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» Environmental Toxicology
Overview
Environmental toxicology refers to the scientific study of the potential effects upon organisms of anthropogenic compounds released into the natural environment. A large variety of chemicals, synthetic products and NCEs from unorganised sector are released in environment every year. To this rather exhaustive list have been added the novel materials like GMOs and Engineered Nano-Materials. The challenge is to create ways to efficiently and credibly predict toxic potency and exposure levels for chemicals that lack toxicological and exposure data in environmental settings. Both ethical and economic concerns over animal testing demand the principles of replacement, reduction and refinement be pursued for identification better tools to improve the efficiency of test design and field monitoring targets particularly ecotoxicity testing. Hence, alternate animal models as well as alternate to animal models are being explored more intensely today. Therefore, the development, validation and application of high throughput terrestrial and aquatic invertebrate test methods for ecotoxicity studies are high prioritity in ecotoxicology. The use, exposure and effects information obtained from quantitative structure-activity relationships, read-across methods, thresholds of toxicological concern and in vitro tests prior to in vivo testing are ideal route for more rapid, efficient, and cost effective risk assessment of chemicals. The application of "omics" approaches are expected to not only improve toxicity identification and evaluation procedures for investigating complex chemical mixtures but also identify when specific compounds are responsible for causing adverse effects. A major challenge is development of diagnostic capabilities to determine cause-effect relationships within impaired ecosystems. This will help in determining the extent to which existing remediation strategies/technologies are effective, and the refinements needed in risk management.
Mission and Goals:
To explore cellular, genetic and organismal approaches for detection and mitigation of environmental pollutants
Competencies:
Glimpses of Current Research
Hazardous effect of tannery solid waste leachates on development and reproduction in Drosophila melanogaster: 70 kDa heat shock protein as a marker of cellular damage Rapid industrialization has increased the burden of chemicals in the environment. These chemicals may be harmful to development and reproduction of any organism. We therefore analyzed the adverse effects of leachates from a tannery solid waste on development and reproduction using Drosophila. We show a significant delay in mean emergence of flies at the higher concentrations of the leachates, indicating their effect on the organism's development. Significant leachate-induction effect on reproduction of the organism was observed by leachate induction. Sub-organismal analyses revealed Hsp70 expression and tissue damage in a sex-specific manner. Refractoriness of Hsp70 expression in accessory glands of male flies and ovaries of females was concurrent with tissue damage. Genes encoding certain seminal proteins (Acp70A and Acp36DE) from accessory glands were significantly down-regulated at higher concentrations of the leachates. The study suggests that (i) sub-organismal adverse responses are reflected at organismal level, (ii) tannery waste leachates cause adverse effects on the expression of genes encoding seminal proteins that facilitate normal reproduction and (iii) Hsp70 may be used as a marker of cellular damage for reproductive organs. Siddique et.al. Ecotoxicology and Environmental Safety; 72: 1652-1662, 2009.
Effects of co-exposure of benzene, toluene and xylene to Drosophila melanogaster: alteration in hsp70, hsp60, hsp83, hsp26, ROS generation and oxidative stress markers Benzene, toluene and xylene are monocyclic aromatic hydrocarbon compounds, used both as individual compound and as mixtures, in industry as well as household. Earlier studies involving exposures to these compounds, individually, have shown that benzene was more toxic compared to toluene or xylene. Here, we tested a working hypothesis that toluene and/or xylene in a mixture containing benzene affect benzene induced toxicity in a nontarget organism, Drosophila melanogaster. We exposed D. melanogaster larvae transgenic for hsp70, hsp83 or hsp26 and wild type (Oregon R strain) larvae to 25.0-100.0mM benzene, 25.0-100.0mM toluene and 25.0-100mM xylene, individually or in mixtures. Subsequently, we examined the expression of stress genes (encoding heat shock proteins, hsps), generation of reactive oxygen species (ROS), induction of anti-oxidant stress markers and emergence of flies under treatment as well as control conditions. We observed that all these endpoints were significantly altered in all the treatment groups compared to their respective controls. However, the magnitude of toxicity of a benzene-toluene (BT) or benzene-xylene (BX) or benzene-toluene-xylene (BTX) mixture was significantly lower in the organism than that of individual chemical. Our results also show the modulation of toluene toxicity by xylene. Present study suggests antagonistic effect of xylene and toluene on benzene toxicity and additive/synergistic effect of xylene on toluene induced toxicity. Thus, expression of stress genes may be used as an assay for detection of early cellular toxicity. Further, our study supports the use of Drosophila as an alternative animal model for first tier screening of adverse effects of chemical mixtures. Singh et.al., Chemosphere; 79: 577-587,2010.
