Journal of Biosciences

, Volume 6, Issue 4, pp 475–489 | Cite as

Differentiation of pathogenic amoebae: encystation and excystation ofAcanthamoeba culbertsoni — A model

  • C. R. Krishna Murti
  • O. P. Shukla


Differentiation into dormant cysts and vegetative trophozoites is an inherent character intimately associated with the life cycle and infectivity of pathogenic amoebae. In the case of human intestinal amoebiasis encystation and excystation are of immediate relevance to the process of transmission of the disease from healthy carriers to susceptible individuals. Using a pathogenic free living amoebaAcanthamoeba culbertsoni as a model, considerable progress has been achieved in understanding the mechanism and control of the process of differentiation. The turnover of the regulatory molecule cyclic 3: ’5′ adenosine monophosphate is responsible for triggering the process of encystation. Amoebae bind effector molecules such as biogenic amines to a membrane localized receptor which itself resembles the β-adrenergic receptor of mammalian organisms. The activation of adenylate cyclase or inhibition of cyclic AMP phosphodiesterase maintain the dynamic intracellular cyclic AMP. The cytosol fraction of amoebae has a cyclic AMP binding protein. During encystation, enzymes needed for synthesis of cellulose and glycoproteins are induced. Control is exercised at transcriptional level and the process is subject to catabolic repression.

Excystation of mature amoebic cysts is mediated by glutamic acid and certain other amino acids by an as yet unelucidated mechanism. During excystation there is dormancy break, induction of deploymerizing enzymesviz. two proteases, a cellulase and a chitinase. The empty cysts or cyst walls are digested by these enzymes and their break down products are used for cellular growth. By invoking a flip-flop mechanism of repression and derepression some plausible explanation can be offered for the cascade of biochemical events that sets in when amoeba is ‘turned on’ to encystation or excystation.


