title: P-glycoprotein-like protein contributes to cadmium resistance in Euglena gracilis.
abstract: Selective pressures from polluted environments have led to the development of resistance systems in aquatic organisms. Using different techniques, this study examined a cadmium defense mechanism of the freshwater unicellular protozoa Euglena gracilis, and found it to be an efflux pump similar to the multidrug resistance P-glycoprotein. Cd(2+)-treated E. gracilis were able to extrude Rhodamine 123 at 21 degrees C, but not at 4 degrees C. Furthermore, verapamil, a P-glycoprotein modulator, partially blocked the efflux process (at 21 degrees C), and enhanced the Cd(2+) toxic effects on these cells. Western immunoblots of cell lysates, using the anti-P-glycoprotein antibody JSB-1, revealed a 120-KDa protein, which was expressed, in high amounts on Cd(2+)-exposed cells (74% above the control values). Moreover, cells treated with JSB-1 became more sensitive to the harmful effects of cadmium, showing a decreased survival rate. Taken together, these results suggest that a MDR phenotype has evolved in Euglena as one of the mechanisms for cadmium detoxification.
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590, Rio de Janeiro, Brazil. einicker@biof.ufrj.br
authors.forename: M
authors.initials: M
authors.lastname: Einicker-Lamas
authors.forename: M M
authors.initials: MM
authors.lastname: Morales
authors.forename: K
authors.initials: K
authors.lastname: Miranda
authors.forename: J
authors.initials: J
authors.lastname: Garcia-Abreu
authors.forename: A J F
authors.initials: AJ
authors.lastname: Oliveira
authors.forename: F L S
authors.initials: FL
authors.lastname: Silva
authors.forename: M M
authors.initials: MM
authors.lastname: Oliveira
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000032:analysis / Q000276:immunology / Q000502:physiology*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015153:Blotting, Western; D002104:Cadmium / Q000494:pharmacology* / Q000633:toxicity; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D005056:Euglena gracilis / Q000187:drug effects / Q000502:physiology*; D026901:Membrane Transport Proteins / Q000502:physiology; D008856:Microscopy, Fluorescence; D020112:Rhodamine 123 / Q000378:metabolism / Q000494:pharmacology; D013696:Temperature; D014700:Verapamil / Q000494:pharmacology
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D000911:Antibodies, Monoclonal; D026901:Membrane Transport Proteins; D002104:Cadmium; D020112:Rhodamine 123; D014700:Verapamil