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1.
SYNOPSIS The effects of synchronizing temperatures on RNA metabolism in 2 strains of Tetrahymena pyriformis have been studied. High temperature shifts cause degradation of unstable RNA fractions, including whole cell RNA and nuclear RNA. The evidence indicates that this hydrolysis results in a net loss of unstable RNA during each temperature shift and, indirectly, to an inhibition of uptake2 of extra-cellular RNA precursors. The destruction of unstable RNA appears random; no evidence for stable template pools was found. In addition, both indirect in vivo and direct in vitro assays of RNA polymerase activity failed to reveal any inhibition by synchronizing heat shifts. The inhibition of precursor incorporation in vivo apparently stems from a lag in the uptake of label into the intracellular nucleotide pools. The temperature values required to induce net hydrolysis of unstable RNA correlate well with those required for synchronization for each strain. 相似文献
2.
Feeding of planktonic rotifers on ciliates: a method using natural ciliate assemblages labelled with fluorescent microparticles 总被引:1,自引:0,他引:1
Joaquim-Justo Celia; Detry Cedric; Caufman Fabrice; Thome Jean-Pierre 《Journal of plankton research》2004,26(11):1289-1299
A method was developed to allow direct measurements of predationexerted by metazooplankton on ciliates. The method relied onthe use of ciliates labelled with fluorescent microparticles(FMP). Optimal labelling conditions were determined with ciliatesfrom cultures (Tetrahymena pyriformis) and with natural ciliateassemblages sampled in a river. Labelled T. pyriformis wereused as tracer food to determine gut passage time (GPT) andingestion rates of the rotifer Brachionus calyciflorus in thelaboratory. Predation of metazooplankton from the lowland riverMeuse (Belgium) was determined by labelling natural assemblagesof ciliates and using them as tracer food for metazooplankterssampled in the river. Optimal labels of ciliates, i.e. sharpdistribution of FMP in cells, were obtained with short incubations(10 min) and low FMP concentrations (1 x 105 mL1). GPTvaried between 30 and 45 min for B. calyciflorus and from 25up to >35 min for rotifers from the river. The ingestionrate of B. calyciflorus fed with T. pyriformis was 3.3 ±0.6 ciliate rot1 h1, i.e. 1.4 ± 0.3 ngCrot1 h1. Metazooplankton species for which theingestion of ciliates could be measured were the rotifers Keratellacochlearis, Euchlanis dilatata and Synchaeta spp. Ingestionrates measured ranged from 0.4 to 12.5 ngC rot1 h1.The method proposed proved to be useful in estimating the predationof microplankton on ciliates in semi- in situ conditions; infurther developments, labelled natural assemblages of ciliatescould be used for in situ incubations with the Haney chamber. 相似文献
3.
A. Frisch H. Levkowitz A. Loyter 《Biochemical and biophysical research communications》1976,72(1):138-145
Tunicamycin, a glucosamine-containing antibiotic inhibited the conjugation process of Tetrahymena pyriformis. Sexual pairing was prevented completely when 1.5 μg/ml of tunicamycin was added to a mixture of the two mating types. Tunicamycin caused preferential inhibition of glycoprotein synthesis in Tetrahymena pyriformis. At 1.5 μg/ml and 6 μg/ml tunicamycin inhibited by 40% and 60% respectively [3H]-glucosamine incorporation into material precipitated by ethanol, while it did not affect [14C]-leucine incorporation. Cell division was also inhibited when the drug was added either to the regular growth medium or to the starvation medium. 相似文献
4.
JOHN A. NICOLETTE HOWARD E. BUHSE MARTIN S. ROBIN 《The Journal of eukaryotic microbiology》1971,18(1):87-90
SYNOPSIS. Differentiation of small-mouthed cells (microstomes) into large-mouthed, potentially carnivorous cells (macrostomes) in Tetrahymena vorax is prevented by 2-mercapto-1-(β-4-pyridethyl) benzimidazole (MPB). This differentiation, induced by the transforming principle, stomatin, isolated from the potential prey, Tetrahymena pyriformis, is a synchronous process in which 70–95% of the population of T. vorax microstomes transform into macrostomes within 450 min. MPB also inhibits RNA synthesis in transforming microstomes while having little effect on protein synthesis. Finally, the effect of MPB on both transformation and RNA synthesis is reversible. 相似文献
5.
Ching-Fun Chang Akira Isogai Toshiya Kamikado Shigeo Murakoshi Akira Sakurai Saburo Tamura 《Bioscience, biotechnology, and biochemistry》2013,77(5):1167-1168
A cadmium and zinc-binding protein similar to metallothionein has been isolated from Tetrahymena pyriformis exposed to cadmium chloride. This protein contained 32.4% half-cystine, 23.7% acidic amino acids and 10.1% lysine. The amino acid composition was similar to that of copper-thionein of yeast. The metal-binding protein of Tetrahymena pyriformis contained 3.7 g atom cadmium, 0.7 g atom zinc, and O.l g atom copper per mol, and shpwed the spectral characteristics of cadmium-thionein, i.e., a broad shoulder at 250 nm and low residual absorption at 280 nm. The molecular weight of this protein was determined to be 11,000 by gel filtration in 6 M guanidine hydrochloride, although it moved like a protein with a molecular weight of 30,000 on ordinary gel filtration. 相似文献
6.
