GENETIC EXCHANGE AS A POSSIBLE SOURCE OF GENOMIC DIVERSITY IN SYLVATIC POPULATIONS OF TRYPANOSOMA-CRUZI

Thirty six stocks of Trypanosoma cruzi isolated from sylvatic mammals (32 Didelphis marsupialis and one Philander opossum) and triatomine bu gs (Rhodnius robustus and one unidentified bug) in the Amazonian fores t of Carajas, Brazil were characterized by isoenzyme and random amplif ied polymorphic DNA (RAPD) analysis as belonging to principal zymodeme 1 (Z1). Two different homozygous phenotypes and the corresponding het erozygous phenotype were found for phosphoglucomutase with an observed frequency almost identical with that predicted by the theoretical Har dy-Weinberg distribution. Parental and hybrid profiles were also sugge sted by RAPD analysis, which allowed exclusion of mixed parental strai ns from the hybrids: isoenzyme and RAPD profiles of biological clones were also indistinguishable from those of uncloned stocks. Trypanosoma cruzi stocks from widely separated geographic origins in Central and South America gave similar RAPD profiles that allowed them to be recog nized as being Z1. These results indicate that genetic exchange could contribute to the generation of genetic diversity during the sylvatic cycle of T. cruzi, and this may have epidemiologic and taxonomic impli cations.