The Expression of Sterigmatocystin and Penicillin Genes in Aspergillus nidulans Is Controlled by veA, a Gene Required for Sexual Development

Effects of the veA deletion on the transcription of genes implicated in morphological development in A. nidulans. The transcriptional patterns of the developmental genes nsdD, steA, and brlA in the veA⁺ and ΔveA strains were evaluated by Northern analysis. (Left) Total RNAs of the veA⁺ and ΔveA strains were isolated 30, 45, and 60 h after the strains were cultured on solid YGT medium in the dark. rRNA stained with ethidium bromide is shown to indicate RNA loading. (Right) mRNA was quantitated by densitometry and plotted as relative band intensity normalized to rRNA and to the highest band intensity in each graph (considered as 1 U). Two separate repetitions of these experiments yielded similar results.

Combined effects of veA deletion and light on the transcription of genes implicated in morphological and chemical differentiation in A. nidulans. (A) The expression of genes involved in conidiation (brlA) and secondary metabolism (aflR, stcU, and ipnA) was evaluated by Northern analysis in the veA⁺ and ΔveA strains (left). Total RNAs were isolated from the cultures grown on solid YGT medium after 60 h in the light or in the dark. rRNA stained with ethidium bromide is shown to indicate RNA loading. mRNA was quantitated by densitometry and plotted as relative band intensity normalized to rRNA and to the highest band intensity in each graph (considered as 1 U) (right). Two separate repetitions of these experiments yielded similar results. Under the same experimental conditions, other parameters were analyzed as follows. (B) Conidial production per surface area. The values are means of four replicates. (C) ST analysis by TLC. The uncharacterized compound observed in ΔveA near the ST retention factor (R_f) is not ST (in this assay, ST fluoresces bright yellow while the unknown compound fluoresced blue). (D) ST analysis of samples extracted from GMM cultures by TLC. The uncharacterized compound observed in ΔveA near the ST R_f is not ST (in this assay, ST fluoresces bright yellow while the unknown compound fluoresced blue). (E) Effects of the veA deletion on PN production in A. nidulans on solid YGT medium in the light or in the dark. The values are means of four replicates. (F) Detection of acvA expression on YGT medium by RT-PCR. Lanes: 1, veA⁺ in the dark; 2, veA⁺ in the light; 3, ΔveA in the dark; 4, ΔveA in the light; 5, positive control containing genomic DNA as a template; 6, negative control without DNA template; 7 to 10, PCR results of RNA samples (veA⁺ in the dark, veA⁺ in the light, ΔveA in the dark, and ΔveA in the light, respectively) before RT, showing the absence of contaminant genomic DNA in the samples. L, light; D, dark; Std, standard; *, other uncharacterized metabolites absent or present in different amounts in ΔveA with respect to veA⁺. The error bars indicate standard error.

Effects of veA deletion on transcription of genes implicated in production of secondary metabolites during morphological development in A. nidulans. (A) Transcriptional patterns of genes involved in secondary metabolism, aflR and ipnA, were evaluated by Northern analysis in the veA⁺ and ΔveA strains. Total RNAs of the veA⁺ and ΔveA strains were isolated 30, 45, and 60 h after inoculation on solid YGT medium (left). rRNA stained with ethidium bromide is shown to indicate RNA loading. mRNA was quantitated by densitometry and plotted as relative band intensity normalized to rRNA and to the highest band intensity in each graph (considered as 1 U) (right). Two separate repetitions of these experiments yielded similar results. (B) ST analysis by TLC. The uncharacterized compound observed in ΔveA near the ST R_f is not ST (in this assay, ST fluoresces bright yellow while the unknown compound fluoresced blue). Std, standard; *, other uncharacterized metabolites absent or present in different amounts in ΔveA with respect to veA⁺.