1887

Abstract

Trophozoites of the microaerophilic flagellate parasitic protozoon have only a limited capacity to detoxify O. Thus, when exposed to controlled concentrations of dissolved O >8 μM, they gradually lose their ability to scavenge O. In a washed cell suspension stirred under 10% air in N (equivalent to 25 μM O), inactivation of the O-consuming system was complete after 35 h; during this period accumulation of HO (3 μmol per 10 organisms) and oxidation of cellular thiols to 16% of their initial level occurred. Under 20% air (50 μM O), respiratory inactivation was complete after 15 h, and under air (258 μM O), after 50 min. Loss of O-consuming capacity was accompanied by loss of motility. Use of the fluorogen 2,7-dichlorodihydrofluorescein acetate indicated that intracellular HO is produced at extranuclear sites. Flow cytometric estimation of the plasma membrane electrochemical potentials using bis(1,3-dibutylbarbituric acid) trimethine oxonol, DiBAC(3), showed that values declined from −134 mV to −20 mV after 45 h aeration. Incubation of organisms with 60 μM HO for 10 min gave partial collapse of plasma membrane potential and complete loss of O uptake capacity; motility and viability as assessed by DiBAC(3) exclusion were completely lost after 1 h. Inactivation of the O-consuming system and loss of viability were also observed on exposure to singlet oxygen photochemically generated from rose bengal or toluidine blue.

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2000-12-01
2019-10-19
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References

