DNA of Drosophila melanogaster contains 5-methylcytosine

It is commonly accepted that the DNA of Drosophila melanogaster does not co ntain 5-methylcytosine, which is essential in the development of most eukar yotes. We have developed a new, highly specific and sensitive assay to dete ct the presence of 5-methylcytosine in genomic DNA. The DNA is degraded to nucleosides, 5-methylcytosine purified by HPLC and, for detection by 1D- an d 2D-TLC, radiolabeled using deoxynucleoside kinase and [gamma-P-32]ATP. Us ing this assay, we show here that 5-methylcytosine occurs in the DNA of D.m elanogaster at a level of similar to1 in 1000-2000 cytosine residues in adu lt flies. DNA methylation is detectable in all stages of D.melanogaster dev elopment.