Multiple forms of metallothionein from the digestive gland of naturally occurring and cadmium-exposed mussels, Mytilus galloprovincialis |
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Authors: | Dušica Ivanković Jasenka Pavičić Sonja Kozar Biserka Raspor |
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Institution: | (1) Center for Marine and Environmental Research Zagreb, Ruđer Bošković Institute, Bijenička c. 54, PO Box 180, 10002 Zagreb, Croatia, |
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Abstract: | 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 (G-75 and DEAE A-25),
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.
Electronic Publication |
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Keywords: | Metallothionein Isoforms Mytilus galloprovincialis Digestive gland |
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