Abstract

In this experiment I intended to reverse a known mutation, dumpy wing mutant (induced by methylmethane sulfonate), of Drosophila melanogaster by injecting the mutant flies with 5-azacyticdine and then observing the "reversal" in the F1 (first offspring) generation. Three concentrations of5-azacytidine: 1.25 mM, 2.5 mM and 5.0 mM were used. Though a complete reversal of wing length was not observed, a partial reversal of the wing, termed "intermediate-wing" was obtained. Some of the progeny also had another mutation of the wing termed "wrinkled-wing." To identify the reversal as a germ line mutation, crosses between certain reversed offspring, that is F1 intercrosses, were also made. To further verify the stability of the germ line F2 intercrosses were also made. The progeny from these crosses inherited the reversed mutation, "intermediate-wing," from their parents. The perpetuation of the reversed mutant trait seems to indicate that the reversed mutations are mutations of the germ line. All these facts lead us to hypothesize that the mutations might have been a result of DNA methylation and the reversed mutants a result of DNA demethylation. The reasons for and the consequences of this hypothesis have also been explored.