Metabolic rate and directional nucleotide substitution in animal mitochondrial DNA |
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Authors: | Martin AP |
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Institution: | Department of Biological Sciences, University of Nevada, Las Vegas 89154-4004, USA. |
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Abstract: | There is marked heterogeneity of nucleotide composition in mitochondrial
DNA across divergent animals. Differences in nucleotide composition
presumably reflect differences in directional nucleotide substitution for
A+T or G+C nucleotides. In mitochondrial DNA, there is A+T directional
nucleotide substitution in most (if not all) animals surveyed, and the
magnitude of directional A+T nucleotide substitution differs greatly within
and among groups. Differences in directional nucleotide substitution among
lineages of mammals can be explained by changes in metabolic physiology.
This relationship is thought to be mediated by the effect of oxygen
radicals because these toxic compounds are by-products of aerobic
metabolism and are known mutagens. Association between metabolism and
nucleotide composition provides additional evidence in favor of the
hypothesis that rates and patterns of nucleotide substitution in
mitochondrial DNA can be influenced by factors that impinge on rates of
endogenous DNA damage.
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