60Co Γ-irradiation Research Articles

Effects of 60Coγ-irradiation combined with sodium dehydrogenate on post-harvest preservation and physiological indices of Volvariella volvacea.

Volvariella volvacea is a mushroom known for its high palatability and nutritional value. However, it is susceptible to spoilage thus making it challenging to preserve and keep fresh after harvest, resulting in constraints in long-distance transportation and long-term storage. This study aimed to investigate the feasibility of using irradiation and sodium dehydrogenate (SD) as a preservative in the preservation process of V. volvacea. The effects of three treatments of 0.8 kGy 60Coγ irradiation (B), 0.04% SD (C), combined with 0.04% SD and 0.8 kGy 60Coγ irradiation (A) on the postharvest freshness of V. volvacea were investigated. The assessment indices for V. volvacea, including appearance, browning rate, weight loss, respiration rate, MDA content, antioxidant enzyme activities, vitamin C (Vc), and soluble protein content, were measured and compared. The three treatments were compared to determine the changes in storage time over 7 days post-harvest. The results demonstrated that the hardness of the fruiting body exhibited a significant increase of 81.19%, 97.96% and 168.81% in comparison to the control, B and C, respectively, following the application of the treatment A. Compared to the control group, the soluble protein content was significantly increased by 20.28%. Respiration intensity and browning rate were significantly lower in the control treatment, decreasing by 35.07% and 45.49% respectively. On the 6th day of storage, the activities of SOD and POD increased by 81.06% and 73.71%, respectively, compared to the control, which significantly delayed the senescence of the fruiting bodies. The Vc content was significantly increased by 50.27%, 133.90%, and 101.39% in treatment B, which received 0.8 kGy 60Coγ irradiation alone, compared to the control, treatment A, and treatment C, respectively. The treatment C alone significantly reduced respiratory intensity and MDA variables by 39.55% and 31.01%, respectively, compared to the control. The findings can provide theoretical references and technical support for extending the preservation period of V. volvacea after harvesting by using irradiation and sodium dehydrogenate as a preservative.

Study on the preservation effect of 60Co-γ ray irradiation on potatoes

To evaluate the effect of irradiation on the preservation of potatoes, fresh potatoes were selected as the irradiation objects, and irradiated with 60Co-γ radiation source for 0, 100, 200, 500 and 1000 Gy, respectively. During the irradiation, the well-packaged Y1.79Bi0.01Eu0.2MgTiO6 novel thermoluminescence dosimeter material was placed together with the potatoes at the same position. Then, the potatoes were stored in the same temperature and humidity environment, and the quality changes of the potatoes were observed. The Y1.79Bi0.01Eu0.2MgTiO6 material had good performance indicators, and was used to measure the irradiation dose of the potatoes. The experiment showed that irradiation could appropriately extend the storage time of potatoes, and gamma irradiation of about 1000 Gy could achieve the best preservation effect. The main pathogenic fungi that cause dry rot of potatoes were Fusarium solani and Fusarium oxysporum, and the appropriate dose of 60Co-γ irradiation could effectively inhibit the spread and growth of these fungi.

Effects of low-temperature plasma, microwave and 60Co γ-irradiation treatments on the flavor characteristics of lychee whole fruit powder

Powdering whole lychee fruit is one of the most effective methods for improving the comprehensive utilization rate of lychees. In this study, lychee whole fruit powder (LWFP) was prepared and treated with low-temperature plasma, microwave, and 60Co γ-irradiation treatments to enhance its quality. Volatile organic compounds (VOCs) were analyzed using Headspace Solid Phase Micro-extraction Gas Chromatography-mass Spectrometry (HS-SPME-GC-MS), Headspace Gas Chromatography Ion Mobility Spectrometry (HS-GC-IMS), and electronic nose (E-nose) techniques. Electronic tongue (E-tongue) analysis revealed that both sweetness and bitterness were significant taste indicators of LWFP. GC-MS analysis revealed that the predominant volatile compounds in LWFP were terpenoids and alcohols, specifically nerol, geraniol, ɑ-pinene, hexylbenzene, ɑ-caryophyllene, caryophyllene oxide, and isoamylenol. GC-IMS identified small-molecule aldehydes such as 2-methyl propanal, hexanal, propanal, and 2-methylbutanal as significant contributors to the aroma profile. Moreover, key aromatic contributors include dimethyl sulfide, 1-penten-3-one, and acetic acid. Notably, microwave treatment exerted the most significant effect on the aroma profile of lychee. In contrast, low-temperature plasma and irradiation treatments exhibited similar and consistent changes. Specifically, microwave treatment primarily increased the concentration of larger terpenoid molecules such as nerol, 1-phenylhexane, and caryophyllene oxide, whereas low-temperature plasma and irradiation had a greater impact on smaller aldehyde molecules such as hexanal and 2-methylbutanal. All treatments enriched the sweet fruity, brilliant woody, and cabbage scents of LWFP.