《Cell biology international reports》1981,5(11):1019-1026
Exponentially multiplying cultures of the fission yeast Schizosaccharomyces pombe were treated with a peptide factor obtained from the protozoan Tetrahymena pyriformis. It was found that the rate of RNA synthesis was reduced by this factor, whereas cell multiplication and protein synthesis were unaffected. These results confirm previous results obtained with protoplasts of the same yeast. 相似文献
7.
《Cell differentiation》1981,10(4):237-242
The activities of enzymes responsible for cyclic nucleotide synthesis and degradation were studied during growth of Tetrahymena pyriformis, strain GL. The significant changes in the enzyme activities involving the cyclic GMP system were observed. Moreover, a close relationship was found to exist between the guanylate cyclase activity and the calmodulin level. While the guanylate cyclase activity was greatly diminished by trifluoperazine, a potent inhibitor of calmodulin, the activities of other enzymes were unaffected. These results suggest that the guanylate cyclase activity may be regulated by calmodulin level during growth in T. pyriformis. 相似文献
8.
The succinate analog itaconic acid was observed to be a competitive inhibitor of the glyoxylate cycle specific enzyme isocitrate lyase (EC 4.1.3.1) in cell-free extracts of Tetrahymena pyriformis. Itaconic acid also inhibited net in vivo glycogen synthesis from glyoxylate cycle-dependent precursors such as acetate but not from glyoxylate cycle-independent precursors such as fructose. The effect of itaconic acid on the incorporation of 14C into glycogen from various 14C-labeled precursors was also consistent with inhibition of isocitrate lyase by this compound. Another analog of succinate which shares a common metabolic fate with itaconic acid, mesaconic acid, had no effect on isocitrate lyase activity in vitro or on 14C-labeled precursor incorporation into glycogen in vivo. In addition, itaconic acid did not affect gluconeogenesis from lactate in isolated perfused rat livers, a system lacking the enzyme isocitrate lyase. These results are taken as evidence that itaconic acid is an inhibitor of glyoxylate cycle-dependent glyconeogenesis Tetrahymena pyriformis via specific competitive inhibition of isocitrate lyase activity. 相似文献
9.
The alteration of the content of heat-shock protein 70 kDa (Hsp70) was studied in cells of the freshwater ciliate Tetrahymena pyriformis after the salinity of the medium had been changed. It was shown that ciliates acclimated to fresh (0%) or salt (2 and 10%) water have similar levels of constitutive Hsp70. Neither pronounced induction nor a decrease in the Hsp70 level were revealed in ciliates after salinity stress. These data differ from the results we obtained previously with more euryhaline ciliates, Paramecium nephridiatum and P. jenningsi. In those species, we observed both the induced synthesis of Hsp70 after salinity stress and changes (decrease or increase) in the constitutive Hsp70 level after the acclimation of ciliates to the altered medium salinity. We presume that the differences in the chaperone system reaction of these ciliates species may be connected with their different salinity resistances, least of all in P. jenningsi, intermediate in T. pyriformis, and most pronounced in P. nephridiatum. 相似文献
10.
Ren-Huan Tang Min-Min Su Tong-Geng Cao Yuan-Fang Liu 《Biological trace element research》1985,7(2):95-102
Using two Chinese strains ofTetrahymena pyriformis, S1 and BJ4, as the biological models, the effects of lighter rare earths (lanthanum, cerium, praseodymium, neodymium, samarium, and europium), representatives of heavier rare earths (yttrium and thulium), and mixed rare earths were studied. The stimulation of population growth ofTetrahymena in peptone-glucose media containing trace amounts of these elements have been observed. The mechanisms for the beneficial effects of rare earth elements in low concentrations remains to be discovered. 相似文献
11.
《Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism》1979,572(2):376-381
The usual rise in phospholipid-bound palmitoleic acid of Tetrahymena pyriformis cells slowly acclimating to low temperature exposure can be prevented by cycloheximide. This reduction in fatty acid desaturation is not caused by specific inhibition of a temperature-induced synthesis of a fatty acid desaturase but rather by a general effect equally conspicuous in isothermal cells. Cycloheximide-inhibited cells chilled and analyzed quickly, before long term ill effects of the drug are expressed, exhibit the rise in unsaturated fatty acids typical of temperature-acclimating cells. 相似文献
12.
