title: Morphological changes during conoid extrusion in Toxoplasma gondii tachyzoites treated with calcium ionophore.
abstract: Treatment of tachyzoites of Toxoplasma gondii with the calcium ionophore A23187 induced dramatic ultrastructural changes that were observed by light and electron microscopy. Light microscopy showed a higher percentage (22%) of tachyzoites with the conoid extruded when compared to control parasites. Electron microscopy confirmed the conoid extrusion by both transmission and scanning electron microscopy. Freeze-fracture replicas showed that the plasma membrane adjacent to cytoplasmic dense granules appeared devoid of intramembranous particles. Membrane-limited vesicles and filopodium-like structures at the cell surface were observed in treated cells. 3-D reconstruction from serial sections confirmed the data and showed a heterogeneity in dense granule shape not reported in control cells.
authors.affiliation: Laboratório de Biologia Celular e Tecidual, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Avenida Alberto Lamego 2000, Campos, RJ, Brazil.
authors.forename: V G
authors.initials: VG
authors.lastname: Monteiro
authors.forename: E J
authors.initials: EJ
authors.lastname: de Melo
authors.forename: M
authors.initials: M
authors.lastname: Attias
authors.forename: W
authors.initials: W
authors.lastname: de Souza
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology*; D002462:Cell Membrane / Q000648:ultrastructure; D005614:Freeze Fracturing; D007091:Image Processing, Computer-Assisted; D007425:Intracellular Membranes / Q000648:ultrastructure; D007476:Ionophores / Q000494:pharmacology; D008854:Microscopy, Electron; D014122:Toxoplasma / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure*
chemical_list: D007476:Ionophores; D000001:Calcimycin