Sequence Analysis of the Mitochondrial Genome of Sarcophyton glaucum: Conserved Gene Order Among Octocorals |
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Authors: | Margaret J Beaton Andrew J Roger Thomas Cavalier-Smith |
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Institution: | (1) Evolutionary Biology Program, Canadian Institute for Advanced Research, Department of Botany, University of British Columbia, Vancouver B.C., Canada V6T 1Z4, CA;(2) Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USA, US |
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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.
Received: 27 January 1998 / Accepted: 25 May 1998 |
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Keywords: | :Sarcophyton glaucum— Cnidaria — Mitochondrial DNA — Nucleotide sequence — Genetic code — Gene order |
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