Cold stress poses a significant challenge to aquatic organisms, affecting their survival, growth, and metabolic processes. This review explores the molecular mechanisms by which fish, crustaceans, and mollusks respond to cold stress, highlighting the shared and species-specific pathways that facilitate adaptation. Common responses to cold stress include modulation of energy metabolism, regulation of oxidative stress, immune responses, and maintenance of proteostasis. In particular, the activation of the adenosine 5′-monophosphate-activated protein kinase (AMPK) and mechanistic target of rapamycin (mTOR) pathways plays a critical role in regulating energy balance and autophagy in response to low temperatures. Furthermore, we examine the specific adaptive mechanisms employed by different groups of aquatic organisms. Fish utilize pathways such as peroxisome proliferator-activated receptor alpha/peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPAR/PGC-1α) and fatty acid oxidation to optimize energy utilization and improve cold tolerance. Crustaceans rely on crustacean hyperglycemic hormone (CHH) signaling and AMPK pathway activation, while mollusks employ metabolic suppression and glycogen storage to survive cold exposure. Moreover, the regulation of autophagy and apoptosis, mediated by p53 and cyclin-dependent kinase 1 (Cdk1), ensures the survival of healthy cells under prolonged cold stress, with autophagy maintaining energy homeostasis and apoptosis eliminating damaged cells. This review also discusses the role of molecular chaperones like heat shock protein 70 (HSP70) and the ubiquitin-proteasome system (UPS) in protein homeostasis, highlighting their importance to protect cells under cold stress. The combined action of these molecular pathways allows aquatic organisms to cope with and adapt to cold environments, ensuring cellular integrity and enhancing survival. Future research should focus on integrating molecular, physiological, and ecological approaches to better understand cold tolerance mechanisms and improve aquaculture practices under climate change scenarios.
Li et al. (Mon,) studied this question.