X-Ray-Induced Incorporation of Tritiated Thymidine into Deoxyribonucleic Acid of Grasshopper Neuroblast Chromosomes

1963 ◽  
Vol 19 (3) ◽  
pp. 526 ◽  
Author(s):  
Richard A. McGrath
Keyword(s):  
Deoxyribonucleic Acid ◽  
Tritiated Thymidine ◽  
X Ray

Sedimentation coefficient and x-ray scattering of a double-helical model for deoxyribonucleic acid

1976 ◽  
Vol 80 (18) ◽  
pp. 2028-2035 ◽  
Author(s):  
J. Garcia de la Torre ◽  
Arturo Horta
Keyword(s):  
Deoxyribonucleic Acid ◽  
Sedimentation Coefficient ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

INCORPORATION OF RADIOACTIVE PURINE AND PYRIMIDINE BASES AND OF THYMIDINE INTO THE DEOXYRIBONUCLEIC ACID OF SALMON MILTS

1964 ◽  
Vol 42 (1) ◽  
pp. 51-57 ◽  
Author(s):  
H. L. A. Tarr
Keyword(s):  
Orotic Acid ◽  
Deoxyribonucleic Acid ◽  
Tritiated Thymidine ◽  
Experimental Conditions ◽  
Live Fish ◽  
Pyrimidine Bases

C14-labeled adenine, guanine and cytosine, and tritiated thymidine were incorporated into the deoxyribonucleic acid of salmon milts, either by injection into the milts of live fish or into excised milts. The amount incorporated was very small. Under the experimental conditions radioactive nucleosides, deoxyuridine, adenosine 5′-mono- and tri-phosphates, orotic acid, uracil, ribose 1-phosphate, and ribose 5-phosphate were not incorporated. It is suggested that these results may be due to the comparative impermeability of the cells to the various compounds.

EFFECTS OF A GLUCOCORTICOID (DEXAMETHASONE) ON THE EOSINOPHILS OF THE RAT

1967 ◽  
Vol 37 (4) ◽  
pp. 463-469 ◽  
Author(s):  
EVELYN C. BLENKINSOPP ◽  
W. K. BLENKINSOPP
Keyword(s):  
Continuous Infusion ◽  
Deoxyribonucleic Acid ◽  
Tritiated Thymidine ◽  
Blood Eosinophil ◽  
Consequent Reduction ◽  
Reticulo Endothelial System ◽  
Eosinophil Counts

SUMMARY The effects of single and continuous administrations of a synthetic gluco-corticoid (dexamethasone) on eosinophil numbers and distribution have been studied. Absolute blood eosinophil counts were made, and the turnover of the eosinophils was examined by continuous infusion of tritiated thymidine to label the deoxyribonucleic acid of all newly formed cells. Dexamethasone equivalent to less than 200 μg. cortisone/100 g. rat/day produced disappearance of eosinophils from the blood and the normal output of glucocorticoids is therefore probably less than this. Single administrations of dexamethasone produced a blood eosinopenia within 2 hr. due to removal and destruction of eosinophils by the reticulo-endothelial system. Continuous dexamethasone administration reduced the number of proliferating eosinophil cells in the marrow, with a consequent reduction in the number of eosinophils in the tissues.

Duration of Availability of Tritiated Thymidine Following Intraperitoneal Injection

1968 ◽  
Vol 3 (1) ◽  
pp. 89-93
Author(s):  
W. K. BLENKINSOPP
Keyword(s):  
Cell Division ◽  
Intraperitoneal Injection ◽  
Deoxyribonucleic Acid ◽  
Direct Evidence ◽  
Tritiated Thymidine ◽  
Indirect Evidence ◽  
Acid Synthesis ◽  
Single Intraperitoneal Injection ◽  
Deoxyribonucleic Acid Synthesis

Much indirect evidence supports the assumption that tritiated thymidine does not label cells which enter the deoxyribonucleic acid synthesis phase (S) more than 1 h after injection. Direct evidence confirming this assumption was obtained by counting labelled epithelial nuclei in mice killed 1, 4 or 6 h after a single intraperitoneal injection of [3H]thymidine; colchicine was used to prevent the increase in number of labelled nuclei which would otherwise have occurred because of cell division. The proportion of cells labelled was the same at 1 h as at 4 or 6 h after injection of [3H]thymidine. Nuclei were regarded as labelled if they were overlaid by 4 grains or more; comparison of nuclear and background labelling indicated that nuclei overlaid by 3 grains or less represented background labelling.

Effect of α-particle and X-ray irradiation on DNA synthesis in tissue cultures

1961 ◽  
Vol 154 (957) ◽  
pp. 557-570 ◽  
Keyword(s):  
Hela Cell ◽  
Tritiated Thymidine ◽  
Single Layer ◽  
Target Volume ◽  
Mouse Fibroblast ◽  
Synthesis Rate ◽  
X Rays ◽  
X Ray ◽  
Thin Thread ◽  
Thymidine Autoradiography

The effects of both α-particle and X-ray in radiation, on the DNA synthesis rate in mouse fibroblast and Hela cells in tissue culture is described. Tritiated thymidine autoradiography was used to indicate the rate of DNA synthesis in the single-layer cultures used. The results of these experiments show that: (1) The fraction of cells in a culture synthesizing DNA is not markedly affected by α-particles and X-rays in the dose used in the experiment. (2) The effect of either type of radiation is to reduce the rate of synthesis of DNA of the irradiated cells in synthesis. (3) The effect of a given dose of either type of radiation is to reduce the rate of synthesis of all the cells to a constant fraction of what it was in the unirradiated cells. (4) The rate of DNA synthesis is reduced to 37 % (1/ e ) by a dose of ca . 25 α/μ 2 or an X-ray dose of 14000 rads for mouse fibroblast cultures. In Hela cell cultures a dose of ca . 90000 rads is needed to reduce the rate of DNA synthesis to 37 % of the initial value. (5) The reduction in synthesis occurs not more than half an hour after irradiation and may be an immediate effect. From (4) above the target shape can be roughly calculated and if it is assumed to be cylindrical it appears to have dimensions 16 Å in one direction and 160000 Å in the other, i. e. a long thin thread with a mol. wt. of ca . 5 x 10 7 in the case of the mouse fibroblast experiments. In the case of the Hela cell experiments the target volume gives a mol. wt. of ca . 10 7 . These results are consistent with the view that the target may possibly be the DNA template (or maybe DNP because of the high value for the molecular weight in one case). If the effects described reflect damage to the DNA (or DNP ) template during the exponented phase of synthesis then observations, (1) (2), and (3) above follow as obvious corollaries.

An Effect of Tritiated Thymidine on the Incorporation of Thymidine into Chromosomal Deoxyribonucleic Acid

Nature ◽  
1960 ◽  
Vol 188 (4749) ◽  
pp. 511-512 ◽  
Author(s):  
MARGARIDA KRAUSE ◽  
W. PLAUT
Keyword(s):  
Deoxyribonucleic Acid ◽  
Tritiated Thymidine
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