Related Experiment Video

Updated: Jun 26, 2026

Measurements of Physiological Stress Responses in C. Elegans
10:36

Measurements of Physiological Stress Responses in C. Elegans

Published on: May 21, 2020

Micronucleus-specific bacterium Holospora elegans irreversibly enhances stress gene expression of the host Paramecium

Manabu Hori1, Kimiko Fujii, Masahiro Fujishima

  • 1Division of Environmental Science and Engineering, Graduate School of Environmental Science and Engineering, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8512, Japan. mhori@yamaguchi-u.ac.jp

The Journal of Eukaryotic Microbiology
|January 6, 2009
PubMed

Insights

Paramecium ciliates infected with Holospora bacteria gain heat-shock resistance. Even after bacteria removal, aposymbiotic ciliates retain this resistance, suggesting transferred bacterial DNA may trigger a stress response.

Area of Science:

  • Microbiology
  • Cell Biology
  • Symbiosis

Background:

  • Holospora bacteria are endonuclear symbionts of Paramecium ciliates.
  • Previous studies showed Holospora obtusa enhances host survival and heat-shock resistance.
  • Paramecia with symbionts exhibit high hsp70 mRNA levels even at normal growth temperatures.

Purpose of the Study:

  • To investigate if the micronuclear-specific symbiont Holospora elegans confers heat-shock resistance to Paramecium.
  • To explore the mechanisms behind this acquired heat-shock resistance, particularly in aposymbiotic (symbiont-free) cells.

Main Methods:

  • Heat-shock resistance assays on symbiotic and aposymbiotic Paramecium.
  • Quantitative analysis of hsp60 and hsp70 mRNA expression using quantitative PCR.
  • Fluorescent in situ hybridization (FISH) using a probe specific for Holospora 16S rRNA.

Main Results:

  • Paramecia harboring Holospora elegans acquired significant heat-shock resistance.
  • Aposymbiotic paramecia, even after 1 year of symbiont removal, maintained heat-shock resistance.
  • Both symbiotic and aposymbiotic paramecia showed elevated hsp60 and hsp70 mRNA levels at 25°C.
  • FISH analysis revealed Holospora 16S rRNA in the macronucleus of aposymbiotic cells.

Conclusions:

  • Holospora elegans symbiosis confers sustained heat-shock resistance to Paramecium.
  • The maintenance of heat-shock resistance in aposymbiotic cells suggests a persistent effect of the symbiosis.
  • Evidence suggests potential horizontal gene transfer of Holospora DNA to the host macronucleus, triggering stress responses and heat-shock protein production.

More Related Videos

Investigating the Spreading and Toxicity of Prion-like Proteins Using the Metazoan Model Organism C. elegans12:57

Investigating the Spreading and Toxicity of Prion-like Proteins Using the Metazoan Model Organism C. elegans

Published on: January 8, 2015

Studying Oxidative Stress Caused by the Mitis Group Streptococci in Caenorhabditis elegans09:36

Studying Oxidative Stress Caused by the Mitis Group Streptococci in Caenorhabditis elegans

Published on: March 23, 2019

Related Concept Videos

Other Stress Responses in Bacteria01:30

Other Stress Responses in Bacteria

Bacteria have global regulatory systems that control several types of stress mechanisms. These include Pho regulon and the heat shock response, which are essential systems for environmental adaptation, such as nutrient limitation and proteotoxic stress. The Pho regulon and the heat shock response exemplify bacterial resilience, enabling rapid adaptation to fluctuating environmental conditions.Pho RegulonBacteria require phosphorus for essential cellular processes, including nucleic acid...
Stringent Response in E. coli01:23

Stringent Response in E. coli

Bacterial growth is closely tied to nutrient availability, with cells proliferating exponentially under favorable conditions and entering a stationary phase when resources become scarce. This transition is mediated by a regulatory mechanism known as the stringent response, which allows bacteria to adapt to nutrient deprivation by modulating gene expression and metabolic activity.During nutrient scarcity, intracellular amino acid levels decline. It results in the accumulation of uncharged tRNAs...
Gene Regulation During Sporulation01:17

Gene Regulation During Sporulation

Sporulation is a complex developmental process that allows certain Gram-positive bacteria, such as Bacillus subtilis and Clostridium species, to survive extreme environmental conditions. This process is tightly regulated by a series of signaling cascades and transcriptional controls, ensuring the formation of a highly resistant endospore.Sporulation is triggered by unfavorable conditions, such as nutrient depletion, and is governed by a phosphorelay system. One of the sensor kinases, such as...