Fig. 1

Nitrate-inducible aflR/S expression in A. nidulans. a Schematic overview of the aflR/S expression strain TPMW2.3 that harbors the nitrate-inducible niaD/niiA promoter-driven aflR/S genes at the native sterigmatocystin cluster locus. b Northern blot analysis of nitrate-dependent aflR/S expression in A. nidulans TPMW2.3. Strains were grown in 50 mL of GMM with 35 mM glutamine as nitrogen source supplemented with 5 mM uracil/uridine and riboflavin for 24 h at 250 rpm at 37 °C. The mycelia were washed and shifted into new media containing either NH₄⁺ or NO₃⁻ as nitrogen sources plus supplements and grown at 250 rpm and 37 °C for 1 h before RNA extraction. Strains were grown in duplicate, indicated genes were probed and rRNA was visualized as loading control