Autosomal polymorphism in laboratory bred and wild Norway rats, Rattus norvegicus, found in Misima

Zearalenone induces chromosome aberrations in mouse bone marrow: preventive effect of 17beta-estradiol, progesterone and Vitamin E

The cytogenetic effect of zearalenone (ZEN), a non-steroidal estrogenic mycotoxin, was evaluated in vivo, in mouse bone marrow cells, by assessing the percentage of cells bearing different chromosome aberrations. The studies included different conditions for animal treatment, as follows: (1) single intraperitoneal (ip) injection, (2) repeated ip injections, (3) pre-treatment for 24h with Vitamin E (Vit E), and (4) pre-treatment for 4h with 17beta-estradiol (17beta-Est) or progesterone (Prog). ZEN induced different types of chromosome aberrations, which was concentration-dependent (2-20 mg/kg bw). These doses corresponded to 0.4-4% of the LD50 in the mouse. Interestingly, when the dose of ZEN (40 mg/kg) was fractionated into four equivalent doses (4 x 10 mg/kg bw), into three doses (15 + 10 + 15 mg/kg bw), or into two equivalent doses (2 x 20 mg/kg bw), given every 24 h, the percentage of chromosome aberrations increased significantly. This finding suggests that ZEN proceeds by reversible binding on receptors that could become saturated, and that it damages the chromosomes in a 'hit and go' manner. Furthermore, pre-treatment of animals with 17beta-estradiol or progesterone significantly decreased the percentage of chromosome aberrations, suggesting that (i) these hormones bind to the same cytoplasmic receptors transported into the nucleus to elicit DNA damage, (ii) they may play a role in preventing chromosome aberrations induced by ZEN. Similarly, Vit E prevented these chromosome aberrations indicating that Vit E, previously reported to prevent most of the toxic effects induced by ZEN, may also bind to the same receptors.

Evaluation of genotoxic potential of synthetic progestin chlormadinone acetate

The genotoxicity study of a synthetic progestin chlormadinone acetate, was carried out on mouse bone marrow cells using sister chromatid exchanges (SCEs) and chromosomal aberrations (CAs) as parameter, chlormadinone acetate was studied at three different doses, i.e. 5.62, 11.25 and 22.50 mg/kg body weight and was found to be non-genotoxic at 5.62 mg/kg body weight. But at 11.25 and 22.50 mg/kg of body weight chlormadinone acetate increases SCE (P < 0.001) and CA (P < 0.01) at significant level compared to normal control. The results suggests a genotoxic and cytotoxic effect of chlormadinone acetate in mouse bone marrow cells.

In vivo antimutagenic effect of vitamins C and E against rifampicin-induced chromosome aberrations in mouse bone-marrow cells

-The genotoxic effect of rifampicin (RMP), one of the most active antituberculosis agents is studied. Also, the possible protection provided by the natural antioxidant vitamins C (VC) and E (VE) against the genotoxic effect of RMP is assessed. Mice were orally treated by gavage with 10, 50, 150 and 300 mg RMP kg(-1) body weight (bw). Also, oral treatment was conducted with RMP plus the vitamins. Mice received 300 mg RMP kg(-1) bw plus 100, 200 and 400mg VC or VE kg(-1) bw. Samples were taken 24h after the treatment. Repeated treatments with: (1) the therapeutic dose of RMP (10 mg kg(-1) bw); (2) RMP plus a dose of 25, 50 and 75 mg VC kg(-1); (3) RMP plus 10, 20 and 40 mg VE kg(-1) bw for 30 consecutive days were conducted. The tested doses of RMP induced a significant increase in the percentage of chromosome aberrations. However, a lower percentage of chromosome aberrations was observed when animals were treated with the therapeutic dose for 30 consecutive days. The obtained results revealed that chromosome aberrations induced by RMP decreased to a significant extent when mice were treated with RMP plus VC. The repeated doses of VC reduced the percentage of chromosome aberrations induced by RMP in a significant and dose-dependent manner. On the other hand, repeated doses of VE were not very effective in reducing the percentage of chromosome aberrations induced by RMP. Only the highest dose (3 x 40 mg kg(-1) bw) showed a significant effect (P<0.01). The results on the induction of chromosome damage clearly show that only VC appears able to efficiently protect the bone-marrow cells when given together with RMP, while no significant reduction in the yield of chromosome aberrations was observed for VE in combination with the antituberculosis drug.

