Aneugenic, clastogenic, and multi-toxic effects of diethyl phthalate exposure.

Diethyl phthalate (DEP) is a compound which is used in many industrial fields, especially in cosmetic sector and causes contamination in air, water, and soil due to its widespread usage. In this study, the potential toxic effects of DEP were investigated by using physiological, anatomical, biochemical, and cytogenetic parameters in Allium cepa. The micronucleus (MN) test specifically aimed to elucidate the aneugenic and clastogenic effects of DEP. Physiological effects were determined by germination percentage, root length, weight gain parameters, and cytogenetic effects were investigated by mitotic index (MI) and chromosomal abnormality (CA) test. Malondialdehyde (MDA) level, catalase (CAT), and superoxide dismutase (SOD) activities were investigated as oxidative damage indicators and structural changes were investigated with anatomical cross sections. For this purpose, Allium cepa bulbs were divided into four groups as control and application groups and the application groups were germinated with 1.0, 2.2, and 4.4 µM DEP for 72 h. As a result, it was determined that germination percentage, weight gain and root length decreased, CA frequency, MDA level, SOD, and CAT activities were increased in DEP-treated groups when compared with the control group. DEP has been found to induce CA in root tip cells such as fragment, chromosome bridge, c-mitosis, sticky chromosome, and unequal chromatin distribution. When MN formations induced by DEP application were examined, both large-scale and small-scale MNs were determined. MN formation in both sizes indicates that DEP has both clastogenic and aneugenic effects. And also, it was found that DEP application caused structural changes and especially anatomic damages such as necrosis in 4.4 µM DEP application. As a result, it was found that DEP caused various toxic effects depending on the dose and that A. cepa test material was a useful indicator in determining these effects.

Assessing effects of germline exposure to environmental toxicants by high-throughput screening in C. elegans.

Chemicals that are highly prevalent in our environment, such as phthalates and pesticides, have been linked to problems associated with reproductive health. However, rapid assessment of their impact on reproductive health and understanding how they cause such deleterious effects, remain challenging due to their fast-growing numbers and the limitations of various current toxicity assessment model systems. Here, we performed a high-throughput screen in C. elegans to identify chemicals inducing aneuploidy as a result of impaired germline function. We screened 46 chemicals that are widely present in our environment, but for which effects in the germline remain poorly understood. These included pesticides, phthalates, and chemicals used in hydraulic fracturing and crude oil processing. Of the 46 chemicals tested, 41% exhibited levels of aneuploidy higher than those detected for bisphenol A (BPA), an endocrine disruptor shown to affect meiosis, at concentrations correlating well with mammalian reproductive endpoints. We further examined three candidates eliciting aneuploidy: dibutyl phthalate (DBP), a likely endocrine disruptor and frequently used plasticizer, and the pesticides 2-(thiocyanomethylthio) benzothiazole (TCMTB) and permethrin. Exposure to these chemicals resulted in increased embryonic lethality, elevated DNA double-strand break (DSB) formation, activation of p53/CEP-1-dependent germ cell apoptosis, chromosomal abnormalities in oocytes at diakinesis, impaired chromosome segregation during early embryogenesis, and germline-specific alterations in gene expression. This study indicates that this high-throughput screening system is highly reliable for the identification of environmental chemicals inducing aneuploidy, and provides new insights into the impact of exposure to three widely used chemicals on meiosis and germline function.

Detection of aneugenicity and clastogenicity in buccal epithelial cells of pan masala and gutkha users by pan-centromeric FISH analysis.

Chewing of betel quid, smoking and alcohol consumption are all associated with higher incidences of oral cancer. Genetic damage can be detected by fluorescent in situ hybridization (FISH) using human centromeric probes. In the present study FISH was performed on buccal epithelial cells of pan masala and gutkha chewers alone with and without additional tobacco smoking and/or alcohol consumption. The study comprised of 1500 male individuals. The present study found the highest frequency of micronuclei without a centromeric region (MN(-)) among gutkha users who also smoked and drank (P < 0.05). A significant increase in cells having micronuclei with a centromeric region (MN(+)) was observed among pan masala users who also smoked (P < 0.05). The study reveals that the clastogenic effects of pan masala/gutkha increase with smoking and alcohol consumption, but aneugenic effects were also observed among the pan masala chewers who smoked.

Comparative aneugenicity of doxorubicin and its derivative idarubicin using fluorescence in situ hybridization techniques.

