Influence of Water Temperature on the MXR Activity and P-glycoprotein Expression in the Freshwater Snail, Physa acuta (Draparnaud, 1805)

Abstract

P-glycoprotein (P-gp) mediated multixenobioticresistance (MXR) is a mechanism analogous to multidrug resistance, which has been extensivelycharacterized in mammalian tumours. The expression and function of the MXR mechanism hasbeen demonstrated in numerous aquatic organisms and has been proposed as a biomarker forpollution assessment. A close relationship between thermal stress and MXR response has beenreported in some aquatic organisms. Seasonal studies in freshwater organisms are scarce andconducted mainly in zebra mussel (Dreissena polymorpha), whose presence has not been reportedin South America. The general purpose of the present study was to evaluate seasonal variation of abiomarker, the MXR mechanism, in the worldwide distributed freshwater snail P. acuta. Weanalyzed the in situ influence of temperature on the biomarker response over an 18-month fieldstudy. MXR defence system was evaluated by a combination of functional assays (RB accumulation)and molecular approaches to analyse P-gp expression. The results demonstrated a linear correlationbetween MXR response, at activity and expression level, and water temperature at sample site, in P.acuta snails. The characterization of the MXR system in worldwide distributed species, includingthe study of their seasonal fluctuations, could contribute to the increasing interest to incorporate thisbiomarker to provide an integrated assessment of mussel health status. This work supports thepossible use of P. acuta snails with this purpose and also highlights that the occurrence of variationsin MXR response related to water temperature has to be taken into account in the interpretation ofin situ monitoring studies