The liver monooxygenase system of Brazilian freshwater fish

Content of cytochromes b(5) and P-450, and activities of NADPH-cytochrome c (P-450) reductase (NCR) and 7-ethoxyresorufin O-deethylase (EROD) were measured in liver microsomes prepared from two South American endemic fish, Brycon cephalus and Colossoma macropomum, from tilapia, Oreochromis niloticus, and from Swiss mice, Mus musculus. which served as a control. Strong hemoglobin binding to fish liver microsomal membranes (FLM) altered visible spectra of microsomal cytochromes. Consequently, special precautions during FLM preparation, including liver perfusion followed by repeated washing of microsomes, were required in the study of microsomal cytochromes from these fish. FLM from all fish studied here had a significantly lower content of microsomal cytochromes but a similar level of NCR and EROD activities compared to mouse liver microsomes (MLM). Strong response of the monooxygenase system in O. niloticus to water pollution was detected with both specific cytochrome P-450 content and EROD activity increasing sharply. The optical spectra of hemoglobin from B. cephalus and C. macropomum were analyzed and some differences in shape and relative extinction were observed compared to known hemoglobins. (C) 2000 Elsevier Science Inc. All lights reserved.1261293

The liver monooxygenase system of Brazilian freshwater fish

Content of cytochromes b(5) and P-450, and activities of NADPH-cytochrome c (P-450) reductase (NCR) and 7-ethoxyresorufin O-deethylase (EROD) were measured in liver microsomes prepared from two South American endemic fish, Brycon cephalus and Colossoma macropomum, from tilapia, Oreochromis niloticus, and from Swiss mice, Mus musculus. which served as a control. Strong hemoglobin binding to fish liver microsomal membranes (FLM) altered visible spectra of microsomal cytochromes. Consequently, special precautions during FLM preparation, including liver perfusion followed by repeated washing of microsomes, were required in the study of microsomal cytochromes from these fish. FLM from all fish studied here had a significantly lower content of microsomal cytochromes but a similar level of NCR and EROD activities compared to mouse liver microsomes (MLM). Strong response of the monooxygenase system in O. niloticus to water pollution was detected with both specific cytochrome P-450 content and EROD activity increasing sharply. the optical spectra of hemoglobin from B. cephalus and C. macropomum were analyzed and some differences in shape and relative extinction were observed compared to known hemoglobins. (C) 2000 Elsevier Science Inc. All lights reserved.Univ Fed Sao Carlos, Dept Physiol Sci, BR-13565905 Sao Carlos, SP, BrazilUniv São Paulo, Dept Biochem, São Paulo, SP, BrazilState Univ Campinas, UNICAMP, Fac Med Sci, Inst Biol,Dept Biochem, Campinas, SP, BrazilState Univ Campinas, UNICAMP, Fac Med Sci, Dept Clin Pathol, Campinas, SP, BrazilUniversidade Federal de São Paulo, Dept Med, São Paulo, SP, BrazilRussian Acad Sci, Inst Biochem Phys, Moscow, RussiaUniversidade Federal de São Paulo, Dept Med, São Paulo, SP, BrazilWeb of Scienc