In biology, Kappa organism or Kappa particle refers to inheritable cytoplasmicsymbionts, occurring in some strains of the ciliateParamecium. 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 taeniospiralis.[8]Caedibacter taeniospiralis contains cytoplasmic protein inclusions called R bodies which act as a toxin delivery system.
References
^Sonneborn, T. M. (1950). "Paramecium in modern biology". BIOS. 21 (1): 31–43.
^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. PMID14119554.
^Lawrence E. (1999). Henderson's Dictionary of biological terms. London: Longman Group Ltd. ISBN0-582-22708-9.
^Rieger R. Michaelis A.; Green M. M. (1976). Glossary of genetics and cytogenetics: Classical and molecular. Heidelberg - New York: Springer-Verlag. ISBN0-387-07668-9.
Preer, L. B.; Jurand, A.; Preer Jr, J. R.; Rudman, B. M. (1972). "The classes of kappa in Paramecium aurelia". Journal of Cell Science. 11 (2): 581–600. doi:10.1242/jcs.11.2.581. PMID5076362.
