Effect of hydroquinone on meiotic segregation in Drosophila melanogaster females

Effects of diesel exhaust-derived secondary organic aerosol (SOA) on oocytes: Potential risks to meiotic maturation

Particulate air pollution (PM 2.5) is a worldwide concern. Growing epidemiological evidence has shown pathophysiological effects of PM 2.5, not only on cardiovascular system but also on reproductive performance. The composition and physicochemical properties of PM 2.5 vary depending on the emission sources, climate conditions, and complex chemical reactions in the air. These factors make it difficult to understand the cause and mechanistic details of the adverse health effects of PM 2.5. Here, we show potential impacts of PM 2.5 on oocyte maturation in mice by utilizing diesel exhaust-derived secondary organic aerosol (SOA), a major component of urban PM 2.5. We found that the SOA destabilized microtubules of mouse oocytes and p-benzoquinone is one of the candidates for the microtubule-destabilizing compounds. We propose that some biologically reactive components of PM 2.5 should be prioritized for the regulation of atmospheric quality.

GSTM1, GSTT1, and GSTP1 polymorphism in north Indian population and its influence on the hydroquinone-induced in vitro genotoxicity

Glutathione S transferase (GST) gene polymorphism examined among north Indians and correlated with hydroquinone (HQ) genotoxicity to help in clinical prediction of susceptibility of HQ toxicity. Lymphocytes of individuals with/without GSTM1, GSTT1, and GSTP1 (ile/ile or val/val) were exposed to HQ (20, 40, or 80 microM) and examined chromosomal aberrations (CA) or cytokinesis-block micronucleus assays. Among north Indians the frequencies of GSTM1 (null), GSTT1 (null), and both null were found to be 41.1, 21.9, and 12.7%, whereas frequencies of GSTP1 with (ile/ile) or (ile/val), or (val/val) were 52, 42.1, or 5.9%, respectively. Individuals with null GSTM1, GSTT1, and GSTP1 (val/val) showed inhibition of mitotic index (MI) and significant (p < 0.01) induction of CA as compared to individuals with GSTM1, GSTT1, and GSTP1 (ile/ile). Micronucleus formation was found to be significant (p < 0.05 or 0.01) in both the genotypes. Results indicate that GSTM1, GSTT1 (null), and GSTP1 (val/val) are sensitive to HQ genotoxicity.

GSTM1, GSTT1, and GSTP1 genotypes and the genotoxicity of hydroquinone in human lymphocytes

Hydroquinone is a myelotoxin that is found in many foods and is also formed through the metabolism of benzene. Human exposure to benzene is associated with the development of myelodysplastic syndrome and acute myelogenous leukemia. Hydroquinone is genotoxic in several in vitro and in vivo test systems, inducing micronuclei (MN), sister-chromatid exchange (SCE), and chromosomal aberrations. Glutathione S-transferases (GSTs) are a superfamily of polymorphic enzymes involved in the conjugation of reactive chemical intermediates to soluble forms. These enzymes play a key role in the detoxification of endogenous and exogenous compounds, and the polymorphic genes GSTM1, GSTT1, and GSTP1 have been associated with the differential metabolism of several genotoxicants. In the present study, we have evaluated the effect of GSTM1, GSTT1, and GSTP1 polymorphisms on the frequency of MN and SCE induced by hydroquinone in human lymphocytes. Lymphocytes were obtained from 15 healthy non-smoking donors, and their GSTM1, GSTT1, and GSTP1 genotypes determined. Treatment of cultures of the lymphocytes with hydroquinone significantly increased the overall frequencies of MN and SCE (P<0.0001). Individuals with the GSTM1 null genotype had a significantly higher frequency of MN compared with GSTM1-present individuals (P=0.013); in contrast, the GSTM1 genotype had no effect on hydroquinone-induced SCE frequency. The other polymorphisms did not significantly affect the frequencies of MN or SCE. These results suggest that GSTM1 is involved in the metabolic fate of hydroquinone and that polymorphisms in GSTM1 could be related to inter-individual differences in DNA damage arising from the exposure to this compound.

Chromosome malsegregation induced by the rodent carcinogens acetamide, pyridine and diethanolamine in Drosophila melanogaster females

The effect of the rodent carcinogens acetamide (AC), pyridine (PY) and diethanolamine (DEA) on meiotic chromosome segregation was assessed in 4-day-old Drosophila melanogaster females. After oral treatment with 0.05, 0.1, 0.2 and 0.3% PY; 0.5, 1, 1.5, 2 and 4% AC; or 5, 10, 20, 40 and 80% DEA, the females were mated to 7-day-old males and three 24h broods were obtained to sample cells exposed mainly as mature oocytes (brood I), and nearly mature oocytes (brood II) with an increasing proportion of early oocytes (brood III). Viability was not affected at the two (PY) or three (AC, DEA) lowest concentrations, decreasing thereafter. PY increased the frequency of nondisjunction exclusively in brood II suggesting its interaction with specific targets. AC and DEA (the most active of the three) induced similar frequencies of nondisjunction in all broods suggesting unspecific cell division perturbations probably due to toxicity. No clear dose effect relationships were observed.

The rodent carcinogens 1,4-dioxane and thiourea induce meiotic non-disjunction in Drosophila melanogaster females

The ability of the rodent carcinogens 1,4-dioxane (DX) and thiourea (TU) to induce meiotic non-disjunction (ND) was assessed in 3- and 6-day-old Drosophila melanogaster females. The chemicals were administered orally and three 24 h and one 48 h broods were obtained after mating, to sample oocytes treated in increasingly earlier stages of development. The broods represent mainly mature oocytes (brood I), nearly mature oocytes (brood II), early oocytes (brood III) and very early oocytes (brood IV). The toxicity of DX increased with dose (1% (not toxic), 1.5, 2, 3, 3.5%) as well as a reduction in fecundity which was moderate. Induction of ND in mature oocytes was positive with 2, 3 and 3.5% concentrations and was not related to dose. In immature oocytes it was also positive though already at the lowest concentration tested (1%), suggesting a sensitivity higher than that of mature oocytes. TU at 0.10-10%, did not affect viability, but since fecundity was seriously impaired at high doses, ND was not assessed beyond the 1.5% concentration. TU also induced ND in mature and in immature oocytes; neither a threshold nor a dose effect was detected. The response of mature oocytes was lower than that of immature oocytes. TU induced increases of ND in the earliest cells tested in a more consistent fashion than DX. The data clearly show that both chemicals induced ND in mature oocytes and in the three subsets in which immature oocytes were fractionated. Though toxicity may play a significant unspecific role in the induction of chromosome malsegregation by DX and TU, the induction of ND at low doses, moderately toxic to the oocytes, suggests that the interaction with specific targets contributed to the results obtained.