Acclimation of Anabas testudineus (Bloch) to three test temperatures influences thermal tolerance and oxygen consumption.

Teleost fish have developed their own specific adaptive mechanism, both behavioral and physiological, to maintain homeostasis in response to unfavorable temperatures. Therefore, this study was aimed at assessing the critical thermal maxima (CT(Max)), critical thermal minima (CT(Min)), and oxygen consumption rate of Anabas testudineus (17.03 +/- 1.2 g) after acclimating to three preset temperatures (25, 30, and 35 degrees C) for 30 days. The CT(Max) and CT(Min) were 40.15, 41.40, 41.88 degrees C and 12.43, 13.06, 13.94 degrees C, respectively, and were significantly different (P < 0.05). The thermal tolerance polygon for the specified temperatures was 278.30 degrees C(2). The oxygen consumption rate (117.03, 125.70, 198.48 mg O(2) kg(-1) h(-1), respectively) increased significantly (P < 0.05) with increasing acclimation temperatures. The overall results indicate that the thermal tolerance and oxygen consumption of A. testudineus are dependent on acclimation.

Biochemical and stress responses of rohu Labeo rohita and mrigal Cirrhinus mrigala in relation to acclimation temperatures.

The biochemical and stress responses of two Indian major carps, rohu Labeo rohita and mrigal Cirrhinus mrigala were studied after acclimating them to four preset temperatures (26, 31, 33 and 36 degrees C) for 30 days. The blood glucose and liver glycogen levels showed an inverse trend in both the species and were significantly different in L. rohita at higher temperatures. The decrease in the liver glycogen level of C. mrigala, however, was not significant. Plasma cortisol levels increased significantly whereas the ascorbic acid content in the brain and kidney of both the species decreased significantly with increasing temperatures. Total lipid content in the liver of both the species decreased significantly with increasing acclimation temperatures. The phospholipid concentration decreased in L. rohita with increasing acclimation temperatures, and in C. mrigala the values decreased up to 33 degrees C and increased at 36 degrees C. In C. mrigala, the cholesterol level decreased up to 33 degrees C and then increased at 36 degrees C, but the absolute value was lower in comparison to L. rohita. The cholesterol levels, however, were not significantly different in L. rohita. Triglycerides and free fatty acids concentrations decreased significantly with increasing acclimation temperatures in both the species. The present study indicates species-specific metabolic responses of L. rohita and C. mrigala to thermal acclimation.

Persistent sub-lethal chlorine exposure augments temperature induced immunosuppression in Cyprinus carpio advanced fingerlings.

Apart from increased temperature, thermal effluents discharged through cooling systems of nuclear power plants may often contain chlorine (used against bio-fouling), which may affect the immune status of fish. Therefore, a 28-day trial was undertaken to delineate the effect of high temperature and a persistent sub-lethal chlorine exposure on immunomodulation in Cyprinus carpio advanced fingerlings. Fish were acclimated to four different temperatures (26, 31, 33 and 36 degrees C) and maintained for 30 days in two different groups. One group was exposed to persistent chlorine (0.1mgL(-1)) and was compared with their respective temperature control groups (without chlorine exposure). Expression of heat shock proteins (hsp 70) was tested in muscle after 28 days using Western blotting. Haematological parameters (erythrocyte count, leucocyte count, haemoglobin), serum parameters (total protein, albumin, globulin, A/G ratio) and respiratory burst activity were tested to assess immuno-competence of C. carpio in response to temperature and chlorine exposure. Results indicated that hsp 70 was induced at 36 degrees C in temperature control groups but not in their respective temperatures in the presence of chlorine. Haematological parameters such as haemoglobin, erythrocyte and leucocyte counts appeared depressed in chlorine treated groups as compared to their respective temperature control groups. Serum protein and globulin were affected due to chlorine exposure at different acclimation temperatures. A decrease in NBT activity was recorded in chlorine treated groups as compared to their respective temperature control groups. Overall results indicate that increasing acclimation temperatures alters the immune status of C. carpio advanced fingerlings and persistent sub-lethal exposure to chlorine augments this temperature induced immunosuppression.

Dietary high protein and vitamin C mitigate stress due to chelate claw ablation in Macrobrachium rosenbergii males.

Stress due to claw ablation was tested in Macrobrachium rosenbergii males. Dietary high protein and vitamin C were supplemented for amelioration of stress. We used four different treatments: fed with 25% protein and a normal dose (0.12%) of vitamin C (T(1)); 35% protein and a normal dose (0.12%) of vitamin C (T(2)); 25% protein and a high dose (0.24%) of vitamin C (T(3)); and high protein 35% and a high dose (0.24%) of vitamin C (T(4)) for 30 days. All test prawns (T(1) to T(4)) were subjected to ablation of their second chelate legs after the 15th day of the feeding trial. A control treatment was maintained without claw ablation and fed with 25% protein. Haemolymph glucose, hepatopancreatic glycogen, muscle ascorbate and enzyme activities (glucose 6 phosphatase (G6Pase), fructose-1,6-bisphosphatase (FBPase), lactate dehydrogenase (LDH), Alanine aminotransferase (ALT) in hepatopancreas) were tested at different recovery periods (0, 6, 24 h, 7 and 14 days). Results indicate a high glucose level immediately after claw ablation and a concomitant increase in gluconeogenic enzymes (G6Pase and FBPase). However, glycogen reserves were regained in the treatments due to claw ablation stress after 24 h. LDH and ALT activity decreased in the hepatopancreas of M. rosenbergii up to 24 h after claw ablation. Overall results indicate that claw ablation is stressful to M. rosenbergii and high protein and vitamin C diet may mitigate stress due to claw ablation.