Formation of polyribosomal crystals in Entamoeba histolytica by hyperosmotic solution of NaCl

Abstract

Entamoeba histolytica is a parasitic protozoan that during its life cycle presents two different biological forms; the trophozoite that is a pleomorphic, motile and phagocytic organism, and the cyst that is small, nonmotile and rounded form covered by an external fibrous coat. Differentiation of trophozoites into the cyst involves a series of complex events including the organization of helical polyribosomes within a crystal known as the chromatoid body. Induction of this differentiation has been achieved experimentally in hypoosmotic medium composed of Mg SO4 and bovine serum (100 mOs/kg) in Entamoeba invadens, a reptilian parasite. However, Entamoeba histolytica is unable to survive when treated on the above conditions. Due to the biological importance of understanding which are the physiological conditions that may elicit ency station of this organism, we cultured trophozoites in TYI-S-33 medium containing NaCl to a final osmolality of 400, 500, 600 and 800 mOs/kg. Parasites were observed directly through a videosystem and noticed that at 600 mOs the trophozoites stop moving and rounded in about 3 min, similar results were obtained at 800 mOs.