Seasonal variation of MXR and stress proteins in the common mussel, Mytilus galloprovincialis.

The accumulation of heat-shock HSP70 and MXR proteins in the digestive gland and gills respectively of the mussel (Mytilus galloprovincialis) has been examined in individuals collected monthly during 1 year from the mariculture areas located in the Ebro Delta (NW Spain). Both proteins were visualised and semi-quantified by western blot using commercially available monoclonal antibodies and subsequent image analysis. Two HSP-related bands of Mr 72 and 78 kDa and two MXR proteins of Mr 230 and 130 kDa were detected and their seasonal variations in expression levels recorded. A significant correlation between HSP70 and MXR expression was obtained, the maximum protein accumulation being detected during the summer period. These two parameters were also significantly correlated to water temperature at sample sites. These results suggest either a direct role of temperature in protein expression or an indirect role driven by food availability and growth.