P-glycoprotein-like protein contributes to cadmium resistance in Euglena gracilis

• Published in: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology Vol. 173; no. 7; pp. 559 - 564
• Main Authors: Einicker-Lamas, M, Morales, M M, Miranda, K, Garcia-Abreu, J, Oliveira, A J F, Silva, F L S, Oliveira, M M
• Format: Journal Article
• Language: English
• Published: Germany Springer Nature B.V 01.09.2003
• Subjects: Animals; Antibodies, Monoclonal - pharmacology; Aquatic organisms; ATP Binding Cassette Transporter, Sub-Family B - analysis; ATP Binding Cassette Transporter, Sub-Family B - immunology; ATP Binding Cassette Transporter, Sub-Family B - physiology; Blotting, Western; Cadmium; Cadmium - pharmacology; Cadmium - toxicity; Cell Division - drug effects; Cell Division - physiology; Detoxification; Dose-Response Relationship, Drug; Drug Resistance; Euglena gracilis - drug effects; Euglena gracilis - physiology; Membrane Transport Proteins - physiology; Microscopy, Fluorescence; Proteins; Rhodamine 123 - metabolism; Rhodamine 123 - pharmacology; Survival; Temperature; Verapamil - pharmacology
• ISSN: 0174-1578; 1432-136X
• DOI: 10.1007/s00360-003-0365-5

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.