WorldWideScience

Sample records for radiation-induced mutation rate

  1. Radiation-induced cell mutations as a function of dose rate

    International Nuclear Information System (INIS)

    Kiefer, J.

    1987-01-01

    A brief review of the data in the literature is presented and forms the background of the experimental data given by the author obtained with exponential long-term cultures of V79 hamster cells exposed over a period of up to 35 days to different dose rates of gamma radiation. The experimental results show that at a dose rate of 40 mGy/hour the number of induced mutations is reduced, - which is in agreement with literature data - , but a dose rate of less than 30 mGy/hour makes the induced mutations leap to a value clearly higher than those induced by acute irradiation. As in addition to the mutations recombination is a significant factor of the radiation risk, experiments with a heterozygotic yeast strain have been made, as there is to date no reliable mammalian cell system available for this kind of research. Long-term radiation exposure of the yeast cells over a period of six weeks drastically increased the rate of recombinations, to a value higher by a factor of about 4 than that induced by acute irradiation. (orig.) [de

  2. Radiation-induced mutation at minisatellite loci

    International Nuclear Information System (INIS)

    Dubrova, Y.E.; Nesterov, V.N.; Krouchinsky, N.G.

    1997-01-01

    We are studying the radiation-induced increase of mutation rate in minisatellite loci in mice and humans. Minisatellite mutations were scored by multilocus DNA fingerprint analysis in the progeny of γ-irradiated and non-irradiated mice. The frequency of mutation in offspring of irradiated males was 1.7 higher that in the control group. Germline mutation at human minisatellite loci was studied among children born in heavily polluted areas of the Mogilev district of Belarus after the Chernobyl accident and in a control population. The frequency of mutation assayed both by DNA fingerprinting and by eight single locus probes was found to be two times higher in the exposed families than in the control group. Furthermore, mutation rate was correlated with the parental radiation dose for chronic exposure 137 Cs, consistent with radiation-induction of germline mutation. The potential use of minisatellites in monitoring germline mutation in humans will be discussed

  3. Radiation-induced mutations in mammals

    International Nuclear Information System (INIS)

    Ehling, U.H.

    1993-01-01

    The aims of the proposed project are to provide a better basis for extrapolation of animal data to man. Genetic endpoint, strain and species comparisons are made, which will provide critical experimental data regarding strategies in extrapolating laboratory animal data to man. Experiments were conducted to systematically compare the spontaneous and radiation-induced mutation rates for recessive specific-locus, dominant cataract and enzyme activity alleles in the mouse as well as a comparison of the mutation rate in the mouse and hamster for dominant cataract and enzyme activity alleles. The comparison of the radiation-dose response for recessive specific-locus and dominant cataract mutations are extended. Selected mutations are characterized at the genetic, biochemical and molecular levels. (R.P.) 5 refs., 3 tabs

  4. Radiation-induced mutations and plant breeding

    International Nuclear Information System (INIS)

    Naqvi, S.H.M.

    1985-01-01

    Ionizing radiation could cause genetic changes in an organism and could modify gene linkages. The induction of mutation through radiation is random and the probability of getting the desired genetic change is low but can be increased by manipulating different parameters such as dose rate, physical conditions under which the material has been irradiated, etc. Induced mutations have been used as a supplement to conventional plant breeding, particularly for creating genetic variability for specific characters such as improved plant structure, pest and disease resistance, and desired changes in maturity period; more than 200 varieties of crop plants have been developed by this technique. The Pakistan Atomic Energy Commission has used this technique fruitfully to evolve better germplasm in cotton, rice, chickpea, wheat and mungbean; some of the mutants have become popular commercial varieties. This paper describes some uses of radiation induced mutations and the results achieved in Pakistan so far

  5. Understanding the role of p53 in adaptive response to radiation-induced germline mutations

    International Nuclear Information System (INIS)

    Langlois, N.L.; Quinn, J.S.; Somers, C.M.; Boreham, D.R.; Mitchel, R.E.J.

    2003-01-01

    Full text: Radiation-induced adaptive response is now a widely studied area of radiation biology. Studies have demonstrated reduced levels of radiation-induced biological damage when an 'adaptive dose' is given before a higher 'challenge dose' compared to when the challenge dose is given alone. It has been shown in some systems to be a result of inducible cellular repair systems. The adaptive response has been clearly demonstrated in many model systems, however its impact on heritable effects in the mammalian germline has never been studied. Expanded Simple Tandem Repeat (ESTR) loci have been used as markers demonstrating that induced heritable mutations in mice follow a dose-response relationship. Recent data in our laboratory show preliminary evidence of radiation-induced adaptive response suppressing germline mutations at ESTR loci in wild type mice. The frequency of heritable mutations was significantly reduced when a priming dose of 0.1 Gy was given 24 hours prior to a 1 Gy acute challenging dose. We are now conducting a follow-up study to attempt to understand the mechanism of this adaptive response. P53 is known to play a significant role in governing apoptosis, DNA repair and cancer induction. In order to determine what function p53 has in the adaptive response for heritable mutations, we have mated radiation treated Trp53+/- male mice (C57Bl) to untreated, normal females (C57Bl). Using DNA fingerprinting, we are investigating the rate of inherited radiation-induced mutations on pre- and post-meiotic radiation-treated gametocytes by examining mutation frequencies in offspring DNA. If p53 is integral in the mechanism of adaptive response, we should not see an adaptive response in radiation-induced heritable mutations in these mice. This research is significant in that it will provide insight to understanding the mechanism behind radiation-induced adaptive response in the mammalian germline

  6. Gamma radiation-induced heritable mutations at repetitive DNA loci in out-bred mice

    International Nuclear Information System (INIS)

    Somers, C.M.; Sharma, R.; Quinn, J.S.; Boreham, D.R.

    2004-01-01

    Recent studies have shown that expanded-simple-tandem-repeat (ESTR) DNA loci are efficient genetic markers for detecting radiation-induced germ line mutations in mice. Dose responses following irradiation, however, have only been characterized in a small number of inbred mouse strains, and no studies have applied Esters to examine potential modifiers of radiation risk, such as adaptive response. We gamma-irradiated groups of male out-bred Swiss-Webster mice with single acute doses of 0.5 and 1.0 Gy, and compared germ line mutation rates at ESTR loci to a sham-irradiated control. To test for evidence of adaptive response we treated a third group with a total dose of 1.1 Gy that was fractionated into a 0.1 Gy adapting dose, followed by a challenge dose of 1.0 Gy 24 h later. Paternal mutation rates were significantly elevated above the control in the 0.5 Gy (2.8-fold) and 1.0 Gy (3.0-fold) groups, but were similar to each other despite the difference in radiation dose. The doubling dose for paternal mutation induction was 0.26 Gy (95% CI = 0.14-0.51 Gy). Males adapted with a 0.1 Gy dose prior to a 1.0 Gy challenge dose had mutation rates that were not significantly elevated above the control, and were 43% reduced compared to those receiving single doses. We conclude that pre-meiotic male germ cells in out-bred Swiss-Webster mice are sensitive to ESTR mutations induced by acute doses of ionizing radiation, but mutation induction may become saturated at a lower dose than in some strains of inbred mice. Reduced mutation rates in the adapted group provide intriguing evidence for suppression of ESTR mutations in the male germline through adaptive response. Repetitive DNA markers may be useful tools for exploration of biological factors affecting the probability of heritable mutations caused by low-dose ionizing radiation exposure. The biological significance of ESTR mutations in terms of radiation risk assessment, however, is still undetermined

  7. Radiation induced mutations for plant selection

    International Nuclear Information System (INIS)

    Brunner, H.

    1994-01-01

    The successful use of plant breeding for improving crops requires the existence of genetic variation of useful traits. Unfortunately, the desired variation is often lacking. However, radiation can be used to induce mutations and thereby generate genetic variation from which desired mutants may be selected. Mutation induction has become a proven way of creating variation within a crop variety. It offers the possibility of inducing desired attributes that either cannot be expressed in nature or have been lost during evolution. More than 1700 mutant cultivars of crop plants with significantly improved attributes such as increased yield, improved quality, disease and stress resistance, have been released worldwide in the last thirty years. The Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture has contributed to these achievements through the promotion of research and development in mutation breeding techniques using nuclear and related biotechnological methods and the provision of in plant breeding is then transferred to Member States of the IAEA and the FAO through training in mutation breeding methods and the provision of technical advice. Moreover, radiation treatment services are provided to foster applications of nuclear techniques in crop improvement programmes of member states and more specifically to render direct support to plant breeders by efficient generation of mutations. Plant materials are standardized prior to radiation exposure to warrant reproducibility of the induced effects within practical limits and a radiosensitivity test is implemented to affirm useful doses for applied objectives of a request. This review deals with irradiation methods applied at the IAEA laboratories for the efficient induction of mutations in seeds, vegetative propagules and tissue and cell cultures and the establishment of genetically variable populations upon which selection of desired traits can be based. 3 tabs., 18 refs. (author)

  8. Radiation-induced dominant skeletal mutations in mice

    International Nuclear Information System (INIS)

    Selby, P.B.

    1979-01-01

    Skeletons were chosen for the attempt to determine the overall damage by radiation to one body system largely bacause they can be prepared readily for detailed study. Dominant mutations were of special interest because they are the type of mutations that would account for almost all damage induced in the early generations. The male offsprings derived from spermatogonial irradiation were used in the mutation-rate experiment, and the mutation frequency of 1.4% per gamete was found. The general dominant skeletal mutations are 1) the fusions of bones or other changes in individual bones, 2) the gross changes in bone shapes, usually caused by incomplete or too extensive bone growth, or 3) the shifts in the relative positions of bones. The recessive lethality in the period between implantation and birth can be recognized by the expected high death rate of implants in approximately 1/4 of the crosses that are between heterozygotes for a given mutation. The recessive lethal mutations may account for an important fraction of human genetic disorders owing to their dominant deleterious effects which represent only a small fraction, but because of their easy detection, they have been studied more than other dominants. At least 45, or 27%, of 164 dominant visibles in mice, ignoring those concerned with enzyme polymorphisms and immunological traits, appear to be recessive lethals. (Yamashita, S.)

  9. Current study on ionizing radiation-induced mitochondial DNA damage and mutations

    International Nuclear Information System (INIS)

    Zhou Xin; Wang Zhenhua; Zhang Hong

    2012-01-01

    Current advance in ionizing radiation-induced mitochondrial DNA damage and mutations is reviewed, in addition with the essential differences between mtDNA and nDNA damage and mutations. To extent the knowledge about radiation induced mitochondrial alterations, the researchers in Institute of Modern Physics, Chinese Academy of Sciences developed some technics such as real-time PCR, long-PCR for accurate quantification of radiation induced damage and mutations, and in-depth investigation about the functional changes of mitochondria based on mtDNA damage and mutations were also carried out. In conclusion, the important role of mitochondrial study in radiation biology is underlined, and further study on mitochondrial study associated with late effect and metabolism changes in radiation biology is pointed out. (authors)

  10. Mutation frequencies in male mice and the estimation of genetic hazards of radiation in men: (specific-locus mutations/dose-rate effect/doubling dose/risk estimation)

    International Nuclear Information System (INIS)

    Russell, W.L.; Kelly, E.M.

    1982-01-01

    Estimation of the genetic hazards of ionizing radiation in men is based largely on the frequency of transmitted specific-locus mutations induced in mouse spermatogonial stem cells at low radiation dose rates. The publication of new data on this subject has permitted a fresh review of all the information available. The data continue to show no discrepancy from the interpretation that, although mutation frequency decreases markedly as dose rate is decreased from 90 to 0.8 R/min (1 R = 2.6 X 10 -4 coulombs/kg) there seems to be no further change below 0.8 R/min over the range from that dose rate to 0.0007 R/min. Simple mathematical models are used to compute: (a) a maximum likelihood estimate of the induced mutation frequency at the low dose rates, and (b) a maximum likelihood estimate of the ratio of this to the mutation frequency at high dose rates in the range of 72 to 90 R/min. In the application of these results to the estimation of genetic hazards of radiation in man, the former value can be used to calculate a doubling dose - i.e., the dose of radiation that induces a mutation frequency equal to the spontaneous frequency. The doubling dose based on the low-dose-rate data compiled here is 110 R. The ratio of the mutation frequency at low dose rate to that at high dose rate is useful when it becomes necessary to extrapolate from experimental determinations, or from human data, at high dose rates to the expected risk at low dose rates. The ratio derived from the present analysis is 0.33

  11. Induction of somatic mutations by low-dose X-rays: the challenge in recognizing radiation-induced events.

    Science.gov (United States)

    Nagashima, Haruki; Shiraishi, Kumiko; Ohkawa, Saori; Sakamoto, Yuki; Komatsu, Kenshi; Matsuura, Shinya; Tachibana, Akira; Tauchi, Hiroshi

    2017-10-19

    It is difficult to distinguish radiation-induced events from spontaneous events during induction of stochastic effects, especially in the case of low-dose or low-dose-rate exposures. By using a hypersensitive system for detecting somatic mutations at the HPRT1 locus, we investigated the frequency and spectrum of mutations induced by low-dose X-rays. The mutant frequencies induced by doses of >0.15 Gy were statistically significant when compared with the spontaneous frequency, and a clear dose dependency was also observed for mutant frequencies at doses of >0.15 Gy. In contrast, mutant frequencies at doses of 0.2 Gy. Our observations suggest that there could be a critical dose for mutation induction at between 0.1 Gy and 0.2 Gy, where mutagenic events are induced by multiple DNA double-strand breaks (DSBs). These observations also suggest that low-dose radiation delivered at doses of <0.1 Gy may not result in DSB-induced mutations but may enhance spontaneous mutagenesis events. © The Author 2017. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

  12. Age-related increase in the rate of spontaneou and γ-ray-induced hprt mutations in mouse spleen lymphocytes

    International Nuclear Information System (INIS)

    Gazlev, A.I.; Podlutskii, A.Ya.; Bradbury, R.

    1994-01-01

    Endogenous and exogenous factors continually afflict DNA of cells of organisms. A certain amount of the damage is accumulated causing mutations, increasing the risk of malignacies, impairing cell functions, and upsetting the body's homeostasis. The research reported here studies the rates of spontaneous hprt nmutationsand those induced you ggammairradiation in the splenocytes of mice at various ages. The rate of spontaneous and induced hprt gene mutations increases with aging. In gamma irradiated mice the rate of radiation-induced mutations depended on the absorbed dose and age, with the rate 2.3-3.0 fold higher in 104-110 week old mice than in younger pups. 15 refs., 1 tab

  13. Mutations induced by X-radiation in the yeast Schizosaccharomyces pombe

    International Nuclear Information System (INIS)

    Loprieno, N.; Barale, R.; Baroncelli, S.; Cammellini, A.; Melani, M.; Nieri, R.; Nozzolini, M.; Rossi, A.M.; Pisa Univ.

    1975-01-01

    Experiments on strains of yeast with different genetic backgrounds were done to evaluate the kinetics of inactivation and mutation induction by X-radiation. A system of forward mutation induction in five loci was used and a specific mutation rate was evaluated for the wild type. From a comparison of observations with wild type and radiation-sensitive strains, it may be assumed that in this yeast, mutations are mainly the result of a repair-active process. The range of genotypic and phenotypic influence upon the specific locus mutation rate was evaluated with appropriate biological material and experiments

  14. Specific-locus mutation frequencies in mouse stem-cell spermatogonia at very low radiation dose rates, and their use in the estimation of genetic hazards of radiation in man

    International Nuclear Information System (INIS)

    Russell, W.L.; Kelly, E.M.

    1982-01-01

    Experiments were undertaken to augment the information on the lowest radiation dose rates feasible for scoring transmitted induced mutations detected by the specific-locus method in the mouse. This is the type of information most suitable for estimating genetic hazards of radiation in man. The results also aid in resolving conflicting possibilities about the relationship between mutation frequency and radiation dose at low dose rates

  15. Strong effects of ionizing radiation from Chernobyl on mutation rates

    OpenAIRE

    M?ller, Anders Pape; Mousseau, Timothy A.

    2015-01-01

    In this paper we use a meta-analysis to examine the relationship between radiation and mutation rates in Chernobyl across 45 published studies, covering 30 species. Overall effect size of radiation on mutation rates estimated as Pearson's product-moment correlation coefficient was very large (E = 0.67; 95% confidence intervals (CI) 0.59 to 0.73), accounting for 44.3% of the total variance in an unstructured random-effects model. Fail-safe calculations reflecting the number of unpublished null...

  16. Radiation in relation to mutation rate, mutational damage and human ill-health

    International Nuclear Information System (INIS)

    Roberts, P.B.

    1976-09-01

    The effect of radiation in increasing the frequency of gene mutations is now reasonably understood. We discuss first how an increase in the mutation rate is reflected in the mutational damage expressed in populations. It is shown that the mutational damage, assessed by the loss of fitness in a population or the number of eventual gene extinctions, is equal to the number of new mutations arising per generation or the mutation rate. In a population of stable size, a dose of 1 rem given to 10 6 people leads to roughly 600 gene extinctions when summed over all ensuing generations if the dose is applied to only one generation; this number of extinctions will occur in each succeeding generation if the dose is given to every generation. However, the concept of genetic extinction, although quantifiable, is of limited value in assessing radiation risks since its impact on human ill-health is very speculative. In particular, no estimate can be made of the total cost of effects which are minor in each individual in which they arise, but which, because they are so minor, persist in the population for many generations. The best current estimate is for 14-140 obvious defects in the first few generations following exposure of 10 6 people to a dose of 1 rem. (auth.)

  17. Germline mutation rates in families residing in high level natural radiation areas of Kerala coast in southwest India

    International Nuclear Information System (INIS)

    Das, Birajalaxmi; Ghosh, Anu; Ahmad, Shazia; Saini, DivyaIakshmi; Chauhan, P.S.; Seshadri, M.

    2010-01-01

    For this study, 200 nuclear families have been analyzed using over 40 mini- and microsatellite markers. Cord blood samples for the child and peripheral blood samples for the parent(s) were collected in EDTA vacuutainers from the hospital units located in High Level Natural Radiation Areas (HLNRA) and Normal Level Natural Radiation Areas (NLNRA). Both the parents of the newborn were exposed to the background dose. The families were grouped into four distinct dose groups - NLNRA group 5.00 mGy/year. An overall mutation rate of 2.08 X 10 -3 per cell per generation was observed for NLNRA and 2.12 X 10 -3 per cell per generation for HLNRA families. No radiation induced dose response was observed for the stratified groups. Thus, this study shows that mutation rates at mini- and microsatellites in the off springs of the parents living in the high background radiation areas of Kerala does not vary with radiation exposure. This is the first report to understand germline mutation rates at hypervariable loci in families residing in high level natural radiation areas of the world

  18. Strong effects of ionizing radiation from Chernobyl on mutation rates.

    Science.gov (United States)

    Møller, Anders Pape; Mousseau, Timothy A

    2015-02-10

    In this paper we use a meta-analysis to examine the relationship between radiation and mutation rates in Chernobyl across 45 published studies, covering 30 species. Overall effect size of radiation on mutation rates estimated as Pearson's product-moment correlation coefficient was very large (E = 0.67; 95% confidence intervals (CI) 0.59 to 0.73), accounting for 44.3% of the total variance in an unstructured random-effects model. Fail-safe calculations reflecting the number of unpublished null results needed to eliminate this average effect size showed the extreme robustness of this finding (Rosenberg's method: 4135 at p = 0.05). Indirect tests did not provide any evidence of publication bias. The effect of radiation on mutations varied among taxa, with plants showing a larger effect than animals. Humans were shown to have intermediate sensitivity of mutations to radiation compared to other species. Effect size did not decrease over time, providing no evidence for an improvement in environmental conditions. The surprisingly high mean effect size suggests a strong impact of radioactive contamination on individual fitness in current and future generations, with potentially significant population-level consequences, even beyond the area contaminated with radioactive material.

  19. Molecular analysis of radiation-induced mutations in vitro

    International Nuclear Information System (INIS)

    Kronenberg, A.

    1996-01-01

    This review will focus on the nature of specific locus mutations detected in mammalian cells exposed in vitro to different types of ionizing radiations. Ionizing radiation has been shown to produce a wide variety of heritable alterations in DNA. These range from single base pair substitutions to stable loss or translocation of large portions of whole chromosomes. Data will be reviewed for certain test systems that reveal different mutation spectra. Techniques for the analysis of molecular alterations include applications of the polymerase chain reaction, some of which may be coupled with DNA sequence analysis, and a variety of hybridization-based techniques. The complexity of large scale rearrangements is approached with cytogenetic techniques including high resolution banding and various applications of the fluorescence in situ hybridization (FISH) technique. Radiation-induced mutant frequencies and mutation spectra are a function of the linkage constraints on the recovery of viable mutants for a given locus and test system. 44 refs

  20. Development of radiation-induced mutation techniques and functional genomics studies

    International Nuclear Information System (INIS)

    Kim, Dong Sub; Kang, Si Yong; Kim, Jin Baek

    2012-01-01

    This project has been performed to develop plant genetic resources using radiation (gamma-rays, ion-beam, space environments), to conduct functional genomics studies with mutant resources, and to develop new radiation plant breeding techniques using various radiation sources during 3 years. In the first section, we developed flower genetic resources, functional crop resources, and bio-industrial plant resources. In the second section, we cloned several mutated genes and studied mechanisms of gene expression and genetic diversity of mutations induced by gamma-rays. In the third section, we developed new plant breeding techniques using gamma-phytotron, heavy ion-beam, and space environments. Based on these results, a total of 8 cultivars containing Chrysanthemum, Hibiscus, kenaf, rice, and soybean were applied for plant variety protection (PVP) and a total of 4 cultivars were registered for PVP. Also, license agreement for the dwarf type Hibiscus mutant 'Ggoma' was conducted with Supro co. and the manufacturing technology for natural antioxidant pear-grape vinegar was transferred into Enzenic co. Also, 8 gene sequences, such as F3'H and LDOX genes associated with flower color in Chrysanthemum and EPSPS gene from Korean lawn grass, were registered in the database of National Center for Biotechnology Information (NCBI). In the future study, we will develop new radiation mutation breeding techniques through the mutation spectrum induced by various radiation sources, the studies for mechanism of the cellular response to radiation, and the comparative·structural·functional genomics studies for useful traits

  1. Genomic mutation study for long-term cells induced by carbon ions

    International Nuclear Information System (INIS)

    Wang, X.; Furusawa, Y.; Suzuki, M.; Hirayama, R.; Matsumoto, Y.; Qin, Y.

    2007-01-01

    Complete text of publication follows. Objective: Densely ionizing (high LET) radiation can increase the relative biological effectiveness of cell and tissue. Astronauts in the space exploration have the potential exposure of chronic low-dose radiations in the field of low-flux galactic cosmic rays (GCR) and the subsequent biological effects have become one of the major concerns of space science. Furthermore, Heavy ions also are used new radiation therapy owing increased lethal effectiveness of high LET radiation. During radiation therapy, normal tissues also are exposed to ionizing radiation. Radiation can induce genomic mutation and instability in descendants of irradiated cells. Induction of genomic instability can represent one of the initiating steps leading to malignant transformation. Higher frequencies of mutation can be expected to provide higher rates of carcinogenicity with human exposure. Therefore, the study of radiation induced genomic mutation and instability is relevant to the estimates of the risk of secondary malignancies associated with radiation therapy and the carcinogenic effects of space environmental radiation. The hypoxanthine-guanine phosphoribosyltransferase (hprt) locus has been the most commonly used as a target gene for mutation detection studies. In this study, we investigated the generation expression dependence of mutation induction on HPRT locus in CHO cells irradiated with carbon ions. Methods: Chinese hamster ovary (CHO) cells were irradiated with graded doses of carbon ions (290MeV/u, LET:13kev/um) accelerated with Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radiological Sciences(NIRS). The survival effect of cells plated immediately after irradiation was measured with cell colony formation assay. After irradiation, cells were continues reseeding and cultures for lone-term proliferation. Cell samples were collected at 6, 12, 18, 24, 30, 37 and 44 days post irradiation. Mutation induction of cell

  2. Radiation induced mutations in Phaseolus vulgaris L

    International Nuclear Information System (INIS)

    Al-Rubeai, M.A.F.

    1982-01-01

    A selection of various macro- and micro-mutations was undertaken in the M2 generation of Phaseolus vulgaris cultivars after seed exposure to acute gamma radiation doses of 2.5, 5, 7, 10 and 15 Kr. The chlorophyll mutation was positively correlated with dose. Nevertheless, the highest frequency was at 7 Kr. Several interesting morphological mutants were observed. There were dwarf, stiff stem, shiny small leaf, narrow leaf and green giant mutants. Two selected micromutants were superior in seed yield capacity to their parents. The high yields were related to the high number of pods per plant. In 'The Prince' (seed color: red with beige marbling) several mutants with seeds of black color marbled with beige were selected. These seeds gave M3 segregants exhibiting a range of seed colors including white. Many of these M3 plants were short, early flowering and highly sterile. The work demonstrated that the pigmentation character can readily be changed, and confirmed that the variability induced by radiation can be exploited to obtain desirable mutations. (Author) [pt

  3. Development of radiation-induced mutation techniques and functional genomics studies

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Sub; Kang, Si Yong; Kim, Jin Baek [KAERI, Daejeon (Korea, Republic of); and others

    2012-01-15

    This project has been performed to develop plant genetic resources using radiation (gamma-rays, ion-beam, space environments), to conduct functional genomics studies with mutant resources, and to develop new radiation plant breeding techniques using various radiation sources during 3 years. In the first section, we developed flower genetic resources, functional crop resources, and bio-industrial plant resources. In the second section, we cloned several mutated genes and studied mechanisms of gene expression and genetic diversity of mutations induced by gamma-rays. In the third section, we developed new plant breeding techniques using gamma-phytotron, heavy ion-beam, and space environments. Based on these results, a total of 8 cultivars containing Chrysanthemum, Hibiscus, kenaf, rice, and soybean were applied for plant variety protection (PVP) and a total of 4 cultivars were registered for PVP. Also, license agreement for the dwarf type Hibiscus mutant 'Ggoma' was conducted with Supro co. and the manufacturing technology for natural antioxidant pear-grape vinegar was transferred into Enzenic co. Also, 8 gene sequences, such as F3'H and LDOX genes associated with flower color in Chrysanthemum and EPSPS gene from Korean lawn grass, were registered in the database of National Center for Biotechnology Information (NCBI). In the future study, we will develop new radiation mutation breeding techniques through the mutation spectrum induced by various radiation sources, the studies for mechanism of the cellular response to radiation, and the comparative{center_dot}structural{center_dot}functional genomics studies for useful traits.

  4. R and D activities on radiation induced mutation breeding

    International Nuclear Information System (INIS)

    Lapade, A.G.; Asencion, A.B.; Santos, I.S.; Grafia, A.O.; Veluz, AM.S.; Barrida, A.C.; Marbella, L.J.

    1996-01-01

    This paper summarizes the accomplishments, prospects and future plans of mutation breeding for crop improvement at the Philippine Nuclear Research Institute (PNRI). Mutation induction has become a proven way creating variation within a crop variety and inducing desired attributes that cannot be found in nature or have been lost during evolution. Several improved varieties with desirable traits were successfully developed through induced mutation breeding at our research institute. In rice, mutation breeding has resulted in the development of new varieties: (1) PARC 2, (2) Milagrosa mutant, (3) Bengawan mutant and (4) Azmil mutant. Mutation breeding in leguminous crops has led to the induction of an improved L 114 soybean mutant that is shorter that the original variety but yield about 40% more. Several PAEC mungbean varieties characterized with long pods that are non-shattering were also induced. In asexually propagated crops, an increase in yield and chlorophyll mutants were obtained in sweet potatos. Likewise, chlorophyll mutant which look-like 'ornamental bromeliads' and a mutant with reduced spines have been developed in pineapple Queen variety. At present, we have started a new project in mutation breeding in ornamentals. Tissue culture is being utilized in our mutation breeding program. In the near future, radiation induced mutagenesis coupled with in vitro culture techniques on protoplast culture and somatic hybridization will be integrated into our mutation breeding program to facilitate the production of new crop varieties. (author)

  5. Spontaneous mutation rates and the rate-doubling dose

    International Nuclear Information System (INIS)

    Von Borstel, R.C.; Moustaccki, E.; Latarjet, R.

    1978-01-01

    The amount of radiation required to double the frequency of mutations or tumours over the rate of those that occur spontaneously is called the rate-doubling dose. An equivalent concept has been proposed for exposure to other environmental mutagens. The doubling dose concept is predicated on the assumption that all human populations have the same spontaneous mutation rate, and that this spontaneous mutation rate is known. It is now established for prokaryotes and lower eukaryotes that numerous genes control the spontaneous mutation rate, and it is likely that the same is true for human cells as well. Given that the accepted mode of evolution of human populatons is from small, isolated groups of individuals, it seems likely that each population would have a different spontaneous mutation rate. Given that a minimum of twenty genes control or affect the spontaneous mutation rate, and that each of these in turn is susceptible to spontaneously arising or environmentally induced mutations, it seems likely that every individual within a population (except for siblings from identical multiple births) will have a unique spontaneous mutation rate. If each individual in a population does have a different spontaneous mutation rate, the doubling dose concept, in rigorous terms, is fallacious. Therefore, as with other concepts of risk evaluation, the doubling dose concept is subject to criticism. Nevertheless, until we know individual spontaneous mutation rates with precision, and can evaluate risks based on this information, the doubling dose concept has a heuristic value and is needed for practical assessment of risks for defined populations. (author)

  6. A novel radiation-induced p53 mutation is not implicated in radiation resistance via a dominant-negative effect.

    Directory of Open Access Journals (Sweden)

    Yunguang Sun

    Full Text Available Understanding the mutations that confer radiation resistance is crucial to developing mechanisms to subvert this resistance. Here we describe the creation of a radiation resistant cell line and characterization of a novel p53 mutation. Treatment with 20 Gy radiation was used to induce mutations in the H460 lung cancer cell line; radiation resistance was confirmed by clonogenic assay. Limited sequencing was performed on the resistant cells created and compared to the parent cell line, leading to the identification of a novel mutation (del at the end of the DNA binding domain of p53. Levels of p53, phospho-p53, p21, total caspase 3 and cleaved caspase 3 in radiation resistant cells and the radiation susceptible (parent line were compared, all of which were found to be similar. These patterns held true after analysis of p53 overexpression in H460 cells; however, H1299 cells transfected with mutant p53 did not express p21, whereas those given WT p53 produced a significant amount, as expected. A luciferase assay demonstrated the inability of mutant p53 to bind its consensus elements. An MTS assay using H460 and H1299 cells transfected with WT or mutant p53 showed that the novel mutation did not improve cell survival. In summary, functional characterization of a radiation-induced p53 mutation in the H460 lung cancer cell line does not implicate it in the development of radiation resistance.

  7. Radiation-induced germ-line mutations detected by a direct comparison of parents and children DNA sequences containing SNPs

    International Nuclear Information System (INIS)

    Morimyo, M.; Hongo, E.; Higashi, T.; Wu, J.; Matsumoto, I.; Okamoto, M.; Kawano, A.; Tsuji, S.

    2003-01-01

    Full text: Germ-line mutation is detected in mice but not in humans. To estimate genetic risk of humans, a new approach to extrapolate from animal data to humans or to directly detect radiation-induced mutations in man is expected. We have developed a new method to detect germ-line mutations by directly comparing DNA sequences of parents and children. The nucleotide sequences among mouse strains are almost identical except SNP markers that are detected at 1/1000 frequency. When gamma-irradiated male mice are mated with female mice, heterogeneous nucleotide sequences induced in children DNA are a candidate of mutation, whose assignment can be done by SNP analysis. This system can easily detect all types of mutations such as transition, transversion, frameshift and deletion induced by radiation and can be applied to humans having genetically heterogeneous nucleotide sequences and many SNP markers. C3H male mice of 8 weeks of gestation were irradiated with gamma rays of 3 and 1 Gy and after 3 weeks, they were mated with the same aged C57BL female mice. After 3 weeks breeding, DNA was extracted from parents and children mice. The nucleotide sequences of 150 STS markers containing 300-900 bp and SNPs of parents and children DNA were determined by a direct sequencing; amplification of STS markers by Taq DNA polymerase, purification of PCR products, and DNA sequencing with a dye-terminator method. At each radiation dose, a total amount of 5 Mb DNA sequences were examined to detect radiation-induced mutations. We could find 6 deletions in 3 Gy irradiated mice but not in 1 Gy and control mice. The mutation frequency was about 4.0 x 10 -7 /bp/ Gy or 1.6 x 10 -4 /locus/Gy, and suggested the non-linear increase of mutation rate with dose

  8. Base substitutions, frameshifts, and small deletions constitute ionizing radiation-induced point mutations in mammalian cells

    International Nuclear Information System (INIS)

    Grosovsky, A.J.; de Boer, J.G.; de Jong, P.J.; Drobetsky, E.A.; Glickman, B.W.

    1988-01-01

    The relative role of point mutations and large genomic rearrangements in ionizing radiation-induced mutagenesis has been an issue of long-standing interest. Recent studies using Southern blotting analysis permit the partitioning of ionizing radiation-induced mutagenesis in mammalian cells into detectable deletions and major genomic rearrangements and into point mutations. The molecular nature of these point mutations has been left unresolved; they may include base substitutions as well as small deletions, insertions, and frame-shifts below the level of resolution of Southern blotting analysis. In this investigation, we have characterized a collection of ionizing radiation-induced point mutations at the endogenous adenine phosphoribosyltransferase (aprt) locus of Chinese hamster ovary cells at the DNA sequence level. Base substitutions represented approximately equal to 2/3 of the point mutations analyzed. Although the collection of mutants is relatively small, every possible type of base substitution event has been recovered. These mutations are well distributed throughout the coding sequence with only one multiple occurrence. Small deletions represented the remainder of characterized mutants; no insertions have been observed. Sequence-directed mechanisms mediated by direct repeats could account for some of the observed deletions, while others appear to be directly attributable to radiation-induced strand breakage

  9. Effects of smoke and tea on radiation-induced bone marrow cell mutation and marrow inhibition

    International Nuclear Information System (INIS)

    Gao Yong; Zhang Weiguang

    2004-01-01

    Objective: To provide scientific information for the prevention and treatment of the radiation damage by analyzing the effects of smoke and tea on radiation-induced bone marrow cell mutation and marrow inhibition. Methods: 7 group mice were exposed to smoke and/or tea and/or radiation respectively. There were also b blank control group and a cyclophosphamide positive control group. The frequencies of micronucleated polychromatic erythrocytes (MPCE), the ratio of polychromatic erythrocytes (PCE) to mature erythrocytes (RBC) in marrow, and the count of peripheral blood hemoleukocyte were observed. Results: The frequencies of MPCE in the groups irradiated with γ-rays were significantly higher than that in the blank control group (P<0.05 or 0.01). The smoke + radiation group's frequency was significantly higher than single radiation group (P<0.05). The ratios of PCE to RBC in the groups irradiated were significantly lower than that in the blank control group (P<0.01). The counts of peripheral blood hemoleukocyte in the groups irradiated were significantly lower than the blank control group (P<0.01). Conclusion: Radiation were able to cause marrow cell mutation and induce marrow inhibition. Smoke increases the effect of radiation-induced marrow cell mutation. Tea and smoke could not affect radiation-induced bone marrow inhibition

  10. Induction of different types of mutations in yeast Saccharomyces serevisiae by γ-radiation

    International Nuclear Information System (INIS)

    Lyubimova, K.A.; Shvaneva, N.V.; Koltovaya, N.A.

    2005-01-01

    Several tester systems were used to study a wide spectrum of genetic changes induced by γ-radiation in the yeast Saccharomyces cerevisiae. The tester systems allow one to identify a loss of chromosomes, recombination (crossing over) and point mutations (frame shifts and base-pair substitutions.) Large genome changes were induced by γ-rays more efficiently than the point mutations. The dose dependence of the point mutations frequency was linear. Spontaneous and induced mutation rates per base pair corresponded with the known literature data for the same tester systems. Our finding shows that the used tester systems are not specific. They are useful for further study of mutations induced by ionizing radiation with various physical characteristics

  11. A radiation-induced compact type Granny Smith apple mutation

    International Nuclear Information System (INIS)

    Hurter, N.; Van Tonder, M.J.

    1982-01-01

    More successful compact mutant clones of Granny Smith apple are being sought, for those that have so far arisen naturally have undesirable tree and fruit charateristics. For this purpose, gamma rays from a Cobalt-60 radiation unit were used to induce mutant types artificially. One compact mutation of Granny Smith was produced via re-irradiation

  12. Specific-locus experiments show that female mice exposed near the time of birth to low-LET ionizing radiation exhibit both a low mutational response and a dose-rate effect

    International Nuclear Information System (INIS)

    Selby, P.B.; Lee, S.S.; Kelly, E.M.; Bangham, J.W.; Raymer, G.D.; Hunsicker, P.R.

    1991-01-01

    Female mice were exposed to 300 R of 73-93 R/min X-radiation either as fetuses at 18.5d post conception (p.c.) or within 9h after birth. Combining the similar results from these 2 groups yielded a specific-locus mutation frequency of 9.4x10 -8 mutation/locus/R, which is statistically significantly higher than the historical-control mutation frequency, but much lower than the rate obtained by irradiating mature and maturing oocytes in adults. Other females, exposed at 18.5 days p.c. to 300 R of 0.79 R/min γ-radiation, yielded a mutation frequency that was statistically significantly lower than the frequency at high dose rates. The low-dose-rate group also had markedly higher fertility. It appears that the doe-rate effect for mutations induced near the time of birth may be more pronounced than that reported for mature and maturing oocytes of adults. A hypothesis sometimes advanced to explain low mutation frequencies recovered from cell populations that experience considerable radiation-induced cell killing is that there is selection against mutant cells. The reason for the relatively low mutational response following acute irradiation in the experiments is unknown; however, the finding of a dose-rate effect in these oocytes in the presence of only minor radiation-induced cell killing (as judged from fertility) makes it seem unlikely that selection was responsible for the low mutational response following acute exposure. Had selection been an important factor, the mutation frequency should have increased when oocyte killing was markedly reduced. (author). 32 refs.; 5 figs.; 5 tabs

  13. Use of ionizing radiation induced mutation in the genetic development of plants

    International Nuclear Information System (INIS)

    Barragan, Raul; Rubio, Santiago

    1993-01-01

    The objective of this article is to present a general focus on the use of induced mutations in the improvement of plants. This article describes some basic aspects that must be well known by the breeder that hopes to incorporate in his programm the technique of induced mutation by radiations. In this paper are included the results of two trials done by the researchers of the department of plant breeding so that it can be used as reference to determinate the importance of this technique

  14. Mutation frequencies in male mice and the estimation of genetic hazards of radiation in men

    International Nuclear Information System (INIS)

    Russell, W.L.; Kelly, E.M.

