Effect of antibiotics on the mutagenic activity induced by chemicals. I. Chromosome aberrations during spermatogenesis in mice.

Effect of antibiotics (rifampicin-RIF, puromycin-PU, chloramphenicol-CHF and cycloheximide-CYC) on the frequency of chromosomal abnormalities induced by TEPA [tris (1-aziridinyl) phosphine oxide] was studied by the cytogenetic analysis in mice during spermatogenesis. Males were given intraperitoneally a single dose of one of the following agents: TEPA 1 mg./kg. b.w., RIF 150 mg./kg. b.w., PU 100 mg./kg. b.w., CHF 500 mg./kg. b.w. and CYC 100 mg./kg. b.w., or a simultaneously administered TEPA and an antibiotic. Spermatocytes in the diakinesis/first metaphase stage and in spermatogonia. However, statistically insignificantly increased translocations in the group TEPA-CHF, univalents of X and Y chromosomes in TEPA-CHF, CYC and TEPA-CYC, and the increased frequency of metaphases with 19II + U and 20II + f were induced in the preleptotene stage. The decreased frequency of X and Y univalents in TEPA-RIF and TEPA-CHF was induced in spermatogonia. Results revealed a possible selective pressure against the cells carrying some abnormalities.