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Osmoregulation and branchial plasticity after acute freshwater transfer in red drum, Sciaenops ocellatus.

Abstract

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 24h post-transfer; Cl⁻ and Mg²⁺ recovered to control levels by 7days 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 24h post-transfer indicating cessation of drinking. Branchial gene expression analysis showed that both CFTR and NKCC1 exhibited significant down-regulation at 8 and 24h 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 7days 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.

Authors+Show Affiliations

University of Texas Marine Science Institute, Austin, TX 78373, USA.University of Texas Marine Science Institute, Austin, TX 78373, USA.University of Texas Marine Science Institute, Austin, TX 78373, USA. Electronic address: a.esbaugh@austin.utexas.edu.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

25152533

Citation

Watson, Caroline J., et al. "Osmoregulation and Branchial Plasticity After Acute Freshwater Transfer in Red Drum, Sciaenops Ocellatus." Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology, vol. 178, 2014, pp. 82-9.
Watson CJ, Nordi WM, Esbaugh AJ. Osmoregulation and branchial plasticity after acute freshwater transfer in red drum, Sciaenops ocellatus. Comp Biochem Physiol, Part A Mol Integr Physiol. 2014;178:82-9.
Watson, C. J., Nordi, W. M., & Esbaugh, A. J. (2014). Osmoregulation and branchial plasticity after acute freshwater transfer in red drum, Sciaenops ocellatus. Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology, 178, pp. 82-9. doi:10.1016/j.cbpa.2014.08.008.
Watson CJ, Nordi WM, Esbaugh AJ. Osmoregulation and Branchial Plasticity After Acute Freshwater Transfer in Red Drum, Sciaenops Ocellatus. Comp Biochem Physiol, Part A Mol Integr Physiol. 2014;178:82-9. PubMed PMID: 25152533.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Osmoregulation and branchial plasticity after acute freshwater transfer in red drum, Sciaenops ocellatus. AU - Watson,Caroline J, AU - Nordi,Wiolene M, AU - Esbaugh,Andrew J, Y1 - 2014/08/22/ PY - 2014/06/12/received PY - 2014/07/21/revised PY - 2014/08/13/accepted PY - 2014/8/26/entrez PY - 2014/8/26/pubmed PY - 2015/6/2/medline KW - CFTR KW - Chloride KW - Euryhaline KW - Ionocyte KW - Ionoregulation KW - NHE KW - NKCC KW - Salinity transfer KW - Sodium SP - 82 EP - 9 JF - Comparative biochemistry and physiology. Part A, Molecular & integrative physiology JO - Comp. Biochem. Physiol., Part A Mol. Integr. Physiol. VL - 178 N2 - 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 24h post-transfer; Cl⁻ and Mg²⁺ recovered to control levels by 7days 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 24h post-transfer indicating cessation of drinking. Branchial gene expression analysis showed that both CFTR and NKCC1 exhibited significant down-regulation at 8 and 24h 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 7days 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. SN - 1531-4332 UR - https://www.unboundmedicine.com/medline/citation/25152533/Osmoregulation_and_branchial_plasticity_after_acute_freshwater_transfer_in_red_drum_Sciaenops_ocellatus_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1095-6433(14)00173-1 DB - PRIME DP - Unbound Medicine ER -