CYTOMETRY AND KARYOMETRY IN TRYPANOSOMA-CRUZI

A total of 991 Trypanosoma cruzi cells, from four laboratory stocks, i ncluding the three differentiation forms, had their cellular outlines, nuclei and kinetoplasts measured at 9000 x magnification. Data on the identifiable cell cycle stages were used to search for intraspecific and biological cycle heterogeneity. Cellular areas (CA) in the interph asic differentiation forms produced ratios of 1.07 for culture epimast igotes (E), 1 for blood trypomastigotes (T), and 0.86 for tissue forms (A). Homogeneity in terms of nuclear (NA) and kinetoplast (KA) areas prevailed among the stocks, with differences of at most 6%, for modal NA of strains CL and Y. NA of T-form was larger than the basic NA of e arly G1 A-form. T-form kinetoplast volume was 3-fold that of A-form K- DNA nucleoids.One of the two recently divided kinetoplasts in mitotic E-form did not correlate with CA, indicating that mitochondrial divisi on was unequal. The KA of CL strain T-form did not correlate with NA, suggesting a mitochondrial disfunction in this thermosensitive strain. The CL strain T-form was more heterogeneous than the Y strain for all characters, showing greater frequency of large values, even reaching the G2 levels. This heterogeneity was interpreted as functional, conse quent to the thermosensitivity of the CL strain. Precocious bursting o f CL strain host cells would lead to the polymorphic T-forms. Post-S p hase trypomastigotes could start division soon after penetration of ho st cells.