The present study was designed to evaluate and compare the aneugenicity of idarubicin and doxorubicin, topoisomerase-targeting anticancer anthracyclines, using fluorescence in situ hybridization techniques. It was found that idarubicin and doxorubicin treatment (12 mg/kg) induced sperm meiotic delay of 24h. To determine the frequencies of disomic and diploid sperm, groups of 5 male Swiss albino mice were treated with 3, 6 and 12 mg/kg idarubicin or doxorubicin. Significant increases in the frequencies of disomic and diploid sperm were caused by treatment with all doses of idarubicin and the two highest doses of doxorubicin compared with the controls. Moreover, both compounds significantly increased the frequency of diploid sperm, indicating that complete meiotic arrest occurred. The observation that XX- and YY-sperm significantly prevailed XY-sperm indicates missegregation during the second meiotic division. The results suggest also that earlier prophase stages contribute relatively less to idarubicin and doxorubicin-induced aneuploidy. Effects of the same doses were investigated by the bone-marrow micronucleus test. Significant increases in the frequencies of micronuclei were found after treatment with all doses of both compounds. The responses were also directly correlated with bone marrow suppression. Idarubicin was more toxic than doxorubicin. Exposure to 12 mg/kg of idarubicin and doxorubicin yielded 3.82 and 2.64% micronuclei, respectively, and of these an average of 58.3 and 62.8%, respectively, showed centromeric signals, indicating their formation by whole chromosomes and reflecting the aneugenic activity of both compounds. Correspondingly, about 41.7 and 37.2% of the induced micronuclei, respectively, were centromere-negative, demonstrating that both compounds not only induce chromosome loss but also DNA strand breaks. Based on our data, aneuploidy assays such as sperm-fluorescence in situ hybridization assay and micronucleus test complemented by fluorescence in situ hybridization with centromeric DNA probes have been to some extent validated to be recommended for the assessment of aneuploidogenic effects of chemicals.

Genotoxicity of lavender oil, linalyl acetate, and linalool on human lymphocytes in vitro.

The potential genotoxicity of lavender essential oil and its major components, linalool, and linalyl acetate, was evaluated in vitro by the micronucleus test on peripheral human lymphocytes. In the range of non-toxic concentrations (0.5-100 µg/ml), linalyl acetate increased the frequency of micronuclei significantly and in concentration-dependent manner; lavender oil did so only at the highest concentration tested, whereas linalool was devoid of genotoxicity. None of the tested substances led to an increase in nucleoplasmic bridges or nuclear buds frequency. These findings suggest that the mutagenic activity of lavender oil can be related to the presence of linalyl acetate, which seems to have a profile of an aneugenic agent.

Aneugenic effects of benzoxazinones in cultured human cells.

Benzoxazinones (BAs) are natural products that are present in Gramineae and represent part of the plant defence system against pests. In recent years, sprouts of maize, wheat and rye have been used for the production of dietary supplements. We have investigated the potential genotoxic activities of a diverse range of synthetic derivatives of the most abundant natural BA, namely DIBOA (2,4-dihydroxy-1,4-benzoxazin-3-one), proposed for use as a potential herbicide. We have tested 18 synthetic BAs for potential effects in cultured HeLa cells. We found significantly higher micronucleus (MN) induction over the background level, with the solvent DMSO used as an internal control. Concentration-dependent effects were found between 1nM and 20nM for all the synthetic compounds studied. Immunostaining with an anticentromere antibody showed that >80% of MN induced gave a centromere-positive signal. Similarly, fluorescence in situ hybridization (FISH) analysis with alphoid centromere probes showed a positive hybridization signal, indicating that all compounds analyzed are aneugenic. Chemical modification of the N in the heterocyclic aromatic amine served us to suggest a relationship between the structure and the aneugenic effects of the compounds analyzed. Our findings indicate that benzoxazinoids could be potential genotoxins for human cells.

Origin of nuclear and chromosomal alterations derived from the action of an aneugenic agent--Trifluralin herbicide.

Trifluralin is a herbicide capable of interfering in mitotic cell division due to either microtubule depolymerization or alteration in the concentration of calcium ions within the cell. The aim of this study was to investigate the effects of trifluralin in Allium cepa meristematic cells, evaluating the induction mechanisms of the chromosomal and nuclear aberrations. In this study, A. cepa root tips were submitted for 24h treatment to several concentrations of this herbicide and 48 h recovery post-treatment. The results showed that some concentrations of trifluralin can lead to a mitotic index inhibition, besides inducing chromosomal and nuclear alterations throughout the mitotic cycle. Some of the alterations found seem to be resulting from the herbicide action in different phases and in more than one consecutive cell cycle.