Inability of Fish to Methylate Mercuric Chloride In Vivo

Pennacchioni, A.; Marchetti, Rosa; Gaggino, G.F.

doi:10.2134/jeq1976.00472425000500040027x

Cited by 31 publications

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“…Whether there was any biotransformation (methylation and demethylation) within the fish body was not revealed by our study. Pennacchioni et al (1976) suggested that fishes are unable to methylate Hg in vivo, whereas other studies indicated that methylation and demethylation are possible (Burrows & Krenkel 1973, Simon & Boudou 2001). We found a significant difference in the AE, the uptake rate constant, and the elimination rate constant between Hg(II) and MeHg.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…gills, brains, viscera) has not been extensively quantified. There is some evidence of considerable methylation and demethylation in fish muscle (Burrows & Krenkel 1973, Simon & Boudou 2001, although some studies have also indicated that fishes are unlikely to methylate the inorganic Hg to MeHg within their tissues in vivo (Pennacchioni et al 1976).In this study, we examined the biokinetics of both Hg(II) and MeHg in a marine predatory fish (the sweetlips Plectorhinchus gibbosus) during both the aqueous and dietary phases. Sweetlips is important fish species widely cultured in China, and is used either as fish food or for direct human consumption.…”

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Bioaccumulation kinetics and exposure pathways of inorganic mercury and methylmercury in a marine fish, the sweetlips Plectorhinchus gibbosus

Wang¹,

Wong²

2003

Mar. Ecol. Prog. Ser.

142

111

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We experimentally determined the assimilation efficiency (AE) of ingested prey, the uptake-rate constant from the aqueous phase, and elimination-rate constant of both inorganic Hg (Hg [II]) and methylmercury (MeHg) in a marine predatory fish, the sweetlips Plectorhinchus gibbosus, using radiotracer techniques. The AE of Hg(II) and MeHg ranged between 10 and 27% and between 56 and 95%, respectively, for 3 different prey (copepods, silverside, and brine shrimp). The ingestion rate of the fish did not significantly affect the AE of Hg(II). Uptake of both species of Hg proceeded in a linear pattern, and the calculated uptake-rate constant was 0.195 and 4.515 l g -1 d -1 for Hg(II) and MeHg, respectively. Most of the accumulated Hg(II) was distributed in muscle tissues, whereas the accumulated MeHg was distributed evenly between gills and muscle tissues. The calculated elimination-rate constants for MeHg were 0.0103 and 0.0129 d -1 following dietary and aqueous uptake, respectively, whereas the elimination-rate constant of Hg(II) following dietary uptake (0.0547 d -1 ) was 1.9 times higher than the elimination following aqueous uptake (0.0287 d -1 ). These experimentally determined values were incorporated into a kinetic model to predict the exposure pathways and the relative contribution of Hg(II) and MeHg to the sweetlips. At the high end of the bioconcentration factor for both species of Hg in the prey, dietary ingestion is likely to be the main channel for their accumulation in the fish. The relative contribution of Hg(II) vs MeHg to the overall Hg bioaccumulation is largely controlled by the relative concentration of MeHg dissolved in seawater. Similar to the results of numerous field studies, the kinetic model predicted a potential trophic transfer factor of < 0.6 for Hg(II) and >1 for MeHg under conditions likely to be experienced by the fish in its natural environment. KEY WORDS: Mercury · Methylmercury · Exposure · Fish · Kinetic modeling Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 261: [257][258][259][260][261][262][263][264][265][266][267][268] 2003 bioavailability of these Hg species in marine fishes are less well studied (Pentreath 1976a,b, Honda et al. 1978, Barkay et al. 1997, Rouleau et al. 1998.Most previous studies measured the concentration of different Hg species in different tissues of fishes (Leah et al. 1991, Monteiro et al. 1996, Joiris et al. 2000. The routes of Hg accumulation, including the relative importance of different Hg species (inorganic and organic) and exposure pathways (aqueous vs dietary),are not yet well understood. Whereas it has generally been assumed that fishes accumulate MeHg mainly from dietary sources through very efficient assimilation of this compound (Mason 2002), it is quite possible that, because of its highly efficient absorption properties, they accumulate it from the aqueous phase also. Experimental studies on the routes of methylmercury exposure in fishes are indeed rather controversial (Honda et...

