title: Unfolding the secrets of coral-algal symbiosis.
abstract: Dinoflagellates from the genus Symbiodinium form a mutualistic symbiotic relationship with reef-building corals. Here we applied massively parallel Illumina sequencing to assess genetic similarity and diversity among four phylogenetically diverse dinoflagellate clades (A, B, C and D) that are commonly associated with corals. We obtained more than 30,000 predicted genes for each Symbiodinium clade, with a majority of the aligned transcripts corresponding to sequence data sets of symbiotic dinoflagellates and <2% of sequences having bacterial or other foreign origin. We report 1053 genes, orthologous among four Symbiodinium clades, that share a high level of sequence identity to known proteins from the SwissProt (SP) database. Approximately 80% of the transcripts aligning to the 1053 SP genes were unique to Symbiodinium species and did not align to other dinoflagellates and unrelated eukaryotic transcriptomes/genomes. Six pathways were common to all four Symbiodinium clades including the phosphatidylinositol signaling system and inositol phosphate metabolism pathways. The list of Symbiodinium transcripts common to all four clades included conserved genes such as heat shock proteins (Hsp70 and Hsp90), calmodulin, actin and tubulin, several ribosomal, photosynthetic and cytochrome genes and chloroplast-based heme-containing cytochrome P450, involved in the biosynthesis of xanthophylls. Antioxidant genes, which are important in stress responses, were also preserved, as were a number of calcium-dependent and calcium/calmodulin-dependent protein kinases that may play a role in the establishment of symbiosis. Our findings disclose new knowledge about the genetic uniqueness of symbiotic dinoflagellates and provide a list of homologous genes important for the foundation of coral-algal symbiosis.
authors.affiliation: School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia.
authors.forename: Nedeljka
authors.initials: N
authors.lastname: Rosic
authors.affiliation: University of Queensland Centre for Clinical Research, The University of Queensland, Herston, Queensland, Australia.
authors.forename: Edmund Yew Siang
authors.initials: EY
authors.lastname: Ling
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, St Lucia, Queensland, Australia.
authors.forename: Chon-Kit Kenneth
authors.initials: CK
authors.lastname: Chan
authors.affiliation: The Kinghorn Cancer Centre, Garvan Institute of Medical Research, Sydney, New South Wales, Australia.
authors.forename: Hong Ching
authors.initials: HC
authors.lastname: Lee
authors.affiliation: 1] School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia [2] Australian Institute of Marine Science, Townsville, Queensland, Australia.
authors.forename: Paulina
authors.initials: P
authors.lastname: Kaniewska
authors.affiliation: 1] School of Agriculture and Food Sciences, The University of Queensland, St Lucia, Queensland, Australia [2] School of Plant Biology, University of Western Australia, Perth, Western Australia, Australia [3] Australian Centre for Plant Functional Genomics, The University of Queensland, St Lucia, Queensland, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Edwards
authors.affiliation: 1] School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia [2] ARC Centre of Excellence for Coral Reef Studies, The University of Queensland, St Lucia, Queensland, Australia.
authors.forename: Sophie
authors.initials: S
authors.lastname: Dove
authors.affiliation: 1] School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia [2] ARC Centre of Excellence for Coral Reef Studies, The University of Queensland, St Lucia, Queensland, Australia [3] Global Change Institute and ARC Centre of Excellence for Coral Reef Studies, The University of Queensland, St Lucia, Queensland, Australia.
authors.forename: Ove
authors.initials: O
authors.lastname: Hoegh-Guldberg
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D057894:Coral Reefs; D004141:Dinoflagellida / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D018503:Genome, Protozoan; D010802:Phylogeny; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D013559:Symbiosis; D059467:Transcriptome
chemical_list: D015800:Protozoan Proteins