scholarly journals TIMING OF DNA SYNTHESIS IN THE MITOTIC CYCLE IN VITRO

1961 ◽  
Vol 9 (3) ◽  
pp. 509-518 ◽  
Author(s):  
Jesse E. Sisken ◽  
Riojun Kinosita
Keyword(s):  
Dna Synthesis ◽  
Generation Time ◽  
Mitotic Cycle ◽  
Tritiated Thymidine ◽  
Lung Cells ◽  
Human Amnion ◽  
Cells In Culture ◽  
Single Colony ◽  
Distribution Of Values

A study was made of the timing of DNA synthesis in the mitotic cycle under conditions where the average mitotic cycle of populations of human amnion and kitten lung cells in culture was variable. Three types of experiments were performed: (a) Autoradiographs were made of incorporated tritiated thymidine in cells whose mitotic histories were recorded microcinematographically allowing the measurement of telophase + G1 along with the total length of the mitotic cycle. (b) Measurement of the G2 + prophase part of the mitotic cycle was performed under various conditions by exposing cells to tritiated thymidine and observing the increase in labeled metaphases plus anaphases as a function of time. (c) The effect of a change in pH on parts of the mitotic cycle was tested by continuously photographing a single colony of cells first at pH 7.8 and then at pH 7.1. All of our data point to the same conclusion; namely, that within a population of cells with a given generation time, the length of each of the measurable parts of the mitotic cycle has a particular distribution of values and that, when there is a change in the generation time, under our conditions only the T + G1 distribution changes.

scholarly journals INTRAPOPULATION KINETICS OF THE MITOTIC CYCLE

1965 ◽  
Vol 25 (2) ◽  
pp. 179-189 ◽  
Author(s):  
Jesse E. Sisken ◽  
Luciano Morasca
Keyword(s):  
Generation Time ◽  
Mitotic Cycle ◽  
Tritiated Thymidine ◽  
Age Distribution ◽  
Time Lapse ◽  
Human Amnion ◽  
Generation Times ◽  
The Right ◽  
Kinetics Of ◽  
Autoradiographic Detection

Data obtained with time lapse cinemicrographic techniques showed that the distribution of generation times for exponentially proliferating human amnion cells in culture is skewed to the right and that reciprocals of generation times appear normally distributed. As shown for bacteria, the true age distribution is much broader than theoretical distributions which fail to take into account the dispersion of generation times. By means of the technique utilizing autoradiographic detection of tritiated thymidine in cells whose mitotic histories were recorded by time lapse cinemicrography, it was shown that the G1 distribution is similar to the generation time distribution but is more variable. In our experiments, the G2 + prophase distribution resembled the generation time and G1 distributions. The data suggested two possibilities for S: either it is relatively constant, or it is inversely related to the lengths of G1 and G2 + prophase. Since G1 is more variable than the total cycle, and G2 + prophase more variable than the computed sum of S + G2 + prophase + metaphase, it was concluded that the relationships between parts of the cycle are non-random and that compensating mechanisms apparently help regulate the lengths of successive parts of the mitotic cycle in individual cells.

Damage by Dichlorvos of Human Lymphocyte DNA

1980 ◽  
Vol 66 (4) ◽  
pp. 425-430 ◽  
Author(s):  
Paolo Perocco ◽  
Angela Fini
Keyword(s):  
Dna Synthesis ◽  
Human Lymphocyte ◽  
Tritiated Thymidine ◽  
Human Lymphocytes ◽  
Ultraviolet Rays ◽  
Thymidine Uptake ◽  
Short Term ◽  
In Vitro System ◽  
Tritiated Thymidine Uptake

The action of dichlorvos (2.2-dichlorovinyldimethyl phosphate) was studied with a short-term in vitro system which utilizes human lymphocytes. The parameters studied were the action exerted by the pesticide on scheduled (semiconservative) and unscheduled (reparative) DNA synthesis measured as tritiated thymidine uptake. The results obtained show that dichlorvos affects semiconservative DNA synthesis, damages human lymphocyte DNA inducing low reparative synthesis, and interferes with DNA repair processes after damage exerted by ultraviolet rays.

