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...

1. Analysis of the division rates of Paramecium aurelia (mutant), Blepharisma undulans, and Histrio complanatus grown separately in pedigree isolation culture with the same culture medium, and in the same room at any given time, for a period of 3 years, discloses a secular trend and a seasonal rhythm for each organism. The seasonal rhythm is a yearly cycle with a maximum during July. 2. After r...

The electric properties of Paramecium have gained interest because of the emerging role of membrane potential and conductance in the control of ciliary activity (Kinosita, 1954; Okajima, 1953; Naitoh, 1958; Kinosita, Murakami & Yasuda, 1965; Naitoh & Eckert, 1969a, b; Eckert & Naitoh, 1970). Recent evidence indicates that ciliary responses are coupled to membrane potential by membrane-regulated...

Environmental fluctuations are important for parasite spread and persistence. However, the effects of the spatial and temporal structure of environmental fluctuations on host-parasite dynamics are not well understood. Temporal fluctuations can be random but positively autocorrelated, such that the environment is similar to the recent past (red noise), or random and uncorrelated with the past (w...

The kinetics of gravitaxis and gravikinesis in Paramecium caudatum were investigated by employing (1) step transitions from normal gravity (1 g) to weightlessness (microgravity) and (2) turns of the experimental chambers from the horizontal to the vertical position at 1 g. The transition to microgravity left existing cell orientations unchanged. Relaxation of negative gravitaxis under micrograv...

The non-Mendelian mutant d48 of Paramecium tetraurelia contains micronuclear wild type A genes, but at autogamy and conjugation proper processing fails and new macronuclei lack A genes. When cloned A genes are injected into the macronucleus of d48, proper processing is restored at the next autogamy; d48 is rescued, becoming permanently wild type. In the present study we have injected portions o...

The occurrence of species of the P. aurelia complex has been studied at a large scale in Europe and the majority of known species of the complex have been found there. However, a different number of habitats were studied in particular zones of Europe, the greatest number in the central zone. Herein new stands of several species of the Paramecium aurelia complex are presented from Europe includi...

learning is a cornerstone of intelligent behavior in animals. this behavior has been mostly studied in organisms with a fairly complex nervous system. however, recent reports of learning in unicellular organisms suggested the existence of associative learning in unicellular organisms. in particular, the capability to associate different light intensities with cathodal stimulation in paramecium ...

The presence of Paramecium sexaurelia from the Paramecium aurelia complex was recorded for the first time in China (Beijing). RAPD fingerprints (band patterns) of P. sexaurelia strains, the new strain from China and others from Asia, as well as from Europe and Puerto Rico, showed polymorphism within the species as several groups of genotypes characterized by different band patterns.