A method for detecting acid phosphatase activity in corals

To investigate the digestive response of corals, we detected acid phosphatase (ACPase) activity in coral tissues using Gomori's staining method. ACPase activity signals were observed under non-feeding conditions, and their intensity was reduced following antibiotic treatment. These findings suggest that ACPase activity also reflect bacterial predation by corals, indicating that antibiotic exposure is essential for detecting the digestive activity associated with a specific food source. Corals fed with Artemia exhibited such signals with pre-exposure to antibiotics. However, regardless of feeding and pre-exposure to antibiotics, the ACPase activity was strongly detected in planula larvae. Transmission electron microscopy revealed that the ACPase-positive granules were localized in lysosomes and phagolysosomes, consistent with observations in mammals. The method detecting the digestive response of corals is expected to elucidate the process in feeding response as well as in the coral-algal symbiotic process.