Southern blot analysis of the Aaku80 -deletion mutants. (a) Restriction enzyme maps of Aaku80 loci in the pyrG13, R1, and MR12 strains of Aspergillus aculeatus. The DNA probe used for Southern blot analysis is indicated with solid bars. N, restriction sites of Nco I. (b) Results of the Southern blot analysis using genomic DNA digested with Nco I (N). Lanes 1, 2, and 3 are pyrG13, R1, and MR12, respectively.