Resumo

QUERALES, Marvin et al. Metabolic changes during in vitro Trypanosoma cruzi epimastigogenesis. Salus [online]. 2013, vol.17, n.3, pp.6-18. ISSN 1316-7138.

The epimastigogenesis of Trypanosoma cruzi is the transformation from bloodstream trypomastigote to epimastigote that occurs in the anterior portion of the intestinal tract of the insect vector. It has been reported cysteine proteases activation during axenic epimastigogenesis in vitro, suggesting the use of amino acids as a carbon source for the production of energy. The aim of this work was to study through indicators metabolic changes produced during the trypomastigote-epimastigote differentiation. We started with a 100% trypomastigotes derived from Vero cell supernatants, incubated in LITB medium at 27°C under high (horizontal epimastigogenesis) and low (vertical epimastigogenesis) oxygen tension. We estimated parasites number (Neubauer chamber) and differential morphology (Giemsa) at different incubation times (0, 1, 2, 4, 6, 8, 11 and 12 days). Each time was determined in the supernatants of the culture medium glucose and ammonia concentrations as well as the pH values. The results showed that: 1) Regardless of the oxygen tension it was evidenced differentiation forms and amastigote during the process, with the later occurrence of epimastigotes in high oxygen tension; 2) Population growth was significantly greater in high oxygen tension, registering high mortality of amastigotes during the firsts incubation days in the vertical epimastigogenesis; 3) Glucose consumption was concomitant with the appearance of epimastigotes in both conditions, being higher in high oxygen tension; 4) There was no ammonia release in any of the cases studied; 5) The pH values were similar to the sixth day in both conditions, showing gradual acidification of the culture medium at high oxygen tension. Everything seems to suggest that during the epimastigogenesis of T. cruzi parasites involved in differentiation processes show no activation of different metabolic pathways.

Palavras-chave : Trypanosoma cruzi; metabolism; epimastigogenesis.

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