Generation times and reproductive rates of Amoeba proteus (Leidy) as influenced by temperature and food concentration

1980 ◽  
Vol 58 (4) ◽  
pp. 543-548 ◽  
Author(s):  
Andrew Rogerson
Keyword(s):  
Cell Cycle ◽  
Marked Effect ◽  
Tetrahymena Pyriformis ◽  
Food Concentration ◽  
Amoeba Proteus ◽  
Prey Concentration ◽  
Generation Times ◽  
Reproductive Rates

Temperature was found to have a marked effect upon the generation times of Amoeba proteus when cultured with Tetrahymena pyriformis at 20, 15, and 10 °C. The length of the cell cycle varied from 44 h at 20 °C to 2926 h at 10 °C. For each temperature studied, generation times followed a U-shaped distribution where the greatest division potential was determined by the prey concentration. Optimum reproductive rates were achieved at lower food levels as temperature was decreased. The results are discussed in the context of the available published literature.

The Chromatin Extrusion Phenomenon in Amoeba proteus Cell Cycle

2019 ◽  
Vol 67 (2) ◽  
pp. 203-208 ◽  
Author(s):  
Andrew V. Goodkov ◽  
Mariia A. Berdieva ◽  
Yuliya I. Podlipaeva ◽  
Sergei Yu. Demin
Keyword(s):  
Cell Cycle ◽  
Amoeba Proteus

scholarly journals THE FINE STRUCTURE OF THE NUCLEI OF TETRAHYMENA PYRIFORMIS THROUGHOUT THE CELL CYCLE

1965 ◽  
Vol 27 (3) ◽  
pp. 519-529 ◽  
Author(s):  
Charles J. Flickinger
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Fine Structure ◽  
Dna Synthesis ◽  
Tetrahymena Pyriformis ◽  
Concomitant Increase

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.

scholarly journals Effect of cell population density on G2 arrest in Tetrahymena.

1975 ◽  
Vol 67 (3) ◽  
pp. 518-522 ◽  
Author(s):  
I L Cameron ◽  
N C Bols
Keyword(s):  
Cell Cycle ◽  
Population Density ◽  
Cell Population ◽  
Tritiated Thymidine ◽  
Tetrahymena Pyriformis ◽  
High Cell ◽  
Ciliated Protozoan ◽  
G2 Phase ◽  
Cell Densities ◽  
Two Peaks

The ciliated protozoan, Tetrahymena pyriformis strain GL-C, has been used to study the effect of cell population density during starvation on the synchrony obtained after refeeding and on the number of cells arrested in G2 phase of the cell cycle. At high cell densities two peaks of division indices were observed after refeeding while only one was observed at low cell densities. Cell division began earlier in cultures starved at high cell densities. Most importantly, the proportion of cells in G2 was considerably higher in populations starved at high cell densities. When tritiated thymidine was present during the refeeding period, radioautographs of cell samples at different times showed that the first cells to exhibit division furrows contained unlabeled nuclei. The first peak in the division index after refeeding was observed only at higher cell densities and is attributed to the cells arrested in G2. These results suggest that Tetrahymena is an excellent organism to study the concept of resting stages in the cell cycle and their control.

scholarly journals Cyclic AMP metabolism in the cell cycle of tetrahymena pyriformis

FEBS Letters ◽  
1976 ◽  
Vol 65 (2) ◽  
pp. 152-154 ◽  
Author(s):  
J.R. Dickinson ◽  
M.G. Graves ◽  
B.E.P. Swoboda
Keyword(s):  
Cell Cycle ◽  
Cyclic Amp ◽  
Tetrahymena Pyriformis

scholarly journals A review of the life cycles and life-history adaptations of pelagic tunicates to environmental conditions

2011 ◽  
Vol 69 (3) ◽  
pp. 358-369 ◽  
Author(s):  
Don Deibel ◽  
Ben Lowen
Keyword(s):  
Life History ◽  
Environmental Conditions ◽  
Generation Time ◽  
Egg Production ◽  
Food Concentration ◽  
Life Cycles ◽  
Population Doubling ◽  
Event Scale ◽  
Generation Times ◽  
Doubling Times