scholarly journals The effect of chemotherapy on the kinetics and proliferative capacity of normal and tumorous tissues in vivo

Blood ◽  
1975 ◽  
Vol 45 (1) ◽  
pp. 107-118 ◽  
Author(s):  
SH Rosenoff ◽  
JM Bull ◽  
RC Young
Keyword(s):  
Bone Marrow ◽  
Dna Synthesis ◽  
Colony Formation ◽  
Antitumor Agents ◽  
Tritiated Thymidine ◽  
Chemotherapeutic Agents ◽  
Proliferative Capacity

Abstract The proliferative state of a given tissue is a major determinant of its sensitivity to both phase-specific and cycle-specific chemotherapeutic agents. To study the extent of injury induced by antitumor agents to normal and tumorous tissues, a technique for following DNA synthesis as reflected in the incorporation of tritiated thymidine (3H-TdR) into DNA was compared to the conventional radioautographic technique of the labeling index (LI) and to the functional kinetic technique of granulocyte colony formation in vitro. Alterations in DNA synthesis induced by a single dose of cyclophosphamide in normal and tumorous tissues in vivo paralleled in many respects the changes seen when the more time-consuming techniques of the LI or granulocyte colony formation were employed. However, the recovery of granulocyte colony formation after cyclophosphamide therapy laged behind the recovery of DNA synthesis in the bone marrow, obscuring a kinetic event of potential therapeutic significance. The determination of DNA synthesis simultaneously in normal and tumorous tissues in vivo was easy to perform and supplied therapeutically pertinent results comparatively quickly.

270. Androgens augment the mitogenic effects of oocyte-secreted factors and growth differentiation factor 9 on porcine granulosa cells

2005 ◽  
Vol 17 (9) ◽  
pp. 111
Author(s):  
T. E. Hickey ◽  
D. L. Marrocco ◽  
F. Amato ◽  
L. J. Ritter ◽  
R. J. Norman ◽  
...  
Keyword(s):  
Dna Synthesis ◽  
Tritiated Thymidine ◽  
Paracrine Signalling ◽  
Secreted Factors ◽  
Differentiation Factor ◽  
Porcine Granulosa Cells ◽  
Growth Differentiation Factor 9 ◽  
Growth Promoting

Androgens, acting directly through the androgen receptor (AR), are thought to promote granulosa cell (GC) growth in vivo, but generally inhibit growth and promote GC differentiation in vitro. We hypothesised that the growth-promoting action of androgens on GC requires paracrine signalling from the oocyte. To test this hypothesis, we cultured mural GC from small antral (1–3mm) pre-pubertal pig follicles in the presence or absence of denuded oocytes (DO) from the same follicles to examine whether mitogenic responses, determined by uptake of tritiated thymidine, to combinations of FSH, insulin like growth factor 1 (IGF1) and dihydrotestosterone (DHT; 500 nM), were influenced by oocyte-secreted factors (OSFs). To further explore the identity of such factors, we performed the same experiments, substituting recombinant mouse growth differentiation factor 9 (GDF9), a known OSF, for the DO. Alone, DHT induced a small (<2-fold), but consistent increase in IGF1-stimulated DNA synthesis. OSFs stimulated DNA synthesis in all experimental combinations, most significantly in the presence of IGF1 (P < 0.0001), and DHT enhanced (P<0.05) the stimulatory effect of OSFs in all instances. Like OSFs, GDF9 substantially increased IGF1-stimulated DNA synthesis (P < 0.0001), and again, DHT enhanced (P > 0.01) this effect. In further experiments, two AR agonists, testosterone (10-1000nM) and DHT (5–500 nM), dose-dependently augmented the mitogenic effect of OSFs or GDF9 in the presence of IGF1. Only the highest doses of androgen had an independent stimulatory effect; lower doses required the presence of an OSF(s). Antiandrogen (hydroxyflutamide) treatment, used to block AR activity, antagonized the androgen X GDF9 interaction. In conclusion, androgens, via activation of the AR, stimulate porcine GC proliferation in vitro by potentiating the growth-promoting effects of oocytes or GDF9. These signalling pathway interactions are likely to be important regulators of folliculogenesis in vivo and may cause the excess follicle growth that is observed in androgen-treated female animals.

