Carbon Ion Beam Irradiation Research Articles

Responses of hematopoietic cells after ionizing-irradiation in anemic adult medaka (Oryzias latipes)

Purpose Hematopoietic tissues of vertebrates are highly radiation sensitive and the effects of ionizing radiation on the hematopoiesis have been studied in mammals and teleosts for decades. In this study, radiation responses in the kidney, the main hematopoietic organ in teleosts, were investigated in Japanese medaka (Oryzias latipes), which has been a model animal and a large body of knowledge has been accumulated in radiation biology. Methods Kidney, the main hematopoietic tissue of adult medaka fish, was locally irradiated using proton and carbon ion beams irradiation system of Takasaki Ion Accelerator for Advanced Radiation Application (TIARA), QST, and the effects on peripheral blood cells and histology of the kidney were investigated. Results When only kidneys were locally irradiated with proton or carbon ion beam (15 Gy), the hematopoietic cells in the irradiated kidney and cell density in the peripheral blood decreased 7 days after the irradiation in the same manner as after the whole-body irradiation with γ-rays (15 Gy). These results demonstrate that direct irradiation of the hematopoietic cells in the kidney induced cell death and/or cell cycle arrest and stopped the supply of erythroid cells. Then, the cell density in the peripheral blood recovered to the control level within 4 days and 7 days after the γ-ray and proton beam irradiation (15 Gy), respectively, while the cell density in the peripheral blood did not recover after the carbon ion beam irradiation (15 Gy). The hematopoietic cells in the irradiated kidneys temporarily decreased and recovered to the control level within 21 days after the γ-ray or proton beam irradiation (15 Gy), while it did not recover after the carbon ion beam irradiation (15 Gy). In contrast, the recovery of the cell density in the peripheral blood delayed when anemic medaka were irradiated 1 day after the administration of phenylhydrazine. With and without γ-ray irradiation, a large number of hematopoietic cells was still proliferating in the kidney 7 days after the anemia induction. Conclusions The results obtained strongly suggest that the hematopoietic stem cells in medaka kidney prioritize to proliferate and increase peripheral blood cells to eliminate anemia, even when they are damaged by high-dose irradiation.

Near-infrared single-mode optical waveguide fabrication in LiF crystal by carbon ion irradiation

In this study, a carbon-ion beam irradiation method with energy of 6.0 MeV was employed to prepare single-mode optical waveguide structures in LiF single crystal. The results of this study reveal that the visible light and near-infrared laser beams can be well-confined in the irradiated region that is influenced by the irradiation fluences. An end-face coupling system was used to estimate the propagation loss (1.3 dB cm−1) after annealing treatment. The surface damage of the irradiated regions in LiF was analysed based on the displacements per atom calculation using the stopping and range of ions in matter code.

Carbon-Ion Beam Radiosensitivity Study and Biological Responses of High-Yielding Rice Line, MR219-PL-5

The carbon ion-beam has emerged as a novel physical mutagen for creating genetic variability and crop improvement. In this study, seeds of a high-yielding pyramided rice line MR219-PL-5 were exposed to carbon ion beam irradiation at 10, 20, 40, 60, 80, and 100 Gy. The radiosensitivity test was conducted to determine the optimum dose of carbon ion beam irradiation based on the lethal dose 50% (LD50) using Sandwich Blotter Technique. The biological responses of carbon-ion beam irradiation were also observed in other characteristics such as germination rate (GeR), survival rate (SR), growth rate (GRoR), shoot length (SL), root length (RL), seedling height (SH), days to flowering (DTF), fertility rate (FR) and thousand-grains weight (TGW). Based on the polynomial curve of SR graph, the lethal dose 50% (LD50) value was 86.12 Gy. However, the optimum dose range of carbon ion-beam irradiation was between 40 and 60 Gy as these two doses recorded the highest SR, 63 and 67%, respectively. Furthermore, the shoulder dose in this study was 60 Gy since SR decreased significantly at higher doses. M1 individuals irradiated at 40 and 60 Gy had the best biological responses where significant differences were found for SR, SL, RL, GRoR, SH, DTF and FR at these two doses compared to the other doses. Further studies on M2 and M3 populations could help to identify potential individuals as well as to understand the inheritance of each trait of interest from one generation to the next.