Abstract Deibel, D., and Lowen, B. 2012. A review of the life cycles and life-history adaptations of pelagic tunicates to environmental conditions. – ICES Journal of Marine Science, 69: 358–369. Phylogeny, life cycles, and life-history adaptations of pelagic tunicates to temperature and food concentration are reviewed. Using literature data on lifetime egg production and generation time of appendicularians, salps, and doliolids, rmax, the maximum rate of lifetime reproductive fitness, is calculated as a common metric of adaptation to environmental conditions. The rmax values are high for all three groups, ranging from ∼0.1 to 1.9 d−1, so population doubling times range from ∼8 h to 1 week. These high values of rmax are attributable primarily to short generation times, ranging from 2 to 50 d. Clearly, pelagic tunicates are adapted to event-scale (i.e. days to weeks) rather than seasonal-scale changes in environmental conditions. Although they are not closely related phylogenetically, all three groups have a unique life-history adaptation promoting high lifetime fitness. Appendicularians have late oocyte selection, salps are viviparous, and doliolids possess a polymorphic asexual phase. There has been little research on hermaphroditic appendicularians, on large oceanic salps, and on doliolids generally. Research is needed on factors regulating generation time, on the heritability of life-history traits, and on age- and size-specific rates of mortality.

scholarly journals Hibernation is associated with increased survival and the evolution of slow life histories among mammals

2011 ◽  
Vol 278 (1723) ◽  
pp. 3355-3363 ◽  
Author(s):  
Christopher Turbill ◽  
Claudia Bieber ◽  
Thomas Ruf
Keyword(s):  
Life Histories ◽  
Survival Rates ◽  
Diverse Range ◽  
Annual Survival ◽  
Active Season ◽  
Evolutionary Theories ◽  
Generation Times ◽  
Evolution Of Life ◽  
Reproductive Rates ◽  
Similar Survival

Survival probability is predicted to underlie the evolution of life histories along a slow–fast continuum. Hibernation allows a diverse range of small mammals to exhibit seasonal dormancy, which might increase survival and consequently be associated with relatively slow life histories. We used phylogenetically informed GLS models to test for an effect of hibernation on seasonal and annual survival, and on key attributes of life histories among mammals. Monthly survival was in most cases higher during hibernation compared with the active season, probably because inactivity minimizes predation. Hibernators also have approximately 15 per cent higher annual survival than similar sized non-hibernating species. As predicted, we found an effect of hibernation on the relationships between life history attributes and body mass: small hibernating mammals generally have longer maximum life spans (50% greater for a 50 g species), reproduce at slower rates, mature at older ages and have longer generation times compared with similar-sized non-hibernators. In accordance with evolutionary theories, however, hibernating species do not have longer life spans than non-hibernators with similar survival rates, nor do they have lower reproductive rates than non-hibernators with similar maximum life spans. Thus, our combined results suggest that (i) hibernation is associated with high rates of overwinter and annual survival, and (ii) an increase in survival in hibernating species is linked with the coevolution of traits indicative of relatively slow life histories.

An autoradiographical study of amino acid and nucleoside incorporation during the cell cycle of Amoeba proteus

1981 ◽  
Vol 51 (1) ◽  
pp. 219-228
Author(s):  
K.I. Mills ◽  
L.G. Bell
Keyword(s):  
Cell Cycle ◽  
Amino Acids ◽  
Amino Acid ◽  
Rna Synthesis ◽  
Thymidine Incorporation ◽  
Tritiated Thymidine ◽  
Amoeba Proteus ◽  
Macromolecular Synthesis ◽  
Future Studies ◽  
Specific Proteins