    1982-01-01

    Estimation of the genetic hazards of ionizing radiation in men is based largely on the frequency of transmitted specific-locus mutations induced in mouse spermatogonial stem cells at low radiation dose rates. The publication of new data on this subject has permitted a fresh review of all the information available. The data continue to show no discrepancy from the interpretation that, although mutation frequency decreases markedly as dose rate is decreased from 90 to 0.8 R/min (1 R = 2.6 x 10/sup -4/ coulombs/kg) there seems to be no further change below 0.8 R/min over the range from that dose rate to 0.0007 R/min. Simple mathematical models are used to compute: (a) a maximum likelihood estimate of the induced mutation frequency at the low dose rates, and (b) a maximum likelihood estimate of the ratio of this to the mutation frequency at high dose rates in the range of 72 to 90 R/min. In the application of these results to the estimation of genetic hazards of radiation in man, the former value can be used to calcualte a doubling dose - i.e., the dose of radiation that induces a mutation frequency equal to the spontaneous frequency. The doubling dose based on the low-dose-rate data compiled here is 110 R. The ratio of the mutation frequency at low dose rate to to that at high dose rate is useful when it becomes necessary to extrapolate from experimental determinations, or from human data, at high dose rates to the expected risk at low dose rates. The ratio derived from the present analysis is 0.33

  15. Mutations induced by ultraviolet radiation affecting virulence in Puccinia striiformis

    International Nuclear Information System (INIS)

    Shang Hongsheng; Jing Jinxue; Li Zhenqi

    1994-01-01

    Uredospores of parent culture, cy 29-1, were treated by ultraviolet radiation and mutations to virulent were tested on resistant wheat cultivars inoculated with treated spores. 7 mutant cultures virulent to the test cultivars were developed with estimated mutation rate 10~6~10~4. The virulence of mutant cultures was different from the all known races of stripe rust. Resistance segregation to mutant cultures was detected in two test cultivars. The results suggested that mutation was important mechanism of virulence variation operative in asexual population of rust fungi

  16. Bystander effects in UV-induced genomic instability: Antioxidants inhibit delayed mutagenesis induced by ultraviolet A and B radiation

    Directory of Open Access Journals (Sweden)

    Dahle Jostein

    2005-01-01

    Full Text Available Abstract Background Genomic instability is characteristic of many types of human cancer. Recently, we reported that ultraviolet radiation induced elevated mutation rates and chromosomal instability for many cell generations after ultraviolet irradiation. The increased mutation rates of unstable cells may allow them to accumulate aberrations that subsequently lead to cancer. Ultraviolet A radiation, which primarily acts by oxidative stress, and ultraviolet B radiation, which initially acts by absorption in DNA and direct damage to DNA, both produced genomically unstable cell clones. In this study, we have determined the effect of antioxidants on induction of delayed mutations by ultraviolet radiation. Delayed mutations are indicative of genomic instability. Methods Delayed mutations in the hypoxanthine phosphoribosyl transferase (hprt gene were detected by incubating the cells in medium selectively killing hprt mutants for 8 days after irradiation, followed by a 5 day period in normal medium before determining mutation frequencies. Results The UVB-induced delayed hprt mutations were strongly inhibited by the antioxidants catalase, reduced glutathione and superoxide dismutase, while only reduced glutathione had a significant effect on UVA-induced delayed mutations. Treatment with antioxidants had only minor effects on early mutation frequenies, except that reduced glutathione decreased the UVB-induced early mutation frequency by 24 %. Incubation with reduced glutathione was shown to significantly increase the intracellular amount of reduced glutathione. Conclusion The strong effects of these antioxidants indicate that genomic instability, which is induced by the fundamentally different ultraviolet A and ultraviolet B radiation, is mediated by reactive oxygen species, including hydrogen peroxide and downstream products. However, cells take up neither catalase nor SOD, while incubation with glutathione resulted in increased intracellular levels of

  17. P53 Gene Mutation as Biomarker of Radiation Induced Cell Injury and Genomic Instability

    International Nuclear Information System (INIS)

    Mukh-Syaifudin

    2006-01-01

    Gene expression profiling and its mutation has become one of the most widely used approaches to identify genes and their functions in the context of identify and categorize genes to be used as radiation effect markers including cell and tissue sensitivities. Ionizing radiation produces genetic damage and changes in gene expression that may lead to cancer due to specific protein that controlling cell proliferation altered the function, its expression or both. P53 protein encoded by p53 gene plays an important role in protecting cell by inducing growth arrest and or cell suicide (apoptosis) after deoxyribonucleic acid (DNA) damage induced by mutagen such as ionizing radiation. The mutant and thereby dysfunctional of this gene was found in more than 50% of various human cancers, but it is as yet unclear how p53 mutations lead to neoplastic development. Wild-type p53 has been postulated to play a role in DNA repair, suggesting that expression of mutant forms of p53 might alter cellular resistance to the DNA damage caused by radiation. Moreover, p53 is thought to function as a cell cycle checkpoint after irradiation, also suggesting that mutant p53 might change the cellular proliferative response to radiation. P53 mutations affect the cellular response to DNA damage, either by increasing DNA repair processes or, possibly, by increasing cellular tolerance to DNA damage. The association of p53 mutations with increased radioresistance suggests that alterations in the p53 gene might lead to oncogenic transformation. Current attractive model of carcinogenesis also showed that p53 gene is the major target of radiation. The majority of p53 mutations found so far is single base pair changes ( point mutations), which result in amino acid substitutions or truncated forms of the p53 protein, and are widely distributed throughout the evolutionary conserved regions of the gene. Examination of p53 mutations in human cancer also shows an association between particular carcinogens and

  18. Mutagenesis applied to improve fruit trees. Techniques, methods and evaluation of radiation-induced mutations

    International Nuclear Information System (INIS)

    Donini, B.

    1982-01-01

    Improvement of fruit tree cultivars is an urgent need for a modern and industrialized horticulture on which is based the economic importance of many countries. Both the cross breeding and the mutation breeding are regarded as the methods to be used for creating new varieties. Research carried out at the CNEN Agriculture Laboratory on mutagenesis to improve vegetatively propagated plants, under the FAO-IAEA Co-ordinated Research Programme, has dealt with methods of exposure, types of radiations, conditions during and after the irradiation, mechanisms of mutation induction, methodology of isolation of somatic mutations and evaluation of radiation-induced mutations in fruit trees. Problems associated with these aspects have been evaluated, which is very important for the more efficient use of radiation in the mutation breeding. Mutants of agronomical importance (plant size reduction, early ripening, fruit colour change, nectarine fruit, self-thinning fruit) have been isolated in cherry, grape, apple, olive and peach and they are ready to be released. (author)

  19. Somatic mutations in leafs of tobacco seedlings induced by ionizing radiation and pesticide

    International Nuclear Information System (INIS)

    Shin, H. S.; Kim, J. K.; Song, H. S.; Lee, Y. I.

    2001-01-01

    Somatic mutations induced by the combined treatment of pesticide and ionizing radiation were analyzed in the leaves of tobacco seedlings. The pesticide (1,5 and 10 ppm of parathion) was sprayed directly onto the seedlings. The seedlings, with or without pretreatment of pesticide, were irradiated with 0.1 ∼10 Gy of gamma ray. The difference in the somatic mutation frequencies were not significant among groups treated with different concentration of pesticide. The somatic mutations in tobacco seedlings irradiated with gamma-ray showed a clear dose-response relationship in a range of 0.1 to 10 Gy. However, the combined treatment of pesticide and radiation did not cause any synergistic enhancement in the mutation frequencies. The highest efficiency in the induction of somatic mutations could be obtained by irradiating the seedlings with 5 Gy, 12 hours after 1 ppm of pesticide treatment, or 24 hours after 5 ppm of pesticide treatment

  20. Radiation induced chlorophyll mutations in rice

    International Nuclear Information System (INIS)

    Bari, G.; Mustafa, G.; Soomro, A.M.; Baloch, A.W.

    1985-01-01

    Air dried grains of four local varieties of rice were treated with gamma-rays and fast neutrons for determining their mutagenic effectiveness through the occurence of chlorophyll mutations. Fast neutrons were more effective in inducing chlorophyll mutations and the rice variety Basmati 370 produced maximum number of mutations followed by varieties Sonahri Sugdasi, Jajai 77 and Sada Gulab. The highest frequency of chlorophyll mutations was that of albina types followed by striata types. The xantha, viridis and tigrina types of mutations were less frequent. (authors)

  1. Predicting radiation effects on the development of leukemic stem cells based on studies of leukemias induced by high- and low-dose-rate radiation

    International Nuclear Information System (INIS)

    Hirouchi, Tokuhisa

    2012-01-01

    One of the most important causes of radiation-induced cancers, particularly leukemia, is gene mutations resulting from single and double strand breaks in the DNA. Tanaka et al. (2003) reported life shortening in specific pathogen free male and female B6C3F1 mice continuously exposed to γ rays at a low dose rate of 20 mGy/22 h/d for 400 days from 8 weeks of age. Early death due to cancer, mostly malignant lymphomas, was observed in both sexes. A significant increase in the incidence of myeloid leukemia, resulting in early death, was also reported in males. It is expected however, that at 20 mGy/22 h/d, which is equivalent to a dose of 15 μGy/min, DNA strand breaks induced in these cells are repaired soon after they occur. Murine leukemias induced by high-dose-rate radiation were also found in males, and 80% of the mice with leukemia had hemizygous deletions in chromosome 2 around the PU.1 gene and they appeared to be derived from DNA strand breaks. Majority of these leukemia showing hemizygous deletions in chromosome 2 revealed point mutations in the remaining alleles resulting in PU.1 inactivation, which was reported to be related to leukemogenesis. These point mutations are assumed to be independent of DNA strand breaks that occur immediately after irradiation, as they appear at later time after irradiation. This review discusses the effect of radiation-induced DNA strand breaks and also mutagenesis induced independently of DNA strand breaks in hematopoietic cells contributing to the development of the first leukemic stem cell. (author)

  2. Re-analysis of radiation-induced specific locus mutations in the mouse

    International Nuclear Information System (INIS)

    Abrahamson, S.; Wolff, S.

    1976-01-01

    It is stated that a re-analysis of published data on mouse mutation rates induced by x-and gamma rays suggests that the kinetics of induction can be analysed by fitting that data to a parabolic curve. This is interpreted to mean that a substantial proportion of the induced mutations results from gross chromosomal changes such as deletions, some of which are one-track and some of which are two-track. This analysis is based on the assumption that the shape of the dose curve, which in the female is concave upward, reflects the manner in which the mutations are induced rather than representing a one-track (linear) curve whose shape has been modified by differential repair. (author)

  3. Molecular cytogenetics of radiation-induced gene mutations in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Aleksandrov, I.D.; Aleksandrova, M.V.; Lapidus, I.L.; Karpovskij, A.L.

    1996-01-01

    The classical paradigm of spatially unrelated lesions for gene mutations and chromosomal exchange breakpoints induced by ionizing radiations in eukaryotic cells was re-examined in the experiments on the mapping of gamma-ray- or neutron-induced breakpoints in and outside of white (w) and vestigial (vg) genes of Drosophila melanogaster using the in situ hybridization of the large fragments of the genes under study with the polythene chromosomes of the relevant mutants. The results for the random sample of 60 inversion and translocation breakpoints analysed to date have shown that (i) 50% of them are mapped as the hot spots within big introns of both the genes, and (ii) 21 of 60 breaks (35%) are located outside of genes. It is important to note that 26% (16/60) of the breakpoints analysed are flanked by the deletions, the sizes of which vary from the quarter to a whole of the gene. It was found that the deletions flank both the inversion and translocation breakpoints and arise more often after action of neutrons than photons. An unexpectedly high frequency of the multiple-damaged w and vg mutants that have the gene/point mutation and additional, but separate, chromosome exchange (the so-called double- or triple-site mutants) has shown that the genetic danger of ionizing radiation is higher than usually accepted on the base of single gene/point mutation assessments. 11 refs., 3 figs

  4. Multi-mutational model for cancer based on age-time patterns of radiation effects: 2. Biological aspects

    Energy Technology Data Exchange (ETDEWEB)

    Mendelsohn, M.L.; Pierce, P.A.

    1997-09-04

    Biological properties of relevance when modeling cancers induced in the atom bomb survivors include the wide distribution of the induced cancers across all organs, their biological indistinguishability from background cancers, their rates being proportional to background cancer rates, their rates steadily increasing over at least 50 years as the survivors age, and their radiation dose response being linear. We have successfully described this array of properties with a modified Armitage-Doll model using 5 to 6 somatic mutations, no intermediate growth, and the dose-related replacement of any one of these time-driven mutations by a radiation-induced mutation. Such a model is contrasted to prevailing models that use fewer mutations combined with intervening growth. While the rationale and effectiveness of our model is compelling for carcinogenesis in the atom bomb survivors, the lack of a promotional component may limit the generality of the model for other types of human carcinogenesis.

  5. Radiation-Induced Mutation and Crop Improvement

    International Nuclear Information System (INIS)

    Lee, Y. I.; Song, H. S.; Kim, J. S.; Shin, I. C.; Lee, S. J.

    1987-01-01

    Radiation induced mutations have not only been used directly as a cultivar in crop plants, but also indirectly as a genetic resource that is essential to conventional plant breeding. M 1 plant survivals of three rice cultivars treated with gamma rays of 200-350 Gy varied from 30-40%. The survival of the Sawing variety was less sensitive to radiation, but its fertility was more sensitive in comparison with Seomjin and Sponging. Various dwarf or semi-dwarf mutants and early=matured mutants have been selected in the M 2 and M 3 generations of the three rice cultivars irradiated with gamma rays. Other desirable mutants also have been selected, such as high-yielding, high-tailoring and disease-resistant. The genetic nature of most of the selected short calm and earliness mutants was fixed in M 2 or M 3 generations. Dwarfism of IEAR 308 and Monogynol 10 were found to have a single recessive gene. However, the dwarf of IEAR 308 has a recessive deficit phenomenon. The highest genetic heritability of plant height was observed in the cross combination of Monogynol 10 Χ Pawling

  6. Mutations induced in plant breeding

    International Nuclear Information System (INIS)

    Barriga B, P.

    1984-01-01

    The most significant aspects of the use of ionizing radiations in plant breeding are reviewed. Aspects such as basic principles of mutation, expression and selection in obtention of mutants, methods for using induced mutations and sucess achieved with this methodology in plant breeding are reviewed. Results obtained in a program of induced mutation on wheat for high content of protein and lysine at the Universidad Austral de Chile are presented. (Author)

  7. Mutations induced in plant breeding

    Energy Technology Data Exchange (ETDEWEB)

    Barriga B, P. (Universidad Austral de Chile, Valdivia. Inst. de Produccion y Sanidad Vegetal)

    1984-10-01

    The most significant aspects of the use of ionizing radiations in plant breeding are reviewed. Aspects such as basic principles of mutation, expression and selection in obtention of mutants, methods for using induced mutations and sucess achieved with this methodology in plant breeding are reviewed. Results obtained in a program of induced mutation on wheat for high content of protein and lysine at the Universidad Austral de Chile are presented.

  8. Genetic and molecular analyses of UV radiation-induced mutations in the fem-3 gene of Caenorhabditis elegans

    Energy Technology Data Exchange (ETDEWEB)

    Hartman, P S; De Wilde, D; Dwarakanath, V N [Texas Christian Univ., Fort Worth, TX (United States). Dept. of Biology

    1995-06-01

    The utility of a new target gene (fem-3) is described for investigating the molecular nature of mutagenesis in the nematode Caenorhabditis elegans. As a principal attribute, this system allows for the selection, maintenance and molecular analysis of any type of mutation that disrupts the gene, including deletions. In this study, 86 mutant strains were isolated, of which 79 proved to have mutations in fem-3. Twenty of these originally tested as homozygous inviable. Homozygous inviability was expected, as Stewart and coworkers had previously observed that, unlike in other organisms, most UV radiation-induced mutations in C. elegans are chromosomal rearrangements of deficiencies (Mutat. Res 249, 37-54, 1991). However, additional data, including Southern blot analyses on 49 of the strains, indicated that most of the UV radiation-induced fem-3 mutations were not deficiencies, as originally inferred from their homozygous inviability. Instead, the lethals were most likely ``coincident mutations`` in linked, essential genes that were concomitantly induced. As such, they were lost owing to genetic recombination during stock maintenance. As in mammalian cells, yeast and bacteria, the frequency of coincident mutations was much higher than would be predicted by chance. (Author).

  9. A challenge to mutation theory of radiation carcinogenesis

    International Nuclear Information System (INIS)

    Watanabe, Masami

    2006-01-01

    This paper presents an objection against the commonly accepted mutation theory in radiation carcinogenesis. First, author's studies of X-ray irradiated syrian hamster embryo (SHE) cells on malignant morphological changes and mutational change of HGPRT gene showed that the changing patterns were quite different, and as well, other studies in mice gave the essentially similar results. Thus radiation-induced carcinogenesis in cells does not simply occur by an accumulation of radiation-induced mutation. Second, as cultured cells usually used for oncogenesis studies already have the infinitively proliferative ability, the author used the primary cell culture obtained from the rodent embryo. Even those cells became immortal to be cancerous after repeated culture passage with the higher frequency of 10 3 -10 4 relative to somatic cell mutation. Cells thus seem to be easily changeable to cancerous ones. Bystander effect can cause transformation in non-irradiated cells and genetic instability by radiation can form the potentially unstable chromatin region, which induces telomere instability. The author has found that, while short-lived radicals yielded by X-ray irradiation attack DNA to induce cell death and chromosome aberration, long-lived radicals in biomolecules do not, but can cause mutation and carcinogenesis, which are reduced by vitamine C supplementation. The author concludes that the primary target in the radiation carcinogenesis in cells and even in the whole individuals is conceivably protein and not DNA. (T.I.)

  10. Retrospective genetic study of germinative mutations in Str loci of individuals potentially exposed to ionizing radiation

    International Nuclear Information System (INIS)

    Costa, Emilia Oliveira Alves

    2010-01-01

    The Brazilian radiological accident that occurred in 1987, in Goiania, it was a terrible radiation episode. As a consequence, hundreds of people were contaminated due to the Cesium-137 radiation. Recently, many studies had shown that genome instabilities, such as, mutations, chromosomal aberrations, micronuclei formation and micro satellite instability and a delay on cellular death are usually reported on mammal cells exposed to ionizing radiation, being considered as a manly risk to humans. Mutations can be spontaneous, and the occurrence is dependent on the organism, or, induced, being associated to mutagenic exposition. Ionizing radiations are an example of physical and mutagenic agents that could harm the cell repair and could cause the development of many types of cancer. The evaluation of the biological effects of the ionizing radiation, in somatic and germ line cells, with a consequent determination of the radio-induced mutations, it is extremely important to estimate the genetic risks, manly in population exposed to radiation. The analyses of repetitive DNA sequences have been demonstrated that such sequences are prone to high rates of spontaneous mutations. The minisatellites and microsatellites have been used to demonstrate the induction of germ line mutation rates on mouse, humans, among others organisms. The aim of the present study was to analyze the frequency of microsatellite alterations to determine the mutation rates occurred in germ cells of the parents exposed to the ionizing radiation of the Cesium-137. The studied group was constitute of 10 families of individuals accidentally exposed to Cesium-137 and by the control group constituted by 645 healthy individuals who carried out paternity tests on 2009. We found only one mutation of paternal origin in the D8S1179 locus on the exposed group, being the mutation rate of 0.002. In the control group, we found 01 mutation on D16S539 loei and on D3S1358; 02 mutations on Penta E loeus; 04 mutations on D

  11. The influence of large deletions on the mutation frequency induced by tritiated water and X-radiation in male Drosophila melanogaster post-meiotic germ cells

    International Nuclear Information System (INIS)

    Fossett, N.G.; Byrne, B.J.; Kelley, S.J.; Tucker, A.B.; Arbour-Reily, P.; Lee, W.R.

    1994-01-01

    Tritium beta radiation ( 3 H β-radiation) in the form of tritiated water was used to induce mutations at the alcohol dehydrogenase (Adh) locus in male Drosophila melanogaster post-meiotic germ cells. All 23 Adh null mutations were large deletions (>20 kb), determined by genetic complementation and Southern blot analyses. 27 Adh null mutations have been induced by 100-kVp X-rays and have been genetically and molecularly characterized. In contrast to 3 H β-radiation, 100-kVp X-rays induced a bimodal distribution of Adh null mutations, intragenic mutations, ≤250 bp, and large deletions, >100 kb. A statistically significant difference was observed between the frequency of large deletions (23/23 or 1.0) induced by 3 H β-radiation and the frequency of large deletions (19/27 or 0.7) induced by 100-kVp X-rays. However, a statistical difference was not observed between the size distribution of the large deletions induced by 3 H β-radiation and X-rays. The relative deletion frequency (RDF) induced by 3 H β-radiation and 100-kVp X-rays was (1.0/0.7=1.4). The relative biological effectiveness (RBE) of these two radiation sources was 1.4, determined from the ratio of the regression coefficients of the respective 3 H β-radiation and X-ray sex-linked recessive lethal (SLRL) dose-response data. The large difference in size between the two classes of X-ray-induced Adh null mutations and the increase in mutation frequency and deletion frequency for 3 H β-radiation with respect to X-rays may indicate that the relative deletion frequency (RDF) is the molecular biological basis for the increase in the RBE for radiation sources with a mean LET value ≤10 keV/μm

  12. Different effects of dose rate on radiation-induced mutation frequency in various germ-cell stages of the mouse, and their implications for the analysis of tumorigenesis

    International Nuclear Information System (INIS)

    Russell, W.L.

    1979-01-01

    The following factors affecting mutation induction by radiation in mice are discussed: dose rate, cell stage, and sex. It is suggested that for cancers of presumed mutational origin, the risk from chronic radiation exposure may be only one-third the risk from acute exposure. This is based only on responses of spermatogonia; other cell types behave quite differently. Specific and general applications are discussed

  13. Characterization of carbon ion-induced mutations in Arabidopsis thaliana

    International Nuclear Information System (INIS)

    Shikazono, N.; Suzuki, C.; Kitamura, S.; Watanabe, H.; Tano, S.; Tanaka, A.

    2003-01-01

    Full text: Irradiation of Arabidopsis thaliana by carbon ions was carried out to investigate the mutational effect of ion particles in higher plants. The averaged mutation rate of carbon ions was 2.0 X 10 -6 / Gy, which was 18-fold higher than that of electrons. PCR analysis of the carbon ion-induced mutants showed that, out of 28 mutant alleles, 14 had point-like mutations within the gene, while 14 contained large structural alterations. In the case of 12 electron-induced mutants, 9 had point-like mutations within the gene, while 3 contained large structural alterations. These results suggest that carbon ions are more likely to induce large structural alterations compared with electrons. Further sequence analysis revealed that most of the point-like mutations induced by carbon ions were short deletions. In the case of rearrangements, DNA strand breaks were found to be rejoined using, if present, short homologous sequences for both types of radiation. After carbon ion-irradiation, small deletions were frequently observed around the breakpoints, whereas duplications of terminal sequence were found after electron-irradiation. These results suggest that non-homologous end joining (NHEJ) pathway operates after plant cells are exposed to both ion particles and electrons but that different mode of rejoining deals with the broken ends produced by each radiation. From the present results, it seems reasonable to assume that carbon ions could predominantly induce null mutations in Arabidopsis. The fact that the molecular nature of carbon ion-induced mutation was different from that of electrons and that the molecular mechanisms of cells to induce mutations appeared to be also different implicates that ion particle is not only valuable as a new mutagen but also useful as a new tool to study repair mechanisms of certain types of DNA damage

  14. Radiation-induced mutations in sweet cherry (Prunus avium L.)

    Energy Technology Data Exchange (ETDEWEB)

    Saamin, S [Cocoa and Coconut Research Division, Malaysian Agricultural Research and Development Institute (Malaysia); Thompson, M M [Department of Horticulture, Oregon State University, Corvallis, OR (United States)

    1989-01-01

    Full text: Dormant scions of 'Bing' were exposed to 1-2.5 kR gamma radiation. The main buds were excised and the scions grafted to allow the growth of accessory buds into primary shoots. The frequency and types of mutations were described in a population of 3307 M{sub 1}V{sub 2} shoot. The overall mutation frequency was 2.7% incl. 0.15% growth-reduced mutants. The experiment was repeated using 3kR and 4kR fractionated doses in water. Differences in mutation frequency at 3kR and 4kR were not significant. Of 2765 surviving M{sub 1}V{sub 2} shoots derived from irradiation of accessory buds of both standard and V{sub 1} shoots, the overall mutation frequency was 3.3% incl. 1.7% partial leaf mutants, 1.0% leaf mutants, and 0.54% growth-reduced mutants. For maximum mutation rate with adequate survival we suggest acute irradiation of accessory buds in air at dosages approximating LD50. Mutant sectors in M{sub 1}V{sub 1} shoots derived from accessory buds are larger than those from main buds, as revealed by the higher number of mutant repeats. (author)

  15. Studies of adaptive response and mutation induction in MCF-10A cells following exposure to chronic or acute ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Manesh, Sara Shakeri; Sangsuwan, Traimate; Wojcik, Andrzej; Haghdoost, Siamak, E-mail: Siamak.haghdoost@su.se

    2015-10-15

    Highlights: • 50 mGy at 1.4 mGy/h induces adaptive response in MCF-10A at mutation level. • Low dose rate γ-radiation does not induce adaptive response at survival level. • Overall, a dose rate effect is absent at the level of mutation in MCF-10A cells. - Abstract: A phenomenon in which exposure to a low adapting dose of radiation makes cells more resistant to the effects of a subsequent high dose exposure is termed radio-adaptive response. Adaptive response could hypothetically reduce the risk of late adverse effects of chronic or acute radiation exposures in humans. Understanding the underlying mechanisms of such responses is of relevance for radiation protection as well as for the clinical applications of radiation in medicine. However, due to the variability of responses depending on the model system and radiation condition, there is a need to further study under what conditions adaptive response can be induced. In this study, we analyzed if there is a dose rate dependence for the adapting dose, assuming that the adapting dose induces DNA response/repair pathways that are dose rate dependent. MCF-10A cells were exposed to a 50 mGy adapting dose administered acutely (0.40 Gy/min) or chronically (1.4 mGy/h or 4.1 mGy/h) and then irradiated by high acute challenging doses. The endpoints of study include clonogenic cell survival and mutation frequency at X-linked hprt locus. In another series of experiment, cells were exposed to 100 mGy and 1 Gy at different dose rates (acutely and chronically) and then the mutation frequencies were studied. Adaptive response was absent at the level of clonogenic survival. The mutation frequencies were significantly decreased in the cells pre-exposed to 50 mGy at 1.4 mGy/h followed by 1 Gy acute exposure as challenging dose. Importantly, at single dose exposures (1 Gy or 100 mGy), no differences at the level of mutation were found comparing different dose rates.

  16. Effects of a chromosome-3 mutator gene on radiation-induced mutability in Drosophila melanogaster females

    Energy Technology Data Exchange (ETDEWEB)

    Sankaranarayanan, K. (Rijksuniversiteit Leiden (Netherlands). Dept. of Radiation Genetics and Chemical Mutagenesis; Cohen (J.A.) Inst. voor Radiopathologie en Stralenbescherming, Leiden (Netherlands))

    1982-01-01

    A series of X-irradiation experiments was carried out using Drosophila melanogaster females homozygous for a third chromosome mutator gene and females which had a similar genetic background except that the mutator-bearing third chromosomes were substituted by normal wild-type chromosomes. In the present work, the sensitivity of the pre-meiotic germ cells of mutator and normal females to the X-ray induction (2000 R) of sex-linked recessive lethals was studied. In addition, experiments were conducted to examine the sensitivity of the immature (stage 7; prophase I of meiosis) oocytes of both kinds of females to the induction of dominant lethals, X-linked recessive lethals and X-chromosome losses. The results show that in pre-meiotic germ cells, the frequencies of radiation-induced recessive lethals are similar in both kinds of females. However, the proportion of these mutations that occur in clusters of size 3 and higher, is higher in mutator than in normal females. In stage-7 oocytes, the frequencies of radiation-induced dominant lethals and sex-linked recessive lethals were similar in both kinds of females. The X-loss frequencies however, were consistently higher in mutator females although statistical significance was obtained only at higher exposures (3000 and 3750 R) and not at lower ones (750-2250 R). Possible reasons for the discrepancy between the present results and those of Gold and Green with respect to pre-meiotic germ cells are discussed.

  17. The effects of MSH2 deficiency on spontaneous and radiation-induced mutation rates in the mouse germline

    International Nuclear Information System (INIS)

    Burr, Karen L-A.; Duyn-Goedhart, Annemarie van; Hickenbotham, Peter; Monger, Karen; Buul, Paul P.W. van; Dubrova, Yuri E.

    2007-01-01

    Mutation rates at two expanded simple tandem repeat (ESTR) loci were studied in the germline of mismatch repair deficient Msh2 knock-out mice. Spontaneous mutation rates in homozygous Msh2 -/- males were significantly higher than those in isogenic wild-type (Msh2 +/+ ) and heterozygous (Msh2 +/- ) mice. In contrast, the irradiated Msh2 -/- mice did not show any detectable increases in their mutation rate, whereas significant ESTR mutation induction was observed in the irradiated Msh2 +/+ and Msh2 +/- animals. Considering these data and the results of other publications, we propose that the Msh2-deficient mice possess a mutator phenotype in their germline and somatic tissues while the loss of a single Msh2 allele does not affect the stability of heterozygotes

  18. Radiation-induced mutagenicity and lethality in Ames tester strains of Salmonella

    International Nuclear Information System (INIS)

    Isildar, M.; Bakale, G.

    1984-01-01

    Mutation and killing induced by X radiation and 60 Co γ radiation were studied in six different histidine-requiring auxotrophs of Salmonella typhimurium. Strain TA100, which is sensitive to base-pair substitutions, and strains TA2637 and TA98, which are sensitive to frameshifts, carry the pKM101 plasmid and exhibit significantly higher radiation-induced mutations compared to their plasmidless parent strains TA1535, TA1537, and TA1538, respectively. Among the plasmid-containing strains, TA98 and TA2637 are much more sensitive to the mutagenic action of radiation than is TA100 based on a comparison with their respective spontaneous mutation rates; however, no uniformity was observed in the responses of the strains to the lethal action of ionizing radiation. The following conclusions are consistent with these observations: (1) the standard Ames Salmonella assay correctly identifies ionizing radiation as a mutagenic agent; (2) frameshift-sensitive parent strains are more sensitive to the mutagenic effects of ionizing radiation than is the only strain studied that is sensitive to base-pair substitutions; and (3) enhancement of mutagenesis and survival is related to plasmid-mediated repair of DNA damage induced by ionizing radiation and does not involve damage induced by Cerenkov-generated uv radiation which is negligible for our irradiation conditions

  19. Dose rate effectiveness in radiation-induced teratogenesis in mice

    International Nuclear Information System (INIS)

    Kato, F.; Ootsuyama, A.; Norimura, T.

    2000-01-01

    To investigate the role of p53 gene in tissue repair of teratogenic injury, we compared incidence of radiation-induced malformations in homozygous p53(-/-) mice, heterozygous p53(+/-) mice and wild-type p53(+/+) mice. After X-irradiation with 2 Gy at high dose rate on 9.5 days of gestation, p53(-/-) mice showed higher incidences of anomalies and higher resistance to prenatal deaths than p53(+/+) mice. This reciprocal relationship of radiosensitivity to anomalies and deaths supports the notion that embryos or fetuses have a p53-dependent 'guardian' that aborts cells bearing radiation-induced teratogenic DNA damage. In fact, after X-irradiation, the number of apoptotic cells was greatly increased in p53(+/+) fetuses but not in p53(-/-) fetuses. The same dose of γ-ray exposure at low dose rate on 9.5-10.5 day of gestation produced significant reduction of radiation-induced malformation in p53(+/+) and p53(+/-) mice, remained teratogenic for p53(-/-) mice. These results suggest that complete elimination of teratogenic damage from irradiated tissues requires the concerted cooperation of two mechanisms; proficient DNA repair and the p53-dependent apoptotic tissue repair. When concerted DNA repair and apoptosis functions efficiently, there is a threshold dose-rate for radiation-induced malformations. (author)

  20. Utilization of radiations in mutation breeding of tuber crops

    International Nuclear Information System (INIS)

    Kukimura, H.

    1981-01-01

    Most of the tuber crops are vegetatively propagated and their spontaneous mutations have been constructively utilized to practical farming. Significance of utilization of mutations to breeding should not be overlooked, since mutation can be articially induced by various mutagenic agents. In tuber crops, ionizing radiations are mostly applied to induce mutations. Radiosensitivity varies with species, genotypes and organs. For the purpose of mutation induction, 10-20 kR of gamma-rays is given to tubers and/or shoots in sweet potato and 2-10 kR in potato. It should be noted that radiation damage is more or less transmissible to later vegetative generations. A useful characters in practical agriculture, following mutations have been obtained so far: skin colour, short stemmed, changes in dry matter content, total sugars content and tuber yield, earlier maturity and sculf resistance in sweet potato. And, skin colour, changes in starch content and stolon length, day-neutral tuberization and cyst-nematode resistance in potato. Apart from mutations, radiation can be utilized for breaking down the incompatibility in sweet potato. Promising mutant clones with probable release in Japan are Kyushu 78 of sweet potato and Koniku 16 and Konkei 55 of potato. (author)

  1. Mutations induced by X-rays and UV radiation during the nuclear cycle in the yeast Schizosarccharomyces pombe

    International Nuclear Information System (INIS)

    Barale, R.; Rusciano, D.; Loprieno, N.

    1982-01-01

    The availability of a cell-division-cycle (cdc) mutant in the fission yeast S. pombe, wee 1-50, has made possible the production of a large population of G 1 nuclear-stage synchronized cells. During their development, yeast cells from the G 1 into the G 2 nuclear stages were treated with X-rays and UV radiation at various doses. The DNA pre-replicative and replicative phases were the most sensitive to both cell lethality and mutant induction with either X-rays or UV radiation. The trends of induced biological effects that were observed suggest that the induction of mutations is dependent on the number of unrepaired DNA lesions that reach the replicating fork or of those that occur at that time. The X-ray-induced mutations were earlier saturated, possibly because of the higher number of lethal lesions so induced. (orig.)

  2. Crop improvement by using radiation mutation breeding in Korea

    International Nuclear Information System (INIS)

    Lee, Young IL

    1998-01-01

    For crop improvement by the application of radiation technology, induction of mutants by in vivo and in vitro mutagenesis were developed in various crop plants in Korea. Several mutants have been released as recommended cultivars to farmers in rice, soybean, sesame and barley since 1970. Induced mutations were widely used for the introduction of genetic transformation and extending plant genetic resources. High yield, short plant, earliness, resistance to diseases, high protein and oil contents were obtained in the advanced generation of mutation by radiation application to several crops of in vivo and in vitro cultured materials. For induction and selection of promising mutants by in vivo and in vitro mutagenesis, various crops were successively irradiated with radiation to investigate the radiosensitivities, the mutation spectrum and mutation rate for selection of useful mutants. Plant tissue culture methods were developed for in vitro mutagenesis in the seed and the vegetatively propagating crops. Embryogenic callus was obtained from shoot tip culture of sweet potato, and micro propagation was developed from nodal stem culture of potato. The radiosensitivities were investigated in cell, callus, and in vitro plant lets. About 800 lines of mutants were evaluated for the agro-genetic resources. (author). 19 refs., 5 tabs

  3. Mutation induction by and mutational interaction between monochromatic wavelength radiations in the near-ultraviolet and visible ranges

    International Nuclear Information System (INIS)

    Tyrrell, R.M.

    1980-01-01

    The induction of mutations (reversion to tryptophan independence) by various UV (254, 313, 334 and 365 nm) and visible (405 and 434 nm) wavelengths was measured in exponential phase populations of Escherichia coli B/r thy trp and B/r thy trp uvr A by assay of irradiated populations on semi-enriched media. No mutations were induced in the repair proficient strain at wavelengths longer than 313 nm. Mutations were induced to the excisionless strain at wavelengths as long as 405 nm but less than expected from the known amount of DNA damage induced. Irradiation at the long wavelenths (434, 405, 365 and 334 nm) suppressed the appearance of 254- or 313 nm-induced mutations in the repair competent strain but not in the excision deficient strain. The relative dose-requirement for mutation suppression was related to the relative efficiency of these wavelengths in inducing growth delay. These results suggest that the growth delay induced by near-UV and visible wavelenghts allows more time for the 'error-free' excision repair process to act on the potentially mutagenic lesions induced by 254- and 313-nm radiations, thereby reducing the mutation frequency observed in the repair-proficient strain. The level of near-UV mutation induced in the excision deficient strain is lower than expected from the DNA damage known to be induced. It is possible that near-UV radiation induces a class of lethal lesions that are not susceptible to error-prone repair. (author)

  4. Use of gamma radiation in floriculture industry for development of new varieties through induced mutation

    International Nuclear Information System (INIS)

    Datta, S.K.