Multilevel systemic engineering of Bacillus licheniformis for efficient production of acetoin from lignocellulosic hydrolysates

Bio-refining lignocellulosic resource offers a renewable and sustainable approach for producing biofuels and biochemicals. However, the conversion efficiency of lignocellulosic resource is still challenging due to the intrinsic inefficiency in co-utilization of xylose and glucose. In this study, the industrial bacterium Bacillus licheniformis was engineered for biorefining lignocellulosic resource to produce acetoin. First, adaptive evolution was conducted to improve acetoin tolerance, leading to a 19.6 % increase in acetoin production. Then, ARTP mutagenesis and 60Co-γ irradiation was carried out to enhance the production of acetoin, obtaining 73.0 g/L acetoin from glucose. Further, xylose uptake and xylose utilization pathway were rewired to facilitate the co-utilization of xylose and glucose, enabling the production of 60.6 g/L acetoin from glucose and xylose mixtures. Finally, this efficient cell factory was utilized for acetoin production from lignocellulosic hydrolysates with the highest titer of 68.3 g/L in fed-batch fermentation. This strategy described here holds great applied potential in the biorefinery of lignocellulose for the efficient synthesis of high-value chemicals.

Effects of Irradiation on the Major Components of Panax Notoginseng (Sanqi) Herbal Medicine

This paper investigates the effects of irradiation technology on the major components of Panax Notoginseng (Sanqi) herbal medicine. Irradiation technology, particularly 60Co-γ irradiation, has been widely used as an effective sterilization method in food and pharmaceutical processing. In the field of traditional Chinese medicine (TCM), irradiation technology has demonstrated unique advantages, effectively eliminating microbial contamination while preserving the main components and therapeutic efficacy of TCM. This paper first introduces the basic principles of irradiation technology and its current research status in TCM processing, then analyzes the major components and pharmacological effects of Panax Notoginseng, and finally assesses the impact of irradiation on these components, emphasizing its effectiveness and safety in maintaining medicinal efficacy.

Effects of radiation mitigating amino acid mixture on mice of different sexes.

To date, few FDA-approved medical countermeasures are available for addressing hematopoietic acute radiation syndrome (H-ARS). In this study, we present our latest research findings focusing on the evaluation of a novel radiation mitigator known as the mitigating amino acid mixture (MAAM). MAAM is composed of five amino acids as the recently reported amino acid-based oral rehydration solution for mitigating gastrointestinal (GI)-ARS. CD2F1 male and female mice were exposed to 60Co-γ total body irradiation (TBI) at 9.0 or 9.5 Gy. Following irradiation, mice were orally administered with MAAM or a saline vehicle control once daily for a duration of 14 days, commencing 24 h after TBI. Mouse survival and body weight change were monitored for 30 days after irradiation. Complete blood counts (CBCs), bone marrow (BM) stem and progenitor cell survival (clonogenicity), and a serum cytokine antibody array were analyzed using samples from day 30 surviving mice. Our data revealed that MAAM treatment significantly enhanced survival rates in irradiated male CD2F1 mice, and the survival rate increased from 25% in the vehicle control group to 60% in the MAAM-treated group (p < 0.05) after 9.0 Gy TBI. The number of BM colonies significantly increased from 41.8 ± 6.4 /104 cells (in the vehicle group) to 78.5 ± 17.0 /104 cells (in the MAAM group) following 9.0 Gy TBI. Furthermore, MAAM treatment led to a decrease in the levels of six cytokines/proteins [cluster of differentiation 40 (CD40), interleukin (IL)-17A, C-X-C motif chemokine 10 (CXCL10/CRG-2), cutaneous T cell-attracting chemokine (CTACK), macrophage inflammatory protein (MIP)-3β, and IL-1β] and an increase in the levels of five other cytokines/proteins [IL-3Rβ, IL-5, leptin, IL-6, and stem cell factor (SCF)] in mouse serum compared to the vehicle group after 9.0 Gy TBI. However, similar alleviating effects of MAAM were not observed in the irradiated CD2F1 female mice. The serum cytokine profile in the irradiated female mice was different compared to the irradiated male mice. In summary, our data suggest that the beneficial effects of the mitigative amino acid combination treatment after radiation exposure may depend on sex.

