THE EFFECT OF MERCURY AND CADMIUM ON THE FATTY ACID AND STEROL COMPOSITION OF THE MARINE DIATOM ASTERIONELLA GLACIALIS

Article abstract of DOI:10.1016/S0031-9422(00)81809-9

Key Word Index - Asterionella glacialis; diatom; sterols; lipids; fatty acids; mercury; cadmium.Cells of the marine diatom Asterionella glacialis treated with the organomercurial p-chloromercuribenzoate (PCMB) and cadmium, at growth retarding concentrations, exhibit decreased total fatty acid, polyunsaturated fatty acid and sterol contents.The level of individual fatty acids and sterols was also affected by metal treatment with significant decreases in the major polyunsaturated fatty acids 20:5Δ5,8,11,14,17, 16:1Δ9 and 16:3Δ3,6,9 in PCMB-treated, and 20:5Δ5,8,11,14,17 in cadmium-treated cells; increased cholest-5-en-3β-ol, particularly in PCMB-treated cells; and a decrease in the ratio of 24-ethylcholest-5-en-3β-ol to 24-ethylcholesta-5,24(28)Z-dien-3β-ol which was most notable in cadmium-treated cells.These results can be explained in terms of the formation of mercury and cadmium complexes with thiol-containing enzymes involved in lipid biosynthesis and metabolism, and thus provide further support for the hypothesis that transition metal toxicity is mediated by metal inactivation of physiologically essential, thiol-containing enzymes and co-factors.