It has been known for many years that electric currents flowing through a suspension of Paramecium modify the beating characteristics of the cilia in such a way that the organisms turn and move towards the cathode (Ludloff, 1895; Jennings, 1906). Jahn (1961) has accounted for this behaviour by supposing that current flows through the cell membrane and either enhances or reverses the normal cili...

M A T I N G type determination and inheritance in Paramecium caudatum has been reported only for syngen 12 (HIWATASHI 1958). Inheritance was usually synclonal, i.e. the two clones derived from the two members of a conjugating pair are identical in mating type expression, indicating direct genic control of mating type. However the breeding analysis was incomplete and some of the observations, as...

The membrane potential responses of Paramecium caudatum to the external application of bitter substances were examined by employing conventional electrophysiological techniques. Mutant cells defective in voltage-gated Ca2+ channels were used to record the potential responses in the absence of contamination by Ca2+ action potentials. The cells produced a transient depolarization followed by a tr...

1. The effects of KCN and iron salts on oxygen consumption has been studied in the cell of Paramecium caudatum by manometric methods. 2. KCN solutions of strengths from M/200 to M/10,000 have been shown to produce no decrease in oxygen consumption, but have in most cases produced a very slight increase in the respiration rate. 3. The pH values were found to have little or no effect on these res...

Binding of (45)Ca by live Paramecium caudatum was determined under various external ionic conditions. It was found that calcium uptake was separable into at least two components, a rapid and a slow one. The rapid component was influenced by the presence of certain other ions in a manner which agrees with the law of mass action. It appears that an ion exchange system may be involved in a binding...

We investigated nitric oxide (NO) production in Paramecium caudatum, and the role of NO production in population growth in culture and thermoregulation. Nitrite (NO2 -) concentration in media containing P. caudatum [6350 ± 390 (SD) paramecia/ml] was 2.37 ± 0.53 μM after 6 h, compared to 0.16 ± 0.06 μM in media alone (p<0.005), and the NO synthase (NOS) inhibitor, Nω-nitro-L-arginine methylester...

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...

In parasites with mixed modes of transmission, ecological conditions may determine the relative importance of vertical and horizontal transmission for parasite fitness. This may lead to differential selection pressure on the efficiency of the two modes of transmission and on parasite virulence. In populations with high birth rates, increased opportunities for vertical transmission may select fo...

1. The quantitative relationship between chemoaccumulation and locomotor activity in specimens of Paramecium caudatum was examined by employing a novel chemoaccumulation assay system. 2. Distribution of the specimens in two adjoining solutions with different chemical compositions was dependent on both the rate of arrival of the specimens at the border between two solutions (the arrival rate) an...

Information transfer is a fundamental of life. A few studies have reported that cells use photons (from an endogenous source) as information carriers. This study finds that cells can have an influence on other cells even when separated with a glass barrier, thereby disabling molecule diffusion through the cell-containing medium. As there is still very little known about the potential of photons...