In vivo genotoxicity of nitrates and nitrites in germ cells of male mice. I. Evidence for gonadal exposure and lack of heritable effects.

Effects of nitrate (doses of 600 and 1200 mg/kg/day during 14 days) and sodium nitrite (60 and 120 mg/kg/day during 14 days) on germ cells of male mice were investigated. The mode of application was stomach intubation. The germ cell stages analysed were spermatids (for the heritable effects) and differentiating and stem-cell spermatogonia (for direct effects). A lack of heritable translocations, sperm abnormalities, as well as morphological changes, such as changes in eyes, coat colour, testes and body weight, was demonstrated in F1 males originating from treated P males. Significant effects in treated males were found with respect to: (1) sex-chromosomal univalency in the diakinesis-methaphase I stage after the treatment of stem spermatogonia (both doses of sodium nitrate and the higher dose of sodium nitrite), (2) sperm-head abnormalities after treatment of differentiating spermatogonia (the higher dose of sodium nitrate and both doses of sodium nitrite), and (3) fertility after treatment of spermatids (the higher dose of sodium nitrite). Nonmutagenic effects and possible carcinogenic potential of the tested doses are discussed.

In vivo genotoxicity of nitrates and nitrites in germ cells of male mice. II. Unscheduled DNA synthesis and sperm abnormality after treatment of spermatids.

Effects of both sodium nitrate (doses of 600 and 1200 mg/kg/day for 3 days) and sodium nitrite (doses of 60 and 120 mg/kg/day for 3 days) on spermatids of mice were investigated by measuring unscheduled DNA synthesis (UDS) 17 days after the end of treatment, and sperm-head abnormality 11 and 17 days after the end of treatment. Neither chemical induced the UDS response in early to mid spermatids (17 days). The only positive result in the sperm-head abnormality test was obtained for the dose of 120 mg/kg/day of sodium nitrite both at 11 and 17 days after treatment. The results presented are in accordance with those of our earlier experiments with the same chemicals, suggesting their nonmutagenic action on the tested germ-cell stages of male mice.

Effect of saccharin on the induction of chromosomal translocations in male mice and their F1 offspring.

The dose-dependent effects of sodium saccharin on the fertility and the induction of chromosomal translocations in treated mice and their F1 males were examined. C3H X 101 mice were treated with saccharin for 2 successive weeks at doses of 200 and 500 mg/kg of body wt. Data from the fertility study showed that saccharin did not induce any significant effect on fertility. Cytological analysis of meiotic cells showed no chromosomal rearrangements. Semisterility and sterility were noted in F1 males of saccharin-treated animals. In semi-sterile and sterile F1 males of saccharin-treated animals chromosomal translocations were not found.

Meiotic chromosomal translocations in male induced by X-irradiation.

The dose-response curve for reciprocal translocations induced by acute exposure of spermatogonial stem cells to X-rays in treated mice and their F-1 sons was examined. Male mice were totally irradiated with doses of 1 Gy; 5 X 1 Gy and 5 Gy. The obtained results show that frequency of the chromosomal translocations in directly treated animals is dose dependent. The percentage of animals irradiated with 1 Gy which had the chromosomal translocations was 60, while this percentage in animals irradiated with single and fractionated dose of 5 Gy was 100. The frequency of chromosomal translocations varies from 1.5% to 8.0%. Multivalent configurations in F-1 males were observed after exposure to 5 Gy only. The incidence of F-1 translocated males was 17.5%.

Effect of oil of nutmeg on the fertility and induction of meiotic chromosome rearrangements in mice and their first generation.

The dose-dependent effects of oil of nutmeg on the fertility and induction of chromosomal translocations in treated mice and their F1 males were examined. C3H male mice were treated with oil of nutmeg for 8 successive weeks at 60, 80, 100 and 400 mg/kg body weight. The greatest reduction of fertility occurred in the group treated with 400 mg/kg; chromosomal translocation in directly treated animals was not found. The chromosomal translocations in F1 males, derived from males treated with oil of nutmeg at dose levels of 60, 80 and 100 mg/kg.

