Characterization of the effects of methylmercury on Caenorhabditis elegans

• Published in: Toxicology and applied pharmacology 2009-10, Vol.240 (2), p.265-272
• Main Authors: Helmcke, Kirsten J., Syversen, Tore, Miller, David M., Aschner, Michael
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; Animals; Caenorhabditis elegans; Caenorhabditis elegans - drug effects; Caenorhabditis elegans - embryology; Caenorhabditis elegans - growth & development; Caenorhabditis elegans - metabolism; Dose-Response Relationship, Drug; Drug Resistance; Environmental Pollutants - metabolism; Environmental Pollutants - toxicity; HUMAN POPULATIONS; Larva - drug effects; Larva - metabolism; Longevity - drug effects; MAMMALS; MERCURY; METHYLMERCURY; Methylmercury Compounds - metabolism; Methylmercury Compounds - toxicity; Nematoda; NEMATODES; NERVE CELLS; NERVOUS SYSTEM; Nervous System - drug effects; Nervous System - embryology; Nervous System - growth & development; Nervous System - metabolism; Neurogenesis - drug effects; Neurons - drug effects; Neurons - metabolism; Pharyngeal Muscles - drug effects; Pharyngeal Muscles - growth & development; Reproduction - drug effects; Time Factors; TOXICITY
• ISSN: 0041-008X; 1096-0333
• DOI: 10.1016/j.taap.2009.03.013

The rising prevalence of methylmercury (MeHg) in seafood and in the global environment provides an impetus for delineating the mechanism of the toxicity of MeHg. Deleterious effects of MeHg have been widely observed in humans and in other mammals, the most striking of which occur in the nervous system. Here we test the model organism, Caenorhabditis elegans (C. elegans), for MeHg toxicity. The simple, well-defined anatomy of the C. elegans nervous system and its ready visualization with green fluorescent protein (GFP) markers facilitated our study of the effects of methylmercuric chloride (MeHgCl) on neural development. Although MeHgCl was lethal to C. elegans, induced a developmental delay, and decreased pharyngeal pumping, other traits including lifespan, brood size, swimming rate, and nervous system morphology were not obviously perturbed in animals that survived MeHgCl exposure. Despite the limited effects of MeHgCl on C. elegans development and behavior, intracellular mercury (Hg) concentrations (≤ 3 ng Hg/mg protein) in MeHgCl-treated nematodes approached levels that are highly toxic to mammals. If MeHgCl reaches these concentrations throughout the animal, this finding indicates that C. elegans cells, particularly neurons, may be less sensitive to MeHgCl toxicity than mammalian cells. We propose, therefore, that C. elegans should be a useful model for discovering intrinsic mechanisms that confer resistance to MeHgCl exposure.