DNA binding, potential anticancer, antioxidant and molecular docking simulations of some isonicotinohydrazide metal complexes with the impact of high energy γ-rays irradiation doses: Synthesis and structural characterization

This work focuses on the preparation and characterization of some VO(II), Co(II), Cu(II), Zn(II) and Hg(II) complexes (1–5) of N'-(2-aminobenzoyl)isonicotinohydrazide ligand (HL). The compounds were characterized using various analytical and spectral tools. The resulting powder samples of the as prepared complexes (3,5) were exposed to two gamma ray doses up to 150 and 200 kGy from highly-energetic 60Co γ-irradiation (hereafter referred to as (3F,5F) at dose value of 150 kGy and (3F*,5F*) at dose value of 200 kGy). The impact of γ-irradiation on the possible structural changes of these samples after gamma irradiation was studied. The ligand and as prepared Cu(II) (3), Hg(II) (5) and their γ-irradiated (3F,5F) and (3F*,5F*) samples were tested for free radical scavenging activity using the DPPH assay. The DNA cleavage activity using supercoiled plasmid DNA (calf thymus ct-DNA) was explored. The tested ligand (HL) and complexes (3,5) showed excellent DNA binding. Additionally, the in vitro antitumor activity of (HL) and its Cu(II) (3) and Hg(II) (5) complexes was scrutinized against the human breast carcinoma (MCF-7), human hepatocarcinoma (Hep-G2) cell lines and kidney epithelial normal cells extracted from African green monkey kidney (Vero) to investigate the potential safety towards the normal cells. Also, docking simulation was done on the active site of 4FM9 and 1H7K protein for liver cancer and breast cancer cell line, respectively and showed excellent results.

Effects of 60Co γ-irradiation treatment on the diversity of fungal microflora in blueberries during cold storage

In the present study, the effects of 60Co-γ irradiation on the diversity of fungal microflora in blueberries during cold storage have been explored in detail. The effects of irradiation on the fungal microflora in blueberries could be observed at the lowest effective dose of 1.0 kGy. The genome library of fungal microflora in blueberries was evaluated by tusing Shannon, Simpson, Chao1, and ACE indices, presenting good coverage of blueberry samples. Principal coordinate analysis clarified the differences in the evolution and clustering of fungi in blueberries under different irradiation levels. The composition and diversity of fungal microflora in blueberries treated with different doses of radiation exhibited significant differences under cold storage of 4°C. However, most of the fungi belonged to the Ascomycota at the phylum. The fungal microflora was relatively stable at the initial stage of cold storage, however, the diversity of fungal species in irradiated blueberries varied greatly in the middle stage around the 15th day. This comprehensive study provides deeper insight about the effects of irradiation on the evolution of fungal microflora in blueberries during cold storage. The findings of this study lay a good foundation for post-harvest storage and preservation of blueberries.

Physiological and transcriptional analyses reveal the resistance mechanisms of kiwifruit (Actinidia chinensis) mutant with enhanced heat tolerance

High temperature is an environmental stressor that severely threatens plant growth, development, and yield. In this study, we obtained a kiwifruit mutant (MT) of ‘Hongyang’ (WT) through 60Co-γ irradiation. The MT possessed different leaf morphology and displayed prominently elevated heat tolerance compared to the WT genotype. When exposure to heat stress, the MT plants exhibited stabler photosynthetic capacity and accumulated less reactive oxygen species, along with enhanced antioxidant capacity and higher expression levels of related genes in comparison with the WT plants. Moreover, global transcriptome profiling indicated that an induction in genes related to stress-responsive, phytohormone signaling, and transcriptional regulatory pathways, which might contribute to the upgrade of thermotolerance in the MT genotype. Collectively, the significantly enhanced thermotolerance of MT might be mainly attributed to profitable leaf structure variations, improved photosynthetic and antioxidant capacities, as well as extensive transcriptome reprogram. These findings would be insightful in elucidating the sophisticated mechanisms of kiwifruit response to heat stress, and suggest the MT holds great potential for future kiwifruit improvement with enhanced heat tolerance.

