The effects of water-borne exposure to benzo[a]pyrene (36 hrs; celite-bound 0.44 mg L-1 B[a]P) on cytochrome P450 (CYP) and superoxide dismutases (SODs) were examined in digestive gland of the blood clam, Scapharca inaequivalvis. B[a]P accumulation and elimination were rapid, with maximum whole-body concentrations of 1.78 ng g-1 wet wt. after 12 hours of treatment, followed by a progressive decline to 0.89 ng g-1 at 36 hours. The presence of B[a]P resulted in an increase in total CYP of digestive gland microsomes from 54 ± 14 to 108 ± 21 pmol mg-1 protein (mean ± SD; p<0.05, 24 hrs). Increases were also seen in microsomal CYP1A1/1A2-immunopositive protein (50.5 kDa app. mol. wt; p<0.05), but not CYP2E1-immunopositive protein (49 kDa app. mol. wt.), indicating a specific response of the former isoform. Exposure to B[a]P produced a steady increase in Mn-SOD digestive gland activity (p<0.01; p<0.05) but no significant change in Cu/Zn-SOD activity. The respective proteins, measured by western blotting, weren’t significant induced after B[a]P exposure. Cu/Zn-SOD and Mn-SOD activities were correlated with total CYP levels (r = 0.96 and 0.63, respectively), indicating a role for CYP in reactive oxygen species (ROS) production during exposure. Both 'NADPH-independent' and NADPH-dependent metabolism of B[a]P by digestive gland microsomes was seen, producing mainly 1,6-, 3,6- and 6,12-diones, with some phenols and 7,8-dihydrodiol; putative protein adducts were also formed. Redox cycling of the diones may also have contributed to ROS production, leading to the increased SOD activities.
M. Monari, O. Cattani, G.P. Serrazanetti, A. Selli, G. Pagliuca, E. Zironi, et al. (2007). Effect of exposure to benzo[a]pyrene on SODs, CYP1A1/1A2- and CYP2E1 immunopositive proteins in the blood clam Scapharca inaequivalvis. MARINE ENVIRONMENTAL RESEARCH, 63, 200-218 [10.1016/j.marenvres.2006.08.004].
Effect of exposure to benzo[a]pyrene on SODs, CYP1A1/1A2- and CYP2E1 immunopositive proteins in the blood clam Scapharca inaequivalvis
MONARI, MARTA;CATTANI, OTELLO;SERRAZANETTI, GIAN PAOLO;SELLI, ANNAROSA;PAGLIUCA, GIAMPIERO;ZIRONI, ELISA;
2007
Abstract
The effects of water-borne exposure to benzo[a]pyrene (36 hrs; celite-bound 0.44 mg L-1 B[a]P) on cytochrome P450 (CYP) and superoxide dismutases (SODs) were examined in digestive gland of the blood clam, Scapharca inaequivalvis. B[a]P accumulation and elimination were rapid, with maximum whole-body concentrations of 1.78 ng g-1 wet wt. after 12 hours of treatment, followed by a progressive decline to 0.89 ng g-1 at 36 hours. The presence of B[a]P resulted in an increase in total CYP of digestive gland microsomes from 54 ± 14 to 108 ± 21 pmol mg-1 protein (mean ± SD; p<0.05, 24 hrs). Increases were also seen in microsomal CYP1A1/1A2-immunopositive protein (50.5 kDa app. mol. wt; p<0.05), but not CYP2E1-immunopositive protein (49 kDa app. mol. wt.), indicating a specific response of the former isoform. Exposure to B[a]P produced a steady increase in Mn-SOD digestive gland activity (p<0.01; p<0.05) but no significant change in Cu/Zn-SOD activity. The respective proteins, measured by western blotting, weren’t significant induced after B[a]P exposure. Cu/Zn-SOD and Mn-SOD activities were correlated with total CYP levels (r = 0.96 and 0.63, respectively), indicating a role for CYP in reactive oxygen species (ROS) production during exposure. Both 'NADPH-independent' and NADPH-dependent metabolism of B[a]P by digestive gland microsomes was seen, producing mainly 1,6-, 3,6- and 6,12-diones, with some phenols and 7,8-dihydrodiol; putative protein adducts were also formed. Redox cycling of the diones may also have contributed to ROS production, leading to the increased SOD activities.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
