Phylogenetic tree of ureohydrolases. For construction of the tree, selected sequences from eubacteria, fungi, plants, and animals were used in addition to the cyanobacterial sequences given (Tables 3 and 4). For details on the non-cyanobacterial sequences see Sekowska et al.  and Chen et al. . Details on the cyanobacterial sequences are given (Tables 5, 6, and 9).