Complete nucleotide sequence of the mitochondrial genome of a salamander, Mertensiella luschani.
The complete nucleotide sequence (16,650 bp) of the mitochondrial genome of the salamander Mertensiella luschani (Caudata, Amphibia) was determined. This molecule conforms to the consensus vertebrate mitochondrial gene order. However, it is characterized by a long non-coding intervening sequence with two 124-bp repeats between the tRNA(Thr) and tRNA(Pro) genes. The new sequence data were used to reconstruct a phylogeny of jawed vertebrates. Phylogenetic analyses of all mitochondrial protein-coding genes at the amino acid level recovered a robust vertebrate tree in which lungfishes are the closest living relatives of tetrapods, salamanders and frogs are grouped together to the exclusion of caecilians (the Batrachia hypothesis) in a monophyletic amphibian clade, turtles show diapsid affinities and are placed as sister group of crocodiles+birds, and the marsupials are grouped together with monotremes and basal to placental mammals. The deduced phylogeny was used to characterize the molecular evolution of vertebrate mitochondrial proteins. Amino acid frequencies were analyzed across the main lineages of jawed vertebrates, and leucine and cysteine were found to be the most and least abundant amino acids in mitochondrial proteins, respectively. Patterns of amino acid replacements were conserved among vertebrates. Overall, cartilaginous fishes showed the least variation in amino acid frequencies and replacements. Constancy of rates of evolution among the main lineages of jawed vertebrates was rejected.
Zardoya
Rafael
R
Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal, 2, 28006 Madrid, Spain. rafaz@mncn.csic.es
Malaga-Trillo
Edward
E
Veith
Michael
M
Meyer
Axel
A
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010802:Phylogeny; D012455:Salamandridae / Q000235:genetics*; D017422:Sequence Analysis, DNA; D014714:Vertebrates / Q000235:genetics
D004272:DNA, Mitochondrial