Development, identification, and utilization of wheat-tetraploid Thinopyrum elongatum 4EL translocation lines resistant to stripe rust.

The new stripe rust resistance gene Yr4EL in tetraploid Th. elongatum was identified and transferred into common wheat via 4EL translocation lines. Tetraploid Thinopyrum elongatum is a valuable genetic resource for improving the resistance of wheat to diseases such as stripe rust, powdery mildew, and Fusarium head blight. We previously reported that chromosome 4E of the 4E (4D) substitution line carries all-stage stripe rust resistance genes. To optimize the utility of these genes in wheat breeding programs, we developed translocation lines by inducing chromosomal structural changes through 60Co-γ irradiation and developing monosomic substitution lines. In total, 53 plants with different 4E chromosomal structural changes were identified. Three homozygous translocation lines (T4DS·4EL, T5AL·4EL, and T3BL·4EL) and an addition translocation line (T5DS·4EL) were confirmed by the genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), FISH-painting, and wheat 55K SNP array analyses. These four translocation lines, which contained chromosome arm 4EL, exhibited high stripe rust resistance. Thus, a resistance gene (tentatively named Yr4EL) was localized to the chromosome arm 4EL of tetraploid Th. elongatum. For the application of marker-assisted selection (MAS), 32 simple sequence repeat (SSR) markers were developed, showing specific amplification on the chromosome arm 4EL and co-segregation with Yr4EL. Furthermore, the 4DS·4EL line could be selected as a good pre-breeding line that better agronomic traits than other translocation lines. We transferred Yr4EL into three wheat cultivars SM482, CM42, and SM51, and their progenies were all resistant to stripe rust, which can be used in future wheat resistance breeding programs.

Ciprofloxacin and pegylated G-CSF combined therapy mitigates brain hemorrhage and mortality induced by ionizing irradiation.

Brain hemorrhage was found between 13 and 16 days after acute whole-body 9.5 Gy 60Co-γ irradiation (IR). This study tested countermeasures mitigating brain hemorrhage and increasing survival from IR. Previously, we found that pegylated G-CSF therapy (PEG) (i.e., Neulasta®, an FDA-approved drug) improved survival post-IR by 20-40%. This study investigated whether Ciprofloxacin (CIP) could enhance PEG-induced survival and whether IR-induced brain hemorrhage could be mitigated by PEG alone or combined with CIP. B6D2F1 female mice were exposed to 60Co-γ-radiation. CIP was fed to mice for 21 days. PEG was injected on days 1, 8, and 15. 30-day survival and weight loss were studied in mice treated with vehicles, CIP, PEG, or PEG + CIP. For the early time point study, blood and sternums on days 2, 4, 9, and 15 and brains on day 15 post-IR were collected. Platelet numbers, brain hemorrhage, and histopathology were analyzed. The cerebellum/pons/medulla oblongata were detected with glial fibrillary acidic protein (GFAP), p53, p16, interleukin-18 (IL-18), ICAM1, Claudin 2, ZO-1, and complement protein 3 (C3). CIP + PEG enhanced survival after IR by 85% vs. the 30% improvement by PEG alone. IR depleted platelets, which was mitigated by PEG or CIP + PEG. Brain hemorrhage, both surface and intracranial, was observed, whereas the sham mice displayed no hemorrhage. CIP or CIP + PEG significantly mitigated brain hemorrhage. IR reduced GFAP levels that were recovered by CIP or CIP + PEG, but not by PEG alone. IR increased IL-18 levels on day 4 only, which was inhibited by CIP alone, PEG alone, or PEG + CIP. IR increased C3 on day 4 and day 15 and that coincided with the occurrence of brain hemorrhage on day 15. IR increased phosphorylated p53 and p53 levels, which was mitigated by CIP, PEG or PEG + CIP. P16, Claudin 2, and ZO-1 were not altered; ICAM1 was increased. CIP + PEG enhanced survival post-IR more than PEG alone. The Concurrence of brain hemorrhage, C3 increases and p53 activation post-IR suggests their involvement in the IR-induced brain impairment. CIP + PEG effectively mitigated the brain lesions, suggesting effectiveness of CIP + PEG therapy for treating the IR-induced brain hemorrhage by recovering GFAP and platelets and reducing C3 and p53.

