(n-3) and (n-6) PUFA as biochemical markers for developmental stages of brine shrimp developing toward ‘dumpy’ or ‘slender’ adults

Abstract

Polyunsaturated fatty acids (PUFA) of the (n-3) and (n-6) series are involved in many physiological processes. We investigated their importance during development toward the adult brine shrimp. PUFA families and specific PUFA were identified that can be used as biochemical markers of specific developmental stages. Depending on the diet, the adults assumed different phenotypes (‘dumpy’ or ‘slender’). Principal components analysis showed that at hatching, all same-batch-larvae are distinguished from other developmental stages by high levels of 18:2 (n-6) and 18:3 (n-3) as well as 18:4 (n-3) and 20:5 (n-3) PUFA. At the larval-to-juvenile molt, two groups of brine shrimp emerged: those showing increasing levels of 20:4 (n-3), later to develop into ‘slender’ adult brine shrimp, and those having increased levels of 18:4 (n-3) and 18:3 (n-6) becoming future ‘dumpy’ adults. PUFA content was low in all juveniles. Both juvenile groups were characterized by 18:3 (n-6) PUFA. ‘Slender’ adults, developing from larvae raised on a diet with an 18:2/18:3 ratio of 5.95 and a PUFA/SFA ratio of 0.45, had predominantly high levels of 20:4 (n-3), but also 18:3 (n-6). ‘Dumpy’ adults, derived from larvae grown on a diet with an 18:2/18:3 ratio of 1.3 and PUFA/SFA ratio of 4.11, had high levels of 18:2 (n-6) (PCA results) and 20:3 (n-6). These data suggest that high levels of PUFA from the (n-3) or the (n-6) PUFA series are differentially accumulated in ‘slender’ ((n-3) PUFA) and in ‘dumpy’ brine shrimp ((n-6) PUFA).