Low-Energy Ion-Species-Dependent Induction of DNA Double-Strand Breaks: Ion Energy and Fluence Thresholds

Abstract

The goal of this study was to determine the critical ion-radiation conditions under which heavy ion beams can induce DNA double-strand breaks. Helium, nitrogen and argon-ion beams in the energy range of 20 eV to 2 keV were used to irradiate naked DNA plasmid pGFP to fluences of 1, 2 and 4 × 10 ions/cm. The topological forms of DNA were subsequently analyzed using gel electrophoresis. The DNA forms were changed from the original supercoiled to damaged relaxed and linear forms, depending on the ion mass, energy, fluence and inertia. We found ion energy and fluence thresholds above which direct double-strand breaks can occur. The threshold is discussed in terms of the areal ion-energy density and the cross-section.

Isolation, Mutagenesis, and Organic Acid Secretion of a Highly Efficient Phosphate-Solubilizing Fungus

“…Low-energy ion beam mutagenesis leads to single base substitution and DNA double-strand breakage ( Thopan et al, 2017 ), and a large number of free radicals will be produced. Mutation breeding of highly efficient phosphate-solubilizing fungi microorganisms and characterization of the underlying phosphate-solubilizing mechanism has always been hot research topics in the field of soil microorganisms and biofertilizers ( Guo et al, 2019 ).…”

A Discussion on Associating THz Safety with 5G Safety

“…[48][49][50] In vitro study of THz radiation effect on DNA changes, based on the concept and protocol of a series of our previous experiments on low-energy ion-beam bombardment of naked DNA. [39,40] The experimental steps are briefed. 1) DNA samples of pGFP (plasmid with the marker gene of green fluorescent protein) as well as bacteria Escherichia coli (E. coli) for DNA transfer to check mutation induction are prepared.…”

“…If the low‐energy ion‐beam current is about 20 nA, [ 39 ] the irradiation time for that fluence is about 10 4 s and then the ion‐energy deposition rate per unit area is 10 12 eV cm −2 s −1 , which is able to cause DNA change or damage in terms of strand breaks. [ 40 ] Then, what about 1 mW 1 THz which has the energy deposition rate per unit area about 100 times that of the ion beam? Each photon's energy is too low to change DNA atoms, but what if a large number of photons strikes the DNA atoms in a short time period.…”

Fruits and their phytochemicals in mitigating the ill effects of ionizing radiation: review on the existing scientific evidence and way forward

“…2 Radiation causes the generation of free radicals like RNS and ROS in cells, thereby causing injury to cells and tissues by damaging the biological macromolecules, especially the DNA. 6,7 Radiation can also cause direct DNA damage like DNA cross-links, SSBs, DSBs, and DNA-protein cross-links. Exposure to radiotherapy also disturbs the cellular functions of cell membranes and organelles and alters the cell signal transduction and regulation pathways.…”