Genome and transcriptome-based characterization of high energy carbon-ion beam irradiation induced delayed flower senescence mutant in Lotus japonicus

BackgroundFlower longevity is closely related to pollen dispersal and reproductive success in all plants, as well as the commercial value of ornamental plants. Mutants that display variation in flower longevity are useful tools for understanding the mechanisms underlying this trait. Heavy-ion beam irradiation has great potential to improve flower shapes and colors; however, few studies are available on the mutation of flower senescence in leguminous plants.ResultsA mutant (C416) exhibiting blossom duration eight times longer than that of the wild type (WT) was isolated in Lotus japonicus derived from carbon ion beam irradiation. Genetic assays supported that the delayed flower senescence of C416 was a dominant trait controlled by a single gene, which was located between 4,616,611 Mb and 5,331,876 Mb on chromosome III. By using a sorting strategy of multi-sample parallel genome sequencing, candidate genes were narrowed to the gene CUFF.40834, which exhibited high identity to ethylene receptor 1 in other model plants. A physiological assay demonstrated that C416 was insensitive to ethylene precursor. Furthermore, the dynamic changes of phytohormone regulatory network in petals at different developmental stages was compared by using RNA-seq. In brief, the ethylene, jasmonic acid (JA), and salicylic acid (SA) signaling pathways were negatively regulated in C416, whereas the brassinosteroid (BR) and cytokinin signaling pathways were positively regulated, and auxin exhibited dual effects on flower senescence in Lotus japonicus. The abscisic acid (ABA) signaling pathway is positively regulated in C416.ConclusionSo far, C416 might be the first reported mutant carrying a mutation in an endogenous ethylene-related gene in Lotus japonicus, rather than through the introduction of exogenous genes by transgenic techniques. A schematic of the flower senescence of Lotus japonicus from the perspective of the phytohormone regulatory network was provided based on transcriptome profiling of petals at different developmental stages. This study is informative for elucidating the molecular mechanism of delayed flower senescence in C416, and lays a foundation for candidate flower senescence gene identification in Lotus japonicus. It also provides another perspective for the improvement of flower longevity in legume plants by heavy-ion beam.

Physio-Biochemical and Transcriptional Responses to Heat Stress in Seedlings Following Carbon Ion Beam Irradiation of Arabidopsis Seeds

Physio-Biochemical and Transcriptional Responses to Heat Stress in Seedlings Following Carbon Ion Beam Irradiation of Arabidopsis Seeds

Time Course Analysis of Genome-Wide Identification of Mutations Induced by and Genes Expressed in Response to Carbon Ion Beam Irradiation in Rice (Oryza sativa L.).

Heavy-ion irradiation is a powerful mutagen and is widely used for mutation breeding. In this study, using whole-genome sequencing (WGS) and RNA sequencing (RNA-seq) techniques, we comprehensively characterized these dynamic changes caused by mutations at three time points (48, 96, and 144 h after irradiation) and the expression profiles of rice seeds irradiated with C ions at two doses. Subsequent WGS analysis revealed that more mutations were detected in response to 40 Gy carbon ion beam (CIB) irradiation than 80 Gy of CIB irradiation at the initial stage (48 h post-irradiation). In the mutants generated from both irradiation doses, single-base substitutions (SBSs) were the most frequent type of mutation induced by CIB irradiation. Among the mutations, the predominant ones were C:T and A:G transitions. CIB irradiation also induced many short InDel mutations. RNA-seq analysis at the three time points showed that the number of differentially expressed genes (DEGs) was highest at 48 h post-irradiation. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of the DEGs showed that the “replication and repair” pathway was enriched specifically 48 h post-irradiation. These results indicate that the DNA damage response (DDR) and the mechanism of DNA repair tend to quickly start within the initial stage (48 h) after irradiation.

