Adaptation and Resistance: Cellular Physiological Changes and Gene Expression Variations in Karenia Selliformis Under Ocean Acidification

Abstract

Ocean acidification, a consequence of the increased partial pressure of carbon dioxide (pCO2) in seawater, disrupts the marine carbonate system and poses significant challenges to marine microalgae and ecosystems. This study explores the effects of ocean acidification on the harmful marine dinoflagellate Karenia selliformis by evaluating its physiological responses and gene expression variations under simulated acidification condition (1,000 ppm pCO2). Our findings revealed that while cell density remained consistent between the control and acidification conditions, the activity of the caspase-3 enzyme and the rate of apoptosis were lower in the acidified group during the pre-growth phase than that in the control group. Moreover, the production of phycotoxin gymnodimine-A increased under the acidified condition. The physiological response of K. selliformis to ocean acidification varied at the different growth stage, exhibiting an upregulation of energy metabolism during the exponential phase and a reduction in energy metabolism during the late lag phase and stationary phase. This study indicates that K. selliformis is capable of modulating gene expression in order to balance energy metabolism and stress resistance. This capacity can contribute to the ability of K. selliformis to withstand the effects of ocean acidification. Consequently, the detrimental effects of K. selliformis blooms would potentially be intensified with the aggravation of ocean acidification.

Keywords: ocean acidification, Gymnodimines, Transcriptome, Apoptosis