Drosophila Melanogaster Somatic Mutation Research Articles

Surface Water Impacted by Rural Activities Induces Genetic Toxicity Related to Recombinagenic Events in Vivo.

This investigation assessed the interaction of surface water samples with DNA to quantitatively and qualitatively characterize their mutagenic and/or recombinagenic activity. Samples were obtained at three different sites along the Tocantins River (Tocantins State, Brazil). The area has withstood the impact mainly of rural activities, which release different chemical compounds in the environment. The Drosophila melanogaster Somatic Mutation and Recombination Test (SMART) was performed in standard (ST) and high bioactivation (HB) crosses. SMART is useful for the detection of mutational and recombinational events induced by genotoxins of direct and indirect action. Results demonstrated that samples collected in both seasons were able to induce increments on the mutant spot frequencies in the larvae of the HB cross. Genotoxicity was related to a massive recombinagenic activity. The positive responses ascribed to only the HB cross means that it is linked to pro-genotoxins requiring metabolic activation. The SMART wing test in Drosophila melanogaster was shown to be highly sensitive to detect genotoxic agents present in the aquatic environment impacted by agriculture.

Genotoxicity of Some Essential Oils Frequently Used in Aromatherapy

Genotoxic properties of the essential oils extracted from Artemisia dracunculus (tarragon), Ocimum basilicum (basil), Cinnamomum loureirii (cinnamon), Laurus nobilis (laurel), Satureja montana (savory) and Rosmarinus officinallis (rosemary) are studied by Drosophila melanogaster Somatic Mutation and Recombination Test (SMART). The high bioactivation crossed with a high cytochrome P450-dependent bioactivation capacity is used. This assay is principally based on the loss of heterozygosity of the suitable recessive markers’ multiple wing hairs (mwh) and flare-3 (flr3) which can lead to the formation of mutant clones of larval cells, and which are then going to be expressed as spots on the wings of adult flies. Third-instar larvae are treated for 48 hr with different concentrations of the essential oils dissolved in Tween-80 at 0.2% or 2%. The wings of the emerging adults are analyzed for the occurrence of different types of mutant spots. No statistically significant differences in spot frequencies between negative controls and treated series are observed. These results suggest that the six essential oils at concentrations tested are not genotoxic towards somatic cells of D. melanogaster.

Preliminary Results on Antigenotoxic Effects of Dried Mycelia of Two Medicinal Mushrooms in Drosophila melanogaster Somatic Mutation and Recombination Test

In this study, the antigenotoxic effects of dried mycelia from Trametes versicolor and Pleurotus ostreatus were investigated using a Drosophila melanogaster somatic mutation and recombination test (SMART), which is based on the principle that the loss of heterozygosity of suitable recessive marker hairs, such as multiple wing (mwh) and flare-3 (flr3), can lead to the formation of mutant clones of larval cells, which then are expressed as spots on the wings of the adult flies. In this study, dried mycelia from T. versicolor and P. ostreatus alone (7.5, 15, and 30 mg) were examined for genotoxicity and combined with mitomycin C (MMC; 0.05 mM) for antigenotoxicity. Commonly known mutagen which is mitomycin C (MMC) was used as positive control. The results showed that the dried mycelia of mushrooms were not genotoxic themselves. Nevertheless, the mushrooms have antigenotoxic activity by reducing the frequency of MMC-induced spots in varying proportions. Thus, powders of these 2 fungi were able to suppress somatic cell mutation induced by MMC. These results suggest that T. versicolor and P. ostreatus have antigenotoxic activity, including antirecombinogenic activity.

Recombinagenic and mutagenic activities of fluoroquinolones in Drosophila melanogaster

Fluoroquinolones are widely used in human and in veterinary medicine due to their broad-spectrum antibacterial activity. They act by inhibiting type II DNA topoisomerases (gyrase and topoisomerase IV). Because of the sequence homology between prokaryotic and eukaryotic topoisomerases II, fluoroquinolones can pose a hazard to eukaryotic cells. However, published information concerning the genotoxic profiles of these drugs in vivo is sparse and inconsistent. We have assessed the activities of three fluoroquinolones, ciprofloxacin, enrofloxacin and norfloxacin, in the Drosophila melanogaster Somatic Mutation and Recombination Test (SMART) and measured their mutagenic and recombinagenic potentials. Norfloxacin was non-genotoxic. Ciprofloxacin and enrofloxacin induced significant increases in spot frequencies in trans-heterozygous flies. To test the roles of somatic recombination and mutation in the observed genotoxicity, balancer-heterozygous flies were also analyzed. Ciprofloxacin and enrofloxacin were preferential inducers of homologous recombination in proliferative cells, an event linked to loss of heterozygosity.

Genotoxic evaluation of sodium fluoride in the Somatic Mutation and Recombination Test (SMART)

In this study, genotoxic effect of sodium fluoride (NaF) was investigated in Drosophila melanogaster Somatic Mutation and Recombination Test. Third-instar larvae trans-heterozygous for two genetic markers mwh and flr, were treated at different concentrations (2.5 μg/ml, 5 μg/ml and 10 μg/ml) of the test compounds. After the treatment the observed mutations were classified according to size and type of mutation per wing. For the evaluation of genotoxic effects, the frequencies of spots per wing in the treated series were compared to the control group, which is distilled water. NaF has genotoxic and toxic effects for concentrations of 5 and 10 μg/ml. The present study shows that NaF may have genotoxic and toxic effects.

