TAXONOMY OF 5-S RIBOSOMAL-RNA BY THE LINGUISTIC TECHNIQUE - PROBING WITH MITOCHONDRIAL AND MAMMALIAN SEQUENCES

Linguistic similarities and dissimilarities between 5 S rRNA sequences allowed taxonomical separation of species and classes. Comparisons wi th the molecule from mammals distinguished fungi and plants from proti sts and animals. Similarities to mammalians progressively increased fr om protists to invertebrates and to somatic-type molecules of the vert ebrates lineage. In this, deviations were detected in avian, oocyte ty pe, and pseudogene sequences, Among bacteria, actinobacteria were most similar to the mammalians, which could be related to the high frequen cy of associations among members of these groups. Some archaebacterial species most similar to the mammalians belonged to the Thermoproteale s and Halobacteria groups, Comparisons with the soybean mitochondrial molecule revealed high internal homogeneity among plant mitochondria. The eubacterial groups most similar to it were Thermus and Rhodobacter ia gamma-1 and alpha-2. Other procedures have already indicated simila rities of Rhodobacteria alpha to mitochondria but the linguistic simil arities were on the average higher with the first two groups.