Oxidative stress, apoptosis, and transcriptional responses in Acropora microphthalma under simulated diving activities

This study simulated the effects of diving activities on the physiology, enzymatic, and transcriptional responses of Acropora microphthalma. Touching had less impact on Fv/Fm, but a few zooxanthellae were decreased and minor MDA was elevated. Caspase 3 was activated to remove damaged cells, and SOD was increased to alleviate oxidative damage. Under double or triple diving stress, we observed mass loss of zooxanthellae and Fv/Fm, a significant increase in MDA, and SOD, CAT was activated in response to oxidative stress. Transcriptome analyses showed that corals activated immune signaling pathways, anti-oxidation pathways, lysosomal, phagosomal, and cellular autophagy pathways to manage oxidation stress. Moreover, it up-regulated carbohydrate metabolisms, as well as lipopolysaccharide metabolism, glycosphingolipid biosynthesis, photorespiration, amino acid metabolism, and fatty acid beta-oxidation, but down-regulated fatty acid biosynthesis to answer energy insufficiency. This research supported that even in a short time, improper diving activities could have a serious impact on coral health.