Genetic Variability Studies in M5 Generations of Determinate Early Maturing Cluster Bean [Cyamopsis tetragonoloba (L.) Taub] (MDU-1) Mutants for Yield and Yield Attributing Characters

Background: MDU-1 is a high yielding, indeterminate cluster bean variety. In order to develop determinate mutant with high yield, MDU-1 cluster bean variety was irradiated using gamma rays, electron beam and combination of gamma rays and EMS with different doses and the variability induced in M5 generations were studied. Methods: Twenty one best individual plants from M4 generation were selected based on plant height and higher yield and forwarded to M5 generation where they were evaluated in RBD with three replications. Fourteen non-segregating mutant lines with desirable traits were identified in M5 generation and were evaluated for variability along with the parent MDU1. Result: Five best mutant lines namely ACMC-020-04, ACMC-020-11, ACMC-020-08, ACMC-020-10 and ACMC-020-11 were selected from the 14 accessions based on per se performance and variability analysis. The selected mutants needs to be forwarded for stability testing in different environments.

Dose-dependent Transmissibility of Chromosome Aberrations at First Mitosis after Exposure to Gamma Rays. I. Modeling and Implications Related to Risk Assessment

The relationship between certain chromosomal aberration (CA) types and cell lethality is well established. On that basis we used multi-fluor in situ hybridization (mFISH) to tally the number of mitotic human lymphocytes exposed to graded doses of gamma rays that carried either lethal or nonlethal CA types. Despite the fact that a number of nonlethal complex exchanges were observed, the cells containing them were seldom deemed viable, due to coincident lethal chromosome damage. We considered two model variants for describing the dose responses. The first assumes independent linear-quadratic (LQ) dose response shapes for the yields of both lethal and nonlethal CAs. The second (simplified) variant assumes that the mean number of nonlethal CAs per cell is proportional to the mean number of lethal CAs per cell, meaning that the shapes and magnitudes of both aberration types differ only by a multiplicative proportionality constant. Using these models allowed us to assemble dose response curves for the frequency of aberration-bearing cells that would be expected to survive. This took the form of a joint probability distribution for cells containing ≥1 nonlethal CAs but having zero lethal CAs. The simplified second model variant turned out to be marginally better supported than the first, and the joint probability distribution based on this model yielded a crescent-shaped dose response reminiscent of those observed for mutagenesis and transformation for cells “at risk” (i.e. not corrected for survival). Among the implications of these findings is the suggestion that similarly shaped curves form the basis for deriving metrics associated with radiation risk models.

Imaging and sensing of pH and chemical state with nuclear-spin-correlated cascade gamma rays via radioactive tracer

Single-photon-emission computed tomography (SPECT) and positron-emission tomography (PET) are highly sensitive molecular detection and imaging techniques that generally measure accumulation of radio-labeled molecules by detecting gamma rays. Quantum sensing of local molecular environment via spin, such as nitrogen vacancy (NV) centers, has also been reported. Here, we describe quantum sensing and imaging using nuclear-spin time-space correlated cascade gamma-rays via a radioactive tracer. Indium-111 (111In) is widely used in SPECT to detect accumulation using a single gamma-ray photon. The time-space distribution of two successive cascade gamma-rays emitted from an 111In atom carries significant information on the chemical and physical state surrounding molecules with double photon coincidence detection. We propose and demonstrate quantum sensing capability of local micro-environment (pH and chelating molecule) in solution along with radioactive tracer accumulation imaging, by using multiple gamma-rays time-and-energy detection. Local molecular environment is extracted through electric quadrupole hyperfine interaction in the intermediate nuclear spin state by the explicit distribution of sub-MeV gamma rays. This work demonstrates a proof of concept, and further work is necessary to increase the sensitivity of the technique for in vivo imaging and to study the effect of scattered radiation for possible application in nuclear medicine.

