Identification of Genes for Synthesis of the Blue Pigment, Biliverdin IXα, in the Blue CoralHeliopora coerulea

Abstract

Heliopora coerulea is the only species in the subclass Octocorallia that has a crystalline aragonite skeleton. The skeleton has been reported to contain the blue pigment, biliverdin IXα, which is formed by heme oxygenase (HO) during heme decomposition. There is little information regarding gene expression in H. coerulea; therefore, the biosynthesis pathway for biliverdin IXα is poorly understood. To identify the genes related to heme synthesis and degradation, metatranscripts of H. coerulea and its symbiont Symbiodinium spp. were sequenced and separated from the host- and symbiont-derived sequences. From the metatranscriptome analyses, all genes for heme synthesis and three HOs were isolated from the host and symbiont. From our phylogenetic and amino acid analysis, we noted that one of the HO isoforms in the host coral was predicted to possess HO activity. However, biliverdin reductase, which reduces biliverdin to bilirubin, was not identified in the present study. Similarly, biliverdin reductase was not identified in the transcripts of the red coral Corallium rubrum, a species that also belongs to Octocorallia. However, genes related to heme synthesis and HO were found in C. rubrum. We speculate that Heliopora coerulea can produce biliverdin and accumulate it in the skeleton, while red corals and other Octocorallia species cannot. Further information from molecular studies of H. coerulea will provide insights into the synthesis of biliverdin IXα, the blue pigment in the hard crystalline aragonite skeleton, and will be fundamental to future ecological and physiological studies.

Integrated evidence reveals a new species in the ancient blue coral genus Heliopora (Octocorallia)

“…Biliverdin IXa is formed by the oxidative stress-inducible proteinheme oxygenase (HO) during heme decomposition 24 . A metatranscriptome analysis has confirmed the functional genes for heme synthesis are present in both Heliopora coerulea and its photosynthesizing symbiont 25 . However, the final part of the heme synthesis pathway, which converts biliverdin IXa to bilirubin via biliverdin reductase, was not identified.…”

“…Considering the unique role that the symbiont plays in the c5 pathway leading to heme synthesis 25 , we also examined if there were any differences in symbiont species/lineages between H. coerulea and H . hiberniana sp.…”

Marine natural products

“…Culture in the presence of cobalt induced production of antibiotic polyenes 538-541. 224 Other Penicillium strains produced indole diterpenoids 542- 238 Culture of Scedosporium apiospermum on media supplemented with various amino acids induced production of a range of alkaloids including scedapins A-G (599-605) and scequinadolines A-G (606)(607)(608)(609)(610)(611)(612). Of these, scedapin C 601 and scequinadoline D 609 displayed signicant activity against hepatitis C virus (HCV).…”

“…Exposure of juvenile and adult coral Acropora millepora to hyposaline conditions led to increased dimethylsulfoniopropionate (DMSP) levels and upregulation of candidate genes associated with production of DMSP via an alga-like pathway. 608 The genes associated with biosynthesis of the blue pigment biliverdin IXa present in the blue coral Heliopora coerulea have been identied, 609 and furanosesquiterpenes from the Mediterranean so coral Maasella edwardsi can act simultaneously as toxins, inducers of avoidancelearning and as aposematic odorant cues. 610…”

Gene expression profiling reveals deep‐sea coral response to the Deepwater Horizon oil spill

“…This study provides the first published transcriptomic data set for a deep‐sea octocoral. While published RNAseq data exists for approximately nine (Burge et al., ; Fuess, Mann, Jinks, Brinkhuis, & Mydlarz, ; Hongo, Yasuda, & NagaI, ; Pratlong et al., ,; Romiguier et al., ; Zapata et al., ) of an estimated 3,000 octocoral species (Daly et al., ), the three published deep‐sea coral transcriptomes to date are from distantly related calcifying, scleractinian corals from the Red Sea (Yum et al., ), with divergence estimates of approximately 600 MYA (Kumar, Stecher, Suleski, & Hedges, ). As the genus Paramuricea is widespread and has been impacted by several different types of anthropogenic stressors at a variety of depths (Cerrano et al., ; Coma, Pola, Ribes, & Zabala, ), this transcriptome will be useful in future investigations of anthropogenic impacts on corals and other invertebrates as the human influence on the deep sea expands and evolves.…”