Authors
F S Damasceno1; S Marsiccobetre1; R O Souza1; A M Silber1; 1 Biomedical Science Institute - USP, Brazil Discussion
Trypanosoma cruzi is the causative agent of American trypanosomiasis, also known as Chagas disease. T. cruzi life cycle alternates between the mammalian hosts, among them the humans and the insect vector, a reduviid insect. Inside the both host T. cruzi differentiate into five mainly stages: amastigote, intracellular epimastigote and trypomastigote in the mammalian host and epimastigotes and metacyclic trypomastigote in the insect vector. Thus, T. cruzi needs to colonize different environments, such as, the bloodstream and cells cytoplasm in the mammalian host, and the intestine in the insect vector. These environments offer different nutrient compositions, including the availability of carbon sources. In our work we demonstrate the important role of Glutamine (Gln) in the parasite survival in the different environments during their life cycle. T. cruzi can obtain Gln by the uptake from the external medium or can synthesize it using glutamate, ATP and NH4+ as substrates, both systems act as complementary source of Gln through the life stages of the parasite. Moreover, out data shown that Gln is a relevant metabolite to many biological processes in the parasite: the proliferetation of epimastigotes forms, differentiation from epimastigotes to metacyclic trypomastigote, a process call metacyclogenesis, and participates in the intracellular cycle in the mammalian host. Also Gln participates as energy source; Gln is completely oxidized to CO2 and can feed the electron transport chain, contributing to ATP biosynthesis. Taken together, these data showed that Gln is an example of adaptation of T. cruzi according to nutrient availability. 
