Genetic map of ϕX174 including relevant sites regulating gene transcription. Note that the map has been linearized for clarity; ϕX174 has a 5,386 nt circular genome. PA, PB, PD indicate transcription promoters; TJ, TF, TG, TH indicate transcription terminators. A to H indicate genes, and genes B, K and E are in different reading frames from the genes with which they overlap. Bars below the map indicate lengths of transcripts found at 37°C. Based on [10, 13].