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 individual tissue extracts obtained from specimens of Cadlina luteo-marginata collected 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 populations, among individuals of a population, and among body tissues of individual specimens. The major biosynthetic product, albicanyl acetate (1), has the same concentration in both British Columbia and California populations, while the British Columbia population contains greater total amounts of 2 and 3 than the California population. Within individuals from one population, the largest proportion of endogenous metabolites is in the dorsum, specifically 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 inversely correlated with availability of structurally similar compounds from dietary sources. This suggests that the de novo biosynthesis of defensive compounds might be regulated according to need.