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At least 19 recordsLinked to original sources
PubMed1976

[The metabolic interactions between Paramecium bursaria Ehrbg. and Chlorella spec. in the Paramecium bursaria-symbiosis. II. Symbiosis-specific properties of the physiology and the cytology of the symbiotic unit and their regulation (author's transl)].

The endosymbiotic association of Paramecium bursaria Ehrbg. with Chlorella spec. (green Paramecium) was studied both physiologically and cytologically. Comparison of the properties of the symbiotic unit with those of the symbiotic partners which had been isolated from it revealed the following features and differences: 1. Up to 6000 lux the photosynthetic capacity of the symbiotic unit is higher than that of the isolated symbiotic algae grown independently in mass culture under defined conditions. Alga-free Paramecium bursaria (colourless Paramecium) show a very low rate of CO2-fixation. 2. The green Paramecium has a higher compensationpoint of photosynthesis (4000-5000 lux) than the isolated alga (200-400 lux). 3. Green paramecia consume less oxygen in darkness than colourless organisms but more than the isolated algae. 4. The uptake of carbohydrates from the culture medium by green parpmecia is lower than the uptake by alga-free P. bursaria but higher than the one of the isolated algae. 5. Symbiotic algae within the intact symbiotic unit show tightly packed photosynthetic membranes and an intense disposition of starch. In the presence of 3-(3,4-Dichlorophenyl)-1,1-dimethylurea (DCMU) or in darkness the arrangement of thylakoids is less compact and the deposition of starch is reduced. The growth and the number of the symbiotic algae in situ is regulated by a complex mechanism to which the intracellular level of carbohydrates belongs. The results are discussed in connection with ecological aspects of the Paramecium bursaria-endosymbiosis.

Animals↗
PubMed1976

[The metabolic interactions between Paramecium bursaria Ehrbg. and Chlorella spec. in the Paramecium bursaria-symbiosis. I. The nitrogen and the carbon metabolism (author's transl)].

Symbiotic Chlorellae have been isolated from Paramecium bursaria Ehrbg. and cultivated under conditions of nitrogen deficiency. Reinfection of Chlorella-free Paramecium bursaria with these nitrogen-deficient algae resulted in a complete regeneration and multiplication of the algae within the host cells. The endosymbiotic algal cells of the Paramecium bursaria-symbiosis can be supplied by their host with nitrogen. The inhibition of photosynthesis by 3-(3,4-Dichlorophenyl)-1,1-dimethylurea (DCMU) leads in green Paramecium bursaria to a breakdown of the symbiotic steady state-system resulting in a loss of algal cells. Obviously the endosymbiotic algae cannot be fed heterotrophically by their host to such an extent that a stable symbiosis is maintained. The application of 3-(3,4-Dichlorophenyl)-1,1-dimethylurea (DCMU) can be used as a new method for culturing Chlorella-free Paramecium bursaria.

Chlorella↗
PubMed1994

Effect of Paramecium biaurelia cytoplasm transplantation on the duration of the interautogamous interval (IAI) in Paramecium tetraurelia.

The cytoplasm of Paramecium biaurelia in various stages of IAI was transplanted to Paramecium tetraurelia cells of the same clonal age. Such donor cytoplasm was effective in retardation of the expression of autogamy in the recipient clones. The results suggest that the cytoplasm of Paramecium biaurelia may contain the autogamous immaturity factor whose level changes during the run of IAI and whose specificity is the same as in Paramecium tetraurelia.

Animals↗
PubMed1981

Organization and closing of mitochondrial deoxyribonucleic acid from Paramecium tetraaurelia and Paramecium primaurelia.

Previously we showed that the mitochondrial deoxyribonucleic acid (DNA) from Paramecium aurelia consists of a linear genome and that replication of this genome is initiated at one terminus and proceeds unidirectionally to the other terminus. Analyses of mitochondria from four closely related species (1, 4, 5, and 7) indicated that the species 1, 5, and 7 DNAs are essentially completely homologous but that the species 4 mitochondrial DNA is only 40 to 50% homologous with that from species 1. The major regions of homology are those containing the genes for ribosomal ribonucleic acid (RNA). To understand the replication and organization of the linear mitochondrial genome better, we compared species 1 (Paramecium primaurelia) and 4 (Paramecium tetraaurelia) DNAs with regard to restriction fragment mapping and homology between initiation regions; we also identified the sites of the genes for ribosomal RNA. In general, the structures of the species 1 and 4 mitochondrial genomes were quite similar. Each ribosomal RNA gene was present in one copy per genome, with the large ribosomal RNA gene located near the terminal region of replication and the small ribosomal RNA gene located more centrally. These two genes were separated by about 10 kilobases in the species 1 genome and by about 12 kilobases in the species 4 genome. In contrast to our previous findings, by using nonstringent hybridization conditions we detected homology between the species 1 and 4 DNA fragments containing the initiation regions. We constructed recombinant DNA clones for many fragments, especially those containing the initiation region and the ribosomal RNA genes. We also constructed restriction enzyme maps for six enzymes for both P. primaurelia and P. tetraaurelia.

