The enigma of eugregarine epicytic folds: where gliding motility originatesReportar como inadecuado

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Frontiers in Zoology

, 10:57

First Online: 22 September 2013Received: 19 January 2013Accepted: 24 August 2013


BackgroundIn the past decades, many studies focused on the cell motility of apicomplexan invasive stages as they represent a potential target for chemotherapeutic intervention. Gregarines Conoidasida, Gregarinasina are a heterogeneous group that parasitize invertebrates and urochordates, and are thought to be an early branching lineage of Apicomplexa. As characteristic of apicomplexan zoites, gregarines are covered by a complicated pellicle, consisting of the plasma membrane and the closely apposed inner membrane complex, which is associated with a number of cytoskeletal elements. The cell cortex of eugregarines, the epicyte, is more complicated than that of other apicomplexans, as it forms various superficial structures.

ResultsThe epicyte of the eugregarines, Gregarina cuneata, G. polymorpha and G. steini, analysed in the present study is organised in longitudinal folds covering the entire cell. In mature trophozoites and gamonts, each epicytic fold exhibits similar ectoplasmic structures and is built up from the plasma membrane, inner membrane complex, 12-nm filaments, rippled dense structures and basal lamina. In addition, rib-like myonemes and an ectoplasmic network are frequently observed. Under experimental conditions, eugregarines showed varied speeds and paths of simple linear gliding. In all three species, actin and myosin were associated with the pellicle, and this actomyosin complex appeared to be restricted to the lateral parts of the epicytic folds. Treatment of living gamonts with jasplakinolide and cytochalasin D confirmed that actin actively participates in gregarine gliding. Contributions to gliding of specific subcellular components are discussed.

ConclusionsCell motility in gregarines and other apicomplexans share features in common, i.e. a three-layered pellicle, an actomyosin complex, and the polymerisation of actin during gliding. Although the general architecture and supramolecular organisation of the pellicle is not correlated with gliding rates of eugregarines, an increase in cytoplasmic mucus concentration is correlated. Furthermore, our data suggest that gregarines utilize several mechanisms of cell motility and that this is influenced by environmental conditions.

KeywordsActin Cytochalasin D Epicyte Epicytic folds Eugregarine Glideosome Gliding motility Jasplakinolide Mucus Myosin Pellicle AbbreviationsActActin

CLSMConfocal laser scanning microscopy

DMSODimethyl sulfoxide

EFExoplasmic fracture

F-actFilamentous actin

FITCFluorescein isothiocyanate

IFAIndirect immunofluorescent assay

IMCInner membrane complex

IMPIntramembranous particles


KpPartition coefficient

LMLight microscopy


PFProtoplasmic fracture

PBSPhosphate buffered saline

SEStandard error

SEMScanning electron microscopy

TEMTransmission electron microscopy

TRITCTetramethylrhodamine B isothiocyanate.

Electronic supplementary materialThe online version of this article doi:10.1186-1742-9994-10-57 contains supplementary material, which is available to authorized users.

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Autor: Andrea Valigurová - Naděžda Vaškovicová - Naďa Musilová - Joseph Schrével


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