Expression of P-glycoprotein in the gills of oysters, Crassostrea virginica: seasonal and pollutant related effects

The expression of p-glycoprotein (p-gp) in aquatic organisms has been propo sed as a biomarker of pollution exposure. Previous research has provided ev idence that p-gp is inducible by organic xenobiotics and that p-gp is overe xpressed in mussels from degraded areas. However, seasonal changes in expre ssion at polluted sites has not been described previously. The purposes of these studies were to evaluate the expression of p-gp in polluted and unpol luted sites in oysters (Crassostrea virginica) and to determine if there we re seasonal differences. P-gp expression and total protein concentrations w ere measured seasonally in the gills of southeastern oysters, Crassostrea v irginica, at degraded and undegraded sites in Charleston Harbor, South Caro lina, USA. At all sites, p-gp expression was generally higher during the wa rmer months and lower in the colder months. Polluted sites tended to show a decrease in p-gp expression in June and September, suggesting that p-gp in hibition may have occurred. P-gp expression was not significantly related t o specific classes of sediment contaminants or to overall sediment contamin ant loading. Total gill protein concentrations at all sites were lower duri ng the warmer months and higher during the colder months. In general, all s ites tended to show decreased total gill protein concentrations when compar ed to the control site. Total protein concentrations were significantly rel ated to water temperature, specific classes of sediment contaminants and ov erall sediment contaminant loads, but there was no relationship with salini ty. (C) 2001 Elsevier Science B.V. All rights reserved.