Morphological and Metabolic Adaptations to Increasing Temperature: Insights from the In Vitro Model of Maraena Whitefish

Physiological changes in animals induced by environmental shifts in aquatic ecosystems can be studied using fish cell lines derived from vulnerable species. Therefore, we investigated how environmental shifts—specifically, an increase of 5 °C in temperature—impact the physiology of the cell line CMAfin1 derived from maraena whitefish (Coregonus maraena). Cellular growth, morphology, and metabolic responses were examined under two growth conditions: a control temperature of 20 °C and an elevated temperature of 25 °C. Using trypan blue staining, automated cell counting, phase contrast microscopy, and actin staining, we observed morphological changes in the cells. Metabolic functions were assessed using a Seahorse XFe96 Flux Analyzer, focusing on the bioenergetic capacities of mitochondrial respiration and glycolytic activity. Hyperthermia resulted in faster growth rates but reduced cell size in the CMAfin1 cell line. The cells’ metabolic activity (mitochondrial respiration and glycolytic activity) was inhibited, leading to a quiescent energy state. Our findings indicate reduced motility and altered intercellular communication at higher temperatures. The results highlight the potential of in vitro models to study environmental stress on fish physiology and emphasize the value of fish cell lines for understanding metabolic responses.