The β-oxidation pathway is downregulated during diapause termination in Calanus copepods

Area of Science:

• Marine Biology
• Molecular Ecology
• Biochemistry

Background:

• Calanus copepods are vital to marine ecosystems due to their high lipid content, serving as a crucial food source for juvenile fish.
• Lipid catabolism fuels energy needs during diapause (dormancy) in the copepodite stage 5 (C5), but pathways for diapause termination are poorly understood.

Purpose of the Study:

• To investigate lipid degradation pathways during diapause termination in Calanus copepods.
• To characterize transcriptional changes and identify key regulators of energy metabolism during C5 development and diapause termination.

Main Methods:

• Analysis of lipid fullness in C5 copepods throughout development.
• Generation and analysis of transcriptional profiles (gene expression) during diapause termination.
• Bioinformatic identification of potential master regulators of energy metabolism.

Main Results:

• Lipid content decreased linearly with development, while β-oxidation gene expression was higher in early C5s.
• Four potential master regulators of energy metabolism were upregulated in early C5s compared to later stages.
• An enzyme crucial for the carnitine shuttle, involved in fatty acid transport, was found to be absent in the calanoid lineage.

Conclusions:

• Lipid catabolism is active during diapause termination, with specific gene expression patterns.
• The absence of a carnitine shuttle enzyme suggests unique lipid metabolism adaptations in calanoid copepods.
• Accurate species identification using molecular methods is essential for Calanus research, as exemplified by the co-occurrence of C. finmarchicus and C. glacialis.