Studies on the Autonomy of Pellicular DNA in Paramecium

1969 ◽  
Vol 5 (2) ◽  
pp. 365-372
Author(s):  
JOAN SMITH-SONNEBORN ◽  
W. PLAUT
Keyword(s):  
Dna Synthesis ◽  
Tritiated Thymidine ◽  
Autoradiographic Study ◽  
Sensitive Material ◽  
Selective Labelling ◽  
The Relationship

This autoradiographic study was designed to elucidate the relationship between the macronucleus and pellicular DNA in Paramecium. The capacity of the cell to synthesize pellicular DNA in the absence of the macronucleus was established by demonstrating the incorporation of tritiated thymidine into DNase-sensitive material in the pellicles of amacronucleate cells. Moreover, using a technique which leads to selective labelling of the macronucleus in normal paramecia, we have looked for evidence of transfer of labelled DNA from the macronucleus to the pellicle with time. Finding none, we conclude that labelled pellicular DNA is not of macronuclear origin, and that labelled pellicular DNA synthesis is not directly dependent on the presence of the macronucleus.

The development of the tectum in Xenopus laevis: an autoradiographic study

Development ◽  
1972 ◽  
Vol 28 (1) ◽  
pp. 87-115
Author(s):  
K. Straznicky ◽  
R. M. Gaze
Keyword(s):  
Xenopus Laevis ◽  
Dna Synthesis ◽  
Optic Tectum ◽  
Tritiated Thymidine ◽  
Dorsal Surface ◽  
Autoradiographic Study ◽  
Cell Type ◽  
Pole Cells ◽  
Serial Addition ◽  
The Times

The development of the optic tectum in Xenopus laevis has been studied by the use of autoradiography with tritiated thymidine. The first part of the adult tectum to form is the rostroventral pole; cells in this position undergo their final DNA synthesis between stages 35 and 45 or shortly thereafter. Next, the cells comprising the ventrolateral border of the tectum form. These cells undergo their final DNA synthesis at or shortly after stage 45. Finally the cells comprising the dorsal surface of the adult tectum form, mainly between stages 50–55. This part of the tectum originates from the serial addition of strips of cells medially, which displace the pre-existing tissue laterally and rostrally. The formation of the tectum is virtually complete by stage 58. The tectum in Xenopus thus forms in topographical order from rostroventral to caudo-medial. The distribution of labelled cells, several stages after the time of injection of isotope, indicates that, at any one time, a segment of tectum is forming which runs normal to the tectal surface and includes all layers from the ventricular layer out to the surface. In Xenopus, therefore, the times of origin of tectal cells appear to be related not to cell type or tectal layer but to the topographical position of the cells across the surface of the tectum.

scholarly journals AUTORADIOGRAPHIC STUDY OF DNA SYNTHESIS AND THE CELL CYCLE IN SPERMATOGONIA AND SPERMATOCYTES OF MOUSE TESTIS USING TRITIATED THYMIDINE

1962 ◽  
Vol 14 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Valerio Monesi
Keyword(s):  
Dna Synthesis ◽  
Time Course ◽  
Average Duration ◽  
Tritiated Thymidine ◽  
Periodic Acid ◽  
Autoradiographic Study ◽  
Type B ◽  
Average Life ◽  
Periodic Acid Schiff ◽  
Average Life Span

Mice were injected intraperitoneally with 15 µc of H3-thymidine. The time course of the labeling in spermatogonia and spermatocytes was studied by using autoradiography on 5 µ sections stained by the periodic acid-Schiff method and hematoxylin over a period of 57 hours after injection. Four generations of type A (called AI, AII, AIII, and AIV), one of intermediate, and one of type B spermatogonia occur in one cycle of the seminiferous epithelium. The average life span is about the same in all spermatogonia, i.e., about 27 to 30.5 hours. The average pre-DNA synthetic time, including the mitotic stages from metaphase through telophase and the portion of interphase preceding DNA synthesis, is also not very different, ranging between 7.5 and 10.5 hours. A remarkable difference exists, however, in the duration of DNA synthesis and of the post-DNA synthetic period. The average DNA synthetic time is very long and is highly variable in type B (14.5 hours), a little shorter and less variable in intermediate (12.5 hours) and AIV (13 hours) spermatogonia, and much shorter and very constant in AIII (8 hours), AII and AI (7 to 7.5 hours) spermatogonia. Conversely, the average post-DNA synthetic time, corresponding essentially to the duration of the prophase, is short and very constant in type B (4.5 hours), longer and variable in intermediate (6 hours) and AIV (8 hours) spermatogonia, and much longer and much more variable in AIII (11 hours), AII and AI (14 hours) spermatogonia. The premeiotic synthesis of DNA takes place in primary spermatocytes during the resting phase and terminates just before the visible onset of the meiotic prophase. Its average duration is 14 hours. No further synthesis of DNA takes place in later stages of spermatogenesis.