Application of a tungsten apron for occupational radiation exposure in nursing care of children with neuroblastoma during 131I-meta-iodo-benzyl-guanidine therapy

The use of effective shielding materials against radiation is important among medical staff in nuclear medicine. Hence, the current study investigated the shielding effects of a commercially available tungsten apron using gamma ray measuring instruments. Further, the occupational radiation exposure of nurses during 131I-meta-iodo-benzyl-guanidine (131I-MIBG) therapy for children with high-risk neuroblastoma was evaluated. Attachable tungsten shields in commercial tungsten aprons were set on a surface-ray source with 131I, which emit gamma rays. The mean shielding rate value was 0.1 ± 0.006 for 131I. The shielding effects of tungsten and lead aprons were evaluated using a scintillation detector. The shielding effect rates of lead and tungsten aprons against 131I was 6.3% ± 0.3% and 42.1% ± 0.2% at 50 cm; 6.1% ± 0.5% and 43.3% ± 0.3% at 1 m; and 6.4% ± 0.9% and 42.6% ± 0.6% at 2 m, respectively. Next, we assessed the occupational radiation exposure during 131I-MIBG therapy (administration dose: 666 MBq/kg, median age: 4 years). The total occupational radiation exposure dose per patient care per 131I-MIBG therapy session among nurses was 0.12 ± 0.07 mSv. The average daily radiation exposure dose per patient care among nurses was 0.03 ± 0.03 mSv. Tungsten aprons had efficient shielding effects against gamma rays and would be beneficial to reduce radiation exposures per patient care per 131I-MIBG therapy session.

Frequency and Spectrum of Mutations Induced by Gamma Rays Revealed by Phenotype Screening and Whole-Genome Re-Sequencing in Arabidopsis thaliana

Genetic variations are an important source of germplasm diversity, as it provides an allele resource that contributes to the development of new traits for plant breeding. Gamma rays have been widely used as a physical agent for mutation creation in plants, and their mutagenic effect has attracted extensive attention. However, few studies are available on the comprehensive mutation profile at both the large-scale phenotype mutation screening and whole-genome mutation scanning. In this study, biological effects on M1 generation, large-scale phenotype screening in M2 generation, as well as whole-genome re-sequencing of seven M3 phenotype-visible lines were carried out to comprehensively evaluate the mutagenic effects of gamma rays on Arabidopsis thaliana. A total of 417 plants with visible mutated phenotypes were isolated from 20,502 M2 plants, and the phenotypic mutation frequency of gamma rays was 2.03% in Arabidopsis thaliana. On average, there were 21.57 single-base substitutions (SBSs) and 11.57 small insertions and deletions (InDels) in each line. Single-base InDels accounts for 66.7% of the small InDels. The genomic mutation frequency was 2.78 × 10−10/bp/Gy. The ratio of transition/transversion was 1.60, and 64.28% of the C > T events exhibited the pyrimidine dinucleotide sequence; 69.14% of the small InDels were located in the sequence with 1 to 4 bp terminal microhomology that was used for DNA end rejoining, while SBSs were less dependent on terminal microhomology. Nine genes, on average, were predicted to suffer from functional alteration in each re-sequenced line. This indicated that a suitable mutation gene density was an advantage of gamma rays when trying to improve elite materials for one certain or a few traits. These results will aid the full understanding of the mutagenic effects and mechanisms of gamma rays and provide a basis for suitable mutagen selection and parameter design, which can further facilitate the development of more controlled mutagenesis methods for plant mutation breeding.

