Entamoeba histolytica zymodemes: exhibition of gamma and delta bands only of glucose phosphate isomerase and phosphoglucomutase may be influenced by starch content in the medium

Entamoeba histolytica isolated from human can be associated with either symptomatic disease or with asymptomatic carriers. Pathogenic and nonpathogenic strains can be distinguished on the basis of differences in the electrophoretic patterns of four isoenzymes (zymodeme). With glucose phosphate isomerase and phosphoglucomutase, we observed variation of the expression of their gamma bands as a function of starch volume in culture. We cultured E. histolytica strains from different zymodemes in Robinson medium using both a low (2-4 mg/bottle) and a high (12-15 mg/bottle) content of rice starch as supplement. These cultures were monitored by electrophoresis of glucose phosphate isomerase and phosphoglucomutase. Strains having gamma or delta bands exhibited those bands when a high content of starch was used in culture, but did not do so with a low content. Contrarily, strains that never exhibited those bands did not express them when the amount of starch in the culture was increased. However, alpha and beta bands of the same isoenzymes were always present and never showed any variation. The results suggest that expression of gamma and delta bands of glucose phosphate isomerase and phosphoglucomutase are subject to culture conditions and that genes coding for those isoenzymes may be different from those coding for the alpha and beta bands

Experimental production of new zymodemes of Entamoeba histolytica supports the hypothesis of genetic exchange

By mixing in culture zymodemes of Entamoeba histolytica, clones showing a different pattern from the 2 parents have been obtained on 3 occasions. Two new zymodemes (XI alpha- and XXI) have thus been produced, which belong to the third generation of a family of E. histolytica zymodemes apparently obtained by genetic exchange. A hypothesis for the molecular basis of those exchanges is discussed. We report also the observation of probable mutation