Effect of Japanese Paramecium bursaria extract on photosynthetic carbon fixation of symbiotic algae

  • Kamako S
  • Imamura N
  • 19


    Mendeley users who have this article in their library.
  • 14


    Citations of this article.


To investigate the relationship between the Japanese Paramecium bursaria host and its symbiont, we studied the effect of a host cell-free extract on carbon fixation and photosynthate release of the symbiont. The host extract enhanced symbiotic algal carbon fixation about 3-fold at an increased concentration; however, release of photosynthate hardly changed. Since the enhancing effect was not affected by elimination of carbon dioxide from the host extract, the existence of a host factor that stimulates algal carbon fixation was made clear. The host factor is a heat-stable, low molecular weight substance. In relation to the pH dependence, the extract improved carbon fixation at acidic and neutral pH and showed almost no effect at pH 9.0. Therefore, the stimulation of carbon fixation by the host factor is unlikely to be caused by intracellular pH change. The extract also improved carbon fixation of several Chlorella species, symbiotic and free-living, and apparently exhibited no species specificity. Therefore, the host seems to regulate the photosynthesis of the symbiont via a specific compound.

Author-supplied keywords

  • Endosymbiont
  • Host factor
  • Paramecium bursaria
  • Photosynthesis
  • pH

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


  • Shin Ichiro Kamako

  • Nobutaka Imamura

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free