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Open Access Highly Accessed Research article

Alterations in gene expression in Caenorhabditis elegans associated with organophosphate pesticide intoxication and recovery

John A Lewis1*, Elizabeth A Gehman2, Christine E Baer3 and David A Jackson1

Author Affiliations

1 US Army Center for Environmental Health Research, Fort Detrick, MD, USA

2 Current Address: The MITRE Corporation, McLean, VA, USA

3 Excet Inc., Fort Detrick, MD, USA

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BMC Genomics 2013, 14:291  doi:10.1186/1471-2164-14-291

Published: 30 April 2013

Abstract

Background

The principal toxicity of acute organophosphate (OP) pesticide poisoning is the disruption of neurotransmission through inhibition of acetylcholinesterase (AChE). However, other mechanisms leading to persistent effects and neurodegeneration remain controversial and difficult to detect. Because Caenorhabditis elegans is relatively resistant to OP lethality—particularly through the inhibition of AChE—studies in this nematode provide an opportunity to observe alterations in global gene expression following OP exposure that cannot be readily observed in less resistant organisms.

Results

We exposed cultures of worms in axenic, defined medium to dichlorvos under three exposure protocols. In the first, worms were exposed continuously throughout the experiment. In the second and third, the worms were exposed for either 2 or 8 h, the dichlorvos was washed out of the culture, and the worms were allowed to recover. We then analyzed gene expression using whole genome microarrays from RNA obtained from worms sampled at multiple time points throughout the exposure. The worms showed a time-dependent increase in the expression of genes involved in stress responses. Early in the exposure, the predominant effect was on metabolic processes, while at later times, an immune-like response and cellular repair mechanisms dominated the expression pattern. Following removal of dichlorvos, the gene expression in the worms appeared to relatively rapidly return to steady-state levels.

Conclusion

The changes in gene expression observed in the worms following exposure to dichlorvos point towards two potential mechanisms of toxicity: inhibition of AChE and mitochondrial disruption.

Keywords:
Caenorhabditis elegans; Organophosphate pesticide intoxication; Gene expression; Dichlorvos; Acetylcholinesterase inhibition; Mitochondrial disruption; Dichlorvos-induced developmental delay