Phylogenetic tree of arsenite transporters [ArsB/Acr3(1)p/Acr3(2)p]. Phylogenetic analysis of the deduced amino acid sequences (~230 aa) of arsB/ACR3(1)/ACR3(2)genes. Filled triangles, potential horizontally transferred arsenite transporter genes. Sequences in this study are in bold type and bootstrap values over 50% are shown. The scale bar 0.1 shows 10% aa sequence substitution.