Sensitivity investigation of 100-MeV proton irradiation to SiGe HBT single event effect

The single event effect (SEE) sensitivity of silicon–germanium heterojunction bipolar transistor (SiGe HBT) irradiated by 100-MeV proton is investigated. The simulation results indicate that the most sensitive position of the SiGe HBT device is the emitter center, where the protons pass through the larger collector-substrate (CS) junction. Furthermore, in this work the experimental studies are also carried out by using 100-MeV proton. In order to consider the influence of temperature on SEE, both simulation and experiment are conducted at a temperature of 93 K. At a cryogenic temperature, the carrier mobility increases, which leads to higher transient current peaks, but the duration of the current decreases significantly. Notably, at the same proton flux, there is only one single event transient (SET) that occurs at 93 K. Thus, the radiation hard ability of the device increases at cryogenic temperatures. The simulation results are found to be qualitatively consistent with the experimental results of 100-MeV protons. To further evaluate the tolerance of the device, the influence of proton on SiGe HBT after gamma-ray (60Coγ) irradiation is investigated. As a result, as the cumulative dose increases, the introduction of traps results in a significant reduction in both the peak value and duration of the transient currents.

LHD3 Encoding a J-Domain Protein Controls Heading Date in Rice

Heading date is one of the most important agronomic traits of rice, which critically affects rice ecogeographical adaptation, yield and quality. In this study, a late heading date 3 (lhd3) mutant was screened from the 60Co-γ irradiation mutant library. The lhd3 delayed heading date in rice under both short day and long day conditions. Map-based cloning combined with Mutmap strategy was adopted to isolate the causal LHD3 gene. The LHD3 gene encodes a DNA_J domain protein, which was ubiquitously expressed in various plant organs, and dominant expressed in stems and leaves. Subcellular localization analysis showed that LHD3 was localized to nucleus, indicating that LHD3 may interact with other elements to regulate the expression of flowering genes. The transcriptions of the heading activators Ehd1, Hd3a and RFT1 significantly decreased in the lhd3 mutant, suggesting that LHD3 may control the heading date through the Ehd1-Hd3a/RFT1 photoperiodic flowering pathway. The variation and haplotype analyses of the genomic region of LHD3 showed that there were 7 haplotypes in the LHD3 region from 4 702 accessions. The haplotypes of LHD3 can be divided into two classes: class a and class b, and the heading dates of these two classes were significantly different. Further study showed that two single nucleotide polymorphisms (SNPs), SNP10 (G2100C) in Hap II and SNP3 (C861T) in Hap VII, may be the functional sites causing early and late heading in accessions. Nucleotide diversity analysis showed LHD3 had been selected in the indica population, rather than in the japonica population. Therefore, the present study sheds light on the regulation of LHD3 on heading date in rice and suggests that LHD3 is a novel promising new target for rice molecular design and breeding improvement.

The impact of irradiation on ginsenoside variations in red ginseng and its hypoglycemic effects in type 1 diabetic mice

This study aimed to investigate the impact of irradiation on the saponin content in red ginseng extract (ISERG) and its hypoglycemic effects using high-performance liquid chromatography and in vivo experiments. The results revealed a significant increase in the levels of red ginseng ginsenosides Rh4 and CK by 75.56% and 59.32% respectively after exposure to 15 kGy 60Co-γ irradiation. Furthermore, the administration of 500 mg/kg·BW 15 kGy 60Co-γ irradiated ISERG for 32 days demonstrated notable reductions in blood sugar levels and increased insulin levels in Type 1 Diabetes Mellitus (T1DM) mice. Moreover, it effectively improved glucose and lipid metabolism, organ coefficient, and antioxidant related indicators in T1DM mice. The study also observed improvements in the expression levels of InsR, IRS1, and Sirt6 proteins, suggesting their potential in diabetes treatment. These findings highlight the promising application of irradiated red ginseng in the future.

Influence of 60Co-γ Irradiation on the Components of Essential Oil of Curcuma.

