Induction of hsp70 by the herbicide oxyfluorfen (Goal) in the Egyptian Nile fish, Oreochromis niloticus

This paper deals with the expression of the biomarker hsp70 in the liver an d kidney of the freshwater fish Oreochromis niloticus following exposure to the herbicide oxyfluorfen (Goal). Fishes were exposed to three concentrati ons, the 96-h LC50 (3 mg/L), the 96-h 1/2LC(50) (1.5 mg/L), and the 96-h 1/ 4LC(50) (0.75 mg/L) of oxyfluorfen for 6, 15, and 24 days, respectively, an d samples were taken at three different time periods for each concentration . The livers responded to the herbicide by an induction of the expression o f both the constitutive (hsp75; M-r 75 kDa) and the inducible (hsp73; M-r 7 3 kDa) hsp70 proteins. In kidney, the herbicide induced a time-dependent in crease in the expression of the constitutive hsp70 (hsp75) as well, but the inducible hsp70 (hsp73) required much longer incubation periods to reach m aximal levels (15 and 24 days). Our results suggest that expression of hsp7 0 in fish is a sensitive indicator of cellular responses to herbicide expos ure in the aquatic environment.