Molecular responses of the bivalve mollusks from the cooling pond as a model for prediction of contemporary environmental challenges

To reveal a potential combined effect of pollution and continuos warming towards freshwater organisms, the molecular responses of stress and toxicity were compared during two years in the bivalve mollusks Anodonta anatina from the cooling pond of Khmelnytskyi Nuclear Power Plant (N-group) and from the ponds in the forestry (F-group) and agricultural (A-group) areas. Using Classification and Regression Tree (CART) software on the basis of a set of studied markers, characteristics for the distinguishing of N-group were selected. Firstly, it was the constantly elevated level of the vitellogenin-like protein in gonads and hemolymph of male specimens that witness the effect of endocrine disruption. The mussels of N-group demonstrated on oxidative injury with highest values of the Index of inter-seasonal variability for oxidized glutathione and metallothionein-related thiols among three groups, and constantly high level of apoptotic activity in the digestive gland. Remarkably higher levels of copper and cadmium within the tissues were detected in the N-group reflecting the industrial pollution. These metals were preferentially bound to metal-buffering protein metallothionein. A combination of these characteristics demon­strates that stable elevated temperature jointly with industrial pollution caused a partial apoptotic elimination of cells with the nuclear lesions and provoked the exceeding of resistance of stress-related responses and reproduction-related functions in the mussels.