The influence of calf thymus DNA and deoxyribonucleosides on the induction of different mutation types in drosophila.

The influence of exogenous DNA on the induction of mutations by X-rays was compared with the influence of an equimolar mixture of four deoxyribonucleosides. Pretreatment and posttreatment with calf thymus DNA did not influence the frequency of mutations at the specific loci dp, b, cn and bw as well as Minute mutations induced in Drosophila sperm by X-radiation. Pretreatment with the equimolar mixture of four deoxyribonucleosides increased the frequency of the Minutes, but it did not affect the frequency of mutations at the loci dp, b, cn, bw. Equimolar mixture of nucleosides alone induced a low frequency of Minute mutations in Drosophila sperm. DNA alone induced a low frequency of recessive lethals. These lethals arose as mosaics of small sectors of the gonads of F1 females and they were revealed as late as the F3 generation.