Some methodological aspects of metallothionein evaluation

Bragigand, Virginie; Berthet, B.

doi:10.1016/s1095-6433(02)00239-8

Cited by 41 publications

(21 citation statements)

References 13 publications

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“…Because MTLP is a cytosolic heat-stable protein, it seems appropriate to consider the relationship between MTLP concentration in a particular type of tissue, and metal concentration in the supernatant obtained after heat-denaturation of the cytosol (S2). However, during heating, the distribution of metals among cytosolic compounds may be modified (Bragigand and Berthet, 2003). Consequently, in the present study, the relationship between MTLP concentration and metal content in the supernatant before heat treatment (S1) was examined.…”

Section: Temporal Variation In Mtlp and Metal Concentrationsmentioning

confidence: 98%

Temporal variations in metallothionein concentration and subcellular distribution of metals in gills and digestive glands of the oyster <i>Crassostrea angulata</i>

2010

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SUMMARY:The metallothionein levels and metal concentrations in whole body, digestive gland and gills of Crassostrea angulata were analyzed in field samples collected from the River Guadalquivir estuary over several years following a mining waste spill upstream. The subcellular distribution of metals was analyzed to determine the mechanisms involved in the detoxification process. The highest metallothionein levels were reported in the digestive gland shortly after the mining contamination event. In this organ, metals are stored preferentially in the non-cytosolic fraction when increased bioaccumulation takes place. In the cytosol of the gills, metals are associated with metallothionein, whereas in the digestive gland, the distribution of metals between metallothioneins and high molecular weight proteins is similar. Metallothionein variation cannot be explained by metals alone; other abiotic factors must be taken into account. In order to use metallothionein as a metal exposure biomarker in field studies, natural variability needs to be taken into account for the correct interpretation of results.Keywords: metallothionein, metals, subcellular distribution, River Guadalquivir estuary, mining accident, Crassostrea angulata.RESUMEN: Variación temporal de la concentración de metalotioneínas y distribución subcelular de metales en branquias y glándula digestiva del ostron Crassostrea angulata. -Los niveles de metalotioneínas y las concentración de metales en cuerpo total, glándula digestiva y branquias de Crassostrea angulata han sido analizados en muestras de campo recogidas en el estuario del Guadalquivir durante varios años después de un accidente minero. La distribución subcelular de metales se analizó con el fin de conocer los mecanismos implicados en los procesos de detoxificación. Los niveles más elevados de metalotioneínas se hallaron en la glándula digestiva de muestras recogidas después del accidente minero. En este órgano, los metales se almacenan preferencialmente en la fracción no citosólica cuando la bioacumulación aumenta. En el citosol de las branquias, los metales se hallan asociados a las metalotioneínas, mientras que en la glándula digestiva, éstos se encuentran distribuidos de manera similar entre las metalotioneínas y las proteínas de alto peso molecular. La variación de la concentración de metalotioneínas no puede ser explicada sólo en base a las concentraciones de metales, y otros factores abióticos pueden ser responsables del porcentaje de varianza no explicado. Por ello, el empleo de la concentración de metalotioneína como biomarcador de exposición de metales en Crassostrea angulata debe ser considerado con precaución y el conocimiento de la variabilidad natural deber ser tenido en cuenta para una correcta interpretación de los resultados.Palabras clave: metalotioneinas, metales, distribución subcelular, estuario del río Guadalquivir, accidente minero, Crassostrea angulata. Scientia Marina 74S1

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Section: Temporal Variation In Mtlp and Metal Concentrationsmentioning

confidence: 98%

Temporal variations in metallothionein concentration and subcellular distribution of metals in gills and digestive glands of the oyster <i>Crassostrea angulata</i>

2010

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“…compared to other crustaceans may be due to enhanced storage of Cd to MT and/or low ion permeability coincident with a life history involving hypersaline conditions (Eisler 1971, del Ramo et al 1995, Rainbow 1998, Martínez et al 1999, Sarabia et al 2002b, Van Stappen 2002. The association between the quantification of Cd bound to MT and Cd detoxification/tolerance must be interpreted with caution, however, since metal enrichment of the HSP fraction may also be an artifact of heatdenaturation (Bragigand & Berthet 2003). The only other subcellular fraction containing a substantial portion of Cd in controls was cellular debris (~40%).…”

Section: Accumulation and Subcellular Distribution Of CD (Cd-series; mentioning

confidence: 99%

Importance of metal-binding proteins in the partitioning of Cd and Zn as trophically available metal (TAM) in the brine shrimp Artemia franciscana

Seebaugh¹,

Wallace²

2004

Mar. Ecol. Prog. Ser.