A STUDY OF BLASTOCYSTS DURING DELAY AND SUBSEQUENT IMPLANTATION IN LACTATING MICE

1968 ◽  
Vol 42 (3) ◽  
pp. 453-463 ◽  
Author(s):  
ANNE McLAREN
Keyword(s):  
Dna Synthesis ◽  
Thymidine Incorporation ◽  
Tritiated Thymidine ◽  
Uterine Horn ◽  
Uterine Epithelium ◽  
Serial Sections ◽  
Uterine Lumen ◽  
Fresh State

SUMMARY Blastocysts were studied on the 5th and 8th day of pregnancy in lactating mice, in the fresh state, flushed from the uterus, in squash preparations and in serial sections. At the earlier period some mitosis was observed. Tritiated thymidine incorporation studies gave some evidence of DNA synthesis on the 5th and 6th days of pregnancy. By the 8th day the blastocysts were longer, contained more cells, and mitosis had ceased. They were located at the anti-mesometrial end of the uterine lumen, closely apposed to the uterine epithelium, and with their long axes parallel to the long axis of the uterine horn. Implantation could be induced, either by the removal of the litter, or by the injection of an appropriate dose of oestrogen on the 5th or 7th (but not the 4th) day of pregnancy. Both treatments were followed by the appearance of W-bodies in the neighbourhood of the blastocysts, the disappearance of the shed zonae, and the appearance of Pontamine Blue reactivity, oedema of the uterine stroma and formation of the primary decidual zone, in that order.

scholarly journals CYTOPLASMIC DNA SYNTHESIS IN AMOEBA PROTEUS

1962 ◽  
Vol 15 (3) ◽  
pp. 525-534 ◽  
Author(s):  
M. Rabinovitch ◽  
W. Plaut
Keyword(s):  
Dna Synthesis ◽  
Tritiated Thymidine ◽  
Amoeba Proteus ◽  
Living Cells ◽  
Large Numbers ◽  
Cytoplasmic Dna ◽  
Basic Dyes ◽  
Nuclease Digestion ◽  
High Degree ◽  
Very High

The incorporation of tritiated thymidine in Amoeba proteus was reinvestigated in order to see if it could be associated with microscopically detectable structures. Staining experiments with basic dyes, including the fluorochrome acridine orange, revealed the presence of large numbers of 0.3 to 0.5 µ particles in the cytoplasm of all cells studied. The effect of nuclease digestion on the dye affinity of the particles suggests that they contain DNA as well as RNA. Centrifugation of living cells at 10,000 g leads to the sedimentation of the particles in the centrifugal third of the ameba near the nucleus. Analysis of centrifuged cells which had been incubated with H3-thymidine showed a very high degree of correlation between the location of the nucleic acid-containing granules and that of acid-insoluble, deoxyribonuclease-sensitive labeled molecules and leads to the conclusion that cytoplasmic DNA synthesis in Amoeba proteus occurs in association with these particles.