Amoeba encystation excystation cyclic AMP 


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  1. Achar, S. B. and Weissman, R. A. (1980)Biochim. Biophys. Acta,629, 225.PubMedGoogle Scholar
  2. Balamuth, W. (1951)J. Infect. Dis.,88, 230.PubMedGoogle Scholar
  3. Balamuth, W. and Weiboldt, M. L. (1951)Am. J. Trop. Med.,31, 192.Google Scholar
  4. Band, R. N. (1963)J. Protozool.,19, 101.Google Scholar
  5. Bhagwandeen, S. B., Carter, R. F., Naik, K. G. and Levity, D. (1975):J. Clin. Pathol.,63, 483.Google Scholar
  6. Bowers and Korn (1969)J. Cell Biol.,41; 786.PubMedCrossRefGoogle Scholar
  7. Batt, C. G. (1966)N. Engl. J. Med.,274, 1473.CrossRefGoogle Scholar
  8. Carter, R. (1968)J. Pathol. Bacteriol.,96, 1.PubMedCrossRefGoogle Scholar
  9. Carter, R. F., Cullity, G. J., Ojeda, V. J., Silberstein, P., Willaert, R. (1981)Pathology,13, 51.PubMedCrossRefGoogle Scholar
  10. Casemere, D. P. (1969)J. Clin. Pathol.,22, 254.CrossRefGoogle Scholar
  11. Carva, L. and Novak, K. (1968)Science,160, 92.CrossRefGoogle Scholar
  12. Chang, R. S., Geyer, R. P. and Andrus, S. B. (1962).J. Exp. Med. 115, 405.Google Scholar
  13. Chambers, J. A. and Thompson, J. E. (1972)Exp. Cell. Res.,73, 415.PubMedCrossRefGoogle Scholar
  14. Culbertson, C. G. (1961)Am. J. Clin. Pathol.,35, 195.PubMedGoogle Scholar
  15. Culbertson, C. G., Emsminger, P. W. and Oerton, W. M. (1966)Am. J. Clin. Pathol.,46, 305.PubMedGoogle Scholar
  16. Diamond, L. S. (1968a)J. Parasitol.,54, 715.PubMedCrossRefGoogle Scholar
  17. Diamond, L. S. (1968b)J. Parasitol.,54, 1047.PubMedCrossRefGoogle Scholar
  18. Dobell, G. and Neal, R. A. (1952)Parasitology,42, 16PubMedCrossRefGoogle Scholar
  19. Duma, R. (1972)Cut. Rev. Clin. Lab. Sci.,3, 163.CrossRefGoogle Scholar
  20. Duma, R. (1980)Trends in Neuro Sciences,3, 78.CrossRefGoogle Scholar
  21. Eldridge, A. and Tobin, J. (1967)Br. Med. J., 1, 29.CrossRefGoogle Scholar
  22. Freedman, L. (1958)South Afr. Med. J.,32, 797.Google Scholar
  23. Fowler, M. and Carter, R. F. (1965)Br. Med. J.,2, 740.PubMedCrossRefGoogle Scholar
  24. Griffiths, R. J. and Hughes, D. E. (1968)J. Protozoal, 15, 673.Google Scholar
  25. Griffin, J. L. (1978) inParasitic Protozoa (ed. J. P. Krejer) (New York: Acad Press) p. 507.Google Scholar
  26. Grunnet, M. L., Cannon, G. H. and Kushner, J. P. (1981)Neurology, 31, 174.PubMedGoogle Scholar
  27. Jager, B. and Stamn, W. (1972)Lancet, 2, 1343.PubMedCrossRefGoogle Scholar
  28. Jahnes, W. G., Fullmer, H. M. and Li, C. P. (1957)Proc. Soc. Exp. Biol. Med.,96, 487.Google Scholar
  29. Jonckheere, J. F. de (1981)J. Protozool.,28, 56.PubMedGoogle Scholar
  30. Kaushal, D. C. (1976)Chemical studies on the excystment of amoeba, Ph.D. Thesis, University of Kanpur, Kanpur.Google Scholar
  31. Kaushal, D C and Shukla, O. P. (1975)Indian J. Exp. Biol.,13, 242.Google Scholar
  32. Kaushal, D C and Shukla, O. P. (1976)Indian J. Exp. Biol.,14, 498.PubMedGoogle Scholar
  33. Kaushal, D. C. and Shukla, O. P. (1977a)Indian J. Exp. Biol. 15, 542.PubMedGoogle Scholar
  34. Kaushal, D. C. and Shukla, O. P. (1977b)J. Gen. Microbiol.,98, 117.PubMedGoogle Scholar
  35. Kaushal, D. C. and Shukla, O. P. (1978a)Indian J. Exp. Biol., 16,1104.PubMedGoogle Scholar
  36. Kaushal, D. C. and Shukla, O. P, (1978b)Indian J. Exp. Biol.,16, 1102.PubMedGoogle Scholar
  37. Kaushal, D. C. and Shukla, O. P. (1978c)Indian J. Parasitol.,2, 133.Google Scholar
  38. Kaushal, D. C., Verma, A. K. and Raizada, M. K. (1976)Curr. Sci. 45, 181.Google Scholar
  39. Kenny, M. (1971)Health Lab. Sci.,8, 5.Google Scholar
  40. Krishna Murti, C. R. (1971)Cur. Sci. 40, 589.Google Scholar
  41. Krishna Murti, C. R. (1973)Biochem. Soc. Trans.,1, 1152.Google Scholar
  42. Krishna Murti, C. R. (1975)Indian J. Med. Res.,63, 757.Google Scholar
  43. Matter, F. A. and Byers, T. J. (1971)J. Cell Biol.,49, 507.CrossRefGoogle Scholar
  44. Me Connochie E. W. (1969)Parasitology, 59, 41.CrossRefGoogle Scholar
  45. Mitra, S. (1975)Biochemical studies on Entamoeba histolytica in relation to encystation, Ph.D. Thesis, University of Nagpur, Nagpur.Google Scholar
  46. Mitra, S. and Krishna Murti, C. R. (1978)Proc. Indian Acad. Sci.,B87, 9.Google Scholar
  47. Moore, A. E. and Hlinka, J. (1968)J. Natl. Cancer Inst.,40, 569.PubMedGoogle Scholar
