Northern analysis of A. nidulans cpcA and histone H4 genes in a culture treated with DTT and in an untreated reference culture. The expression level of the genes was analysed in a culture treated with DTT for 0, 30, 60, 120 and 240 min and in untreated reference culture. The signals of the specific mRNAs were quantified and normalised using the signals of gpd1. The ratio of the signal in the analysed sample vs. the signal in a corresponding reference culture are shown. cpcA , H4 .