IMPACT OF UV-A IRRADIATION ON THE INTESTINE OF FRESHWATER CRAYFISH PROCAMBARUS CLARKII.

Procambarus clarkii is a freshwater crustacean which spread all over the River Nile. It has become an important crustacean model organism in research on animal behaviour, environmental stress, toxicity and its economic role. Ultraviolet radiation (UVR) has negative effects on aquatic organisms. The present study was designed to evaluate the effects of UV-A irradiation on the intestine of the crayfish Procambarus clarkii. To carry out the investigation, specimens were firstly adapted in the Lab, then classified into three groups. The first group was chosen as the control (untreated group) and the other two groups were the treated ones. The first treated group was irradiated for 15 minutes of UV-A for two weeks while the second treated group was irradiated for 30 minutes of UV-A for two weeks. Each treated group was lifted for two weeks for recovery after irradiation. After treatments, the intestine including circular and longitudinal muscles were examined. The structural integrity of the epithelium and myoepithelium of the intestine of the control and treated groups were assessed using histological, histochemical and electron microscopic techniques. The significance changes of histological and histochemical were observed in treated animal and discussed. The study revealed that after 15 min. of UV-A irradiation for two weeks, P. clarkii showed signs of damage of intestine and the damage increased with increasing the time of irradiation for 30 min. The damage included intestinal epithelial cells with cell membrane, irregular structure of cuticular layer and absence of organoids seen by electron microscopy. These necrotic effects of UV-A in intestinal cells in irradiated animals may cause lethal lesions. Incomplete recovery was observed in each group.