The effect of X-irradiation on the fertility and on the induction of meiotic chromosome rearrangements in mice and their first generation.

The effect of whole-body or local irradiation with X-rays at a dose of 600 R on the induction of chromosomal translocations in the diakinesis metaphase I of the meiosis in treated and F1 males has been examined along with their fertility. Our results show the high percentage of mortality in whole-body irradiated mice. The percentage of the fertility was 25% in whole-body, and 93.7% in locally irradiated males. The testis weight was also reduced. The percentage of chromosomal translocations in diakinesis, metaphase I, or the meiosis was higher after whole-body irradiation than after local irradiation. In F1 males both types of irradiation induced chromosomal translocations.

An analysis of meiotic chromosomes of inbred male mice and their F1 sons after long-term treatment of sires with triethylenemelamine.

The dose-dependent effects of triethylenemelamine (TEM) on fertility and the induction of chromosomal translocation in treated mice and their F1 sons were examined C3H mice were treated with TEM for 8 successive weeks at doses of 0.02 and 0.04 mg/kg of body weight. All males treated with TEM were fertile,and cytological analysis of meiotic cells showed no chromosomal rearrangements. Semi-sterility and sterility were noted in F1 sons of TEM-treated animals. This semi-sterility and sterility were associated with reciprocal translocations. The percentage of animals heterozygous for translocations was higher for F1 males originating from sires treated with TEM at 0.04 mg/kg than from sires treated with 0.02 mg/kg.

The effect of mitomycin on the fertility and the induction of meiotic chromosome rearrangements in mice and their first generation progeny.

The dose dependent effects of chronic application of Mitomycin C(MC) on the induction of chromosomal translocations in treated animals and F1 males and on their fertility have been examined. The C3H strain mice used in the present experiments were treated with MC during eight successive weeks in doses of 0.05 mg/kg and 0.1 mg/kg of body weight. 75 males were treated (25 males per dose and 25 males as controls). Immediately after the chronic treatment they were mated with normal females and were tested for their reproductive performance. The fertility of males was estimated from the number of pregnant females after one week of being together. After that all males were sacrificed and prepared for cytological analysis. No chromosomal translocations were found in diakinesis-metaphase I of meiosis. Data from the study of fertility showed that all treated males were fertile, but all females were not pregnant. The tests of all sterile, semisterile and fertile F1 males showed that F1 males could not be identified as heterozygous translocation carriers.

The effect of erythromycin and its thiocarbamide derivative on the induction of meiotic chromosome rearrangements in irradiated male mice.

Antibiotics, erythromycin and a thiocarbamide derivative of erythromycin were tested for their ability to induce chromosome translocations in whole-body irradiated mice with a dose of 600 r. The aim of the present paper was to determine whether these antibiotics might induce by themselves, chromosomal translocations and whether these agents have a protective effect against X-rays-induced chromosomal translocations in the spermatocytes at the first meiotic metaphase. The incidence of translocations in irradiated animals was 9.07%; in animals treated with erythromycine after irradiation it was 3.80%; and in those treated with a thiocarbamide derivative of erythromycin following irradiation was 3.20%. Not a single chromosome rearrangement was scored among the non-irradiated animals, treated with the mentioned antibiotics.

Cytogenetics analysis of meiotic chromosomes of irradiated mice and their progeny after treatment with streptomycin and dihydrodeoxystreptomycin.

The purpose of this investigation is to find out whether streptomycin and the related compound dihydrodeoxystreptomycin have any mutagenic effect and whether they both are capable of recovering X-ray induced chromosomal translocations in mouse spermatogonia of directly treated animals and their progeny of the first generation. The cytological findings show the absence of any mutagenic effect in animals nonirradiated and treated with streptomycin and dihydrodeoxystreptomycin. The frequency of chromosomal translocation after total irradiation was 9,07%; in animals treated with streptomycin following irradiation 5.13%, and in those irradiated and treated with dihyrodeoxystreptomycin, 3.70%. Male offsprings, originated from parents treated only with antibiotics show no chromosomal translocations. However, offsprings originated from irradiated and treated parents gave birth to the male offspring with chromosomal translocations.