Variable Rates of Evolution among Drosophila Opsin Genes
AUTOR(ES)
Carulli, J. P.
RESUMO
DNA sequences and chromosomal locations of four Drosophila pseudoobscura opsin genes were compared with those from Drosophila melanogaster, to determine factors that influence the evolution of multigene families. Although the opsin proteins perform the same primary functions, the comparisons reveal a wide range of evolutionary rates. Amino acid identities for the opsins range from 90% for Rh2 to more than 95% for Rh1 and Rh4. Variation in the rate of synonymous site substitution is especially striking: the major opsin, encoded by the Rh1 locus, differs at only 26.1% of synonymous sites between D. pseudoobscura and D. melanogaster, while the other opsin loci differ by as much as 39.2% at synonymous sites. Rh3 and Rh4 have similar levels of synonymous nucleotide substitution but significantly different amounts of amino acid replacement. This decoupling of nucleotide substitution and amino acid replacement suggests that different selective pressures are acting on these similar genes. There is significant heterogeneity in base composition and codon usage bias among the opsin genes in both species, but there are no consistent relationships between these factors and the rate of evolution of the opsins. In addition to exhibiting variation in evolutionary rates, the opsin loci in these species reveal rearrangements of chromosome elements.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1205116Documentos Relacionados
- Elevated Rates of Protein Secretion, Evolution, and Disease Among Tissue-Specific Genes
- Dynamic evolution of plant mitochondrial genomes: Mobile genes and introns and highly variable mutation rates
- Copia Expression Is Variable among Natural Populations of Drosophila
- Molecular Evolution of Drosophila Metallothionein Genes
- Discordant Rates of Chromosome Evolution in the Drosophila Virilis Species Group