238 and 274%, respectively. The activity of superoxide dismutase and peroxidase were increased at all exposure times at both intensities. In contrast, the activity of catalase was inhibited by increasing UV-B intensity as well as exposure time compared to the control. The reduction in catalase activity reached 71.8 and 95.9% after 2 h of exposure to 2.5 and 5 W m−2, respectively. With regard to protein pattern, exposure ofChlorococcum sp. to UV-B stress induced marked changes in protein synthesis patterns. Three types of alterations were noticed, i) significant reduction in the biosynthesis of certain proteins, ii) induction of specific proteins biosynthesis and iii) changes in band intensities of some proteins.