Demethylation and placental transfer of methyl mercury in the pregnant hamster

Dock, Lennart; Rissanen, Riitta‐Liisa; Vahter, Marie

doi:10.1016/0300-483x(94)90033-7

Cited by 41 publications

(17 citation statements)

References 28 publications

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“…Instead, the enhanced sensitivity of L1 stage larvae may be due to inhibition of essential developmental pathways including, for example, mechanisms for detoxifying MeHgCl that could be in place in the more mature L4 larvae. Mammalian systems have displayed an inability to demethylate MeHg until after birth, indicating that in mammals, the processes involved in demethylation as a form of detoxification do not develop until later in life (Dock et al , 1994). Furthermore, MeHgCl displayed increased toxicity as duration of exposure increased (Figure 1), indicating that increased accumulation of Hg within C. elegans (Figure 2) may be responsible for this increased toxicity instead of an increased duration of exposure to the toxicant.…”

Section: Discussionmentioning

confidence: 99%

Characterization of the effects of methylmercury on Caenorhabditis elegans

Helmcke

Syversen

Miller

et al. 2009

Toxicology and Applied Pharmacology

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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.

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Section: Discussionmentioning

confidence: 99%

Characterization of the effects of methylmercury on Caenorhabditis elegans

Helmcke

Syversen

Miller

et al. 2009

Toxicology and Applied Pharmacology

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“…Considerable transfer of MeHg across the placenta and during lactation is evident for mammals, including mink, exposed to dietary MeHg under laboratory conditions (e.g., Wren et al 1987;Dock et al 1994;Wolfe et al 1998;Dansereau et al 1999). Concentrations of Hg in fetal tissues are correlated with maternal concentrations suggesting placental transfer of MeHg in field-caught otter (Beck 1977cited in Wren 1986aHalbrook et al 1994).…”

Section: Age-related Effectsmentioning

confidence: 95%

Hepatic mercury, cadmium, and lead in mink and otter from New York State: monitoring environmental contamination

Mayack

2011

Environ Monit Assess

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Many non-linear processes link atmospheric emissions to the bioavailability of metals; consequently, the monitoring of metals in ecosystem components is required to model their ecodynamics. American mink (Neovison vison) and river otter (Lontra canadensis) have the potential to serve as an upper-level-consumer component in monitoring metals bioavailability. However, the relationship of bioaccumulated metals to various environmental factors has not been explored nor have the effects of demographic factors been resolved. To address these limitations, mink and otter, collected throughout New York State during 1998-2002, were analyzed for hepatic concentrations of total mercury (Hg), cadmium (Cd), and lead (Pb). Relationships were investigated between metals concentrations and landscape-level factors (physiographic zone, hydrologic unit, and elevation) and demographic factors (gender and age). Considerable variation in Hg and Cd concentrations was observed relative to both physiographic zone and hydrologic unit for both species. In contrast with Hg, Cd concentration increased predictably with increasing elevation. Mercury concentrations were greater, but for Cd less, in otter than mink. Lead concentrations showed little landscape heterogeneity and were independent of elevation. Age-related bioaccumulation was evident for Hg and Cd, but not for Pb, in both species. Mercury and Cd concentrations were greater in female than male mink; however, Pb concentrations were greater in males than females. Inverse relationships of relative growth (weight/length) to metals concentrations explained gender differences in Hg and Cd in mink. For otter, no gender-related differences in metals concentrations were apparent. The suitability of mink and otter for monitoring programs is discussed.

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“…The absorption of Hg 0 in the lung is about 80% [11]. Within tissues, MeHg is slowly demethylated to Hg 2+ [12,13]. In the blood, Hg 0 is readily oxidized to Hg 2+ by catalase [14].…”

Section: Introductionmentioning

confidence: 99%