title: Acclimation ofSolea senegalensisto different ambient temperatures: implications for thyroidal status and osmoregulation.
abstract: We have investigated the regulation of thyroidal status and osmoregulatory capacities in juveniles from the teleostSolea senegalensisacclimated to different ambient temperatures. Juveniles, raised in seawater at 19°C, were acclimated for 3 weeks to temperatures of 12, 19 and 26°C. Since our preliminary observations showed that at 12°C feed intake was suppressed, our experimental design controlled for this factor. The concentration of branchial Na+,K+-ATPase, estimated by measurements of enzyme activity at the optimum temperature of this enzyme (37°C), did not change. In contrast, an increase in Na+,K+-ATPase activity (measured at 37°C), was observed in the kidney of 12°C-acclimated fish. In fish acclimated to 12°C, the hepatosomatic index had increased, which correlated with increased plasma levels of triglycerides and non-esterified fatty acids. Plasma cortisol levels did not differ significantly between the experimental groups. In liver and gills, the amount of iodothyronine deiodinases that exhibit thyroid hormone outer ring deiodination was up-regulated only when fish did not feed. When assayed at the acclimation temperature, kidney deiodinase activities were similar, indicating a temperature-compensation strategy. 3,5,3'-triiodothyronine (T3) tissue concentrations in gills and kidney did not differ significantly between experimental groups. However, at 12°C, lower T3 tissue levels were measured in plasma and liver. We conclude thatS. senegalensisadjusts its osmoregulatory system to compensate for the effects of temperature on electrolyte transport capacity. The organ-specific changes in thyroid hormone metabolism at different temperatures indicate the involvement of thyroid hormones in temperature acclimation.
authors.affiliation: Centro Andaluz Superior de Estudios Marinos, Facultad de Ciencias del Mar y Ambientales, Departamento de Biología, Universidad de Cádiz, Av. República Saharahui s/n, 11510 Puerto Real, Cádiz Spain ; Institute for Water and Wetland Research, Faculty of Science, Department of Animal Physiology, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Arjona
authors.affiliation: Centro Andaluz Superior de Estudios Marinos, Facultad de Ciencias del Mar y Ambientales, Departamento de Biología, Universidad de Cádiz, Av. República Saharahui s/n, 11510 Puerto Real, Cádiz Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Ruiz-Jarabo
authors.affiliation: Centro Andaluz Superior de Estudios Marinos, Facultad de Ciencias del Mar y Ambientales, Departamento de Biología, Universidad de Cádiz, Av. República Saharahui s/n, 11510 Puerto Real, Cádiz Spain ; Instituto de Zoología, Facultad de Ciencias, Universidad Austral de Chile, casilla 567, Valdivia, Chile.
authors.forename: Luis
authors.initials: L
authors.lastname: Vargas-Chacoff
authors.affiliation: Centro Andaluz Superior de Estudios Marinos, Facultad de Ciencias del Mar y Ambientales, Departamento de Biología, Universidad de Cádiz, Av. República Saharahui s/n, 11510 Puerto Real, Cádiz Spain.
authors.forename: María P
authors.initials: MP
authors.lastname: Martín Del Río
authors.affiliation: Institute for Water and Wetland Research, Faculty of Science, Department of Animal Physiology, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors.forename: Gert
authors.initials: G
authors.lastname: Flik
authors.affiliation: Centro Andaluz Superior de Estudios Marinos, Facultad de Ciencias del Mar y Ambientales, Departamento de Biología, Universidad de Cádiz, Av. República Saharahui s/n, 11510 Puerto Real, Cádiz Spain.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Mancera
authors.affiliation: Institute for Water and Wetland Research, Faculty of Science, Department of Animal Physiology, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors.forename: Peter H M
authors.initials: PH
authors.lastname: Klaren