Agonistic encounters and cellular angst: social interactions induce heat shock proteins in juvenile salmonid fish

Abstract

Juvenile salmonid fish readily form dominance hierarchies when faced with limited resources. While these social interactions may result in profound behavioural and physiological stress, it is unknown if this social stress is evident at the level of the cellular stress response-specifically, the induction of stress or heat shock proteins (Hsps). Thus, the goal of our study was to determine if Hsps are induced during hierarchy formation in juvenile rainbow trout (Oncorhynchus mykiss). To this end, we measured levels of three Hsps, Hsp70, Hsc (heat shock cognate)70 and Hsp90 in the white muscle, liver and brain of trout that had been interacting for 36 h, 72 h or 6 days. Our data indicate that Hsps are induced in both dominant and subordinate fish in a time-and tissue-specific manner. In further mechanistic experiments on fasted and cortisol-treated fish, we demonstrated that high plasma cortisol does not affect Hsp induction in trout white muscle or liver, but both conditions may be part of the mechanism for Hsp induction with social stress in the brain. We conclude that the behavioural and physiological stress experienced by juvenile rainbow trout in dominance hierarchies can be extended to the induction of Hsps.

Do group dynamics affect colour morph clines during a range shift?

“…One possibility is that cold tolerance is directly affected by both individual personality and the levels of social stress that the individual has recently experienced. A similar mechanism has recently been reported for salmonid fish, in which subordinate individuals exhibit overexpression of stress‐inducible chaperone proteins in comparison with dominant fish, in response to social stress and prior to any thermal challenges (Currie et al ., ; LeBlanc et al ., ). Thus, social stress may have a pleiotropic effect on thermal stress‐response enzyme pathways that mimics cold weather acclimation.…”

Chaperone roles for TMAO and HSP70 during hyposmotic stress in the spiny dogfish shark (Squalus acanthias)

“…Soluble protein was extracted from frozen gill and white muscle tissue as in Currie et al (2010). RBCs were diluted 1:1 in elasmobranch saline [as above but with 150 units/mL heparin (i.e., "super heparinzed")] lacking urea or TMAO and were then manually homogenized with needles (16-25 gage) to destroy clot fibers.…”

The Influence of Social Status on Hepatic Glucose Metabolism in Rainbow TroutOncorhynchus mykiss

“…Fasted (mass g, ) and cortisol-89.5 ‫ע‬ 3.9 N p 20 treated (mass g, ) fish were held in groups 102 ‫ע‬ 4.5 N p 31 of 10-12 fish in tanks of ∼230 L, conditions that were found in a previous study to minimize hierarchy formation. Food was withheld from fasted fish for 5 d. On the basis of previous studies Currie et al 2010), cortisol-treated fish received a cocoa-butter pellet (0.005 mL g Ϫ1 fish; Now Personal Care 100% pure cocoa butter) containing dissolved cortisol (110 mg kg Ϫ1 fish hydrocortisone 21-hemisuccinate; Sigma-Aldrich). The cocoa butter was injected as a liquid into the peritoneal cavity of a fish anesthetized to the point of losing equilibrium in a solution of ethyl-paminobenzoate (0.065 g L Ϫ1 ); the liquid solidified rapidly within the fish, acting as a slow-release cortisol implant.…”