Endosymbioses are driving forces underlying cell evolution. The endosymbiosis exhibited by Paramecium bursaria is an excellent model with which to study symbiosis. A single-cell microscopic analysis of P. bursaria reveals that endosymbiont numbers double when the host is in the division phase. Consequently, endosymbionts must arrange their cell cycle schedule if the culture-condition-dependent ...

The survival or degeneration of nuclei produced after meiosis in Paramecium caudatum depends upon their position in the cytoplasm. The surviving nucleus lies in the paroral region, which is the region around the cytostome. In this study, this was confirmed by quantitative measurements of the location of surviving nuclei in both stained and living conjugating cells. Observation of nuclear behavi...

Fertilization process of Paramecium caudatum includes a reciprocal exchange of migratory pronuclei across a temporary junction between conjugating cells. To know the role of microtubules on the behavior of pronuclei during conjugation in P. caudatum, the localization of microtubules was investigated by indirect immunofluorescence with a monoclonal anti-a-tubulin antibody. The immunofluorescence...

Two types of Triton X-100 extracted model of Paramecium caudatum were prepared and effects of the ionic compositions of the reactivating medium on the swimming behaviour of the extracted models were examined. Type I, prepared by the method of Naitoh and Keneko, did not change swimming direction depending on the concentrations of Mg2+ and K+ in the reactivating medium. Type II, prepared by a dif...

Parafusin, the major protein in Paramecium tetraurelia to undergo dephosphorylation in response to secretory stimuli, appears to be the primary acceptor for the glucosylphosphotransferase in this species based on five independent criteria: identical molecular size of 63 kD; identical isoelectric points in the phosphorylated state of pH 5.8 and 6.2; identical behavior in reverse-phase chromatogr...

Transmembrane channels have been found in the membrane fraction of corn (Zea mays W64AN) mitochondria that exhibit a remarkable resemblance to the voltage dependent anion-selective channels (VDAC) located in the outer membrane of animal (Rattus norvegicus), protist (Paramecium aurelia), and fungal (Neurospora crassa) mitochondria. The channels in corn were demonstrated to be essentially identic...

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...

Critical review of research methods for tolerance and potential tolerance of ciliates is given. Using several Paramecium species as an example the original approaches to potential tolerance estimation is presented. Connection between resistance, tolerance and potential tolerance is shown. Model for explanation of the connection is proposed. Several application aspects of diagrams of the connect...

The molecular size of mu and pi symbionts of Parameciumaurelia has been calculated from renaturation kinetic data. Observed values were 0.78 x 10(9) daltons for mu particle DNA and 0.81 x 10(9) daltons for pi particle DNA. Estimates of analytical complexity were 4.45 x 10(9) and 5.05 x 10(9) daltons respectively. Based on these data, mu and pi symbionts appear to possess multiple genomes and co...