The protective role of thiola and soybean seeds against the genotoxicity induced by potassium dichromate in mice

The genotoxic potential of potassium dichromate (K(2)Cr(2)O(7)) was evaluated in vivo in mice using different mutagenic end points. Chromosomal aberrations in bone-marrow and spermatocytes as well as sperm abnormalities in the tested mice were determined. The doses used were 3, 6, 12 mg K(2)Cr(2)O(7)kg(-1) body weight which correspond to 1/16, 1/8, 1/4 the experimental LD(50), respectively. The protective roles of i.p. injection with thiola (a synthetic sulfhydryl compound) at 20 mg kg(-1) body weight and feeding treatment with soybean seeds (30% of the diet) were also studied. For chromosomal aberration analysis, subacute treatment for a period of 3 weeks were performed. All the tested doses of K(2)Cr(2)O(7) induced a statistically significant increase in the percentage of chromosomal aberrations in both somatic and germ cells with dose and time relationships. The percentage of the induced chromosomal aberrations was significantly minimized in all groups of mice i.p. treated with thiola or fed soybean seeds during the period of treatment. Potassium dichromate also induced a significant increase (P<0.01) in the percentage of abnormal sperms at the doses 6 and 12 mg kg(-1) body weight. Such percentage reached 7.52+/-0.45, 5.50+/-0.53 and 4.28+/-0.45 in mice treated with the highest tested dose of K(2)Cr(2)O(7), K(2)Cr(2)O(7) and thiola; K(2)Cr(2)O(7) and soybean, respectively compared with 2.14+/-0.33 for the control. In conclusion, the results demonstrate the genotoxic effect of potassium dichromate in mice. The results also confirm the protective role of thiola and soybean seeds against the genotoxicity of potassium dichromate.

Cytogenetic studies on Nigella sativa seeds extract and thymoquinone on mouse cells infected with schistosomiasis using karyotyping

The protective effect of Nigella sativa seed extract and its main constituents thymoquinone (TQ) was studied on mouse cells infected with schistosomiasis. Bone marrow cells in the in vivo experiments and spleen cells in the in vitro one were used to evaluate the potentially protective effect of these natural compounds on the induction of chromosomal aberrations. Karyotyping of the mice cells illustrated that the main abnormalities were gaps, fragments and deletions especially in chromosomes 2, 6 and some in chromosomes 13 and 14. Both N. sativa extract and TQ were considered as protective agents against the chromosomal aberrations induced as a result of schistosomiasis.

Cytogenetic studies on the effect of feeding mice with stored wheat grains treated with malathion

The cytogenetic effect of malathion residues in wheat grains stored for different periods of time (4, 12, 24 weeks) was evaluated in Swiss mice. The studies included: (1) chromosomal aberrations analysis in bone-marrow and spermatocyte cells; (2) chromosomal aberrations and sister chromatid exchange (SCE) analysis in spleen cell culture from mice fed with stored wheat grains. The tested doses were 8.36 (applied dose), 25.08 and 41.80 mg malathion kg(-1) wheat grains. The results demonstrated that the cytogenetic effect induced in different mouse tissues by malathion residues was dose-dependent and increased with increasing of both feeding and storage periods. Feeding mice with wheat grains stored for 4 weeks had a non-significant effect with respect to the induction of chromosomal aberrations or SCEs. Significant chromosome damage and increase of SCEs were observed in mice fed with wheat grains stored for 12 weeks. The maximum effect was recorded in mice fed for 12 weeks with the grains treated with the highest tested dose and stored for 24 weeks. However, mitomycin C i.p.-injected in mice at 1 mg kg(-1) body weight (b.w.) (positive control) induced a higher effect. The percentage of chromosome aberrations reached 13.60+/-0.98, 13.60+/-0.77 and 11.73+/-0.98 (P<0.01) in bone-marrow, cultured spleen cells and spermatocytes, respectively. The significant increase of abnormalities in spermatocytes was seen for univalent formation only, predominantly of the sex chromosomes. The frequency of SCEs was 10.76+/-0.62 per cell (P<0.01) in cultured spleen cells compared with 5.46+/-0.45 per cell for control and 14.66+/-0.54 per cell for the positive control. The obtained results indicate that malathion residues in stored wheat grains have potential genotoxic effect in mice under the conditions tested.

