The effects of indium-111 decay on pBR322 DNA
- Harvard Medical School, Boston, MA (United States)
- Univ. of Nebraska, Omaha, NE (United States)
We have compared the effectiveness in causing DNA strand breaks of {sup 111}In bound to DNA or free in aqueous solution with that of {gamma} rays. Supercoiled DNA from pBR322 plasmid labeled with [{sup 3}H]thymidine was purified and mixed with {sup 111}InCl{sub 3} in the absence of presence of diethylenetriaminepentaacetic dianhydride (DTPA), a metal chelator which prevents the binding of indium to DNA. The reaction mixtures were stored at 4{degrees}C to accumulate radiation dose from the decay of {sup 111}In. The DNA was then resolved by gel electrophoresis into supercoiled, nicked circular and linear forms, representing undamaged DNA, single-strand breaks (SSBs) and double-strand breaks (DSBs), respectively. The D{sub o} values of pBR322 DNA exposed to {gamma} radiation from an external {sup 137}Cs source and the decay of {sup 111}In dispersed in solution (+DTPA) are 3.1 {+-} 0.1 and 2.8 {+-} 0.1 Gy, respectively. In terms of accumulated {sup 111}In disintegrations cm{sup {minus}3} of plasmid DNA solution, the D{sub o} value is 15.3 ({+-} 0.7) x 10{sup 10} disintegrations in the absence of DTPA and 38.2 ({+-} 1.1) x 10{sup 10} disintegrations in its presence. Since only 14.6 {+-} 5% of the {sup 111}In was bound to DNA in the absence of DTPA, an effective D{sub o} for bound {sup 111}In of 3.4 ({+-} 1.1) x 10{sup 10} disintegrations is obtained. The 11-fold (range 9- to 17-fold) increased effectiveness of this Auger electron emitter when in proximity to DNA appears to be due mainly to the higher yield of SSBs. 34 refs., 4 figs., 3 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 68622
- Journal Information:
- Radiation Research, Journal Name: Radiation Research Journal Issue: 2 Vol. 141; ISSN 0033-7587; ISSN RAREAE
- Country of Publication:
- United States
- Language:
- English
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