ABSTRACT
On a global scale, stratospheric ozone depletion has caused an increase in UV-B radiation reaching the earth's surface. Ultraviolet radiation has long been suspected to be harmful to aquatic organisms. In order to study ionocyte localization [by Na[+]/K[+]-ATPase immunolocalization] and the effects of UV radiation on the ionocytes of skin and gills, the alevins of Salmo trutta caspius were exposed to different doses of UV radiation [unit low doses [ULD] of: 60 microw/cm[2] [JVC; 100 microw/cm[2] UVB and 40 microw/cm[2] UVA and unit high doses [UHD] of: 90 microw/cm[2] UVC; 130 microw/cm[2] UVB and 50 microw/cm[2] UVA] using two adjustable F8T5 UV-B, 302 nm lamps [Japan] for 15 minutes once a day in laboratory conditions. Afevins not subjected to UV exposure served as a control group. In both UV exposure groups, all the alevins died on the ninth day. No mortality was observed in the control group. The Na[+]/k[+]-ATPase immunolocalization study indicated that ionocytes were located, in lessening order, on the yolk sac, trunk, gills, opercula and rarely on the head skin. Immunohistochemical results showed significant reduction in the number of ionocytes on the yolk sac; with lesser reduction on the trunk in both UV exposure groups. In contrast, the number of immunoffuorescence cells on the gill was significantly elevated. Our results also showed that the size of ionocytes was reduced on the trunk and yolk sac in the UV exposure groups, but not significantly. Deformation and destruction of ionocytes on the yolk sac and trunk were observed with scanning electron microscope [SEM] in the UV exposure groups. Our results showed that ionocytes were located mainly on the yolk sac, in lesser amounts on the trunk, gills and opercula, and rarely also on the head skin of alevins. UV radiation caused deformation and reduction in the number and size of ionocytes on the trunk and yolk sac. As the skin cells of trout alevins possess essential functions for respiration, osmoregulation, excretion and defense during this stage of life, the observed damage may have contributed to their suddenly mortality in the UV exposure condition
Subject(s)
Animals , Ultraviolet Rays , Gills , Skin/radiation effectsABSTRACT
Changes in chloride cell abundance, Na+, K+-ATPase immunolocalization and activity were investigated in the gills of the golden grey mullet, Liza aurata, fry acclimated to freshwater [FW] and different salinities [12', 36' and 46%]. Na+, K+-ATPase localization was performed through immunofluorescence light microscopy using a mouse monoclonal antibody IgG alpha 5. Quantitive analysis of Na+, K+-ATPase intensity was analyzed using Optima's version 6.51 image analysis software [Media Cybernetics, Silver Spring, MD, USA]. In FW, the fluorescent cells [chloride cells] were observed on the epithelia of filaments [mainly in inter-lamellar regions] and on the lamellae. Following transfer to 12%. salinity, the abundance of Na+, K+-ATPase immunofluorescence cells on the filaments decreased 1.7-fold, and no immunofluorescence cells were detected on the lamellae. Samples from 36% and 46%. salinity showed a high density of chloride cells on the epithelia of filaments, and a few cells on the lamellae. Na+, K+-ATPase intensity did not change significantly with an increase in salinity from 36% to 46% but it was significantly higher [p > 0.05] in the FW compared to 12% salinity. There was no significant difference between gill Na+, K+-ATPase activity in FW and 12% salinity, but it was significantly higher [p > 0.05] in the fish acclimated to 36' and 46% salinity [3.3- and 5.1-fold] compared to 12%. The capability of L. aurata fry to change the number and size of gill chloride cells, as well as their activities indicate the high degree of adaptability of this fish to a wide range of salinity