Proteobacterial luxR homolog based phylogenetic tree. The tree was constructed using the Kimura-2-parameter distances in the neighbor joining method. Values near the nodes represent percentage bootstrap support (1000 replicates). Vibrio fischeri Group I [GenBank:M96844, AY292966, AY292967, AY292969, AY292970, AY292979 and AY292980]; and V. fischeri Group II [GenBank:M19039, M25751, M25752, Y00509, AF170104, AY292964, AY292965, AY292971–AY292978, and AY292982–AY292985]. The GenBank accession numbers of the luxRI homologs from Aeromonas are given in Table 1.