Transformation of Aspergillus nidulans with the hygromycin-resistance gene, hph

Aspergillus nidulans strain G191 was transformed to hygromycin resistance using plasmid pDH25, which contains the bacterial hygromycin B phosphotransferase gene (hph) fused to promoter elements of the A. nidulans trpC gene. Southern hybridizations of transformants revealed multiple, integrated copies of the vector. A pleiotropic effect conferring increased hygromycin B sensitivity was found to be associated with the A. nidulans pyrG89 allele. Plasmid pDH25 features a ClaI site immediately preceding the hph start codon thus permitting convenient replacement of the trpC sequences with other eukaryotic promoters.