Document Detail

Microscopic analysis of calcium ionophore activated egress of Toxoplasma gondii from the host cell.
MedLine Citation:
PMID:  19875235     Owner:  NLM     Status:  MEDLINE    
Toxoplasma gondii invades and destroys nucleated cells of warm blooded hosts in a process which involves several steps: recognition, adhesion, penetration, multiplication inside a parasitophorous vacuole (PV) and egress. The last one is the least understood. Parasite egress from LLC-MK2 cells infected with the RH strain of T. gondii was artificially triggered with 4BrA23187 calcium ionophore. The combination of videomicroscopy, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) showed that egress does not result from host cell rupture due to overloading with tachyzoites. Videomicroscopy showed that upon calcium ionophore administration parasite rosettes disassemble, the contour of the parasitophorous vacuole disappears and each tachyzoite takes a separate route to the extracellular medium. FESEM and TEM showed the fragmentation of the intravacuolar network, the fragmentation of parasitophorous vacuole membrane and individual tachyzoites with extruded conoids migrating through the cytosol, tightly surrounded by remnants of parasitophorous vacuole membrane or free in the cytosol. Both videomicroscopy and FESEM showed that a single parasite can cross the host cell membrane without disrupting it, while a large number of parasites, egressing simultaneously, rupture the membrane and the cell as a whole. These data suggest that invasion and egress share less similarities than previously believed.
Lucio Ayres Caldas; Wanderley de Souza; M?rcia Attias
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-10-04
Journal Detail:
Title:  Veterinary parasitology     Volume:  167     ISSN:  1873-2550     ISO Abbreviation:  Vet. Parasitol.     Publication Date:  2010 Jan 
Date Detail:
Created Date:  2010-02-01     Completed Date:  2010-04-29     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7602745     Medline TA:  Vet Parasitol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  8-18     Citation Subset:  IM    
Copyright Information:
Copyright 2009 Elsevier B.V. All rights reserved.
Laborat?rio de Ultraestrutura Celular Hertha Meyer, Instituto de Biof?sica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil.
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MeSH Terms
Calcimycin / pharmacology
Calcium / physiology*
Cell Line
Cell Membrane / parasitology*,  physiology,  ultrastructure
Ionophores / pharmacology
Macaca mulatta
Microscopy, Electron, Scanning
Microscopy, Electron, Transmission
Microscopy, Video
Toxoplasma / physiology*,  ultrastructure
Toxoplasmosis / parasitology*
Vacuoles / parasitology*,  physiology,  ultrastructure
Reg. No./Substance:
0/Ionophores; 52665-69-7/Calcimycin; 7440-70-2/Calcium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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