Phylogenetic relationships of species harbouring ArgH(A) fusions. A simplified version of the 16S rRNA phylogenetic tree of Alteromonas- and Vibrio-like bacteria reconstructed by Ivanova et al. has been drawn and enriched with the following information. On the right-hand side, available genomic information concerning arg genes; ppc refers to the gene for phosphoenolpyruvate carboxylase, adjacent to argE in many of these organisms; nd: not determined. On the left-hand side, the putative content of the ancestral arg gene clusters are indicated for each deep node of this tree.