Cytotoxic and Hemolytic Activities of Extracts of the Fish Parasite Dinoflagellate .

The dinoflagellate is the etiological agent of a parasitic disease named amyloodiniosis. Mortalities of diseased fish are usually attributed to anoxia, osmoregulatory impairment, or opportunistic bacterial infections. Nevertheless, the phylogenetic proximity of to a group of toxin-producing dinoflagellates from , and genera suggests that it may produce toxin-like compounds, adding a new dimension to the possible cause of mortalities in outbreaks. To address this question, extracts prepared from different life stages of the parasite were tested in vitro for cytotoxic effects using two cell lines derived from branchial arches (ABSa15) and the caudal fin (CFSa1) of the gilthead seabream (), and for hemolytic effects using erythrocytes purified from the blood of gilthead seabream juveniles. Cytotoxicity and a strong hemolytic effect, similar to those observed for toxins, were observed for the less polar extracts of the parasitic stage (trophont). A similar trend was observed for the less polar extracts of the infective stage (dinospores), although cell viability was only affected in the ABSa15 line. These results suggest that produces tissue-specific toxic compounds that may have a role in the attachment of the dinospores' and trophonts' feeding process.