Geographic variation and tissue distribution of endogenous terpenoids in the Northeastern Pacific Ocean dorid nudibranch Cadlina luteomarginata: Implications for the regulation of de novo biosynthesis

Gas chromatography (GC) analyses of whole animal skin extracts and individu al tissue extracts obtained from specimens of Cadlina luteo-marginata colle cted in British Columbia and southern California were used to determine if concentrations of the nudibranch's biosynthetic products-albicanyl acetate (1), cadlinaldehyde (2), and luteone (3)-vary significantly between two pop ulations, among individuals of a population, and among body tissues of indi vidual specimens. The major biosynthetic product, albicanyl acetate (1), ha s the same concentration in both British Columbia and California population s, while the British Columbia population contains greater total amounts of 2 and 3 than the California population. Within individuals from one populat ion, the largest proportion of endogenous metabolites is in the dorsum, spe cifically in the mantle dermal formations and margins. The GC analyses show that across geographically separated populations and within geographically localized populations the concentration of endogenous metabolites is inver sely correlated with availability of structurally similar compounds from di etary sources. This suggests that the de novo biosynthesis of defensive com pounds might be regulated according to need.