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Journal of Molecular Evolution

, Volume 47, Issue 6, pp 697–708 | Cite as

Sequence Analysis of the Mitochondrial Genome of Sarcophyton glaucum: Conserved Gene Order Among Octocorals

  • Margaret J.  Beaton
  • Andrew J.  Roger
  • Thomas  Cavalier-Smith

Abstract.

The nucleotide sequence for an 11,715-bp segment of the mitochondrial genome of the octocoral Sarcophyton glaucum is presented, completing the analysis of the entire genome for this anthozoan member of the phylum Cnidaria. The genome contained the same 13 protein-coding and 2 ribosomal RNA genes as in other animals. However, it also included an unusual mismatch repair gene homologue reported previously and codes for only a single tRNA gene. Intermediate in length compared to two other cnidarians (17,443 and 18,911 bp), this organellar genome contained the smallest amount of noncoding DNA (428, compared to 1283 and 781 nt, respectively), making it the most compact one found for the phylum to date. The mitochondrial genes of S. glaucum exhibited an identical arrangement to that found in another octocoral, Renilla kolikeri, with five protein-coding genes in the same order as has been found in insect and vertebrate mitochondrial genomes. Although gene order appears to be highly conserved among octocorals, compared to the hexacoral, Metridium senile, few similarities were found. Like other metazoan mitochondrial genomes, the A + T composition was elevated and a general bias against codons ending in G or C was observed. However, an exception to this was the infrequent use of TGA compared to TGG to code for tryptophan. This divergent codon bias is unusual but appears to be a conserved feature among two rather distantly related anthozoans.

Key words:Sarcophyton glaucum— Cnidaria — Mitochondrial DNA — Nucleotide sequence — Genetic code — Gene order 

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Copyright information

© Springer-Verlag New York Inc. 1998

Authors and Affiliations

  • Margaret J.  Beaton
    • 1
  • Andrew J.  Roger
    • 2
  • Thomas  Cavalier-Smith
    • 1
  1. 1.Evolutionary Biology Program, Canadian Institute for Advanced Research, Department of Botany, University of British Columbia, Vancouver B.C., Canada V6T 1Z4CA
  2. 2.Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USAUS

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