Kappa organism

From Wikipedia, the free encyclopedia
  (Redirected from Paramecin)
Jump to navigation Jump to search

In biology, Kappa organism or Kappa particle refers to inheritable cytoplasmic symbionts, occurring in some strains of the ciliate Paramecium. Paramecium strains possessing the particles are known as "killer paramecia". They liberate a substance also known as paramecin[1][2] into the culture medium that is lethal to Paramecium that do not contain kappa particles. Kappa particles are found in genotypes of Paramecium aurelia syngen 2 that carry the dominant gene K.[3][4]

Kappa particles are Feulgen-positive and stain with Giemsa after acid hydrolysis. The length of the particles is 0.2–0.5μ.[5]

While there was initial confusion over the status of kappa particles as viruses, bacteria, organelles,[6] or mere nucleoprotein,[7] the particles are intracellular bacterial symbionts called Caedibacter taenospiralis.[8] Caedibacter taenospiralis contains cytoplasmic protein inclusions called R bodies which act as a toxin delivery system.


  1. ^ Sonneborn, T. M. (1950). "Paramecium in modern biology". Bios. 21 (1): 31–43. 
  2. ^ Takayanagi, Tan; Hayashi, Shinji (1964). "Cytological and Cytogenetical Studies on Paramecium polycaryum. V. Lethal Interactions in Certain Stocks". Journal of Eukaryotic Microbiology. 11 (1): 128–132. doi:10.1111/j.1550-7408.1964.tb01733.x. 
  3. ^ Lawrence E. (1999). Henderson's Dictionary of biological terms. London: Longman Group Ltd. ISBN 0-582-22708-9. 
  4. ^ Rieger R. Michaelis A., Green M. M. (1976). Glossary of genetics and cytogenetics: Classical and molecular. Heidelberg - New York: Springer-Verlag. ISBN 0-387-07668-9. 
  5. ^ Brown, C. H. (1950). "Elimination of Kappa Particles from 'Killer' Strains of Paramecium aurelia by Treatment with Chloromycetin". Nature. 166 (4221): 527. doi:10.1038/166527A0. 
  6. ^ Kappa Particles in mediLexicon
  7. ^ Kappa Particles in McGraw-Hill Science & Technology Dictionary
  8. ^ Pond, F. R.; Gibson, I.; Lalucat, J.; Quackenbush, R. L. (1989-03-01). "R-body-producing bacteria". Microbiological Reviews. 53 (1): 25–67. ISSN 0146-0749. PMC 372716Freely accessible. PMID 2651865. 

External links[edit]

See also[edit]