Resumen de The Stressful Life of Pathogenic Leishmania Species
Leishmania parasites are unicellular protozoa descending from one of the oldest eukaryotic lineages. During its digenetic life cycle, Leishmania alternates between the alimentary tract of the sandfly vector as an extracellular promastigote and the acidic phagolysosomes of macrophage cells as an intracellular amastigote. Parasites must cope with varied and heterogeneous environments: changes in temperature, in pH, in nutrient and oxygen concentrations. Also, they must face the immune defences, such as complement factors, free radicals and other antimicrobial effectors. The focus of this chapter will be on our current knowledge of the different stress responses in Leishmania, ranging from description of the prototypical heat shock response to more specific responses found in this parasite. A comprehensive view on the implications of the stress response in parasite survival, in cytodifferentiation and in apoptotic processes will be presented. Future studies, which should be directed mainly to the uncovering of the stress sensors, signal transduction pathways and regulatory mechanisms leading to the induction of the appropriate stress response will be also discussed.