Environmental toxicology refers to the scientific study of the potential effects upon organisms of anthropogenic compounds released into the natural environment. A large variety of chemicals, synthetic products and NCEs from unorganised sector are released in environment every year. To this rather exhaustive list have been added the novel materials like GMOs and Engineered Nano-Materials. The challenge is to create ways to efficiently and credibly predict toxic potency and exposure levels for chemicals that lack toxicological and exposure data in environmental settings. Both ethical and economic concerns over animal testing demand the principles of replacement, reduction and refinement be pursued for identification better tools to improve the efficiency of test design and field monitoring targets particularly ecotoxicity testing. Hence, alternate animal models as well as alternate to animal models are being explored more intensely today. Therefore, the development, validation and application of high throughput terrestrial and aquatic invertebrate test methods for ecotoxicity studies are high prioritity in ecotoxicology. The use, exposure and effects information obtained from quantitative structure-activity relationships, read-across methods, thresholds of toxicological concern and in vitro tests prior to in vivo testing are ideal route for more rapid, efficient, and cost effective risk assessment of chemicals. The application of "omics" approaches are expected to not only improve toxicity identification and evaluation procedures for investigating complex chemical mixtures but also identify when specific compounds are responsible for causing adverse effects. A major challenge is development of diagnostic capabilities to determine cause-effect relationships within impaired ecosystems. This will help in determining the extent to which existing remediation strategies/technologies are effective, and the refinements needed in risk management.
Mission and Goals:
To explore cellular, genetic and organismal approaches for detection and mitigation of environmental pollutants
Competencies:
- Mechanism of toxicity of environmental pollutants
- Sensors and probes for detection of biological contaminants
- Remediation of soil, water and industrial wastes
- Ecotoxicity and environmental impact assessment
Glimpses of Current Research
Hazardous effect of tannery solid waste leachates on development and reproduction in Drosophila melanogaster: 70 kDa heat shock protein as a marker of cellular damage Rapid industrialization has increased the burden of chemicals in the environment. These chemicals may be harmful to development and reproduction of any organism. We therefore analyzed the adverse effects of leachates from a tannery solid waste on development and reproduction using Drosophila. We show a significant delay in mean emergence of flies at the higher concentrations of the leachates, indicating their effect on the organism's development. Significant leachate-induction effect on reproduction of the organism was observed by leachate induction. Sub-organismal analyses revealed Hsp70 expression and tissue damage in a sex-specific manner. Refractoriness of Hsp70 expression in accessory glands of male flies and ovaries of females was concurrent with tissue damage. Genes encoding certain seminal proteins (Acp70A and Acp36DE) from accessory glands were significantly down-regulated at higher concentrations of the leachates. The study suggests that (i) sub-organismal adverse responses are reflected at organismal level, (ii) tannery waste leachates cause adverse effects on the expression of genes encoding seminal proteins that facilitate normal reproduction and (iii) Hsp70 may be used as a marker of cellular damage for reproductive organs. Siddique et.al. Ecotoxicology and Environmental Safety; 72: 1652-1662, 2009.
Effects of co-exposure of benzene, toluene and xylene to Drosophila melanogaster: alteration in hsp70, hsp60, hsp83, hsp26, ROS generation and oxidative stress markers Benzene, toluene and xylene are monocyclic aromatic hydrocarbon compounds, used both as individual compound and as mixtures, in industry as well as household. Earlier studies involving exposures to these compounds, individually, have shown that benzene was more toxic compared to toluene or xylene. Here, we tested a working hypothesis that toluene and/or xylene in a mixture containing benzene affect benzene induced toxicity in a nontarget organism, Drosophila melanogaster. We exposed D. melanogaster larvae transgenic for hsp70, hsp83 or hsp26 and wild type (Oregon R strain) larvae to 25.0-100.0mM benzene, 25.0-100.0mM toluene and 25.0-100mM xylene, individually or in mixtures. Subsequently, we examined the expression of stress genes (encoding heat shock proteins, hsps), generation of reactive oxygen species (ROS), induction of anti-oxidant stress markers and emergence of flies under treatment as well as control conditions. We observed that all these endpoints were significantly altered in all the treatment groups compared to their respective controls. However, the magnitude of toxicity of a benzene-toluene (BT) or benzene-xylene (BX) or benzene-toluene-xylene (BTX) mixture was significantly lower in the organism than that of individual chemical. Our results also show the modulation of toluene toxicity by xylene. Present study suggests antagonistic effect of xylene and toluene on benzene toxicity and additive/synergistic effect of xylene on toluene induced toxicity. Thus, expression of stress genes may be used as an assay for detection of early cellular toxicity. Further, our study supports the use of Drosophila as an alternative animal model for first tier screening of adverse effects of chemical mixtures. Singh et.al., Chemosphere; 79: 577-587,2010.
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