Resumo

LEDEZMA, Yhol et al. Relationship between changes in the expression of proteases and spontaneous metacyclogenesis associated to Trypanosoma cruzi maintenance conditions in the laboratory. Salus [online]. 2013, vol.17, suppl.1, pp.56-67. ISSN 1316-7138.

Trypanosoma cruzi metacyclogenesis is the transformation of epimastigote stage to trypomastigote metacyclic that happens in the rectal ampulla of the insect vector. During this process it has been implicated protein metabolism activation, with proteases likely involvement in parasite protein degradation. In this study we determined the effect of T. cruzi keeping conditions in the laboratory on the activity of proteases and their relationship on spontaneous metacyclogenesis in axenic culture. We worked with Trypanosoma cruzi Dm30L clone maintained in the laboratory by quarterly passes triatomine-mouse (triatomine condition: TC) or serial culture media during 15 years in LITB medium (culture condition: CC). In both conditions, growth curve was made for 30 days in LITB medium supplemented with 10, 24 and 48 mM glucose, calculating the percentage of spontaneous metacyclics and determining proteases activity. In 10 mM glucose, TC parasites showed higher expression of proteases and metacyclic percentage relative to the CC. In TC, the growth in 48 mM glucose reduced the above variables, while no evidenced proteolytic activity nor spontaneous metacyclogenesis on CC parasites in high glucose concentrations. In all cases there was greater cysteine proteases activity during the stationary phase of the culture. Metalloprotease activity was not reported in any of the conditions studied, but it was detected in clone Dm28c used as control of expression of this type of enzyme. These results suggest that the expression of proteases is influenced by the genetic makeup of the parasite and the CC causes decrease of proteolytic activity which persists even in carbohydrate depleted conditions of the medium, with a concomitant significant reduction in the percentage of spontaneous metacyclics.

Palavras-chave : Trypanosoma cruzi; proteases; metacyclogenesis.

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