Evolutionary analysis of orthologous cDNA sequences from cultured and symbiotic dinoflagellate symbionts of reef-building corals (Dinophyceae: Symbiodinium)

Voolstra, Christian R., Sunagawa, Shinichi, Schwarz, Jodi A., Coffroth, Mary Alice, Yellowlees, Dave, Leggat, William, and Medina, Monica (2009) Evolutionary analysis of orthologous cDNA sequences from cultured and symbiotic dinoflagellate symbionts of reef-building corals (Dinophyceae: Symbiodinium). Comparative Biochemistry and Physiology Part D: Genomics and Proteomics, 4 (2). pp. 67-74.

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Dinoflagellates are ubiquitous marine and freshwater protists. The endosymbiotic relationship between dinoflagellates of the genus Symbiodinium (also known as zooxanthellae) and corals forms the basis of coral reefs. We constructed and analyzed a cDNA library from a cultured Symbiodinium species clade A (CassKB8). The majority of annotated ESTs from the Symbiodinium sp. CassKB8 library cover metabolic genes. Most of those belong to either carbohydrate or energy metabolism. In addition, components of extracellular signal transduction pathways and genes that play a role in cell–cell communication were identified. In a subsequent analysis, we determined all orthologous cDNA sequences between this library (1,484 unique sequences) and a library from a Symbiodinium species clade C (C3) (3,336 unique sequences) that was isolated directly from its symbiotic host. A set of 115 orthologs were identified between Symbiodinium sp. CassKB8 and Symbiodinium sp. C3. These orthologs were subdivided into three groups that show different characteristics and functions: conserved across eukaryotes (CE), dinoflagellate-specific (DS) and Symbiodinium-specific (SS). Orthologs conserved across eukaryotes are mainly comprised of housekeeping genes, photosynthesis-related transcripts and metabolic proteins, whereas the function for most of the dinoflagellate-specific orthologs remains unknown. A dN/dS analysis identified the highest ratio in a Symbiodinium-specific ortholog and evidence for positive selection in a dinoflagellate-specific gene. Evolution of genes and pathways in different dinoflagellates seems to be affected by different lifestyles, and a symbiotic lifestyle may affect population structure and strength of selection. This study is the first evolutionary comparative analysis of orthologs from two coral dinoflagellate symbionts.

Item ID: 11298
Item Type: Article (Research - C1)
ISSN: 1744-117X
Keywords: cDNA library; Dinoflagellate; ortholog comparison; symbiosis; Zooxanthellae
Date Deposited: 21 May 2010 04:18
FoR Codes: 06 BIOLOGICAL SCIENCES > 0601 Biochemistry and Cell Biology > 060102 Bioinformatics @ 80%
06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060307 Host-Parasite Interactions @ 20%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 100%
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