NUCLEAR UPTAKE OF DNA FRAGMENTS AFTER INJECTION OF $sup 32$P-LABELLED THYMOCYTES IN LETHALLY IRRADIATED MICE
Twenty-four hours after total-body irradiation with 800 r mice were injected with a suspension of homologous living P/sup 32/ thymocytes, with a suspension of P/sup 32/ thymocytes killed by ultraviolet irradiation, and with a corresponding amount of P/sup 32/ in the form of Na/sub 2/H /sup 32/PO/sub 4/. There was greater re tention of radioactivity at 24 and 48 hr after the injection of cells than after the injection of inorganic P/sup 32/ in the spleen and liver. Labeled cells morphologically identical with thymocytes were found only in the thymus, bone marrow, and spleen. After the injection of living or dead cells, as well as after the injection of inorganic P/sup 32/, diffuse radioactivity was found in the thymus, spleen, and bone-marow autoradiographs. The sinusoids and cytoplasm, as well as the nuclei of liver cells, were active in the liver: the vessel lumina, glomerular capillaries, both layers of Bowman's capsule and proximal, less frequently also the distal tubules in the kidney; the epithelium surface, intercellulear spaces and blood vessels of the mucous membrane, and, diffusely, the crypt epithelium were active in the duodenum. After the removal of all non-DNA phosphorus and after injection of living or dead thymocytes, labeled lymphocyte-type cells were found, as well as Feulgen positive fragments in the thymus, spleen, and bone marrow. Up to 3 hr after injection, the label was observed in the nuclei of reticular cells of the thymus, spleen, and bone marrow; in the nuclei of the endosteal cells of the femur; in the neutrophils; and in the cytoplasm of the reticular and endosteal cells. After the injection of inorganic P/sup 32/, activity of DNA-P/sup 32/ was found only in two mice of the 3-hr stage; it was confined to the same types of cells as those found after the injection of cell suspensions. It is suggested that the activity of nuclei of resting cells of the thymus, spleen, and bone marrow is caused by the uptake of large DNA fragments of injected and disintegrated P/sup 32/ thymocytes. In the case of injection of inorganic P/sup 32/, the findings are interpreted by the uptake of DNA-P/sup 32/ originating from the thymocytes that disintegrated after beling labeled during premitotic DNA synthesis. (auth)
- Research Organization:
- Inst. of Biophysics, Czechoslovak Academy of Sciences, Brno
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-15-008546
- OSTI ID:
- 4104148
- Journal Information:
- Exptl. Cell Research, Journal Name: Exptl. Cell Research Vol. Vol: 21
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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