​Binasoybean-6: A High Yielding Mutant Soybean Variety Developed through Sustainable Mutation Breeding

Background: Soybean is an important source of food, protein and oil and hence more research is essential to increase its yield under different agro-ecological conditions, including stress. In this regard, four popular soybean varieties viz. Shohag, BDS-4, BAU-S/64 and BARI Soybean-5 were irradiated using Co60 gamma rays to create genetic variation for earliness, higher seed yield and other desirable agronomic traits. Methods: The experiments were conducted at Bangladesh Institute of Nuclear Agriculture (BINA) Headquarters farm, Mymensingh during 2006-2009 and 28 elite mutant lines were selected for evaluation. The mutant line, SBM-22 derived from mother variety BARI Soybean-5 irradiated with 300Gy of gamma rays was found to be superior compared to other mutants. Considering the superior performance of mutant SBM-22 including 28 mutants and mother check variety BARI Soybean-5, were evaluated through different trials. The evaluation trials were conducted at different agro-ecological zones of the country during Rabi season (January to April) of 2010-2018. Result: Significant variations were observed both in individual location and over locations for all traits. Reactions to major diseases and insect-pests infestation were also studied. Due to better performance of the mutant SBM-22, Bangladesh Institute of Nuclear Agriculture (BINA) applied to the National Seed Board (NSB) of Bangladesh for registration as an important soybean variety “Binasoybean-6”. Consequently, the NSB of Bangladesh registered SBM-22 as an improved soybean variety in 2019 as Binasoybean-6 for commercial cultivation.

The effect of Co-60 gamma rays irradiation on chemical properties of biofertilizer carrier material

This study was conducted to test the method of sterilization using autoclave and Co-60 gamma rays irradiation on chemical properties changes of biofertilizer carriers (Jasinga Latosols, Pasar Jumat Latosols, compost, Rawa Pening peat, Kalimantan peat). This research was conducted in July 2016 to April 2017 at Center for the Application of Isotopes and Radiation National Nuclear Energy Agency (PAIR BATAN) laboratory and Ilmu Tanah Sumber Daya Lahan Insitut Pertanian Bogor (IPB) laboratory. The design used in this study is completely randomized design, with seven treatment and five replications. The treatments provided include the control (without sterilization), sterilization using autoclave, and sterilization using gamma ray of Co-60 with doses of 10 kilo Gray (kGy), 20 kGy, 30 kGy, 40 kGy and 50 kGy. The parameters observed in this research was available Mn2+, available Fe2+, available Zn2+, and effectiveness of sterilization method. This research also showed chemical character changes in materials as shown by Fouier-Transform Infrared Spectrometer (FTIR) spectra. The results showed that the methods sterilization was gave significant effect on pH changes, the levels of available P, the levels of available nitrates, available Mn2+, available Fe2+, and available Zn2+. Autoclave has led to a higher metal increase compared to Co-60 gamma irradiation. A dose of 30 kGy is an effective dose to sterilize the carriers material.

Seleksi Mutan Tanaman Lamtoro (Leucaena leucocephala cv. Tarramba) Tahan Kutu Loncat terhadap Lingkungan Kering pada Rumah Kaca

Forage is the main source of feed for ruminants. Forage consists of two types, namely grass and legumes. Leguminosa is a type of forage as a source of protein. One type of legume that is well known by breeders in Indonesia is lamtoro (Leucaena leucocephala cv. Tarramba). This study was aimed to produce candidate mutants of lamtoro drought resistant to acid stress conditions. The experiment in this study used an unbalanced completely randomized design with 6 treatments of 740 different replications based on different sources of lamtoro plant mutants at different levels (P0: 0 n= 89, P1: 100 gy n= 82, P2: 200 gy n= 153, P3:300 gy n=120, P4: 400 gy n= 244, P5: 500 gy n= 52). Variables observed included plant height, number of stalks, leaf loss and stem diameter. The results showed that lamtoro plants irradiated with gamma rays at a level of 200 gy-500 gy were significantly higher than 100 gy irradiation at 10 and 12 days watering, but the diameter of the plants was larger at 100 gy irradiation. It can be watering intervals of 10 days and 12 days on the parameters of height and stem diameter showed that gamma rays irradiation of 400 gy resulted in dry-resistant lamtoro mutant candidates under acid stress condition. Key words: gamma rays, lamtoro mutant, watering interval