FIG. 4.

Effect of gene dosage on pH-dependent growth. (A) The A. fumigatus PMA1 gene was amplified by PCR from wild-type (wt) cells and transformants containing marked copies of PMA1 with a unique EcoRI restriction enzyme site. The fragments were either untreated or digested with EcoRI. The amount of native PMA1 relative to the amount of marked enzyme was used to determine whether cells contained a single copy (1×), double copy (2×), or triple copies (3×) of A. fumigatus PMA1. (B) Approximately 1,000 spores from either wild-type or polyploid PMA1 cells, as described above for panel A, were used to inoculate microdilution medium (YG) containing 50 mM acetate adjusted from pH 3.5 to 7.0. Each assay was performed in duplicate, and growth was determined after 48 h.