Pressure tolerance of brine shrimp (Artemia)

ABSTRACT Life adapts to various environments, including high temperatures and high pressures. The brine shrimp Artemia was used to investigate the tolerance to hydrostatic pressure up to 750 bar. The swimming activity of Artemia nauplii (larval form) decreased as pressure increased, and the activity became null at 400 bar and above. Interestingly, at 300 bar and less, the swimming activity gradually recovered even under pressure within a short period of time. Up to 500 bar, the activity was reversibly recovered by reducing the pressure to 1 bar. These results could be explained by reversible responses of protein functions and membrane structures, as well as temporal adaptation of cell functions to pressure. The upper limit pressure at which the swimming activity was reversible or irreversible matched that for macromolecular synthesis (500 bar). Altogether, these results indicate that eukaryotes and prokaryotes can temporarily adapt to a high pressure of 500 bar and less.