Carbon-Ion Beam Irradiation and the miR-200c Mimic Effectively Eradicate Pancreatic Cancer Stem Cells Under in vitro and in vivo Conditions.

PurposeThe study investigated the molecular mechanisms that killed pancreatic cancer cells, including cancer stem cells (CSCs), by carbon ion beam irradiation alone or in combination with miRNA-200c under in vitro and in vivo conditions.MethodsHuman pancreatic cancer (PC) cells, PANC1 and PK45, were treated with carbon-ion beam irradiation alone or in combination with microRNA-200c (miR-200c) mimic. Cell viability assay, colony and spheroid formation assay, quantitative real-time PCR analysis of apoptosis-, autophagy-, and angiogenesis-related gene expression, xenograft tumor control and histopathological analyses were performed.ResultsThe cell viability assay showed that transfection of the miRNA-200c (10 nM) mimic into pancreatic CSC (CD44+/ESA+) and non-CSC (CD44-/ESA-) significantly suppressed proliferation of both types of cell populations described above. Combining carbon-ion beam irradiation with the miRNA-200c mimic significantly reduced the colony as well as spheroid formation abilities compared to that observed with the treatment of carbon-ion beam alone or X-ray irradiation combined with the miRNA-200c mimic. Moreover, the combination of carbon ion beam irradiation and miRNA-200c mimic increased the expression of apoptosis-related gene BAX, autophagy-related genes Beclin-1 and p62, addition of gemcitabine (GEM) further enhanced the expression of these genes. In vivo data showed that carbon-ion beam irradiation in combination with the miRNA-200c mimic effectively suppressed xenograft tumor growth and significantly induced tumor necrosis and cavitation.ConclusionThe combination of miRNA-200c mimic and carbon ion beam irradiation may be powerful radiotherapy that significantly kills pancreatic cancer cells containing CSCs and enhances the effect of carbon-ion beam irradiation compared to carbon-ion beam irradiation alone.

Comparative transcriptome analysis reveals candidate genes for leaf color formation in a thermo-sensitive leaf-color mutant generated by carbon-ion beam in green wandering Jew (Tradescantia fluminensis)

• Altered levels of chlorophyll and anthocyanin contents, and abnormal ultrastructural features of chloroplasts were detected in the thermo-sensitive leaf-color mutant of green wandering Jew. • RNA-Seq analysis identified 42 candidate genes involved in photosynthesis, 14 candidate genes for chlorophyll biosynthesis, and 13 candidate genes for flavonoid and anthocyanin biosynthetic pathways. • Chlorophyll fluorescence signals, and HPLC confirmed the gene expression levels obtained by RNA-Seq. Leaf color is considered a valuable trait when breeding ornamental plants. In this study, a novel thermo-sensitive leaf-color mutant ( mt ) of green wandering Jew was obtained through carbon-ion beam irradiation. Young leaves of the mt plant exhibited pink coloration under low temperature ( mt _7 ℃) and green coloration under normal temperature ( mt _25 ℃). However, young leaves of the wild type (WT) remained green under low and normal temperatures. Here, we compared the mt and WT in terms of their anatomical, physiological, transcriptomic, and metabolomic characteristics at 7 ℃ and 25 ℃. Histological analyses showed that the upper epidermis and palisade parenchyma of mt were fewer and smaller. Chloroplasts of mt _25 ℃ were abnormally inflated, and leucoplasts were present instead of chloroplasts in mt _7 ℃ leaves. Physiological experiments also showed that mt _7 ℃ had lower chlorophyll and carotenoid contents, and higher anthocyanin contents; however, the chlorophyll content in mt _25 ℃ leaves were higher than that in the WT. Transcriptome profiling revealed that 99 differentially expressed genes (DEGs) and 1597 transcription factors (TFs) are involved in photosynthesis, chlorophyll biosynthesis, and flavonoid and anthocyanin biosyntheses. This study identified 8 candidate genes associated with the PS Ⅱ reaction center, 13 genes related to PS Ⅰ, 15 genes for LHC, 4 genes for PET/Cyt b6/f, and 2 genes for ATP synthase; these genes were differentially expressed at 7 ℃. DEGs related to photosynthesis and chlorophyll biosynthesis were down-regulated in the pink leaves of mt _7 ℃, whereas DEGs involved in flavonoid and anthocyanin biosyntheses were up-regulated in mt _7 ℃ and mt _25 ℃ leaves. Differential expression levels were further confirmed by qRT-PCR, Chlorophyll fluorescence signals, and previous HPLC results the. The anthocyanin content of mt _7 ℃ was 20-fold higher than that of the other pigments resulting in pink coloration at low temperature. This study provides a systematic evaluation of thermo-sensitive color variation in the mt . Based on these results, we identified key pathways related to thermo-sensitive leaf-color change in green wandering Jew.

