Localising a promoter amongst cassettes 16-21 of the Vibrio sp. DAT722 array. A series of PCRs using ORF-specific primers are designed to produce the products shown in the centre of the figure. Results on the right of the figure, showed that no detectable cDNA species included binding sites for both primers VhC19f and VhC21r. This indicated the presence of a promoter between these locations. Further localisation of this promoter is detailed in Figure 8.