Metallothionein induction inMytilus edulis exposed to cadmium

Bebianno, Maria João; Langston, W.J.

doi:10.1007/bf01313475

Cited by 114 publications

(50 citation statements)

References 30 publications

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“…I) are similar to the basal levels of MT proposed for marine bivalves (2 mg.g -1 dw) [5]. However, de novo MT production in the whole soft tissues of Cd-exposed clams, although significant at times, was relatively low, in contrast with a 3-to 4-fold MT induction observed in the mussels Mytilus edulis and Mytilus galloprovincialis exposed to the same Cd concentrations [10,11]. Therefore the whole soft tissues were considered unsuitable for following the effects of sublethal Cd contamination in the environment [4].…”

Section: Mt Induction In Laboratory Experimentsmentioning

confidence: 69%

Metallothioneins in the clam Ruditapes decussatus: an overview

Bebianno¹,

Serafim²,

Simes³

2000

Analusis

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The clam R. decussatus is a suspension-feeding bivalve mollusc widely distributed in European and Mediterranean coastal waters. Due to its economic importance it is extensively cultured in many countries, and particularly in Portugal where its production represents > 80 % of total shellfish production. The selection of the clam R. decussatus as a bioindicator was a consequence of its economic importance and the need to use a filter-feeding bivalve to evaluate environmental changes of metal concentrations [1].Like many other bivalves, this species resides in sediments and accumulates metal concentrations reflecting gradients of metal contamination in the surrounding environment [2,3,4]. This suggests that its tissues have mechanisms, related to its filter-feeding habit, that inhibit the toxic effects of these contaminants.Like many other molluscs R. decussatus has evolved a number of subcellular systems for accumulation, regulation and immobilization of metals. These include, among others, the binding of essential and pollutant metals to soluble ligands such as MT. These two-domain molecules are low molecular, heat-stable proteins of non-enzymatic nature that occur mainly in the cytoplasm. They have strong affinity to class B metal cations which enable them to be differentiated from most of the other proteins [5]. The induction of these proteins has, therefore, been proposed as a specific indicator and possible "early warning marker" for the detection of detrimental effects caused by exposure to excess of essential and pollutant metals.MT induction has been detected in the whole soft tissues, gills, digestive gland and remaining tissues of the clam R. decussatus after exposure to essential and toxic metals [4,6] and this paper represents an overview of MT function in this bivalve species. MT induction in laboratory experimentsSeveral laboratory experiments have been carried out to assess MT induction in R. decussatus exposed to sublethal concentrations of cadmium (100 and 400 µg/l), copper (75 µg/l) and lindane (34.5 µg/l) [4,7,6,8].Chromatographic elution profiles of the heat-treated cytosol of the whole soft tissues of unexposed clams revealed that cadmium in this pool (> 80 % of total Cd) was distributed between two cadmium-binding proteins of a molecular weight of around 10,000 and 20,000 Da, respectively, that increased with Cd accumulation. Similarly an increase in the -SH containing proteins (by 70 % compared with unexposed clams), based on differential pulse polarography Similarly the amino acid sequence of the β domain of the MT of the digestive gland of the clam also shows some degree of similarity with the similar MT sequence from mussels and oysters. It is, therefore suggested that there is some degree of similarity in the MT structure among these species.

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Section: Mt Induction In Laboratory Experimentsmentioning

confidence: 69%

Metallothioneins in the clam Ruditapes decussatus: an overview

Bebianno¹,

Serafim²,

Simes³

2000

Analusis

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“…Similarly, in the American oyster, Crassostrea virginica, the monomeric acetylated form of MT (molecular mass 10,000) was predominant in naturally-occurring organisms and in those experimentally exposed to the low Cd level (Roesijadi 1994). In Cd-exposed M. edulis (George et al 1979;Roesijadi and Hall 1981;Köhler and Riisgard 1982;Frazier et al 1985;Bebianno and Langston 1991;Mackay et al 1993), the prevailing part of the total Cd-MT occurred in dimeric form. The proposed concept on differential Cd-mediated expression of specific MT forms was supported by evidence at the gene-expression level (Baršyte et al 1999;Lemoine et al 2000).…”

