FIG. 2.

Vector construction and A. niger transformation. (a) Vector pIB635 for transformation of A. niger strain CBS513.88. This vector contains a synthetic Vader element surrounded by its target site duplication. Vader was cloned between the A. nidulans gpdA promoter and the E. coli hph gene. The 5′ and 3′ flanking sequences from the niaD gene allow homologous recombination into the A. niger niaD sequence. (b) Southern blot hybridization of genomic DNA (lanes 1 to 9) from A. niger transformants selected on chlorate-containing plates and the wild-type (wt) strain CBS513.88 digested with the restriction enzyme XbaI. ³²P[α-dCTP] was used to label the probe. Six transformants were obtained. The arrow indicates transformant AnT-6(3), which was used for all further experiments.