Article

DNA damage induced by industrial solid waste leachates in Drosophila melanogaster: a mechanistic approach.

Embryotoxicology Section, Industrial Toxicology Research Centre, Lucknow, Uttar Pradesh, India.
Environmental and Molecular Mutagenesis (Impact Factor: 3.71). 05/2008; 49(3):206-16. DOI: 10.1002/em.20373
Source: PubMed

ABSTRACT Genomic stability requires that error-free genetic information be transmitted from generation to generation, a process that is dependent upon efficient DNA repair. Industrial leachates which contain mixtures of diverse chemicals are a major environmental concern. The interaction between these chemicals may have synergistic, antagonistic, or simply additive effects on biological systems. In the present study, the Comet assay was used to measure the DNA damage produced by leachates of solid wastes from flashlight battery, pigment, and tanning factories in the midgut cells and brain ganglia of Drosophila melanogaster mutants deficient in DNA repair proteins. Larvae were allowed to feed for 48 or 72 hr on diets containing 0.1, 0.5, and 2.0% (v/v) of the leachates. Physicochemical analysis run on the solid wastes, leachates, and treated larvae detected elevated levels of heavy metals. Leachates produced significantly greater levels of DNA damage in mutant strains mei41 (deficient in cell cycle check point protein), mus201 (deficient in excision repair protein), mus308 (deficient in postreplication repair protein), and rad54 (deficient in double strand break repair protein) than in the OregonR(+) wild-type strain. Larvae of the ligaseIV mutant (deficient in double strand break repair protein) were hypersensitive only to the pigment plant waste leachate. Conversely, the dnase2 mutant (deficient in protein responsible for degrading fragmented DNA) was more sensitive to DNA damage induction from the flashlight battery and tannery waste leachates. Our data demonstrate that repair of DNA damage in organisms exposed to leachates is dependent upon several DNA repair proteins, indicative of the involvement of multiple overlapping repair pathways. The study further suggests the usefulness of the Comet assay for studying the mechanisms of DNA repair in Drosophila.

0 Bookmarks
 · 
145 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Solid waste production is inevitable and its unsanitary disposal in the environment is of public and environmental health concern. Leachate, generated due to the infiltration of water/precipitation through the waste mass and the wastes biodegradation, is a mixture of dissolved organic matter, inorganic macro-components, heavy metals, xenobiotic organic compounds and microorganisms. Several studies have reported the acute toxicity of leachate using different end points, while evidences are accumulating on their potentials to induce genetic damage. In this wise, different short-term in vivo and in vitro bioassays are being utilized in the evaluations of genotoxicity and mutagenicity of leachates; and the possible mechanisms of genetic damage. This paper reviews reports on leachate-induced genetic damage. There is need for a shift from waste disposal to sustainable waste management. Awareness on possible health impacts or consequences of exposure to solid waste should also be created through health education.
    AFRICAN JOURNAL OF BIOTECHNOLOGY 07/2013; 12(27):4206 - 4220. · 0.57 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Hexavalent chromium [Cr(VI)] is a well known mutagen and carcinogen. Since genomic instability due to generation of double strand breaks (DSBs) is causally linked to carcinogenesis, we tested a hypothesis that Cr(VI) causes in vivo generation of DSBs and elicits DNA damage response. We fed repair proficient Drosophila melanogaster (Oregon R(+)) larvae Cr(VI) (20.0μg/ml) mixed food for 24 and 48h and observed a significant (p<0.05) induction of DSBs in their midgut cells after 48h using neutral Comet assay. Global gene expression profiling in Cr(VI)-exposed Oregon R(+) larvae unveiled mis-regulation of DSBs responsive repair genes both after 24 and 48h. In vivo generation of DSBs in exposed Drosophila was confirmed by an increased pH2Av immunostaining along with the activation of cell cycle regulation genes. Analysis of mis-regulated genes grouped under DSB response by GOEAST indicated the participation of non-homologous end joining (NHEJ) DSB repair pathway. We selected two strains, one mutant (ligIV) and another ku80-RNAi (knock down of ku80), whose functions are essentially linked to NHEJ-DSB repair pathway. As a proof of principle, we compared the DSBs generation in larvae of these two strains with that of repair proficient Oregon R(+). Along with this, DSBs generation in spn-A and okr [essential genes in homologous recombination repair (HR) pathway] mutants was also tested for the possible involvement of HR-DSB repair. A significantly increased DSBs generation in the exposed ku80-RNAi and ligIV (mutant) larvae because of impaired repair, concomitant with an insignificant DSBs generation in okr and spn-A mutant larvae indicates an active participation of NHEJ repair pathway. The study, first of its kind to our knowledge, while providing evidences for in vivo generation of DSBs in Cr(VI) exposed Drosophila larvae, assumes significance for its relevance to higher organisms due to causal link between DSB generation and Cr(VI)-induced carcinogenesis.
    Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 04/2013; · 3.90 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Dichlorvos (DDVP), an organophosphate pesticide, is reported to induce genotoxicity in in vitro and in certain in vivo models at its higher concentrations. However, studies on the affected DNA damage repair pathways are elusive. Hypersensitivity of mutagen sensitive strains (mus) in Drosophila to mutagens and chemicals are known and accordingly, these mutants were grouped in pre- and post-replication repair pathways. For examining chemical-induced genotoxicity, mutants belonging to one particular repair pathway may not be adequate when other repair pathways may neutralize its effect. To test whether both pre- and post-replication pathways are affected by DDVP-induced genotoxicity in exposed Drosophila, we examined changes in DNA migration of Comet assay in the midgut cells of Oregon R+ larvae and selected mutants of pre- (mei-9, mus201 and mus207) and post-replication (mei-41 and mus209) repair pathways exposed to increasing yet environmentally relevant concentrations of DDVP (0.0, 0.15, 1.5 and 15.0 ng/ml) for 48 h. We observed greater DNA damage in pre-replication repair mutants after exposure to 0.15 ng/ml DDVP, while effects on Oregon R+ and post-replication repair mutants were insignificant. On the other, significant DNA damage was observed in the post-replication repair mutants after their exposure to 1.5 and 15.0 ng/ml DDVP. Among the mutants, pre-replication repair mutant, mus207, exhibited maximum sensitivity to DDVP which is suggestive of alkylation damage to DNA apart from its role in DSB repair. We also examined mutants (SOD- and urate-null) that are sensitive to oxidative stress and observed significant oxidative DNA damage in DDVP exposed mutants as compared to Oregon R+. The present study suggests requirement of both pre- and post-replication repair pathways against DDVP induced DNA damage in Drosophila with increased oxidative DNA damage leading to increased genotoxicity.
    Mutation Research/Genetic Toxicology and Environmental Mutagenesis 01/2014; · 2.22 Impact Factor

Full-text

View
99 Downloads
Available from
Jun 4, 2014