Postnatal neurogenesis in the olfactory bulbs of a lizard. A tritiated thymidine autoradiographic study

1989 ◽  
Vol 98 (3) ◽  
pp. 247-252 ◽  
Author(s):  
J.M. Garcia-Verdugo ◽  
S. Llahi ◽  
I. Ferrer ◽  
C. Lopez-Garcia
Keyword(s):  
Tritiated Thymidine ◽  
Autoradiographic Study ◽  
Postnatal Neurogenesis ◽  
Olfactory Bulbs

Autoradiographic study of DNA-synthesis in the regenerating liver of the mouse

1966 ◽  
Vol 44 (2-3) ◽  
pp. 676-678 ◽  
Author(s):  
E.G. Bade ◽  
I.L. Sadnik ◽  
C. Pilgrim ◽  
W. Maurer
Keyword(s):  
Dna Synthesis ◽  
Autoradiographic Study ◽  
Regenerating Liver

scholarly journals Arginine deprivation in KB cells: I. Effect on cell cycle progress

1977 ◽  
Vol 75 (3) ◽  
pp. 881-888 ◽  
Author(s):  
AS Weissfeld ◽  
H Rouse
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Tritiated Thymidine ◽  
Experimental Period ◽  
Cell Multiplication ◽  
Starvation Period ◽  
Kb Cells ◽  
Insoluble Material ◽  
Cell Cycle Inhibition ◽  
Cellular Dna

When exponentially growing KB cells were deprived of arginine, cell multiplication ceased after 12 h but viability was maintained throughout the experimental period (42-48 h). Although tritiated thymidine ([(3)H]TdR) incorporation into acid-insoluble material declined to 5 percent of the initial rate, the fraction of cells engaged in DNA synthesis, determined by autoradiography, remained constant throughout the starvation period and approximately equal to the synthesizing fraction in exponentially growing controls (40 percent). Continous [(3)H]TdR-labeling indicated that 80 percent of the arginine-starved cells incorporated (3)H at some time during a 48-h deprivation period. Thus, some cells ceased DNA synthesis, whereas some initially nonsynthesizing cells initiated DNA synthesis during starvation. Flow microfluorometric profiles of distribution of cellular DNA contents at the end of the starvation period indicated that essentially no cells had a 4c or G2 complement. If arginine was restored after 30 h of starvation, cultures resumed active, largely asynchronous division after a 16-h lag. Autoradiographs of metaphase figures from cultures continuously labeled with [(3)H]TdR after restoration indicated that all cells in the culture underwent DNA synthesis before dividing. It was concluded that the majority of cells in arginine-starved cultures are arrested in neither a normal G1 nor G2. It is proposed that for an exponential culture, i.e. from most positions in the cell cycle, inhibition of cell growth after arginine with withdrawal centers on the ability of cells to complete replication of their DNA.

HYPERTROPHY AND HYPERPLASIA IN THE MOUSE UTERUS AFTER OESTROGEN TREATMENT: AN AUTORADIOGRAPHIC STUDY

1973 ◽  
Vol 56 (1) ◽  
pp. 133-NP ◽  
Author(s):  
L. MARTIN ◽  
C. A. FINN ◽  
GAIL TRINDER
Keyword(s):  
Cell Death ◽  
Dna Synthesis ◽  
Proliferative Response ◽  
Autoradiographic Study ◽  
Luminal Epithelium ◽  
Uterine Tissue ◽  
Mouse Uterus ◽  
Oestrogen Treatment ◽  
Ovariectomized Mice

SUMMARY The uteri of untreated ovariectomized mice consisted almost entirely of myometrium and connective tissue stroma. After oestrogenic stimulation these tissues underwent marked hypertrophy, but showed little proliferation. The luminal epithelium underwent marked hyperplasia, with most cells dividing twice to quadruple cell numbers by 35–40 h, when they made up 10–12% of the uterine tissue volume and 20% of the total uterine cell population. The proliferative response was rapid, highly synchronized and short-lived. The number of cells incorporating [3H]thymidine first increased 8·5 h after oestradiol-17β and by 13–16 h 60–70% were engaged in DNA synthesis. Up to 21 h cell-death was minimal. From 21 h onwards the proliferation rate declined and the rate of cell death increased. A second injection of oestrogen prevented the rise in death rate and produced a second smaller burst of DNA synthesis. Cells in DNA synthesis or mitosis were insensitive to oestrogen. A smaller proliferative response occurred in the glands: only 25% of cells entered DNA synthesis after the first injection of oestradiol and none after the second. Gland cells appeared to die in situ and there was no evidence that they migrated into the luminal epithelium.

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