Section: Discussionmentioning

confidence: 96%

Multiple forms of metallothionein from the digestive gland of naturally occurring and cadmium-exposed mussels, Mytilus galloprovincialis

Ivanković

Pavičić

Kozar

et al. 2002

Helgoland Marine Research

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Polymorphism of metallothioneins in the digestive gland of naturally occurring (control) and experimentally Cd-exposed mussels Mytilus galloprovincialis (200 µg Cd l -1 ; 14 days) was studied by applying the conventional methods of Sephadex column liquid chromatography , and by an electrochemical method (DPASV) for determination of Cd, Zn and Cu concentrations in chromatographic fractions. In both control and Cd-exposed mussels, two distinct molecular mass components of the metallothioneins, monomeric (MT-10) and dimeric (MT-20), were resolved by Sephadex G-75 gel filtration chromatography. In control mussels, the MT-10 component was predominantly expressed as containing markedly higher constitutive levels of Zn (100×) and Cu (10×) than of Cd. Each of these two molecular mass components was further resolved into seven metal-rich peaks by anion-exchange chromatography. In Cd-exposed mussels the larger proportion of Cd was bound to the MT-20 than to the MT-10 component, suggesting that the dimeric component may be considered as a primarily inducible metallothionein. The elution positions of metal-binding maxima of Cd-exposed and control mussels on the respective DEAE chromatographic profiles were comparable. A great similarity in elution positions of Cd maxima between the composite and single-specimen samples was also observed. Our study confirms a high multiplicity of MT forms in mussels from the Mytilus genus not only under the laboratory high-level metal exposure conditions, but also at a natural seawater metal exposure level. The ecotoxicological significance of dimeric and monomeric MT forms, as well as their possible application in the biomonitoring of seawater for trace metals, has been considered.

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“…This element can be tightly bound to low molecular weight proteins (e.g. metallothioneins; Kijhler & Riisgdrd 1982, Bebianno & Langston 1991) that may be assimilated only during intracellular digestion. Assimilation of Zn was more affected by increased ration than other elements, partly because intracellular digestion was affected.…”

Section: Ammentioning

confidence: 99%

Assimilation of trace elements ingested by the mussel Mytilus edulis:effects of algal food abundance

Wang¹,

Fisher²,

Luoma³

1995

Mar. Ecol. Prog. Ser.

156

147

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Pulse-chase feeding and multi-labeled radiotracer techniques were employed to measure the assimilation of 6 trace elements ( l l O m~g , 2 4 1~m , '09Cd, 5 7~o , '$Se and "~n ) from ingested diatoms in the mussel Mytilus e d u l~s feeding at different rates (0.1, 0.49 and 1.5 mg dry wt h-'). Uniformly radiolabeled diatoms Thalassiosira pseudonana were fed to mussels for 0.5 h, and the behavior of the radiotracers in individual mussels was followed for 96 h in a depuration seawater system. Assimilation efficiency (AE) of each element declined with increasing ingestion rate and increased with gut passage time. The importance of extracellular digestion relative to intracellular digestion increased with ingestion activity, which, when coupled with a decline in AE, suggested that extracellular digestion is less efficient in metal absorption. Zn assimilation was most affected by ingestion rate, suggesting that AE may play a role in the physiological regulation of this metal in M. edulis. In an experiment to simulate the effects of an acidic gut, lowered pH (5.5) enhanced the release of elements from intact diatom cells, especially at low particle concentration. These results indicate that both feeding components of the mussel (i.e. gut passage time, digestive partitioning) and metal chemistry (i.e. metal release at lowered pH within the bivalve gut) are responsible for the difference in the assimilation of trace metals at different food quantities observed in mussels.

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Metallothionein induction inMytilus edulis exposed to cadmium

Cited by 114 publications

References 30 publications

Metallothioneins in the clam Ruditapes decussatus: an overview

Metallothioneins in the clam Ruditapes decussatus: an overview

Multiple forms of metallothionein from the digestive gland of naturally occurring and cadmium-exposed mussels, Mytilus galloprovincialis

Assimilation of trace elements ingested by the mussel Mytilus edulis:effects of algal food abundance

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