DNA of Drosophila melanogaster contains 5-methylcytosine

It is commonly accepted that the DNA of Drosophila melanogaster does not contain 5-methylcytosine, which is essential in the development of most eukaryotes. We have developed a new, highly specific and sensitive assay to detect the presence of 5-methylcytosine in genomic DNA. The DNA is degraded to nucleosides, 5-methylcytosine purified by HPLC and, for detection by 1D- and 2D-TLC, radiolabeled using deoxynucleoside kinase and gamma-(32)P]ATP. Using this assay, we show here that 5-methylcytosine occurs in the DNA of D. melanogaster at a level of approximately 1 in 1000-2000 cytosine residues in adult flies. DNA methylation is detectable in all stages of D.melanogaster development.