Muted molecular responses to thermal stress in the Antarctic emerald rockcod (Trematomus bernacchii): Proteomic evidence and possible evolutionary mechanisms

Abstract

The Antarctic emerald rockcod ( Trematomus bernacchii) and its relatives have long been of interest to comparative physiologists, given their history of isolation in extremely cold waters and indications that they lack some or all of the classic “heat shock response.” In this study we complemented previous transcript-level analyses with a comprehensive assessment of the proteomic response to elevated temperatures across three tissues (gill, head kidney, and brain). Animals were exposed to constant conditions at one of three acclimation temperatures, after which a subset were sampled and the remaining individuals experienced an acute heat stress with or without recovery (n=5-6 per treatment). Protein expression patterns were analyzed using tissue-specific, data-independent acquisition (DIA) assay libraries on a UPLC-MS system. The expression patterns reveal a muted response to these different thermal challenges, with only a small number of proteins (out of 2721-3421 per tissue) differentially expressed for any given tissue-treatment combination. The magnitudes of expression changes were also small. These results appear to contradict relatively robust induction patterns for a subset of cellular stress response genes obtained from previous transcriptomic analyses. Furthermore, the differentially expressed proteins were not functionally enriched for any Gene Ontology or KEGG database entries, nor were the promoter regions of the corresponding genetic loci consistently enriched for any transcription factor binding motifs, including those that might be predicted to play a role in the response to hyperthermal stress (such as Hsf1 or HIF). Subsequent bioinformatics approaches within the Perciformes clade suggest modifications to the suite of proteins that regulate translation as a plausible explanation for the lack of a coordinated response to thermal stress in the Antarctic lineage. Overall, our proteomics data offer further detail into the physiological underpinnings of stenothermy in Antarctic fishes. NSF IOS-165582 to WD and an APS John F. Perkins, Jr., Research Career Enhancement Award This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.