Internal Metal Sequestration and Its Ecotoxicological Relevance:  A Review

Vijver, Martina G.; Gestel, Cornelis A.M. van; Lanno, Roman P.; Straalen, Nico M. van; Peijnenburg, Willie J.G.M.

doi:10.1021/es040354g

Cited by 400 publications

(286 citation statements)

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“…2, c) whereby As is thought to be sequestered via binding with sulphur-rich metallothionein within the chloragogenous tissue 3,17,31 allowing the continued 15 accumulation of inorganic As (Fig. 3a) in a form that is not biologically reactive 6 .…”

Section: Discussionmentioning

confidence: 99%

Arsenic biotransformation in earthworms from contaminated soils

et al. 2009

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Two species of arsenic (As) resistant earthworm, Lumbricus rubellus and Dendrodrillus rubidus, their host soils and soil excretions (casts) were collected from 23 locations at a former As mine in 5 Devon, UK. Total As concentrations, measured by ICP-MS, ranged from 255 to 13,080 mg kg -1 in soils, 11 to 877 mg kg -1 in earthworms and 284 to 4221 mg kg -1 in earthworm casts from a subsample of 10 of the 23 investigated sites. The samples were also measured for As speciation using HPLC-ICP-MS to investigate potential As biotransformation pathways. Inorganic arsenate (As V ) and arsenite (As III ) were the only species detected in the soil. As V and As III were also the dominant 10 species found in the earthworms and cast material together with lower proportions of the organic species methylarsonate (MA V ), dimethylarsinate (DMA V ), arsenobetaine (AB) and three arsenosugars. Whilst the inorganic As content of the earthworms increased with increasing As body burden, the concentration of organic species remained relatively constant. These results suggest that the biotransformation of inorganic arsenic to organic species does not contribute to As 15 resistance in the sampled earthworm populations. Quantification of As speciation in the soil, earthworms and cast material allows a more comprehensive pathway for the formation of AB in earthworms to be elucidated. Received (in XXX, IntroductionThe chemistry of As in environmental and biological systems is complex. Whilst inorganic As species are the most prevalent in abiotic environments, the uptake of inorganic As 25 by living organisms can lead to the synthesis of organic As species 1 through biotransformation. The ubiquitous, epegeic earthworm species L. rubellus and D. rubidus are known to inhabit soils highly contaminated with As at the former mine site of Devon Great Consols (DGC), UK. [2][3][4][5] These earthworms 30 are clearly resistant to As toxicity and several potential coping mechanisms have been proposed, yet the underlying mechanism behind this resistance is unknown. Behavioural adaptation, whereby the earthworm avoids contact with the contaminant, 4 is unlikely as earthworms from DGC are known 35 to have elevated As body burdens. 2,4, 5 The biotransformation of highly toxic inorganic As to the less toxic organic species arsenobetaine (AB) has been speculated as a mode of mitigating As toxicity in DGC earthworms. 2,4 An alternative mechanism involves the sequestration of arsenic in the 40 metallothionein-rich chloragogenous tissue which separates the intestine from the coelomic cavity. 3 With this mechanism it is proposed that inorganic As III binds to the sulphur-rich metallothionein thereby sequestering ingested As in a form that is not biologically reactive. The study of As speciation can provide important information on As biotransformation and toxicity and to date a multitude of organic As species have been identified. 7 The occurrence of organic As species and their biotransformation pathways are well documented in marine organisms such as crus...

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Section: Discussionmentioning

confidence: 99%

Arsenic biotransformation in earthworms from contaminated soils

et al. 2009

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“…Uranium accumulation in organisms can be expressed as the quantity of uranium responsible for the observed potential effect. Uranium is also noted to accumulate in the cytosol fraction [11,14], and the cytosol fraction can be separated into several sub fractions (because of the presence of proteins that can be denatured by exposure to heat as well as heat-stable proteins) to better identify the toxic fraction [15,51]. Further developments based on the subcellular distribution in metal rich granules (MRG) or in proteins of the cytosolic fraction, could be addressed by incorporating newly acquired findings on uptake mechanisms and potential toxic effects.…”

Section: Feeding Behaviormentioning

confidence: 99%

“…Taking into account the high concentration in HP, clearly uranium exposure could lead to significant effects in these organs, as demonstrated by Al Kaddissi et al [23] for another crayfish species, P. clarkii. Trophic transfer therefore represents a significant source of uranium accumulation and could lead to the same biological effects as that for direct exposure, considering that a threshold of internalization is linked to toxic effects [11].…”

Section: Feeding Behaviormentioning

confidence: 99%

“…This is referred to as the critical body residues approach [7,[10][11][12][13][14], which focuses on the characterization of metal distribution in organisms. Even if the relationship between bioaccumulation expressed by the metal-available fraction and toxicity remains complex [15][16][17], toxicity is now seen to depend partly on the biological model, the metal, and more accurately, chemical binding of the metal within cells [17,18].…”

Section: Introductionmentioning

confidence: 99%

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Relative importance of direct and trophic uranium exposures in the crayfish Orconectes limosus: Implication for predicting uranium bioaccumulation and its associated toxicity

Simon

Floriani

Camilleri

et al. 2012

Enviro Toxic and Chemistry

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Abstract-Pollutants that occur at sublethal concentrations in the environment may lead to chronic exposure in aquatic organisms. If these pollutants bioaccumulate, then organisms higher in the food chain may also be at risk. Increased attention has thus been focused on the relative importance of dietary uptake, but additional knowledge of the cellular distribution of metals after dietary exposure is required to assess the potential toxicity. The authors address concerns relating to increasing uranium (U) concentrations (from 12 mg/L to 2 mg/L) in the freshwater ecosystem caused by anthropogenic activities. The objective of the present study is to compare uranium bioaccumulation levels in tissues and in the subcellular environment. The authors focused on the cytosol fraction and its microlocalization (TEM-EDX) in the gills and the hepatopancreas (HP) of the crayfish Orconectes limosus after 10 d of direct exposure (at concentrations of 20, 100, and 500 mg/L) and five trophic exposure treatments (at concentrations from 1 to 20 mg/g). Results indicated that adsorption of uranium on the cuticle represents the main contribution of total uranium accumulation to the animal. Accumulation in the gills should be considered only as a marker of waterborne uranium exposure. Accumulation in the HP after trophic environmental exposure conditions was higher (18.9 AE 3.8 mg/g) than after direct exposure. Moreover, no significant difference in the subcellular distribution of uranium (50%) in HP was observed between animals that had been exposed to both types of treatment. A potential toxic effect after uranium accumulation could therefore exist after trophic exposure. This confirms the need to focus further studies on the metal (uranium) risk assessment. Environ. Toxicol. Chem. 2013;32:410-416. # 2012 SETAC

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“…Binding of metals to cytosolic ligands represents the important way by which the body removes excess metals from the vicinity of important biological molecules, thus preventing their toxic effects (Vijver et al, 2004). Therefore, it is very important to determine which cytosolic biomolecules bind metals specifically in normal metabolism as well as whether the same biomolecules are involved in binding processes under metal exposure conditions.…”

Section: Discussionmentioning

confidence: 99%