The gas chromatography-ion mobility spectrometry (GC-IMS) method is a new technology for detecting volatile organic compounds. This study was carried out to evaluate the effects of volatile aroma compounds of Curcuma essential oils (EOs) after 60Co radiation by GC-IMS. Dosages of 0, 5, and 10 kGy of 60Co were used to analyze EOs of Curcuma after 60Co irradiation (named EZ-1, EZ-2, and EZ-3). The odor fingerprints of volatile organic compounds in different EOs of Curcuma samples were constructed by headspace solid-phase microextraction and GC-IMS after irradiation. The differences in odor fingerprints of EOs were compared by principal component analysis (PCA). A total of 92 compounds were detected and 65 compounds were identified, most of which were ketones, aldehydes, esters, and a small portion were furan compounds. It was found that the volatile matter content of 0 kGy and 5 kGy was closer, and the use of 10 kGy 60Co irradiation would have an unstable effect on the EOs. In summary, it is not advisable to use a higher dose when using 60Co irradiation for sterilization of Curcuma. Due to the small gradient of irradiation dose used in the experiment, the irradiation dose can be adjusted appropriately according to the required sterilization requirements during the production and storage process of Curcuma to obtain the best irradiation conditions. GC-IMS has the advantages of GC's high separation capability and IMS's fast response, high resolution, and high sensitivity, and the sample requires almost no pretreatment; it can be widely used in the analysis of traditional Chinese medicines containing volatile components. It is shown that irradiation technology has good application prospects in the sterilization of traditional Chinese medicines, but the changes in irradiation dose and chemical composition must be paid attention to.

Biological effect of gamma and electron beam to target turning X-ray irradiation on two varieties of freesia in M3 generation

The study was carried out to explore the effects of 60Co-γ irradiation and electron beam to target turning X-ray (EBTTX) irradiation in the M3 generation to accelerate the breeding process of freesia. Bulbs of two varieties of freesia “Freesia armstrongii W. Watson” and “Freesia corymbosa (Burm.f.) N. E. Br” were exposed to 4 doses of 60Co-γ and EBTTX irradiation (25, 50, 75, and 100 Gy). The stimulatory effect on germination rate, survival rate, plant height, leaf number, leaf area, root number, root length, flowering plant rate, and pedicel length of two freesia cultivars at 25 Gy of 60Co-γ irradiation dose was better than EBTTX in M3 generation. High irradiation dose exhibited stronger inhibitory effects on these plants' growth parameters and even the survival rate of two freesia cultivars was 0.00% at 100 Gy irradiation dose for both types of irradiation. The total chlorophyll content of freesia “Freesia armstrongii W. Watson” and “Freesia corymbosa (Burm.f.) N. E. Br” reached the maximum under the radiation dose of 25 Gy. With the increase in radiation dose, the content of MDA, SOD, and POD in the leaves of both varieties of freesia increased gradually. In the M3 generation of the two freesia varieties, five new mutant plants such as dwarf plants, altered flower color, and increased petal numbers were found. A high frequency of mean mutations was found in EBTTX irradiated plants (4.16% and 3.3%) than in gamma-irradiated plants (2.4% and 2.5%) at 50 Gy as compared with control in Freesia armstrongii W. Watson and Freesia corymbosa (Burm.f.) N. E. Br.

60Co γ-irradiation of AlGaN UVC light-emitting diodes

270 nm AlGaN UV Light-Emitting Diodes (LEDs) were exposed to 1–5 Mrad fluences of Co-60 γ-rays. The effect of the exposure to radiation was a ∼40% reduction in optical output after the highest fluence. No significant midgap emission was induced in the electro-luminescence spectra of the irradiated LEDs. We ascribe the decrease in optical output to creation of non-radiative states within the active regions. There were small (5–10%) increases in forward and reverse current as a result of irradiation with an effective carrier removal rate of <1 cm−1. The irradiation did not produce any increase in degradation rate of the LEDs output power under high drive current (95 mA) compared to unirradiated devices, which is consistent with the lack of midgap emission. The relatively small changes in electrical and optical properties, along with the resistance of the AlxGa1-xN/AlN to displacement damage effects indicate these devices may be well-suited to harsh terrestrial and space radiation applications.