Animals↗
PubMed1988

A new class of Paramecium surface proteins anchored in the plasma membrane by a glycosylinositol phospholipid. Membrane anchor of Paramecium cross-reacting glycoproteins.

Treatment of paramecia with ethanol or Triton X-100 solubilizes a major membrane protein, namely the surface antigen (SAg), and a set of glycopeptides in the range 40-60 kDa, which cross-react with the SAg. We demonstrate that these glycopeptides, called 'cross-reacting glycoproteins' (CRGs), are distinct molecules from the SAg. First, after purification of CRGs from ethanolic extracts of Paramecium primaurelia expressing the 156G SAg, the amino acid composition of a given CRG was found to be different from, and incompatible with, that of the 156G SAg. Secondly, we showed that the CRGs, although not immunologically detectable, are present in fractions containing the myristoylated form of the 156G SAg. The treatment of these fractions by phosphatidylinositol-specific phospholipases C enables us to reveal the CRGs through the unmasking of two distinct epitopes. One is the 'cross-reacting determinant' (CRD), initially described for the variant surface glycoproteins (VSGs) of Trypanosoma; the other determinant, called 'det-2355', is specific to the SAg and to the CRGs. Our results suggest that (1) phosphatidylinositol is covalently linked to the CRGs and (2) the CRD and the det-2355 are localized in the same region of the CRGs. We propose that the CRGs are a new set of surface proteins anchored in the cell membrane of Paramecium via a glycosylinositol phospholipid, in the same way as the SAgs.

Amino Acids↗
PubMed1986

Identification of the basal bodies and kinetodesmal fibers in living cells of Paramecium tetraurelia Sonneborn, 1975 and Paramecium sonneborni Aufderheide, Daggett & Nerad, 1983.

Critical use of Nomarski DIC optics and a rotocompressor permits basal bodies and kinetodesmal fibers to be visualized in the cortices of living Paramecium tetraurelia and Paramecium sonneborni. The identification of these structures is confirmed by the correspondence of the images obtained by DIC optics of living cells and by brightfield optics of fixed cells stained by the Fernández-Galiano silver technique. Examination of cells carrying cortical inversions (portions of the cortex rotated 180 degrees) shows that inverted regions may be identified and distinguished from normal regions by the orientation of the kinetodesmal fibers of the kinetids (cortical units) within the kineties (ciliary rows). This demonstrates that both the asymmetry and the polarity of each cortical unit may be assessed in the living cell. This technique has useful applications in the study of morphogenesis and patterning in living cells and for the screening of mutations and variants conferring altered cortical phenotypes.

Animals↗
PubMedDate not supplied

A method for the amplification of Paramecium micronuclear DNA by polymerase chain reaction and its application to the central repeats of Paramecium primaurelia G surface antigen genes.

This paper describes a method which allows the amplification of Paramecium micronuclear DNA. Amacronucleate cells are first obtained by an appropriate treatment with nocodazole, a microtubule depolymerizing agent which blocks the elongation of the macronucleus and the distribution of the micronuclei at cell division between the two daughter cells; then, DNA from such cells is amplified by the polymerase chain reaction technique. We have applied this method to the problem of the central repeats of the G surface antigen of P. primaurelia (strain 156). The central repeats consist of a 74 amino acid sequence repeated in tandem. The sequence identity of these repeats is also found in the nucleotide sequence even at silent codon positions, suggesting the existence of a mechanism of identity maintenance acting at the nucleotide level. Mechanisms based on RNA secondary structure which are frequently proposed as an explanation of this phenomenon are unlikely to be valid in this case. One can, therefore, imagine that these repeats might originate from one micronuclear sequence through duplicative processes which could occur during the formation of the macronucleus. We have used the described technique to amplify the micronuclear version of the central repeats and showed that it is identical to the macronuclear version, thus ruling out the above hypothesis. Therefore, intragenic recombination appears to be the most likely explanation of the sequence identity of these central repeats.

Amino Acid Sequence↗
PubMed2002

Paramecium tredecaurelia of the Paramecium aurelia complex in Israel.

The paper concerns the finding of a new habitat (Kiryat Motzkin, north of Haifa, Israel) of Paramecium tredecaurelia from the P. aurelia complex. This is only the forth known locality of the species in the world. Previously, its strains were obtained from widely separated localities: the River Seine, Paris, France; Benenitra, Madagascar, and the Cuernavaca Valley, Taxco, Mexico. The studied strain originating from Israel was identified as P. tredecaurelia on the basis of the strong (90%) conjugation between the complementary mating type of the examined clones with the appropriate standard strain 209 of P. tredecaurelia from Paris, France (restricted to odd mating type). However, the strain from Israel is restricted to the even mating type.

Animals↗