Parasitic infection can modify host mobility and consequently their dispersal capacity. We experimentally investigated this idea using the ciliate Paramecium caudatum and its bacterial parasite Holospora undulata. We compared the short-distance dispersal of infected and uninfected populations in interconnected microcosms. Infection reduced the proportion of hosts dispersing, with levels differi...

Membrane vesicles with a high mating reactivity were obtained from cilia of Paramecium caudatum by treatment with a solution containing 2 M urea and 0.1 mM Na2-EDTA. All processes of conjugation were induced in cells of the complementary mating type by approximately 10 mug/ml proteins of the vesicles. Electron microscope observation showed that the membrane vesicles have a diameter of 100-150 n...

The gram-negative bacterium Holospora obtusa is an endonuclear symbiont of Paramecium caudatum, which is incorporated into the host cells via the food vacuoles and infects their macronucleus exclusively, but never the micronucleus. Since these two kinds of nuclei originate from a fertilization nucleus, it is assumed that the macronucleus acquires a property necessary for it to be recognized by ...

The effects of pulse laser irradiation on the cortex of Paramecium caudatum and Blepharisma undulans undulans were studied. The character and extent of cortical injury was video recorded and subsequently analyzed. Destruction of the cytoskeleton by laser irradiation was detected by immunofluorescence staining. A difference in the development and healing of the wound was observed between Paramec...

The Hb (hemoglobin) content of Paramecium has been known to maintain a constant level even when the cells are exposed to different conditions. However, the relative concentrations of the Hb components in the stocks of P. caudatum, P. multimicronucleatum and P. jenningsi were found to change during cell growth from logarithmic young phase to stationary growth phase even when the culture was main...

Understanding and quantifying the temperature dependence of population parameters, such as intrinsic growth rate and carrying capacity, is critical for predicting the ecological responses to environmental change. Many studies provide empirical estimates of such temperature dependencies, but a thorough investigation of the methods used to infer them has not been performed yet. We created artific...

Clonal herbs that attain maximum development in late-seral forest are often assumed to have similar responses to disturbance and to be functionally equivalent. However, little is known about the demographic or physiological responses of these plants to disturbance or to the altered conditions of the post-disturbance environment. Following harvest of a mature coniferous forest, we compared abund...

Many organisms use cues to decide whether to disperse or not, especially those related to the composition of their environment. Dispersal hence sometimes depends on population density, which can be important for the dynamics and evolution of sub-divided populations. But very little is known about the factors that organisms use to inform their dispersal decision. We investigated the cues underly...