Modeling of scavenging systems in water radiolysis with Geant4-DNA

PurposeThis paper presents the capabilities of the Geant4-DNA Monte Carlo toolkit to simulate water radiolysis with scavengers using the step-by-step (SBS) or the independent reaction times (IRT) methods. It features two examples of application areas: (1) computing the escape yield of H2O2 following a 60Co γ-irradiation and (2) computing the oxygen depletion in water irradiated with 1 MeV electrons. MethodsTo ease the implementation of the chemical stage in Geant4-DNA, we developed a user interface that helps define the chemical reactions and set the concentration of scavengers. The first application area example required two computational steps to perform water radiolysis using NO2- and NO3- as scavengers and a 60Co irradiation. The oxygen depletion computation technique for the second application area example consisted of simulating track segments of 1 MeV electrons and determining the radio-induced loss and gain of oxygen molecules. ResultsThe production of H2O2 under variable scavenging levels is consistent with the literature; the mean relative difference between the SBS and IRT methods is 7.2 % ± 0.5 %. For the oxygen depletion 1 µs post-irradiation, the mean relative difference between both methods is equal to 9.8 % ± 0.3 %. The results in the microsecond scale depend on the initial partial pressure of oxygen in water. In addition, the computed oxygen depletions agree well with the literature. ConclusionsThe Geant4-DNA toolkit makes it possible to simulate water radiolysis in the presence of scavengers. This feature offers perspectives in radiobiology, with the possibility of simulating cell-relevant scavenging mechanisms.

Suitable doses screening for mutagenesis in Phytoseiulus persimilis induced by &lt;sup&gt;60&lt;/sup&gt;Co-γ

Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) is a specialist predator of Tetranychus sp.; however, the lack of resistance to high temperatures and drought may result in the lower biological control efficiency of P. persimilis in the adverse climatic conditions. In breeding programs, 60Co-γ irradiation is commonly used to quickly screen suitable mutants, optimize biological characteristics, and improve resistance. It is expected that 60Co-γ irradiation could be useful in resistance screening in P. persimilis. The purpose of this study is to determine the suitable doses of 60Co-γ with high levels of mutagenesis in P. persimilis. P. persimilis individuals were irradiated using 60Co-γ at 0, 20, 40, 60, 70, 75, 80, 85, 90, 95, 100, 200, 300, and 400 Gy, with a dose rate of 0.5 Gy/min. The mortality of irradiated individuals was used to estimate the LD50. The fecundity of survived individuals and egg hatch rate were applied to estimate the mutagenesis frequency. The mortality of P. persimilis increased with increasing irradiation dose with a rapid increase between 70 to 95 Gy. When irradiation dose exceeded 100 Gy, almost all P. persimilis died. The LD50 of irradiation dose was ca. 80 Gy. When irradiation doses increased from 70 to 95 Gy, sterility rate increased from 5% to 20%, fecundity decreased from 97% to 80%, and egg hatch rate decreased from 98% to 60%. We suggest that the appropriate irradiation doses of 60Co-γ inducing higher P. persimilis mutagenesis were between 70 Gy and 95 Gy. Results of this study allow future large-scale screening for resistant strains of P. persimilis.

Changes in the microbiota of a vacuum-packed cooked bass product and the effects of cobalt irradiation on its quality during storage

This study investigates changes in the microbiota of vacuum-packed cooked bass (Micropterus salmoides), including the effects of different doses of 60Co-γ irradiation (0, 1, 3, and 5 kGy) on muscle quality, during storage at 4 °C (0–15 days). Analyses for other indicators like the total bacterial colony counts and myofibrillar protein concentration were carried out. 16SrDNA high-throughput sequencing results showed that Stenotrophomonas maltophilia had the highest relative abundance in bass after storage. Additionally, the total bacterial colony counts and total volatile basic nitrogen (TVB-N) content of the irradiated samples were within the standard limits after day 15. During 0–6 days of storage, 3 kGy irradiation increased the myofibrillar protein concentration and the water-holding capacity of the fish compared with other doses. However, 3 kGy irradiation had less influence on the surface hydrophobicity of myofibrillar proteins than 5 kGy irradiation. Overall, Stenotrophomonas maltophilia was the dominant spoilage bacteria in bass, and 3 kGy irradiation treatment effectively inhibited microbial proliferation and muscle quality deterioration during storage at 4 °C. Moreover, the optimal storage time for bass products after 3 kGy irradiation treatment was 6 days. This provides a basis for improving bass quality during storage and promoting the application of irradiation technology.