An Enzymic Detection of Single-Strand DNA Breaks Produced with Synchrotron Radiation (SR), Gamma-Ray, Proton- or Deuteron-Beam in Dry Nuclear DNA from Barley Seed

Abstract

We aimed to detect 3'-hydroxy terminus of DNA single-strand break (ssb) induced with different radiations using a specific enzyme reaction. Dry nuclear sample isolated from barley seeds and placed on the slides were exposed with a monochromic SR of 115, 160, 190, 210 and 260 nm-wavelength, gamma-ray, proton- or deuteron-beam, then DNA synthesis reaction was carried out on the sample using a mixture of ³H-TTP and DNA polymerase I of Escherichia coli et al. Then, microfluorography was carried out. Under the microscope, percentages of ³H-labeled nucleus and numbers of silver grains on a nucleus were observed. Consequently, it was proved that an 160 nm-SR was able to produce ssb on the nuclear DNA even with less than 0.5 V⋅min, while the other 190, 210 and 260 nm-SR yielded no ssb with lower intensity than 3 V⋅min. And, either proton- or deuteron-beam was strikingly effective than gamma-ray. From these data, we suggested that the DNA synthesis reaction is available to detect radiation-induced ssb.