First stand of Paramecium octaurelia in Europe and molecular characteristics of other known strains of this species.

The first stand of Paramecium octaurelia in Europe (Germany) is described and interesting intra-specific polymorphism is compared within the species using strains originating from different continents (Europe, N. America and Asia). Sequenced fragments of 5' LSU rDNA and COI mtDNA revealed that the studied strains form two groups, one with strains from Germany and USA, and a second group from Israel.

Competitive advantages of Caedibacter-infected Paramecia.

Intracellular bacteria of the genus Caedibacter limit the reproduction of their host, the freshwater ciliate Paramecium. Reproduction rates of infected strains of paramecia were significantly lower than those of genetically identical strains that had lost their parasites after treatment with an antibiotic. Interference competition occurs when infected paramecia release a toxic form of the parasitic bacterium that kills uninfected paramecia.