FIG. 4.

Phylogenetic tree of eubacteria based on 16s rRNA sequences. The tree contains all the organisms listed in Fig. 3 and was obtained from the Ribosomal Database Project II (30) at its website (38a). The Aquifex sequence comes from Aquifex pyrophilus and not Aquifex aeolicus, because the latter was unavailable. Horizontal branch lengths are drawn to scale; the bar is 0.1 nucleotide replacement per site in length. Species for which homologs of RuvC are absent or yet to be detected are shown in bold type. Abbreviations: Porphyromonas, Porphyromonas gingivalis; Actinobacillus actinomyc., Actinobacillus actinomycetemcomitans.