title: Differentiation of Leishmania donovani in host-free system: analysis of signal perception and response.
abstract: Leishmania donovani are the causative agents of kala-azar in humans. They undergo a developmental program following changes in the environment, resulting in the reversible transformation between the extracellular promastigote form in the sand fly vector and the obligatory intracellular amastigote form in phagolysosomes of macrophages. A host-free differentiation system for L. donovani was used to investigate the initial process of promastigote to amastigote differentiation. Within an hour after exposing promastigotes to differentiation signal (concomitant exposure to 37 degrees C and pH 5.5), they expressed the amastigote-specific A2 protein family. At 5 h they started to transform to amastigote-shaped cells, a process that was completed 7 h later. This morphological transformation occurred synchronously, while cells arrested at G1. By sequential exposure to elevated temperature (for 24 h) and then acidic pH, we found that heat was responsible for the growth arrest and acidic pH to its release and subsequent route to differentiation into amastigotes. Lastly, ethanol and Azetidine 2 carboxylic acid (a synthetic proline analog) that induced heat shock response in promastigotes were capable of replacing heat in the differentiation signal.
authors.affiliation: Department of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel.
authors.forename: Efrat
authors.initials: E
authors.lastname: Barak
authors.forename: Sigal
authors.initials: S
authors.lastname: Amin-Spector
authors.forename: Elena
authors.initials: E
authors.lastname: Gerliak
authors.forename: Sophie
authors.initials: S
authors.lastname: Goyard
authors.forename: Neta
authors.initials: N
authors.lastname: Holland
authors.forename: Dan
authors.initials: D
authors.lastname: Zilberstein
mesh_terms: D000818:Animals; D000953:Antigens, Protozoan / Q000378:metabolism; D001383:Azetidinecarboxylic Acid; D002453:Cell Cycle; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D000431:Ethanol; D016193:G1 Phase; D006863:Hydrogen-Ion Concentration; D007893:Leishmania donovani / Q000166:cytology* / Q000378:metabolism; D015800:Protozoan Proteins / Q000378:metabolism; D013696:Temperature; D013997:Time Factors
chemical_list: C107645:A2 protein, Leishmania donovani; D000953:Antigens, Protozoan; D015800:Protozoan Proteins; D000431:Ethanol; D001383:Azetidinecarboxylic Acid