    2002-01-01

    Nuclear radiation (gamma rays) can create changes in genetic make up of plant material through mutation. Gamma ray induced mutation is now an established method for crop improvement. It is well known that the crops which are propagated vegetatively are very suitable for the application of mutation breeding methods. In floriculture industry there is always demand and necessity of new and novel ornamental varieties. Flower colour and shape are the most important components of novelties. Gamma rays have been most successfully use to produce quite a large number of new promising,varieties in different ornamental (Bougainvillea - 4, Perennial portulaca-6, Chrysanthemum-43, Hibiscus-1, Rose-16, Tuberose-2, Lantana depressa-3 etc.) plants by bringing about genetic changes at Floriculture Section, National Botanical Research. Institute, Lucknow, India. Research carried out covers radiosensitivity, selection of materials, methods of exposure to gamma rays, suitable dose of gamma rays, detection of mutants, isolation of mutants and commercial exploitation of mutants. A good number of mutant varieties have been well accepted in the floriculture industry. The mutant varieties are with new flower colour and shape. More than three decades of applied mutation breeding work has now established beyond doubt that mutation breeding will constitute an excellent supplement to the conventional methods for development of new varieties . Detection of somatic, mutations in flower colour/shape in different vegetative generations (M 1 V 1 , M 1 V 2 , M 1 V 3 and even in later vegetative generations), mutation frequency and spectrum relationship with dose of gamma radiation have been precisely determined. Studies have clearly proved that mutation breeding technique can be exploited for the creation of new and novel ornamental cultivars of commercial importance by inducing genetic variation in already adapted, modern genotypes and can also enrich the germplasm of ornamental horticulture

  5. Deficiency of the DNA repair protein nibrin increases the basal but not the radiation induced mutation frequency in vivo

    International Nuclear Information System (INIS)

    Wessendorf, Petra; Vijg, Jan; Nussenzweig, André; Digweed, Martin

    2014-01-01

    Highlights: • lacZ mutant frequencies measured in vivo in mouse models of radiosensitive Nijmegen Breakage Syndrome. • Spontaneous mutation frequencies are increased in lymphatic tissue due to Nbn mutation. • Single base transitions, not deletions, dominate the mutation spectrum. • Radiation induced mutation frequencies are not increased due to Nbn mutation. - Abstract: Nibrin (NBN) is a member of a DNA repair complex together with MRE11 and RAD50. The complex is associated particularly with the repair of DNA double strand breaks and with the regulation of cell cycle check points. Hypomorphic mutation of components of the complex leads to human disorders characterised by radiosensitivity and increased tumour occurrence, particularly of the lymphatic system. We have examined here the relationship between DNA damage, mutation frequency and mutation spectrum in vitro and in vivo in mouse models carrying NBN mutations and a lacZ reporter plasmid. We find that NBN mutation leads to increased spontaneous DNA damage in fibroblasts in vitro and high basal mutation rates in lymphatic tissue of mice in vivo. The characteristic mutation spectrum is dominated by single base transitions rather than the deletions and complex rearrangements expected after abortive repair of DNA double strand breaks. We conclude that in the absence of wild type nibrin, the repair of spontaneous errors, presumably arising during DNA replication, makes a major contribution to the basal mutation rate. This applies also to cells heterozygous for an NBN null mutation. Mutation frequencies after irradiation in vivo were not increased in mice with nibrin mutations as might have been expected considering the radiosensitivity of NBS patient cells in vitro. Evidently apoptosis is efficient, even in the absence of wild type nibrin

  6. Deficiency of the DNA repair protein nibrin increases the basal but not the radiation induced mutation frequency in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Wessendorf, Petra [Institute of Medical and Human Genetics, Charité – Universitätsmedizin Berlin, Augustenburger Platz 1, D-13353 Berlin (Germany); Vijg, Jan [Albert Einstein College of Medicine, Michael F. Price Center, 1301 Morris Park Avenue, Bronx, NY 10461 (United States); Nussenzweig, André [Laboratory of Genome Integrity, National Cancer Institute, National Institute of Health, 37 Convent Drive, Room 1106, Bethesda, MD 20892 (United States); Digweed, Martin, E-mail: martin.digweed@charite.de [Institute of Medical and Human Genetics, Charité – Universitätsmedizin Berlin, Augustenburger Platz 1, D-13353 Berlin (Germany)

    2014-11-15

    Highlights: • lacZ mutant frequencies measured in vivo in mouse models of radiosensitive Nijmegen Breakage Syndrome. • Spontaneous mutation frequencies are increased in lymphatic tissue due to Nbn mutation. • Single base transitions, not deletions, dominate the mutation spectrum. • Radiation induced mutation frequencies are not increased due to Nbn mutation. - Abstract: Nibrin (NBN) is a member of a DNA repair complex together with MRE11 and RAD50. The complex is associated particularly with the repair of DNA double strand breaks and with the regulation of cell cycle check points. Hypomorphic mutation of components of the complex leads to human disorders characterised by radiosensitivity and increased tumour occurrence, particularly of the lymphatic system. We have examined here the relationship between DNA damage, mutation frequency and mutation spectrum in vitro and in vivo in mouse models carrying NBN mutations and a lacZ reporter plasmid. We find that NBN mutation leads to increased spontaneous DNA damage in fibroblasts in vitro and high basal mutation rates in lymphatic tissue of mice in vivo. The characteristic mutation spectrum is dominated by single base transitions rather than the deletions and complex rearrangements expected after abortive repair of DNA double strand breaks. We conclude that in the absence of wild type nibrin, the repair of spontaneous errors, presumably arising during DNA replication, makes a major contribution to the basal mutation rate. This applies also to cells heterozygous for an NBN null mutation. Mutation frequencies after irradiation in vivo were not increased in mice with nibrin mutations as might have been expected considering the radiosensitivity of NBS patient cells in vitro. Evidently apoptosis is efficient, even in the absence of wild type nibrin.

  7. Molecular biology methods in assessing radiation-induced hereditary risks in humans

    International Nuclear Information System (INIS)

    Kiuru, A.

    2004-12-01

    Effort to predict the genetic consequences for humans of exposure to ionising radiation has been one of the most important issues of human genetics over the past 60 years. To date, there has been little experimental knowledge on the genetic risks of human exposure to ionising radiation. Radiation-induced deleterious hereditary effects have not been detected in human populations - not even among the offspring of atomic bomb survivors in Hiroshima and Nagasaki. This does not mean deleterious hereditary effects do not exist in humans, but rather that they are small and/or difficult to detect because the normal incidence of inherited abnormalities is quite high in the human population. Thus, assessment of radiation-induced hereditary risks in humans has been based on the common knowledge of human heredity and on animal experiments. However, recent data have suggested that hyper-variable tandem repeat minisatellite loci provide a useful and sensitive experimental approach for monitoring radiation-induced germline mutations in humans. In order to investigate the feasibility of the minisatellite mutation screening system in assessing radiation-induced hereditary risks in humans, we examined the amount of hereditary minisatellite mutations among the offspring of Estonian Chernobyl cleanup workers. The men studied received a median radiation dose of 109 mSv while working on the cleanup activities after the Chernobyl accident. We compared the minisatellite mutation rates of 155 children born to 147 Estonian Chernobyl cleanup workers after the accident to those of their 148 siblings born prior to it. In addition, 44 Estonian families, where the father had not been exposed to radiation, composed an additional control group. In all of these families, the paternity of the children was ascertained by using 5 minisatellite loci (APOB, HRAS, MCOB19, MCT118, and YNZ-22) in PCR-based analyses. Other 8 minisatellite loci (B6.7, CEB1, CEB15, CEB25, CEB36, MS1, MS31, and MS32) were used

  8. Rice improvement through radiation-induced mutation for cultivation in South Vietnam

    International Nuclear Information System (INIS)

    Do Khac Thinh; Hung Phi Oanh; Nguyen Thi Cuc; Nguyen Ngoc Quynh

    2001-01-01

    For past years, rice varieties cultivated in South Vietnam originated from domestic hybridisation or from IRRI. Rice mutation breeding has been initiated for recent years. To meet the requirement of rice production diversification in different agro-ecological areas and rice genetic resources, from 1993 Institute of Agricultural Science of South Vietnam has carried out rice improvement by induced mutation of radiation. The mutagen was gamma rays of 60 Co. The goal is to create inherited variations, which cannot be obtained from other breeding methods, specially important characters of rice varieties (high tolerance to acid sulfate soil, lodging resistance combined with early maturity), which were difficult to gain by hybridisation. With 60 Co gamma rays, doses of 10-20 krad, dose rate of 280 krad/h, dry and germinated seeds of introduced and local rice varieties (IR 64, IR 9729, IR 50404, IR 59606, Jasmine 85, Nang Huong, Tam Xoan) were irradiated. The irradiated seeds were immediately sown within 24 and 94 hrs for wet seeds and dry seeds after treatment, respectively. Population of 10,000-15,000 plants were established and evaluated by IRRI evaluation standard from M2-M7 generations. 365 lines, varieties were selected with better behaviours than original varieties as lodging resistance, earliness, potential yield, leaf characters, tolerant ability to adverse conditions etc. Some good varieties (VND95-19, VND95-20) have been approved as leading national varieties and released for large-scale production in South Vietnam. (author)

  9. Rice improvement through radiation-induced mutation for cultivation in South Vietnam

    Energy Technology Data Exchange (ETDEWEB)

    Do Khac Thinh; Hung Phi Oanh; Nguyen Thi Cuc; Nguyen Ngoc Quynh [Institute of Agricultural Science of South Vietnam, Ho Chi Minh (Viet Nam)

    2001-03-01

    For past years, rice varieties cultivated in South Vietnam originated from domestic hybridisation or from IRRI. Rice mutation breeding has been initiated for recent years. To meet the requirement of rice production diversification in different agro-ecological areas and rice genetic resources, from 1993 Institute of Agricultural Science of South Vietnam has carried out rice improvement by induced mutation of radiation. The mutagen was gamma rays of {sup 60}Co. The goal is to create inherited variations, which cannot be obtained from other breeding methods, specially important characters of rice varieties (high tolerance to acid sulfate soil, lodging resistance combined with early maturity), which were difficult to gain by hybridisation. With {sup 60}Co gamma rays, doses of 10-20 krad, dose rate of 280 krad/h, dry and germinated seeds of introduced and local rice varieties (IR 64, IR 9729, IR 50404, IR 59606, Jasmine 85, Nang Huong, Tam Xoan) were irradiated. The irradiated seeds were immediately sown within 24 and 94 hrs for wet seeds and dry seeds after treatment, respectively. Population of 10,000-15,000 plants were established and evaluated by IRRI evaluation standard from M2-M7 generations. 365 lines, varieties were selected with better behaviours than original varieties as lodging resistance, earliness, potential yield, leaf characters, tolerant ability to adverse conditions etc. Some good varieties (VND95-19, VND95-20) have been approved as leading national varieties and released for large-scale production in South Vietnam. (author)

  10. Genetic influence of radiation measured by the effect on the mutation rate of human minisatellite genes

    International Nuclear Information System (INIS)

    Kodaira, Mieko

    2002-01-01

    Human minisatellite genes are composed from 0.1-30 kb with a high frequency of polymorphism. The genes exist in mammalian genomes and mice's ones are well studied after irradiation of their gonad cells by X-ray and γ-ray. Following five reports concerning the significant and/or insignificant increases of the mutation rate of the genes post A-bomb exposure, Chernobyl accident and nuclear weapons test in Semipalatinsk are reviewed and discussed on the subject number, exposed dose, problems of the control group, regions examined of loci and exposure conditions. Genetic influences of radiation examined by the author's facility are not recognized in the mutation rate (3.21% vs 4.94% in the control) of minisatellite genes in children of A-bomb survivors and their parents. The mutation rates are 4.27 vs 2.52% (positive influence) and 4.2-6.01% vs 3.5-6.34% in Chernobyl, and 4.3 (parents) and 3.8% (F 1 ) vs 2.5% (positive). Mutation of human minisatellite genes can be an important measure of genetic influences at the medical level. (K.H.)

  11. The role of radiation induced mutations in crop Improvement

    International Nuclear Information System (INIS)

    Souframanien, J.

    2017-01-01

    Sudden, heritable changes in the genetic material, DNA, are known as mutations. Selection of naturally occurring mutations in wild, ancestral species helped humans in the domestication and further improvement of today's crop plants. Gregor Mendel in 1865 used several such natural mutants in his experiments with garden pea to formulate the laws of inheritance. The term mutation itself was used for the first time by Hugo de Vries in 1901 in his mutation theory. Plant breeding based on the science of genetics, as practiced over the past 100 years, exploited the available genetic variability in the primary gene pool of crop plants, and sometimes in related species. Primarily, simple selection of desirable offspring and cross breeding were the earlier methods of breeding and this utilized the occurrence of spontaneous mutations. In nature, occurrence of natural variability in the form of spontaneous mutations is extremely low (about 10 -6 ), which can be enhanced several fold (∼10 -3 ) by using ionizing radiations or chemical mutagens

  12. RFLP analysis of rice semi-dwarf mutation induced by high energy argon ion radiation

    International Nuclear Information System (INIS)

    Zhuang Chuxiong; Hu Weimin; Mei Mantong

    1997-01-01

    Two Indica rice varieties, Bianpizhan and Xiangzhan, and their semi-dwarf mutants induced by high energy argon ion radiation, Ar-10, and Xiang-Ar-1, were examined with restriction fragment length polymorphism (RFLP) analysis by using 97 rice single copy genomic clones mapped on 12 chromosomes of molecular genetic map, combined with 5 restriction enzymes. Among the markers screened, 9 detected polymorphism were between Bianpizhen and Ar-10, and 11 detected polymorphism were between Xiangzhan and Xiang-Ar-1. Moreover, two or more restriction enzymes could generate RFLP patterns when screened with a given marker for several polymorphic markers. Based on the polymorphic allelic loci, the mutation frequencies were estimated as 5.15% and 6.39% for Ar-10 and Xiang-Ar-1 respectively. These results suggested that the nature of mutation on the DNA level was probably large genetic changes rather than point mutation. Genetic analysis and gene tagging of semi-dwarf mutation in one of the mutant line, Ar-10, indicated that this mutation was controlled by a major recessive gene, which was preliminary located on chromosome 4

  13. RFLP Analysis of rice semi dwarf mutation induced by high energy argon ion radiation

    International Nuclear Information System (INIS)

    Zhuang Chuxiong; Hu Weimin; Mei Mantong

    1997-01-01

    Two Indica rice varieties, Bianpizhan and Xiangzhan, and their semi dwarf mutants induced by high energy argon ion radiation, Ar 10, and Xiang Ar 1, were examined with restriction fragment length polymorphism(RFLP)analysis by using 97 rice single copy genomic clones mapped on 12 chromosomes of molecular genetic map, combined with 5 restriction enzymes.Among the markers screened, 9 detected polymorphism were between Bianpizhan and Ar 10, and 11 detected polymorphism were between Xiangzhan and Xiang Ar 1.Moreover, two or more restriction enzymes could generate RFLP patterns when screened with a given marker for several polymorphic markers. Based on the polymorphic allelic loci, the mutation frequencies were estimated as 5 15% and 6 39% for Ar 10 and Xiang Ar 1 respectively.These results suggested that the nature of mutation on the DNA level was probably large genetic changes rather than point mutation.Genetic analysis and gene tagging of semi dwarf mutation in one of the mutant line, Ar 10, indicated that this mutation was controlled by a major recessive gene, which was preliminary located on chromosome 4. (author)

  14. Radiation-induced transgenerational instability.

    Science.gov (United States)

    Dubrova, Yuri E

    2003-10-13

    To date, the analysis of mutation induction has provided an irrefutable evidence for an elevated germline mutation rate in the parents directly exposed to ionizing radiation and a number of chemical mutagens. However, the results of numerous publications suggest that radiation may also have an indirect effect on genome stability, which is transmitted through the germ line of irradiated parents to their offspring. This review describes the phenomenon of transgenerational instability and focuses on the data showing increased cancer incidence and elevated mutation rates in the germ line and somatic tissues of the offspring of irradiated parents. The possible mechanisms of transgenerational instability are also discussed.

  15. Induced mutations - a tool in plant research

    International Nuclear Information System (INIS)

    1981-01-01

    These proceedings include 34 papers and 18 brief descriptions of poster presentations in the following areas as they are affected by induced mutations: advancement of genetics, plant evolution, plant physiology, plant parasites, plant symbioses, in vitro culture, gene ecology and plant breeding. Only a relatively small number of papers are of direct nuclear interest essentially in view of the mutations being induced by ionizing radiations. The papers of nuclear interest have been entered as separate and individual items of input

  16. Plant Breeding by Using Radiation Mutation

    International Nuclear Information System (INIS)

    Kang, Si Yong; Kim, Dong Sub; Lee, Geung Joo

    2007-06-01

    A mutation breeding is to use physical or chemical mutagens to induce mutagenesis, followed by individual selections with favorable traits. The mutation breeding has many advantages over other breeding methods, which include the usefulness for improving one or two inferior characteristics, applications to broad species with different reproductive systems or to diverse plant materials, native or plant introduction with narrow genetic background, time and cost-effectiveness, and valuable mutant resources for genomic researches. Recent applications of the radiation breeding techniques to developments of flowering plants or food crops with improved functional constituents heightened the public's interests in agriculture and in our genetic resources and seed industries. The goals of this project, therefore, include achieving advances in domestic seed industries and agricultural productivities by developing and using new radiation mutants with favored traits, protecting an intellectual property right of domestic seeds or germplasm, and sharing the valuable mutants and mutated gene information for the genomic and biotech researches that eventually leads to economic benefits

  17. Plant Breeding by Using Radiation Mutation

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Si Yong; Kim, Dong Sub; Lee, Geung Joo (and others)

    2007-06-15

    A mutation breeding is to use physical or chemical mutagens to induce mutagenesis, followed by individual selections with favorable traits. The mutation breeding has many advantages over other breeding methods, which include the usefulness for improving one or two inferior characteristics, applications to broad species with different reproductive systems or to diverse plant materials, native or plant introduction with narrow genetic background, time and cost-effectiveness, and valuable mutant resources for genomic researches. Recent applications of the radiation breeding techniques to developments of flowering plants or food crops with improved functional constituents heightened the public's interests in agriculture and in our genetic resources and seed industries. The goals of this project, therefore, include achieving advances in domestic seed industries and agricultural productivities by developing and using new radiation mutants with favored traits, protecting an intellectual property right of domestic seeds or germplasm, and sharing the valuable mutants and mutated gene information for the genomic and biotech researches that eventually leads to economic benefits.

  18. HPRT gene locus mutation in peripheral blood lymphocytes induced by internal exposure to radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Jingyong, Zhao; Yongzhong, Xu; Tao, Zhao; Fengmei, Cui; Liuyi, Wang; Qinhua, Lao [Suzhou Univ., Suzhou (China). Radiation Medicine Department

    2001-07-01

    HPRT gene locus mutation in peripheral blood lymphocytes induced by internal exposure to radionuclides was performed and the relationships between mutation frequency and dose were studied. Rats were injected intravenously with radionuclides, the blood was sampled at different time after injection; HPRT gene locus mutation frequency (GMF) were examined by methods of multi-nucleus cell and Brdurd assay, working out the Dose-response function. GMF rose with the increase of dose and dose-rates and were clearly interrelated. The HPRT gene locus mutation is very sensitive to radiation and may be used as a biological dosimeter.

  19. Ionizing radiation induced malignancies in man

    International Nuclear Information System (INIS)

    Dutrillaux, B.

    1997-01-01

    Using data on gene and chromosome alterations in human cancers, it is proposed that most radiation induced cancers are a consequence of recessive mutations of tumor suppressor genes. This explains the long delay between radiation exposure and the cancer onset. As a consequence, radiation induced cancers belong to groups of tumors where no specific translocations (forming or activating oncogenes) but multiple unbalanced chromosome rearrangements (deletions unmasking recessive mutations) exist. This explains why osteosarcomas, malignant fibrous histiocytoma, chondrosarcomas are frequently induced, but not liposarcoma, Ewing sarcomas and rhabdomyosarcomas, among others. A single exception confirms this rule: papillary thyroid cancer, frequently induced in exposed children, in which structural rearrangements frequently form a RET/PTC3 fusion gene. This fusion gene is the results of the inversion of a short segment of chromosome 10, and it is assumed that such rearrangement (small para-centric inversion) can easily occur after exposure to radiations, at contrast with translocations between to genes belonging to different chromosomes. (author)

  20. Estimation of mutation rates induced by large doses of gamma, proton and neutron irradiation of the X-chromosome of the nematode Panagrellus redivivus

    International Nuclear Information System (INIS)

    Denich, K.T.R.; Samoiloff, M.R.

    1984-01-01

    The radiation-resistant free-living nematode Panagrellus redivivus was used to study mutation rates in oocytes, following gamma, proton and neutron irradiation in the dose range 45-225 grays. γ-Radiation produced approximately 0.001 lethal X-chromosomes per gray over the range tested. Proton or neutron irradiation produced approximately 0.003 lethal X-chromosomes per gray at lower doses, with the mutation rate dropping to 0.001 lethal X-chromosome per gray at the higher doses. These results suggest a dose-dependent mutation-repair system. Cell lethality was also examined. γ-Radiation produced the greatest amount of cell lethality at all doses, while neutron irradiation had no cell lethal effect at any of the doses examined. (orig.)

  1. Coordinated Changes in Mutation and Growth Rates Induced by Genome Reduction

    Directory of Open Access Journals (Sweden)

    Issei Nishimura

    2017-07-01

    Full Text Available Genome size is determined during evolution, but it can also be altered by genetic engineering in laboratories. The systematic characterization of reduced genomes provides valuable insights into the cellular properties that are quantitatively described by the global parameters related to the dynamics of growth and mutation. In the present study, we analyzed a small collection of W3110 Escherichia coli derivatives containing either the wild-type genome or reduced genomes of various lengths to examine whether the mutation rate, a global parameter representing genomic plasticity, was affected by genome reduction. We found that the mutation rates of these cells increased with genome reduction. The correlation between genome length and mutation rate, which has been reported for the evolution of bacteria, was also identified, intriguingly, for genome reduction. Gene function enrichment analysis indicated that the deletion of many of the genes encoding membrane and transport proteins play a role in the mutation rate changes mediated by genome reduction. Furthermore, the increase in the mutation rate with genome reduction was highly associated with a decrease in the growth rate in a nutrition-dependent manner; thus, poorer media showed a larger change that was of higher significance. This negative correlation was strongly supported by experimental evidence that the serial transfer of the reduced genome improved the growth rate and reduced the mutation rate to a large extent. Taken together, the global parameters corresponding to the genome, growth, and mutation showed a coordinated relationship, which might be an essential working principle for balancing the cellular dynamics appropriate to the environment.

  2. Comparison of somatic mutation frequencies at HGPRT locus induced by radiation and chemical pollutant from energy system

    International Nuclear Information System (INIS)

    Xu Honglan; Cao Yi; Duan Zhikai; Wu Qiqing; Chen Ying; Zhang Shuxian

    1998-12-01

    The somatic induction frequencies of mutation at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus induced by 60 Co γ-rays and Benzo-a-pyrene (B(a)P), which are representative of hazardous emission and pollutant from nuclear energy cycle and fossil-fuelled energy cycle respectively, were detected by using forward mutation assay and cloning technique in both V 79 Chinese hamster cells and human peripheral blood T-lymphocytes. Resistant mutants were selected with 6-thioguanine (6-TG). Dose-response curves and mathematical expressions were obtained for mutation frequencies and survival following γ-ray and B(a)P(+S 9 ) treatments. The dose ranges for the two mutagens were compared when they induced the same mutation frequencies. In V 79 /HGPRT assay system, when the mutation frequencies were 5∼35 mutants/10 6 cells the response of γ-rays in the dose range from 0.93∼4.96 Gy at dose rate of 1.16 Gy/min is nearly equivalent to that in the B(a)P dose range from 0.52∼4.27 μg/ml. By using cloning technique in T-lymphocytes, when the mutation frequencies were 1∼14 mutants/10 5 cells the response of γ-rays in the dose range from 0.05∼4.77 Gy at dose rate of 1.03 Gy/min is nearly equivalent to that in the B(a)P dose range from 0.15∼7.36 μg/ml. When the survival fraction is 37%, the mutation frequency induced by B(a)P is higher than that induced by 60 Co γ-rays

  3. Effect of genes controlling radiation sensitivity on chemically induced mutations in Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Prakash, L.

    1976-01-01

    The effect of 16 different genes (rad) conferring radiation sensitivity on chemically induced reversion in the yeast Saccharomyces cerevisiae was determined. The site of reversion used was a well-defined chain initiation mutant mapping in the structural gene coding for iso-1-cytochrome c. High doses of EMS and HNO 2 resulted in decreased reversion of cyc1-131 in rad6, rad9 and rad15 strains compared to the normal RAD + strains. In addition, rad52 greatly decreased EMS reversion of cyc1-131 but had no effect on HNO 2 -induced reversion; rad18, on the other hand, increased HNO 2 -induced reversion but did not alter EMS-induced reversion. When NQO was used as the mutagen, every rad gene tested, except for rad18, had an effect on reversion; rad6, rad9, rad15, rad17, rad18, rad22, rev1, rev2, and rev3 lowered NQO reversion while rad1, rad2, rad3, rad4, rad10, rad12, and rad16 increased it compared to the RAD + strain. The effect of rad genes on chemical mutagenesis is discussed in terms of their effect on uv mutagenesis. It is concluded that although the nature of the repair pathways may differ for uv- and chemically-induced mutations in yeast, a functional repair system is required for the induction of mutation by the chemical agents NQO, EMS, and HNO 2

  4. Genetic signatures from amplification profiles characterize DNA mutation in somatic and radiation-induced sports of chrysanthemum

    International Nuclear Information System (INIS)

    Trigiano, R.N.; Scott, M.C.; Caetano-Anolles, G.

    1998-01-01

    The chrysanthemum (Dendranthema grandiflora Tzvelev.) cultivars 'Dark Charm', 'Salmon Charm', 'Coral Charm' and 'Dark Bronze Charm' are either radiation-induced mutants or spontaneous sports of 'Charm' and constitute a family or series of plants that primarily differ in flower color. These cultivars, which were difficult to differentiate genetically by DNA amplification fingerprinting (DAF), were easily identified by using arbitrary signatures from amplification profiles (ASAP). Genomic DNA was first amplified with three standard octamer arbitrary primers, all of which produced monomorphic profiles. Products from each of these DNA fingerprints were subsequently reamplified using four minihairpin decamer primers. The 12 primer combinations produced signatures containing approximately 37% polymorphic character loci, which were used to estimate genetic relationships between cultivars. Forty-six (32%) unique amplification products were associated with individual cultivars. The number of ASAP polymorphisms detected provided an estimate of the mutation rate in the mutant cultivars, ranging from 0.03% to 1.6% of nucleotide changes within an average of 18 kb of arbitrary amplified DAF sequence. The ASAP technique permits the clear genetic identification of somatic mutants and radiation-induced sports that are genetically highly homogeneous and should facilitate marker assisted breeding and protection of plant breeders rights of varieties or cultivars

  5. Gene alterations in radiation-induced F344 rat lung tumors

    International Nuclear Information System (INIS)

    Kelly, G.; Hahn, F.F.

    1994-01-01

    The p53 tumor suppressor gene is frequently altered in all major histopathologic types of human lung tumors. Reported p53 mutations include base substitutions, allelic loss, rearrangements, and deletions. Point mutations resulting in base substitutions are clustered within a highly conserved region of the gene encoding exons 508, and mutations in this region substantially extend the half-life of the p53 protein. In addition to its prominent importance in lung carcinogenesis, the p53 gene plays a critical role in the cellular response to genetic damage caused by radiation. Specifically, the protein product of p53 induces a pause or block at the G 1 to S boundary of the cell cycle following radiation-caused DNA damage. This G 1 block may allow the cell time to repair the damaged DNA prior to replication. Cells lacking a functional p53 protein fail to pause for repair and consequently accumulate mutations in the genome at an accelerated rate. p53 has also been implicated as a controlling factor in apoptosis or in programmed cell death induced by DNA-damaging agents, such as ionizing radiation. The p53 gene is mutated in approximately 50% of squamous cell carcinomas from uranium miners who inhaled high doses of radon daughters. The purpose of the present study was to determine if a similar percentage of squamous cell carcinomas with p53 mutations developed in the lungs of rats exposed to aerosols of 239 PuO 2

  6. Genotoxic effects of high dose rate X-ray and low dose rate gamma radiation in ApcMin/+ mice.

    Science.gov (United States)

    Graupner, Anne; Eide, Dag M; Brede, Dag A; Ellender, Michele; Lindbo Hansen, Elisabeth; Oughton, Deborah H; Bouffler, Simon D; Brunborg, Gunnar; Olsen, Ann Karin

    2017-10-01

    Risk estimates for radiation-induced cancer in humans are based on epidemiological data largely drawn from the Japanese atomic bomb survivor studies, which received an acute high dose rate (HDR) ionising radiation. Limited knowledge exists about the effects of chronic low dose rate (LDR) exposure, particularly with respect to the application of the dose and dose rate effectiveness factor. As part of a study to investigate the development of colon cancer following chronic LDR vs. acute HDR radiation, this study presents the results of genotoxic effects in blood of exposed mice. CBAB6 F1 Apc +/+ (wild type) and Apc Min/+ mice were chronically exposed to estimated whole body absorbed doses of 1.7 or 3.2 Gy 60 Co-γ-rays at a LDR (2.2 mGy h -1 ) or acutely exposed to 2.6 Gy HDR X-rays (1.3 Gy min -1 ). Genotoxic endpoints assessed in blood included chromosomal damage (flow cytometry based micronuclei (MN) assay), mutation analyses (Pig-a gene mutation assay), and levels of DNA lesions (Comet assay, single-strand breaks (ssb), alkali labile sites (als), oxidized DNA bases). Ionising radiation (ca. 3 Gy) induced genotoxic effects dependent on the dose rate. Chromosomal aberrations (MN assay) increased 3- and 10-fold after chronic LDR and acute HDR, respectively. Phenotypic mutation frequencies as well as DNA lesions (ssb/als) were modulated after acute HDR but not after chronic LDR. The Apc Min/+ genotype did not influence the outcome in any of the investigated endpoints. The results herein will add to the scant data available on genotoxic effects following chronic LDR of ionising radiation. Environ. Mol. Mutagen. 58:560-569, 2017. © 2017 The Authors Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society. © 2017 The Authors Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.

  7. Identification of potential molecular markers of ionizing radiation-induced mutations at the hprt locus in CHO cells

    International Nuclear Information System (INIS)

    Schwartz, J.L.; Sun, J.; Porter, R.C.

    1995-01-01

    Using multiplex polymerase chain reaction-based exon deletion analysis, we have analyzed mutations at the hprt locus from independent CHO cell mutants isolated from untreated, 60 Co x-ray-, and 212 Bi-exposed CHO-K1 cello and its radiation-sensitive derivative, xrs-5. In the 71 spontaneous CHO-K1 mutants analyzed, 78% showed no change in exon number or size, 20% showed loss of 1-8 exons (partial deletion), and 3% showed loss of all nine hprt exons (total deletion). Exposure of CHO-K1 cells to 6 Gy of γ rays (10% survival) produced 45% of the 20 mutants analyzed showing partial deletion, and 30% showing total deletion. Exposure to an equitoxic dose of a radiation from 212 Bi, a 220 Rn daughter, resulted in a spectrum similar to the γ-ray spectrum in that more than 75% of the 49 mutants analyzed were deletions. The α-radiation, however, tended to produce larger intragenic deletions that γ radiation. Of the 87 spontaneous xrs-5 mutants analyzed for deletions 44% showed partial deletion, and 14% showed total deletion. Exposure to α radiation (10% survival) resulted in a deletion spectrum similar to that seen in CHO-K1 cells. Of the 49 mutants analyzed, 43% showed no change in exon number or size, 16% showed partial deletion, and 41% showed total deletion. While the defect in xrs-5 has a profound effect on spontaneous mutation spectra, it does not appear to affect α-induced mutation spectra

  8. Radiation-induced dominant skeletal mutations in mice: mutation rate, characteristics, and usefulness in estimating genetic hazard to humans from radiation

    International Nuclear Information System (INIS)

    Selby, P.B.

    1979-01-01

    The work discussed in this paper represents a major advance in the difficult task of trying to estimate the effects that an increase in mutation frequency would have on human health. Male mice were bred to three females prior to being killed and skeleton studies made. Guidelines were instituted for checking progeny mutations. Surprising results showed a mutation frequency of 1.4% per gamete where none would have been expected. It is now clear that mice can be greatly deformed without showing external effects

  9. Induced skeletal mutations

    International Nuclear Information System (INIS)

    Selby, P.B.

    1979-01-01

    This paper describes a large-scale experiment that, by means of breeding tests, confirmed that many dominant skeletal mutations are induced by large-dose radiation exposure. The author also discusses: (1) the major advantages and disadvantages of the skeletal method in improving estimates of genetic hazard to man; (2) future uses of the skeletal method; (3) direct estimation of risk beyond the first generation using the skeletal method; and (4) the possibility of using the skeletal method as a quick and easy screen for chemical mutagens

  10. Studies of human mutation rates, December 1, 1985--November 30, 1986

    International Nuclear Information System (INIS)

    Neel, J.V.

    1985-01-01

    This program seeks to quantify native human mutation rates and to determine how man's activities may affect these rates. The program is divided into six tasks, i.e. The American Indian mutation rate, monitoring populations for frequency of mutation by electrophoresis of blood proteins, application of molecular biological approaches to the detection and study of mutational events in human populations, development of two-dimensional electrophoresis for identification of mutant proteins, co-operative program with the Radiation Effects Research Foundation in Hiroshima and Nagasaki, Japan, and statistical problems associated with the estimation of mutation rates. Progress of each of the above tasks is related in detail. (DT)

  11. Manifestation of x-radiation induced sex-linked recessive lethal mutation impairing the development of imaginal disks and gonads in Drosophila Melanogaster

    International Nuclear Information System (INIS)

    Abeleva, Eh.A.; Ivanov, A.I.

    1982-01-01

    A study was made of Drosophila melanogaster mutations impairing the development of imaginal disks. The state of gonads in these mutants was not studied. Using X-radiation a lethal mutation in X chromosome was obtained that induced degeneration of imaginal disks at the 3d stage of larva development. The gonads of the mutants at this stage of development vary in size. The transplantation tests showed that the mutation manifests itself in both the imaginal disks and the gonads

  12. Effects of the umuC36 mutation on ultraviolet-radiation-induced base-change and frameshift mutations in Escherichia coli

    International Nuclear Information System (INIS)

    Kato, T.; Nakano, E.

    1981-01-01

    The effects of the umuC36 mutation on the induction of base-change and frameshift mutations were studied. An active umuC gene was necessary in either the uvr + or uvr - strains of Escherichia coli K12 for UV- and X-ray-induced mutations to His + , ColE and Spc, which are presumably base-change mutations, but it was not essential for ethyl methanesulphonate or N-methyl-N'-nitro-N-nitrosoguanidine-induced His + mutations. In contrast, only 1 out of 13 trp - frameshift mutations examined was UV reversible, and the process of mutagenesis was umuC + -dependent, whereas a potent frameshift mutagen, ICR191, effectively induced Trp + mutations in most of the strains regardless of the umu + or umuC genetic background. These results suggest that base substitutions are a major mutational type derived from the umuC + -dependent pathway of error-prone repair. (orig.)

  13. Genetic alterations during radiation-induced carcinogenesis

    International Nuclear Information System (INIS)

    Kodama, Seiji

    1995-01-01

    This paper reviews radiation-induced genetic alterations and its carcinogenesis, focusing on the previous in vitro assay outcome. A colony formation assay using Syrian hamster fetal cells and focus formation assay using mouse C3H10T1/2 cells are currently available to find malignant transformation of cells. Such in vitro assays has proposed the hypothesis that radiation-induced carcinogenesis arises from at least two-stage processes; i.e., that an early step induced by irradiation plays an important role in promoting the potential to cause the subsequent mutation. A type of genetic instability induced by radiation results in a persistently elevated frequency of spontaneous mutations, so-called the phenomenon of delayed reproductive death. One possible mechanism by which genetic instability arises has been shown to be due to the development of abnormality in the gene group involved in the maintenance mechanism of genome stability. Another possibility has also been shown to stem from the loss of telomere (the extremities of a chromosome). The importance of search for radiation-induced genetic instability is emphasized in view of the elucidation of carcinogenesis. (N.K.)

  14. Cellular repair and its importance for UV-induced mutations

    Energy Technology Data Exchange (ETDEWEB)

    Slamenova, D [Slovenska Akademia Vied, Bratislava (Czechoslovakia). Vyskumny Ustav Onkologicky

    1975-01-01

    Current knowledge is briefly surveyed of the mechanism of the biological repair of injuries induced in DNA cells by the action of various factors, mainly ultraviolet radiation. Genetic loci determining the sensitivity of cells to UV radiation are defined and principal reparation processes are explained; excision repair is described more fully. The role of biological repair is discussed in view of UV-induced mutations in DNA cells.

  15. Lethals induced by γ-radiation in drosophila somatic cells

    International Nuclear Information System (INIS)

    Ivanov, A.I.

    1989-01-01

    Exposure of 3-hour drosophila male embryos to γ-radiation during the topographic segregation of the germ anlage nuclei caused recessive sex-linked lethals in somatic cells only. The selectivity of the screening was determined by the ratio of mutation frequencies induced in embryos and adult males. Analysis of lethal mutations shows that a minimal rate of the divergence between germinal and somatic patterns of the cell development is observed in the embryogenesis, the 3d instar larva and prepupa, and maximal in the 1st and 2nd larva and pupa

  16. Ionizing radiation induced genomic instability and its relation to radiation carcinogenesis

    International Nuclear Information System (INIS)

    Wang Zhongwen

    2000-01-01

    There are widespread testimonies that the genomic instability induced by ionizing irradiation exits in mammal and its vitro cells. Genomic instability can enhance the frequency of genetic changes among the progeny of the original irradiated cells. In the radiation-leukemogenesis, there is no significant difference between controls and CBA/H mouses of PPI (preconception patent irradiation), but the offsprings of the PPI recipients show a different character (shorter latent period and higher incidence) after an extra γ-radiation. The radiation-induced genomic instability may get the genome on the verge of mutation and lead to carcinogens following mutation of some critical genes. The genomic instability, as the early event of initiation of carcinomas, may be play a specific or unique role

  17. Was Muller's 1946 Nobel Prize research for radiation-induced gene mutations peer-reviewed?

    Science.gov (United States)

    Calabrese, Edward J

    2018-06-06

    This historical analysis indicates that it is highly unlikely that the Nobel Prize winning research of Hermann J. Muller was peer-reviewed. The published paper of Muller lacked a research methods section, cited no references, and failed to acknowledge and discuss the work of Gager and Blakeslee (PNAS 13:75-79, 1927) that claimed to have induced gene mutation via ionizing radiation six months prior to Muller's non-data Science paper (Muller, Science 66(1699):84-87, 1927a). Despite being well acclimated into the scientific world of peer-review, Muller choose to avoid the peer-review process on his most significant publication. It appears that Muller's actions were strongly influenced by his desire to claim primacy for the discovery of gene mutation. The actions of Muller have important ethical lessons and implications today, when self-interest trumps one's obligations to society and the scientific culture that supports the quest for new knowledge and discovery.

  18. Induced mutation in tropical fruit trees

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-05-15

    This publication is based on an FAO/IAEA coordinated research project (CRP) and provides insight into the application of induced mutation and in vitro techniques for the improvement of well known fruit trees such as citrus, mango, avocado and papaya, as well as more exotic fruit trees such as litchi, annona, jujube, carambola, pitanga and jaboticaba. The latter are of particular importance due to their adaptation to harsh environments and their high potential as basic food and micronutrient providers for populations in poorer and more remote regions. The findings of the CRP show that application of radiation induced mutation techniques in tropical and subtropical fruit trees can contribute to improving nutritional balance food security, and to enhancing the economic status of growers.

