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Lipid Class, Carotenoid, and Toxin Dynamics of Karenia Brevis (Dinophyceae) During Diel Vertical Migration
Citation:
SCHAEFFER, B. A., D. KAMYKOWSKI, L. McKay, G. Sinclair, AND E. Milligan. Lipid Class, Carotenoid, and Toxin Dynamics of Karenia Brevis (Dinophyceae) During Diel Vertical Migration. JOURNAL OF PHYCOLOGY. Allen Press, Inc., Lawrence, KS, 45(1):154-163, (2009).
Impact/Purpose:
Study focuses on K. brevis toxicity, carotenoid and lipid class changes in response to different light intensity and nitrate concentrations during diel vertical migration (DMV)
Description:
Karenia brevis’ (Hansen and Moestrup) internal lipid, carotenoid, and toxin concentrations are influenced by its ability to use ambient light and nutrients for growth and reproduction. This project investigated changes of K. brevis toxicity, lipid class and carotenoid concentrations in low-light, nitrate-replete (250 µmol quanta•m-2•s-1, 80 mM NO3), high-light, nitrate-replete (960 µmol quanta•m-2•s-1, 80 mM NO3), and high-light, nitrate-reduced (960 µmol quanta•m-2•s-1, <5 mM NO3) mesocosms. Reverse-phase high performance liquid chromatography quantified the epoxidation state (EPS) of the xanthophyll-cycle pigments diadinoxanthin and diatoxanthin, and a Chromarod Iatroscan thin layer chromatography/flame ionization detection system quantified changes in lipid class concentrations. EPS did not exceed 0.20 in the low-light mesocosm, but increased to 0.65 in the high light mesocosms. Triacylglycerol and monogalactosyldiacylglycerol (MGDG) were the largest lipid classes consisting of 9.6 to 32% and 36 to 77% of total lipid respectively. Both lipid classes also experienced the greatest concentration changes between experiments. K. brevis increased EPS and toxin concentrations while decreasing its lipid concentrations under high light. K. brevis may mobilize its toxins into the surrounding environment by reducing lipid concentrations, such as sterols, limiting competition, or toxins are released because lipids are decreased in high light reducing any protective mechanism against their own toxins.