Genotoxic effect of 2,4-dichlorophenoxy acetic acid and its metabolite 2,4-dichlorophenol in mouse

The cytogenetic effect of 2,4-dichlorophenoxy acetic acid (2,4-D) and its metabolite 2,4-dichlorophenol (2,4-DCP) was studied in bone-marrow, germ cells and sperm head abnormalities in the treated mice. Swiss mice were treated orally by gavage with 2,4-D at 1.7, 3.3 and 33 mg kg(-1)BW (1/200, 1/100 and 1/10 of LD(50)). 2,4-DCP was intraperitoneally (i.p.) injected at 36, 72 and 180 mg kg(-1)BW (1/10, 1/5, 1/2 of LD(50)). A significant increase in the percentage of chromosome aberrations in bone-marrow and spermatocyte cells was observed after oral administration of 2,4-D at 3.3 mg kg(-1)BW for three and five consecutive days. This percentage increased and reached 10.8+/-0.87 (P<0.01) in bone-marrow and 9.8+/-0.45 (P<0.01) in spermatocyte cells after oral administration of 2,4-D at 33 mg kg(-1)BW for 24 h. This percentage was, however, lower than that induced in bone-marrow and spermatocyte cells by mitomycin C (positive control). 2,4-D induced a dose-dependent increase in the percentage of sperm head abnormalities. The genotoxic effect of 2,4-DCP is weaker than that of 2,4-D, as indicated by the lower percentage of the induced chromosome aberrations (in bone-marrow and spermatocyte cells) and sperm head abnormalities. Only the highest tested concentration of 2,4-DCP (180 mg kg(-1)BW, 1/2 LD(50)) induced a significant percentage of chromosome aberrations and sperm head abnormalities after i.p. injection. The obtained results indicate that 2,4-D is genotoxic in mice in vivo under the conditions tested. Hence, more care should be given to the application of 2,4-D on edible crops since repeated uses may underlie a health hazard.

