Mutations caused by ion beams have been well-studied in plants, including ornamental flowers, rice, and algae. It has been shown that ion beams have several significantly interesting features, such as a high biological effect and unique mutation spectrum, which is in contrast to low linear energy transfer (LET) radiation such as gamma rays. In this study, the effects of double strand breaks and 8-oxo-2′-deoxyguanosine (8-oxodG) caused by ion-beam irradiation were examined. We irradiated repair-gene-inactive strains rad52, ogg1, and msh2 using carbon ion beams, analyzed the lethality and mutagenicity, and characterized the mutations. High-LET carbon ion-beam radiation was found to cause oxidative base damage, such as 8-oxodG, which can lead to mutations. The present observations suggested that nucleotide incorporation of oxidative damage gave only a limited effect on cell viability and genome fidelity. The ion-beam mutations occurred predominantly in 5′-ACA-3′ sequences, and we detected a hotspot at around +79 to +98 in URA3 in wild-type and mutant lines, suggesting the presence of a mutation-susceptible region.

Ionizing radiation can originate from naturally occurring radiation sources on the earth or it can be from man-made sources. When interacting with cells and living organisms, ionizing radiation produces free radicals, impacting biological molecules such as proteins, lipids, and DNA in the cell nucleus and membrane, leading to cell death or causing cell mutations. Epigallocathecin gallate (EGCG) and ascorbic acid (AA) are well-known natural antioxidants that have been studied and applied as potential radical scavengers. In this study, the radiation protection effects in the presence of EGCG and AA via the scavenging process of free radicals (mainly hydroxyl radicals) were examined. Saccharomyces cerevisiae yeast cells were grown in YDP liquid medium containing yeast extract, peptone, and dextrose/glucose that supplemented with EGCG and AA at different concentrations. Then, the cell cultures were irradiated with both low (gamma) and high (helium ion beam) linear energy transfer (LET) radiations to evaluate the radiation effect on the survival of the yeast cell. Both of EGCG and AA play effectively important roles as radiation-protective agent for yeast cells and the effectiveness in radiation protection of EGCG and AA at the same concentration was almost the same between these two additives

We developed a novel dosimetric method using DNA molecules as a radiation sensor. The amount of neutron or gamma rays irradiated DNA damage was determined by evaluating the amount of DNA serving as a template for qPCR. The absorbed doses in the samples were estimated using the tally of the “t-product” in the data from the PHITS Monte Carlo particle transport simulation code. The neutron fluence for each sample was measured using the niobium activation reaction ⁹³Nb (n, 2n) ^92mNb, and the absorbed dose per neutron fluence was estimated to be 7.1 × 10⁻¹¹ Gy/(n/cm²). Based on the PHITS modeling, the effects of neutron beams are attributed to the combination of proton and alpha particle beams. The results from qPCR showed that neutrons caused more DNA damage than gamma rays. The qPCR method demonstrated that neutron irradiation caused 1.13-fold more DNA damage compared to gamma ray irradiation; however, this result did not show a statistically significant difference. This method we developed, using DNA molecules as a radiation sensor, may be useful for biodosimetry.