The number of distinct functional classes of single-stranded RNAs (ssRNAs) and the number of sequences representing them are substantial and continue to increase. Organizing this data in an evolutionary context is essential, yet traditional comparative sequence analyses require that homologous...

Like proteins, single-stranded RNA's (ssRNAs) undergo intramolecular folding into complex conformations which determine their metabolic function. We have compiled nucleotide composition data, expressed as G+A and G+U in addition to G+C content, from phylogenetically representative samples of...