  19. Induced mutation in tropical fruit trees

    International Nuclear Information System (INIS)

    2009-05-01

    This publication is based on an FAO/IAEA coordinated research project (CRP) and provides insight into the application of induced mutation and in vitro techniques for the improvement of well known fruit trees such as citrus, mango, avocado and papaya, as well as more exotic fruit trees such as litchi, annona, jujube, carambola, pitanga and jaboticaba. The latter are of particular importance due to their adaptation to harsh environments and their high potential as basic food and micronutrient providers for populations in poorer and more remote regions. The findings of the CRP show that application of radiation induced mutation techniques in tropical and subtropical fruit trees can contribute to improving nutritional balance food security, and to enhancing the economic status of growers

  20. Estimating spontaneous mutation rates at enzyme loci in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Mukai, Terumi; Yamazaki, Tsuneyuki; Harada, Ko; Kusakabe, Shin-ichi

    1990-04-01

    Spontaneous mutations were accumulated for 1,620,826 allele-generations on chromosomes that originated from six stem second chromosomes of Drosophila melanogaster. Only null-electromorph mutations were detected. Band-electromorph mutations were not found. The average rate of null-electromorph mutations was 2.71 x 10 -5 per locus per generation. The 95% confidence interval (μ n ) was 1.97 x 10 -5 n -5 per locus per generation. The upper 95% confidence limit of the band-electromorph mutation rate (μ B ) was 2.28 x 10 -6 per locus per generation. It appeared that null mutations were induced by movable genetic elements and that the mutation rates were different from chromosome to chromosome. (author)

  1. Mutation effect of streptomyces kitasatoensis after exposure to heavy ions radiation

    International Nuclear Information System (INIS)

    Liu Jing; Chen Jihong; Wang Shuyang; Li Wenjian

    2011-01-01

    To define the optimum dose of heavy ion beams for selecting high productive strains, we should study mortality and mutation effects of Streptomyces kitasatoensis irradiated by heavy ion beams in different doses. In this research, spores of Streptomyces kitasatoensis were irradiated by heavy ion beams with different doses. And survival rate, mortality rate, positive mutation and negative mutation were analyzed statistically. The results showed that high mortality rate appeared from 5 Gy and then the mortality rate curve became gently. Compared the positive and negative mutations in different doses, highest positive mutation was obtained in 40 Gy, while the negative mutation was lower in this dose, and the survival rate was 0.92%. So we defined that optimum dose of heavy ions radiation for Streptomyces kitasatoensis selection was 40 Gy in this experiment. (authors)

  2. Analysis of radiation-induced genome alterations in Vigna unguiculata

    Directory of Open Access Journals (Sweden)

    van der Vyver C

    2011-09-01

    Full Text Available Christell van der Vyver1, B Juan Vorster2, Karl J Kunert3, Christopher A Cullis41Institute for Plant Biotechnology, Department of Genetics, University of Stellenbosch, Stellenbosch, South Africa; 2Department of Plant Production and Soil Science, and 3Department of Plant Science, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa; 4Case Western Reserve University, Department of Biology, Cleveland, OH, USAAbstract: Seeds from an inbred Vigna unguiculata (cowpea cultivar were gamma-irradiated with a dose of 180 Gy in order to identify and characterize possible mutations. Three techniques, ie, random amplified polymorphic DNA, microsatellites, and representational difference analysis, were used to characterize possible DNA variation among the mutants and nonirradiated control plants both immediately after irradiation and in subsequent generations. A large portion of putative radiation-induced genome changes had significant similarities to chloroplast sequences. The frequency of mutation at three of these isolated polymorphic regions with chloroplast similarity was further determined by polymerase chain reaction screening using a large number of individual parental, M1, and M2 plants. Analysis of these sequences indicated that the rate at which various regions of the genome is mutated in irradiation experiments differs significantly and also that mutations have variable “repair” rates. Furthermore, regions of the nuclear DNA derived from the chloroplast genome are highly susceptible to modification by radiation treatment. Overall, data have provided detailed information on the effects of gamma irradiation on the cowpea genome and about the ability of the plant to repair these genome changes in subsequent plant generations.Keywords: mutation breeding, gamma radiation, genetic mutations, cowpea, representational difference analysis

  3. Alkylating agent (MNU)-induced mutation in space environment

    Science.gov (United States)

    Ohnishi, T.; Takahashi, A.; Ohnishi, K.; Takahashi, S.; Masukawa, M.; Sekikawa, K.; Amano, T.; Nakano, T.; Nagaoka, S.

    2001-01-01

    In recent years, some contradictory data about the effects of microgravity on radiation-induced biological responses in space experiments have been reported. We prepared a damaged template DNA produced with an alkylating agent (N-methyl-N-nitroso urea; MNU) to measure incorrect base-incorporation during DNA replication in microgravity. We examined whether mutation frequency is affected by microgravity during DNA replication for a DNA template damaged by an alkylating agent. Using an in vitro enzymatic reaction system, DNA synthesis by Taq polymerase or polymerase III was done during a US space shuttle mission (Discovery, STS-91). After the flight, DNA replication and mutation frequencies were measured. We found that there was almost no effect of microgravity on DNA replication and mutation frequency. It is suggested that microgravity might not affect at the stage of substrate incorporation in induced-mutation frequency.

  4. Sequential mutations in Notch1, Fbxw7, and Tp53 in radiation-induced mouse thymic lymphomas.

    Science.gov (United States)

    Jen, Kuang-Yu; Song, Ihn Young; Banta, Karl Luke; Wu, Di; Mao, Jian-Hua; Balmain, Allan

    2012-01-19

    T-cell acute lymphoblastic lymphomas commonly demonstrate activating Notch1 mutations as well as mutations or deletions in Fbxw7. However, because Fbxw7 targets Notch1 for degradation, genetic alterations in these genes are expected to be mutually exclusive events in lymphomagenesis. Previously, by using a radiation-induced Tp53-deficient mouse model for T-cell acute lymphoblastic lymphoma, we reported that loss of heterozygosity at the Fbxw7 locus occurs frequently in a Tp53-dependent manner. In the current study, we show that these thymic lymphomas also commonly exhibit activating Notch1 mutations in the proline-glutamic acid-serine-threonine (PEST) domain. Moreover, concurrent activating Notch1 PEST domain mutations and single-copy deletions at the Fbxw7 locus occur with high frequency in the same individual tumors, indicating that these changes are not mutually exclusive events. We further demonstrate that although Notch1 PEST domain mutations are independent of Tp53 status, they are completely abolished in mice with germline Fbxw7 haploinsufficiency. Therefore, Notch1 PEST domain mutations only occur when Fbxw7 expression levels are intact. These data suggest a temporal sequence of mutational events involving these important cancer-related genes, with Notch1 PEST domain mutations occurring first, followed by Fbxw7 deletion, and eventually by complete loss of Tp53.

  5. Radiation-induced attenuation in polarization maintaining fibers: low dose rate response, stress, and materials effects

    International Nuclear Information System (INIS)

    Gingerich, M.E.; Friebele, E.J.; Hickey, S.J.; Brambani, L.A.; Onstott, J.R.

    1989-01-01

    The loss induced in polarization-maintaining (PM) fibers by low dose rate <0.01 Gy/h, where 1 Gy = 100 rads(Si) radiation exposure has been found to vary from <0.4 to ∼6 dB/km-10 Gy, depending on the wavelength of measurement and the fiber. Correlations have been established between low dose rate response and the ''permanent'' induced loss determined by fitting the recovery of the induced loss following high dose rate exposure to nth-order kinetics. Using this technique, both 0.85- and 1.3-μm PM fibers have been found which show virtually no permanent incremental loss and would therefore appear to be resistant to low dose rate radiation environments. The asymmetric stress inherent in PM fibers has been shown to reduce the permanent induced loss, while the recovery of the radiation-induced attenuation was found to be enhanced in fibers with Ge-F-doped silica clads

  6. Radiation-induced malignant tumours: a specific cytogenetic profile?

    International Nuclear Information System (INIS)

    Chauveinc, L.; Gaboriaux, G.; Dutrillaux, A. M.; Dutrillaux, B.; Chauveinc, L.; Ricoul, M.; Sabatier, L.; Dutrillaux, B.

    1997-01-01

    To date, there is no criterion enabling to determine the spontaneous or radio-induced origin of malignant tumour occurring in a previously irradiated patient. Biological studies are rare. The cytogenetic data which could be found in the literature for eleven radio-induced tumours suggest that aneuploidies and polyclonality are frequent events. We studied, by R-Banding cytogenetic technique, five patients with short-term cultures (3 cases), short and long-term cultures (1 case) and xeno-grafting on nude pattern a high rate of balanced translocations, numerous random break points and a polyclonal evolution (10 clones). All other tumours, including the xeno-grafting sarcoma, had a monoclonal profile with complex karyotypes, hypo-diploid formulas and many deletions. These results show that the mechanism of radiation-induced tumours frequently involves chromosomes losses and deletions. The most likely explanation is that these alterations unmask radiation induced recessive mutations of tumour suppressor genes. (authors)

  7. Quantitative evaluation of DNA damage and mutation rate by atmospheric and room-temperature plasma (ARTP) and conventional mutagenesis.

    Science.gov (United States)

    Zhang, Xue; Zhang, Chong; Zhou, Qian-Qian; Zhang, Xiao-Fei; Wang, Li-Yan; Chang, Hai-Bo; Li, He-Ping; Oda, Yoshimitsu; Xing, Xin-Hui

    2015-07-01

    DNA damage is the dominant source of mutation, which is the driving force of evolution. Therefore, it is important to quantitatively analyze the DNA damage caused by different mutagenesis methods, the subsequent mutation rates, and their relationship. Atmospheric and room temperature plasma (ARTP) mutagenesis has been used for the mutation breeding of more than 40 microorganisms. However, ARTP mutagenesis has not been quantitatively compared with conventional mutation methods. In this study, the umu test using a flow-cytometric analysis was developed to quantify the DNA damage in individual viable cells using Salmonella typhimurium NM2009 as the model strain and to determine the mutation rate. The newly developed method was used to evaluate four different mutagenesis systems: a new ARTP tool, ultraviolet radiation, 4-nitroquinoline-1-oxide (4-NQO), and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) mutagenesis. The mutation rate was proportional to the corresponding SOS response induced by DNA damage. ARTP caused greater DNA damage to individual living cells than the other conventional mutagenesis methods, and the mutation rate was also higher. By quantitatively comparing the DNA damage and consequent mutation rate after different types of mutagenesis, we have shown that ARTP is a potentially powerful mutagenesis tool with which to improve the characteristics of microbial cell factories.

  8. Molecular alterations underlying the spontaneous and γ-ray-induced point mutations at the white locus of Drosophila Melanogaster

    International Nuclear Information System (INIS)

    Aleksandrova, M.V.; Lapidus, I.L.; Aleksandrov, I.D.; Karpovskij, A.L.

    1996-01-01

    The white locus in D.Melanogaster was selected as a target gene for the study of the mutational spectra of spontaneously arising and radiation-induced gene mutations in a whole organism. Analysis of 6 spontaneous and 73 γ-ray-induced white mutations by a combination of cytological, genetic and molecular techniques revealed that on the chromosomal and genetic levels all spontaneous mutations showed themselves to be point mutants. The share of such mutants among all heritable radiation-induced gene mutations is about 40%, whereas the rest ones are due to exchange breaks (8%) as well as multilocus, single-locus or partial-locus (intragenic) deletions (52%). The DNAs from 4 spontaneous and 17 γ-ray-induced point mutants were analysed by Southern blot-hybridization. The three spontaneous and 7 radiation mutants showed an altered DNA sequence at the left (distal) half of the white gene due to insertion or DNA rearrangement. The rest (58%) of the radiation-induced point mutations did not indicate any alternations in this part of the gene as detected by this technique and probes employed. 15 refs., 3 figs., 1 tab

  9. Development of breeding materials in rice by use of induced mutation

    International Nuclear Information System (INIS)

    Amano, Etsuo

    1988-01-01

    On this 25th Gamma Field Symposium, it may be worth while to review the world situation of mutation breeding, the possibility expected to mutation methods suggested by the ever progressing genetics in rice plant, and some of the activities in the Institute of Radiation Breeding. By the help of a small computer, the key word search analysis of 'Mutation Breeding Newsletter and Mutation Breeding Review' was tried, and the results are included in this review to see the present status. The studies on artificially induced mutation suggested that the possibility of dominant mutation is less. It might be probable that the inactivation of genes is the mechanism of mutation. Still the possibility of using mutation breeding techniques for many genetic characters was suggested. After the experience for 25 years, detailed genetical and fine structure analyses became important. The studies on the expression of mutant phenotypes including molecular genetics will help to develop radiation breeding into an effective means to enrich the genetic resources for breeding. The situation in the world, the genes reported in rice, the possibility to induce useful mutants against environmental stress, the mutation in the protein content in grains, the mutants of storage carbohydrate, the possibility to widen gene resources and so on are reported. (Kako, I.)

  10. Retrospective genetic study of germinative mutations in Str loci of individuals potentially exposed to ionizing radiation;Estudo genetico retrospectivo de mutacoes germinativas em Loci Str de individuos potencialmente expostos a radiacao ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Emilia Oliveira Alves

    2010-07-01

    The Brazilian radiological accident that occurred in 1987, in Goiania, it was a terrible radiation episode. As a consequence, hundreds of people were contaminated due to the Cesium-137 radiation. Recently, many studies had shown that genome instabilities, such as, mutations, chromosomal aberrations, micronuclei formation and micro satellite instability and a delay on cellular death are usually reported on mammal cells exposed to ionizing radiation, being considered as a manly risk to humans. Mutations can be spontaneous, and the occurrence is dependent on the organism, or, induced, being associated to mutagenic exposition. Ionizing radiations are an example of physical and mutagenic agents that could harm the cell repair and could cause the development of many types of cancer. The evaluation of the biological effects of the ionizing radiation, in somatic and germ line cells, with a consequent determination of the radio-induced mutations, it is extremely important to estimate the genetic risks, manly in population exposed to radiation. The analyses of repetitive DNA sequences have been demonstrated that such sequences are prone to high rates of spontaneous mutations. The minisatellites and microsatellites have been used to demonstrate the induction of germ line mutation rates on mouse, humans, among others organisms. The aim of the present study was to analyze the frequency of microsatellite alterations to determine the mutation rates occurred in germ cells of the parents exposed to the ionizing radiation of the Cesium-137. The studied group was constitute of 10 families of individuals accidentally exposed to Cesium-137 and by the control group constituted by 645 healthy individuals who carried out paternity tests on 2009. We found only one mutation of paternal origin in the D8S1179 locus on the exposed group, being the mutation rate of 0.002. In the control group, we found 01 mutation on D16S539 loei and on D3S1358; 02 mutations on Penta E loeus; 04 mutations on D

  11. Gamma Radiation-Induced Mutations in Soybeans

    International Nuclear Information System (INIS)

    Smutkupt, S.

    1998-01-01

    The main objective of soybean radiation experiments was to create genetic variability in soybeans of various cultivars, mutants and mutation-derived lines with the aim of producing superior breeding lines with resistance to soybean rust (Phakopsora pachyhrizi Syd.) It took altogether 12 generations over six years after gamma irradiation if soybean seeds to produce the best resistant line (81-1-038) which a variety could be developed from it. This Line 81-1-038 showed a very good specific resistance to soybean rust, Thai race 2 and moderately resistance to Thai race 1. In the rainy season of 1985, Line 81-1-038 out yielded S.J.4 (a mother line) by 868 kg/ha in a yield trail at Suwan Farm, Pak Chong, Nakorn Rajchasima. This soybean rust mutant was later named D oi Kham

  12. Use of γ-ray-induced mutations in the genome era in rice

    International Nuclear Information System (INIS)

    Kusaba, Makoto

    2007-01-01

    Ionizing radiation has been used for inducing mutations and improving crops since the discovery by STADLER (1928) that X-rays could induce mutations in barley. At the end of 2004, the whole genome sequence of rice was determined (INTERNATIONAL RICE GENOME SEQUENCING PROJECT, 2005). What can γ-ray-induced mutations contribute now that this has been achieved? One answer could be the elucidation of the functions of the numerous genes revealed by the complete sequence of the rice genome. This includes identification of mutants through reverse genetics and the isolation of genes containing mutations through forward genetics using molecular markers and sequence information. Another answer could be mutation breeding using reverse genetics. But first we must know what kind of DNA lesions are caused by γ-rays. In this article, I describe the production of DNA lesions, and then discuss how γ-ray-induced mutations can contribute to the elucidation of gene function and to mutation breeding. (author)

  13. Advances and prospects for induced mutation breeding in Helongjiang Province

    International Nuclear Information System (INIS)

    Sun Guangzu

    1995-12-01

    Induced mutation breeding employed on soybean, spring wheat, maize, millet, fiber flax, chinese cabbage, kidney been and garlic in Heilongjiang province. Thirty-six new varieties had introduced and released from 1980 to 1994, made up 20.6% of total released varieties for the same period, accumulated cultivated area of 3.746 million hm 2 , and increased the income of formers to US dollar 168 million; 72 mutants having specific and utilizing values and traits have also been bred in the province. Basic research such as radiation breeding in combination with distant hybridization, biotechnology, and application new induced factors, improving selection methods, have been achieved; 91 articles have been published. These researches play an important role for increasing induced mutation breeding. Three items of suggestion to develop induced mutation breeding are made. (1 tab.)

  14. The split-sting trait in Apis mellifera induced by cobalt 60 gamma radiation

    International Nuclear Information System (INIS)

    Silva, Vera Lucia Maciel

    1993-01-01

    The Split-Sting (SS) trait in honey bees, induced by gamma radiation, was discovered by Soares (1975). Bees with this trait are unable to sting, because the parts that compose the sting are separated. Many studies have been done in order to understand this new mutation. We studied the effect of gamma radiation on induction of the SS trait in feral bee strains. The doses were applied to the phase of larvae of queens with 5 days old. The following results were obtained: all doses of radiation induced the SS trait. There was an increase in the percentage of queens with SS with an increase in radiation dose; the SS trait induced by radiation is probably phenocopy; SS bees were observed in nature; increase of the rate mortality and malformation with an increase in radiation dose. (author)

  15. Epigenetic mechanism of radiation carcinogenesis

    International Nuclear Information System (INIS)

    Niwa, Ohtsura

    1995-01-01

    Carcinogenic action of radiations has long been thought to be due to its mutagenic activity. Since DNA damage is induced and distributes in a stochastic fashion, radiation induction of cancers was also assumed to follow a stochastic kinetics. However, recent progress in radiation research has revealed that some features of radiation carcinogenesis are not explainable by the simple action of radiation as a DNA damaging and mutagenic agent. Firstly, frequencies of radiation-induced transformation in vitro and radiation-induced mammary cancers in rats are too high to be accounted for by the frequency of radiation-induced mutation. Secondly, trans-generation carcinogenesis among F1 mice born to irradiated parents occurs also much more frequently than to be predicted by the frequency of radiation induced germline mutation. Thirdly, multistage carcinogenesis theory predicts that carcinogens give hits to the target cells so as to shorten the latency of cancers. However, latencies of radiation induced solid cancers among atomic bomb survivors are similar to those of the control population. Fourthly, although radiation elevates the frequency of cancers, the induced cancers seem to share the same spectrum of cancer types as in the unirradiated control populations. This suggests that radiation induces cancer by enhancement of the spontaneous carcinogenesis process. These data suggest that the first step of radiation carcinogenesis may not be the direct induction of mutation. Radiation may induce genetic instability which increases the spontaneous mutation rate in the cells to produce carcinogenic mutations. Growth stimulatory effect of radiation may also contribute to the process. Thus, epigenetic, but not genetic effect of radiation might better contribute in the process of carcinogenesis. (author)

  16. Death and population dynamics affect mutation rate estimates and evolvability under stress in bacteria.

    Science.gov (United States)

    Frenoy, Antoine; Bonhoeffer, Sebastian

    2018-05-01

    The stress-induced mutagenesis hypothesis postulates that in response to stress, bacteria increase their genome-wide mutation rate, in turn increasing the chances that a descendant is able to better withstand the stress. This has implications for antibiotic treatment: exposure to subinhibitory doses of antibiotics has been reported to increase bacterial mutation rates and thus probably the rate at which resistance mutations appear and lead to treatment failure. More generally, the hypothesis posits that stress increases evolvability (the ability of a population to generate adaptive genetic diversity) and thus accelerates evolution. Measuring mutation rates under stress, however, is problematic, because existing methods assume there is no death. Yet subinhibitory stress levels may induce a substantial death rate. Death events need to be compensated by extra replication to reach a given population size, thus providing more opportunities to acquire mutations. We show that ignoring death leads to a systematic overestimation of mutation rates under stress. We developed a system based on plasmid segregation that allows us to measure death and division rates simultaneously in bacterial populations. Using this system, we found that a substantial death rate occurs at the tested subinhibitory concentrations previously reported to increase mutation rate. Taking this death rate into account lowers and sometimes removes the signal for stress-induced mutagenesis. Moreover, even when antibiotics increase mutation rate, we show that subinhibitory treatments do not increase genetic diversity and evolvability, again because of effects of the antibiotics on population dynamics. We conclude that antibiotic-induced mutagenesis is overestimated because of death and that understanding evolvability under stress requires accounting for the effects of stress on population dynamics as much as on mutation rate. Our goal here is dual: we show that population dynamics and, in particular, the

  17. The nature of radiation-induced mutations at the white locus of Drosophila melanogaster

    International Nuclear Information System (INIS)

    Pastink, A.; Schalet, A.P.; Vreeken, C.; Eeken, J.C.J.; Paradi, E.

    1987-01-01

    X-ray- and neutron-induced mutations at the white locus of Drosophila melanogaster were used to study the nature of radiation-induced genetic damage. Genetic analysis showed the presence of multi-locus deficiencies in 15 out of 31 X-ray mutants and in 26 out of 35 mutants induced by neutrons. The DNA from 11 X-ray and 4 neutron mutants, which were not multi-locus deficiencies, was analyzed by Southern blot-hybridization. Deletions were observed in 2 X-ray and 1 neutron mutant. In combination with cytogenetic techniques, chromosomal rearrangements affecting the white locus (translocations, inversions, etc.) were identified in 3 X-ray and in 2 neutron mutants. A hot-spot for translocation breakpoints was identified in the left arm of the third chromosome. 5 X-ray mutants, which apparently did not contain large deletions, were subjected to further analysis by the nuclease S1 protection method, after cloning of the white gene. In 4 mutants a small deletion could indeed be detected in this way. Thus it seems that by far the main part of X-ray- and neutron-induced white mutants have arisen through large changes in the white gene, especially deletions. (Auth.)

  18. Radiation-induced mutagenicity and lethality in tryptophan-requiring auxotrophs of escherichia coli

    International Nuclear Information System (INIS)

    Xu Rong; Qian Hongwei; Yao Fenying; Gu Shuzhu; Xu Jiaxin; Bi Hekan; Liu Yuying

    1989-01-01

    Mutation and killing caused by X-ray radiation and 60 Co γ-ray radiation were studied in three different tryptophan-requiring auxotrophs (WP2, Wp2A, Cm 891) of Escherichia coli. These testers are sensitive to base pair substitution mutagens. Cm891 carries a R-factor and is more sensitive than WP2 and WP2A to radiation-induced mutation and lethality. The results of the study show that (1) ionizing radiation was mutagenic to E. coli, (2) the order of mutagenic sensitivity among three strains to ionizing radiation was Cm891 > WP2A > WP2, (3) the dose rate of γ-ray influences mutagenicity and lethalty of E. coli strain, (4) the toxicity and mutagenicity of γ-ray were similar to X-ray when Cm891 was tested, however, γ-ray was more toxic and mutagenic than X-ray to WP2A ang WP2

  19. Carcinogenesis induced by low-dose radiation

    Directory of Open Access Journals (Sweden)

    Piotrowski Igor

    2017-11-01

    Full Text Available Although the effects of high dose radiation on human cells and tissues are relatively well defined, there is no consensus regarding the effects of low and very low radiation doses on the organism. Ionizing radiation has been shown to induce gene mutations and chromosome aberrations which are known to be involved in the process of carcinogenesis. The induction of secondary cancers is a challenging long-term side effect in oncologic patients treated with radiation. Medical sources of radiation like intensity modulated radiotherapy used in cancer treatment and computed tomography used in diagnostics, deliver very low doses of radiation to large volumes of healthy tissue, which might contribute to increased cancer rates in long surviving patients and in the general population. Research shows that because of the phenomena characteristic for low dose radiation the risk of cancer induction from exposure of healthy tissues to low dose radiation can be greater than the risk calculated from linear no-threshold model. Epidemiological data collected from radiation workers and atomic bomb survivors confirms that exposure to low dose radiation can contribute to increased cancer risk and also that the risk might correlate with the age at exposure.

  20. Effects of diurnal temperature difference and gamma radiation on the frequency of somatic cell mutations in the stamen hairs

    International Nuclear Information System (INIS)

    Kim, Jin Kyu; Kim, Won Rok; Kim, Jae Sung; Shin, Hae Shick; Lee, Jeong Joo

    1998-01-01

    This study deals with the effects of diurnal temperature difference (DTD) on somatic cell mutation frequencies in Tradescantia stamen hairs irradiated with radiation. Potted plants of Tradescantia 4430 were irradiated with 0.3, 0.5, 1.0 and 2.0 Gy of gamma radiation. The irradiated plants were maintained under two different experimental conditions; at constant temperature of 20 degree C (DTD0) and at 28 degree C for 14-h day and 8 degree C for 10-h night (DTD20). The somatic cell mutation rate in 0.5 Gy irradiated group showed a big increase on the 6th day and reached a maximum value on the 10th day after irradiation while the rate in the experimental group under the condition of DTD20 started to increase on the 8th day and got to a maximal value on the 14th day postirradiation. In both of the two experiments, the dose-response relationships were clearly linear. The slope of the DTD20 dose-response curve was much steeper than that of the DTD0 one. In conclusion, a great DTD, as one of environmental stresses, enhanced the effectiveness of radiation in the induction of somatic cell mutations and caused a shift of the peak interval of radiation-induced mutations in Tradescantia stamen hairs

  1. WNT activation by lithium abrogates TP53 mutation associated radiation resistance in medulloblastoma.

    Science.gov (United States)

    Zhukova, Nataliya; Ramaswamy, Vijay; Remke, Marc; Martin, Dianna C; Castelo-Branco, Pedro; Zhang, Cindy H; Fraser, Michael; Tse, Ken; Poon, Raymond; Shih, David J H; Baskin, Berivan; Ray, Peter N; Bouffet, Eric; Dirks, Peter; von Bueren, Andre O; Pfaff, Elke; Korshunov, Andrey; Jones, David T W; Northcott, Paul A; Kool, Marcel; Pugh, Trevor J; Pomeroy, Scott L; Cho, Yoon-Jae; Pietsch, Torsten; Gessi, Marco; Rutkowski, Stefan; Bognár, Laszlo; Cho, Byung-Kyu; Eberhart, Charles G; Conter, Cecile Faure; Fouladi, Maryam; French, Pim J; Grajkowska, Wieslawa A; Gupta, Nalin; Hauser, Peter; Jabado, Nada; Vasiljevic, Alexandre; Jung, Shin; Kim, Seung-Ki; Klekner, Almos; Kumabe, Toshihiro; Lach, Boleslaw; Leonard, Jeffrey R; Liau, Linda M; Massimi, Luca; Pollack, Ian F; Ra, Young Shin; Rubin, Joshua B; Van Meir, Erwin G; Wang, Kyu-Chang; Weiss, William A; Zitterbart, Karel; Bristow, Robert G; Alman, Benjamin; Hawkins, Cynthia E; Malkin, David; Clifford, Steven C; Pfister, Stefan M; Taylor, Michael D; Tabori, Uri

    2014-12-24

    TP53 mutations confer subgroup specific poor survival for children with medulloblastoma. We hypothesized that WNT activation which is associated with improved survival for such children abrogates TP53 related radioresistance and can be used to sensitize TP53 mutant tumors for radiation. We examined the subgroup-specific role of TP53 mutations in a cohort of 314 patients treated with radiation. TP53 wild-type or mutant human medulloblastoma cell-lines and normal neural stem cells were used to test radioresistance of TP53 mutations and the radiosensitizing effect of WNT activation on tumors and the developing brain. Children with WNT/TP53 mutant medulloblastoma had higher 5-year survival than those with SHH/TP53 mutant tumours (100% and 36.6%±8.7%, respectively (p<0.001)). Introduction of TP53 mutation into medulloblastoma cells induced radioresistance (survival fractions at 2Gy (SF2) of 89%±2% vs. 57.4%±1.8% (p<0.01)). In contrast, β-catenin mutation sensitized TP53 mutant cells to radiation (p<0.05). Lithium, an activator of the WNT pathway, sensitized TP53 mutant medulloblastoma to radiation (SF2 of 43.5%±1.5% in lithium treated cells vs. 56.6±3% (p<0.01)) accompanied by increased number of γH2AX foci. Normal neural stem cells were protected from lithium induced radiation damage (SF2 of 33%±8% for lithium treated cells vs. 27%±3% for untreated controls (p=0.05). Poor survival of patients with TP53 mutant medulloblastoma may be related to radiation resistance. Since constitutive activation of the WNT pathway by lithium sensitizes TP53 mutant medulloblastoma cells and protect normal neural stem cells from radiation, this oral drug may represent an attractive novel therapy for high-risk medulloblastomas.

  2. Further evidence for elevated human minisatellite mutation rate in Belarus eight years after the Chernobyl accident

    International Nuclear Information System (INIS)

    Dubrova, Yuri E.; Buard, Jerome; Jeffreys, Alec J.; Nesterov, Valeri N.; Krouchinsky, Nicolay G.; Ostapenko, Vladislav A.; Vergnaud, Gilles; Giraudeau, Fabienne

    1997-01-01

    Analysis of germline mutation rate at human minisatellites among children born in areas of the Mogilev district of Belarus heavily polluted after the Chernobyl accident has been extended, both by recruiting more families from the affected region and by using five additional minisatellite probes, including multi-locus probe 33.6 and four hypervariable single-locus probes. These additional data confirmed a twofold higher mutation rate in exposed families compared with non-irradiated families from the United Kingdom. An elevated rate was seen at all three independent sets of minisatellites (detected separately by multi-locus probes 33.15, 33.6 and six single-locus probes), indicating a generalised increase in minisatellite germline mutation rate in the Belarus families. Within the Belarus cohort, mutation rate was significantly greater in families with higher parental radiation dose estimated for chronic external and internal exposure to caesium-137, consistent with radiation induction of germline mutation. The spectra of mutation seen in the unexposed and exposed families were indistinguishable, suggesting that increased mutation observed over multiple loci arises indirectly by some mechanism that enhances spontaneous minisatellite mutation

  3. X-ray-induced mutations in Escherichia coli K-12 strains with altered DNA polymerase I activities

    International Nuclear Information System (INIS)

    Nagata, Yuki; Kawata, Masakado; Komura, Jun-ichiro; Ono, Tetsuya; Yamamoto, Kazuo

    2003-01-01

    Spectra of ionizing radiation mutagenesis were determined by sequencing X-ray-induced endogenous tonB gene mutations in Escherichia coli polA strains. We used two polA alleles, the polA1 mutation, defective for Klenow domain, and the polA107 mutation, defective for flap domain. We demonstrated that irradiation of 75 and 50 Gy X-rays could induce 3.8- and 2.6-fold more of tonB mutation in polA1 and polA107 strains, respectively, than spontaneous level. The radiation induced spectrum of 51 tonB mutations in polA1 and 51 in polA107 indicated that minus frameshift, A:T→T:A transversion and G:C→T:A transversion were the types of mutations increased. Previously, we have reported essentially the same X-ray-induced tonB mutation spectra in the wild-type strain. These results indicate that (1) X-rays can induce minus frameshift, A:T→T:A transversion and G:C→T:A transversion in E. coli and (2) presence or absence of polymerase I (PolI) of E. coli does not have any effects on the process of X-ray mutagenesis

  4. Perspectives in the paradigm of radiation-induced carcinogenesis

    International Nuclear Information System (INIS)

    Sugakhara, T.; Vatanabe, M.; Niva, O.; Nikajdo, O.

    1995-01-01

    Carcinogenesis is analysed as a multistage process consisting of initiation, promotion and progression. This model includes the mutation of oncogenes and the loss of hetrezygosity by tumor-suppressor genes. The threshold concept of radiation cancerogenesis is proposed, under which ionizing radiation can induce in somatic cell genetic effects a s result of DNA damage and epigenetic changes as well. The epigenetic changes (through DNA or cytoplasma) can be stabilized as mutations observed in many cancer cells and play a dominant role in radiation cancerogenesis induction. The ration of epigenetic and genetic effects largely depends on radiation doses

  5. Germline minisatellite mutations in workers occupationally exposed to radiation at the Sellafield nuclear facility

    International Nuclear Information System (INIS)

    Tawn, E Janet; Curwen, Gillian B; Rees, Gwen S; Jonas, Patricia

    2015-01-01

    Germline minisatellite mutation rates were investigated in male workers occupationally exposed to radiation at the Sellafield nuclear facility. DNA samples from 160 families with 255 offspring were analysed for mutations at eight hypervariable minisatellite loci (B6.7, CEB1, CEB15, CEB25, CEB36, MS1, MS31, MS32) by Southern hybridisation. No significant difference was observed between the paternal mutation rate of 5.0% (37 mutations in 736 alleles) for control fathers with a mean preconceptional testicular dose of 9 mSv and that of 5.8% (66 in 1137 alleles) for exposed fathers with a mean preconceptional testicular dose of 194 mSv. Subgrouping the exposed fathers into two dose groups with means of 111 mSv and 274 mSv revealed paternal mutation rates of 6.0% (32 mutations in 536 alleles) and 5.7% (34 mutations in 601 alleles), respectively, neither of which was significantly different in comparisons with the rate for the control fathers. Maternal mutation rates of 1.6% (12 mutations in 742 alleles) for the partners of control fathers and 1.7% (19 mutations in 1133 alleles) for partners of exposed fathers were not significantly different. This study provides evidence that paternal preconceptional occupational radiation exposure does not increase the germline minisatellite mutation rate and therefore refutes suggestions that such exposure could result in a destabilisation of the germline that can be passed on to future generations. (paper)

  6. Radiation-induced genomic instability and bystander effects: related inflammatory-type responses to radiation-induced stress and injury? A review.

    Science.gov (United States)

    Lorimore, S A; Wright, E G

    2003-01-01

    To review studies of radiation responses in the haemopoietic system in the context of radiation-induced genomic instability, bystander effects and inflammatory-type processes. There is considerable evidence that cells that themselves are not exposed to ionizing radiation but are the progeny of cells irradiated many cell divisions previously may express a high frequency of gene mutations, chromosomal aberrations and cell death. These effects are collectively known as radiation-induced genomic instability. A second untargeted effect results in non-irradiated cells exhibiting responses typically associated with direct radiation exposure but occurs as a consequence of contact with irradiated cells or by receiving soluble signals from irradiated cells. These effects are collectively known as radiation-induced bystander effects. Reported effects include increases or decreases in damage-inducible and stress-related proteins; increases or decreases in reactive oxygen species, cell death or cell proliferation, and induction of mutations and chromosome aberrations. This array of responses is reminiscent of effects mediated by cytokines and other similar regulatory factors that may involve, but do not necessarily require, gap junction-mediated transfer, have multiple inducers and a variety of context-dependent consequences in different cell systems. That chromosomal instability in haemopoietic cells can be induced by an indirect bystander-type mechanism both in vitro and in vivo provides a potential link between these two untargeted effects and there are radiation responses in vivo consistent with the microenvironment contributing secondary cell damage as a consequence of an inflammatory-type response to radiation-induced injury. Intercellular signalling, production of cytokines and free radicals are features of inflammatory responses that have the potential for both bystander-mediated and persisting damage as well as for conferring a predisposition to malignancy. The

  7. Radiation-induced mutagenicity and lethality in Salmonella typhimurium

    International Nuclear Information System (INIS)

    Isildar, M.; Bakale, G.

    1983-01-01

    The mutagenic and lethal effects of ionizing radiation on histidine-deficient auxotrophs of Salmonella typhimurium were studied to improve the understanding of radiation damage to DNA. The auxotrophs were divided into two groups - one which is sensitive to base-pair substitutions and another sensitive to frameshifts. These groups were composed of parent-daughter pairs in which the chemical mutagenicity enhancing plasmid, pKM101, is absent in the parent strain and present in the daughter. Co-60 #betta#-radiation and 250 kV x-rays were used to irradiate the bacteria. Irradiation of the frameshift - sensitive strains which carry the pKm101 plasmid doubled the absolute number of induced revertants whereas irradiation of the base-pair substitution sensitive strain which also carries the pKm101 plasmid produced nearly no change in the number of induced revertants. A nearly negligible effect on the mutation rate was observed for all parent strains

  8. physical, chemical, technological and biological properties of some mutant oil seeds induced by gamma radiation

    International Nuclear Information System (INIS)

    Ali, H.G.M.

    2003-01-01

    The present study has been undertaken to evaluated sesame, sunflower and safflower seeds induced by gamma rays, as plant breeding unit, plant research department, radioisotope application division, nuclear research center, atomic energy authority Inshas. the obtained results indicate the following : chemical composition of mutant seeds: the radiation mutation caused a significant increase in both oil and ash content total carbohydrates showed a significant decreased in sesame seeds. radiation mutation induced significant increase in oil and protein content of sunflower and safflower seeds. while the total carbohydrate showed a significant decrease. physiochemical properties of oils extracted mutant seeds: the radiation mutation had no real effect on the refractive index and A.V of oils extracted from control and mutant sesame, sunflower and safflower seeds. while it caused a slight increase in red color and P.V. of sesame oil, the thiobarbituric acid (TBA) value of mutant sesame oil was not alter upon radiation mutation, but it induced a slight decrease in TBA of mutant sunflower and safflower oils. the unsaponifiable matter percentage of oils extracted from mutant sesame, sunflower and safflower seeds were slightly increased by radiation mutation .radiation mutation of seeds had no real effect on the total SFA and USFA of sesame oil. however, radiation mutation induced a remarkable changes in fatty acid profiles of sunflower and safflower oil as total SFA decreased, while USFA increased. Uric acid was only detected in oil extracted from mutant sunflower seeds

  9. The effect of spermine on spontaneous and UV-induced mutations in Schizosaccharomyces pombe

    International Nuclear Information System (INIS)

    Prendergast, J.A.; Kamra, O.P.; Nasim, A.

    1984-01-01

    The effect of different concentrations of spermine on spontaneous and UV-induced mutation in the adenine forward mutation system of Schizosaccharomyces pombe was investigated. The effect of spermine on spontaneous mutation was studied in 5 mutator strains (mut 1-4, mut 1-23, mut 2-9, mut 2-20 and mut 3-21) and on UV-induced mutation in a pigmented adenine-requiring strain and its radiation-sensitive derivative (rad 13). The effect of spermine exposure on mutation induction before and after UV irradiation was also investigated. Spermine increased spontaneous forward mutation in the mut 1-4 strain by 47% and enhanced UV-induced forward mutation 2-fold in the rad 13 and normal pigmented strains. No antimutagenic effect of spermine was seen in any of the strains tested. This is in marked contrast to the antimutagenic effect of spermine observed with bacteria. (Auth.)

  10. New mutations affecting induced mutagenesis in yeast.

    Science.gov (United States)

    Lawrence, C W; Krauss, B R; Christensen, R B

    1985-01-01

    Previously isolated mutations in baker's yeast, Saccharomyces cerevisiae, that impair induced mutagenesis were all identified with the aid of tests that either exclusively or predominantly detect base-pair substitutions. To avoid this bias, we have screened 11 366 potentially mutant clones for UV-induced reversion of the frameshift allele, his4-38, and have identified 10 mutants that give much reduced yields of revertants. Complementation and recombination tests show that 6 of these carry mutations at the previously known REV1, REV1 and REV3 loci, while the remaining 4 define 3 new genes, REV4 (2 mutations), REV5 and REV6. The rev4 mutations are readily suppressed in many genetic backgrounds and, like the rev5 mutation, impart only a limited deficiency for induced mutagenesis: it is likely, therefore that the REV4+ and REV5+ gene functions are only remotely concerned with this process. The rev6 mutants have a more general deficiency, however, as well as marked sensitivity to UV and an increased spontaneous mutation rate, properties that suggest the REV6 gene is directly involved in mutation induction. The REV5 gene is located about 1 cM proximal to CYC1 on chromosome X.