In vivo and in vitro studies on the genotoxicity of cadmium chloride in mice

The genotoxic effect of cadmium chloride was evaluated in chromosomes of experimental mice using in vivo and in vitro studies. In vivo the induction of micronuclei, sister chromatid exchange in mouse bone marrow and chromosomal aberrations in both somatic and germ cells was investigated. Doses 1.9, 5.7 and 7.6 mg kg(-1) body wt. (single i.p. treatment) induced a significant and dose-dependent increase in the percentage of polychromatic erythrocytes with micronuclei. Such a percentage reached 2.1% with the highest tested dose, compared with 0.57% for the control (non-treated) and 2.2% for mitomycin c as the positive control. The dose of 1.9 mg kg(-1) body wt. had no significant effect with respect to sister chromatid exchange (SCE) but the doses of 5.7 and 7.6 mg kg(-1)body wt. increased the frequency of SCEs significantly. The frequency of SCE reached 7.35 +/- 0.26 per cell after treatment with the highest tested dose, which is a less than twofold increase compared with the control frequency of 4.6 +/- 0.42 per cell. However mitomycin c induced a much higher effect (12.1 +/- 0.73). Cadmium chloride also induced a significant increase in the percentage of chromosomal aberrations in mouse bone marrow at the doses of 5.7 and 9.5 mg kg(-1) body wt. (single i.p. treatment). The effect is a function of cadmium chloride concentration. Moreover, cadmium chloride induced its maximum effect concerning the induction of chromosomal aberrations in mouse bone marrow cells 24 h after treatment, compared with 12 and 48 h. In germ cells, chromosomal aberrations were observed in mouse spermatocytes 12 days post-treatment with the dose of 5.7 mg kg(-1) body wt. Moreover, a pronounced reduction in the number of spermatocytes was observed after administration of cadmium chloride (0.9, 1.9 and 5.7 mg kg(-1) body wt.) In in vitro studies, the three tested concentrations of 10, 15 and 20 microgram ml(-1) cadmium chloride induced a statistically significant increase in the frequency of SCEs in cultured mouse spleen cells. The concentrations of 15 and 20 microgram ml(-1) also induced chromosomal aberrations in mouse spleen culture. The ability of vitamin C (l-ascorbic acid) to minimize the incidence of chromosomal aberrations induced by cadmium chloride in cultured mouse spleen cells was investigated. Vitamin C at the concentrations of 3 and 6 microgram ml(-1) significantly minimized the percentage of aberrant cells induced by cadmium chloride.

Mutagenicity of the mycotoxin diacetoxyscirpenol on somatic and germ cells of mice

Genotoxicity of diacetoxyscirpenol (DAS) was studied on laboratory mice after intraperitoneal injection with single and repeated doses. DAS was administrated at three different dose levels (0.5, 0.75, and 1.0 mg/kg body weight). The study was conducted on both somatic and germ cells additional to the sperm morphology analysis. DAS treatment resulted in a significant reduction (P<0.01) in mitotic activity at all levels of doses tested, confirming that DAS is a potent protein and DNA synthesis inhibitor. At somatic cells (bone marrow) both structural and numerical chromosome abnormalities were observed. Single dose treatment showed significant abnormalities only with high dose treatment. In contrast, at repeated dose similar abnormalities were also observed with some significance but no systematic relation between the administrated dose and abnormalities ratio could be settled. In germ cells (testicles), structural and numerical abnormalities were also observed. In general, the frequencies of scored abnormalities at germ cells were lower than that the somatic cells. Sperm count test revealed a decrease in the number of released sperm after toxin treatment. Abnormalities of sperm shape (head and tail) were observed, confirming the positive correlation between cytogenetic damage and sperm abnormality.The results also proved that DAS is a very toxic mycotoxin, in addition to inducing chromosomal abnormalities, it causes a severe inhibition of DNA synthesis which subsequently affects the cell cycle and cell division. A good system for good harvesting practice and good food technology can lower the risk for the consumers.

Induction of chromosomal aberrations and sister chromatid exchange in vivo and in vitro by the insecticide cypermethrin

The induction of chromosomal aberrations and sister chromatid exchange in vivo in mouse spleen and bone marrow as well as in vitro in cultured mouse spleen cells by the insecticide 'Cypermethrin' (cis-trans 1:1) was investigated. The percentage of chromosomal aberrations in the spleen and in the bone marrow as almost the same and reached its maximum 6 h following i.p. injection. The aberrations induced were chromatid and chromosome gaps, fragments and tetraploidy. The insecticide caused a significant and dose-dependent increase in the frequency of sister chromatid exchanges (SCEs) in mouse bone-marrow cells: it reached 11.12 +/- 0.05 per cell after treatment with Cypermethrin at 300 mg kg-1 body wt. compared with 3.7 +/- 0.14 per cell and 4.4 +/- 0.26 per cell in the solvent and control, respectively. The percentage of viable cells in mouse spleen cell cultures reached 87.4% and 99.9% relative to the control after treatment of the cell cultures with 10(-3) and 10(-7) Cypermethrin, respectively. All the tested concentrations of Cypermethrin (0.25-400 micrograms ml-1) induced a high percentage of metaphases with chromosomal aberrations after 4 h of treatment. The mean frequency of SCEs per cell reached 15.1 +/- 0.05 after treatment with Cypermethrin at 4.00 micrograms ml-1 compared with 8.6 +/- 0.23 and 5.9 +/- 0.39 in the solvent and control, respectively. The results indicate that Cypermethrin is genotoxic in mouse spleen and bone marrow as well as in cultured mouse spleen cells.

