Inhibitors of thymidylate synthesis increase whereas thymidine decreases meiotic recombination in Drosophila melanogaster.

We have demonstrated the effect of different media on meiotic recombination in Drosophila melanogaster. Recombination is more frequent when the medium is deprived of bases, nucleosides and nucleotides. We have shown that two inhibitors of thymidylate (dTMP) synthesis - aminopterin inhibiting dihydrofolate reductase (DHFR) and fluorodeoxyuridine (FUdR) inhibiting thymidylate synthetase - result in a significant increase in meiotic recombination in the yellow/white region on the X chromosome of Drosophila melanogaster. Moreover the addition of thymidine to the richest medium significantly lowers normal recombination. Such studies represent a powerful tool for future studies on the mechanism of meiotic recombination.