ARTICLE IN PRESS

A DNA methyl-binding column was used to isolate genomic fragments enriched for DNA-methylation from Aspergillus parasiticus. One of the isolated sequences presented 67 % identity at the protein level with the transposase from the transposable element Tan1 of Aspergillus niger var. awamori, and was found to be present in at least 20 copies in the Aspergillus oryzae database. Analysis of four copies showed evidence of C:G to T:A transitions in at least 98.2 % of the mutations found over a 1032–1180 bp region spanning a large part of the transposase sequence. Using copy speciWc primers three sequences were ampliWed from a diVerent strain of A. oryzae and a similar pattern of C:G to T:A transitions was found. These transitions are similar to those observed in RIP, in Neurospora crassa, where cytosine-methylation is believed to be involved. Using methylation-sensitive Southern blotting, no evidence of methylation was found in the trans-posase sequences in these two A. oryzae strains as well as one A. parasiticus and one Aspergillus Xavus strain