Nucleotide sequence and evolution of coding and noncoding regions of a quail mitochondrial genome |
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Authors: | Paul Desjardins Réjean Morais |
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Institution: | (1) Départment de biochimie, Faculté de médecine, Université de Montréal, C.P. 6128, Succ. A, H3C 3J7 Montréal, Québec, Canada;(2) Present address: Institute for Molecular Biology and Biotechnology, McMaster University, L8S 4K1 Hamilton, Ontario, Canada |
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Abstract: | Summary Segments of the Japanese quail mito-chondrial genome encompassing many tRNA and protein genes, the small and part of the large
rRNA genes, and the control region have been cloned and sequenced. Analysis of the relative position of these genes confirmed
that the tRNAGlu and ND6 genes in galliform mitochondrial DNA are located immediately adjacent to the control region of the molecule instead
of between the cytochrome b and ND5 genes as in other vertebrates. Japanese quail and chicken display another distinctive
characteristic, that is, they both lack an equivalent to the light-strand replication origin found between the tRNACys and tRNAAsn genes in all vertebrate mitochondrial genomes sequenced thus far. Comparison of the protein-encoding genes revealed that
a great proportion of the substitutions are silent and involve mainly transitions. This bias toward transitions also occurs
in the tRNA and rRNA genes but is not observed in the control region where transversions account for many of the substitutions.
Sequence alignment indicated that the two avian control regions evolve mainly through base substitutions but are also characterized
by the occurrence of a 57-bp deletion/addition event at their 5′ end. The overall sequence divergence between the two gallinaceous
birds suggests that avian mitochondrial genomes evolve at a similar rate to other vertebrate mitochondrial DNAs. |
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Keywords: | Coturnix japonica Mitochondrial DNA Mitochondrial genes Gene rearrangements Nucleotide substitutions Evolution |
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