MODIFICATION OF PREMUTATIONAL RADIATION DAMAGE IN DROSOPHILA

Journal Article · Mon Jan 01 04:00:00 EST 1962 · Strahlentherapie, Sonderbaende

OSTI ID:4645014

Sobels, F H

Previous studies showed that post-treatment with cyanide results in a significant increase of the frequency of sex-linked lethals after exposure of male flies to x rays given at a high dose rate. The effect is restricted to stages with peak sensitivity to radiation, presumably corresponding to spermatids and possibly late spermatocytes. Data from combined lethal and translocation experiments and the finding that post-treatment also enhances the mutation rate in a ring-shaped X chromosome provided independent evidence that the increase in lethal frequency due to cyanide involves gene mutations and possibly small delections. Further studies were conducted on changes of radioinduced mutation frequencies in successive stages of Drosophila spermatogenesis after post- treatment with both HCN and N/sub 2/, after dose fractionation, and after pretreatment with both chloramphenicol and ribonuclease. Except for the latter experiments all exposures were given at the high dose rate of 45 r or 55 r/sec. Post-treatment with cyanide may lead to either an increase or a decrease of the mutation rate in stages with peak sensitivity. Post-treatment with purified N/ sub 2/ increases the mutation frequency in spermatids, meiotic stages, and spermatogonia. Fractionation of the dose lowers the mutagenic effect of radiation in stages with peak sensitivity. In addition to this effect, dose fractionation followed by post-treatment with N/sub 2/ reduces the mutation frequency in spermatogonia. Pretreatment with chloramphenicol decreases the mutation frequency in spermatids, spermatocytes, and late spermatogonia, whereas an increase was observed in mature sperm. Pretreatment with ribonuclease likewise results in raising the radiation-induced mutation frequency in mature sperm and in lowering that in spermatids. It is concluded that in Drosophila males, modification of premutational damage is possible in spermatids, meiotic stages, and perhaps in spermatogonia. It appears that, as in paramecium, two contrasting processes are involved, one being associated with the rate of disappearance of premutational damage, the other with the rate required for its fixation to mutation. The observations after pretreatment with chloramphenicol and ribonuclease in sperm and spermatids, suggest that protein synthesis is involved in the different radiosensitivities of these two stages. (BBB)

• Research Organization: State Univ., Leiden
• NSA Number: NSA-17-035567
• OSTI ID: 4645014
• Journal Information: Strahlentherapie, Sonderbaende, Journal Name: Strahlentherapie, Sonderbaende Vol. Vol: 51
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ANIMAL CELLS
ANTIBIOTICS
BIOCHEMISTRY
BIOLOGY AND MEDICINE
CHLORAMPHENICOL
CHROMOSOMES
CYANIDES
DOSE FRACTIONATION
DROSOPHILA
ENZYMES
GONADS
INSECTS
MICROORGANISMS
MITOSIS
MUTATIONS
NITROGEN
PARAMECIA
PROTEINS
RADIATION DOSES
RADIATION INJURIES
RADIOSENSITIVITY
RIBONUCLEIC ACID
RNA- ASE
SEX
X RADIATION