CHARACTERIZATION OF STEROLS IN THE DINOFLAGELLATE GAMBIERDISCUS CAROLINIANUS AND CHLOROPLAST-BASED GALACTOLIPIDS IN G. CAROLINIANUS AND PYRODINIUM BAHAMENSE: COMPARISON TO OTHER ARMORED DINOFLAGELLATES

Abstract

This thesis delves into the chemotaxonomy of dinoflagellates. The first aspect of this study focuses on the galactolipids of Pyrodinium bahamense and Gambierdiscus carolinianus. C20/C18 galactolipids were predominant in G. carolinianus, just like other armored dinoflagellates. Conversely, P. bahamense displayed approximately equal amounts of 18:5/18:4 and 20:5/18:4 monogalactosyldiacylglycerol (DGDG), placing it in an intermediary position between the two clusters. P. bahamense also displayed a near near total lack of detectable monogalactosyldiacylglycerol (MGDG) with only trace amounts of 18:5/18:4 and 18:4/18:4 MGDG in some of the isolates. Other dinoflagellates possess more DGDG than MGDG but it was significant. These results were consistent for P. bahamense grown under two levels of irradiance (at below saturating intensities). This study presents the first characterization of galactolipid composition in these two species and the first description of a peridinin-containing species generally lacking MGDG. The second aspect of this study is also the first exploration of sterol composition in G. carolinianus. Nine sterols were identified, with cholesterol, 24-methylcholesta-5-en-3β-ol, and dinosterol being predominant. Comparative analysis with other armored dinoflagellates revealed shared sterols and distinct abundance patterns, notably a higher presence of 24-methylcholesta-5-en-3β-ol in G. carolinianus. This suggests its potential as a chemotaxonomic marker for the species. Overall, the study provides galactolipid profiles for P. bahamense and G. carolinianus and a sterol profile for G. carolinianus.