engleski

CROWAT project: Metallothionein and metal levels in cytosol of different organs of Mediterranean feral fish species

Heavy metals are important pollutants which represent a serious threat to the aquatic environment, since they are not biodegradable and can accumulate in the sediments and biota. Aquatic organisms have ability to accumulate metals in their tissues to higher levels than those found in the environment, what represents the basis for BIOMONITORING STUDIES. Fish are often used as indicator species of pollutant exposure in the aquatic environment because: fish represent species at the top of the aquatic food chain ; as vertebrates respond strongly to stress conditions ; fish accumulate metals in their tissues The aim of this study was to define association of metallothionein (MT) and metal levels (Zn, Cu (essential), Cd (toxic)) in cytosolic fractions (S50) of feral fish tissue, like liver, kidney, brain and intestine and their dependence on biometric parameters (length, weight, age), as additonal factors which influence MT levels MTs follow the levels of essential metals in liver and kidney, confirming the main role of MT in regulation and metabolism of essential metals. This statement was prooved by MT and essential metal comparison in liver of other native fish species from different locations. Tissue distribution of MT (&micro ; ; g mg-1 proteins) follows Zn (&micro ; ; g ml-1 S50) distribution, which is essential metal and primary inducer of MT: intestine > kidney > liver > brain. Hepatic MT and essential metals, esspecialy Zn, are highly correlated in four different native fish species, benthic and pelagic, no meter on living or location differences proving MT involvement in essential metal homeostasis Toxic metal, Cd, is present at low concentrations without additional influence on cytosolic MT levels, although Cd shows significant accumulation in the cytosol of liver and kidney Changes of MT and cytosolic metal levels with exposure period (fish age, 1-8 years old) indicate to the importance of resolving anthropogenic effect from the natural variability of MT, Zn and Cu caused by morphometric factors• in biomonitoring studies on native fish species using MT as biomarker of metal pollution additional factors, like morphometry, have to be considered as possible causes of MT variability

Metallothioneins (MT); MT/trace metals correlation; Fish age; Fish tissue

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