Kwan-Ha Park

The effect of mistletoe, Viscum album coloratum, extract on innate immune response of Nile tilapia (Oreochromis niloticus).

The purpose of the present study was to evaluate the effect of dietary mistletoe extracts on non-specific immune response and disease resistance of Nile tilapia (Oreochromis niloticus) against Aeromonas hydrophila infection. Tilapia fingerlings were fed with a diet containing 0 mg as a control, 10 mg, 50 mg, and 200 mg mistletoe powder kg(-1) dry diet for 80 days. The immunological parameters, respiratory burst activity, lysozyme activity, alternative complement haemolysis activity (ACH(50)), and phagocytic activity of fish were investigated following 20, 40 and 80 days of feeding. Fish were challenged with A. hydrophila on 80 days after feeding and mortalities were checked over 10 days post-infection. The results show that fish fed with mistletoe extract exhibited an increase in activity in all immunological parameters (P < 0.05) compared to the control group depending on feeding periods and doses of mistletoe. Following challenge with A. hydrophila, 42% less survivability was observed in the control group than in other experimental diet groups. The highest survival rate (83%) was shown in the group fed with a 50 mg mistletoe kg(-1) diet. The results suggest that mistletoe enables tilapia to promote immunity and be more resistant to A. hydrophila infection.

Effect of Levamisole on Enhancing Natural Cytotoxic Cell Activity in Nile Tilapia Oreochromis niloticus

The study examined the effect of levamisole on the natural cytotoxic cell (NCC) activity of Nile tilapia (Oreochromis niloticus) head kidney (HK) leukocytes. In vitro, HK leukocytes were incubated with to ng of levamisole/ml for 5, 20 or 40 h and then their NCC activity against target cells was assayed. The NCC activity appeared to increase after a 20 h of incubation. In vivo, tilapia were fed commercial diet containing 0, 50, 100 or 300 mg of levamisole/kg for 12 consecutive days. Then, the fish were fed a commercial normal diet and samples harvested weekly 0 to 8 weeks after levamisole administration. The NCC activity was augmented uniformly at all times examined until the end of the experiment. In conclusion, levamisole effectively enhanced and maintained tilapia NCC activity.

The Proliferative and Apoptotic Properties of Nile Tilapia (Oreochromis niloticus) sIg + Lymphocytes by Cortisol Treatment

The effects of cortisol on proliferation and apoptosis of tilapia surface immunoglobulin positive (sIg + ) lymphocytes isolated from different tissues were investigated. sIg + lymphocytes from the tilapia head kidney (HK) and spleen showed a higher proliferation and lower intracellular calcium (Ca 2+ i) level to Ig-crosslinking compared with peripheral blood sIg + lymphocytes. Peripheral blood sIg + lymphocytes stimulated with lipopolysaccharide (LPS) showed high levels of apoptosis in the presence of cortisol. HK and to a lesser extent spleen sIg + lymphocytes, although less sensitive than their equivalent in peripheral blood, showed cortisol-induced apoptosis irrespective of LPS stimulation of control levels. Compared to plasma values measured during stress conditions, proliferation regardless of LPS stimulation was apparently suppressed by cortisol that is effective in inducing a significant increase in apoptosis in all three different cell populations of sIg + cells, suggesting the immunoregulatory effect of cortisol in both LPS stimulated and non-stimulated conditions. Different sensitivity of sIg + cells to the cortisol, in regard to developmental stage and + lymphocytes. + lymphocytes, Cortisol, Apoptosis, Proliferation)