Clonotypic chromosomal aberrations in long-term lines of myelin-specific rat T lymphocytes

A panel of 16 long-term rat T lymphocyte lines and clones were screened for cytogenetical abnormalities using chromosomal banding techniques. All T lines were CD4+, recognizing the relevant antigen in the molecular context of major histocompatibility complex (MHC) class II determinants. With one exception (an ovalbumin-specific line), all lines were specific for myelin proteins, and apart of one BS rat-derived T line and its clones, all lines were selected from the Lewis strain of rat. After in vitro culture of more than 1 year, all lines and clones exhibited subtle but definite chromosomal aberrations, which included deletions, enlargement, translocations and formation of isochromosomes. All lines were near diploid, structural chromosomal changes being more frequent than numerical abnormalities. Each T line investigated had an individual pattern of chromosomal changes. In our analysis, 16 of the 22 different chromosomes had changes in at least one line. Chromosome 9 and the X chromosome appeared to have an enhanced susceptibility of alterations. In two cases, chromosomal markers could be traced through different stages of in vitro culture of the T lines.

Chromosomal and biochemical studies on the effect of kat extract on laboratory rats

Kat is being used extensively in many countries as a central nervous system stimulant. The effect of three doses of crude kat extract on chromosomal division and abnormalities in bone marrow, as well as on DNA, RNA, and total protein content in brain and liver was studied in laboratory rats in order to test the possible mutagenicity of the drug. Kat was given as a single subcutaneous injection at 0.05 (usage dose), 0.52 (intermediate dose), and 1.00 (sublethal dose) g/kg body weight. Animals were sacrificed at 6, 24, and 48 hr after treatment. Also, some animals were exposed subacutely for 5 consecutive days with sacrifice occurring 6 hr after the last injection. The mitotic index was reduced by all treatments, with the greatest effect occurring in the subacute treatment. Chromosomal abnormalities were induced by kat at all three doses, administered acutely or subacutely. The significant chromosomal aberrations were in the form of gaps, breaks, centromeric attenuations, and centric fusions. The concentration of DNA, RNA, and total protein in liver and brain decreased at all doses, with the greatest decrease occurring after subacute treatment. These findings suggest that kat has a profound effect on cell proliferation, on chromosomal abnormalities, and on DNA, RNA, and total protein synthesis.

Chromosomal aberrations induced by sodium nitrite in bone marrow of adult rats and liver cells of transplacentally exposed embryos

A commonly used food preservative, sodium nitrite, was administered in the drinking water to pregnant (d 5-18 of gestation) and nonpregnant albino rats. Sodium nitrite induced chromosomal aberrations in bone marrow of both pregnant and nonpregnant adults and liver of transplacently exposed embryos. The magnitude of the effect was greater in embryonic liver cells than in adult bone marrow cells.

New inversion of the pair no. 3 chromosome in the black rat

A Japanese black rat (Rattus rattus tanezumi) with a subtelocentric pair no. 3 chromosome was found in Gotenba, Japan. By comparison of the length in both members of the chromosome pair, and from the G-band pattern, the subtelocentrics seemed to have developed from the original acrocentrics by the pericentric inversion.

The location of ribosomal cistrons (rDNA) in chromosomes of the rat

In situ hybridization of 3H-labelled ribosomal RNA to the chromosomes of rat bone marrow cells revealed that clusters of ribosomal cistrons (rDNA) are located in the secondary constrictions of chromosomes No. 3 and 12 and near the centromere of chromosome No. 11, both associated with the late DNA-replicating regions. They were not found in Nos. 1, 2, 13, 19, 20, and the Y chromosome.