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Studies have shown that the trophic transfer of certain metals in aquatic systems may be controlled by the internal distribution of metal within prey and that this distribution may be influenced by detoxification mechanisms (i.e. metals bound to metal-binding proteins [metallothioneins, MT] may be more available to predators than metals associated with insoluble cellular constituents). The purpose of this investigation was to examine the interactive effects of Cd and Zn exposure on the accumulation and subcellular distribution of these metals in the brine shrimp Artemia franciscana. Particular attention was given to the partitioning of metals to a subcellular compartment containing heat-stable proteins (HSP) (e.g. MT), heat-denatured proteins (HDP) (e.g. 'enzymes') and organelles, here considered as trophically available metal (TAM). Adult A. franciscana were exposed for 3 d to Cd (control, 1, 89 or 445 µM and Zn-control) or Zn (control, 1, 89 or 445 µM and Cd-control) through solution using radioisotopes ( 109 Cd and 65 Zn) as tracers of stable metals. Following exposure, various operationally defined subcellular fractions were obtained. Increased binding of Cd to HSP resulted in increased partitioning of Cd to the TAM compartment (i.e. TAM-Cd% increased from 57 to 80% over the range of Cd exposures). This increase in TAM was greater than proportional at the 1 µM Cd exposure concentration and could result in a 'bioenhancement' of Cd trophic transfer to predators. Exposure to elevated concentrations of Cd (89 and 445 µM) also resulted in a ~50% suppression in Zn accumulation by A. franciscana. Upon increasing Zn exposure, a shift in the subcellular partitioning of Zn among TAM fractions (from HSP to HDP and organelles) maintained a TAM-Zn% of ~65%. As a verification of the TAM concept, a direct relationship was observed between the partitioning of Cd and Zn to the TAM compartment of A. franciscana exposed to the Cd-control/Zn-control treatment and absorption of these metals by the grass shrimp Palaemonetes pugio.

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“…After tissue homogenization, homogenates were separated sequentially into five operationally defined subcellular fractions [33][34][35][36]: cellular debris (cell membrane, nuclei, connective tissue, and intact cells), metal-rich granules (non-biologically active fraction), organelles (mitochondria, lysosomes, microsomes), MTLPs, and heat-denatured proteins (cytosol enzymes). Gel-permeation chromatographic separation to further purify the MTLPs was not necessary because only a small number of biological macromolecules were included in the heat-stable cytosolic supernatants in the marine invertebrates [37,38].…”

Section: Subcellular Fractionationmentioning

confidence: 99%

Differential roles of metallothionein‐like proteins in cadmium uptake and elimination by the scallop Chlamys nobilis

Liu

Wang

2011

Enviro Toxic and Chemistry

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Metallothionein-like proteins (MTLPs) are important inducible ligands for Cd detoxification, but whether MTLPs are involved in Cd bioaccumulation remains unclear. The present study investigated the potential interrelationships between MTLP turnover and Cd biokinetics in the scallop Chlamys nobilis with or without dissolved Cd pre-exposure. After Cd pre-exposure, increased synthesis rate and standing stock concentration of MTLPs as well as increased dissolved Cd uptake rate, were found in C. nobilis. However, the level of newly sequestrated Cd by MTLPs in the pre-exposed scallops was similar to that of the controls, indicating that MTLPs had no effect on Cd uptake from the dissolved phase. Instead, Cd uptake rate was positively related to the Cd binding rate of cellular debris and organelles. In addition, no significant difference was observed in the Cd dietary assimilation efficiency of the scallops, showing that MTLPs played a minimal role in Cd uptake from the dietary phase. Conversely, the Cd efflux rate constant decreased by 68 to 75% in the pre-exposed scallops in comparison with that in the control. Correspondingly, progressive elevations of MTLP-bound Cd and standing stock MTLP concentration were observed in the pre-exposed individuals during the Cd elimination period. In the pre-exposed scallops, the faster de novo MTLP synthesis could remobilize and recycle more Cd from other intracellular pools, effectively reducing the Cd elimination rate. The present study thus showed the differential roles of MTLPs in Cd uptake and elimination in the bivalves.

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Some methodological aspects of metallothionein evaluation

Cited by 41 publications

References 13 publications

Temporal variations in metallothionein concentration and subcellular distribution of metals in gills and digestive glands of the oyster <i>Crassostrea angulata</i>

Temporal variations in metallothionein concentration and subcellular distribution of metals in gills and digestive glands of the oyster <i>Crassostrea angulata</i>

Importance of metal-binding proteins in the partitioning of Cd and Zn as trophically available metal (TAM) in the brine shrimp Artemia franciscana

Differential roles of metallothionein‐like proteins in cadmium uptake and elimination by the scallop Chlamys nobilis

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