The lipid composition of the marine dinoflagellate Zooxanthella nutricula, a polycystine radiolarian symbiont

Abstract

Dinoflagellates are important primary producers in their marine and freshwater environments, and they form symbiotic relationships with larger marine organisms. Previous research has explored symbiotic relationships such as cnidarian symbioses with Symbiodinium dinoflagellates. However, little research addresses the symbiotic relationship between radiolarians and their symbionts, such as the marine dinoflagellate Zooxanthella nutricula. An important aspect of dinoflagellate symbiosis involves the exchange of metabolites such as the transfer of lipids from the symbiont to the host. This research aimed to identify the lipid content, particularly that of sterols and fatty acidcontaining galactolipids, of Z. nutricula. The major sterol identified was 22- dehydrocholesterol, which does not tend to be a dominant sterol among dinoflagellates. The major galactolipid was 18:5/18:5 MGDG, and all galactolipids identified were C18/C18 forms of MGDG and DGDG. These results along with future research about radiolarian lipids should elucidate the role of sterols and fatty acids in dinoflagellateradiolarian symbiosis.