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Modified comet assay to determine oxidative damage to DNA in aquatic organisms: role of confounding factors influencing the results

Awadhesh N. Jha1*
  • 1 Plymouth University, Biological Sciences, United Kingdom

In common with human health arena, oxidative damage to DNA could play an important role in the development of pathophysiological conditions and ultimately Darwinian fitness of the wild species. Despite the importance, not enough information is available in the literature pertaining to the determination of oxidative damage to DNA in wild species. Among the aquatic organisms, bivalve molluscs and fish species have been widely used for ecotoxicological studies and for the determination of DNA strand breaks using the standard comet assay. For these organisms, the widely used cell types are haemocytes for molluscs and erythrocytes for fish, although other cell types (e.g. gill cells) are also used. Whilst a large number of studies have been carried out using standard comet assay, applications of modified comet assay using bacterial enzymes to determine oxidative damage to DNA has been very limited. We have used these cell types from fish and bivalve species and have determined the oxidative damage to DNA following exposure to a range of environmental stressors (e.g. metals, nanoparticles and hypoxia). Overall these studies suggest that while in vitro optimisation studies using hydrogen peroxide provide a concentration-dependent response, the results do not always mirror the in vitro response in in vivo situations. This disparity could be attributed to different study designs, stressors used in addition to different confounding factors which influence the determination of different biological parameters. More research is therefore required to optimise the application of modified comet assay in different cell types of aquatic organisms before it is widely used for ecotoxicological studies.

References

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Mustafa, S.A., Davies, S.J., Jha A.N. (2012) Determination of hypoxia and dietary copper mediated sub-lethal toxicity in carp, Cyprinus carpio, at different levels of biological organisation. Chemosphere 87, 413-422.

Mustafa, S.A., Al-Subiai, S.N., Davies, S.J., Jha, A.N. (2011) Hypoxia-induced oxidative DNA damage links with higher level biological effects including specific growth rate in common carp, Cyprinus carpio L. Ecotoxicology 20, 1455-1466.

Jha, A.N. (2008) Ecotoxicological applications and significance of the comet assay. Mutagenesis 23, 207-221.

Jha, A.N. (2004) Genotoxicological studies in aquatic organisms: an overview. (invited review article). Mutation Research (Fundamental and Molecular Mechanisms of Mutagenesis): 552, 1-17.

Dixon, D.R., Pruski, A.M., Dixon, L.R.J., Jha, A.N. (2002) Marine invertebrate eco-genotoxicology: a methodological overview. Mutagenesis 17, 495-507.

Keywords: Modified comet assay, Aquatic Organisms, Oxidative damage, fish, mussels

Conference: ICAW 2015 - 11th International Comet Assay Workshop, Antwerpen, Belgium, 1 Sep - 4 Sep, 2015.

Presentation Type: Oral Presentation

Topic: Statistical issues within comet assay studies

Citation: Jha AN (2015). Modified comet assay to determine oxidative damage to DNA in aquatic organisms: role of confounding factors influencing the results. Front. Genet. Conference Abstract: ICAW 2015 - 11th International Comet Assay Workshop. doi: 10.3389/conf.fgene.2015.01.00022

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Received: 02 Jun 2015; Published Online: 23 Jun 2015.

* Correspondence: Prof. Awadhesh N Jha, Plymouth University, Biological Sciences, Plymouth, Devon, PL4 8AA, United Kingdom, a.jha@plymouth.ac.uk