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At least 955 records · Page 53Linked to original sources
PubMed1990

Effects of angular speed in responses of Paramecium tetraurelia to hypergravity.

The paper shows the results of investigations carried out in a single cell organism. Paramecium tetraurelia exposed to different gravitational levels. Hypergravity resulted in a decrease in cell growth rate. The responses depend on g level and angular speed of the centrifuge; furthermore they depend also on small short fluctuations in g levels, delta g, due to the swimming of the cells inside the culture tubes. Delta g depends on angular speed and size of the holding device. The inhibitory effect of hypergravity, for the same angular speed, increases with respect of the diameter of the culture tubes.

Animals↗
PubMedDate not supplied

[Characteristics of the cytodifferentiation of omega-particle symbiotic bacteria from the micronucleus of Paramecium caudata clone M1-48].

The structure of the omega-particle-bacteria, growing in the micronucleus of Paramecium caudatum (Ciliata, Protozoa), was studied by electrom microscopy in the course of their life cycle. The cytoplasm of the spindle-shaped vegetative cells contains a large number of dense particles and transparent regions comprising the fibrillar material. Such cells, via several intermediate stages, are transformed into elongated twisted cells that are regarded as spores. The spore consists of two parts: homogeneous, and that containing the membrane system and rounded light bodies. The membranes are often double and connected with the fibrils. The cell wall is constructed, during all stages, of the outer membrane layer and the inner electron-dense layer.

Bacteria↗
PubMed1975

[Effect of local UV microirradiation on the nuclear apparatus and cytoplasm of the infusorian Paramecium caudatum].

The work is the first attempt to study nuclear dualism of ciliates with ultraviolet microbeam (UV-beam), which was not applied earlier for these purposes. The special advantage of the UV-beam is that it allow to inactivate selectively of the particular elements of nuclear apparatus of living ciliates is to observe consequences of operation on distant descendants of irradiated cell. On Paramecium caudatum the ways of UV-beam have been devised specifically. The original rotocompression chamber was employed for immobilization of cell in space of irradiation. The effective UV-doses were selected, the relative resistance of cytoplasm, macro-, micronucleus (Mi), and symbiotic bacteria of Mi -- omega particles -- was detected. The "pure" and infected cells were irradiated, in some different variants. The effect of UV-beam depends on dose and consists in a reduction the effectiveness of cell cloning, the loss of omega-particles from Mi, the appearance of the cells with 2--3 Mi, and, possibly, of amicronucleate cells. The injuries due to UV-beam are restored by photoreactivation of visible light.

Cell Nucleolus↗
PubMed1975

[Effect of a varying concentration of boron on the tempo of Paramecium caudatum multiplication depending on the temperature of the medium].

The rate of multiplication of Paramecium caudatum was studied using individual cultures with media containing 0.001, 0.005, 0.008 and 0.01% borate, resp. At room temperature (20--21 degrees C) with two first concentrations of boron, the ciliates multiply normally over 4 months often surpassing the multiplication rate of the control line. With the increase of boron concentration up to 0.008%, the division rate in paramecia decreases significantly, reaching the control rate only by the end of the 3rd month. At high temperature (26--27 degrees) with 0.001 and 0.005% of boron in the media, P. caudatum was also seen to multiply normally. At lower temperature (15--17 degrees) all the test concentrations of borate used decreased the rate of division, and the higher the concentration of boron the more pronounced was the depressing effect.

Boron↗
PubMed2001

Anomalies of autogamy in Paramecium tetraurelia temperature sensitive mutant induced by heat treatment.

The run of autogamy in temperature sensitive mutant ts401, carrying also the mutation of trichocysts nd3a, at permissive (26 degrees C) and non-permissive temperature (35 degrees C) was studied and compared with this process in wild d4-2 stock of Paramecium tetraurelia. The effect of heat treatment on programmed nuclear and cortical events was investigated using cytological silver impregnation Fernandez-Galiano method and immunofluorescence technique with the application of two anti-alpha-tubulin antibodies. The appearance of cells with some large macronuclear fragments and an excess number of micronuclei suggests that nuclear differentiation is inhibited at restrictive temperature and that macronuclear regeneration takes place in this thermosensitive mutant. In such cells impaired oral reorganization was observed. After slight refeeding at the late autogamy, cells stopped at first postautogamous division were induced by heat treatment. The most striking feature of these abnormal divisions was the lack of a basal body duplication wave, which suggests that production of gamma-tubulin, structural protein being the essential component of the microtubule organizing centres, is disturbed at high temperature.

Animals↗
PubMed2001

The effects of the ciliate Paramecium cf. caudatum Ehrenberg on toxin producing Cylindrospermopsis isolated from the Fitzroy River, Australia.