scholarly journals MACROMOLECULAR SYNTHESES RELATED TO THE REPRODUCTIVE CYST OF TETRAHYMENA PATULA

1973 ◽  
Vol 59 (3) ◽  
pp. 615-623 ◽  
Author(s):  
P. R. Gabe ◽  
L. E. de Bault
Keyword(s):  
Protein Synthesis ◽  
Dna Synthesis ◽  
Generation Time ◽  
Rna Synthesis ◽  
Culture Medium ◽  
Tritiated Thymidine ◽  
Growth Cycle ◽  
The Third ◽  
Rna And Protein Synthesis ◽  
The Mean

Macromolecular syntheses in encysted Tetrahymena patula were studied using Feulgen fluorescence cytophotometry, autoradiography, and inhibitors of RNA and protein synthesis. Cycloheximide significantly depressed protein synthesis and D-actinomycin effectively blocked RNA synthesis. Under these conditions, the cells within the cyst were unable to divide. Both cytophotometric measurements and autoradiographic data with tritiated thymidine show that DNA synthesis does not occur during the encystment divisions. Excysted cells placed in nutrient broth medium showed a prolonged generation time after the first cell growth cycle, and by the third generation the mean DNA content per cell was almost triple that of starved excysted cells. These findings indicate that (a) the encystment divisions require RNA and protein synthesis, which are apparently effected through turnover, (b) the encystment division cycles occur in the absence of DNA synthesis, and (c) excysted cells placed in culture medium may go through more than one DNA replication per cell cycle.

In vitro activation of mouse eggs

Development ◽  
1974 ◽  
Vol 31 (2) ◽  
pp. 497-512
Author(s):  
C. F. Graham ◽  
Z. A. Deussen
Keyword(s):  
Dna Synthesis ◽  
Culture Medium ◽  
Tritiated Thymidine ◽  
Polar Body ◽  
Similar Time ◽  
Body Formation ◽  
Polar Body Formation ◽  
Second Polar Body ◽  
Mouse Eggs

Unfertilized mouse eggs were activated in vitro with hyaluronidase. Subsequently they were exposed to culture medium at different osmolarities. In full strength White's culture medium they tended to form one pronucleus and a second polar body. The majority of these eggs were haploid. In 4/5 and 3/5 dilutions of this medium, the second polar body formation was suppressed and eggs tended to form with one or two pronuclei. Those with one pronucleus were diploid and those with two pronuclei could either form a diploid or form a haploid mosaic. Old eggs tended to immediately cleave and form haploid mosaics. DNA synthesis was studied in activated eggs using tritiated thymidine and autoradiography. DNA synthesis occurred at a similar time in fertilized and activated eggs.

Initiation of DNA synthesis by kinetin and experimental factors in tobacco pith tissues in vitro

1971 ◽  
Vol 49 (9) ◽  
pp. 1541-1549 ◽  
Author(s):  
Antoine Simard
Keyword(s):  
Dna Synthesis ◽  
Liquid Scintillation ◽  
Nuclear Dna ◽  
Tritiated Thymidine ◽  
Scintillation Counting ◽  
Basic Medium ◽  
Control Medium ◽  
Cell Nuclei ◽  
Counting Methods

Since previous investigations had suggested that kinetin, like auxin, may initiate DNA synthesis in tobacco pith cells, a study was undertaken to learn whether the observed incorporation of tritiated thymidine into nuclear DNA in the presence of kinetin could be explained by different experimental factors.Pith tissues were isolated and allowed to rest a few days after excision and they were then placed on White's basic medium or on that medium supplemented with either one or both of the growth regulators in the presence of tritiated thymidine.The results of those studies, obtained by radioautographic and liquid scintillation counting methods, showed no statistically significant differences between pith tissues kept on the control medium and those on kinetin-containing medium. Similar tissues placed on an auxin or auxin- and kinetin-containing medium showed, as expected, a significant incorporation of tritiated thymidine into the DNA of pith cell nuclei.

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