Disruption of the P450 gene in F. sporotrichioides NRRL 3299. (A) Diagram of the production of inactive copies of the P450 gene as a result of the tandem integration of the disruption vector pIKE4 via a homologous upstream crossover event. Solid boxes, P450 gene promoter region; open boxes, region of the P450 gene present in pIKE4. N, NruI restriction sites. (B) Southern blot analysis of the wild-type (WT) parent NRRL 3299 and P450 gene disruption transformants. Genomic DNA was digested with NruI and probed with a P450 gene fragment prepared by using primers A-74 and A-75. The molecular weight ladder (M) is lambda DNA cut with BstEII. Arrows, band sizes. (C) PCR analysis of F. sporotrichioides NRRL 3299 and transformants. PCRs were conducted with primers A-82 and S-26 (lanes 1) and primers A-82 and A-81 (lanes 2). The primer positions are shown in panel A. PCR products were resolved on an agarose gel and stained with ethidium bromide. The molecular marker (M) is lambda DNA cut with BstEII. Arrows, band sizes.