  11. Spontaneous mutation by mutagenic repair of spontaneous lesions in DNA

    International Nuclear Information System (INIS)

    Hastings, P.J.; Quah, S.-K.; Borstel, R.C. von

    1976-01-01

    It is stated that strains of yeast carrying mutations in many of the steps in pathways repairing radiation-induced damage to DNA have enhanced spontaneous mutation rates. Most strains isolated because they have enhanced spontaneous mutation carry mutations in DNA repair systems. This suggests that much spontaneous mutation arises by mutagenic repair of spontaneous lesions. (author)

  12. Radiation induced DNA damage and repair in mutagenesis

    International Nuclear Information System (INIS)

    Strniste, G.F.; Chen, D.J.; Okinaka, R.T.

    1987-01-01

    The central theme in cellular radiobiological research has been the mechanisms of radiation action and the physiological response of cells to this action. Considerable effort has been directed toward the characterization of radiation-induced DNA damage and the correlation of this damage to cellular genetic change that is expressed as mutation or initiating events leading to cellular transformation and ultimately carcinogenesis. In addition, there has been a significant advancement in their understanding of the role of DNA repair in the process of mutation leading to genetic change in cells. There is extensive literature concerning studies that address radiation action in both procaryotic and eucaryotic systems. This brief report will make no attempt to summarize this voluminous data but will focus on recent results from their laboratory of experiments in which they have examined, at both the cellular and molecular levels, the process of ionizing radiation-induced mutagenesis in cultured human cells

  13. [Comparative study of effect of infrared, submillimeter, and millimeter electromagnetic radiation on wing somatic mutations in Drosophila melanogaster induced by gamma-irradiation].

    Science.gov (United States)

    Fedorov, V I; Pogodin, A S; Dubatolova, T D; Varlamov, A V; Leont'ev, K V; Khamoian, A G

    2001-01-01

    It was shown that the number of spontaneous and gamma-radiation-induced somatic mutations in wing cells of fruit flies (third instar larvae) exposed to laser irradiation of submillimeter range (lambda = 81.5 microns) was significantly lower than in control. Laser irradiation did not affect the number of recombinations. Exposure to laser radiation in the infrared range and electromagnetic waves of the millimeter range (lambda = 3.8 mm) enhanced the effect of gamma-irradiation.

  14. Induced mutation in rice by in-vitro radiation

    International Nuclear Information System (INIS)

    Qi Xiufang; Zhao Chengzhang; Zhen Kangle

    1989-01-01

    The experiment indicated the adequate dose and growth stage for in-vitro radiation treatment. The results were: 1) Effect of 137 Cs-γ rays on redifferentiation and rate of green plantlets of somatic cells at different growth stage is different. The sequence of effect is callus>callus with green spots>callus with green shoot>mature embryo of dry seed. 2) The fertility of regenerated rice plants decreased with the radiation dose from 0 to 2.58 C/kg, and the rate of exserted stigma increased. 3) The occurence with early maturity increased up to 3.8%, among with about 0.5% of the plant lines matured 15 days earlier. 4) Tow male sterile lines with extruded stigmas were obtained, whose plant heights were reduced. Its frequency of occurance by in-vitro radiation is more than by coventional radiation and somatic cell culture

  15. Genomic instability and radiation

    Energy Technology Data Exchange (ETDEWEB)

    Little, John B [Harvard School of Public Health, Boston, MA 02115 (United States)

    2003-06-01

    Genomic instability is a hallmark of cancer cells, and is thought to be involved in the process of carcinogenesis. Indeed, a number of rare genetic disorders associated with a predisposition to cancer are characterised by genomic instability occurring in somatic cells. Of particular interest is the observation that transmissible instability can be induced in somatic cells from normal individuals by exposure to ionising radiation, leading to a persistent enhancement in the rate at which mutations and chromosomal aberrations arise in the progeny of the irradiated cells after many generations of replication. If such induced instability is involved in radiation carcinogenesis, it would imply that the initial carcinogenic event may not be a rare mutation occurring in a specific gene or set of genes. Rather, radiation may induce a process of instability in many cells in a population, enhancing the rate at which the multiple gene mutations necessary for the development of cancer may arise in a given cell lineage. Furthermore, radiation could act at any stage in the development of cancer by facilitating the accumulation of the remaining genetic events required to produce a fully malignant tumour. The experimental evidence for such induced instability is reviewed. (review)

  16. Genomic instability and radiation

    International Nuclear Information System (INIS)

    Little, John B

    2003-01-01

    Genomic instability is a hallmark of cancer cells, and is thought to be involved in the process of carcinogenesis. Indeed, a number of rare genetic disorders associated with a predisposition to cancer are characterised by genomic instability occurring in somatic cells. Of particular interest is the observation that transmissible instability can be induced in somatic cells from normal individuals by exposure to ionising radiation, leading to a persistent enhancement in the rate at which mutations and chromosomal aberrations arise in the progeny of the irradiated cells after many generations of replication. If such induced instability is involved in radiation carcinogenesis, it would imply that the initial carcinogenic event may not be a rare mutation occurring in a specific gene or set of genes. Rather, radiation may induce a process of instability in many cells in a population, enhancing the rate at which the multiple gene mutations necessary for the development of cancer may arise in a given cell lineage. Furthermore, radiation could act at any stage in the development of cancer by facilitating the accumulation of the remaining genetic events required to produce a fully malignant tumour. The experimental evidence for such induced instability is reviewed. (review)

  17. Elevated mutation rate during meiosis in Saccharomyces cerevisiae.

    Science.gov (United States)

    Rattray, Alison; Santoyo, Gustavo; Shafer, Brenda; Strathern, Jeffrey N

    2015-01-01

    Mutations accumulate during all stages of growth, but only germ line mutations contribute to evolution. While meiosis contributes to evolution by reassortment of parental alleles, we show here that the process itself is inherently mutagenic. We have previously shown that the DNA synthesis associated with repair of a double-strand break is about 1000-fold less accurate than S-phase synthesis. Since the process of meiosis involves many programmed DSBs, we reasoned that this repair might also be mutagenic. Indeed, in the early 1960's Magni and Von Borstel observed elevated reversion of recessive alleles during meiosis, and found that the revertants were more likely to be associated with a crossover than non-revertants, a process that they called "the meiotic effect." Here we use a forward mutation reporter (CAN1 HIS3) placed at either a meiotic recombination coldspot or hotspot near the MAT locus on Chromosome III. We find that the increased mutation rate at CAN1 (6 to 21 -fold) correlates with the underlying recombination rate at the locus. Importantly, we show that the elevated mutation rate is fully dependent upon Spo11, the protein that introduces the meiosis specific DSBs. To examine associated recombination we selected for random spores with or without a mutation in CAN1. We find that the mutations isolated this way show an increased association with recombination (crossovers, loss of crossover interference and/or increased gene conversion tracts). Polζ appears to contribute about half of the mutations induced during meiosis, but is not the only source of mutations for the meiotic effect. We see no difference in either the spectrum or distribution of mutations between mitosis and meiosis. The correlation of hotspots with elevated mutagenesis provides a mechanism for organisms to control evolution rates in a gene specific manner.

  18. Hybridization alters spontaneous mutation rates in a parent-of-origin-dependent fashion in Arabidopsis.

    Science.gov (United States)

    Bashir, Tufail; Sailer, Christian; Gerber, Florian; Loganathan, Nitin; Bhoopalan, Hemadev; Eichenberger, Christof; Grossniklaus, Ueli; Baskar, Ramamurthy

    2014-05-01

    Over 70 years ago, increased spontaneous mutation rates were observed in Drosophila spp. hybrids, but the genetic basis of this phenomenon is not well understood. The model plant Arabidopsis (Arabidopsis thaliana) offers unique opportunities to study the types of mutations induced upon hybridization and the frequency of their occurrence. Understanding the mutational effects of hybridization is important, as many crop plants are grown as hybrids. Besides, hybridization is important for speciation and its effects on genome integrity could be critical, as chromosomal rearrangements can lead to reproductive isolation. We examined the rates of hybridization-induced point and frameshift mutations as well as homologous recombination events in intraspecific Arabidopsis hybrids using a set of transgenic mutation detector lines that carry mutated or truncated versions of a reporter gene. We found that hybridization alters the frequency of different kinds of mutations. In general, Columbia (Col)×Cape Verde Islands and Col×C24 hybrid progeny had decreased T→G and T→A transversion rates but an increased C→T transition rate. Significant changes in frameshift mutation rates were also observed in some hybrids. In Col×C24 hybrids, there is a trend for increased homologous recombination rates, except for the hybrids from one line, while in Col×Cape Verde Islands hybrids, this rate is decreased. The overall genetic distance of the parents had no influence on mutation rates in the progeny, as closely related accessions on occasion displayed higher mutation rates than accessions that are separated farther apart. However, reciprocal hybrids had significantly different mutation rates, suggesting parent-of-origin-dependent effects on the mutation frequency.

  19. Sigma virus and mutation in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Paquin, S.L.A.

    1977-01-01

    - The objectives of these experiments have been (1) to verify and evidence more fully the action of sigma in causing recessive lethal mutation on the X chromosome of Drosophila, both in the male and the female germ line; (2) to extend the study of sigma-induced recessive lethal mutation to the Drosophila autosomes; (3) to explore the possibility that this mutagenesis is site-directed; (4) to study the effects of sigma virus in conjunction with radiation in increasing non-disjunction and dominant lethality. The virus increases the rate of radiation-induced nondisjunction by altering meiotic chromosomal behavior. Percentage of non-disjunction with 500 rads of x-rays in the virus-free flies was 0.176, while in sigma-containing lines it was 0.333. With high doses of either x or neutron radiation, the presence of the virus enhances the frequency of dominant lethality. The difference is especially significant with the fast neutrons. The results indicate that sigma, and presumably other viruses, are indeed environmental mutagens and are, therefore, factors in the rate of background or spontaneous mutation

  20. Radiation mutagenesis from molecular and genetic points of view

    International Nuclear Information System (INIS)

    Chen, D.J.C.; Park, M.S.; Okinaka, R.T.; Jaberaboansari, A.

    1993-01-01

    An important biological effect of ionizing radiation on living organisms is mutation induction. Mutation is also a primary event in the etiology of cancer. The chain events, from induction of DNA damage by ionizing radiation to processing of these damages by the cellular repair/replication machinery, that lead to mutation are not well understood. The development of quantitative methods for measuring mutation-induction, such as the HPRT system, in cultured mammalian cells has provided an estimate of the mutagenic effects of x- and γ-rays as wen as of high LET radiation in both rodent and human cells. A major conclusion from these mutagenesis data is that high LET radiation induces mutations more efficiently than g-rays. Molecular analysis of mutations induced by sparsely ionizing radiation have detected major structural alterations at the gene level. Our molecular results based on analysis of human HPRT deficient mutants induced by γ-rays, α-particles and high energy charged particles indicate that higher LET radiation induce more total and large deletion mutations than γ-rays. Utilizing molecular techniques including polymerase chain reaction (PCR), Single-strand conformation polymorphism (SSCP), denaturing gradient gel electrophoresis (DGGE) and Direct DNA sequencing, mutational spectra induced by ionizing radiation have been compared in different cell systems. Attempts have also been made to determine the mutagenic potential and the nature of mutation induced by low dose rate γ-rays. Defective repair, in the form of either a diminished capability for repair or inaccurate repair, can lead to increased risk of heritable mutations from radiation exposure. Therefore, the effects of DNA repair deficiency on the mutation induction in mammalian cells is reviewed

  1. Study of the effect of dose-rate on radiation-induced damage to human erythrocytes

    Energy Technology Data Exchange (ETDEWEB)

    Krokosz, Anita [Department of Molecular Biophysics, University of Lodz, Banacha 12/16, Lodz (Poland)]. E-mail: krokosz@biol.uni.lodz.pl; Koziczak, Renata [Department of Molecular Biophysics, University of Lodz, Banacha 12/16, Lodz (Poland); Gonciarz, Marta [Department of Molecular Biophysics, University of Lodz, Banacha 12/16, Lodz (Poland); Szweda-Lewandowska, Zofia [Department of Molecular Biophysics, University of Lodz, Banacha 12/16, Lodz (Poland)

    2006-01-15

    Human erythrocytes suspended in an isotonic Na-phosphate buffer, pH 7.4 (hematocrit of 2%) were irradiated with {gamma}-rays at three dose-rates of 66.7, 36.7, 25 Gy min{sup -1} in order to investigate the influence of the dose-rate on radiation-induced membrane damage, hemoglobin oxidation and loss of reduced glutathione. The obtained results showed that such processes as erythrocyte hemolysis, lipid and protein destruction depend on the radiation dose-rate. The parameter values describing these processes showed an inverse dose-rate effect.

  2. Study of the effect of dose-rate on radiation-induced damage to human erythrocytes

    International Nuclear Information System (INIS)

    Krokosz, Anita; Koziczak, Renata; Gonciarz, Marta; Szweda-Lewandowska, Zofia

    2006-01-01

    Human erythrocytes suspended in an isotonic Na-phosphate buffer, pH 7.4 (hematocrit of 2%) were irradiated with γ-rays at three dose-rates of 66.7, 36.7, 25 Gy min -1 in order to investigate the influence of the dose-rate on radiation-induced membrane damage, hemoglobin oxidation and loss of reduced glutathione. The obtained results showed that such processes as erythrocyte hemolysis, lipid and protein destruction depend on the radiation dose-rate. The parameter values describing these processes showed an inverse dose-rate effect

  3. Induced mutations in highly heterozygous vegetatively propagated grasses

    International Nuclear Information System (INIS)

    Powell, J.B.

    1976-01-01

    Experience with mutation induction of turf and forage grasses indicates that much progress can be achieved by this method. More than 300 mutations have been produced in our laboratory in the cultivars Tifgreen and Tifdwarf bermudagrass (Cynodon sp.). In the Tifway and Tifcote bermudagrasses we have demonstrated similar mutation responses. The first three clones are triploids and Tifcote is a probable tetraploid. No seeds are set on these clones. Two clones of bermudagrass, Coastal and Coastcross-1, occupy millions of hectares in the USA. Both are mutable and are known to be hybrids with 36 chromosomes. Biotypes of dallisgrass (Paspalum dilatatum Poir.) exist with 40 and 50 chromosomes and reproduce as sexual and obligate apomictic forms. Gamma-ray and thermal-neutron treatment of seed of these biotypes produced mutants that maintained the maternal characteristics in subsequent generations. Bahiagrass (Paspalum notatum Fluegge) also has sexual and apomictic biotypes. Some success was indicated for increased seed set by mutagen treatment. Kentucky bluegrass (Poa pratensis L.) is a facultative apomict with varying numbers of chromosomes in different cultivars. Gamma-ray mutagen treatment of rhizomes produced numerous mutations for plant type and disease reaction. Most mutations perpetuate themselves through the seed. The characteristic in common with all these grasses is their heterozygosity, which is maintained by the vegetative propagation or apomictic mode of reproduction. The experience in using ionizing radiation to induce heritable changes in these vegetatively propagated grasses is one of considerable success. Mutation rates in some of these irradiated grasses exceeded 65% and aberrant plants with characteristics previously never observed were found. Numerous hemizygous and heterozygous loci seem to be a sensitive target for mutagens. (author)

  4. Influence of mutations in some structural genes of heat-shock proteins on radiation resistance of Escherichia coli

    International Nuclear Information System (INIS)

    Verbenko, V.N.; Kuznetsova, L.V.; Bikineeva, E.G.; Kalinin, V.L.

    1992-01-01

    Lethal effects of γ-irradiation were studied in Escherichia coli strains with normal repair genotype and in radiation-resistant Gam r strains, both carrying additional mutations in the structural genes dnaK, grpE, groES or groEL. The null mutation ΔdnaK52::Cm r enhanced radiation sensitivity of wild-type cells and abolished the effect of heat induced rediation-resistance (ETIRR) and elevated radiation resistance of the Gam r strains

  5. The role of radiation types and dose in induced genomic instability

    International Nuclear Information System (INIS)

    Kadhim Munira, A.

    2007-01-01

    Complete text of publication follows. Genomic Instability (GI) is defined as long-term alterations induced by low-dose exposure to a variety of genotoxic agents in mammalian cells that act to increase the 'apparent' spontaneous mutation frequency.GI is a hallmark of tumorigenic progression and is observed in the progeny of irradiated and bystander cells as the delayed and stochastic appearance of de novo chromosomal aberrations, gene mutations and delayed lethal mutations both in vitro and in vivo. It occurs at a frequency several orders of magnitude greater than would be expected for mutation in a single gene, implying that GI is a multigenic phenomenon. The expression of GI can be influenced by genotype, cell type and radiation quality; however the underlying mechanisms are not fully understood. While several studies have demonstrated GI induction by high and low LET radiation, our work on human and mouse primary cell systems has shown significant differences in the capacity to induce GI and the spectrum of alterations depending on LET. These differences might be attributed to differences in radiation track structure, radiation dose and radiation exposure regime (distribution of hit and un hit cells). In this presentation I shall review the role of radiation quality; describe the possible mechanisms underlining the observed differences between radiation type and present results of experiments demonstrating that the dose of low LET radiation might be the most significant factor in determining the role of radiation type in the induction of GI.

  6. The induction of somatic mutations by high-LET radiation observed using the Drosophila assay system

    International Nuclear Information System (INIS)

    Yoshikawa, Isao; Takatsuji, Toshihiro; Nagano, Masaaki; Hoshi, Masaharu; Takada, Jun; Endo, Satoru

    1999-01-01

    To evaluate the mutagenic potential of high-LET radiation, an analysis was made on the production of somatic mutations by 252 Cf fission neutron s and heavy particle ions accelerated by a synchrotron. A Drosophila strain that allows simultaneous detection of two types of mutations in an identical fly was constructed. One was a wing-hair mutation and the other was an eye-color mosaic spot mutation. Measurements were made using a combined assay system of both mutation assays. Larvae were exposed to radiation at the age of post-ovipositional day-3. The efficiency of 252 Cf neutrons for inducing wing-hair mosaic spots was very high, the relative biological effectiveness (RBE) = 8.5, but the efficiency for eye-color mosaic spot was nearly equal (RBE = 1.2) to that of 137 Cs γ-rays. The RBE of carbon ions for inducing wing-hair mosaic spots increased as an increase in LET values. The RBE for the induction of eye-color mutants did not change with LET. These relationships suggest that more complex types of DNA damages such as non-rejoinable strand break or clustered double strand break, which increase with LET may be responsible for the induction of wing-hair mutation, while simpler forms of molecular damage may induce a reversion in the white-ivory allele. (M.N.)

  7. Risk of radiation-induced cancer at low doses and low dose rates for radiation protection purposes

    International Nuclear Information System (INIS)

    1995-01-01

    The aim of this report is to provide an updated, comprehensive review of the data available for assessing the risk of radiation-induced cancer for radiation protection purposes. Particular emphasis is placed on assessing risks at low doses and low dose rates. The review brings together the results of epidemiological investigations and fundamental studies on the molecular and cellular mechanisms involved in radiation damage. Additionally, this information is supplemented by studies with experimental animals which provide further guidance on the form of the dose-response relationship for cancer induction, as well as on the effect of dose rate on the tumour yield. The emphasis of the report is on cancer induction resulting from exposure to radiations with a low linear energy transfer (LET). The work was performed under contract for the Institut de Protection et de Surete Nucleaire, Fontenay-aux-Roses, Paris, France, whose agreement to publish is gratefully ackowledged. It extends the advice on radiation risks given in Documents of the NRPB, 4 No. 4 (1993). (Author)

  8. Hit-size effectiveness theory applied to high doses of low LET radiation for pink mutations in Tradescantia

    International Nuclear Information System (INIS)

    Varma, M.N.; Bond, V.P.; Matthews, G.

    1985-01-01

    A hit-size effectiveness function which represents the probability of inducing a pink mutation in Tradescantia as a function of lineal energy density has been obtained (1) using observed pink mutation data for seven different radiation qualities and their respective single event microdosimetric spectra. In obtaining this function only the linear portions of dose-response curves were used. A significant improvement of the concepts embodied in the proposed hit-size effectiveness theory would be the demonstration of its applicability at high doses (where multiple hits are produced) and high dose rates (at which no significant biological repair takes place). In this article details are given on preliminary calculations of the pink mutation frequency in Tradescantia at 1, 5, 10, 20, and 60 rads for 250 kVp x rays, using the multi-hit spectra and the hit-size effectiveness function obtained on the basis of single hit microdosimetric spectra as outline in (1). A comparison of the calculated and observed pink mutation frequencies indicate excellent agreement and suggests the possibility of obtaining the hit-size effectiveness function from high dose biological-effect data obtained using low-LET radiations. 6 refs., 3 figs., 3 tabs

  9. Radiation-induced mutation breeding of papaya

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Y. K. [Horticulture Research Centre, Malaysian Agricultural Research and Development Institute (MARDI), Kuala Lumpur (Malaysia)

    2009-05-15

    Irradiation-induced mutation breeding of papaya commenced at the Malaysian Agricultural Research and Development Institute (MARDI) in August, 2000. This research was initiated under a Coordinated Research Project (CRP - D23023) with assistance from the International Atomic Energy Agency (IAEA). In the preliminary dosimetry study, seeds from two local papaya varieties, Sekaki and Eksotika were irradiated, either as dry seeds or as pre-soaked seeds (soaked overnight in water and surface-dried) with radiation doses ranging from 0 to 300 Gy. 100 Gy dose was lethal for all wet presoaked seeds while dry seed did not show loss of viability, even at 300 Gy. From the growth data it was estimated that dose of 525 Gy reduced shoot elongation by 50%, and this dose was recommended for mass irradiation of dry seeds. For wet, pre-soaked seeds results indicated that 42.5 Gy was the optimal dose for mass irradiation. At this dose, both seeds germination and seedlings growth were reduced by 50%. In a massive irradiation experiment 2,000 Eksotika seeds were irradiated at 42.5 Gy (pre-soaked) and another 2,000 at 525 Gy (dry). In the M2 population, numerous physiological defects were observed, including stem splitting, leaf variegation and puckering, and crinkled dwarfs. In the M3 population, a wide variability was recorded for a number of traits. M3 seedlings derived from presoaked seeds irradiated a low 42.5 Gy dose presented a high number of plants that were shorter and more vigorous in leaf development compared to those irradiated at 525 Gy and to non-irradiated control seedlings. The distribution patterns of M3 progenies for nine quantitative field characters showed great variation, often exceeding the limits of the control population. There appears to be good prospects in improving Eksotika papaya especially in the development of dwarf trees with lower fruit bearing stature, higher total soluble solids in fruits and larger fruit size. Several M2 and M3 putative mutants also

  10. X-ray-induced bystander response reduce spontaneous mutations in V79 cells

    International Nuclear Information System (INIS)

    Maeda, Munetoshi; Kobayashi, Katsumi; Matsumoto, Hideki; Usami, Noriko; Tomiya, Masanori

    2013-01-01

    The potential for carcinogenic risks is increased by radiation-induced bystander responses; these responses are the biological effects in unirradiated cells that receive signals from the neighboring irradiated cells. Bystander responses have attracted attention in modern radiobiology because they are characterized by non-linear responses to low-dose radiation. We used a synchrotron X-ray microbeam irradiation system developed at the Photon Factory, High Energy Accelerator Research Organization, KEK, and showed that nitric oxide (NO)-mediated bystander cell death increased biphasically in a dose-dependent manner. Here, we irradiated five cell nuclei using 10 × 10 µm 2 5.35 keV X-ray beams and then measured the mutation frequency at the hypoxanthine-guanosine phosphoribosyl transferase (HPRT) locus in bystander cells. The mutation frequency with the null radiation dose was 2.6 × 10 -5 (background level), and the frequency decreased to 5.3 × 10 -6 with a dose of approximately 1 Gy (absorbed dose in the nucleus of irradiated cells). At high doses, the mutation frequency returned to the background level. A similar biphasic dose-response effect was observed for bystander cell death. Furthermore, we found that incubation with 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO), a specific scavenger of NO, suppressed not only the biphasic increase in bystander cell death but also the biphasic reduction in mutation frequency of bystander cells. These results indicate that the increase in bystander cell death involves mechanisms that suppress mutagenesis. This study has thus shown that radiation-induced bystander responses could affect processes that protect the cell against naturally occurring alterations such as mutations. (author)

  11. Influence of cigarette smoke and green tea on radiation-induced micronucleated polychromatic erythrocytes

    International Nuclear Information System (INIS)

    Gao Yong; Hao Enzhu; Ni Yanbo

    2006-01-01

    Objective: To observe the effects of cigarette smoke and green tea on radiation-induced bone marrow cell mutation, and to provide scientific information for prevention and treatment of radiation damage. Methods: There were 8 groups in the factorial experiment design with 3 factors at 2 levels. Mice were randomly divided into each group. There were 8 mice in each group. Mice in seven experimental groups were exposed to cigarette smoke, green tea, radiation or their mixtures respectively. One group was treated as the blank control group. The frequencies of micrnucleated polychromatic erythrocytes (MPCE) were scored by single blinded method. The data were analyzed with factorial experiments analysis of variance using SAS 8.0. Results: Analysis of variance showed that radiation, cigarette smoke and green tea were independently significant factors (P<0.01). Interactions between cigarette smoke and radiation or between green tea and radiation were statistically significant (P<0.01). Conclusion: Radiation and cigarette smoke can cause bone marrow cell mutations independently. There is synergistic effect between cigarette smoke and radiation. Green tea can inhibit radiation-induced cell mutation. (authors)

  12. Modification of radiation-induced sex-linked recessive lethal mutation frequency by tocopherol

    International Nuclear Information System (INIS)

    Beckman, C.; Roy, R.M.; Sproule, A.

    1982-01-01

    The present study evaluates the effect of supplementing culture medium with α-tocopherol acetate on the yield of sex-linked recessive lethal mutants induced by X-irradiation in mature sperm of Drosophila. Although tocopherol treatment of males had no impact on the yield of mutations, a drastic reduction in mutation frequency was observed when irradiated males were mated to females raised and subsequently maintained on tocopherol-enriched diet. (orig./MG)

  13. Molecular and genetic characterization of a radiation-induced structural rearrangement in mouse chromosome 2 causing mutations at the limb deformity and agouti loci

    International Nuclear Information System (INIS)

    Woychik, R.P.; Generoso, W.M.; Russell, L.B.; Cain, K.T.; Cacheiro, N.L.; Bultman, S.J.; Selby, P.B.; Dickinson, M.E.; Hogan, B.L.

    1990-01-01

    Molecular characterization of mutations in the mouse, particularly those involving agent-induced major structural alterations, is proving to be useful for correlating the structure and expression of individual genes with their function in the whole organism. Here we present the characterization of a radiation-induced mutation that simultaneously generated distinct alleles of both the limb deformity (ld) and agouti (a) loci, two developmentally important regions of chromosome 2 normally separated by 20 centimorgans. Cytogenetic analysis revealed that an interstitial segment of chromosome 17 (17B- 17C; or, possibly, 17A2-17B) had been translocated into the distal end of chromosome 2, resulting in a smaller-than-normal chromosome 17 (designated 17del) and a larger form of chromosome 2 designated 2(17). Additionally, a large interstitial segment of the 2(17) chromosome, immediately adjacent and proximal to the insertion site, did not match bands 2E4-2H1 at corresponding positions on a normal chromosome 2. Molecular analysis detected a DNA rearrangement in which a portion of the ld locus was joined to sequences normally tightly linked to the a locus. This result, along with the genetic and cytogenetic data, suggests that the alleles of ld and a in this radiation-induced mutation, designated ldIn2 and ajIn2, were associated with DNA breaks caused by an inversion of an interstitial segment in the 2(17) chromosome

  14. What kind of prior low dose radiation does the adaptive response induce?

    International Nuclear Information System (INIS)

    Suzuki, Masao

    2009-01-01

    Described are the adaptive response (AR) and genetic instability (GI) induced by different kind of low dose radiation (LDR) and their relation with the bystander effect. For this, human normal cells were placed at 2.65 m distance from the target of National Institute of Radiological Sciences (NIRS) Heavy Ion Medical Accelerator in Chiba (HIMAC) to see the biological effect of LDR of mixed radiations (1-1.5 mGy/day; mixture of 94% gamma ray, 1.9% neutron (N) and particle ions mainly containing proton (P) in the rest). Cells were then irradiated with 1.5 Gy X-ray. No effect on the lethality was observed as compared with control cells without LDR. The mutation on hprt gene was found significantly elevated 2-30 days after LDR, suggesting that GI had been induced. To see the effect of each radiation on GI, gamma ray ( 137 Cs), N ( 241 Am-Be) and heavy ion (HIMAC He, C and Fe) as LDR were separately irradiated to cells with total 1 mGy/7-8 hr and then acutely with the X-ray. He and C ions were found to promote mutation 1.9 and 4.0 times higher on frequencies, respectively, and N, to reduce the mutation rate to 15% (AR). Results indicated that cell responses were quite different dependently on linear energy transfer. The probability of hit number of ions in the cell population was calculated to be 61, 15 and 2% for He, C and Fe, respectively, suggesting an existence of considerable number of cells not irradiated. Presence of a gap-junction specific inhibitor (GSI) at LDR resulted in normalization of mutation rate in all groups of cells, suggesting that the bystander effect through cell-cell signal transduction affected the cell response to X-irradiation. For AR induction by N, when 1.5% of cells in culture were irradiated by P in NIRS SPICE as LDR, AR in mutation was observed and was inhibited by GSI, suggesting that N completely destroyed the hit cell but concomitantly yielded recoil P substantially acted as LDR. Above findings indicated that the exact radiation risk can

  15. Spectrum and Frequency of Mutations Induced by Gamma Radiations in Three Varieties of Nigerian Sesame (Sesamum indicum L.

    Directory of Open Access Journals (Sweden)

    Muhammad Liman MUHAMMAD

    2018-03-01

    Full Text Available Insufficient genetic variability is one of the major problems of plant breeding programmes, especially in sesame. Gamma radiation has been reported to be very effective in creating genetic variability in plants. Three varieties of Nigerian sesame were assessed for spectrum and frequency of mutation induced by Gamma radiations in M1 and M2 generations. The varieties (NCRIBEN-04E, NCRIBEN-01M and NCRIBEN-03L were treated with four different doses of gamma rays (250, 350, 450 and 550 Gy. The treated and untreated seeds (control were sown in planting bags (under field condition to raise M1 plants. Four treatments: V1D5, V2D3, V3D2 and V3D4 (from M1 plants were selected and bulked to obtain M2 populations. The results of M1 revealed four mutant fruit traits: multicarpellate capsule, multiple capsule per leaf axil, indehiscent capsule and terminal capsules. The highest frequencies of the traits in M1 generation were 2.50×10-2, 9.17×10-2, 1.67×10-2and3.33×10-2 respectively. The highest branching (7 was from NCRIBEN-01M, while the least (2 was from NCRIBEN-04E. The M2 plants were grouped into eight M2 lines. The dose range (250-550 Gy was proved to be effective in inducing viable mutations in sesame.

  16. Mutagenicity of monoadducts and cross-links induced in Aspergillus nidulans by 8-methoxypsoralen plus 365 nm radiation

    International Nuclear Information System (INIS)

    Scott, B.R.; Maley, M.A.

    1981-01-01

    8-Methoxypsoralen plus 365 nm radiation induces mutation at the methionine supressor loci of Aspergillus inhibitor-deficient conidia at low doses of near-UV radiation with one-hit kinetics and at higher near-UV radiation doses with two-hit kinetics. These results and others suggest that both monoadducts and cross-links, formed by 8-methoxypsoralen and DNA upon exposure to UV radiation, are capable of inducing mutation. Evidence is also presented that induced furocoumarin cross-links are responsible for the inactivation of the Aspergillus conidium. (author)

  17. Lack of chemically induced mutation in repair-deficient mutants of yeast

    International Nuclear Information System (INIS)

    Prakash, L.

    1974-01-01

    Two genes, rad6 and rad9, that confer radiation sensitivity in the yeast Saccharomyces cerevisiae also greatly reduce the frequency of chemically-induced reversions of a tester mutant cyc1-131, which is a chain initiation mutant in the structural gene determining iso-1-cytochrome c. Mutations induced by ethyl methanesulfonate (EMS), diethyl sulfate (DES), methyl methanesulfonate (MMS), dimethyl sulfate (DMS), nitroquinoline oxide (NQO), nitrosoguanidine (NTG), nitrogen mustard (HN2), β-propiolactone, and tritiated uridine, as well as mutations induced by ultraviolet light (UV) and ionizing radiation were greatly diminished in strains homozygous for either the rad6 or rad9 gene. Nitrous acid and nitrosoimidazolidone (NIL), on the other hand, were highly mutagenic in these repair-deficient mutants, and at low doses, these mutagens acted with about the same efficiency as in the normal RAD strain. At high doses of either nitrous acid or NIL, however, reversion frequencies were significantly reduced in the two rad mutants compared to normal strains. Although both rad mutants are immutable to about the same extent, the rad9 strains tend to be less sensitive to the lethal effect of chemical mutagens than rad6 strains. It is concluded that yeast requires a functional repair system for mutation induction by chemical agents. (auth)

  18. Lack of chemically induced mutation in repair-deficient mutants of yeast.

    Science.gov (United States)

    Prakash, L

    1974-12-01

    Two genes, rad6 and rad9, that confer radiation sensitivity in the yeast Saccharomyces cerevisiae also greatly reduce the frequency of chemically-induced reversions of a tester mutant cyc1-131, which is a chain initiation mutant in the structural gene determining iso-1-cytochrome c. Mutations induced by ethyl methanesulfonate (EMS), diethyl sulfate (DES), methyl methanesulfonate (MMS), dimethyl sulfate (DMS), nitroquinoline oxide (NQO), nitrosoguanidine (NTG), nitrogen mustard (HN2), beta-propiolactone, and tritiated uridine, as well as mutations induced by ultraviolet light (UV) and ionizing radiation were greatly diminished in strains homozygous for either the rad6 or rad9 gene. Nitrous acid and nitrosoimidazolidone (NIL), on the other hand, were highly mutagenic in these repair-deficient mutants, and at low doses, these mutagens acted with about the same efficiency as in the normal RAD strain. At high doses of either nitrous acid or NIL, however, reversion frequencies were significantly reduced in the two rad mutants compared to normal strains. Although both rad mutants are immutable to about the same extent, the rad9 strains tend to be less sensitive to the lethal effect of chemical mutagens than rad6 strains. It is concluded that yeast requires a functional repair system for mutation induction by chemical agents.

  19. Molecular mechanisms of induced-mutations

    International Nuclear Information System (INIS)

    Kato, Takeshi

    1985-01-01

    The outcome of recent studies on mechanisms of induced-mutations is outlined with particular emphasis on the dependence of recA gene function in Escherichia coli. Genes involved in spontaneous mutation and x-ray- and chemical-induced mutation and genes involved in adaptive response are presented. As for SOS mutagenesis, SOS-induced regulation mechanisms and mutagenic routes are described. Furthermore, specificity of mutagens themselves are discussed in relation to mechanisms of base substitution, frameshift, and deletion mutagenesis. (Namekawa, K.)

  20. Plant breeding: Induced mutation technology for crop improvement

    International Nuclear Information System (INIS)

    Novak, F.J.; Brunner, H.

    1992-01-01

    Plant breeding requires genetic variation of useful traits for crop improvement, but the desired variation is often lacking. Mutagenic agents, such as radiation and certain chemicals, can be used to induce mutations and generate genetic variations from which desirable mutants may be selected. After a brief summary of the methods currently employed in plant breeding, especially those inducing genetic engineering, this article describes the activities of the Plant Breeding Unit of the IAEA Laboratories at Seibersdorf, summarizing the research and development areas currently being pursued. The banana plant is chosen to exemplify the Laboratories' research

  1. Mutations induced by ultraviolet light

    International Nuclear Information System (INIS)

    Pfeifer, Gerd P.; You, Young-Hyun; Besaratinia, Ahmad

    2005-01-01

    The different ultraviolet (UV) wavelength components, UVA (320-400 nm), UVB (280-320 nm), and UVC (200-280 nm), have distinct mutagenic properties. A hallmark of UVC and UVB mutagenesis is the high frequency of transition mutations at dipyrimidine sequences containing cytosine. In human skin cancers, about 35% of all mutations in the p53 gene are transitions at dipyrimidines within the sequence 5'-TCG and 5'-CCG, and these are localized at several mutational hotspots. Since 5'-CG sequences are methylated along the p53 coding sequence in human cells, these mutations may be derived from sunlight-induced pyrimidine dimers forming at sequences that contain 5-methylcytosine. Cyclobutane pyrimidine dimers (CPDs) form preferentially at dipyrimidines containing 5-methylcytosine when cells are irradiated with UVB or sunlight. In order to define the contribution of 5-methylcytosine to sunlight-induced mutations, the lacI and cII transgenes in mouse fibroblasts were used as mutational targets. After 254 nm UVC irradiation, only 6-9% of the base substitutions were at dipyrimidines containing 5-methylcytosine. However, 24-32% of the solar light-induced mutations were at dipyrimidines that contain 5-methylcytosine and most of these mutations were transitions. Thus, CPDs forming preferentially at dipyrimidines with 5-methylcytosine are responsible for a considerable fraction of the mutations induced by sunlight in mammalian cells. Using mouse cell lines harboring photoproduct-specific photolyases and mutational reporter genes, we showed that CPDs (rather than 6-4 photoproducts or other lesions) are responsible for the great majority of UVB-induced mutations. An important component of UVB mutagenesis is the deamination of cytosine and 5-methylcytosine within CPDs. The mutational specificity of long-wave UVA (340-400 nm) is distinct from that of the shorter wavelength UV and is characterized mainly by G to T transversions presumably arising through mechanisms involving oxidized DNA

  2. Influence of radiation exposure rate on somatic mutation frequency and loss of reproductive integrity in tradescantia stamen hairs

    International Nuclear Information System (INIS)

    Ichikawa, S.; Nauman, C.H.; Sparrow, A.H.; Takahashi, C.S.

    1978-01-01

    Inflorescences of Tradescantia clone 02 (2n=12), hetero- or hemi-zygous for flower color, were exposed to a series of γ-ray exposures at two different exposure rates, 29.3 R/min and 0.026-0.52 R/min. Pink mutation-response curves, and survival curves based on reproductive integrity, were constructed for each of the exposure rates. Loss of reproductive integrity was also assessed at high (256 R/min) and low (0.52-4.17 R/min) γ-ray exposure rates in T. blossfeldiana (2n=72). All observations were made on stamen hairs. The higher exposure rate was 1.3-1.7 times more effective in inducing pink mutations in clone 02. A greater efficiency of the higher exposure rate was also found for both taxa at the loss of reproductive integrity endpoint. The D 0 values obtained at the higher exposure rates, 154 R for clone 02 and 720 R for T. blossfeldiana, were significantly lower than the corresponding values of 270 R and 1880 R obtained at the lower exposure rates. These D 0 's differ by factors of 1.75 and 2.61 for clone 02 and T. blossfeldiana, respectively. D 0 's for the two taxa were found to be inversely correlated with their interphase chromosome volumes. (Auth.)

