Burrell, Alana;
Marugan-Hernandez, Virginia;
Graefin Von Der Recke, Karolin;
Aguiar-Martins, Kelsilandia;
Gabriel, Heloisa Berti;
Tomley, Fiona M.;
Vaughan, Sue
Refractile bodies of Eimeria tenella are proteinaceous membrane-less organelles that undergo dynamic changes during infection
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Media type:
E-Article
Title:
Refractile bodies of Eimeria tenella are proteinaceous membrane-less organelles that undergo dynamic changes during infection
Contributor:
Burrell, Alana;
Marugan-Hernandez, Virginia;
Graefin Von Der Recke, Karolin;
Aguiar-Martins, Kelsilandia;
Gabriel, Heloisa Berti;
Tomley, Fiona M.;
Vaughan, Sue
imprint:
Frontiers Media SA, 2023
Published in:Frontiers in Cellular and Infection Microbiology
Description:
<jats:sec><jats:title>Introduction</jats:title><jats:p>Refractile bodies (RB) are large membrane-less organelles (MLO) of unknown function found as a prominent mismatched pair within the sporozoite stages of all species of <jats:italic>Eimeria</jats:italic>, parasitic coccidian protozoa.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>High resolution imaging methods including time-lapse live confocal microscopy and serial block face-scanning electron microscopy (SBF-SEM) were used to investigate the morphology of RB and other intracellular organelles before and after sporozoite invasion of host cells.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Live cell imaging of MDBK cells infected with <jats:italic>E. tenella</jats:italic> sporozoites confirmed previous reports that RB reduce from two to one post-infection and showed that reduction in RB number occurs <jats:italic>via</jats:italic> merger of the anterior RB with the posterior RB, a process that lasts 20-40 seconds and takes place between 2- and 5-hours post-infection. Ultrastructural studies using SBF-SEM on whole individual sporozoites, both pre- and post-host cell invasion, confirmed the live cell imaging observations and showed also that changes to the overall sporozoite cell shape accompanied RB merger. Furthermore, the single RB post-merger was found to be larger in volume than the two RB pre-merger. Actin inhibitors were used to investigate a potential role for actin in RB merger, Cytochalasin D significantly inhibited both RB merger and the accompanying changes in sporozoite cell shape.</jats:p></jats:sec><jats:sec><jats:title>Discussion</jats:title><jats:p>MLOs in eukaryotic organisms are characterised by their lack of a membrane and ability to undergo liquid-liquid phase separation (LLPS) and fusion, usually in an actin-mediated fashion. Based on the changes in sporozoite cell shape observed at the time of RB merger together with a potential role for actin in this process, we propose that RB are classed as an MLO and recognised as one of the largest MLOs so far characterised.</jats:p></jats:sec>