  48. Nagington, J., Watson, P. G., Play Fair, T. J., Me Gill, J., Jones, B. R. and McSteel, A. D. (1974)Lancet, 2, 1537.CrossRefGoogle Scholar
  49. Neal, R. A. (1960)Parasitology,50, 531.PubMedCrossRefGoogle Scholar
  50. Nef, R. J. (1957)J. Protozool.,4, 176Google Scholar
  51. Nef, R. J. and Neff, R. H. (1969)Symp. Soc. Exp. Biol.,23, 51.Google Scholar
  52. Neff, R. J., Ray, S. A., Benton, W. F. and Wilborn, M. (1964) inMethods in Cell Physiology, (ed. D. M. Prescott), (London and New York: Acad. Press) vol. 1, p. 55.Google Scholar
  53. Peloux, Y., Nicolas, A., Reyron, A. and Beurlet, J. (1974)Pathol. Biol.,22, 587.PubMedGoogle Scholar
  54. Raizada, M. K. (1972)Chemical studies on the encystment of amoeba, Ph.D. Thesis, University of Kanpur, Kanpur.Google Scholar
  55. Raizada, M. K. and Krishna Murti, C. R. (1971a).J. Protozool,18, 115.PubMedGoogle Scholar
  56. Raizada, M. K. and Krishna Murti, C. R. (1971b)Symp. Cellular Growth and Differentiation, BARC, Bombay, 1971, p. 426.Google Scholar
  57. Raizada, M. K. and Krishna Murti, C. R. (1972a)J. Cell Biol. 52, 743.PubMedCrossRefGoogle Scholar
  58. Raizada, M. K. and Krishna Murti, C. R. (1972b)J. Protozool.,19, 691.PubMedGoogle Scholar
  59. Raizada, M. K., Saxena, K. C. and Krishna Murti, C. R. (1972)J. Protozool, 19, 98.PubMedGoogle Scholar
  60. Raizada, M. K. and Krishna Murti, C. R. (1973)Cur. Sci.,42, 202.Google Scholar
  61. Rivera, F., Galvan, M., Robles, E., Leal, P., Gonzates, L. and Lacy, A. M. (1981)J. Protozool.,28, 54.PubMedGoogle Scholar
  62. Robison, G. A., Butcher, R. W. and Sutherland, E. W. (1971)Cyclic AMP (New York: Acad. Press) p. 84.Google Scholar
  63. Robert, V. B. and Rorke, L. B. (1973)Ann. Int. Med.,79, 174.PubMedGoogle Scholar
  64. Rudick, V. L. and Weisman, R. A. (1973)Nature (London),244, 220.CrossRefGoogle Scholar
  65. Singh, B. N. (1965) inPathogenic and Non-Pathogenic Amoebae (London and Basingotoke: The Macmillan Press Ltd).Google Scholar
  66. Singh, B. N. and Das, S. R. (1970)Philos. Trans. R. Soc. London, Ser. B.,236, 405.CrossRefGoogle Scholar
  67. Srivastava, D. K. (1982) Ph.D. Thesis, University of Kanpur, Kanpur.Google Scholar
  68. Srivastava, D. K. and Shukla, O. P. (1982)Indian J. Parasitol.,6, 211.Google Scholar
  69. Srivastava, D. K. and Shukfa, O. P. (1983a)Indian J. Exp. Biol.,21, 440.PubMedGoogle Scholar
  70. Srivastava, D. K. and Shukla, O. P. (1983b)Indian J. Exp. Biol.,21, 444.PubMedGoogle Scholar
  71. Stevens, A. R. and Pachler, P. F. (1973)J. Cell Biol.,57, 525.PubMedCrossRefGoogle Scholar
  72. Sussman, M. (1965)Ann. Rev. Microbiol.,19, 59.CrossRefGoogle Scholar
  73. Trager, W. (1963)J. Protozool.,14, 114.Google Scholar
  74. Verma, A. K. (1975)Chemical studies on the differentiation of free living amoeba, Ph.D. Thesis, University of Kanpur, Kanpur, India.Google Scholar
  75. Verma, A. K. and Krishna Murti, C. R. (1975)Biochem. Pharmacol.,24, 1133.CrossRefGoogle Scholar
  76. Verma, A. K., Krishna Murti, C. R. (1976a)Indian J. Biochem. Biophys.,13, 247.Google Scholar
  77. Verma, A. K. and Krishna Murti, C. R. (1976b)Indian J. Biochem. Biopkys.,13, 75.Google Scholar
  78. Verma, A. K., Raizada, M. K., Shukla, O. P. and Krishna Murti, C. R. (1974)J. Gen. Microbiol.,80, 307.PubMedGoogle Scholar
  79. Verma, A. K. and Raizada, M. K. (1975)Cell. Differ., 4, 167.PubMedCrossRefGoogle Scholar
  80. Visveswara, G. S. and Balamuth, W. (1975)J. Protozool.,22, 245.Google Scholar
  81. Visweswara, G. S., Jones, D. and Robinson, N. (1975)J. Trop. Med. Hyg.,24, 784.Google Scholar
  82. WHO ({dy1969})Amoebiasis. Tech. Rep. Series No. 421, World Health Organization, Geneva.Google Scholar
  83. Willaret; R, Stevens, A. R. and Tyndall. R. I. (1978)J. Protozool.,25, 1.Google Scholar
  84. Willmer, E. N. (1963)Symp. Soc. Exp. Biol.,17, 215.PubMedGoogle Scholar
  85. Wright, B. E. (1966)Science,153, 830.PubMedCrossRefGoogle Scholar

Copyright information

© Indian Academy of Sciences 1984

Authors and Affiliations

  • C. R. Krishna Murti
    • 1
  • O. P. Shukla
    • 2
  1. 1.Centre for Environmental StudiesCollege of Engineering, Anna UniversityMadrasIndia
  2. 2.Division of BiochemistryCentral Drug Research InstitueLucknowIndia

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