scholarly journals THE RELATIONSHIP BETWEEN DEOXYRIBONUCLEIC ACID REPLICATION AND CELL DIVISION IN HEAT-SYNCHRONIZED TETRAHYMENA

1970 ◽  
Vol 46 (3) ◽  
pp. 533-543 ◽  
Author(s):  
William R. Jeffery ◽  
Kenneth D. Stuart ◽  
Joseph Frankel
Keyword(s):  
Cell Division ◽  
Heat Shock ◽  
Dna Synthesis ◽  
Deoxyribonucleic Acid ◽  
Heat Shock Treatment ◽  
Heat Shocks ◽  
Prolonged Heat ◽  
S Period ◽  
C 50 ◽  
The Relationship

The effect of supraoptimal temperature on macronuclear DNA synthesis in Tetrahymena was studied by radioautography during prolonged heat and heat-shock synchronization treatments. Prolonged heat treatments (34°C) delayed the initiation of S, but did not appreciably delay DNA synthesis in progress. Return to optimal temperature (28°C) 50 or 100 min later resulted in initiation of S, in delayed cells, at a rate greater than in controls. During the synchronization treatment, most cells were unable to enter S during a heat shock, but initiated S with a slight delay during the following intershock period. These cells were not appreciably delayed in completion of S by subsequent heat shocks. Supraoptimal temperature appears to affect the DNA synthetic cycle near the G1 to S transition. Cells subjected to the heat-shock treatment in early G1 all participated in one S period, and many underwent a succession of two S periods. DNA synthesis occurred in about 50% of the cells between EST and the first synchronous division, with the likelihood of DNA synthesis becoming greater the longer the interval between these two events. In some cells no detectable DNA synthesis occurred between EST and the second synchronous division. It was concluded that a precise temporal alternation of DNA replication and cell division is not obligatory in Tetrahymena.

scholarly journals EVIDENCE FOR A TEMPORAL INCOMPATIBILITY BETWEEN DNA REPLICATION AND DIVISION DURING THE CELL CYCLE OF TETRAHYMENA

1972 ◽  
Vol 53 (3) ◽  
pp. 624-634 ◽  
Author(s):  
William R. Jeffery
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Replication ◽  
Heat Shock ◽  
Dna Synthesis ◽  
Shock Treatment ◽  
Coupling Mechanism ◽  
Complete Suppression ◽  
Heat Shock Treatment ◽  
S Period

The mechanism of coordination between DNA replication and cell division was studied in Tetrahymena pyriformis GL-C by manipulation of the timing of these events with heat shocks and inhibition of DNA synthesis. Preliminary experiments showed that the inhibitor combination methotrexate and uridine (M + U) was an effective inhibitor of DNA synthesis. Inhibition of the progression of DNA synthesis with M + U in exponentially growing cells, in which one S period usually occurs between two successive divisions, or in heat-shocked cells, when successive S periods are known to occur between divisions, resulted in the complete suppression of the following division. In further experiments in which the division activities were reassociated with the DNA synthetic cycle by premature termination of the heat-shock treatment, it was shown that (a) the completion of one S period during the treatment was sufficient for cell division, (b) the beginning of division events suppressed the initiation of further S periods, and (c) if further S periods were initiated while the heat-shock treatment was continued, division preparations could not begin until the necessary portion of the S period was completed, even though DNA had previously been duplicated. It was concluded that a temporal incompatibility exists between DNA synthesis and division which may reflect a coupling mechanism which insures their coordination during the normal cell cycle.

scholarly journals ANALYSIS OF THE SCHEDULE OF DNA REPLICATION IN HEAT-SYNCHRONIZED TETRAHYMENA

1973 ◽  
Vol 59 (1) ◽  
pp. 1-11 ◽  
Author(s):  
William R. Jeffery ◽  
Joseph Frankel ◽  
Lawrence E. de Bault ◽  
Leslie M. Jenkins
Keyword(s):  
Cell Cycle ◽  
High Temperature ◽  
Dna Replication ◽  
Heat Shock ◽  
Dna Synthesis ◽  
Shock Treatment ◽  
Heat Shock Treatment ◽  
Dividing Cells ◽  
S Period ◽  
Selection Of

