The genome of the lepidopteran Mamestra brassicae has a vertebrate-like content of methyl-cytosine

Mamestra brassicae genomic DNAs, isolated from larvae and adult tissues and from in vitro cultured CRL-8003 cells, were enzymatically hydrolysed to nucleosides that were separated by HPLC. HPLC analysis showed that 5mC content in cabbage moth larvae, adults and cultured cells was 8.9 +/- 0.5, 9.3% +/- 0.2 and 10.2% +/- 0.4 respectively. Cabbage moth 5mC content results the highest reported till now in insects and it is similar to the typical vertebrate one. Analysis of MspI and HpaII restriction pattern on M. brassicae DNA showed that a portion of its genome was methylated at CpG sites. Moreover, the absence of small digestion products after MspI digestion suggested that CpG are not clustered in the cabbage moth genome. Finally, methylation of repeated DNAs has been studied. Comparison of the restriction pattern of MspI and HpaII after hybridisation with the hobo, mariner, 28S and 5S rDNA probes did not evidence any difference indicating the absence of CpG methylation in all the studied repeated DNAs.