Effects of Carbon Ion Beam Irradiation on Phenotypic Variations and Biochemical Parameters in Early Generations of Soybean Plants

Understanding the characteristics of carbon ion beam irradiation-induced mutation is essential to its potential application in plant breeding. A carbon ion beam-mutagenized soybean population was generated from the newly released soybean variety Dongsheng 28, with irradiation dosages of 100 Gy, 120 Gy and 140 Gy. Many phenotypic variations and novel mutants with heritable tendencies including plant height mutants, sterile mutants, early mature mutants, rolled leaves and short petioles mutants, yield-related mutants and lodging-resistant mutants were identified. Diverse variations in seed size, seed protein and oil concentration were found. Increasing irradiation dosage from 100 Gy to 140 Gy increased leaf chlorophyll concentration in M1 generation, but this effect was significantly reduced in M2 generation. The activities of superoxide dismutase (SOD), peroxidase (POD) and malondialdehyde (MDA) concentration all showed wider variation in M1 and M2 generation, the only exception being that the MDA concentration was similar to the control in the M2 generation. Overall, we suggest that treating soybean seeds with carbon ion beam irradiation at a dosage of 120 Gy (80 Mev/u) could be effective in soybean mutation breeding.

Effects of Carbon Ion Beam Irradiation on Butanol Tolerance and Production of Clostridium acetobutylicum.

Clostridium acetobutylicum (C. acetobutylicum) has considerable potential for use in bioenergy development. Owing to the repeated use of traditional mutagenesis methods, the strains have developed a certain tolerance. The rheology of the bioprocess and the downstream processing of the product heavily depend on the ability of C. acetobutylicum mutants to produce butanol. Carbon ion beam irradiation has advantages over traditional mutation methods for fermentative production because of its dose conformity and superb biological effectiveness. However, its effects on the specific productivity of the strains have not been clearly understood. In this study, we screened five mutants through carbon ion beam irradiation; mutant Y217 achieved a butanol-production level of 13.67 g/L, exceeding that of wild-type strain ATCC 824 (i.e., 9.77 g/L). In addition, we found that the mutant maintained normal cell membrane integrity under the stimulation of 15 g/L butanol, whereas the intracellular macromolecules of wild-type strain ATCC 824 leaked significantly. Subsequently, we used the response surface methodology (RSM) to determine if the mutant cell membrane integrity improved the butanol tolerance. We verified that with the addition of butanol, the mutant could be fermented to produce 8.35 g/L butanol, and the final butanol concentration in the fermentation broth could reach 16.15 g/L. In this study, we proved that under butanol stress, mutant Y217 features excellent butanol production and tolerance and cell membrane integrity and permeability; no prior studies have attempted to do so. This will serve as an interesting and important illustration of the complexity of genetic control of the irradiation mutation of C. acetobutylicum strains. It may also prove to be useful in the bioengineering of strains of the mutant for use in the predevelopment stage.

Superior Effect of the Combination of Carbon-Ion Beam Irradiation and 5-Fluorouracil on Colorectal Cancer Stem Cells in vitro and in vivo.

