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Rejitha, V.
- Short-Term Salinity Acclimation Demands Thyroid Hormone Action in the Climbing Perch Anabas testudineus Bloch
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Authors
Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram 695581, Kerala, IN
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram 695581, Kerala, IN
Source
Journal of Endocrinology and Reproduction, Vol 13, No 2 (2009), Pagination: 63-72Abstract
Fishes have developed many complex physiological mechanisms to combat osmotic challenges. In this study triiodothyronine (T3), thyroxine (T4) and cortisol in the plasma were quantified and the indices of metabolic and hydromineral regulations analyzed in the climbing perch Anabas testudineus after exposing the fish to a selected salinity (20 ppt) for varied intervals (1, 7, 14 and 21 days) to study the physiological basis of short- and long-term salinity acclimation. It was found that transfer of fish to 20 ppt salinity for a day after transient salinity changes, plasma T4 was elevated, and plasma T3 decreased whereas plasma cortisol remained unchanged. The levels of these hormones, however, returned to basal levels when these fish were kept for a prolonged acclimation of three weeks. Plasma glucose and lactate showed no change in response to salinity acclimation, whereas plasma urea showed an increase. Substantial increase in the gill Na+, K+-ATPase activity was found in these fish during salinity acclimation, which remained high even after three weeks. Salinity transfer for a day produced significant increase in the intestinal Na+, K+-ATPase activity, though it remained unaffected during the long-term acclimation. Kidney Na+, K+-ATPase activity decreased on day 1 salinity challenge, but remained unaltered after prolonged acclimation. Liver Na+, K+-ATPase activity increased upon transient salinity challenge but the levels were maintained during prolonged salinity challenge. Our results indicate that salinity acclimation in climbing perch demands thyroid hormone secretion and its action and not cortisol as part of co-ordinating the acclimation processes in the early phase of salinity acclimation. The results also point to the ability of climbing perch to tolerate osmotic challenge, and the fish becomes fully adaptive to brackish water salinity of 20 ppt after three weeks.Keywords
Climbing Perch, Cortisol, Fish, Na+, K+-ATPase, Salinity Acclimation, Thyroid Hormones.- Interrenal Response in Climbing Perch (Anabas testudineus Bloch) to Nitrate Exposure: Hydromineral and Metabolic Considerations
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Authors
Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram 695581, IN
2 Department of Zoology, Fatima Mata National College, Kollam 691001, IN
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram 695581, IN
2 Department of Zoology, Fatima Mata National College, Kollam 691001, IN
Source
Journal of Endocrinology and Reproduction, Vol 12, No 2 (2008), Pagination: 73-79Abstract
The physiological response of climbing perch to water-borne nitrate, an important component of the effluents of coconut husk retting, was examined to identify the mechanism of nitrate tolerance in fish. Indices of interrenal function, and metabolic and osmoregulatory homeostasis were analyzed in fish treated with potassium nitrate. Nitrate loading in water for 48 h produced a significant increase in the plasma cortisol by a low dose (247 μM), whereas a higher dose (494 μM) had little effect. A remarkable cortisol surge was found in the nitrate-treated fish kept for recovery in clean water for 96 h, which correlated with the rise in the plasma Na+. Glucose, lactate and Na+ concentrations in the plasma showed reduction in the nitrate-exposed fish, whereas plasma urea increased. Nitrate exposure had little influence on the gill and kidney Na+, K+-ATPase activities but had a stimulatory effect on liver Na+, K+-ATPase activity, indicating a major role of liver in nitrate tolerance. Overall, the present data indicate that nitrate exposure induces an integrated stress response in climbing perch as a result of an activated interrenal axis and disturbed metabolic and hydromineral regulations. This suggests a protective role of cortisol in the regulation of nitrate tolerance in this fish.Keywords
Anabas testudineus, Fish, Interrenal, Nitrate, Na+, K+-ATPase, Metabolism, Osmoregulation, Stress.- Thyroidal and Osmoregulatory Responses in Tilapia (Oreochromis mossambicus) to the Effluents of Coconut Husk Retting
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Authors
J. Leji
1,
G. S. Babitha
2,
V. Rejitha
1,
A. S. Vijayasree
1,
J. Ignatius
2,
V. S. Peter
2,
O. V. Oommen
1,
M. C. S. Peter
1
Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram 695581, Kerala, IN
2 Department of Zoology, Fatima Mata National College, Kollam 695001, Kerala, IN
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram 695581, Kerala, IN
2 Department of Zoology, Fatima Mata National College, Kollam 695001, Kerala, IN