Morphogenic effects of halogenated thymidine analogs on Drosophila. II. Incorporation of 5 -bromodeoxyuridine into DNA.

When 5-bromodeoxyuridine is fed to Drosophila larvae, a variety of morphogenic lesions are found in the hatching adults. Experiments were undertaken to determine whether 5-bromodeoxyuridine is incorporated into Drosophila DNA under the conditions which induce developmental modifications. Radioautographic techniques were used to examine the distribution of [aH lbromodeoxyuridine in Drosophila larvae. Label was found in nuclei of the larval tissues and the imaginal disc cells as well as the gonads. DNA was isolated from Drosophila larvae which were fed 5-bromodeoxyuridine alone or in the presence of a thymidylate inhibitor, and these samples were examined by CsC1 equilibrium density-gradient centrifugation. In the presence of 5-fluorouracil the amount of 5-bromodeoxyuridine incorporated into Drosophila DNA was increased, and this difference was reflected as a relative increase in the denser component of BUdR-DNA in CsC1 density gradients.