  3. Radiation-induced genomic instability, and the cloning and functional analysis of its related gene

    International Nuclear Information System (INIS)

    Muto, Masahiro; Kanari, Yasuyoshi; Kubo, Eiko; Yamada, Yutaka

    2000-01-01

    Exposure to ionizing radiation produces a number of biological consequences including gene mutations, chromosome aberrations, cellular transformation and cell death. The classical view has been that mutations occur at the sites of DNA damage, that is, damage produced by radiation is converted into a mutation during subsequent DNA replication or as a consequence of enzymatic repair processes. However, many investigators have presented evidence for an alternative mechanism to explain these biological effects. This evidence suggests that radiation may induce a process of genomic instability that is transmissible over many generations of cell replication and that serves to enhance the probability of the occurrence of such genetic effects among the progeny of the irradiated cell after many generations of cell replication. If such a process exists in vivo, it could have significant implications for mechanisms of carcinogenesis. Exposure of B10 mice to fractionated X-irradiation induces a high incidence of thymic lymphomas, whereas the incidence in STS/A mice is very low. Such strain differences are presumably determined genetically, and various genetic factors have been reported to be involved in radiation-induced lymphomagenesis. The mechanism of radiation-induced lymphomagenesis appears to develop through a complex and multistep process. Using this experimental system, we characterized the prelymphoma cells induced by radiation, and identified the genetic changes preceding the development of thymic lymphomas by comparing the oncogenic alterations with the pattern of T cell receptor (TCR) γ rearrangements. In these studies, the latent expression of some chromosomal aberrations and p53 mutations in irradiated progeny has been interpreted to be a manifestation of genomic instability. In the present report we review the results of in vivo studies conducted in our laboratory that support the hypothesis of genomic instability induced by radiation, and we describe the

  4. The shapes of the radiation dose-mutation response curves in drosophila: Mechanisms and implications

    International Nuclear Information System (INIS)

    Abrahamson, S.; DeJongh, C.; Meyer, H.U.

    1981-01-01

    This chapter proposes that radiation induced mutations, namely sex-linked recessive lethals in Drosophila and forward mutations at specific loci in Drosophila, mammals and lower eucaryotes, are the result of two sub-lesions or hits, induced by either single ionization tracks or by the interaction of two independent tracks for low LET radiations, when the dose is delivered in an acute fashion. Utilizes the well recognized linear quadratic expression Y=C+αD+βD 2 , where C is the spontaneous frequency of events scored and α and β represent the coefficients of the dose. Concludes that for low LET radiations, X or gamma rays, the linear-quadratic model can be used to predict the genetic response of germ cells and somatic cells to a variety of radiation regimes. Points out that the point of inflection in the curve, α/β value, can be determined specifically by target dimensions which vary with respect to DNA content. Considers the difference in RBE values observed for different species to be a reflection of their different target sizes

  5. Use of induced mutations for cotton breeding in India

    International Nuclear Information System (INIS)

    Raut, R.N.

    1980-01-01

    A large number of studies have been reported in recent years on the use of induced mutations in the improvement of food crops and ornamentals. Similar investigations on fibre crops like cotton have, however, been relatively few. The fact that most of the economically useful characters in cotton are under polygenic control appears to be the main limiting factor. Inspite of this there are reports of radiation induced useful mutations used as commercial varieties. As early as 1950 a X-ray induced mutant variety of G. hirsutum cotton Indore-2 was released for commercial cultivation in Madhya Pradesh and covered more than one lac hectares. More recently an early maturing mutant variety MCU-7 was released for cultivation in summer rice fallows of Tamil Nadu and covers nearly 10,000 acres. Other promising mutant strains found suitable b.v large scale trials and recommended for cultivation under specific conditions are Okra leaf mutant, photoinsensitive mutant of MCU-5 (named Rasmi) and Jassid tolerant early maturing mutant 4-1 (Pusa Ageti). In addition improved varieties like Badnaawar-1, Khandwa-2 and M64 have been evolved by utilizing mutant lines in cross breeding. The scope of induced mutation method as a breeding technique for cotton improvement in India is very wide. (author)

  6. Hereditary effects of radiation: new advances from the Scientific annex of UNSCEAR 2001 Report to the General Assembly

    International Nuclear Information System (INIS)

    Dubner, Diana L.

    2001-01-01

    The paper presents an overview of the advances in the estimation of the genetic risks of exposure to ionizing radiation. Insights gained into the molecular aspects of naturally occurring human genetic diseases, used together with mouse-data on radiation-induced mutations are allowing the framework for risk estimation to be restructured. The five important changes that are introduced include: revision of the baseline frequency of Mendelian diseases; the use of human data on spontaneous mutation rates and mouse data on induced mutation rates for Doubling Dose (DD) calculation; the development of the Mutation Component (MC) concept for predicting the impact of an increase in mutation rate on disease frequency for the different classes of genetic diseases; the introduction in the risk equation of the Potential Recoverability Correction Factor ( PRCF ) to bridge the gap between the rates of induced mutations determined in mouse studies and the risks of inducible genetic diseases in human live birth; the introduction of the concept that radiation-induced genetic damage in humans is more likely to be manifest as multisystem developmental abnormalities rather than a single-gene diseases in the progeny of irradiated parents. (author)

  7. Somatic mutation in larvae of the silkworm, Bombyx mori, induced by heavy ion irradiation to diapause eggs

    Energy Technology Data Exchange (ETDEWEB)

    Kotani, Eiji; Furusawa, Toshiharu [Kyoto Inst. of Tech. (Japan). Faculty of Textile Science; Nagaoka, Shunji [Fujita Health Univ., Toyoake, Aichi (Japan). School of Health Sciences] [and others

    2002-12-01

    In order to investigate whether eggs of the black-striped strain (P{sup S}) of the silkworm, Bombyx mori, represent an appropriate model for estimating the biological effect of cosmic radiation, radiosensitivity of the eggs against X-rays and heavy ion particles was examined as ground-based experiments. The exposure of diapause eggs to X-rays or heavy ion particles resulted in somatic mutations appearing as a white spot on the black integument during larval stage. Irradiation of non-diapause eggs with X-rays demonstrated a significant difference in frequency of the mutation between fractionated and single administration doses, but no difference was observed in diapause eggs. Incidence of the mutation as induced by carbon ion beams for 15-day old eggs was higher for eggs that had been kept at 15 deg C than those kept at 25 deg C. Neon beam irradiation of diapause eggs displayed dose- and linear energy transfer (LET)-dependent effects, causing a maximal rate of the mutation at 150 keV/{mu}m. These results confirm that B. mori eggs represent valid models for estimating the biological effects of cosmic radiation. (author)

  8. Health effect of low dose/low dose rate radiation

    International Nuclear Information System (INIS)

    Kodama, Seiji

    2012-01-01

    The clarified and non-clarified scientific knowledge is discussed to consider the cause of confusion of explanation of the title subject. The low dose is defined roughly lower than 200 mGy and low dose rate, 0.05 mGy/min. The health effect is evaluated from 2 aspects of clinical symptom/radiation hazard protection. In the clinical aspect, the effect is classified in physical (early and late) and genetic ones, and is classified in stochastic (no threshold value, TV) and deterministic (with TV) ones from the radioprotection aspect. Although the absence of TV in the carcinogenic and genetic effects has not been proved, ICRP employs the stochastic standpoint from the safety aspect for radioprotection. The lowest human TV known now is 100 mGy, meaning that human deterministic effect would not be generated below this dose. Genetic deterministic effect can be observable only in animal experiments. These facts suggest that the practical risk of exposure to <100 mGy in human is the carcinogenesis. The relationship between carcinogenic risk in A-bomb survivors and their exposed dose are found fitted to the linear no TV model, but the epidemiologic data, because of restriction of subject number analyzed, do not always mean that the model is applicable even below the dose <100 mGy. This would be one of confusing causes in explanation: no carcinogenic risk at <100 mGy or risk linear to dose even at <100 mGy, neither of which is scientifically conclusive at present. Also mentioned is the scarce risk of cancer in residents living in the high background radiation regions in the world in comparison with that in the A-bomb survivors exposed to the chronic or acute low dose/dose rate. Molecular events are explained for the low-dose radiation-induced DNA damage and its repair, gene mutation and chromosome aberration, hypothesis of carcinogenesis by mutation, and non-targeting effect of radiation (bystander effect and gene instability). Further researches to elucidate the low dose

  9. Relation between four types of radiation damage and induced repair

    International Nuclear Information System (INIS)

    Radar, M.L.

    1977-08-01

    Four strains of Escherichia coli were exposed to uv and gamma radiation. Procedures are described for mutational studies, classification of revertants, inhibition of postirradiation DNA degradation and radioresistance. Comparisons were made of induction of the error-prone repair (epr) system with four mutagens; uv radiation, near uv radiation, gamma radiation, and DNA-protein crosslinks. An increase in the number of mutations was shown in every case. The observation that induction of mutagenesis, induction of inhibition of post-irradiation DNA degradation, and induction of radioresistance are closely parallel phenomena led to the investigation of the possibility that DNA-protein crosslinks which were known mutagens were also inducers of the epr system. The significance of the results is discussed

  10. Effects of chronic low level radiation in the population residing in the high level natural radiation area in Kerala, India: employing heritable DNA mutation studies.

    Science.gov (United States)

    Ahmad, Shazia; Koya, P K M; Seshadri, M

    2013-03-18

    To study the effect of chronic low level radiation, 4040 meiosis were screened at eight microsatellite and five minisatellite (2485 and 1555 meiosis respectively) marker loci in people residing in high and normal level natural radiation areas of Kerala. Variants in the repeat length of allele were considered as mutants. Mutation rates (expressed as the number of mutations observed in the total number of meiosis) were 6.4×10(-3) (16/2485) and 2.6×10(-3) (4/1555) at microsatellite and minisatellite respectively. The germline microsatellite mutation frequency of father was 1.78 times higher at 7.52×10(-3) (8/1064) compared to 4.22×10(-3) (6/1421) of mother (P=0.292, Fisher's Exact two-sided test). The paternal and maternal mutation rates at minisatellite loci were more or less similar at 2.78×10(-3) (2/719) and 2.39×10(-3) (2/836), respectively (P=1.0, Fisher's Exact two-sided test). Higher but statistically non-significant microsatellite mutation frequency was observed in HLNRA compared to NLNRA (7.25×10(-3) vs 3.64×10(-3); P=0.547). The apparent increase in the mutation rate of microsatellite loci with the increase in radiation dose was also not statistically significant. All the four minisatellite mutation observed were from HLNRA (1198 meiosis) and no mutation was observed among 357 meiosis screened from NLNRA families. All the markers used in the present study were in the non-coding region and hence mutations in these regions may not cause adverse health effects, but the study is important in understanding the effect of chronic low level radiation. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Ionizing radiation and genetic risks. Part VIII. The concept of mutation component and its use in risk estimation for multifactorial diseases

    Energy Technology Data Exchange (ETDEWEB)

    Denniston, C. [Laboratory of Genetics, University of Wisconsin-Madison, Madison (United States); Chakraborty, R. [Human Genetics Center, University of Texas School of Public Health, P.O. Box 20334, Houston, TX (United States); Sankaranarayanan, K. [Department of Radiation Genetics and Chemical Mutagenesis, Sylvius Laboratories, Leiden University Medical Centre, Wassenaarseweg 72, 2333 AL Leiden (Netherlands)

    1998-08-31

    Multifactorial diseases, which include the common congenital abnormalities (incidence: 6%) and chronic diseases with onset predominantly in adults (population prevalence: 65%), contribute substantially to human morbidity and mortality. Their transmission patterns do not conform to Mendelian expectations. The model most frequently used to explain their inheritance and to estimate risks to relatives is a Multifactorial Threshold Model (MTM) of disease liability. The MTM assumes that: (1) the disease is due to the joint action of a large number of genetic and environmental factors, each of which contributing a small amount of liability, (2) the distribution of liability in the population is Gaussian and (3) individuals whose liability exceeds a certain threshold value are affected by the disease. For most of these diseases, the number of genes involved or the environmental factors are not fully known. In the context of radiation exposures of the population, the question of the extent to which induced mutations will cause an increase in the frequencies of these diseases has remained unanswered. In this paper, we address this problem by using a modified version of MTM which incorporates mutation and selection as two additional parameters. The model assumes a finite number of gene loci and threshold of liability (hence, the designation, Finite-Locus Threshold Model or FLTM). The FLTM permits one to examine the relationship between broad-sense heritability of disease liability and mutation component (MC), the responsiveness of the disease to a change in mutation rate. Through the use of a computer program (in which mutation rate, selection, threshold, recombination rate and environmental variance are input parameters and MC and heritability of liability are output estimates), we studied the MC-heritability relationship for (1) a permanent increase in mutation rate (e.g., when the population sustains radiation exposure in every generation) and (2) a one-time increase in

  12. Utilization of induced mutations in improving legumes in Egypt

    International Nuclear Information System (INIS)

    Abo-Hegazi, A. M. T.

    1993-01-01

    More than one hundred articles published by Egyptian research workers dealing with the improvement of some seed-legumes through radiation, radioisotopes, chemical mutagens and induced mutations are briefly summarized and discussed from the point of view of a mutation breeder working in this field since 1961. Articles on faba bean (Vicia faba L.), soybean (Glycine Max L.), lentils (Lens culinaris), chick-pea (Cicer arietinum L.), lupin (Lupinus termis), peas=pea (Pisum sativum L.), cowpea (Vigna sinensis, savi), and fenugreek-helba (Trigonella foenum gracum L.) are reviewed. A very few number of promising mutations have been induced. However, none of them are utilized neither in conventional breeding programs nor as cultivars. This may be due to the lack of central plans and organization between efforts or research work being carried in various institutions. Joint plants and cooperation between research institutions, not only in Egypt but also among the Arab countries, are required in this field which may help in closing the wide gab between production and consumption os seed legumes. (author)

  13. Ionizing radiation-induced bystander mutagenesis and adaptation: Quantitative and temporal aspects

    International Nuclear Information System (INIS)

    Zhang Ying; Zhou Junqing; Baldwin, Joseph; Held, Kathryn D.; Prise, Kevin M.; Redmond, Robert W.; Liber, Howard L.

    2009-01-01

    This work explores several quantitative aspects of radiation-induced bystander mutagenesis in WTK1 human lymphoblast cells. Gamma-irradiation of cells was used to generate conditioned medium containing bystander signals, and that medium was transferred onto naive recipient cells. Kinetic studies revealed that it required up to 1 h to generate sufficient signal to induce the maximal level of mutations at the thymidine kinase locus in the bystander cells receiving the conditioned medium. Furthermore, it required at least 1 h of exposure to the signal in the bystander cells to induce mutations. Bystander signal was fairly stable in the medium, requiring 12-24 h to diminish. Medium that contained bystander signal was rendered ineffective by a 4-fold dilution; in contrast a greater than 20-fold decrease in the cell number irradiated to generate a bystander signal was needed to eliminate bystander-induced mutagenesis. This suggested some sort of feedback inhibition by bystander signal that prevented the signaling cells from releasing more signal. Finally, an ionizing radiation-induced adaptive response was shown to be effective in reducing bystander mutagenesis; in addition, low levels of exposure to bystander signal in the transferred medium induced adaptation that was effective in reducing mutations induced by subsequent γ-ray exposures.

  14. Mutator suppression and escape from replication error-induced extinction in yeast.

    Directory of Open Access Journals (Sweden)

    Alan J Herr

    2011-10-01

    Full Text Available Cells rely on a network of conserved pathways to govern DNA replication fidelity. Loss of polymerase proofreading or mismatch repair elevates spontaneous mutation and facilitates cellular adaptation. However, double mutants are inviable, suggesting that extreme mutation rates exceed an error threshold. Here we combine alleles that affect DNA polymerase δ (Pol δ proofreading and mismatch repair to define the maximal error rate in haploid yeast and to characterize genetic suppressors of mutator phenotypes. We show that populations tolerate mutation rates 1,000-fold above wild-type levels but collapse when the rate exceeds 10⁻³ inactivating mutations per gene per cell division. Variants that escape this error-induced extinction (eex rapidly emerge from mutator clones. One-third of the escape mutants result from second-site changes in Pol δ that suppress the proofreading-deficient phenotype, while two-thirds are extragenic. The structural locations of the Pol δ changes suggest multiple antimutator mechanisms. Our studies reveal the transient nature of eukaryotic mutators and show that mutator phenotypes are readily suppressed by genetic adaptation. This has implications for the role of mutator phenotypes in cancer.

  15. Radiation-induced inheritable changes in the death-rate of cells

    International Nuclear Information System (INIS)

    Bychkovskaya, I.B.; Ochinskaya, G.K.

    1980-01-01

    By the use of an original technique (regeneration of individual lines from sister cells) it was demonstrated on various individually cultivated protozoa (Amoeba proteus, Paramecium caudatum and Climacostomum virens) that even weak direct and indirect radiation effects can induce an appreciable increase in the death-rate of descendants. After a certain dose threshold, the effect did not depend on the power of the attack and remained at the same level for as long as 3 years. The observed changes were qualitatively different from known types of inheritable changes leading to cell death

  16. Maternal effects of the scid mutation on radiation-induced transgenerational instability in mice.

    NARCIS (Netherlands)

    Hatch, T.; Derijck, A.H.A.; Black, P.D.; Heijden, G.W. van der; Boer, P. de; Dubrova, Y.E.

    2007-01-01

    The results of a number of recent studies show that mutation rates in the offspring of irradiated parents are substantially elevated, however, the effect of parental genotype on transgenerational instability remains poorly understood. Here, we have analysed the mutation frequency at an expanded

  17. Chronical influence of radiation and lead on mutation rates in plants of Arabidopsis Thaliana (L.) Heynh

    International Nuclear Information System (INIS)

    Kryukov, V.I.; Shishkin, V.A.; Sokolenko, S.F.

    1996-01-01

    Plants of Arabidopsis thaliana were grown in a laboratory conditions on the soil (black earth, chernozem) which was polluted with a radioactive isotopes of cesium, 134+137 Cs. Increase in specific activity of samples from 217 to 1025 and 2529 Bq/kg resulted in increase of embryonic mutation rate in Arabidopsis from 8.2 to 20.2 and 51.6 % respectively. Bringing Pb 2+ in a dose of 16 mg into the soil resulted in statistically significant decrease in mutation rate. Further increase of lead concentration in radioactive soils to 32, 64, 96, 160 and 320 mg/kg resulted in growth of the mutation rates in the plants which were grown on the soil with low and middle specific activity of cesium, and in decrease of the mutation rates in the plants which were grown on the soil with high specific radioactivity. The last process apparently was connected with the intensive growth in the number of sterile seeds in the pods. 19 refs.; 2 figs.; 4 tabs

  18. DNA replication in necessary for fixing induced mutations to streptomycin-resistance in UV-irradiated Escherichia coli cells

    Energy Technology Data Exchange (ETDEWEB)

    Dubinin, N P; Filippov, V D

    1986-01-01

    A suspension of E.coli cells has been subjected to UV radiation, then it has been incubated in the growth medium for 15 min. After that one of the portions was incubated with nalidixic acid (NA), and the other one without it in the presence of an antibiotic. Frequency of mutations depending on or irrespective of photoactivation, has been determined. Dependence of Str mutation fixing, induced by low UV radiation doses, on DNA synthesis is determined. Results indicate that both photoreactivation of mutations and its senstivity to mfd system are simultaneously lost.

  19. Protective effects of tea polyphenols and β-carotene against γ-radiation induced mutation and oxidative stress in Drosophila melanogaster.

    Science.gov (United States)

    Nagpal, Isha; Abraham, Suresh K

    2017-01-01

    The commonly consumed antioxidants β-carotene and tea polyphenols were used to assess their protective effects against γ-radiation induced sex-linked recessive lethal (SLRL) mutation and oxidative stress in Drosophila melanogaster . Third instar larvae and adult males of wild-type Oregon-K (ORK) were fed on test agents for 24 and 72 h respectively before exposure to 10Gy γ-irradiation. The treated/control flies were used to assess the induction of SLRLs. We also evaluated antioxidant properties of these phytochemicals in the third instar larvae. Different stages of spermatogenesis in adult males showed a decrease in γ-radiation induced SLRL frequencies upon co-treatment with test agents. A similar trend was observed in larvae. Furthermore, a significant increase in antioxidant enzymatic activities with a decrease in malondialdehyde content was observed. β-carotene and tea polyphenols have exerted antigenotoxic and antioxidant effects in Drosophila . This study demonstrated the suitability of Drosophila as an alternative to mammalian testing for evaluating the antigenotoxic and antioxidant activity of natural products.

  20. Evaluation of the recombination in somatic cells induced by radiation in different stages of Drosophila larval development

    International Nuclear Information System (INIS)

    Cruces, M.P.; Morales R, P.

    1997-01-01

    The mitotic recombination can happen spontaneously and its frequency is very low, however the recombination rate of a cell can be increased by the exposure to agents which cause damage to DNA. This type of agents are knew commonly as recombinogens. The ionizing radiation and a numerous chemical agents can be mentioned (Vogel, 1992). The objective of this work is to determine if the mutation/recombination rate induced by gamma rays varies with the development stage. In order to realize this investigation it was used the mutation and somatic recombination test of Drosophila wing (Graf and col. 1984). The mwh/ mwh and flr 3 /TM3, Ser stocks were used. (Author)

  1. Radiation-induced mutations in fish

    International Nuclear Information System (INIS)

    Schroeder, J.H.

    1980-01-01

    X-ray-induced mutations in teleostean fish were studied from the point of social behavior. A significant reduction in male aggression was found in the postirradiated F 1 generation after the irradiation of parental oogonia and spermatogonia, with 2 x 500 R (24 hr apart) of x-rays, but did not alter the aggression of F 1 females. A study on backcross generation of irradiated line fitted with a two-factor model of dominant genetic factors, high- and low-aggressive, which co-acted additively in repressing the male aggression. Social cohesiveness was compared between F 1 convict cichlides (C. nigrofasciatum) exposed by 0, 250, 500, 750, 1000, and 2000 R of x-rays. The best response was observed in males with 500 R and in females with 750 R. While an increase in cohesiveness was observed in F 1 males with 500 R, the cohesiveness of F 1 females decreased with 750 and 200 R, suggesting that the increase in male was associated with a reduction of inter-male aggression. A new ''guppy male courtship activity test'' was carried out in the offsprings of irradiated guppy, maintained in seawater and in freshwater. The mean values of both the frequency and the duration of four behavioral traits of the male guppy increased in postirradiated F 1 generation of the seawater substrain but were unchanged in that of freshwater's. In F 2 generation the mean values of the same behavioral characters decreased in both seawater and freshwater substrains. (Nakanishi, T.)

  2. Radiation carcinogenesis

    International Nuclear Information System (INIS)

    Adams, G.E.

    1987-01-01

    In this contribution about carcinogenesis induced by ionizing radiation some radiation dose-response relationships are discussed. Curves are shown of the relation between cell survival and resp. low and high LET radiation. The difference between both curves can be ascribed to endogenous repair mechanisms in the cell. The relation between single-gen mutation frequency and the surviving fractions of irradiated cells indicates that these repairing mechanisms are not error free. Some examples of reverse dose-response relationships are presented in which decreasing values of dose-rate (LET) correspond with increasing radiation induced cell transformation. Finally some molecular aspects of radiation carcinogenesis are discussed. (H.W.). 22 refs.; 4 figs

  3. Radiation induced mutations for breeding of sorghum

    Energy Technology Data Exchange (ETDEWEB)

    Bretaudeau, A [Rural Polytechnic Inst., Katibougou, Koulikoro (Mali)

    1997-07-01

    Several sorghum cultivars of Mali were irradiated with different doses of gamma rays and compared with the Caudatum types. Radio-sensitivity studies suggested that the local types were less sensitive to radiation than the introduced types. Whereas the local varieties survived dose of 300 Gy, in Caudatum types, seed germination and growth were significantly reduced at 200 Gy. Several agronomically important mutants were obtained among the progeny of the local types. Some of the mutants were shorter and had improved panicle characteristics. Radiation-induced variation was observed in several characters such as plant height, resistance to lodging, plant architecture, drought tolerance, panicle length and compactness, seed size and color, seed quality (viterous or floury) and protein content, glume color and structure, flowering data (early and late maturity), and tillering capacity. One mutant was drought tolerant. Promising mutants were selected and are presently under evaluation in the National List Trials to confirm their potential and future release. Selected variants have been also crossed with local types to obtain promising material. (author). 8 refs, 2 tabs.

  4. Radiation induced mutations for breeding of sorghum

    International Nuclear Information System (INIS)

    Bretaudeau, A.

    1997-01-01

    Several sorghum cultivars of Mali were irradiated with different doses of gamma rays and compared with the Caudatum types. Radio-sensitivity studies suggested that the local types were less sensitive to radiation than the introduced types. Whereas the local varieties survived dose of 300 Gy, in Caudatum types, seed germination and growth were significantly reduced at 200 Gy. Several agronomically important mutants were obtained among the progeny of the local types. Some of the mutants were shorter and had improved panicle characteristics. Radiation-induced variation was observed in several characters such as plant height, resistance to lodging, plant architecture, drought tolerance, panicle length and compactness, seed size and color, seed quality (viterous or floury) and protein content, glume color and structure, flowering data (early and late maturity), and tillering capacity. One mutant was drought tolerant. Promising mutants were selected and are presently under evaluation in the National List Trials to confirm their potential and future release. Selected variants have been also crossed with local types to obtain promising material. (author). 8 refs, 2 tabs

  5. Evaluation and re-evaluation of genetic radiation hazards in man

    International Nuclear Information System (INIS)

    Schalet, A.P.; Sankaranarayanan, K.

    1976-01-01

    A detailed presentation is made of the experimental data from the various systems used by Abrahamson to conclude that the per locus per rad (low LET) radiation-induced forward mutation rates in organisms whose DNA content varies by a factor of about 1000, is proportional to genome size. Additional information pertinent in this context is also reviewed. It is emphasized that the mutation rates cited by Abrahamson, although considered as pertaining to mutations at specific loci, actually derive from a broad variety of genetic end-points. It is argued that an initial (if not sufficient) condition for sound interspecific mutation rate comparisons, covering a wide range of organisms and detecting systems of various sensitivities, requires a reasonably consistent biological definition of a specific locus mutation, namely, a transmissible intralocus change. Granting the differences between systems in their resolving power to detect intergenic change, the data cited in this paper do not support the existence of a simple proportionality between radiation-induced intralocus mutation rate and genome size for the different species reviewed here

  6. Molecular analysis of radiation-induced albino (c)-locus mutations that cause death at preimplantation stages of development

    International Nuclear Information System (INIS)

    Rinchik, E.M.; Toenjes, R.R.; Paul, D.; Potter, M.D.

    1993-01-01

    Deletion mutations at the albino (c) locus have been useful for continuing the development of fine-structure physical and functional maps of the Fes-Hbb region of mouse chromosome 7. This report describes the molecular analysis of a number of radiation-induced c deletions that, when homozygous, cause death of the embryo during preimplantation stages. The distal extent of these deletions defines a locus, pid, (preimplantation development) genetically associated with this phenotype. The proximal breakpoints of eight of these deletions were mapped with respect to the Tyr (tyrosinase; albino) gene as well as to anonymous loci within the Fah-Tyr region that are defined by the Pmv-31 viral integration site and by chromosome-microdissection clones. Rearrangements corresponding to the proximal breakpoints of two of these deletions were detected by Southern blot analysis, and a size-altered restriction fragment carrying the breakpoint of one of them was cloned. A probe derived from this deletion fusion fragment defines a locus, D7Rn6, which maps within (or distal to) the pid region, and which discriminates among the distal extents of deletions eliciting the pid phenotype. Extension of physical maps from D7Rn6 should provide access both to the pid region and to loci mapping distal to pid that are defined by N-ethyl-N-nitrosourea-induced lethal mutations. 36 refs., 10 figs

  7. Induced mutations for quantitative traits in rice

    International Nuclear Information System (INIS)

    Chakrabarti, B.N.

    1974-01-01

    The characteristics and frequency of micro-mutations induced in quantitative traits by radiation treatment and the extent of heterozygotic effects of different recessive chlorophyll-mutant-genes on quantitative trait has been presented. Mutagenic treatments increased the variance for quantitative traits in all cases although the magnitude of increase varied depending on the treatment and the selection procedure adopted. The overall superiority of the chlorophyll-mutant heterozygotes over the corresponding wild homozygotes, as noted in consecutive two seasons, was not observed when these were grown at a high level of nitrogen fertiliser. (author)

  8. Effect of the uvr D3 mutation on ultraviolet radiation-induced DNA-repair replication in Escherichia coli K12

    International Nuclear Information System (INIS)

    Carlson, K.M.; Smith, K.C.

    1981-01-01

    Ultraviolet-radiation-induced DNA-repair replication was measured in wild-type, polA1, uvrD3, and polA1 uvrD3 strains of Escherichia coli K 12. A large stimulation of repair replication was observed in the uvrD3 strain, compared to the wild-type and polA1 strains. This enhanced repair replication was reduced in the polA1 uvrD3 strain. Therefore, a uvrD3 mutation appears to affect the amount of repair replication performed by DNA polymerase I. In the polA1 strain, there also appears to be an effect of the uvrD3 mutation on the amount of repair replication performed by DNA polymerase III (and/or II). The enhanced repair replication observed for the uvrD3 strains appears to be in response to the enhanced DNA degradation observed for these strains. (orig.)

  9. Is low-energy-ion bombardment generated X-ray emission a secondary mutational source to ion-beam-induced genetic mutation?

    Energy Technology Data Exchange (ETDEWEB)

    Thongkumkoon, P. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Prakrajang, K. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Thopan, P.; Yaopromsiri, C. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Suwannakachorn, D. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Yu, L.D., E-mail: yuld@fnrf.science.cmu.ac.th [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

    2013-07-15

    Highlights: ► Detected X-ray emission from metal, plastic and biological samples. ► Characteristic X-ray emission was detected from metal but not from non-metals. ► Low-energy ion bombarded bacteria held in different sample holders. ► Bacteria held in metal holder had higher mutation rate than in plastic holder. ► Ion-beam-induced X-ray from biological sample is not a basic mutation source. -- Abstract: Low-energy ion beam biotechnology has achieved tremendous successes in inducing crop mutation and gene transfer. However, mechanisms involved in the related processes are not yet well understood. In ion-beam-induced mutation, ion-bombardment-produced X-ray has been proposed to be one of the secondary mutation sources, but the speculation has not yet been experimentally tested. We carried out this investigation to test whether the low-energy ion-beam-produced X-ray was a source of ion-beam-induced mutation. In the investigation, X-ray emission from 29-keV nitrogen- or argon- ion beam bombarded bacterial Escherichia coli (E. coli) cells held in a metal or plastic sample holder was in situ detected using a highly sensitive X-ray detector. The ion beam bombarded bacterial cells held in different material holders were observed for mutation induction. The results led to a conclusion that secondary X-ray emitted from ion-beam-bombarded biological living materials themselves was not a, or at least a negligible, mutational source, but the ion-beam-induced X-ray emission from the metal that made the sample holder could be a source of mutation.

  10. Is low-energy-ion bombardment generated X-ray emission a secondary mutational source to ion-beam-induced genetic mutation?

    International Nuclear Information System (INIS)

    Thongkumkoon, P.; Prakrajang, K.; Thopan, P.; Yaopromsiri, C.; Suwannakachorn, D.; Yu, L.D.

    2013-01-01

    Highlights: ► Detected X-ray emission from metal, plastic and biological samples. ► Characteristic X-ray emission was detected from metal but not from non-metals. ► Low-energy ion bombarded bacteria held in different sample holders. ► Bacteria held in metal holder had higher mutation rate than in plastic holder. ► Ion-beam-induced X-ray from biological sample is not a basic mutation source. -- Abstract: Low-energy ion beam biotechnology has achieved tremendous successes in inducing crop mutation and gene transfer. However, mechanisms involved in the related processes are not yet well understood. In ion-beam-induced mutation, ion-bombardment-produced X-ray has been proposed to be one of the secondary mutation sources, but the speculation has not yet been experimentally tested. We carried out this investigation to test whether the low-energy ion-beam-produced X-ray was a source of ion-beam-induced mutation. In the investigation, X-ray emission from 29-keV nitrogen- or argon- ion beam bombarded bacterial Escherichia coli (E. coli) cells held in a metal or plastic sample holder was in situ detected using a highly sensitive X-ray detector. The ion beam bombarded bacterial cells held in different material holders were observed for mutation induction. The results led to a conclusion that secondary X-ray emitted from ion-beam-bombarded biological living materials themselves was not a, or at least a negligible, mutational source, but the ion-beam-induced X-ray emission from the metal that made the sample holder could be a source of mutation

  11. Radiation-induced cancer

    International Nuclear Information System (INIS)

    Dutrillaux, B.; CEA Fontenay-aux-Roses, 92

    1998-01-01

    The induction of malignant diseases is one of the most concerning late effects of ionising radiation. A large amount of information has been collected form atomic bomb survivors, patients after therapeutic irradiation, occupational follow-up and accidentally exposed populations. Major uncertainties persist in the (very) low range i.e, population and workers radioprotection. A review of the biological mechanisms leading to cancer strongly suggests that the vast majority of radiation-induced malignancies arise as a consequence of recessive mutations can be unveiled by ageing, this process being possibly furthered by constitutional or acquired genomic instability. The individual risk is likely to be very low, probably because of the usual dose level. However, the magnitude of medical exposure and the reliance of our societies on nuclear industry are so high that irreproachable decision-making processes and standards for practice are inescapable. (author)

  12. The spectrum of mutation produced by low dose radiation

    International Nuclear Information System (INIS)

    Morley, Alexander A.; Turner, David R.

    2004-01-01

    Inherited mutations are the basis of evolution and acquired mutations in humans are important in ageing, cancer and possibly various forms of tissue degeneration. Mutations are responsible for many of the long-term effects of radiation. However, sensitive direct detection of mutations in humans has been difficult. The aims of the project were to develop methods for the sensitive enumeration of mutations in DNA, to measure mutation frequencies in a wide variety of tissue types and to quantify the mutational effect of direct oxidative damage produced by radiation, at both high and low doses. The project was successful in developing a sensitive method which could detect mutations directly in the genetic material, DNA at a sensitivity of 1 mutated molecule in 1000000000 unmutated molecules. However a number of methodological problems had to be overcome and lack of ongoing funding made it impossible to fulfill all of the aims of the project

  13. Frequency and spectrum of chlorophyll-deficient mutations in rice after treatment with radiation and alkylating agents

    International Nuclear Information System (INIS)

    Bhan, A.K.; Kaul, M.L.H.

    1976-01-01

    Three varieties of rice were treated with gamma rays and two alkylating agents EMS and DES, separately and in combinations, with a view to finding out the frequency and spectrum of chlorophyll mutations in relation to the genotype and the nature of the mutagen. Chlorophyll mutation frequency was enhanced with increasing dose but dropped at very high doses (doses that induced over 90% seeding lethality in M 1 ). The fall was attributed to either the increased mutated sector and diplontic selection after exposure to very high doses or relatively high resistance of some of the seeds. Among chlorophyll mutants in M 2 induced by radiations as well as alkylating agents, the albina type formed the majority class. EMS induced a significantly higher proportion of albinas than did gamma rays

  14. Genetic improvement of 'NPq' rice with induced mutations

    International Nuclear Information System (INIS)

    Ram, Mahabal

    1974-01-01

    Exposure of the seeds of rice to different doses of gamma-rays increased the total mutation frequency with an increase in the dose rate, and the most economic mutations occurred around 30 kr. Induced mutants with dwarf plant type, early maturity, fine grain, high-yielding ability, and resistance to lodging and major diseases were isolated in the M, and M generations. Genetical studies indicated that height is controlled by 4 pairs of additive genes, grass-clumps by 2 pairs of non-allelic interacting genes (inhibitory), and chlorophyll mutations such as albina by 2 pairs of duplicate genes and xantha by a single gene pair. (author)

  15. Mutation induction in haploid yeast after split-dose radiation exposure. II. Combination of UV-irradiation and X-rays.

    Science.gov (United States)

    Keller, B; Zölzer, F; Kiefer, J

    2004-01-01

    Split-dose protocols can be used to investigate the kinetics of recovery from radiation damage and to elucidate the mechanisms of cell inactivation and mutation induction. In this study, a haploid strain of the yeast, Saccharomyces cerevisiae, wild-type with regard to radiation sensitivity, was irradiated with 254-nm ultraviolet (UV) light and then exposed to X-rays after incubation for 0-6 hr. The cells were incubated either on nutrient medium or salt agar between the treatments. Loss of reproductive ability and mutation to canavanine resistance were measured. When the X-ray exposure immediately followed UV-irradiation, the X-ray survival curves had the same slope irrespective of the pretreatment, while the X-ray mutation induction curves were changed from linear to linear quadratic with increasing UV fluence. Incubations up to about 3 hr on nutrient medium between the treatments led to synergism with respect to cell inactivation and antagonism with respect to mutation, but after 4-6 hr the two treatments acted independently. Incubation on salt agar did not cause any change in the survival curves, but there was a strong suppression of X-ray-induced mutation with increasing UV fluence. On the basis of these results, we suggest that mutation after combined UV and X-ray exposure is affected not only by the induction and suppression of DNA repair processes, but also by radiation-induced modifications of cell-cycle progression and changes in the expression of the mutant phenotype. Copyright 2004 Wiley-Liss, Inc.

  16. Recent advances in the estimation of genetic risks of exposure to ionizing radiation

    International Nuclear Information System (INIS)

    Sankaranarayanan, K.

    2002-01-01

    This paper reviews the major advances that have occurred during the last few years in the estimation of genetic risks of exposure of human populations to ionizing radiation. Among these are: (i) an upward revision of the estimates of the baseline frequencies of Mendelian diseases (from 1.25% to 2.4%); (ii) the conceptual change to the use of a doubling dose based on human data on spontaneous mutation rates and mouse data on induced mutation rates (from the one based entirely on mouse data on spontaneous and induced mutation rates, which was the case thus far); (iii) the fuller development of the concept of mutation component (MC) and its application to predict the responsiveness of Mendelian and chronic multi factorial diseases to induced mutations; (iv) the introduction of the concept that the major adverse effects of radiation exposure of human germ cells are likely to be manifest as multi-system developmental abnormalities and (v) the introduction of concept of potential recoverability correction factor (PRCF) to bridge the gap between induced mutations studied in mice and the risk of genetic disease in humans are reviewed

  17. Recovery during radiation mutagenesis

    International Nuclear Information System (INIS)

    Deen, D.F.; Shaw, E.I.