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Bioaccumulation kinetics and exposure pathways of inorganic mercury and methylmercury in a marine fish, the sweetlips Plectorhinchus gibbosus

Wang¹,

Wong²

2003

Mar. Ecol. Prog. Ser.

142

111

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“…Because most of the Hg (Ͼ95%) in fish is methylmercury (Bloom 1989(Bloom , 1992, this MMBM assumes that there is no conversion of inorganic Hg potentially contained in the ingested prey to methylmercury in the intestine of fish (Pennacchioni et al 1976, Pentreath 1976, Huckabee et al 1978. Rudd et al (1980) reported that fish intestinal contents could methylate inorganic Hg in vitro, though the fraction of inorganic Hg that was methylated was fairly small (0.005-0.4%/ d) and can assumed negligible in fish.…”

Section: Mercury Mass Balance Modelmentioning

confidence: 99%

Predicting Mercury Concentration in Fish Using Mass Balance Models

Trudel

Rasmussen

2001

Ecological Applications

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Mass balance models have frequently been used with laboratory-derived bioenergetic models to examine the accumulation of mercury (Hg) in fish. The accumulation of Hg in fish has usually been successfully described by these models. However, this has generally been achieved by adjusting the parameters of these models until there was a close fit between observed and predicted values. In this study, we present a simple Hg mass balance model (MMBM) to predict Hg concentration in fish. This MMBM was applied with three methods of estimating food consumption rates to predict Hg concentration in three freshwater fish species. The MMBM accurately predicted the accumulation of Hg in the three fish species examined in this study when it was combined with food consumption rates that were determined with a radioisotopic method. The MMBM tended to underestimate Hg concentration in fish when it was combined with food consumption rates determined using laboratory-derived bioenergetic models, possibly because activity costs derived under laboratory conditions do not adequately represent activity costs of fish in the field. When feeding rates were estimated with a bioenergetic model implemented with site-specific estimates of activity costs, the MMBM accurately predicted the concentration of Hg in fish. Therefore, until activity costs can be accurately estimated in situ, predictions obtained with the MMBM implemented with a laboratory-derived bioenergetic model should be interpreted cautiously.

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“…Methylmercury (CH,Hg+) is the major form of mercury in fish [10,11]. Because fish tissues and organs do not methylate mercury [ 12,131, the elevated mercury levels of fish in acidic lakes must be a result of increased bioaccumulation of methylmercury. Methylmercury is produced by the methylation of inorganic mercury (Hg[II]) [14] in the terrestrial environment [15], in the water column [16] and sediment of lakes [17], and in the intestines [18] and external slime layer of fish 1191.…”

Section: The Relationship Between Mercury In Fish and Lake P Hmentioning

confidence: 99%

Environmental factors affecting the formation of methylmercury in low pH lakes

Winfrey

Rudd

1990

Enviro Toxic and Chemistry

334

150

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Recent studies have demonstrated elevated levels of mercury in fish from remote, low alkalinity and low pH lakes. The mechanisms of this enhanced bioaccumulation are poorly understood, but the amount of methylmercury produced in a lake can play a major role. Decreased pH stimulates methylmercury production at the sediment‐water interface and possibly in the aerobic water column. Decreased pH also decreases loss of volatile mercury from lake water and increases mercury binding to particulates in water – factors that may increase methylation at low pH by enhancing the bioavailability of mercury for methylation. In anoxic subsurface sediments, decreased pH decreases the rate of mercury methylation, suggesting that methylmercury formation in the water column and at the sediment‐water interface may be most important in acidified lakes. Sulfate‐reducing bacteria are important mercury methylators in acidified lakes. Whether enhanced sulfate reduction stimulates methylmercury production in low pH lakes is presently unclear, although most of the available data do not support this hypothesis.

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Inability of Fish to Methylate Mercuric Chloride In Vivo

Cited by 31 publications

References 0 publications

Bioaccumulation kinetics and exposure pathways of inorganic mercury and methylmercury in a marine fish, the sweetlips Plectorhinchus gibbosus

Bioaccumulation kinetics and exposure pathways of inorganic mercury and methylmercury in a marine fish, the sweetlips Plectorhinchus gibbosus

Predicting Mercury Concentration in Fish Using Mass Balance Models

Environmental factors affecting the formation of methylmercury in low pH lakes

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