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

Abstract

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

Biomarkers of environmental stress in gills of ribbed mussel Aulacomya atra atra (Nuevo Gulf, Northern Patagonia)

“…In aquatic invertebrates, MT play an important role in many physiological processes including homeostasis, protection against trace metals and oxidant damage, metabolic regulation, sequestration and/or redox control (Mao et al, 2012). Although several studies with bivalves have demonstrated positive correlations between MT measured in gills and metal content (Géret et al, 2002;Khati et al, 2012;Trombini et al, 2010), our results showed no relationship between MT and metal concentrations, except for Al. This lack of correlation has been previously reported for Mytilus galloprovincialis (Fernández et al, 2010) and also for mussel Mytilus edulis (Geffard et al, 2005).…”

Temporal and spatial distribution of semicarbazide in western Laizhou Bay

“…In this study, MT content in oysters from XZ was significantly higher than that from other sites. Several studies have found that MT content had positive correlations with metal concentrations in bivalves (Trombini et al, 2010;Khati et al, 2012). Furthermore, Cd, Cu and Zn were also regarded as an inducer of MT (Viarengo et al, 1997;Marigomez et al, 2002), which was consistent with the high levels of Cd, Cu and Zn at XZ site.…”

Assessment of stress biomarkers responses in mantle and adductor muscles of Mactra stultorum following lead exposure

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