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Dynamics and 3D organization of secretory organelles of Toxoplasma gondii.
MedLine Citation:
PMID:  22155668     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Micronemes, rhoptries and dense granules are secretory organelles of Toxoplasma gondii crucial for host cell invasion and formation of the parasitophorous vacuole (PV). We examined whether their relative volumes change during the intracellular cycle. Stereological analysis of random ultrathin sections taken at 5min of interaction, 7 and 24h post-infection demonstrated that the relative volume of each type of organelle decreases just after the respective peak of secretion. Micronemes are radially arranged below the polar ring, while rhoptries converge to but only a few reach the inside of the conoid. In contrast to the apical and polarized organelles, dense granules were found scattered throughout the cytoplasm, with no preferential location in the parasite cell body. Extensive observation of random sections indicated that each organelle probably secretes in a different region. Micronemes secrete just below the posterior ring and probably require that the conoid is extruded. The rhoptries passing through the conoid secrete at a porosome-like point at the most apical region. Dense granules secrete laterally, probably at fenestrations in the inner membrane complex. Immunocytochemistry showed that there are no subpopulations of rhoptries or dense granules, as a single organelle can contain more than one kind of its specific proteins. The vacuolar-like profiles observed at the apical portion of parasites just after invasion were confirmed to be empty rhoptries, as they were positively labeled for rhoptry proteins. These findings contribute for a better understanding of the essential behavior of secretory organelles.
Authors:
Tatiana Christina Paredes-Santos; Wanderley de Souza; Márcia Attias
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-12-4
Journal Detail:
Title:  Journal of structural biology     Volume:  -     ISSN:  1095-8657     ISO Abbreviation:  -     Publication Date:  2011 Dec 
Date Detail:
Created Date:  2011-12-13     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9011206     Medline TA:  J Struct Biol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011. Published by Elsevier Inc.
Affiliation:
Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem, Brazil.
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