The temporal schedule of DNA replication in heat-synchronized Tetrahymena was studied by autoradiographic and cytofluorometric methods. It was shown that some cells, which were synchronized by selection of individual dividing cells or by temporary thymidine starvation, incorporated [3H]thymidine into macronuclei in a periodic fashion during the heat-shock treatment. It was concluded that supernumerary S periods occurred while cell division was blocked by high temperature. The proportion of cells which initiated supernumerary S periods was found to be dependent on the duration of the heat-shock treatment and on the cell cycle stage when the first heat shock was applied. Cytofluorometric measurements of Feulgen-stained macronuclei during the heat-shock treatment indicated that the DNA complement of these cells was substantially increased and probably duplicated during the course of each S period. Estimates of DNA content also suggested that the rate of DNA synthesis progressively declined during long heat-shock treatments. These results indicate that the mechanism which brings about heat-induced division synchrony is not an interruption of the process of DNA replication. Further experiments were concerned with the regulation of DNA synthesis during the first synchronized division cycle. It was shown that participation in DNA synthesis at this time increased as more cells were able to conclude the terminal S period during the preceding heat-shock treatment. It is suggested that a discrete period of time is necessary after the completion of DNA synthesis before another round of DNA synthesis can be initiated.

Cytofluorimetric analysis of nuclear DNA during meiosis, fertilization and macronuclear development in the ciliate Tetrahymena pyriformis, syngen 1

1975 ◽  
Vol 17 (3) ◽  
pp. 471-493 ◽  
Author(s):  
F.P. Doerder ◽  
L.E. Debault
Keyword(s):  
Cell Division ◽  
Dna Synthesis ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Tetrahymena Pyriformis ◽  
Cell Cycles ◽  
Macronuclear Development ◽  
Sister Chromatids ◽  
Nuclear Development ◽  
S Period

Fluorescence cytophotometry was used to study nuclear DNA content and synthesis patterns during meiosis, fertilization and macronuclear development in the ciliated protozoon, Tetrahymena pyriformis, syngen 1. It was found that cells entered conjugation with a G1 (45C) macronucleus and a G2 (4C) micronucleus. During meiosis the micronucleus was reduced to 4 haploid nuclei, each with a 1C amount of DNA; each meiotic product then replicated to 2C, but only the nucleus next to the attachment membrane in each conjugant divided to form the two 1C gametic nuclei. The gametic nuclei replicated to 2C prior to fertilization; hence there was no S-period in the 4C fertilization nucleus (synkaryon). The first postzygotic division products immediately entered an S-period to become 4C, and at the second postzygotic division, each of the two 4C nuclei in each conjugant divided to form one 2C micronucleus and one 2C macronuclear Anlage. The macronuclear Anlagen began DNA synthesis immediately and were about 8C at the completion of conjugation; the micronuclei did not undergo rapid DNA doubling and measured between 2C and 3C when the conjugants separated. The old macronucleus did not participate in any S-period during conjugation and began to decompose after the second postzygotic division; it contained an average of 24C at the end of conjugation. From this sequence of nuclear divisions a pattern emerges that, unless a general cytoplasmic signal for DNA synthesis is suppressed, DNA synthesis always occurs in micronuclear division products immediately following separation of sister chromatids. Nuclear development continued in the first two cell cycles after conjugation. In exconjugants (the first cycle), macronuclear Anlagen underwent two rounds of DNA synthesis to become 32C and both micronuclei also underwent DNA synthesis. However, prior to the first cell division, one micronucleus and the old macronucleus completely disintegrated, and at the first cell division the remaining 4C micronucleus divided and one macronuclear Anlage was distributed to each resulting caryonide. At the end of the second cell cycle, the dividing macronucleus of each caryonide contained about 128C. These results relate to the question of ploidy of macronuclear subunits. It is argued that the G1 macronucleus contains 22 or 23 diploid subunits, each subunit being a copy of the diploid micronuclear genome. It is suggested that unequal macronuclear division relates to the question of subunit ploidy by playing a role in the phenomenon of macronuclear assortment.

scholarly journals Deoxyribonucleic acid synthesis in mammalian nuclei. Incorporation of deoxyribonucleotides and chain-terminating nucleotide analogues

1971 ◽  
Vol 121 (5) ◽  
pp. 803-809 ◽  
Author(s):  
M. A. Waqar ◽  
L. A. Burgoyne ◽  
M. R. Atkinson
Keyword(s):  
Dna Synthesis ◽  
Deoxyribonucleic Acid ◽  
Acid Synthesis ◽  
Deoxyribonucleic Acid Synthesis ◽  
Dna Chain ◽  
Relationship Of ◽  
The Relationship ◽  
Neighbour Analysis