BackgroundThe aim of this study was to investigate whether carbon-ion beam irradiation in combination with 5-fluorouracil (5-FU) is superior to carbon-ion beam irradiation alone in targeting colorectal cancer stem-like cells (CSCs).Materials and MethodsHuman colorectal cancer (CRC) cells, HCT116 and HT29, were treated with carbon-ion beam irradiation alone or in combination with 5-FU. Cell viability assay, colony and spheroid formation assay, apoptotic assay, and quantitative real-time PCR analysis of apoptosis- and autophagy-related gene expression were performed.ResultsCarbon-ion beam irradiation dose-dependently decreased CRC cell viability and showed significantly enhanced cell killing effect when combined with 5-FU. Carbon-ion beam irradiation in combination with 5-FU significantly increased the percentage of apoptotic cells. The expression of some apoptotic and autophagy-related genes such as Bax, Bcl2, Beclin1 and ATG7 was significantly induced by carbon-ion beam irradiation alone and was further enhanced when the beam was combined with 5-FU. The spheroid forming capacity of CD133+ cell subpopulations was significantly inhibited by carbon-ion beam in combination with 5-FU. Histopathologically, the combination of carbon-ion beam irradiation and 5-FU destroyed more xenograft tumor cells, and resulted in increased necrosis, cavitation, and fibrosis, compared to carbon-ion beam irradiation alone.ConclusionIn conclusion, carbon-ion beam treatment combined with 5-FU has the potential to kill CRC cells including CSCs by inducing increased apoptosis and autophagy.

Use of a Si/CdTe Compton Camera for In vivo Real-Time Monitoring of Annihilation Gamma Rays Generated by Carbon Ion Beam Irradiation.

The application of annihilation gamma-ray monitoring to the adaptive therapy of carbon ion radiotherapy (C-ion RT) requires identification of the peak intensity position and confirmation of activated elements with annihilation gamma-rays generated at the C-ion-irradiated site from those transported to unirradiated sites. Real-time monitoring of C-ion-induced annihilation gamma-rays was implemented using a Compton camera in a mouse model. An adult C57BL/6 mouse was anesthetized, and C-ion beams were directed into the abdomen at 1 × 109 particles/s for 20 s. The 511 keV annihilation gamma-rays, generated by the interaction between the irradiated C-ion beam and the target mouse, were detected using a silicon/cadmium telluride (Si/CdTe) Compton camera for 20 min immediately after irradiation. The irradiated site and the peak intensity position of 511 keV gamma emissions due to C-ion beam irradiation on a mouse were observed at the abdomen of the mouse by developing Compton images. Moreover, the positron emitter transport was observed by evaluating the range of gamma-ray emission after the C-ion beam irradiation on the mouse. Our data suggest that by confirming the peak intensity and beam range of C-ion RT with Si/CdTe-based Compton camera, it would be possible to reduce the intra-fractional and inter-fractional dose distribution degradation. Therefore, the results of this study would contribute to the future development of adaptive therapy with C-ion RT for humans.

Carbon-Ion Beam Irradiation Alone or in Combination with Zoledronic acid Effectively Kills Osteosarcoma Cells.

Osteosarcoma (OSA) is the most common malignant bone tumor in children and adolescents. The overall five-year survival rate for all bone cancers is below 70%; however, when the cancer has spread beyond the bone, it is about 15–30%. Herein, we evaluated the effects of carbon-ion beam irradiation alone or in combination with zoledronic acid (ZOL) on OSA cells. Carbon-ion beam irradiation in combination with ZOL significantly inhibited OSA cell proliferation by arresting cell cycle progression and initiating KHOS and U2OS cell apoptosis, compared to treatments with carbon-ion beam irradiation, X-ray irradiation, and ZOL alone. Moreover, we observed that this combination greatly inhibited OSA cell motility and invasion, accompanied by the suppression of the Pi3K/Akt and MAPK signaling pathways, which are related to cell proliferation and survival, compared to individual treatments with carbon-ion beam or X-ray irradiation, or ZOL. Furthermore, ZOL treatment upregulated microRNA (miR)-29b expression; the combination with a miR-29b mimic further decreased OSA cell viability via activation of the caspase 3 pathway. Thus, ZOL-mediated enhancement of carbon-ion beam radiosensitivity may occur via miR-29b upregulation; co-treatment with the miR-29b mimic further decreased OSA cell survival. These findings suggest that the carbon-ion beam irradiation in combination with ZOL has high potential to increase OSA cell death.

