Abstract:

The presence of a nitric oxide (NO) pathway in Trypanosoma cruzi epimastigotes was demonstrated. The following components of that pathway were found: glutamate/NMDA receptors, a soluble Ca2+ calmodulin-dependent NO synthase and a soluble Na nitroprussideactivated guanylyl cyclase. In epimastigotes, glutamate or NMDA stimulated the conversion of L-arginine to citrulline and increased cell motility. These stimulations could be blocked by MK-801 and ketamine and enhanced by glycine or serine. Motility was also stimulated by L-arginine and Na nitroprusside. In T. cruzi epimastigotes, a specific, Na+-independent, L-arginine transport system was also found. After L-arginine uptake, P-arginine was generated; a L-arginine kinase activity was characterized. Using murine cDNA probes of c-fos and c-jun at low stringency, hybridization signals were detected in restriction fragments of T. cruzi DNA. Employing polyclonal sera raised against human c-fos and c-jun, specific polypeptide bands of about 36 and 40-50 kDa, respectively, were observed in Western blots of cytosolic or nuclear extracts. Moreover, in electrophoretic mobility shift assays using a TRE probe, three specific complexes were obtained which were increased by oxidative stress induced by hydrogen peroxide, and by the entrance of the culture into the stationary phase. (Supported by CONICET, UBA, F. Antorchas and ICGEB).