STUDIES ON NUCLEI. II. EFFECTS OF X-RAYS ON DEOXYRIBONUCLEOPROTEIN FROM RAT THYMUS
One molar NaCI extracts of rat thymus are highly sensitive to x rays, and an exposure of 10 r causes a detectable loss in viscosity. An after effect was observed, and the viscosity of irradiated samples continued to decrease for 4 to 5 hours after irradiation. Dose curves were sigmoid. The effect of x rays on the extracts were largely indirect. Freezing, the addition of chemical protective agents, and increasing the concentration of the gell all had a dosereducing effect. There seemed to be a small contribution from direct effects not exceeding a few per cent of the total. Except for cyanide, all of the compounds tested that are known to protect animals from the lethal effects of irradiation also protected in the extracts. However, several compounds that had no protective action on animals gave large dose-reduction factors in the extracts. No good correlation exlsts between chemical agents protecting animals and those giving dose-reducing effects in the extracts. The high sensitivity of the extracts to x irradiation appeared to be a direct consequence of the high dilutions employed. Direct irradiation of the homogenate and excised tissue required, respectively, 100 and 700 times the x-ray dose neceseary to produce the aame effect in the extracts: The higher doses probably reflect protection from indirect effects by the high nonnentration of DNP in the cell nucleus and by protective substances such as proteins. The fact that one can demonatrate an effect by direct irradiation of the tissue is of interest, since no effects on DNA have been detected after irradiation in vivo. (auth)
- Research Organization:
- Oak Ridge National Lab., Tenn.; Duke Univ., Durham, N.C.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-14-006142
- OSTI ID:
- 4184489
- Journal Information:
- Exptl. Cell Research, Journal Name: Exptl. Cell Research Vol. Vol: 18
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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