Effects of UV radiation on the rice field cyanobacterium, Aulosira fertilissima

The effects of UV radiation (5 W m(-2)) were studied in the cyanobacterium, Aulosira fertilissima. The organism was found to be sensitive to UV-B and, to a lesser extent, UV-A. Absorption spectra showed that the pigment content, particularly phycocyanin, severely decreased following UV exposures; the effect was more pronounced with UV-B than with W-A. The organism was also very sensitive to solar radiation, and complete bleaching of the cells occurred following exposure of 2-3 hr. Tbe absorption and fluorescence emission spectra of crude pigments after 3 hr of W-B exposure (5 W m(-2)) decreased significantly, suggesting the loss of effective energy transfer from the accessory pigments to PS-IT. SDS-PAGE analysis of the total protein profile of cells treated with W-E showed a decrease in the protein content with increasing exposure time. Substantial decrease in the protein bands occurred after 3 hr of UV-B exposure (5 W m(-2)), particularly of those between 14.2 and 45 kDa.