Carotenoid metabolic profiling and transcriptome‐genome mining reveal functional equivalence among blue‐pigmented copepods and appendicularia

Abstract

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 bluepigmented 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 nontargeted (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 the species. The pathway analysis showed that all the species can synthesize astaxanthin from b-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 b-carotene hydroxylase enzymes and putative 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.

RNA‐seq reveals regional differences in transcriptome response to heat stress in the marine snail Chlorostoma funebralis

“…Along these lines, we compared our methods to recent RNAseq studies in Molecular Ecology (Burke & Strand ; Mojib et al . ; Petek et al . ; Westram et al .…”

“…), and thus, it is important to report the details of such analyses. Along these lines, we compared our methods to recent RNAseq studies in Molecular Ecology (Burke & Strand 2014;Mojib et al 2014;Petek et al 2014;Westram et al 2014) and both our methodology itself and the reporting of our methods in the manuscript reaches, and in some instances exceeds, the standards set by these recent publications.…”

Phylogenomic analysis of Copepoda (Arthropoda, Crustacea) reveals unexpected similarities with earlier proposed morphological phylogenies

“…For eight copepod species, five transcriptome ( Caligus rogercresseyi , Lernaea cyprinacea , Tigriopus californicus , Calanus sinicus , and Acartia fossae ) and three genome sequences ( Lepeophtheirus salmonis , Mesocyclops edax , and Calanus finmarchicus ) were downloaded from the National Center for Biotechnology Information (NCBI) Sequence Read Archive (SRA) database (http://www.ncbi.nlm.nih.gov/sra) [31, 32]. Three additional crustacean species were also included: the giant tiger prawn Penaeus monodon (Malacostraca: Penaeidae), the purple barnacle Amphibalanus amphitrite (Thecostraca: Balanidae), and the brine shrimp Artemia franciscana (Branchiopoda: Artemiidae) from NCBI SRA.…”

Comparative analysis of the predominant carotenoids and chemical components in the common and orange‐muscle mutant ofHaliotis gigantea

“…The flesh of fish such as trout or salmon are enriched with carotenoids and therefore appear orange in colour (Tejera et al, ). Free carotenoids and carotenoproteins are commonly found in crustaceans and copepods (Mojib et al, ). Carotenoids have also been identified as the principal pigments present in the gonads, viscera, adductors, and feet of oysters and scallops (Fuzhi, Fei, Xiaoxi, Xiaolong, & Fengqin, ).…”