A. B. Imbs, V. G. Rybin, V. I. Kharlamenko, L. P. T. Dang, N. T. Nguyen, K. M. Pham, L. Q. Pham - Polyunsaturated molecular species of galactolipids - markers of zooxanthellae in a symbiotic association of the soft coral Capnella sp. (Anthozoa: Alcyonacea)

BIOLOGIYA MORYA, 2015, Vol. 41, No. 6, pp. 430-436

Polyunsaturated molecular species of galactolipids - markers of zooxanthellae in a symbiotic association of the soft coral Capnella sp. (Anthozoa: Alcyonacea)

¹A.V. Zhirmunsky Institute of Marine Biology, Far East Branch, Russian Academy of Sciences, Vladivostok 690041;
²Institute of Natural Products Chemistry Vietnam Academy of Science and Technology, Hanoi, Vietnam

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The method using marker fatty acids (FAs) is widely appliedinvestigations of trophic and symbiotic relationships. In search of new lipid markers, we determined the total lipid FA composition, as well as the composition of molecular species of mono- and digalactosyl diacylglycerols (MGDG and DGDG), specific galactolipids of thylakoid membranes, in zooxanthellae (endosymbiotic dinoflagellates) of the tropical soft coral Capnella sp. Some FAs of zooxanthellae were suggested for use as marker polyunsaturated FAs (PUFAs). Thirteen molecular species of MGDG and ten molecular species of DGDG were detected by the method of high resolution tandem mass spectrometry. All marker PUFAs of zooxanthellae were found in acyl groups of galactolipids. The major molecular species of DGDG (18:4/18:4, 18:4/20:5, and 16:2/22:6) and the unique molecular species of MGDG (16:4/18:5) were described. The identification of several polyunsaturated molecular species of galactolipids containing marker FAs allowed us to suggest this lipid group as molecular lipid markers of zooxanthellae for the study of symbiont-host interactions in soft corals.

Key words: glycoglycerolipids, MGDG, DGDG, molecular species, PUFAs, marker fatty acids, corals, zooxanthellae, symbionts, high resolution tandem mass spectrometry.