Data from: Carotenoid metabolic profiling and transcriptome-genome mining reveal functional equivalence among blue-pigmented copepods and appendicularia

The tropical oligotrophic oceanic areas are characterized by high water
transparency and annual solar radiation. Under these conditions, a large
number of phylogenetically diverse mesozooplankton species living in the
surface waters (neuston) are found to be blue pigmented. In the present
study, we focused on understanding the metabolic and genetic basis of the
observed blue phenotype functional equivalence between the blue pigmented
organisms from the phylum Arthropoda, subclass copepoda (Acartia fossae)
and the phylum Chordata, class appendicularia (Oikopleura dioica) in the
Red Sea. Previous studies have shown that carotenoid protein complexes are
responsible for blue coloration in crustaceans. Therefore, we performed
carotenoid metabolic profiling using both targeted and non-targeted
(high-resolution mass spectrometry) approaches in four different
blue-pigmented genera of copepods and one blue-pigmented species of
appendicularia. Astaxanthin was found to be the principal carotenoid in
all species. The pathway analysis showed that all species can synthesize
astaxanthin from β-carotene, ingested from dietary sources, via
3-hydroxyechinenone, canthaxanthin, zeaxanthin, adonirubin or
adonixanthin. Further, using de novo assembled transcriptome of blue A.
fossae (subclass copepoda) we identified highly expressed homologous
β-carotene hydroxylase enzymes and carotenoid binding proteins responsible
for astaxanthin formation and the blue phenotype. In blue O. dioica (class
appendicularia), corresponding putative genes were identified from the
reference genome. Collectively, our data provide molecular evidences for
the bioconversion and accumulation of blue astaxanthin-protein complexes
underpinning the observed ecological functional equivalence and adaptive
convergence among neustonic mesozooplankton.