The properties of a nuclear preparation from rat liver and thymus are described. (1) Nearest-neighbour analysis after incorporation of 32P-labelled nucleotide residues from dATP, dCTP, dGTP, dTTP and arabinofuranosyl analogues of CTP and ATP shows template-dependent DNA synthesis. (2) Where primer termini are limiting, incorporation of arabinofuranosyl analogues of AMP and CMP residues proceeds to a limit indicating that both of these analogues are DNA chain terminators. (3) No large differences have been found between the priming potentialities or the intrinsic DNA polymerase activities of nuclei from resting or regenerating liver and the relationship of this DNA synthesis in vitro to DNA replication or repair in vivo is briefly discussed.

scholarly journals The relationship between the excess-delay phenomenon and temperature-sensitive periods in Tetrahymena thermophila

1980 ◽  
Vol 43 (1) ◽  
pp. 75-91
Author(s):  
J. Frankel ◽  
J. Mohler ◽  
A.K. Frankel
Keyword(s):  
Cell Division ◽  
Transition Point ◽  
Tetrahymena Thermophila ◽  
Characteristic Parameter ◽  
Sensitive Period ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Heat Shocks ◽  
Delay Phenomenon ◽  
The Relationship

Although temperatures of 37.5 and 39 degrees C allow continuous and rapid exponential growth of wild type Tetrahymena thermophila, sudden shifts up to these temperatures can bring about long excess-delays of cell division with accompanying resorption of developing oral primordia. A characteristic parameter of this delay-phenomenon is the physiological transition point, before which delays are maximal and after which they are negligible. When measured at a restrictive temperature that does not induce excess delays (36 degrees C), the end of the temperature-sensitive period of the cell division arrest of mutant cdaA1 precedes the physiological transition point, that of cdaH1 roughly coincides with it, while the entire temperature-sensitive period of cdaC2 comes after the physiological transition point. When cdaA1 cells are exposed to 37.5 degrees C or above, the manifestations of temperature sensitivity are drastically affected: the estimate of the end of the temperature-sensitive period (the execution point) becomes spuriously late, and the characteristic division arrest following heat shocks is not manifested. The differential effects of the higher restrictive temperatures on cdaH1 are most subtle, whereas those on cdaC2 are negligible. We conclude that the excess-delay phenomenon involves a set-back of genemediated processes occurring at specific stages of the cell cycle.

scholarly journals Effect of heat shock on the germination of seeds of the species Acacia senegal L. and Acacia seyal Del. from sub-Saharan Africa (Ethiopia).

2019 ◽  
Vol 28 (2) ◽  
pp. e006
Author(s):  
Celia Herrero ◽  
Amelework Kassa ◽  
Valentín Pando ◽  
Felipe Bravo ◽  
Ricardo Alía
Keyword(s):  
Heat Shock ◽  
Logistic Model ◽  
Sub Saharan Africa ◽  
Arid Zones ◽  
Heat Shock Treatment ◽  
Acacia Senegal ◽  
Heat Shocks ◽  
Sub Saharan ◽  
Acacia Seyal ◽  
Germinated Seeds

Aim of the study: Understanding post-fire germination of tree species in arid and semi-arid zones of sub-Saharan Africa.Area of study: Ethiopian Acacia senegal L. and Acacia seyal Del. forests.Material and methods: Seeds were subjected to heat shocks at combinations of four temperatures (60º, 90º, 120º and 150ºC) and three exposure times (1, 5 and 10 minutes). A control was also included, resulting in a total of thirteen treatments. After the application of the heat shocks, the viability of no germinated seeds was assessed after immersion in a Tetrazolium solution. A mixed and a logistic model were used to analyse the influence of heat shock on germination.Main results: Results showed that germination depended on the species, the heat shock treatment and their interaction. Both species showed similar germination results at temperatures below 90ºC in all exposure times, however, germination in Acacia senegal was statistically higher in most of the heat shocks. On the other hand, germination probability decreased in both species, when the exposure time increased, although with a different behaviour. In 1 minute of time of exposure, the germination probability was higher than 60% in the two species throughout the temperature range. However, at 5 minutes of time and temperature smaller than 90°C, the probability of germination was higher than 70% in A. senegal and 50% in A. seyal. Although germination in both species was impacted by the different heat shocks, non-germinated seeds were viable.Research highlights: This paper showed, according to these results, that heat shock would negatively influence the regeneration of both species, and especially for A. seyal.Key words: germination, Acacia, heat shock, logistic model.

