A new aspect of the morphological transformation of Trypanosoma cruzi brought about by environmental variation
Ribeiro, R.D.; Lopes, R.A.; Garcia, T.A.; Carraro, A.A.
Angewandte Parasitologie 31(4): 207-210
1990
ISSN/ISBN: 0003-3162 PMID: 2085209 Document Number: 347781
Aspects of the transformation of T. cruzi inside triatomines, in culture media and in saline solution were studied. Examination of bloodstream forms of T. cruzi, Y and Bolivian strains, after 24 h of incubation in culture medium and in saline at 4 degrees C and 30 degrees C initially revealed trypanosome pairing and joining, with intense nucleus and kinetoplast motion and kinetoplast joining. Flagellate separation and/or passage of nuclear and kinetoplast content from one individual to the other was observed later in both strains. After 48 h of incubation, rounded forms appeared and approached the pairs or clustered into a greater or smaller number of elements. Fused rounded forms also appeared. The formation of spherical elements resembling previously described cyst-like bodies was also observed. When examined fresh, these elements appeared to be static and showed inner structures moving around in circles or in a disorderly manner. The rounded forms occurred more frequently in the Bolivia strain and the cyst-like bodies occurred at similar frequencies in both strains. The triatomines (5th instar Triatoma infestans and Panstrongylus megistus) allowed to feed on the infected mice were dissected 24 h after the blood meal and their stomach contents were examined via both fresh and in Giemsa-stained smears. The ingested bloodstream trypomastigotes showed a behaviour similar to that observed in the in vitro experiments. However, rounded forms appeared earlier and with more intensity in the Bolivia strain and in T. infestans. On the basis of the molecular studies carried out by other authors, who observed that not all proteins synthetized from DNA are of immediate usefulness in the cell, but need to undergo activation by the action of another protein or of environmental variation, it may be inferred that T. cruzi, under adverse conditions, i.e. a change in habitat, may undergo transformations, taking on different forms for the exchange of genetic information for adaptation to the environment and for possible continuity of the evolutionary cycle.