The Fatty Acid and Sterol Composition of Five Marine Dinoflagellates

Abstract

The fatty acid and sterol compositions of five species of marine dinoflagellates (Scrippsiella sp. Symbiodinium microadriaticum Freud, Gymnodinium sp., Gymnodinium sanguineum Hirasaki, and Fragilidium sp.) are reported. All contained the major fatty acids that are considered common in dinoflagellates, but the proportions were quite variable, and some species contained low contents of some polyunsaturated fatty acids. Concentration ranges for the major fatty acids were: 16:0 (9.0%-24.8%), 18:4(n-3) (2.5%-11.5%), 18:5(n-3) (7.0%-43.1%), 20:5(n-3) (EPA) (1.8%-20.9%), and 22:6(n-3) (DHA) (9.9%-26.3%). Small amounts of novel very-long-chain highly unsaturated C 28 fatty acids occurred in all species. Each dinoflagellate contained a complex mixture of 4-methyl sterols and 4-desmethyl sterols. Four species contained cholesterol, although the amounts were highly variable (from 0.2% of total sterols in Scrippsiella sp. to 45.6% in Fragilidium sp.). All but G. sanguineum contained the 4-methyl sterol dinosterol, and all species contained sterols lacking a double bond in the ring system (i.e. stanols); in Scrippsiella sp. cholestanol composed 24.3% of the total sterols. Other common features of the 4-methylsterol profiles were the presence of 23,24-dimethyl alkylation and unsaturation at ⌬ 22 in the side chain. In Scrippsiella sp., four steroidal ketones were identified: cholestanone, dinosterone, 4␣,23,24-trimethyl-5␣-cholest-8(14)-en-3-one, and dinostanone. The structures of these corresponded to the major sterols in this species, suggesting that the sterols and steroidal ketones are biosynthetically linked. Steroidal ketones were not detected in the other species. Although fatty acid profiles can be used to distinguish among algal classes, they were not useful for differentiating among dinoflagellate species. In contrast, whereas some taxonomic groupings of dinoflagellates display similar sterol patterns, others, such as the gymnodinoids studied here, clearly do not. The combination of fatty acid, sterol, and steroidal ketone profiles may be useful complementary chemotaxonomic tools for distinguishing morphologically similar species. The identification of steroidal ketones supports earlier suggestions that certain dinoflagellates might be a significant source of such components in marine environments.

A Bifunctional Δ12,Δ15-Desaturase from Acanthamoeba castellanii Directs the Synthesis of Highly Unusual n-1 Series Unsaturated Fatty Acids

“…Some marine species accumulate other examples of (n-1) unsaturated fatty acids. In particular, 16:4⌬ 6,9,12,15 has been reported in a variety of marine diatoms (34 -36), dinoflagellates (37), and Rhodophyta (38). Both 16:4(n-1) and 18:4(n-1) are known to be minor but common constituents of fish oils; 18:5(n-1) has recently been detected in a fish oil concentrate.…”

Biomarkers in the stratified water column of the Landsort Deep (Baltic Sea)

“…A possible candidate, Gymnodinium beii, was described from the suboxic zones of the central Baltic Sea (Stock et al, 2009). Indeed, several Gymnodinium species are known to be heterotrophs (Strom and Morello, 1998) and some have been reported to produce dinosterol (Mansour et al, 1999). Like cholesterol and β-sitosterol, dinosterol was also found in the anoxic zone at 400 m water depth.…”

High Levels of Icosapentaenoic Acid in the Lipids of Oyster Crassostrea gigas Ranging over Both Japan and France

“…On the contrary, it is also known that some other phytoplankton and marine fungi, such as Dinophyta and Chromista, contain notable levels of DHA more than 3 of TFA Dinoflagellida [34][35][36] and Labyrinthulida [37][38][39] . The signifi cant levels of DHA in C.…”