Meeting Abstract
Astaxanthin is the dominant carotenoid pigment found in the marine copepod, Tigriopus californicus, giving these animals red coloration along with protection from UV radiation in their shallow-water rock pool habitat. Like all metazoans, T. californicus must convert carotenes and hydroxy-carotenoids present in their algal diet to astaxanthin, a ketocarotenoid. Other astaxanthin-pigmented crustaceans have been shown to use a precursor-specific bioconversion pathway to astaxanthin. The aim of this study was to identify the metabolic pathway used by T. californicus for the production of astaxanthin. Copepods were maintained on a carotenoid-free diet on which they lost all carotenoid coloration. To identify which pathways are used for astaxanthin production, copepods were fed one of three microalgae strains that contained particular dietary carotenoids (lutein, zeaxanthin, or both) that are precursors to specific astaxanthin bioconversion pathways. We found that copepods from each precursor pigment group were able to produce astaxanthin. Previous work on carotenoid metabolism in other Harpacticoid copepods revealed a single astaxanthin pathway. Here we show that T. californicus has facultative control of conversion pathways for the production of astaxanthin. Strong selection for photoprotection from UV radiation by ketocarotenoids in this species likely drives the plasticity of astaxanthin production pathways.