    1976-01-01

    Many variables (e.g. cell inoculum size, mutagen dose, expression time, and concentration of the selective agent) are known to affect the induced mutation frequency obtained in cultured mammalian cells. The authors have studied the effects of several parameters on the frequency of radiation-induced resistance to 8-azaguanine in asynchronous V79-171B hamster cells. Inoculation with 10 5 cells was followed by graded doses of radiation, expression times were optimized to maximize mutation frequency, and then the treated cells were challenged with 8-azaguanine for ten days. The optimal expression times which maximized mutation frequency were dose dependent and are in the range of 14-24, 24, and 24-36 hours respectively for doses of 250, 40 and 800 rads. A time interval of 24 hours between two 250-rad fractions resulted in a mutation frequency smaller than that obtained from administration of a single 500-rad dose. With 36 hours between halves of the dose, the induced mutation frequency was an order of magnitude lower than that produced by a single dose and actually below the unirradiated (spontaneous) frequency. Maintenance of cells after irradation first at 18 0 C for 24 hours, and then allowance of expression at 37 0 C for 24 hours, increased both the spontaneous and induced mutation frequency. A one-hour postirradiation balanced salt-solution treatment did not affect the number of spontaneous mutants that arose, but reduced the number of induced mutants. Thus, the balanced salt treatment lowers the induced mutation frequency about a factor of two. The possible significance of these results are discussed with respect to the role of radiation repair mechanisms during mutagenesis, and to recovery at low dose rates. A working hypothesis is advanced to explain the possible mechanism which causes expression time to vary as a function of the dose of mutagen. (author)

  18. Somatic mutation and recombination induced with reactor thermal neutrons in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Zambrano A, F.; Guzman R, J.; Paredes G, L.; Delfin L, A.

    1997-01-01

    The SMART test of Drosophila melanogaster was used to quantify the effect over the somatic mutation and recombination induced by thermal and fast neutrons at the TRIGA Mark III reactor of the ININ at the power of 300 k W for times of 30, 60 and 120 minutes with total equivalent doses respectively of 20.8, 41.6 and 83.2 Sv. A linear relation between the radiation equivalent dose and the frequency of the genetic effects such as mutation and recombination was observed. The obtained results allow to conclude that SMART is a sensitive system to the induced damage by neutrons, so this can be used for studying its biological effects. (Author)

  19. Radiation- induced aneuploidy in mammalian germ cells

    International Nuclear Information System (INIS)

    Tease, C.

    1989-01-01

    The ability of ionizing radiation to induce aneuploidy in mammalian germ cells has been investigated experimentally in the laboratory mouse using a variety of cytogenetic and genetic methods. These studies have provided unambiguous evidence of induced nondisjunction in both male and female germ cells when the effect of irradiation is screened in meiotic cells or preimplantation embryos. In contrast, however, cytogenetic analyses of post-implantation embryos and genetic assays for induced chromosome gains have not found a significant radiation effect. These apparently contradictory findings may be reconciled if (a) radiation induces tertiary rather than primary trisomy, or (b) induces embryo-lethal genetic damage, such as deletions, in addition to numerical anomalies. Either or both of these explanations may account for the apparent loss during gestation of radiation-induced trisomic embryos. Extrapolating from the information so far available, it seems unlikely that environmental exposure to low doses if low dose rate radiation will result in a detectable increase in the rate of aneuploidy in the human population. (author)

  20. Mutation Induction with UV- and X-radiations in spores and vegetative cells of Bacillus subtilis

    International Nuclear Information System (INIS)

    Tanooka, H.; Munakata, N.; Kitahara, S.

    1978-01-01

    Spores and vegetative cells of Bacillus subtilis strains with various defects in DNA-repair capacities (hcr - , ssp - , hcr - ssp - ) were irradiated with UV radiation or X-rays. Induced mutation frequency was determined from the observed frequency of prototrophic reversion of a suppressible auxotropic mutation. At equal physical dose, after either UV- or X-irradiation, spores were more resistant to mutations as well as to killing than were vegetative cells. However, quantitative comparison revealed that, at equally lethal doses, spores and vegetative cells were almost equally mutable by X-rays whereas spores were considerably less mutable by UV than were vegetative cells. Thus, as judged from their mutagenic efficiency relative to the lethality, X-ray-induced damage in the spore DNA and the vegetative DNA were equally mutagenic, while UV-induced DNA photoproducts in the spore were less mutagenic than those in vegetative cells. Post-treatment of UV-irradiated cells with caffeine decreased the survival and the induced mutation frequency for either spores or vegetative cells for all the strains. In X-irradiated spores however, a similar suppressing effect of caffeine was observed only for mutability of a strain lacking DNA polymerase I activity

  1. Sexual selection, germline mutation rate and sperm competition

    Directory of Open Access Journals (Sweden)

    Møller AP

    2003-04-01

    Full Text Available Abstract Background An important component of sexual selection arises because females obtain viability benefits for their offspring from their mate choice. Females choosing extra-pair fertilization generally favor males with exaggerated secondary sexual characters, and extra-pair paternity increases the variance in male reproductive success. Furthermore, females are assumed to benefit from 'good genes' from extra-pair sires. How additive genetic variance in such viability genes is maintained despite strong directional selection remains an evolutionary enigma. We propose that sexual selection is associated with elevated mutation rates, changing the balance between mutation and selection, thereby increasing variance in fitness and hence the benefits to be obtained from good genes sexual selection. Two hypotheses may account for such elevated mutation: (1 Increased sperm production associated with sperm competition may increase mutation rate. (2 Mutator alleles increase mutation rates that are revealed by the expression of condition-dependent secondary sexual characters used by choosy females during their mate choice. M Petrie has independently developed the idea that mutator alleles may account for the maintenance of genetic variation in viability despite strong directional selection. Results A comparative study of birds revealed a positive correlation between mutation rate at minisatellite loci and extra-pair paternity, but not between mutation rate and relative testes mass which is a measure of relative sperm production. Minisatellite mutation rates were not related to longevity, suggesting a meiotic rather than a mitotic origin of mutations. Conclusion We found evidence of increased mutation rate in species with more intense sexual selection. Increased mutation was not associated with increased sperm production, and we suggest that species with intense sexual selection may maintain elevated mutation rates because sexual selection continuously

  2. Induced mutation and in vitro culture techniques for the genetic improvement of ornamentals

    International Nuclear Information System (INIS)

    Lapade, Avelina G.; Veluz, Ana Maria S.; Marbella, Lucia J.; Rama, Manny G.

    2001-01-01

    Mutation breeding using cobalt-60 ( 60 Co) gamma radiation coupled with tissue culture techniques is undertaken for genetic improvement of foliage ornamentals (Dracaena sp. and Murraya exotica L.) and cutflowers (Chrysanthemum morifolium and orchids; Vanda sanderiana, Dendrobium Pattaya Beauty and Phalenopsis schilleriana). Gamma radiation (10-30 Gy) induced chlorophyll mutations and several morphological changes in D. sanderiana. For D. godseffiana, irradiated cuttings resulted in reduction of leaf size and chlorophyll mutations. Reduction in height was observed in the M 2 generation of Murraya exotica L. irradiated at doses ranging from 10 to 30 Gy. The dwarf Murraya mutant was multiplied through the use of seeds and presently 116 plants are commercially available and are ''test marketed'' to the public. Tissue culture technique was used to induce mutation and as a means of micropropagation in two ornamental crops (orchids and chrysanthemum). Effects of different doses of gamma radiation on callus induction from nodal sections of chrysanthemum grown in Murashige and Skoog's (MS) with naphthalene acetic acid (NAA) and benzyl adenine (BA) were studied. Micropropagation of irradiated and unirradiated chrysanthemum using MS basal medium is presently being studied. Whorling and changes in leaf color were observed at 10 Gy and doubling of leaf growth at the node at 20 Gy for vegetatively generated V 3 plant. In orchids, irradiation of immature embryo with gamma rays ranging from 5 to 10 Gy increased the percentage of germination in Dendrobium Pattaya Beauty and P. schilleriana. Protocorms of Vanda sanderiana irradiated at 10 Gy and grown in Knudson C medium developed into plantlets that are bigger and more vigorous than those irradiated at 20 GY and from the control plant. A decrease in seedling height was observed with increasing dose of gamma radiation. (Author)

  3. Radiation-induced adaptive response in human lymphoblast

    International Nuclear Information System (INIS)

    Yatagai, Fumio; Sugasawa, Kaoru

    2009-01-01

    Described are the genetic analysis of variant strains obtained by the optimal condition for radiation-induced adaptive response (AR), and molecular elucidation of the suppression of concomitant mutation. The TK6 cells (heterozygous thymidine kinase, +/-) were used for detection of mutation by loss of heterozygosity (LOH). The optimal conditions for reducing the mutation by subsequent irradiation (SI) to its rate of about 60% (vs control 100%, no PI) were found to be 5 cGy of pre-irradiation (PI) of X-ray and 2 Gy of SI with the interval of 6 hr, where mutated cells were of non-LOH type in around 25% and homo-LOH type by homologous recombination (HR) in 60%. By cDNA sequencing, the former cells having changed bases were found to be in variant strain ratio of 1/8 vs control 7/18, suggesting that the mutation was decreased mainly by suppression of base change. Expression of XPC protein, an important component for recognition of the base damage in global genome nucleotide excision repair, was studied by Western blotting as the possible mechanism of suppressing the mutation, which revealed different time dynamics of the protein in cells with PI+SI and SI alone (control). To see the effect of PI on the double strand break (DSB) repair, cells with PI were infected with restriction enzyme I-SceI vector to yield DSB instead of SI, which revealed more efficient repair (70% increase) by HR than control, without significant difference in non-homologous end-joining repair. Micro-array analysis to study the gene expression in the present experimental conditions for AR is in progress. The TK6 cells used here were thought useful for additional studies of the mechanism of AR as mutation by direct or indirect irradiation can be tested. (K.T.)

  4. Effect of hsm mutations enhancing spontaneous mutability on induced mutagenesis and mitotic recombination in Saccharomyces cerevisiae yeast

    International Nuclear Information System (INIS)

    Fedorova, I.V.; Koval'tsova, S.V.; Ivanov, E.L.

    1993-01-01

    The authors have studied the effect of five nonallelic hms1-hms5 mutations on the incidence of direct mutations in loci ADE1 and ADE2, induced by UV-radiation, 6-hydroxyl-aminopurine, and nitrosomethylurea. All hms mutants were found to be insensitive to the lethal action of these mutagens. The frequency of UV-induced mutations to adenine dependence was increased in mutants hsm2-1, hsm3-1, hsm5-1, and particularly in hsm1-1, but remained unchanged in hsm4-1 compared to HSM. Mutagenesis induced by 6-hydroxylaminopurine was increased in all mutants studied, particularly in mutant hsm3-1. The authors did not detect any appreciable effect of hsm mutations on mutagenesis induced by nitrosomethylurea. The frequency of spontaneous mitotic conversion to prototrophy was studied in diploids heteroallelic to gene ADE2 and homo- and heterozygous for hsm mutations. Mutation hsm5-1 considerably increased the frequency of conversion for all heteroalleles studied, mutations hsm1-1 and hsm3-1 also considerably increased the conversion frequency, while mutations hsm1-1 and hsm4-1 had little effect on this process. The study of the properties of hsm mutations revealed joint genetic control of spontaneous and induced mutagenesis and recombination in yeast. The possibility that hsm mutations belong to the class of mutations impairing correction of unpaired DNA bases is discussed. 25 refs., 3 figs., 3 tabs

  5. Molecular nature of mutations induced by high-LET irradiation with argon and carbon ions in Arabidopsis thaliana

    International Nuclear Information System (INIS)

    Hirano, Tomonari; Kazama, Yusuke; Ohbu, Sumie; Shirakawa, Yuki; Liu Yang; Kambara, Tadashi; Fukunishi, Nobuhisa; Abe, Tomoko

    2012-01-01

    Linear energy transfer (LET) is an important parameter to be considered in heavy-ion mutagenesis. However, in plants, no quantitative data are available on the molecular nature of the mutations induced with high-LET radiation above 101–124 keV μm −1 . In this study, we irradiated dry seeds of Arabidopsis thaliana with Ar and C ions with an LET of 290 keV μm −1 . We analyzed the DNA alterations caused by the higher-LET radiation. Mutants were identified from the M 2 pools. In total, 14 and 13 mutated genes, including bin2, egy1, gl1, gl2, hy1, hy3–5, ttg1, and var2, were identified in the plants derived from Ar- and C-ions irradiation, respectively. In the mutants from both irradiations, deletion was the most frequent type of mutation; 13 of the 14 mutated genes from the Ar ion-irradiated plants and 11 of the 13 mutated genes from the C ion-irradiated plants harbored deletions. Analysis of junction regions generated by the 2 types of irradiation suggested that alternative non-homologous end-joining was the predominant pathway of repair of break points. Among the deletions, the proportion of large deletions (>100 bp) was about 54% for Ar-ion irradiation and about 64% for C-ion irradiation. Both current results and previously reported data revealed that the proportions of the large deletions induced by 290-keV μm −1 radiations were higher than those of the large deletions induced by lower-LET radiations (6% for 22.5–30.0 keV μm −1 and 27% for 101–124 keV μm −1 ). Therefore, the 290 keV μm −1 heavy-ion beams can effectively induce large deletions and will prove useful as novel mutagens for plant breeding and analysis of gene functions, particularly tandemly arrayed genes.

  6. Molecular nature of mutations induced by high-LET irradiation with argon and carbon ions in Arabidopsis thaliana

    Energy Technology Data Exchange (ETDEWEB)

    Hirano, Tomonari; Kazama, Yusuke [Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Innovation Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Ohbu, Sumie; Shirakawa, Yuki; Liu Yang; Kambara, Tadashi; Fukunishi, Nobuhisa [Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Abe, Tomoko, E-mail: tomoabe@riken.jp [Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Innovation Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2012-07-01

    Linear energy transfer (LET) is an important parameter to be considered in heavy-ion mutagenesis. However, in plants, no quantitative data are available on the molecular nature of the mutations induced with high-LET radiation above 101-124 keV {mu}m{sup -1}. In this study, we irradiated dry seeds of Arabidopsis thaliana with Ar and C ions with an LET of 290 keV {mu}m{sup -1}. We analyzed the DNA alterations caused by the higher-LET radiation. Mutants were identified from the M{sub 2} pools. In total, 14 and 13 mutated genes, including bin2, egy1, gl1, gl2, hy1, hy3-5, ttg1, and var2, were identified in the plants derived from Ar- and C-ions irradiation, respectively. In the mutants from both irradiations, deletion was the most frequent type of mutation; 13 of the 14 mutated genes from the Ar ion-irradiated plants and 11 of the 13 mutated genes from the C ion-irradiated plants harbored deletions. Analysis of junction regions generated by the 2 types of irradiation suggested that alternative non-homologous end-joining was the predominant pathway of repair of break points. Among the deletions, the proportion of large deletions (>100 bp) was about 54% for Ar-ion irradiation and about 64% for C-ion irradiation. Both current results and previously reported data revealed that the proportions of the large deletions induced by 290-keV {mu}m{sup -1} radiations were higher than those of the large deletions induced by lower-LET radiations (6% for 22.5-30.0 keV {mu}m{sup -1} and 27% for 101-124 keV {mu}m{sup -1}). Therefore, the 290 keV {mu}m{sup -1} heavy-ion beams can effectively induce large deletions and will prove useful as novel mutagens for plant breeding and analysis of gene functions, particularly tandemly arrayed genes.

  7. Mitochondrial mutagenesis induced by tumor-specific radiation bystander effects.

    LENUS (Irish Health Repository)

    Gorman, Sheeona

    2012-02-01

    The radiation bystander effect is a cellular process whereby cells not directly exposed to radiation display cellular alterations similar to directly irradiated cells. Cellular targets including mitochondria have been postulated to play a significant role in this process. In this study, we utilized the Random Mutation Capture assay to quantify the levels of random mutations and deletions in the mitochondrial genome of bystander cells. A significant increase in the frequency of random mitochondrial mutations was found at 24 h in bystander cells exposed to conditioned media from irradiated tumor explants (p = 0.018). CG:TA mutations were the most abundant lesion induced. A transient increase in the frequency of random mitochondrial deletions was also detected in bystander cells exposed to conditioned media from tumor but not normal tissue at 24 h (p = 0.028). The increase in both point mutations and deletions was transient and not detected at 72 h. To further investigate mitochondrial dysfunction, mitochondrial membrane potential and reactive oxygen species were assessed in these bystander cells. There was a significant reduction in mitochondrial membrane potential and this was positively associated with the frequency of random point mutation and deletions in bystander cells treated with conditioned media from tumor tissue (r = 0.71, p = 0.02). This study has shown that mitochondrial genome alterations are an acute consequence of the radiation bystander effect secondary to mitochondrial dysfunction and suggests that this cannot be solely attributable to changes in ROS levels alone.

  8. Induced mutations in sesame breeding

    International Nuclear Information System (INIS)

    Ashri, A.

    2001-01-01

    The scope of induced mutations in sesame (Sesamum indicum L.) breeding is reviewed. So far in Egypt, India, Iraq, Rep. of Korea, and Sri Lanka, 14 officially released varieties have been developed through induced mutations: 12 directly and 2 through cross breeding (one using the 'dt45' induced mutant from Israel). For another variety released in China there are no details. The induced mutations approach was adopted primarily in order to obtain genetic variability that was not available in the germplasm collection. The mutagens commonly applied have been gamma rays, EMS and sodium azide. Sesame seeds can withstand high mutagen doses, and there are genotypic differences in sensitivity between varieties. The mutants induced in the above named countries and others include better yield, improved seed retention, determinate habit, modified plant architecture and size, more uniform and shorter maturation period, earliness, resistance to diseases, genic male sterility, seed coat color, higher oil content and modified fatty acids composition. Some of the induced mutants have already given rise to improved varieties, the breeding value of other mutants is now being assessed and still others can serve as useful markers in genetic studies and breeding programmes. (author)

  9. Induced mutation of Dendrobium orchid

    International Nuclear Information System (INIS)

    Sakinah Ariffin; Mohd Nazir Basiran

    2000-01-01

    Dendrobiiim orchids serve as the main orchid cut flower export of Malaysia. The wide range of colour and forms presently available in the market are obtained through hybridisation. Induced mutation breeding program was initiated on a commercial variety Dendrobium 'Sonia Kai' to explore the possibilities of obtaining new colour and forms. Matured seeds from self pollination were cultured and irradiated at 35 Gy at the protocorm-like bodies (PLBS) stage. Selection of induced mutations was done after the first flowering of the plants regenerated from the irradiated protocorms. Results showed changes in flower colour, shape and size. Most of these chances are expressed in different combinations in the petals, sepals and lip of the flowers. Thus, resulting. in a very wide spectrum of mutations. Some of these chances are not stable. To date, mutants that showed stable characteristics changes are grouped into 11 categories based on flower colour and form. These results show that the combination of its vitro technique and induced mutation can be applied in orchid breeding to produce new interesting and attractive variety for the market

  10. Problems and solutions in the estimation of genetic risks from radiation and chemicals

    International Nuclear Information System (INIS)

    Russell, W.L.

    1980-01-01

    Extensive investigations with mice on the effects of various physical and biological factors, such as dose rate, sex and cell stage, on radiation-induced mutation have provided an evaluation of the genetics hazards of radiation in man. The mutational results obtained in both sexes with progressive lowering of the radiation dose rate have permitted estimation of the mutation frequency expected under the low-level radiation conditions of most human exposure. Supplementing the studies on mutation frequency are investigations on the phenotypic effects of mutations in mice, particularly anatomical disorders of the skeleton, which allow an estimation of the degree of human handicap associated with the occurrence of parallel defects in man. Estimation of the genetic risk from chemical mutagens is much more difficult, and the research is much less advanced. Results on transmitted mutations in mice indicate a poor correlation with mutation induction in non-mammalian organisms

  11. Avoiding dangerous missense: thermophiles display especially low mutation rates.

    Directory of Open Access Journals (Sweden)

    John W Drake

    2009-06-01

    Full Text Available Rates of spontaneous mutation have been estimated under optimal growth conditions for a variety of DNA-based microbes, including viruses, bacteria, and eukaryotes. When expressed as genomic mutation rates, most of the values were in the vicinity of 0.003-0.004 with a range of less than two-fold. Because the genome sizes varied by roughly 10(4-fold, the mutation rates per average base pair varied inversely by a similar factor. Even though the commonality of the observed genomic rates remains unexplained, it implies that mutation rates in unstressed microbes reach values that can be finely tuned by evolution. An insight originating in the 1920s and maturing in the 1960s proposed that the genomic mutation rate would reflect a balance between the deleterious effect of the average mutation and the cost of further reducing the mutation rate. If this view is correct, then increasing the deleterious impact of the average mutation should be countered by reducing the genomic mutation rate. It is a common observation that many neutral or nearly neutral mutations become strongly deleterious at higher temperatures, in which case they are called temperature-sensitive mutations. Recently, the kinds and rates of spontaneous mutations were described for two microbial thermophiles, a bacterium and an archaeon. Using an updated method to extrapolate from mutation-reporter genes to whole genomes reveals that the rate of base substitutions is substantially lower in these two thermophiles than in mesophiles. This result provides the first experimental support for the concept of an evolved balance between the total genomic impact of mutations and the cost of further reducing the basal mutation rate.

  12. The estimation of risks from the induction of recessive mutations after exposure to ionising radiation

    International Nuclear Information System (INIS)

    Searle, A.G.; Edwards, J.H.

    1986-01-01

    Induced recessive mutations can cause harm by (1) partnership with a defective allele already established in the population; (2) partnership with another recessive mutation induced at the same locus; (3) the formation of homozygous descendants, that is, identify by descent; and (4) heterozygous effects. Calculations based on a combination of data from observations on human populations and from mouse experiments suggest that an extra genetically significant dose of 1 cGy X or γ irradiation received by each parent in a stable population with a million liveborn offspring would induce up to 1200 extra recessive mutations. From partnership effects, about one extra case of recessive disease would be expected in the following 10 generations. Homozygosity resulting from identity by descent could not normally occur until the fourth generation after exposure but, on certain assumptions, about ten extra cases of recessive disease would be expected from this cause by the tenth generation. In the same period, about 250 recessive alleles would be eliminated in heterozygotes given 2.5% heterozygous disadvantage. These deleterious heterozygous effects should not be combined with those of dominants, as has been done in some previous risk estimates. It is considered unlikely that many radiation induced recessives would show heterozygous advantage. Certain dominants should be excluded from calculations of mutational risk because they are unlikely to be maintained by mutation. (author)

  13. Mutations induced by the action of metal ions in Pisum

    Energy Technology Data Exchange (ETDEWEB)

    von Rosen, G

    1957-01-01

    Simple metal ions may induce both radiomimetic effects and genuine gene mutations of the same type which occurs from ionizing radiation and from treatment with some chemical agencies as e.g., mustard gas. The main material during the experiments has been species of Pisum. The biochemical principle which lies behind these reactions is the complex-forming ability among those reactive bivalent metal elements. The author assumes that interruptions of the chelate formation in the cell synthesis form the real background to the observed activity of the metal ions. The possible role in the evolution of the plant- and animal kingdom and the probable value for plant-breeding of the mutation activity observed are suggested. A new field for mutation experiments may here be opened and the results must hitherto be judged as interesting and promising. 13 references, 7 figures, 4 tables.

  14. Induction and identification of somatic mutations with particular reference to perennial plants. Part of a coordinated programme on improvement of vegetatively propagated crops and tree crops through radiation-induced mutations

    International Nuclear Information System (INIS)

    Zubrzycki, H.M.

    1980-06-01

    An attempt was made to obtain resistance of oranges (Citrus sinensis L. Osbeck) and grapefruit (C. paradisi Macf.) to Tristeza virus by induced mutation breeding. Two methods were used. In one, buds were treated with X or gamma radiation. The detached sprouts were subsequently grafted. In the other, a number of chemical mutagens were used: diethyl sulfate or propylenoxide on buds; diethyl sulfate or nitrosemethylurethane on seeds (2400). The selection and isolation of mutants from treated buds and seeds, respectively, are described. Intermediate results only are given and discussed

  15. A mutant of a mutant of a mutant of a ...: Irradiation of progressive radiation-induced mutants in a mutation-breeding programme with Chrysanthenum morifolium RAM

    International Nuclear Information System (INIS)

    Broertjes, C.; Koene, P.; Veen, J.W.H. van.

    1980-01-01

    Radiation-induced sports in Chrysanthemum morifolium RAM. have been reported for several years. It has become an everyday practice to produce flower-colour mutants from outstanding cross-breeding products, even before they are distributed for the commercial production of cut flowers. One of the most successful and recent examples is that of cv. Horim, of which hundreds of mutants were produced by successive use of radiation-induced mutants in the mutation-breeding programme. Over about 4 years a variety of flower-colour mutants was obtained, not only largely including the outstanding characteristics of the original cultivar but sometimes even with an appreciable improvement in quality and yield. It is expected that the latter types, the Miros group, will soon completely supersede the spontaneous or raditation-induced Horim sports and mutants and take over the leading position of the Horim group in the production of all-year-round (AYR) cut-flowers. (orig.)

  16. The effects of radiation dose-rate and quality on the induction of dominant lethals in mouse spermatids

    International Nuclear Information System (INIS)

    Searle, A.G.; Beechey, G.V.

    1981-01-01

    Hybrid male mice were given 3 Gy (300 rad) doses of X- or γ-irradiation at dose-rates of either 0.6 or 0.002 Gy/min for each radiation. Germ-cells treated as spermatids were tested for dominant lethality. Effects on spermatogonia were evaluated by studying testis-weight, sperm-count and sperm abnormalities. The rate of induction of dominant lethal mutations was 2.1 times as high after acute X-irradiation as after protracted γ-irradiation. Most of this difference resulted from the change in radiation quality, since the relative effectiveness of X- versus γ-irradiation was 1.9 at low and 1.6 at high dose rates. For each radiation, however, fewer dominant lethals were induced at low dose-rates than at high (low/high ratios of 0.8 and 0.9 respectively) although differences did not reach a significant level. There were no statistically significant effects of dose rate on testis-weight of sperm-count in the X-ray series, but there were significantly less severe effects on both with protraction of the γ-irradiation. Evidence for effects of radiation quality on these characters was conflicting. Frequencies of abnormal spermatozoa were markedly increased 7 weeks after irradiation but there were no consistent effects of radiation intensity or quality. (orig.)

  17. Molecular nature of forvard gene mutations induced by γ- and UV-irradiation ip the yeast Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Ivanov, E.L.; Koval'tsova, S.V.; Korolev, V.G.

    1983-01-01

    Gamma and UV-radiation induce the following mutation spectra in the ADE2 gene of Saccharomyces cerevisial yeast respectively: 27 and 41% of GTs→AT transitions, 8 and 11% of AT→GTs transitions, 59 and 40% transversions, 6 and 8% mutations of the reading fame shift type. The results obtained prove the presence of specific nature of UV rays in respect to induction of GTs→AT transitions. The experimental data are discussed from the point of view of studying molecular mechanisms of radiation mutagenesis

  18. Molecular analysis of two mouse dilute locus deletion mutations: Spontaneous dilute lethal20J and radiation-induced dilute prenatal lethal Aa2 alleles

    International Nuclear Information System (INIS)

    Strobel, M.C.; Seperack, P.K.; Copeland, N.G.; Jenkins, N.A.

    1990-01-01

    The dilute (d) coat color locus of mouse chromosome 9 has been identified by more than 200 spontaneous and mutagen-induced recessive mutations. With the advent of molecular probes for this locus, the molecular lesion associated with different dilute alleles can be recognized and precisely defined. In this study, two dilute mutations, dilute-lethal20J (dl20J) and dilute prenatal lethal Aa2, have been examined. Using a dilute locus genomic probe in Southern blot analysis, we detected unique restriction fragments in dl20J and Aa2 DNA. Subsequent analysis of these fragments showed that they represented deletion breakpoint fusion fragments. DNA sequence analysis of each mutation-associated deletion breakpoint fusion fragment suggests that both genomic deletions were generated by nonhomologous recombination events. The spontaneous dl20J mutation is caused by an interstitial deletion that removes a single coding exon of the dilute gene. The correlation between this discrete deletion and the expression of all dilute-associated phenotypes in dl20J homozygotes defines the dl20J mutation as a functional null allele of the dilute gene. The radiation-induced Aa2 allele is a multilocus deletion that, by complementation analysis, affects both the dilute locus and the proximal prenatal lethal-3 (pl-3) functional unit. Molecular analysis of the Aa2 deletion breakpoint fusion fragment has provided access to a previously undefined gene proximal to d. Initial characterization of this new gene suggests that it may represent the genetically defined pl-3 functional unit

  19. Mutation Breeding Newsletter. No. 39

    International Nuclear Information System (INIS)

    1992-01-01

    This newsletter contains brief articles on the use of radiation to induce mutations in plants; radiation-induced mutants in Chrysanthemum; disrupting the association between oil and protein content in soybean seeds; mutation studies on bougainvillea; a new pepper cultivar; and the use of mutation induction to improve the quality of yam beans. A short review of the seminar on the use of mutation and related biotechnology for crop improvement in the Middle East and Mediterranean regions, and a description of a Co-ordinated Research Programme on the application of DNA-based marker mutations for the improvement of cereals and other sexually reproduced crop species are also included. Two tables are given: these are based on the ''FAO/IAEA Mutant Varieties Database'' and show the number of mutated varieties and the number of officially released mutant varieties in particular crops/species. Refs and tabs

  20. Radiation induced genetic damage in Aspergillus nidulans

    International Nuclear Information System (INIS)

    Georgiou, J.T.

    1984-01-01

    The mechanism by which ionizing radiation induces genetic damage in haploid and diploid conidia of Aspergillus nidulans was investigated. Although the linear dose-response curves obtained following low LET irradiation implied a 'single-hit' action of radiation, high LET radiations were much more efficient than low LET radiations, which suggests the involvement of a multiple target system. It was found that the RBE values for non-disjunction and mitotic crossing-over were very different. Unlike mitotic crossing-over, the RBE values for non-disjunction were much greater than for cell killing. This suggests that non-disjunction is a particularly sensitive genetical endpoint that is brought about by damage to a small, probably non-DNA target. Radiosensitisers were used to study whether radiation acts at the level of the DNA or some other cellular component. The sensitisation to electrons and/or X-rays by oxygen, and two nitroimidazoles (metronidazole and misonidazole) was examined for radiation induced non-disjunction, mitotic crossing-over, gene conversion, point mutation and cell killing. It was found that these compounds sensitised the cells considerably more to genetic damage than to cell killing. (author)

  1. Mutational specificity of γ-rays

    International Nuclear Information System (INIS)

    Hoebee, Barbara.

    1990-01-01

    The aim of the study described in this thesis was to get more information on the mutagenic properties of radiation-induced DNA modifications and the possible mechanisms involved in radiation-induced mutagenesis, principally by investigating the kinds of mutations by DNA sequence analysis. The mutations were analyzed after γ-irradiation of recombinant bacteriophage M13 and plasmide pUC DNA in diluted aqueous solutions, followed by transfection or transformation to E. coli cells, in which the damaged DNA molecules are repaired and replicated. Error-prone repair, misrepair or bypass of lesions during replication may lead to the introduction of mutations. Both the M13 and the plasmid DNA used in our mutation studies contain a mutation target sequence, which makes an easy selection and sequence analysis of mutant DNA molecules possible. Under the radiation conditions used, e.g. irradiation of diluted aqueous DNA solutions, only DNA damage occurs introduced by the water derived OH* and H* radicals and the hydrated electrons. By using different gas conditions during irradiation the relative yields of these reaction species can be manipulated, which opens up the opportunity to determine their effects separately. The mutation spectrum obtained in double-stranded (ds) M13DNA after irradiation under oxic conditions and the mutation spectrum obtained under the same conditions and in the same mutation target but cloned in plasmid DNA, are described. The mutation specificity under anoxic conditions in ds M13DNA is given. Results obtained after irradiation of ds M13DNA under N 2 conditions are discussed together with experiments with single-stranded DNA. Similarities and differences between radiation-induced mutation spectra obtained by other groups and those presented in this thesis are discussed. (author). 155 refs.; 134 figs.; 16 tabs

  2. Inflammation, gene mutation and photoimmunosuppression in response to UVR-induced oxidative damage contributes to photocarcinogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Halliday, Gary M. [Dermatology Research Laboratories, Division of Medicine, Melanoma and Skin Cancer Research Institute, Royal Prince Alfred Hospital at the University of Sydney, Sydney, NSW (Australia)]. E-mail: garyh@med.usyd.edu.au

    2005-04-01

    Ultraviolet (UV) radiation causes inflammation, gene mutation and immunosuppression in the skin. These biological changes are responsible for photocarcinogenesis. UV radiation in sunlight is divided into two wavebands, UVB and UVA, both of which contribute to these biological changes, and therefore probably to skin cancer in humans and animal models. Oxidative damage caused by UV contributes to inflammation, gene mutation and immunosuppression. This article reviews evidence for the hypothesis that UV oxidative damage to these processes contributes to photocarcinogenesis. UVA makes a larger impact on oxidative stress in the skin than UVB by inducing reactive oxygen and nitrogen species which damage DNA, protein and lipids and which also lead to NAD+ depletion, and therefore energy loss from the cell. Lipid peroxidation induces prostaglandin production that in association with UV-induced nitric oxide production causes inflammation. Inflammation drives benign human solar keratosis (SK) to undergo malignant conversion into squamous cell carcinoma (SCC) probably because the inflammatory cells produce reactive oxygen species, thus increasing oxidative damage to DNA and the immune system. Reactive oxygen or nitrogen appears to cause the increase in mutational burden as SK progress into SCC in humans. UVA is particularly important in causing immunosuppression in both humans and mice, and UV lipid peroxidation induced prostaglandin production and UV activation of nitric oxide synthase is important mediators of this event. Other immunosuppressive events are likely to be initiated by UV oxidative stress. Antioxidants have also been shown to reduce photocarcinogenesis. While most of this evidence comes from studies in mice, there is supporting evidence in humans that UV-induced oxidative damage contributes to inflammation, gene mutation and immunosuppression. Available evidence implicates oxidative damage as an important contributor to sunlight-induced carcinogenesis in humans.

  3. Inflammation, gene mutation and photoimmunosuppression in response to UVR-induced oxidative damage contributes to photocarcinogenesis

    International Nuclear Information System (INIS)

    Halliday, Gary M.

    2005-01-01

    Ultraviolet (UV) radiation causes inflammation, gene mutation and immunosuppression in the skin. These biological changes are responsible for photocarcinogenesis. UV radiation in sunlight is divided into two wavebands, UVB and UVA, both of which contribute to these biological changes, and therefore probably to skin cancer in humans and animal models. Oxidative damage caused by UV contributes to inflammation, gene mutation and immunosuppression. This article reviews evidence for the hypothesis that UV oxidative damage to these processes contributes to photocarcinogenesis. UVA makes a larger impact on oxidative stress in the skin than UVB by inducing reactive oxygen and nitrogen species which damage DNA, protein and lipids and which also lead to NAD+ depletion, and therefore energy loss from the cell. Lipid peroxidation induces prostaglandin production that in association with UV-induced nitric oxide production causes inflammation. Inflammation drives benign human solar keratosis (SK) to undergo malignant conversion into squamous cell carcinoma (SCC) probably because the inflammatory cells produce reactive oxygen species, thus increasing oxidative damage to DNA and the immune system. Reactive oxygen or nitrogen appears to cause the increase in mutational burden as SK progress into SCC in humans. UVA is particularly important in causing immunosuppression in both humans and mice, and UV lipid peroxidation induced prostaglandin production and UV activation of nitric oxide synthase is important mediators of this event. Other immunosuppressive events are likely to be initiated by UV oxidative stress. Antioxidants have also been shown to reduce photocarcinogenesis. While most of this evidence comes from studies in mice, there is supporting evidence in humans that UV-induced oxidative damage contributes to inflammation, gene mutation and immunosuppression. Available evidence implicates oxidative damage as an important contributor to sunlight-induced carcinogenesis in humans

  4. Intercellular distribution of mutations induced in oopcytes of Drosophila melanogaster by chemical and physical mutagens

    International Nuclear Information System (INIS)

    Traut, H.

    1979-01-01

    When females of Drosophila melanogaster are treated with chemical or physical mutagens, not only in one but also in both of the two homologous X chromosomes of a given oocyte, a recessive sex-linked lethal mutation may be induced. A method is described that discriminates between such single and double mutations. A theory is developed to show how a comparison betweeen the expected and the observer frequency of double mutations yields an indication of the intercellular distribution (random or nonrandom) of recessive lethal mutations induced by mutagenic agents in oocytes and, consequently, of the distribution (homogenous or nonhomogeneous) of those agents. Three agents were tested: FUdR (12.5, 50.0 and 81.0 μg/ml), mitomycin C (130.0 μg/ml) and x rays (2000 R, 150 kV). After FUdR feeding, no increase in the mutation frequency usually observed in D. melanogaster without mutagenic treatment was obtained (u = 0.13%, namely three single mutations among 2332 chromosomes tested). After mitomycin C feeding 104 single and three double mutations were obtained. All of the 50 mutations observed after x irradiation were single mutations. The results obtained in the mitomycin C and radiation experiments favor the assumption of a random intercellular distribution of recessive lethal mutations induced by these two agents in oocytes of D. melanogaster. Reasons are discussed why for other types of mutagenic agents nonrandom distributions may be observed with our technique

  5. Hyperthermia-induced alteration of yeast susceptibility to mutation

    International Nuclear Information System (INIS)

    Mitchel, R.E.J.; Morrison, D.P.

    1985-01-01

    Diploid yeast (s. cerevisiae) were examined for alterations in susceptibility to induced mutation following hyperthermia treatment. In cells grown at 23 0 C, a non-lethal heat exposure (38 0 C, 30 min) markedly suppressed mutation induced by a subsequent non-killing dose of MNNG of MNU. Mutation by ENU, 8-MOP + UVA, or γ-rays was not affected. An intermediate level of mutation suppression was observed for mutation by 254nm UV or MMS. Mutation by MNNG was not suppressed by the same heat treatment delivered after the mutagen exposure. In a split dose experiment (two MNNG treatments separated by a heat exposure) no suppression of mutation was observed. Treatment with cycloheximide mimicked the effect of heat treatment. These data suggest that mutation induction by MNNG or MNU is protein synthesis dependent, i.e. an error-prone repair system is induced by exposure to MNNG or MNU but not by ENU, 8-MOP+UVA or γ-irradiation. We propose that hyperthermia treatment, by inducing stress protein synthesis at the expense of normal protein synthesis, precludes induction of this error-prone system. Therefore, in heat treated cells, DNA lesions produced by MNNG or MNU exposure must be resolved by an essentially constitutive system which is less error-prone than the inducible one

  6. Dose rate effect on the yield of radiation induced response with thermal fading

    International Nuclear Information System (INIS)

    Chernov, V.; Rogalev, B.; Barboza-Flores, M.