P32 uptake in DNA nucleotides after partial hepatectomy and after unilateral nephrectomy

1961 ◽  
Vol 201 (3) ◽  
pp. 523-525 ◽  
Author(s):  
David P. Simpson
Keyword(s):  
Cell Division ◽  
Dna Synthesis ◽  
Partial Hepatectomy ◽  
Intraperitoneal Injection ◽  
Deoxyribonucleic Acid ◽  
Specific Activity ◽  
Unilateral Nephrectomy ◽  
Data Support ◽  
Organ Specific

Deoxyribonucleic acid (DNA) synthesis as reflected in the specific activity of DNA nucleotides 12 hr after intraperitoneal injection of P32 has been compared after partial hepatectomy and after unilateral nephrectomy. Thirty-six hours after partial hepatectomy, a maximum uptake 11-fold greater than in controls was found. The maximum after unilateral nephrectomy occurred 48 hr after operation and was twofold greater than in controls. Subsequent to these maxima, P32 uptake declined after both operations to a minimum eight days postoperatively which was followed by a second rise on the 9th day. These data support the concept that similar basic mechanisms regulate growth and cell division after the two types of operation. In another experiment, P32 uptake in kidney DNA nucleotides showed no increase after partial hepatectomy; this lends weight to the hypothesis that the mitosis-stimulating substances which appear in the serum after partial hepatectomy and after unilateral nephrectomy are organ specific.

Fish kidney cell line in response to heat shock

1992 ◽  
Vol 50 (1) ◽  
pp. 704-705
Author(s):  
Li-Chu Tung ◽  
Yung-Reui Chen ◽  
Shiu-Nan Chen ◽  
Guang-Hsiung Kuo
Keyword(s):  
Heat Shock ◽  
Cell Line ◽  
Fetal Calf Serum ◽  
Calf Serum ◽  
Uranyl Acetate ◽  
Ultrastructural Changes ◽  
Heat Shock Treatment ◽  
Acanthopagrus Schlegeli ◽  
Cacodylate Buffer ◽  
Fish Kidney

In the present study, the ultrastructural changes of BPK cells, a fibroblast-like cell line, derived from the kidney of juvenile black porgy Acanthopagrus schlegeli, under heat shock treatment are described.The BPK cells were maintained in L-15 medium supplemented with 10% fetal calf serum and 0.15 M NaCl at 28|C2. The heating was carried out in precalibrated water baths. Monolayers of cells, grown on coverslips in parafilm-sealed petri dishes were submerged under water for 30 min at 40|C treatments. Cells were fixed in 2.5% glutaraldehyde in 0.1 M cacodylate buffer supplemented with 6.6% sucrose, postfixed in 1% OsO4 and flat embedded in Spurr’s resin. Silver section were cut parallel to the substratum, stained with uranyl acetate and Reynold’s lead citrate, and examined in a Hitachi H-600 electron microscope at 75 KV.

Heat-induced triploids in Brycon amazonicus: a strategic fish species for aquaculture and conservation

Zygote ◽  
2021 ◽  
pp. 1-5
Author(s):  
Nivaldo Ferreira do Nascimento ◽  
Rafaela Manchin Bertolini ◽  
Lucia Soares Lopez ◽  
Laura Satiko Okada Nakaghi ◽  
Paulo Sérgio Monzani ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Heat Shock ◽  
Early Development ◽  
Fish Species ◽  
Survival Rates ◽  
Shock Treatment ◽  
Hatching Rate ◽  
Heat Shock Treatment ◽  
Control Survival ◽  
Ploidy Status

Summary Triploidization plays an important role in aquaculture and surrogate technologies. In this study, we induced triploidy in the matrinxã fish (Brycon amazonicus) using a heat-shock technique. Embryos at 2 min post fertilization (mpf) were heat shocked at 38°C, 40°C, or 42°C for 2 min. Untreated, intact embryos were used as a control. Survival rates during early development were monitored and ploidy status was confirmed using flow cytometry and nuclear diameter analysis of erythrocytes. The hatching rate reduced with heat-shock treatment, and heat-shock treatments at 42°C resulted in no hatching events. Optimal results were obtained at 40°C with 95% of larvae exhibiting triploidy. Therefore, we report that heat-shock treatments of embryos (2 mpf) at 40°C for 2 min is an effective way to induce triploid individuals in B. amazonicus.

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