Facing warm temperatures during migration: cardiac mRNA responses of two adult Oncorhynchus nerka populations to warming and swimming challenges. Issue 5 (31st March 2014)

• Record Type: Journal Article
• Authors: Anttila, K.; Eliason, E. J.; Kaukinen, K. H.; Miller, K. M.; Farrell, A. P.
• Is Part Of: Journal of fish biology. Volume 84:Issue 5(2014)
• Page Start: 1439
• Page End: 1456
• Publication Date: 2014-03-31
• Subjects: Fishes -- Periodicals; Fishes -- Great Britain -- Periodicals; 597
• DOI: 10.1111/jfb.12367
• Languages: English
• ISSNs: 0022-1112

Abstract

<abstract abstract-type="main" id="jfb12367-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p id="jfb12367-para-0001">The main findings of the current study were that exposing adult sockeye salmon <italic>Onchorhynchus nerka</italic> to a warm temperature that they regularly encounter during their river migration induced a heat shock response at an mRNA level, and this response was exacerbated with forced swimming. Similar to the heat shock response, increased immune defence‐related responses were also observed after warm temperature treatment and with a swimming challenge in two different populations (Chilko and Nechako), but with some important differences. Microarray analyses revealed that 347 genes were differentially expressed between the cold (12–13° C) and warm (18–19° C) treated fish, with stress response (GO:0006950) and response to fungus (GO:0009620) elevated with warm treatment, while expression for genes involved in oxidative phosphorylation (GO:0006119) and electron transport chain (GO:0022900) elevated for cold‐treated fish. Analysis of single genes with real‐time quantitative PCR revealed that temperature had the most significant effect on mRNA expression levels, with swimming and population having secondary influences. Warm temperature treatment for the Chilko population induced expression of heat shock protein (<italic>hsp</italic>) <italic>90α</italic>, <italic>hsp90β</italic> and <italic>hsp30</italic> as well as <italic>interferon‐inducible protein</italic>. The Nechako population, which is known to have a narrower thermal tolerance window than the Chilko population, showed even more pronounced stress responses to the warm treatment and there was significant interaction between population and temperature treatment for <italic>hsp90β</italic> expression. Moreover, significant interactions were noted between temperature treatment and swimming challenge for <italic>hsp90α</italic> and <italic>hsp30</italic>, and while swimming challenge alone increased expression of these <italic>hsp</italic>s, the expression levels were significantly elevated in warm‐treated fish swum to exhaustion. In conclusion, it seems that adult <italic>O. nerka</italic> currently encounter conditions that induce several cellular defence mechanisms during their once‐in‐the‐lifetime migration. As river temperatures continue to increase, it remains to be seen whether or not these cellular defences provide sufficient protection for all <italic>O. nerka</italic> populations.</p> </abstract>