Abstract
BackgroundMitochondria contain small genomes that are physically separate from those of nuclei. Their comparison serves as a model system for understanding the processes of genome evolution. Although hundreds of these genome sequences have been reported, the taxonomic sampling is highly biased toward vertebrates and arthropods, with many whole phyla remaining unstudied. This is the first description of a complete mitochondrial genome sequence of a representative of the phylum Echiura, that of the fat innkeeper worm, Urechis caupo.ResultsThis mtDNA is 15,113 nts in length and 62% A+T. It contains the 37 genes that are typical for animal mtDNAs in an arrangement somewhat similar to that of annelid worms. All genes are encoded by the same DNA strand which is rich in A and C relative to the opposite strand. Codons ending with the dinucleotide GG are more frequent than would be expected from apparent mutational biases. The largest non-coding region is only 282 nts long, is 71% A+T, and has potential for secondary structures.ConclusionsUrechis caupo mtDNA shares many features with those of the few studied annelids, including the common usage of ATG start codons, unusual among animal mtDNAs, as well as gene arrangements, tRNA structures, and codon usage biases.
Highlights
Mitochondria contain small genomes that are physically separate from those of nuclei
Gene content and organization The mtDNA of Urechis caupo is 15,113 nts in length (GenBank accession number AY619711) and contains the same 37 genes found for most animal mtDNAs [see ref. [1]]
All genes are transcribed from the same strand (Fig. 1), as is the case for the two studied annelid mtDNAs, the polychaete Platynereis dumerilii [6] and the oligochaete Lumbricus terrestris [7] and for several other animal mtDNAs
Summary
Mitochondria contain small genomes that are physically separate from those of nuclei Their comparison serves as a model system for understanding the processes of genome evolution. Hundreds of these genome sequences have been reported, the taxonomic sampling is highly biased toward vertebrates and arthropods, with many whole phyla remaining unstudied. Many of the same processes that occur in large and complex nuclear genomes take place in these diminutive genomes, so comparisons among mtDNAs can address general questions of genome evolution, but in a model system that is much more tractable for a large number of taxa
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.