Yuan-Fang Liu Ren-Huan Tang Qing-Xi Zhang Jin-Yuan Shi Xiao-Ming Li Zhao-Qing Liu Wei Zhao 《Biological trace element research》1986,9(2):89-99
Tetrahymena pyriformis, S1 andBJ11, andChlamydomonas reinhardtii CR were employed to study the stimulation of cell proliferation induced by a number of elements. It was observed that traces of Ga, As, Se, Rb, Sr, Ag, Sn, Cs, Yb, Re, and Ir promote the population growth ofT. pyriformis in peptone-glucose culture media or chemically defined media. Inhibition effects onT. pyriformis were observed in media containing traces of In, Te, ba, T1, and Pb. UsingCh. reinhardtii CR, the stimulation effects induced by trace amounts of Ga, Ge, As, Cs, La, Ce, Re, and Ir, respectively, were also determined. Concentration ranges of trace elements promoting cell proliferation are given. 相似文献
13.
Driss Mountassif Mostafa Kabine Rachid Manar Noureddine Bourhim Zaina Zaroual Norbert Latruffe MHammed Saïd El Kebbaj 《Ecological Indicators》2007,7(4):882-894
The individual cytotoxicity of cadmium chloride, iron sulphate and chromium nitrate has been investigated by using the freshwater ciliate Tetrahymena pyriformis. The metabolic enzymes and antioxidant defense biomarkers were assessed. The results obtained reveal that their metal salts have perturbed the physiology and morphology of T. pyriformis. Also, the biomarkers assessed were sensitive to the presence of metal salts and this sensitivity was metal salt and dose dependant. To estimate the impact of their metal salts on mitochondria, we studied their effects in vivo and in vitro on the d-β-hydroxybutyrate dehydrogenase (BDH) (EC 1.1.1.30) inner mitochondrial membrane enzyme. The results showed a high inhibition of BDH in terms of activity, protein expression and kinetic parameters. 相似文献
14.
In the protozoan Tetrahymena pyriformis the DNA synthesis is stopped immediately and completely after addition of one of the two DNA synthesis inhibitors methotrexate + uridine and hydroxyurea to a cell suspension. However, the present experiments show, that the accumulation of labeled H1 histone in the inhibited cells is almost totally unaffected for more than two-thirds of a cell cycle after addition of either inhibitor. 相似文献
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17.
Selivanova G. V. Shemarova I. V. Vlasova T. D. 《Russian Journal of Developmental Biology》2002,33(6):374-377
We studied the effect of murine epidermal growth factor on cell proliferation and DNA synthesis in macronuclei of ciliate Tetrahymena pyriformis Gl. Mitogenic effect of epidermal growth factor on proliferation-induced tetrahymena cells has been revealed. This effect is due to the induced progression of cells at G
1 and, consequently, their earlier entering DNA synthesis phase of the first cell cycle. Epidermal growth factor had no mitogenic effect on the resting cells in a stationary culture (G
0 phase) whose development is independent of the growth factors in the medium. 相似文献
18.
THE FINE STRUCTURE OF THE NUCLEI OF TETRAHYMENA PYRIFORMIS THROUGHOUT THE CELL CYCLE 总被引:10,自引:7,他引:3
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Charles J. Flickinger 《The Journal of cell biology》1965,27(3):519-529
The fine structure of the nuclei of logarithmically growing Tetrahymena pyriformis, strain HSM, was studied at 30-minute intervals throughout the cell cycle. Organisms were selected at similar stages of cytokinesis by means of a braking pipette, incubated, fixed in OsO4, and embedded in agar to facilitate subsequent preparation for electron microscopy. Aggregates of micronuclear chromatin underwent a decrease in density and number with a concomitant increase in size throughout interphase. There were no impressive changes in macronuclear morphology. It was found possible to estimate a cell's progress through interphase by observation of micronuclear morphology, but attempts to correlate changes in fine structure with periods of DNA synthesis were unsuccessful. 相似文献
19.
STUDIES OF MEMBRANE FORMATION IN TETRAHYMENA PYRIFORMIS : III. Lipid Incorporation into Various Cellular Membranes of Logarithmic Phase Cultures
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When 1-14C-palmitic acid is used to pulse label logarithmic cultures of Tetrahymena pyriformis, radioactivity appears in lipids of the various membrane types at vastly differing rates. The microsomes and postmicrosomal supernatant attain a high specific radioactivity within 1 min, while the membranes enveloping the cilia require several hours to reach the microsomal level. A similar pattern is obtained when the tracer is sodium 1-14C-acetate or 8,9-3H-hexadecyl glycerol. In all fractions the phosphonolipid incorporates radioactivity from 14C-palmitate much less rapidly than do the other major phospholipids. The patterns of labeling suggest that new lipids are transported from a cytoplasmic site of synthesis to points of membrane fabrication throughout the cell. 相似文献
20.
Nelson Slavik Lana Stolarsky Charles L. Hershberger 《Journal of molecular evolution》1975,4(4):371-376
Summary DNA from nuclei ofTetrahymena pyriformis was examined by equilibrium density gradient ultracentrifugation at alkaline pH. The results indicate that the DNA has a uniform distribution of guanine plus thymine in the complementary strands and throughout the nucleotide sequence of the DNA.Abbreviations cDNA
chloroplast DNA isolated fromEuglena gracilis
- nDNA
DNA isolated from nuclei ofTetrahymena pyriformis 相似文献