Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, P.R. China Human de novo DNA methylases Dnmt3a and Dnmt3b were combined with a testis-specific promoter in P element transformation vectors and transformed into Drosophila melanogaster. We recovered 7 or 6 transformant lines, respectively, and investigated the expression of the enzymes. We will report the results on Dnmt3b. The enzyme is expressed in testes as can be demonstrated in Western blots and by immuno-histology. Spermatogenesis was normal in all strains and no effects on fertility were observed. These results are of particular interest as it has recently been shown by Maggert and Golic (2002) that the Y chromosome of Drosophila is subject to imprinting. On the other hand, Weissmann et al. (2003) demonstrated lethality of the Dnmt3a in Drosophila tansformants. Our observations suggest that DNA methylation may be a normal event in the male germ line of Drosophila.
