Temperature during early development has long-term effects on microRNA expression in Atlantic cod

Area of Science:

• Marine Biology
• Developmental Biology
• Molecular Ecology

Background:

• Environmental temperature significantly influences the life cycle of aquatic ectotherms.
• Understanding molecular mechanisms of temperature acclimation is vital for predicting global warming effects on marine populations.
• MicroRNAs (miRNAs) are key regulators of adaptive plasticity, but their role in thermal responses is understudied.

Purpose of the Study:

• To investigate how temperature and temperature shifts during early ontogeny affect the miRNA repertoire in Atlantic cod (Gadus morhua).
• To determine if thermal experience during development has long-term consequences on the miRNA profile of Atlantic cod.

Main Methods:

• Characterization of miRNA expression across different developmental stages and juvenile tissues using next-generation sequencing.
• Identification of novel and known precursor and mature miRNAs.
• Differential expression analysis of miRNAs under varying temperature regimes.
• Validation of specific differentially expressed miRNAs using LNA-based rt-qPCR.

Main Results:

• Identified 389 putative miRNA precursor loci, including 120 novel precursors and 281 mature miRNAs.
• Observed stage- and tissue-enriched expression for certain miRNAs.
• Found differential expression of key miRNAs (e.g., miR-17~92 cluster, myomiRs, neuromiRs) across different temperature regimes.
• Revealed long-term effects of embryonic incubation temperature on miRNA expression in juvenile pituitary, gonad, and liver, but not brain.

Conclusions:

• Elevated temperatures during embryonic and larval development significantly alter the miRNA profile of Atlantic cod, both short-term and long-term.
• These findings suggest that rising sea temperatures may impact the life history of Atlantic cod through miRNA-mediated regulatory pathways.