期刊
COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR & INTEGRATIVE PHYSIOLOGY
卷 178, 期 -, 页码 82-89出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.cbpa.2014.08.008
关键词
Euryhaline; Ionocyte; Ionoregulation; NHE; NKCC; CFTR; Sodium; Chloride; Salinity transfer
资金
- Harvey Weil Sportsman Conservation Award from the Rotary Club of Corpus Christi
- National Science Foundation [EF 1315290, OCE 1062745]
- de Amparo a Pesquisa do Estado de Sao Paulo [FAPESP - 2013/12950-3]
- Division Of Ocean Sciences
- Directorate For Geosciences [1062745] Funding Source: National Science Foundation
Red drum, Sciaenops ocellatus, is an estuarine-dependent fish species commonly found in the Gulf of Mexico and along the coast of the southeastern United States. This economically important species has demonstrated freshwater tolerance; however, the physiological mechanisms and costs related to freshwater exposure remain poorly understood. The current study therefore investigated the physiological response of red drum using an acute freshwater transfer protocol. Plasma osmolality, Cl-, Mg2+ and Ca2+ were all significantly reduced by 24 h post-transfer; Cl- and Mg2+ recovered to control levels by 7 days post-transfer. No effect of transfer was observed on muscle water content; however, muscle Cl- was significantly reduced. Interestingly, plasma and muscle Na+ content was unaffected by freshwater transfer. Intestinal fluid was absent by 24 h post-transfer indicating cessation of drinking. Branchial gene expression analysis showed that both CFTR and NKCC1 exhibited significant down-regulation at 8 and 24 h post-transfer, respectively, although transfer had no impact on NHE2, NHE3 or Na+, K+ ATPase (NKA) activity. These general findings are supported by immunohistochemical analysis, which revealed no apparent NKCC containing cells in the gills at 7 days post transfer while NKA cells localization was unaffected. The results of the current study suggest that red drum can effectively regulate Na+ balance upon freshwater exposure using already present Na+ uptake pathways while also down-regulating ion excretion mechanisms. (C) 2014 Elsevier Inc. All rights reserved.
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