Enzyme variation among clones of Trypanosoma cruzi

The genetic relationships within and between stocks of Trypanosoma cruzi were studied by the in vitro isolation of clones and sub-clones and by the comparison of their isoenzyme patterns in thin-layer starch-gel electrophoresis. Altogether 13 clones and 36 sub-clones were isolated from stocks CL89 and Y207 of T. cruzi. Employing the enzymes L-alanine aminotransferase (ALAT), L-aspartate aminotransferase (ASAT), glucose phosphate isomerase (GPI), malic enzyme (ME), malate dehydrogenase (MDH), glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), and phosphoglucomutase (PGM), two zymodemes, B and C, emerged among the clones with distinct banding patterns. These zymodemes were consistently distinguished by ALAT, ASAT, GPI, G6PD, 6PGD, and PGM and the differences in enzyme profiles were simultaneously reflected in all six enzyme systems. That the enzymic characters as genetic determinants are stable was demonstrated after recloning and successive replica-platings, i.e., the distinct enzyme patterns remained consistent and homogeneous, the siblings retained the enzyme profiles of their parental clones, and no segregation of the enzyme patterns was observed. Our data from clone and sub-clone examinations show that the isoenzymes act as labels to characterize T. cruzi stocks. Furthermore, enzyme variation was demonstrated among clones isolated from stock CL89.