Metabolism of palmitic, linoleic, and linolenic acids in adult oysters,Crassostrea virginica

Abstract

This study investigated incorporation and metabolism of saturated [(1-14C) 16:0] and unsaturated [(1-14C) 18:2ω6 and (1-14C) 18:3ω3] fatty acids in adult eastern oysters,Crassostrea virginica Gmelin (spawned from parents obtained in 1986 from Mobjack Bay, Virginia, USA), and the influence of temperature on these processes. InC. virginica, incorporation of injected palmitic (16:0) and linolenic (18:3ω3) acids was increased when oysters which had been grown in warm water (22 to 23°C) were transfered to cold water (5 to 7°C) for 8 to 18 d. Incorporation of linoleic acid (18:2ω6) was unchanged under these conditions. The changes in concentration may have been linked to depression of metabolism in these oysters, in particular that of 16:0, which was reduced by 90%. Oxidation of incorporated fatty acids was much higher in warm than in cold water. Cold-temperature conditioning ofC. virginica altered the distribution of fatty acids among the neutral and polar lipid fractions. Long-term exposure to cold water increased the proportion of fatty acids in the polar fraction, which may be related to maintenance of membrane fluidity. Short-term exposure to cold water had the opposite effect, which may be due to increased energy requirements as the oyster adapts to new conditions. Reutilization of14C-acyl groups demonstrated de novo synthesis of 16:0 and 18:0 fatty acids. Only limited elongation and no desaturation of the administered fatty acids was observed.