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Tractable Mammalian Cell Infections with Protozoan-primed Bacteria
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Initial steps of infection of the ciliate Paramecium with bacteria Holospora sp

S I Fokin1, I N Skovorodkin, E V Sabaneyeva

  • 1Biological Research Institute, St. Petersburg State University. fokin@peterlink.ru

Tsitologiia
|March 19, 2004
PubMed

Insights

This study details how intranuclear bacteria (Holospora) infect ciliates (Paramecium) using vesicles and potentially the host cytoskeleton. Some bacteria strains are never taken up by the host cell.

Area of Science:

  • Cell Biology
  • Microbiology
  • Symbiosis Research

Background:

  • Endosymbiosis involves one organism living within another.
  • Intranuclear bacteria (Holospora) infect ciliates like Paramecium.
  • Understanding infection mechanisms is crucial for symbiosis research.

Purpose of the Study:

  • To investigate the initial steps of endosymbiosis establishment between Paramecium and Holospora.
  • To elucidate the role of host cell structures in bacterial transport.
  • To detail the infection process and identify potential barriers.

Main Methods:

  • Light and electron microscopy were used to observe infection dynamics.
  • Analysis of bacterial vesicles and host cell interactions.
  • Microfilament and cytoskeleton association studies.

Main Results:

  • Holospora bacteria are enclosed in host cell phagosome-derived vesicles during cytoplasmic infection.
  • Host cell microfilaments associate with bacterial vesicles, suggesting cytoskeletal involvement in nuclear transport.
  • The infection process was characterized into six distinct steps.
  • Certain Paramecium caudatum strains exhibit resistance to Holospora uptake.

Conclusions:

  • The ciliate cytoskeleton likely plays a role in transporting Holospora bacteria to the nucleus.
  • Vesicle formation from the phagosome membrane is a key step in Holospora infection.
  • Host-pathogen interactions can vary, with some host strains showing resistance.

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