title: Effect of methylene blue and illumination on the process of differentiation of the protozoan Herpetomonas samuelpessoai.
abstract: Herpetomonas samuelpessoai is a non-pathogenic protozoan that shares important antigens with Trypanosoma cruzi (the agent of Chagas' disease) and which shows three developmental stages: promastigote, paramastigote and the highly differentiated form opisthomastigote. Due to the difficulties in obtaining the last form, its physiology and biochemistry are not well understood, and procedures which can induce the process of differentiation promastigote-opisthomastigote are desirable. In this work we show that illumination of H. samuelpessoai with white light in the presence of methylene blue and oxygen (photodynamic effect) triggers the process of differentiation in a very efficient manner (the cultures show up to 70 per cent of the cells in the opisthomastigote form). We also observed that illumination alone and incubation with methylene blue in the dark can trigger the process but in levels markedly lower than illumination in the presence of the dye.
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000528:radiation effects; D008027:Light; D008751:Methylene Blue / Q000494:pharmacology*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D014345:Trypanosoma / Q000166:cytology* / Q000187:drug effects / Q000528:radiation effects
chemical_list: D011838:Radiation-Sensitizing Agents; D008751:Methylene Blue