  1. Aruoma, O. I., Halliwell, B., Gajewski, E. & Dizdaroglu, M. ( 1989; ). Damage to the bases in DNA induced by hydrogen peroxide and ferric ion chelates. J Biol Chem 264, 20509-20512.
    [Google Scholar]
  2. Atkinson, H. J. ( 1980; ). Respiration. In Nematodes as Biological Models , pp. 101-138. Edited by B. H. Zuckerman. London:Academic Press.
  3. Brown, D. M., Upcroft, J. A. & Upcroft, P. ( 1995; ). Free radical detoxification in Giardia duodenalis. Mol Biochem Parasitol 72, 47-56.[CrossRef]
    [Google Scholar]
  4. Craun, G. F. ( 1990; ). Waterborne giardiasis. In Giardiasis. Human Parasitic Disease , pp. 267-290. Edited by E. A. Meyer. Amsterdam:Elsevier.
  5. Edwards, M. R., Gilroy, F. V., Jiminez, M. B. & O’Sullivan, W. J. ( 1989; ). Alanine is a major end product of metabolism by Giardia lamblia: a proton nuclear magnetic resonance study. Mol Biochem Parasitol 37, 19-26.[CrossRef]
    [Google Scholar]
  6. Ellis, J. E., Williams, R., Cole, D., Cammack, R. & Lloyd, D. ( 1993; ). Electron transport components of the parasitic protozoon Giardia lamblia. FEBS Lett 325, 196-200.[CrossRef]
    [Google Scholar]
  7. Ellman, G. L. ( 1959; ). Method for the modification and quantitative detection of thiol groups. Arch Biochem Biophys 82, 70.[CrossRef]
    [Google Scholar]
  8. Emri, M., Balkay, L., Krasznai, Z., Tron, L. & Martin, T. ( 1998; ). Wide applicability of a flow cytometric assay to measure absolute membrane potentials on a millivolt scale. Eur Biophys J 28, 78-83.[CrossRef]
    [Google Scholar]
  9. Halliwell, B. ( 1978; ). Superoxide-dependent formation of hydroxyl radicals in the presence of iron chelates. FEBS Lett 92, 321-326.[CrossRef]
    [Google Scholar]
  10. Halliwell, B. & Gutteridge, J. M. C. (1989). Free Radicals in Biology and Medicine. Oxford: Oxford University Press.
  11. Keister, D. B. ( 1983; ). Axenic culture of Giardia lamblia in TYI-S-33 medium supplemented with bile. Trans R Soc Trop Med Hyg 77, 487-488.[CrossRef]
    [Google Scholar]
  12. Krasznai, Z., Marian, T., Balkay, L., Emri, M. & Tron, L. ( 1995; ). Flow cytometric determination of absolute membrane potential of cells. J Photochem Photobiol B Biol 28, 93-99.[CrossRef]
    [Google Scholar]
  13. Krinsky, N. I. ( 1979; ). Biological roles of singlet oxygen. In Singlet Oxygen , pp. 597-641. Edited by H. H. Wasserman & R. W. Murray. London:Academic Press.
  14. Lamberts, J. J. M. & Neckers, D. C. ( 1985; ). Rose Bengal derivatives as singlet oxygen sensitizers. Tetrahedron 41, 2183-2190.[CrossRef]
    [Google Scholar]
  15. Lloyd, D. & Hayes, A. J. ( 1995; ). Vigour, vitality and viability of microorganisms. FEMS Microbiol Lett 133, 1-7.[CrossRef]
    [Google Scholar]
  16. Lloyd, D., Edwards, S. W., Kristensen, B. & Degn, H. ( 1979; ). The effect of inhibitors on the oxygen kinetics of terminal oxidases of Acanthamoeba castellanii. Biochem J 182, 11-15.
    [Google Scholar]
  17. Lundsgaard, J. & Degn, H. ( 1973; ). A digital gas mixer. IEEE Trans Biomed Eng 20, 384-387.
    [Google Scholar]
  18. Meyer, E. A. ( 1976; ). Giardia lamblia: isolation and axenic cultivation. Exp Parasitol 39, 301-310.
    [Google Scholar]
  19. Ortega, Y. R. & Adam, R. D. ( 1997; ). Giardia: overview and update Clin Infect Dis 25, 545-550.[CrossRef]
    [Google Scholar]
  20. Paget, T., Jarroll, E., Manning, P., Lindmark, D. & Lloyd, D. ( 1989; ). Respiration in the cysts and trophozoites of Giardia muris. J Gen Microbiol 13, 145-154.
    [Google Scholar]
  21. Paget, T., Raynor, M. H., Shipp, D. W. E. & Lloyd, D. ( 1990; ). Giardia lamblia produces alanine anaerobically but not in the presence of oxygen. Mol Biochem Parasitol 42, 63-68.[CrossRef]
    [Google Scholar]
  22. Paget, T., Kelly, M., Jarroll, E., Lindmark, D. & Lloyd, D. ( 1993; ). The effects of oxygen on fermentation in Giardia lamblia. Mol Biochem Parasitol 57, 65-72.[CrossRef]
    [Google Scholar]
  23. Park, J. H., Schofield, P. J. & Edwards, M. R. ( 1995; ). The role of alanine in the acute response of Giardia intestinalis to hypo-osmotic shock. Microbiology 141, 2455-2462.[CrossRef]
    [Google Scholar]
  24. Shukry, S., Zaki, A. M., Dupont, H. L., Shoukry, I., El Tagi, M. & Hamed, S. ( 1986; ). Detection of enteropathogens in fatal and potentially fatal diarrhea in Cairo, Egypt. Clin Microbiol 24, 959-962.
    [Google Scholar]
  25. Smith, H. V., Robertson, L. J., Campbell, A. T. & Girdwood, R. W. A. ( 1995; ). Giardia and giardiasis: what’s in a name. Microbiol Eur 3, 22-29.
    [Google Scholar]
  26. Smith, N. C., Bryant, C. & Boreham, D. F. L. ( 1988; ). Possible roles for pyruvate–ferredoxin oxidoreductase and thiol-dependent peroxidase and reductase activities in resistance to nitroheterocyclic drugs in Giardia intestinalis. Int J Parasitol 18, 991-997.[CrossRef]
    [Google Scholar]
  27. Winiecka-Krusnell, J. & Linder, E. ( 1998; ). Cysticidal effect of chlorine dioxide on Giardia intestinalis cysts. Acta Trop 70, 369-372.[CrossRef]
    [Google Scholar]
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