Significance of PD-L1 expression in carbon-ion radiotherapy for uterine cervical adeno/adenosquamous carcinoma.

ObjectiveProgrammed cell death-ligand 1 (PD-L1) is expressed in tumor cells and has been shown to predict clinical outcomes of several types of malignancies. The aim of this study was to investigate the effects of carbon-ion (C-ion) beam irradiation on PD-L1 expression in human uterine cervical adeno/adenosquamous carcinoma (UCAA) cells and clinical samples and to identify the prognostic factors for outcomes after C-ion radiotherapy (CIRT).MethodsThe effects of C-ion irradiation on PD-L1 expression in human UCAA and cervical squamous cell carcinoma cells were examined by flow cytometry. We examined PD-L1 expression in UCAA biopsy specimens from 33 patients before CIRT started (pre-CIRT) and after 12 Gy (relative biological effectiveness [RBE]) irradiation (post-12Gy-C) in 4 fractions of CIRT to investigate the correlation between PD-L1 status and clinical outcomes.ResultsThe PD-L1 expression was upregulated by C-ion beam in a dose-dependent manner in HeLa and SiHa cells through phosphorylated Chk1. The overall frequencies of pre-CIRT and post-12Gy-C PD-L1 positivity were 45% (15/33) and 67% (22/33), respectively. The post-12Gy-C PD-L1 expression was significantly elevated compared to the pre-CIRT PD-L1 expression. There was no significant relationship between the pre-CIRT PD-L1 status and clinical outcomes, such as local control (LC), progression-free survival (PFS), and overall survival (OS). However, the post-12Gy-C PD-L1 expression had better correlation with PFS, but not with LC and OS.ConclusionCIRT can induce PD-L1 expression in UCAA and we propose that PD-L1 expression after starting CIRT may become as a predictive prognostic marker in CIRT for UCAA.

Genome-Wide Comparisons of Mutations Induced by Carbon-Ion Beam and Gamma-Rays Irradiation in Rice via Resequencing Multiple Mutants.

Physical mutagens, such as carbon-ion beams (CIBs) and gamma rays (GRs), induce mutations with high frequency at a relatively low dose and are more user-friendly and environment-friendly in mutation breeding. Previous studies showed that CIBs induced large sized deletions and insertions, and chromosomal rearrangements, whereas GRs induce shorter deletions and insertions, and more frequent base substitutions. However, the difference on the genomic level between CIB- and GR-induced mutations remains to be clarified. In the present study, we re-sequence six mutagenized lines derived from CIB irradiation and four mutagenized lines derived from GRs. A total of 283 and 381 variations are induced in these mutants by CIBs and GRs, respectively, including single base substitutions (SBSs), small insertion and deletions (InDels), multiple nucleotide variants (MNVs). SBSs are the most abundant type of mutation and single base transition is the main form for SBSs. CIB-induced InDels accounted for 25.44% of the total variations, while GR-induced InDels accounted for 17.85%. On the contrary, the frequency of MNVs induced by GRs was approximately 2.19 times that induced by CIBs, which indicates CIBs induced increased InDels, whereas GRs induced increased MNVs. Notably, multiple base deletions (≥5 bp) were induced at a much higher frequency by CIBs than by GRs. We also find mutations induced by CIBs and GRs are unevenly distributed on chromosomes. Unusual high-frequency (HF) and low-frequency (LF) mutation regions are discovered by analyzing mutations per 1Mb along the genome. The mutation frequency within the HF regions were significantly higher than the LF regions (P < 0.05). A large majority of SBSs, InDels, and MNVs induced by CIBs and GRs occurred in upstream and downstream regions. Our study compares difference of mutation profiles induced by the CIB irradiation and GR on rice genomes, and give some clues for understanding the mutagenesis mechanism of physical radiation and improving the mutagenesis efficiency.

