Towards an ecological understanding of the killer trait - A reproducible protocol for testing its impact on freshwater ciliates.

Autor: Koehler L; Institute of Biology II, Albert Ludwig University of Freiburg, 79104 Freiburg, Germany; Institute of Hydrobiology, Technische Universität Dresden, 01217 Dresden, Germany., Flemming FE; Institute of Biology II, Albert Ludwig University of Freiburg, 79104 Freiburg, Germany., Schrallhammer M; Institute of Biology II, Albert Ludwig University of Freiburg, 79104 Freiburg, Germany. Electronic address: martina.schrallhammer@biologie.uni-freiburg.de.
Jazyk: angličtina
Zdroj: European journal of protistology [Eur J Protistol] 2019 Apr; Vol. 68, pp. 108-120. Date of Electronic Publication: 2019 Feb 12.
DOI: 10.1016/j.ejop.2019.02.002
Abstrakt: Paramecium strains with the ability to kill other paramecia often harbour intracellular bacteria belonging to the genera Caedibacter or Caedimonas. Central structures of this killer trait are refractile bodies (R-bodies) produced by the endosymbionts. Once ingested by a sensitive Paramecium, R-bodies presumably act as delivery system for an unidentified toxin which causes the death of endosymbiont-free paramecia while those infected gain resistance from their symbionts. The killer trait is therefore considered as competitive advantage for the hosts of R-body producers. While its effectiveness against paramecia is well documented, the effects on other aquatic ciliates are much less studied. In order to address the broadness of the killer trait, a reproducible killer test assay considering the effects on predatory ciliates (Climacostomum virens and Dileptus jonesi) as well as potential bacterivorous Paramecium competitors (Dexiostoma campyla, Euplotes aediculatus, Euplotes woodruffi, and Spirostomum teres) as possibly susceptible species was established. All used organisms were molecularly characterized to increase traceability and reproducibility. The absence of any lethal effects in both predators and competitors after exposure to killer paramecia strongly suggests a narrow action range for the killer trait. Thus, R-body producing bacteria provide their host with a complex, costly strategy to outcompete symbiont-free congeners only.
(Copyright © 2019 Elsevier GmbH. All rights reserved.)
Databáze: MEDLINE
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