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Title: Metallothionein in eels from the Thames Estuary : an indicator of environmental quality
Author: Environment Agency Thames Region
Document Type: Monograph
Metallothioneins (MTs) are cysteine-rich, low molecular weight, metal-binding proteins whose functions include detoxification, storage and metabolism of metals such as cadmium (Cd), copper (Cu), mercury (Hg), silver (Ag) and zinc (Zn). Enhanced synthesis of MT signifies an effort to reduce the toxicity of excessive amounts of metal ions in cells, and as such, MT is potentially important as a specific biochemical indicator of metal pollution. The purpose of this study was to assess the suitability of the MT bio as say in environmental monitoring, using livers of eels Anguilla anguilla, and hence, to establish the bioavailability and toxicological significance o f accumulated metal burdens in eels from the Thames Estuary. Hepatic MT levels and metal concentrations were determined in A. anguilla collected on three occasions during 1998 at sites along the Thames, from Richmond Lock seawards to Blythe Sands, and also from a reference site in SW England. MT was present, inherently, at basal levels of about 2 mg g'1 (dry weight) in livers o f control eels, predominantly in association with Cu and Zn - presumably to regulate requirements for these essential metals. MT concentrations were found to be variable within each eel population but were generally highest (up to 11 mg/g in individual eels) at the more contaminated upper- and mid-estuarine sites in the Thames. There were significant differences in mean hepatic MT levels between eel populations from both Brentford and Kew (inner estuarine sites) and Blythe Sands at the mouth of the estuary. Season, sex, reproductive status and salinity may have influenced MT levels to some extent, although metals were the most significant factor. Hepatic MT levels in all eels sampled were highly correlated with their metal burden (Zn, Cu, Ag and Cd), indicating that MT synthesis is induced in direct response to metal bioavailability - notably to Cu and Ag enrichment in the upper- and mid-estuary.
Publisher: Environment Agency
Publication Date: 2000
Publication Place: Reading
Subject Keywords: MetallothioneinEstuariesBiological indicatorsEnvironmental qualityWater qualityAnguillidaeEcotoxicology
Geographic Keywords: Thames Estuary
Extent: 35
Total file downloads: 38

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