DNA from Aspergillus flavus contains 5-methylcytosine

DNA from Aspergillus sp. has been reported not to contain 5-methylcytosine. However, it has been found that Aspergillus nidulans responds to 5-azacyti dine, a drug that is a strong inhibitor of DNA methyltransferases. Therefor e. we have re-examined the occurrence of 5-methylcytosine in DNA from Asper gillus flavus by using a highly sensitive and specific method for detection of modified bases in genomic DNA comprising high-performance liquid chroma tography separation of nucleosides, labeling of the nucleoside with deoxynu cleoside kinase and two-dimensional thin-layer chromatography. Our results show that 5-methylcytosine is present in DNA from A. flavus, We estimate th e relative amounts of 5-methylcytosine to cytosine to be approximately 1/40 0. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.