Genetic polymorphisms in mutagenesis progeny of Arabidopsis thaliana irradiated by carbon-ion beams and γ-rays irradiations

Purpose: Heavy-ion beams and γ-rays are popular physical mutagenesis to generate mutations in higher plants. It has been found that they show different mutation frequencies and spectrums of phenotype induction, however, the characteristics of heavy-ion beams on genetic polymorphism have not been clarified by comparing with γ-rays.Materials and methods: In the present study, seeds of Arabidopsis thaliana were exposed to carbon-ion beams (with linear energy transfer (LET) of 50 keV/μm) and γ-rays (with average LET of 0.2 keV/μm) irradiation. By using inter-simple sequence repeat (ISSR) and random amplified polymorphic DNA (RAPD) analysis, the genetic polymorphism of both M1 and M3 plants were investigated, respectively.Results: Carbon-ion beams induced relatively higher polymorphism rate in both M1 and M3 generation than γ-rays: the polymorphism rates of M1 plants derived from carbon-ion beams irradiation are 12.87% (ISSR-C) and 9.01% (RAPD-C), while are 7.67% (ISSR-γ) and 1.45% (RAPD-γ) of plants derived from γ-rays. In M3 generation, the polymorphism rates of ISSR-C, RAPD-C, ISSR-γ, and RAPD-γ are 17.64%, 22.79%, 12.10%, and 2.82%, respectively.Conclusions: In summary, the exposure to carbon-ion beams and γ-rays lead to the change of genomic DNA of A. thaliana, which could be tested in M1 plants and M3 plants by ISSR and RAPD technology. So, both carbon-ion beams and γ-rays can induce variations of genetic polymorphisms in M1 plants and M3 plants. The genetic polymorphisms of M1 plants and M3 plants induced by carbon-ion beams are higher than γ-rays, indicating that heavy-ion beams irradiations mutation breeding is more advantageous than conventional ionizing radiations. Average molecular polymorphism of M1 plants is lower than M3 mutants, by nearly 4.77% (ISSR-C), 13.78% (RAPD-C), 4.43% (ISSR-γ), and 1.37% (RAPD-γ). We hope our study will provide basic information for understanding the effects of carbon-ion beams and γ-rays for plant mutation breeding.

Precise tuning chemistry and tailoring defects of graphene oxide films by low energy ion beam irradiation

Precise tuning chemistry and tailoring nanopores of graphene oxide (GO) thin films are vital for their application for liquid and gas separation. In this work, ultra-thin GO films with thicknesses of about 150 nm were prepared and then modified by a low energy carbon ion beam with ion fluences ranging from 1 × 1015 ions·cm−2 to 1 × 1017 ions·cm−2. An ion fluence of 1 × 1016 ions·cm−2 is a threshold for the changes to the surface geometry (i.e. the chemical state and the consequent morphology) of the GO films. Moreover, X-ray photoelectron spectroscopy (XPS) reveals that oxygen loss in ion beam-induced reduction of GO films was mainly by the elimination of the unstable CO species. Raman spectroscopy indicates that a mass of defects with a mean defect distance of about 1.4 nm was generated in GO films by C+ irradiation. According to SRIM simulation, an average of 208 carbon vacancies were created in the GO film per impinging C+. These results suggest that low energy carbon ion beam irradiation is promising for simultaneously reducing and drilling nanoscale pores on GO surfaces in a controllable manner, which could be used for engineering GO-based separation membranes.

Effects of Magnetic Field Applied Just Before, During or Immediately after Carbon-Ion Beam Irradiation on its Biological Effectiveness.