The incorporation of tritiated thymidine, uridine and leucine, into the acid-precipitable material of DNA. RNA and proteins, respectively, was studied by autoradiography throughout the cell cycle of Amoeba proteus. DNA synthesis occupied the first 17 h of the cycle (57 h long) and 2 peaks between 0.5 and 9.13 h accounted for the majority of the thymidine incorporation. RNA synthesis was represented by a series of peak uridine grain counts, the 3 major peaks occurring at 10, 26–27 and 47–48 h. The incorporation of leucine also followed a pattern of peaks and dips, the main peaks occurring 1–2 h after the major increases in uridine incorporation. The fraction of label present over the nucleus decreased during the cell cycle, and this was probably due to a lowered incorporation of the leucine label by proteins synthesized in the cytoplasm and destined to become nuclear proteins. The incorporation patterns of 6 amino acids (arginine, aspartic acid, leucine, lysine, serine and valine) were studied individually during 3 periods of the cell cycle: 0-10 h (S phase); 20–30 h (early G2); and 40–50 h (mid-late G2). Variations in the intensity and timings of the incorporation maxima of the amino acids were observed, although the timings of increased grain counts of some of the amino acids frequently coincided. “Unique” incorporation peaks (i.e. only observed in one of the amino acids studied) possibly indicate the synthesis of phase-specific proteins. The amino acid and nucleoside incorporation profiles presented in this paper will enable the results obtained from future studies on amoebae to be related to the macromolecular synthesis patterns.

scholarly journals The May threshold and life-history allometry

2010 ◽  
Vol 6 (6) ◽  
pp. 850-853 ◽  
Author(s):  
Lev R. Ginzburg ◽  
Oskar Burger ◽  
John Damuth
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Density Dependence ◽  
Reproductive Rate ◽  
Average Lifetime ◽  
A Value ◽  
Generation Times ◽  
Physiologically Based ◽  
Reproductive Rates ◽  
Similar Density

One of Robert May's classic results was finding that population dynamics become chaotic when the average lifetime rate of reproduction exceeds a certain value. Populations whose reproductive rates exceed this May threshold probably become extinct. The May threshold in each case depends upon the shape of the density-dependence curve, which differs among models of population growth. However, species of different sizes and generation times that share a roughly similar density-dependence curve will also share a similar May threshold. Here, we argue that this fact predicts a striking allometric regularity among animal taxa: lifetime reproductive rate should be roughly independent of body size. Such independence has been observed in diverse taxa, but has usually been ascribed to a fortuitous combination of physiologically based life-history allometries. We suggest, instead, that the ecological elimination of unstable populations within groups that share a value of the May threshold is a likely cause of this allometry.

scholarly journals THE SYNTHESIS OF MICROTUBULE AND OTHER PROTEINS OF THE ORAL APPARATUS IN TETRAHYMENA PYRIFORMIS

1971 ◽  
Vol 50 (3) ◽  
pp. 709-720 ◽  
Author(s):  
John Rannestad ◽  
Norman E. Williams
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Acetic Acid ◽  
Tetrahymena Pyriformis ◽  
Basal Bodies

Several proteins, including microtubule proteins, have been isolated from the oral apparatus of the ciliate Tetrahymena. The synthesis of these proteins has been studied in relation to formation of this organelle system by the cell. Electron microscopy has shown that the isolated oral apparatus consists primarily of basal bodies, pellicular membranes, and a system of subpellicular microtubules and filaments. Cilia were removed during the isolation; therefore none of the proteins studied was from these structures. Evidence was obtained from the study of total oral apparatus protein which indicates that at least some of the proteins involved in formation of this organelle system may be synthesized and stored in the cytoplasm for use over long periods. This pattern of regulation was found for three individual proteins isolated from the oral apparatus fraction after extraction with a phenol-acetic acid solvent. A different pattern of regulation was found for microtubule proteins isolated from the oral apparatus of Tetrahymena. The data suggest that microtubule proteins, at least in logarithmically growing cells, are not stored in a cytoplasmic pool but are synthesized in the same cell cycle in which they are assembled into oral structures.

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