(C) In the absence of thiamine from the growth medium (derepressed conditions) the corresponding strains grow nearly as an isogenic wild-type control, although a delay in growth is observed for thiAp-sedV and less so for thiAp-ap1σ (upper row). In the presence of thiamine to the growth medium most cells do not form colonies, except for thiAp-hypB which forms a compact slow growing colony (lower row). 