Experimental Studies on Entamoeba with Reference to Speciation

Abstract

Publisher Summary The chapter focuses on the experimental studies on Entamoeba with reference to speciation. Species of Entamoeba can be divided into three groups based on the number of nuclei in the mature cyst, the number being eight, four, or one. The best known species of the 8- and 4-nucleate cyst groups are the human parasites E. coli and E. histolytica respectively. The species illustrated in the chapter are 8-nucleate cyst group, E. coli from man and E. gallinarum from fowl; 4-nucleate cyst group, E, histolytica and E. hartmanni from man; 1-nucleate cyst group, E. chattoni from monkey, E. bovis from cow and E. debliecki from goat. The morphological studies discussed have concentrated on three aspects: (1) the relationship of the large and small races of E. histolytica (known as E. histolytica and E. hartmanni respectively); (2) the occurrence in man of a different species of Entamoeba, which forms 1-nucleate cysts, E. polecki; and (3) the electron microscopy of amoebae and cysts. Electron microscopy has revealed some differences of subcellular organization between Entamoeba and metazoan cells. A great deal of research effort has been devoted to studying the immunology of the human species, E. histolytica. Various immunological methods have been adapted for use with Entamoeba antigens, for example precipitins, indirect haemagglutination, complement fixation, inhibition of red blood cell phagocytosis by specific antisera, inhibition of amoebic growth, and fluorescent antibody. These are described in the chapter. The results of DNA distribution are also discussed.