2006/12/05 by Adelaide C. E. Rhodes, Adelaide Rhodes · 1 citation
Medicine · Earth and Planetary Sciences · Environmental Science · #Antioxidant Activity and Oxidative Stress #Marine and coastal ecosystems #Environmental Toxicology and Ecotoxicology
paper · doi:10.1093/plankt/fbl068
Nitokra lacustris, a euryhaline harpacticoid copepod, was reared on two diets, which varied in composition and relative quantities of carotenoid pigments, and analyzed for differences in tissue carotenoid composition. Carotenoid compositions were analyzed by means of reverse-phase high performance liquid chromatography (RP-HPLC). Total amounts of unesterified astaxanthin were quantified in the two populations by means of an isocratic HPLC procedure. Carotenoid composition and total astaxanthin content for adult copepods differed between the two diets. Copepod populations fed the live microalga Tetraselmis suesica averaged 696 µg carotenoids (g dry weight)−1 and 185 µg astaxanthin (g dry weight)−1 while copepod populations fed a formulated diet with high levels of lycopene, beta-carotene and alpha-carotene averaged 24.3 mg carotenoids (g dry weight)−1 and 650 µg astaxanthin (g dry weight)−1. Neither diet contained canthaxanthin or astaxanthin, suggesting that the copepods were synthesizing the astaxanthin from precursor pigments. The absence of canthaxanthin and echinenone coupled with the presence of other intermediary carotenoid pigments suggests that the carotenoid conversion pathway of N. lacustris differs from that described for calanoid copepods and other marine crustaceans. N. lacustris may utilize the β-carotene → zeaxanthin → β-doradexanthin (adonixanthin) → astaxanthin pathway of conversion rather than the β-carotene → echninenone → canthaxanthin → astaxanthin pathway proposed for other copepods. Thus, diets containing higher amounts of β-carotene and zeaxanthin would be more likely to produce high levels of astaxanthin in this species.