Dual capacity for nutrient uptake in tetrahymena importance of the oral uptake system for Fe and Cu uptake
Tóm tắt
We have reported that a mutant ofTetrahymena pyriformis with heat-sensitive development of the oral apparatus can be grown indefinitely without food vacuoles if the medium is supplemented with folinic acid and a mixture of trace metal salts. We report here that the trace metal mixture can be replaced completely and specifically by salts of iron and copper. Fe(II) and Fe(III) are interchangeable. Addition of citrate has proven useful to reduce precipitate formation and improve the reproducibility of growth of the mutant cell. Thus it appears to serve as an Fe buffer. From the increased concentrations of Fe and Cu required to permit good growth of the mutant strain at 37°C, we conclude that the oral uptake system plays a much more important role in the case of these two metals than the surface uptake system. The oral uptake system may facilitate Fe uptake in at least two ways: a) by a mechanical concentration of precipitates affected by the ciliary membranelles surrounding the oral cavity and, b) by lowering of the pH of the food vacuole and thereby releasing Fe from precipitates and from complexes which cannot be transported across the membrane as such. The second factor may also be important in Cu uptake. A specific effect of Mg and Fe uptake or retention in the mutant strain growing without food vacuoles has been detected. The significance of this effect remains unclear. Practical implications of the findings are discussed.
Tài liệu tham khảo
Albert, A.: Selective Toxicity. London: Methuen and Co. Ltd.: New York: John Wiley and Sons, Inc. (1960)
Angelici, R. J.: Stability of coordination compounds. In G. L. Eichorn (ed.) Inorganic Biochemistry, 63–101, Elsevier Scientific Publishing Company, Amsterdam-London-New York (1973)
Byers, B. R.: Iron transport in gram-positive and acid-fast Bacilli. In J. B. Neilands (ed.) Microbial Iron Metabolism, 83–105. Academic Press, New York (1974)
Conner R. L., &S. G. Cline: Iron deficiency and the metabolism ofTetrahymena pyriformis.J. Protozool. 11: 486–491 (1964)
Garibaldi, J. A.: Influence of temperature on the biosynthesis of iron transport compounds bySalmonella typhimurium. J. Bact. 110: 262–265 (1972)
Hutner, S. H.: Inorganic nutrition. Ann. Rev. Microbiol. 26: 313–346 (1972)
Kitchings, J. A.: Food vacuoles. Protoplasmatologia 3: Ch D3b, 1–54 (1956)
Levandowsky, M., &S. H. Hutner: Utilization of Fe3 by the inshore colorless marine dinoflagellateCrypthecodinium cohnii. Ann. N. Y. Acad. Sci. 245: 16–25 (1975)
Mast, S. O.: The food vacuole inParamecium. Biol. Bull. 92: 31–72 (1947)
Neilands, J. B.: Iron and its role in microbial physiology. In J. B. Neilands (ed.) Microbial Iron Metabolism. A Comprehensive Treatise, 3–34. Academic Press, New York-London (1974)
Orias, E., &N. A. Pollock: Heat-sensitive development of the phagocytotic organelle in aTetrahymena mutant. Exptl. Cell. Res. 90: 345–357 (1975)
Rasmussen L., H. E. Buhse, Jr., &K. Groh: Efficiency of filter feeding in two species ofTetrahymena. J. Protozool 22: 110–111 (1975)
Rasmussen, L., &I. Modeweg-Hansen: Cell multiplication inTetrahymena cultures after addition of particulate material. J. Cell Sci. 12: 275–286 (1973)
Rasmussen, L., &E. Orias:Tetrahymena: Growth without phagocytosis. Science 190: 464–465 (1975)
Rosenberg, H., &I. G. Young: Iron transport in the enteric bacteria. In J. B. Neilands (ed.) Microbial Iron Metabolism, 67–82. Academic Press, New York-London (1974)
Sillén, I. G., &A. E. Martell: Stability constants of metal-ion complexes. Special Publication. No. 17 of the Chemical Society, Burlington House, London, W. I. (1964)
Wichterman, R.: The Biology of Paramecium. The Blakiston Co., Inc., New-York-Toronto. (1953)