EXTRACELLULAR PHOSPHORYLATION IN LEISHMANIA-MAJOR AND LEISHMANIA-MEXICANA DURING HEAT-SHOCK TRANSFORMATION

The extracellular phosphorylation of exogenous substrates have been st udied in two Leishmania isolates, L. mexicana and L. major, that diffe r in their capacity to transform from promastigotes to amastigote-like cells when submitted to heat shock condition. When submitted to heat shock both parasites showed an increase in their extracellular phospho rylation activity. L. major promastigotes that do not transform to ama stigote-like cells at 37 degrees C, do not phosphorylate exogenous sub strate when the culture is grown at 25 degrees C. In contrast, L. mexi cana promastigotes, that transform to amastigote-like cells at 37 degr ees C, showed a strong phosphorylation at this temperature. As respons e to heat shock exposure, the extracellular phosphorylation for L. maj or increases steadily reaching a maximum at 360 min. On the other hand , L. mexicana also show an increase in phosphorylation during transfor mation, but in this case the maximum was detected after 10 min. The re sults are discussed in relationship to the capacity of the parasite to survive once inside the vertebrate host.