الفهرس 
APPROVAL SHEET
Experimental DesignOnly 14 pages are availabe for public view
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Abstract
Ultraviolet radiation (UVR) has negative effects on aquatic organisms. Procambarus clarkii is a freshwater crustacean animal which spread all over the River Nile and its tributaries. It has high ability to tolerate extreme and polluted environments and becomes an important crustacean model organism in research. The present study was designed to evaluate the effects of UV-A irradiation on the intestine (hind gut) and the abdominal muscles of the crayfish Procambarus clarkii using histological, histochemical, electron microscopic studies and some biochemical parameters such as: measurement of the amount of total protein, catalase (CAT) and superoxide dismutase activity (SOD) and X- ray microanalysis on the carapace. To carry out the investigation, specimens were firstly adapted in the Lab, and 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 left for two weeks for recovery after irradiation. 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 exposure of irradiation for 30 min. The damage included intestinal epithelial cells with their membranes, the cuticular layer and the organoids These necrotic effects of UV-A in intestinal cells in irradiated animals may cause lethal lesions. Incomplete recovery was observed in each group after two weeks. In the abdominal skeletal muscle fibers, 15and 30 min. of UV-A irradiation caused obvious damage, lysis of muscle fibers, separation between fibers, infiltration, irregular striations, fragmented fibers and hypertrophied nuclei were observed. The damage increased by increasing the time of UV-A irradiation. After two weeks of recovery, there was incomplete recovery which may need more time for healing process. Electron microscopic study of UV-A irradiated groups for 15and30 minutes confirmed the observations of the light microscopic study where damage of muscle bundles and fibers were observed. The study revealed that the intestine (hind gut) and muscles were highly damaged under short time of exposure to UV-A with the ability to recover after exposures. The muscle tissue treated with UV-A irradiation exhibited marked histopathological changes when compared with untreated muscle tissue. The severity increased with higher dose of UV-A irradiation. The study indicated that the muscles are sensitive tissues affected easily by UV radiation. The study showed a significant decrease in the amount of the total protein after 15 min. of UV-A irradiation compared with the untreated group. After 30 min. of UV-A irradiation a decrease in the total protein was recorded but without a significant difference compared with untreated group. In case of recovered groups, increase of total protein amounts was observed but without significant differences between untreated group and recovered groups. Fifteen min. of UV-A irradiation showed a significance increase of catalase (CAT) activity compared with control group. After 30 min. of UV-A irradiation, non-significant increase of CAT activity compared with control group. In case of recovered groups, there was a non- significant increase in CAT activity compared with the control group but the values were lower than treated groups. There was a significant increase of superoxide dismutase (SOD) activity after 15 min. of UV-A irradiation compared with the control group but there was non-significant increase of SOD activity after 30 min. of UV-A irradiation. Recovered groups showed decrease of SOD activity when compared with treated groups but without a significant difference between recovered groups and control group. Energy dispersive (X- ray) microanalysis of carapace of untreated P. clarkii showed the presence of nine peaks of elements; Al, Si, P, S, Cl, K, Ca, Fe and Zn. Ca had the highest amount level and Fe had the lowest level. After 15 min. and 30 min. of UV-A irradiation, a dramastic change of the different element levels was observed especially for Ca and Fe where Fe had the highest level and Ca had the lowest level.