The large ciliate Paramecium cf. caudatum Ehrenberg was found to be a successful grazer of toxin producing Cylindrospermopsis in the laboratory. The feeding rate increased with increasing cell concentration to 1367 cell animal hr-1 at 4.1 x 10(5) cells mL-1 but declined slightly at cell concentrations greater than this. Preliminary studies on the effects of this grazing on toxin concentrations in cultures of both straight and coiled forms of Cylindrospermopsis resulted in the production of different amounts of the toxin cylindrospermopsin in the different isolates. Differences in toxin production were also found between cultured and field populations from the lower Fitzroy River indicating that toxin production may be influenced by a suite of genetic and environmental factors. The proven ability of this ciliate to graze toxic Cylindrospermopsis provides some insight into interactions that may be able to control some toxic blooms in semiarid Australian conditions.

Alkaloids↗
PubMed2001

Effect of wild-type macronucleoplasm transplantation into trichocyst mutant cells of Paramecium tetraurelia.

Approximately 1/2 of the macronucleoplasm of wild-type cells of Paramecium tetraurelia was transplanted into d4-84 mutant recipient homozygous for mutations nd3a (non-discharging trichocysts) and ts401 (temperature sensitive). After injection, 30% of surviving cells shifted from mutant to wild-type phenotype. Among the remaining cell lines 29% were unable to eject any trichocysts, and 41% discharged less than 10 of them per cell, when tested with picric acid. Observations were made through two successive vegetative fissions. These results showed that 30% of d4-84 cells contained foreign gene responsible for trichocyst discharge and produced cell lines of the wild-type phenotype, in which the expression as well as replication of this gene appeared normal.

Animals↗
PubMed2002

[Effect of symbiotic algae on the photoaccumulation capacity of cells of the ciliate Paramecium bursaria].

The character of the effect produced by symbiotic algae on photodependent behavior of their host ciliates, Paramecium bursaria, was determined. Partially alga-freed paramecia showed a reliable increase in the rates of photoaccumulation. The photoaccumulation rate gradually decreased with a further decrease in the number of zoochlorellae. Once the chlorophyll content fell down to 20-25 mu/l, the ciliates lost their capacity for photoaccululation. A mathematical model of photoaccumulation has been constructed.

Animals↗
PubMed2002

[The route of a bacterium Holospora in the cell of Paramecium (Ciliophora, Protista) from phagosome to the nucleus].

Problems encountered at the initial stages of stable symbiotic system formation are discussed in the review. The most studied models for interaction between pathogenic bacteria and metazoan cells are compared with a similar system including Paramecium (a ciliatte)--Holospora (a bacterium). Literary and our own data on the infection of P. caudatum with specific endocytobionts inhabiting the nuclear apparatus (H. obtusa in the macronucleus), and H. undulata (in the micronucleus) are analysed with respect to the modern understanding of the intracellular vesicle trafficking.

Animals↗
PubMed2002

Paramecium biaurelia--relation of strains.

Inter- and intra-strain crosses were made in Paramecium biaurelia of the P. aurelia species complex for studying the relation of strains within the species. Altogether ten strains originating from Scotland, Spain, Romania, Czech Republic, Ukraine, Italy, Germany, Russia, and Poland (two strains) were studied. A high percentage of surviving clones in both generations, F1 (obtained by conjugation) and F2 (obtained by autogamy), was observed in strain crosses, indicating a strong relation between the strains, and absence of genetic barriers between them in P. biaurelia.

Animals↗
PubMedDate not supplied

[Macronuclear DNA and total protein contents of mating types I and II of Paramecium primaurelia, during the phase of maturity and the transition to senescence. Preliminary observations].

Concerning the studies on mating type differentiation and life cycle development in Paramecium primaurelia stock 90, both macronuclear DNA and total protein contents have been measured cytofluorometrically in mating type I and mating type II isogenic cell lines growing in logarithmic phase, throughout their maturity period and transition to senescence. The target was to investigate whether the two mating types undergo clonal decline in different times, as the previous studies suggested. The results indicate that, throughout the maturity period, macronuclear DNA and total protein contents vary both in mating type I and mating type II cell lines; moreover, aged phenotypes as the dramatic decrease of both contents, firstly occur in mating type II which, therefore, appears to be submitted to clonal decline before mating type I.

Aging↗
PubMedDate not supplied

Food ingestion and egestion in mating reactive populations of Paramecium primaurelia.

The study of food ingestion and egestion carried out on Paramecium primaurelia mating reactive cells shows that, after their transfer into a medium with suspended particles, the complementary mating type cells exhibit very significant differences in the food vacuole formation and egestion rate. Under the same external environmental conditions, the mating type II cells form and egest a higher number of food vacuoles when compared with mating type I cells. The higher rate of food vacuole formation shown by the mating type II cells is related to their faster growth rate.

Animals↗
PubMed1992

Toxicity of Fastac 10 EC, a pyrethroid insecticide, to Paramecium primaurelia and Tubifex sp.

The pyrethroide, Fastac 10 EC was tested on the paramecia and Tubifex sp. The results showed that both tests are valid for estimation of the toxicity of the pesticide. However, the Paramecium test is more sensitive when one is investigating the direct toxicity of the compound. The great validity of the Tubifex test lies in the possibility of tracing the teratogenic effects of the pesticides.

Animals↗