Previously reported studies have revealed that the application of a magnetic field longitudinal to a carbon-ion beam enhances its biological effectiveness. Here we investigated how timing of the magnetic field application with respect to beam irradiation influenced this effect. Human cancer cells were exposed to carbon-ion beams with linear energy transfer (LET) of 12 and 50 keV/µm. The longitudinal magnetic field of 0.3 T was applied to the cells just before, during or immediately after the beam irradiation. The effects of the timing on the biological effectiveness were evaluated by cell survival. The biological effectiveness increased only if the magnetic field was applied during beam irradiation for both LETs.

Carbon ion and proton beam irradiation of a normal human TK6 lymphoblastoid cell line within a magnetic field of 1.0 tesla.

BackgroundConsidering the increasing simultaneous application of magnetic resonance imaging (MRI) for more precise photon radiotherapy, it will be likely for particle radiotherapy to adopt MRI for future image guiding. It will then be imperative to evaluate the potential biological effects of a magnetic field (MF) on particle irradiation. This study explores such effects on the highly radiosensitive TK6 lymphoblastoid human cell line.MethodsThe following three parameters were measured after irradiation with either carbon ion or proton beams using spread out Bragg peaks and applying different doses within a perpendicular 1.0 T MF: (1) cell survival fraction (14 days postirradiation), (2) treatment-specific apoptosis, which was determined through the measurement of population in the sub-G1 phase, and (3) cell cycle progression by means of flow cytometry. These were compared to the same parameters measured without an MF.ResultsThe clonogenic assay in both treatment groups showed almost identical survival curves with overlapping error bars. The calculated α values with and without an MF were 2.18 (σ=0.245) and 2.17 (σ=0.234) for carbon ions and 1.08 (σ=0.138) and 1.13 (σ=0.0679) for protons, respectively. Similarly, the treatment-specific apoptosis and cell cycle progression showed almost identical curves with overlapping error bars. A two-sample, unpooled t-test analysis was implemented for comparison of all mean values and showed p-values >0.05.ConclusionNo statistically significant difference in biological response of the TK6 cells was observed when they were irradiated using spreadout Bragg peaks within a perpendicular 1.0 T MF as compared to those, which received the same dose without the MF. This should serve as another supporting piece of evidence toward the implementation of MRI in particle radiotherapy, though further research is necessary.

Radiation-induced redox alteration in the mouse brain

Time courses of the redox status in the brains of mice after X-ray or carbon-ion beam irradiation were observed by magnetic resonance redox imaging (MRRI). The relationship between radiation-induced oxidative stress on the cerebral nervous system and the redox status in the brain was discussed.The mice were irradiated by 8-Gy X-ray or carbon-ion beam (C-beam) on their head under anesthesia. C-beam irradiation was performed at HIMAC (Heavy-Ion Medical Accelerator in Chiba, NIRS/QST, Chiba, Japan). MRRI measurements using a blood-brain-barrier-permeable nitroxyl contrast agent, MCP or TEMPOL, were performed using 7-T scanner at several different times, i.e., 5–10 h, 1, 2, 4, and 8 day(s) after irradiation. Decay rates of the nitroxyl-enhanced T1-weighted MR signals in the brains were estimated from MRRI data sets, and variation in the decay rates after irradiation was assessed.The variation in decay rates of MCP and TEMPOL after X-ray or C-beam irradiation was similar, but different variation patterns were observed between X-ray and C-beam. The apparent decay rate of both MCP and TEMPOL decreased due to the temporal reduction of blood flow in the brain several hours after X-ray and/or C-beam irradiation. After decreasing, the apparent decay rates of nitroxyl radicals in the brain gradually increased during the following days after X-ray irradiation or rapidly increased 1 day after C-beam irradiation. The sequential increase in nitroxyl decay rates may have been due to the oxidative atmosphere in the tissue due to ROS generation. X-ray and C-beam irradiation resulted in different redox responses, which may have been due to time-varying oxidative stress/injury, in the mouse brain. The C-beam irradiation effects were more acute and larger than those of X-ray irradiation.