Molecular evolution in papova viruses and their host species, and in bacteriophages : (evolution, nucleotide substitution, papova viruses)

Abstract

Comparing homologous genes of three papova viral genomes, we attempt to show the very close relative phylogeny among the viral species and their host species, and therefore the viral species seem to have evolved with their host organisms (SOEDA et al. 1980). Additionally, the DNA-sequence data of bacteriophages [lowercase phi]X174 and G4 and their overlapping genes will be examined for evolutionary patterns. It will then be made evident that overlapping genes have a quite different substitutional pattern with respect to the position of nucleotides in the codons than do non-overlapping sequences. Namely, in overlapping regions the third positions are usually substituted fastest, followed by the first positions, while the second positions are slowest in each gene, though different genes may have different rates of nucleotide substitution. With overlapping genes, this pattern does not apply, but rather is altered because of an interaction between the substitution rates in the two genes involved in an overlap.