FIG 2.

Spectrum of pyrE mutations in Δogg Δdbh S. acidocaldarius. Each of 103 independent mutations inactivating the native pyrE gene of strain RJ803 is depicted above the corresponding position of the wild-type sequence. Duplication of an existing base pair is indicated by “+,” whereas a single-base deletion as indicated by “Δ”; tracts of the same base pair are overlined to indicate that they behave as a single point with respect to + or Δ events. A 26-bp interval tandemly duplicated in one mutant is overlined, and a 16-bp interval deleted from one mutant is underlined.