engleski

Crowat project: Field-collected mussels Mytilus galloprovincialis (L.) - Variability of metallothionein content between organs and sampling sites

Metallothionein (MT) induction is generally accepted as a biomarker of organism exposure to increased level of metals in aquatic environment. In a preliminary study (2001), the spatial variation of metallothionein content, determined by a spectrophotometric method, was followed in the gills and the digestive gland of the mussel Mytilus galloprovincialis collected at four coastal locations in the Kaštela and Trogir Bay (Croatia) and related to Cd, Cu and Zn content in the heat-treated cytosolic fraction in order to evaluate the applicability of the mussel gill and digestive gland MT as a biomarker in field conditions. In the gills, metallothionein concentrations ranged from 26 to 44 &micro ; ; ; g g-1 wet tissue mass (wm) and were positively correlated with Cu (r=0.76, p<0.001) and Zn concentrations in the heat-treated cytosol fraction (r=0.34). Metallothionein concentrations in the digestive gland were about three times higher than those in the gills (96-119 &micro ; ; ; g/g wm) and showed positive correlations with all three metals measured, especially with Zn (r=0.66, p<0.05). Although spatial trends of MT values were similar for both organs, significant differences between investigated locations in MT content were observed only for gill samples. Additionally, MTs in gill samples were analysed over a period of 4 years. Correlation analysis applied on the data pooled for all four locations revealed that the MT concentrations were highly correlated with the total cytosolic protein concentrations (r=0.64 ; p<0.001), both significantly and negatively correlated with gill mass (r=-0.42 and r=-0.51 for MT and total proteins, respectively). Zn concentrations followed the changes of the MT level. In conclusion, mussel gill MTs can be useful to survey of metal exposure of organisms in coastal areas but the effect of biological variables on MT concentrations should be carefully considered for a correct assessment of differences between stations.

metallothioneins; digestive gland; gills; Mytilus galloprovincialis

nije evidentirano