Genotoxicity of water from the Paraguay River near Cáceres–MT, Brazil in the Drosophila wing‐spot test

The genotoxic activity of surface water samples from four sites along the Paraguay River, near Cáceres, Mato Grosso State, Brazil, was investigated using the Drosophila melanogaster Somatic Mutation and Recombination test (SMART). Effluents from sanitary sewers and agroindustrial effluents (residual effluents from slaughterhouses, leather tanneries, and dairies) flow into the Paraguay River, and directly or indirectly contaminate water from sampling sites 1-3. Site 4 was an upriver reference site that received no domestic or agroindustrial discharges. Water was collected at 4 time periods: September 2003 and August 2004 (periods of low water or drought); and April 2004 and March 2005 (periods of high water or flood). Chromium concentrations above statutory limits were detected at sites 1-3 (August 2004), and sites 1, 2 and 4 (March 2005). Sulfur compounds were also detected at sites 1-3. The SMART performed using standard (ST) cross flies detected genotoxic responses in only two samples, the August 2004 site 1 sample and the March 2005 site 2 sample. Many more samples were positive using high bioactivation (HB) cross flies: site 1 (all collection periods), site 2 (September 2003 and April 2004), and site 3 (September 2003 and August 2004). Mutant frequency comparisons between marker-heterozygous and balancer-heterozygous flies from the HB cross indicated that the positive genotoxic responses for the site 2 (April 2004) and site 3 (September 2003) samples were due mainly to mitotic recombination. Our findings indicate that the section of the Paraguay River within the urban perimeter of Cáceres is contaminated with genotoxic agents.

Antigenotoxic effects of Mandevilla velutina (Gentianales, Apocynaceae) crude extract on cyclophosphamide-induced micronuclei in Swiss mice and urethane-induced somatic mutation and recombination in Drosophila melanogaster

A Mandevilla velutina crude extract was investigated using the mouse micronucleus test (MNT) and the Drosophila melanogaster somatic mutation and recombination test (SMART) using standard (ST) and high bioactivation (HB) crosses. The MNT used 10 mg, 20 mg or 40 mg per 100 g of body weight (bw) of extract with and without 0.2 mg per 100 g bw peritoneal cyclophosphamide. There was no genotoxicity in the negative control or extract only groups and, compared to the cyclophosphamide control, there was a significant reduction in micronucleated polychromatic erythrocytes in all the groups given extract plus cyclophosphamide. For SMART larvae were fed 5 or 10 mg mL-1 of extract for seven days with and without 0.89 mg mL-1 of urethane given on day seven. The ST and HB flies showed no significant differences in spots between the negative control and the extract only groups. The number of urethane-induced spots was reduced by the highest concentration of extract for the ST flies and by both concentrations of extract for the HB flies. The results suggest that M. velutina extract is not genotoxic but is antigenotoxic.

Assessing the impact of pollution on the Japaratuba river in Brazil using the Drosophila wing spot test

The Drosophila melanogaster somatic mutation and recombination test (SMART) was used to assess the genotoxicity of surface (S) and bottom (B) water and sediment samples collected from Sites 1 and 2 on the Japaratuba River (Sergipe, Brazil), an area impacted by a petrochemical industrial complex that indirectly discharges treated effluent (produced water) into the river. The genotoxicity tests were performed in standard (ST) cross and high bioactivation (HB) cross flies and were conducted on samples taken in March (dry season) and in July (rainy season) of 2003. Mutant spot frequencies found in treatments with unprocessed water and sediment samples from the test sites were compared with the frequencies observed for similar samples taken from a clean reference site (the Jacarecica River in Sergipe, Brazil) and those of negative (ultrapure water) controls. While samples from the Japaratuba River generally produced greater responses than those from the Jacarecica River, positive responses were detected for both the test and reference site samples. All the water samples collected in March 2003 were genotoxic. In July 2003, the positive responses were restricted to water samples collected from Sites 1 B and 2 S in the ST cross. The genotoxicity of the water samples was due to mitotic recombination, and the samples produced similar genotoxic responses in ST and HB flies. The spot frequencies found in the July water samples were considerably lower than those for the March water samples, suggesting a seasonal effect. The only sediment samples that were genotoxic were from Site 1 (March and July) and from the Jacarecica River (March). The genotoxins in these samples produced both somatic mutation (limited to the Site 1 sample in HB flies) and recombination. The results of this study indicate that samples from both the Japaratuba and Jacarecica Rivers were genotoxic, with the most consistently positive responses detected with Site 1 samples, the site closest to the putative pollution source.

Genotoxicity of dill ( Anethum graveolens L.), peppermint ( Mentha×piperita L.) and pine ( Pinus sylvestris L.) essential oils in human lymphocytes and Drosophila melanogaster

Genotoxic properties of the essential oils extracted from dill ( Anethum graveolens L.) herb and seeds, peppermint ( Mentha×piperita L.) herb and pine ( Pinus sylvestris L.) needles were studied using chromosome aberration (CA) and sister chromatid exchange (SCE) tests in human lymphocytes in vitro, and Drosophila melanogaster somatic mutation and recombination test (SMART) in vivo. In the CA test, the most active essential oil was from dill seeds, then followed essential oils from dill herb, peppermint herb and pine needles, respectively. In the SCE test, the most active essential oils were from dill herb and seeds followed by essential oils from pine needles and peppermint herb. Essential oils from dill herb and seeds and pine needles induced CA and SCE in a clear dose-dependent manner, while peppermint essential oil induced SCE in a dose-independent manner. All essential oils were cytotoxic for human lymphocytes. In the SMART test, a dose-dependent increase in mutation frequency was observed for essential oils from pine and dill herb. Peppermint essential oil induced mutations in a dose-independent manner. Essential oil from dill seeds was almost inactive in the SMART test.