    2005-01-01

    A model describing the dependences of the accumulation of thermally unstable radiation induced defects on the dose and dose rate is proposed. The model directly takes into account the track nature of the ionizing radiation represented as accumulation processes of defects in tracks averaged over a crystal volume considering various degrees of overlapping in space and time. The accumulation of the defects in the tracks is phenomenologically described. General expressions are obtained that allows radiation yield simulation of defects involving known creation and transformation processes. The cases considered, of linear accumulation (constant increment of the defects in tracks) and accumulation with saturation (complete saturation of the defects in one track), lead to a set of linear dose dependences with saturation, which are routinely used in luminescence and ESR dating. The accumulation, with increase of sensitivity in regions overlapped by two or more tracks, gave a set of dose dependences, from linear-sublinear-linear-saturation, distinctive of quartz up to linear-supralinear-linear-saturation. It is shown that the effect of the dose rate on dose dependences is determined by a dimensionless parameter a=Pτ/D0, where P is the dose rate, τ is the defect lifetime and D0 is the track dose. At a-bar 1 the dose rate influences basically the accumulation of thermally unstable defects. In the reverse case the dose dependences did not seems to be influenced by the dose rate

  7. Nature of mutants induced by ionizing radiation in cultured hamster cells. II. Antigenic response and reverse mutation of HPRT-deficient mutants induced by. gamma. -rays or ethyl methanesulphonate

    Energy Technology Data Exchange (ETDEWEB)

    Brown, R; Stretch, A; Thacker, J

    1986-04-01

    A large series of independent mutants deficient in HPRT enzyme activity, isolated from V79-4 hamster cells, were assessed for properties which reflect the nature of the genetic changes induced. A total of 88 mutants were screened, 43 isolated from ..gamma..-ray-treated cultures and 45 induced by ethyl methanesulphonate (EMS). Firstly, each mutant was assayed for the presence of protein with the antigenic response of HPRT. In a competitive inhibition assay, 31% of EMS-induced mutants were CRM-positive compared to 7% of the ..gamma..-ray series. Secondly, each mutant was tested for ability to revert to HPRT proficiency. All except 2 of the EMS-induced mutants reverted with ethyl nitrosourea ENU, and many reverted spontaneously, under the given conditions. However reversion was not detected in about 80% of ..gamma..-ray-induced mutants, suggesting that the types of forward mutation caused by ionizing radiation differ qualitatively from those caused by EMS. (Auth.). 30 refs.; 6 figs.; 2 tabs.

  8. Mutations in the FHA-domain of ectopically expressed NBS1 lead to radiosensitization and to no increase in somatic mutation rates via a partial suppression of homologous recombination

    International Nuclear Information System (INIS)

    Ohara, Maki; Funyu, Yumi; Ebara, Shunsuke

    2014-01-01

    Ionizing radiation induces DNA double-strand breaks (DSBs). Mammalian cells repair DSBs through multiple pathways, and the repair pathway that is utilized may affect cellular radiation sensitivity. In this study, we examined effects on cellular radiosensitivity resulting from functional alterations in homologous recombination (HR). HR was inhibited by overexpression of the forkhead-associated (FHA) domain-mutated NBS1 (G27D/R28D: FHA-2D) protein in HeLa cells or in hamster cells carrying a human X-chromosome. Cells expressing FHA-2D presented partially (but significantly) HR-deficient phenotypes, which were assayed by the reduction of gene conversion frequencies measured with a reporter assay, a decrease in radiation-induced Mre11 foci formation, and hypersensitivity to camptothecin treatments. Interestingly, ectopic expression of FHA-2D did not increase the frequency of radiation-induced somatic mutations at the HPRT locus, suggesting that a partial reduction of HR efficiency has only a slight effect on genomic stability. The expression of FHA-2D rendered the exponentially growing cell population slightly (but significantly) more sensitive to ionizing radiation. This radiosensitization effect due to the expression of FHA-2D was enhanced when the cells were irradiated with split doses delivered at 24-h intervals. Furthermore, enhancement of radiation sensitivity by split dose irradiation was not seen in contact-inhibited G0/G1 populations, even though the cells expressed FHA-2D. These results suggest that the FHA domain of NBS1 might be an effective molecular target that can be used to induce radiosensitization using low molecular weight chemicals, and that partial inhibition of HR might improve the effectiveness of cancer radiotherapy. (author)

  9. Current status and outlook perspectives of induced mutations for plant improvement

    International Nuclear Information System (INIS)

    Liu Luxiang; Guo Huijun; Zhao Linshu; Li Junhui; Gu Jiayu; ZZhao Shirong; Wang Jing

    2009-01-01

    Since 1928, induced mutations have played a significant role in solving world food and nutritional security problems through mutant germplasm enhancement and new mutant variety development. According to incomplete statistics, up to September 2009, induced mutations have officially released 3088 mutant cultivars in more than 170 crop species by more than 60 countries in the world. China tanks the first in the world, which has have released 802 mutant cultivars in 45 crop species, and takes more than a quarter of the total number of mutant varieties in the FAO/IAEA database. The maximum annually accumulated planting area of the mutant varieties was 9 million hectares, with an additional increase of 1.5 billion kilograms to national output of grain, cotton, oil, being converted to social and economic benefits of more than 2 billion RMB. The recent development and application of accelerator ion beam irradiation, the spaceflight environment and the other new mutation means, as well as the effective use of traditional radiation mutagenesis are becoming more active in crop improvement and new gene discovery. The advent of plant genomics and high throughput DNA techniques, such as TILLING, have opened a new era of molecular mutation breeding, which will overcome the limitations of conventional mutation breeding and play a significant role in solving China and world food security. (authors)

  10. Improved amylose content of rice (IR72) induced through gamma radiation

    International Nuclear Information System (INIS)

    Barrida, Adelaida C.; Rivera, Faye G.; Manrique, Mary Jayne C.; Dimaano, Arvin O.; Costimiano, Eduardo C.

    2015-01-01

    In general grain quality and quality preferences vary across rice growing countries and regions. Filipinos preferres translucent, well milled, long grain rice with aroma and minimal broken grains which is soft after cooling. The amylose content of rice starch is a major eating quality factor. The aim of this study is to develop rice mutants with good eating quality and low to intermediate amylose content through induced mutation using gamma radiation. Low to intermediate amylose content in rice were identified and selected among the advance generation lines irradiated with 200 and 300Gy dose of gamma radiation. Screening was done using qualitative method (Iodine staining method). Selected lines were analyzed quantitatively, to determine the percent amylose content. Percent amylose were group to several categories where; 0-6% is waxy, 6-12% is very low, 12-18% is low, 18-24% is intermediate and >25% is high. Results were further confirmed using molecular marker technique by looking at the waxy gene which code for granule bound starch synthase I (GBSSI) and controls amylose content in rice. Among the 30 lines selcted and anaylzes, 2 lines were confirmed to have a gene base mutation with a low to intermediate amylose content. Thus, induced mutation using gamma radiation has successfully improved amylose content in rice (IR72). (author)

  11. Evaluating and validating the protocol for gamma radiation induced mutations in floral distinct rosa spp

    International Nuclear Information System (INIS)

    Qadeer, M.; Hafiz, I. A.; Abbasi, N. A.; Ahmad, T.

    2015-01-01

    Among the highly fragrant Rosa species, Rosa gruss an teplitz and Rosa centifolia have high value in terms of commercial importance and economical trade. However, the absence of floral diversification and diversity in color patterns in these species acts as limiting factors in floriculture trade of these species. In the present study, we aimed to induce mutations using gamma radiations up to 120 Gy to observe the rate and the correlated effects on the several plant traits in micropropagated shoot tips of Rosa gruss an teplitz and Rosa centifolia. Irradiated shoot tips were micropropagated for one culture cycle and were acclimatized in a green house after in vitro rooting. Plants of irradiated population at 60 and 30 Gy showed 78.12 and 38.50 percentage less culture rooting percentage age as well as 23.82 and 7 percentage less flower size as compared to non irradiated population of Rosa gruss an teplitz and Rosa centifolia respectively. Moreover, flower color component a* (+ redness - green, 36.16 and 27.16) and chroma (37.77 and 27.5) depicted minimum while L* (Lightness, 45.12 and 76.64), b* (+ yellow - blue, 10.69 and -4.14) and hue angle (17.1 and -8.58) maximum value. Apart from these variations, mutants of Rosa gruss an teplitz also produced variegated, pink color and different shape flowers. Genetic variations observed among the putative mutants of Rosa gruss an teplitz and Rosa centifolia were evaluated using twelve decamer RAPD primers. Phylogenetic inferences showed large genetic diversity in putative mutants as compared to mother plant. (author)

  12. Tunnel effect in excited and ionized states of nucleic acid bases and some aspects of radiation-induced point gene mutations

    International Nuclear Information System (INIS)

    Pleticha-Lansky, R.

    1975-01-01

    Radiation induced perturbations of the genetic code are discussed from the standpoint of the frequency and specificity of mutations. According to Lowdin's theory of tautomeric rearrangement of nucleic acid base pairs through the tunnel effect, it is probable, that the proton potential in hydrogen bridges can be also effected by the incorporation of some radiolytic products of purines and pyrimidines into DNA as mistake bases. In this way it is possible, to eliminate any exo-or endogeneous energetic irradiation of the biological material and so to eliminate various undesirable damages of DNA. Thus higher specificity in the controlling of the genetic code changes would result. (F.G.)

  13. Heavy ion induced mutation in arabidopsis

    Energy Technology Data Exchange (ETDEWEB)

    Tano, Shigemitsu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1997-03-01

    Heavy ions, He, C, Ar and Ne were irradiated to the seeds of Arabidopsis thaliana for inducing the new mutants. In the irradiated generation (M{sub 1}), germination and survival rate were observed to estimate the relative biological effectiveness in relation to the LET including the inactivation cross section. Mutation frequencies were compared by using three kinds of genetic loci after irradiation with C ions and electrons. Several interesting new mutants were selected in the selfed progenies of heavy ion irradiated seeds. (author)

  14. Cytogenetic effects of ionizing radiation in peripheral lymphocytes of ISS crew members

    Science.gov (United States)

    Johannes, Christian; Goedecke, Wolfgang; Antonopoulos, Alexandra; Obe, Günter; Horstmann, Markus

    High energy radiation is a major risk factor in manned space missions. Astronauts and cosmonauts are exposed to ionising radiations of cosmic and solar origin, while on the Earth's surface people are well protected by the atmosphere and a deflecting magnetic field. There are now data available describing the dose and the quality of ionising radiation on-board of the International Space Station (ISS). The effect of the increased radiation dose on mutation rates of ISS crew members are hard to predict. Therefore, direct measurements of mutation rates are required.The analysis of chromosomal aberrations in peripheral blood lymphocytes is a well established method to measure radiation-induced mutations. We present data of chromosome aberration analyses from lymphocyte metaphase spreads of ISS crew members participating in short term (10-14 days) or long term (6 months) missions. From each subject we received two blood samples. The first sample was drawn about 10 days before launch and a second sample was drawn within 3 days after return from their flights. From lymphocyte cultures metaphase plates were prepared on glass slides. Metaphases were Giemsa stained or hybridised using multicolour FISH probes. All types of chromosome changes were scored in pre-flight and post-flight blood samples and the mutation rates were compared. Results obtained in chromosomal studies on long-term flight crew members showed pronounced inter-individual differences in the response to cosmic radiation exposure. Overall significant elevations of typical radiation induced aberrations, i.e., dicentric chromosomes and reciprocal translocations have been observed in long-term crew members. Our data indicate no elevation of mutation rates due to short-term stays on-board the ISS.

  15. Mutation induction in a mouse lymphoma cell mutant sensitive to 4-nitroquinoline 1-oxide and ultraviolet radiation

    International Nuclear Information System (INIS)

    Sato, K.; Hieda, N.

    1980-01-01

    The mutant mouse lymphoma cell Q31, which is sensitive to 4-nitroquinoline 1-oxide and ultraviolet radiation (UV), was compared with the parental L5178Y cell for the effect of caffeine and mutation induction after UV irradiation. Caffeine potentiated the lethal effect of UV in both cell strains to a similar extent, indicating that the defective process in Q31 cells was caffeine-insensitive. UV-induced mutation to 6-thioguanine resistance was determined in L5178Y and Q31 cells. The maximal yield of mutants was obtained 7 days post-irradiation in L5178Y cells and 14 days in Q31 cells for higher UV doses. It appears that a much longer time is required for the mutant cells than for the parental cells for full expression of the resistance phenotype even at equitoxic UV doses. A substantially higher frequency in induced mutations was observed in Q31 cells than in L5178Y cells at a given dose of UV. A plot of induced mutation frequency as a function of logarithm of surviving fraction again indicates hypermutability of Q31 cells as compared with the parental strain. In contrast, X-rays induced a similar frequency of mutations to 6-thioguanine resistance in L5178Y and Q31 cells. (orig.)

  16. Mutation breeding newsletter. No. 33

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1989-01-01

    This issue of the newsletter reports a number of research news and research abstracts on application of radiation induced mutation techniques to increase mutagenesis and mutation frequency in plant breeding projects.

  17. Mutation breeding newsletter. No. 33

    International Nuclear Information System (INIS)

    1989-01-01

    This issue of the newsletter reports a number of research news and research abstracts on application of radiation induced mutation techniques to increase mutagenesis and mutation frequency in plant breeding projects

  18. Radiation-induced base substitution mutagenesis in single-stranded DNA phage M13

    International Nuclear Information System (INIS)

    Brandenburger, A.; Godson, G.N.; Glickman, B.W.; Sluis, C.A. van

    1981-01-01

    To elucidate the relative contributions of targeted and untargeted mutations to γ and UV radiation mutagenesis, the DNA sequences of 174 M13 revertant phages isolated from stocks of irradiated or unirradiated amber mutants grown in irradiated (SOS-induced) or unirradiated (non-induced) host bacteria, have been determined. Differences in the spectra of base change mutations induced in the various conditions were apparent, but no obvious specificity of mutagenesis was detected. In particular, under the present conditions, pyrimidine dimers did not seem to be the principal sites of UV-induced base substitution mutagenesis, suggesting that such mutagenesis occurs at the sites of lesions other than pyrimidine dimers, or is untargeted. (U.K.)

  19. Review of low dose-rate epidemiological studies and biological mechanisms of dose-rate effects on radiation induced carcinogenesis

    International Nuclear Information System (INIS)

    Iwasaki, Toshiyasu; Otsuka, Kensuke; Yoshida, Kazuo

    2015-01-01

    Radiation protection system adopts the linear non-threshold model with using dose and dose-rate effectiveness factor (DDREF). The dose-rate range where DDREF is applied is below 100 mGy per hour, and it is regarded that there are no dose-rate effects at very low dose rate, less than of the order of 10 mGy per year, even from the biological risk evaluation model based on cellular and molecular level mechanisms for maintenance of genetic integrity. Among low dose-rate epidemiological studies, studies of residents in high natural background areas showed no increase of cancer risks at less than about 10 mGy per year. On the other hand, some studies include a study of the Techa River cohort suggested the increase of cancer risks to the similar degree of Atomic bomb survivor data. The difference of those results was supposed due to the difference of dose rate. In 2014, International Commission on Radiological Protection opened a draft report on stem cell biology for public consultations. The report proposed a hypothesis based on the new idea of stem cell competition as a tissue level quality control mechanism, and suggested that it could explain the dose-rate effects around a few milligray per year. To verify this hypothesis, it would be needed to clarify the existence and the lowest dose of radiation-induced stem cell competition, and to elucidate the rate of stem cell turnover and radiation effects on it. As for the turnover, replenishment of damaged stem cells would be the important biological process. It would be meaningful to collect the information to show the difference of dose rates where the competition and the replenishment would be the predominant processes. (author)

  20. Induced Mutations for Improving Production on Bread and Durum Wheat

    Science.gov (United States)

    Stamo, Ilirjana; Ylli, Ariana; Dodbiba, Andon

    2007-04-01

    Wheat is a very important crop and has been bred for food and its improvement is continuous from cross-breeding. Radiation and chemically induced mutations have provided variability in selection for novel varieties. Four bread and one durum wheat cultivars were exposed to gamma rays, Cs 137 with doses 10, 15 and 20 krad (2000 seeds of each dose and cultivars). We have isolated mutant plants with height reduced and on cv Progress spike without chaff.

  1. Induced Mutations for Improving Production on Bread and Durum Wheat

    International Nuclear Information System (INIS)

    Stamo, Ilirjana; Ylli, Ariana; Dodbiba, Andon

    2007-01-01

    Wheat is a very important crop and has been bred for food and its improvement is continuous from cross-breeding. Radiation and chemically induced mutations have provided variability in selection for novel varieties. Four bread and one durum wheat cultivars were exposed to gamma rays, Cs 137 with doses 10, 15 and 20 krad (2000 seeds of each dose and cultivars). We have isolated mutant plants with height reduced and on cv Progress spike without chaff

  2. The effect of a change in mutation rate on the incidence of dominant and X-linked recessive disorders in man

    International Nuclear Information System (INIS)

    Childs, J.D.

    1981-01-01

    In order to assess the impact on man of a sustained change in mutation rate that might be caused by ionizing radiation or a chemical mutagen in the environment, it is important to determine the current incidence of genetic disease, the rate at which deleterious mutations arise and the number of generations that mutations persist before eliminated by selection. From these data it should be possible to estimate both the increase in genetic disease in the first generation following the increase in mutation rate, and the rate at which a new equilibrium between mutation and selection would occur. In this paper the results of a survey to determine birth frequency, mutation rate and reproductive fitness for each of the important dominant and X-linked recessive disorders are described. It is estimated that these disorders affect about 0.6% of live-born individuals, including 0.1% of live-borns who carry a newly-arising mutation. (orig.)

  3. Gamma-ray induced mutation breeding in tree fruit crops

    International Nuclear Information System (INIS)

    Ito, Yuji

    1998-01-01

    In many vegetatively propagated crops and tree fruit crops, spontaneous mutations have played an important role in the development of cultivars. Thus, induced mutation breeding has been thought to be a promising way to improve commercially important cultivars. At the Institute of Radiation Breeding (IRB), studies on induced mutation breeding of temperate zone fruit trees using gamma-rays have been performed since 1962. Black spot disease, caused by Alternaria alternata Japanese pear pathotype, is one of the most serious diseases of Japanese pear (Pyrus pyrifolia NAKAI var. culta NAKAI) in Japan. It is known that some Japanese pear cultivars are completely resistant to the disease. The pathogenic fungi produces host-specific toxins (named AK-toxin) (Tanaka 1993, Otani et al. 1973). The susceptibility of Japanese pear is controlled by a single dominant gene (Kozaki 1973). To improve the Japanese pear cultivar 'Nijisseiki', which is highly susceptible to black spot disease, young grafted plants of 'Nijisseiki' have been irradiated chronically in the Gamma Field of the IRB since 1962. In 1981, one twig of a tree planted at a distance of 53 m from the 60 Co source with an exposure rate of 0.138 Gy/day (20hr-irradiation) was selected as the first resistant mutant. It was designated as cultivar 'Gold Nijisseiki' and released in 1990. A selection method for mutants resistant to black spot disease using the pathogen produced toxin and pear leaf disks was established. It is a simple and stable selection method. Up to the present, three mutant cultivars resistant to black spot disease have been bred at the IRB by chronic and acute gamma-ray irradiation. They showed intermediate resistance compared with the completely resitan cultivar 'Choujuurou' and highly susceptible cultivar 'Nijisseiki'. We obtained some apple mutants resistant to alternaria leaf blotch disease using toxin and leaf disks and are also attempting to obtain mutant resistant to some disease in other temperate

  4. High mutation rates limit evolutionary adaptation in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Kathleen Sprouffske

    2018-04-01

    Full Text Available Mutation is fundamental to evolution, because it generates the genetic variation on which selection can act. In nature, genetic changes often increase the mutation rate in systems that range from viruses and bacteria to human tumors. Such an increase promotes the accumulation of frequent deleterious or neutral alleles, but it can also increase the chances that a population acquires rare beneficial alleles. Here, we study how up to 100-fold increases in Escherichia coli's genomic mutation rate affect adaptive evolution. To do so, we evolved multiple replicate populations of asexual E. coli strains engineered to have four different mutation rates for 3000 generations in the laboratory. We measured the ability of evolved populations to grow in their original environment and in more than 90 novel chemical environments. In addition, we subjected the populations to whole genome population sequencing. Although populations with higher mutation rates accumulated greater genetic diversity, this diversity conveyed benefits only for modestly increased mutation rates, where populations adapted faster and also thrived better than their ancestors in some novel environments. In contrast, some populations at the highest mutation rates showed reduced adaptation during evolution, and failed to thrive in all of the 90 alternative environments. In addition, they experienced a dramatic decrease in mutation rate. Our work demonstrates that the mutation rate changes the global balance between deleterious and beneficial mutational effects on fitness. In contrast to most theoretical models, our experiments suggest that this tipping point already occurs at the modest mutation rates that are found in the wild.

  5. High mutation rates limit evolutionary adaptation in Escherichia coli

    Science.gov (United States)

    Wagner, Andreas

    2018-01-01

    Mutation is fundamental to evolution, because it generates the genetic variation on which selection can act. In nature, genetic changes often increase the mutation rate in systems that range from viruses and bacteria to human tumors. Such an increase promotes the accumulation of frequent deleterious or neutral alleles, but it can also increase the chances that a population acquires rare beneficial alleles. Here, we study how up to 100-fold increases in Escherichia coli’s genomic mutation rate affect adaptive evolution. To do so, we evolved multiple replicate populations of asexual E. coli strains engineered to have four different mutation rates for 3000 generations in the laboratory. We measured the ability of evolved populations to grow in their original environment and in more than 90 novel chemical environments. In addition, we subjected the populations to whole genome population sequencing. Although populations with higher mutation rates accumulated greater genetic diversity, this diversity conveyed benefits only for modestly increased mutation rates, where populations adapted faster and also thrived better than their ancestors in some novel environments. In contrast, some populations at the highest mutation rates showed reduced adaptation during evolution, and failed to thrive in all of the 90 alternative environments. In addition, they experienced a dramatic decrease in mutation rate. Our work demonstrates that the mutation rate changes the global balance between deleterious and beneficial mutational effects on fitness. In contrast to most theoretical models, our experiments suggest that this tipping point already occurs at the modest mutation rates that are found in the wild. PMID:29702649

  6. Contribution of radiation-induced, nitric oxide-mediated bystander effect to radiation-induced adaptive response.

    Science.gov (United States)

    Matsumoto, H.; Ohnishi, T.

    There has been a recent upsurge of interest in radiation-induced adaptive response and bystander effect which are specific modes in stress response to low-dose low-dose rate radiation Recently we found that the accumulation of inducible nitric oxide NO synthase iNOS in wt p53 cells was induced by chronic irradiation with gamma rays followed by acute irradiation with X-rays but not by each one resulting in an increase in nitrite concentrations of medium It is suggested that the accumulation of iNOS may be due to the depression of acute irradiation-induced p53 functions by pre-chronic irradiation In addition we found that the radiosensitivity of wt p53 cells against acute irradiation with X-rays was reduced after chronic irradiation with gamma rays This reduction of radiosensitivity of wt p53 cells was nearly completely suppressed by the addition of NO scavenger carboxy-PTIO to the medium This reduction of radiosensitivity of wt p53 cells is just radiation-induced adaptive response suggesting that NO-mediated bystander effect may considerably contribute to adaptive response induced by radiation

  7. Minisatellite germline mutation rate in the Techa River population

    Energy Technology Data Exchange (ETDEWEB)

    Dubrova, Yuri E. [Department of Genetics, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)]. E-mail: yed2@le.ac.uk; Ploshchanskaya, Olga G. [Urals Research Centre for Radiation Medicine, Medgorodok, Chelyabinsk 454076 (Russian Federation); Department of Radiobiology, Chelyabinsk State University, Chelyabinsk 454021 (Russian Federation); Kozionova, Olga S. [Urals Research Centre for Radiation Medicine, Medgorodok, Chelyabinsk 454076 (Russian Federation); Department of Radiobiology, Chelyabinsk State University, Chelyabinsk 454021 (Russian Federation); Akleyev, Alexander V. [Urals Research Centre for Radiation Medicine, Medgorodok, Chelyabinsk 454076 (Russian Federation); Department of Radiobiology, Chelyabinsk State University, Chelyabinsk 454021 (Russian Federation)

    2006-12-01

    Germline mutation at eight minisatellite loci has been studied among the irradiated families from the Techa River population and non-exposed families from the rural area of the Chelyabinsk and Kurgan Oblasts. The groups were matched by ethnicity, parental age, occupation and smoking habit. A statistically significant 1.7-fold increase in mutation rate was found in the germline of irradiated fathers, whereas maternal germline mutation rate in the exposed families was not elevated. Most of the minisatellite loci showed an elevated paternal mutation rate in the exposed group, indicating a generalised increase in minisatellite germline mutation rate in the Techa River population. These data suggest that the elevated minisatellite mutation rate can be attributed to radioactive exposure. The spectra of paternal mutation seen in the unexposed and exposed families were indistinguishable.

  8. Minisatellite germline mutation rate in the Techa River population

    International Nuclear Information System (INIS)

    Dubrova, Yuri E.; Ploshchanskaya, Olga G.; Kozionova, Olga S.; Akleyev, Alexander V.

    2006-01-01

    Germline mutation at eight minisatellite loci has been studied among the irradiated families from the Techa River population and non-exposed families from the rural area of the Chelyabinsk and Kurgan Oblasts. The groups were matched by ethnicity, parental age, occupation and smoking habit. A statistically significant 1.7-fold increase in mutation rate was found in the germline of irradiated fathers, whereas maternal germline mutation rate in the exposed families was not elevated. Most of the minisatellite loci showed an elevated paternal mutation rate in the exposed group, indicating a generalised increase in minisatellite germline mutation rate in the Techa River population. These data suggest that the elevated minisatellite mutation rate can be attributed to radioactive exposure. The spectra of paternal mutation seen in the unexposed and exposed families were indistinguishable

  9. Precise estimates of mutation rate and spectrum in yeast

    Science.gov (United States)

    Zhu, Yuan O.; Siegal, Mark L.; Hall, David W.; Petrov, Dmitri A.

    2014-01-01

    Mutation is the ultimate source of genetic variation. The most direct and unbiased method of studying spontaneous mutations is via mutation accumulation (MA) lines. Until recently, MA experiments were limited by the cost of sequencing and thus provided us with small numbers of mutational events and therefore imprecise estimates of rates and patterns of mutation. We used whole-genome sequencing to identify nearly 1,000 spontaneous mutation events accumulated over ∼311,000 generations in 145 diploid MA lines of the budding yeast Saccharomyces cerevisiae. MA experiments are usually assumed to have negligible levels of selection, but even mild selection will remove strongly deleterious events. We take advantage of such patterns of selection and show that mutation classes such as indels and aneuploidies (especially monosomies) are proportionately much more likely to contribute mutations of large effect. We also provide conservative estimates of indel, aneuploidy, environment-dependent dominant lethal, and recessive lethal mutation rates. To our knowledge, for the first time in yeast MA data, we identified a sufficiently large number of single-nucleotide mutations to measure context-dependent mutation rates and were able to (i) confirm strong AT bias of mutation in yeast driven by high rate of mutations from C/G to T/A and (ii) detect a higher rate of mutation at C/G nucleotides in two specific contexts consistent with cytosine methylation in S. cerevisiae. PMID:24847077

  10. Experimental evolution and the dynamics of genomic mutation rate modifiers.

    Science.gov (United States)

    Raynes, Y; Sniegowski, P D

    2014-11-01

    Because genes that affect mutation rates are themselves subject to mutation, mutation rates can be influenced by natural selection and other evolutionary forces. The population genetics of mutation rate modifier alleles has been a subject of theoretical interest for many decades. Here, we review experimental contributions to our understanding of mutation rate modifier dynamics. Numerous evolution experiments have shown that mutator alleles (modifiers that elevate the genomic mutation rate) can readily rise to high frequencies via genetic hitchhiking in non-recombining microbial populations. Whereas these results certainly provide an explanatory framework for observations of sporadically high mutation rates in pathogenic microbes and in cancer lineages, it is nonetheless true that most natural populations have very low mutation rates. This raises the interesting question of how mutator hitchhiking is suppressed or its phenotypic effect reversed in natural populations. Very little experimental work has addressed this question; with this in mind, we identify some promising areas for future experimental investigation.

  11. Monitoring mutations in people: an in vivo study of people accidentally or occupationally exposed to ionizing radiation

    International Nuclear Information System (INIS)

    Glickman, B.W.

    1996-01-01

    Recent developments in molecular biology and medicine now permit the monitoring of mutation in humans 'in vivo'. The most commonly used approach, and the main one reported in this paper, is the study of mutations at the hypoxanthine phosphoribosyl transferase (hprt) locus in peripheral T-lymphocytes. This paper deals with evidence from the radiological accident in Goiania, Brazil (where several hundred people were accidentally exposed to cesium-137), from a study of Soviet cosmonauts, and from monozygotic twins. The conclusions from Brazil are: mutation at hprt increases with age and is higher in smokers; in adults a linear dose response was found; no radiation-induced mutational fingerprint was found; children are particularly sensitive; the level of mutation dropped over several years (probably reflecting natural T-cell turnover). The conclusions from cosmonauts are: each cosmonaut had a significantly above-average level of mutation, but this may not be due to radiation at all; no 'fingerprint' was found, and there was no apparent dependence on dose. The study of twins showed a very strong correlation of mutant frequencies between one twin and the other, but this correlation decreased with age, presumably due to environmental effects. 1 tab., 2 figs

  12. The (1+λ) evolutionary algorithm with self-adjusting mutation rate

    DEFF Research Database (Denmark)

    Doerr, Benjamin; Witt, Carsten; Gießen, Christian

    2017-01-01

    We propose a new way to self-adjust the mutation rate in population-based evolutionary algorithms. Roughly speaking, it consists of creating half the offspring with a mutation rate that is twice the current mutation rate and the other half with half the current rate. The mutation rate is then upd......We propose a new way to self-adjust the mutation rate in population-based evolutionary algorithms. Roughly speaking, it consists of creating half the offspring with a mutation rate that is twice the current mutation rate and the other half with half the current rate. The mutation rate...... is then updated to the rate used in that subpopulation which contains the best offspring. We analyze how the (1 + A) evolutionary algorithm with this self-adjusting mutation rate optimizes the OneMax test function. We prove that this dynamic version of the (1 + A) EA finds the optimum in an expected optimization...... time (number of fitness evaluations) of O(nA/log A + n log n). This time is asymptotically smaller than the optimization time of the classic (1 + A) EA. Previous work shows that this performance is best-possible among all A-parallel mutation-based unbiased black-box algorithms. This result shows...

  13. High LET radiation enhances apoptosis in mutated p53 cancer cells through Caspase-9 activation

    International Nuclear Information System (INIS)

    Yamakawa, Nobuhiro; Takahashi, Akihisa; Mori, Eiichiro; Imai, Yuichiro; Ohnishi, Ken; Kirita, Tadaaki; Ohnishi, Takeo; Furusawa, Yoshiya

    2008-01-01

    Although mutations in the p53 gene can lead to resistance to radiotherapy, chemotherapy and thermotherapy, high linear energy transfer (LET) radiation induces apoptosis regardless of p53 gene status in cancer cells. The aim of this study was to clarify the mechanisms involved in high LET radiation-induced apoptosis. Human gingival cancer cells (Ca9-22 cells) containing a mutated p53 (mp53) gene were irradiated with X-rays, C-ion (13-100 KeV/μm), or Fe-ion beams (200 KeV/μm). Cellular sensitivities were determined using colony forming assays. Apoptosis was detected and quantified with Hoechst 33342 staining. The activity of Caspase-3 was analyzed with Western blotting and flow cytometry. Cells irradiated with high LET radiation showed a high sensitivity with a high frequency of apoptosis induction. The relative biological effectiveness (RBE) values for the surviving fraction and apoptosis induction increased in a LET-dependent manner. Both RBE curves reached a peak at 100 KeV/μm, and then decreased at values over 100 KeV/μm. When cells were irradiated with high LET radiation, Caspase-3 was cleaved and activated, leading to poly (ADP-ribose) polymerase (PARP) cleavage. In addition, Caspase-9 inhibitor suppressed Caspase-3 activation and apoptosis induction resulting from high LET radiation to a greater extent than Caspase-8 inhibitor. These results suggest that high LET radiation enhances apoptosis by activation of Caspase-3 through Caspase-9, even in the presence of mp53. (author)

  14. Modifying effect of 5-fluoro-2-deoxiuridine on the frequency of x-ray-induced visible mutations in wheat

    International Nuclear Information System (INIS)

    Azatyan, R.A.; Avakyan, V.A.

    1985-01-01

    A modifying effect of FUDR on the output of visible mutations induced by X-ray radiation has been studied at soft fall wheat (Tr. aestivum var. turcicum). It is shown that at X-ray radiation of dry seeds with subsequent treatment of FUDR increased is the mutant percent in M 3 which has constituted 0.61% at irradiation in dose of 100 Gy ad 1.03% at irradiation by the same dose and FUDR influence during 10 hours. In analogous variants at irradiation by 150 Gi dose the mutation frequency reached 1.47 and 2.07% respectively. It is shown that FUDR postradiation treatment promotes not only the increase of frequency but consderablly widens the spectrum of induced mutations. A supposition is made that FUDR modyfying effect is caused by DNA synthesis inhibition. A problem is discussed on a possible realization of potential DNA changes caused by irradiation, at additional influence of inhibitor

  15. Complicated biallelic inactivation of Pten in radiation-induced mouse thymic lymphomas

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Yu [Department of Biology, Graduate School of Science, Chiba University, Yayoicho, Inage-ku, Chiba 263-8522 (Japan); Experimental Radiobiology for Children' s Health Research Group, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555 (Japan); Takabatake, Takashi; Kakinuma, Shizuko; Amasaki, Yoshiko; Nishimura, Mayumi; Imaoka, Tatsuhiko; Yamauchi, Kazumi; Shang, Yi [Experimental Radiobiology for Children' s Health Research Group, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555 (Japan); Miyoshi-Imamura, Tomoko [Experimental Radiobiology for Children' s Health Research Group, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555 (Japan); Genetic Counseling Program, Graduate School of Humanities and Sciences, Ochanomizu University, 2-1-1 Otsuka, Bunkyou-ku, Tokyo 112-8610 (Japan); Nogawa, Hiroyuki [Department of Biology, Graduate School of Science, Chiba University, Yayoicho, Inage-ku, Chiba 263-8522 (Japan); Kobayashi, Yoshiro [Department of Biomolecular Science, Faculty of Science, Toho University, Miyama 2-2-1, Funabashi, Chiba 274-8510 (Japan); Shimada, Yoshiya, E-mail: y_shimad@nirsgo.jp [Experimental Radiobiology for Children' s Health Research Group, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555 (Japan)

    2010-04-01

    Inactivation of the phosphatase and tensin homolog gene (Pten) occurs via multiple tissue-dependent mechanisms including epigenetic silencing, point mutations, insertions, and deletions. Although frequent loss of heterozygosity around the Pten locus and plausible involvement of epigenetic silencing have been reported in radiation-induced thymic lymphomas, the proportion of lymphomas with inactivated Pten and the spectrum of causal aberrations have not been extensively characterized. Here, we assessed the mode of Pten inactivation by comprehensive analysis of the expression and alteration of Pten in 23 radiation-induced thymic lymphomas developed in B6C3F1 mice. We found no evidence for methylation-associated silencing of Pten; rather, complex structural abnormalities comprised of missense and nonsense mutations, 1- and 3-bp insertions, and focal deletions were identified in 8 of 23 lymphomas (35%). Sequencing of deletion breakpoints suggested that aberrant V(D)J recombination and microhomology-mediated rearrangement were responsible for the focal deletions. Seven of the 8 lymphomas had biallelic alterations, and 4 of them did not express Pten protein. These Pten aberrations coincided with downstream Akt phosphorylation. In conclusion, we demonstrate that Pten inactivation is frequently biallelic and is caused by a variety of structural abnormalities (rather than by epigenetic silencing) and is involved in radiation-induced lymphomagenesis.

  16. Induced mutation for accelerated domestication: a case study of winged bean (Psophocarpus tetragonolobus (L.) (DC)

    International Nuclear Information System (INIS)

    Klu, G. Y. P.

    2000-01-01

    Induced mutations have the ability to increase the rate of domestication of the many under exploited species of plants that may be potentially useful as source of food, forage and industrial raw materials. The process of domestication has been conditioned by single or major gene mutations. The role of mutagenesis in speeding up domestication, which is species dependent, is outlined in this paper. A case study of the role of induced mutations in the domestication of winged bean (Psophocarpus tetragonobolus) is also presented (au)

  17. Mutation and cancer in relation to the atomic-bomb radiation effects

    International Nuclear Information System (INIS)

    Kondo, Sohei

    1988-01-01

    Epidemiologic studies have provided many clues useful for elucidating mechanisms of induction of cancer and mutation in man after exposure to radiation. In the present paper, these clues are considered together with recent developments in the knowledge of carcinogenesis and mutagenesis in Drosophila, mice, rats and cultured human cells. A working hypothesis is presented for radiation carcinogenesis in man. The descriptions are given under two sections: I) Genetic and oncogenic effects of the A-bomb radiations, and II) Experimental mutagenesis and carcinogenesis relevant to the A-bomb radiation effects. Using data on somatic deletion and recombination in hemopoietic stem cells of A-bomb survivors, the two-mutation model is converted into a numerical equation for the frequency of the production of a preleukemic cell as a function of radiation dose. The slope of the theoretical dose-response curve obtained from this equation agrees faily well with those of the actual dose-response of leukemia in A-bomb survivors in Hiroshima and Nagasaki except at a low dose. Experimental evidence supports the model that radiation acts, at high doses above a threshold value, as a promotor to produce cancer. Obviously, the promotor model predicts a sigmoidal dose-response. In fact, 4 out of 5 types of cancer in Nagasaki show seemingly sigmoidal curves; the mortality rate is lower among the group exposed in a limited low dose range than among the unexposed group. Whether such a low-level radiation really exerts beneficial effects is open for future study. (N.K.) 68 refs

  18. Neutron-induced mutation experiments and total radiation-induced genetic damage in entire genomes of Drosophila melanogaster. Final report, November 1, 1967-August 31, 1980

    International Nuclear Information System (INIS)

    Abrahamson, S.

    1981-02-01

    Neutron-induced mutation experiments with Drosophila oogonia were conducted at the University of Wisconsin, with irradiations being carried out at the RARAF facility at Brookhaven National Laboratory. X-linked recessive lethals and specific locus mutations were studied. Using the α value of the weighted linear regression equation for lethal data, RBE's relative to X-rays were calculated for the energies of neutrons studied. They are: 15 MeV to 2.0; 6 MeV to 2.9; 2 MeV to 3.2; .66 MeV to 4.0; .43 MeV to 4.8. The dose/frequency response curves for lethal data of all neutron energies studied was suggestive of a quadratic component. All data best fit a linear hypothesis, however. Control data for specific locus mutations was used to estimate the number of loci on the X-chromosome which are capable of mutating to lethals. Neutron-induced data for specific locus mutation was inconclusive due to the high error inherent in the frequencies obtained

  19. Mutation induction in plants by ionizing radiation

    International Nuclear Information System (INIS)

    1985-01-01

    This training film deals with the use of x-rays, gamma rays and fast neutrons for mutation induction in plants. Specific features of different types of ionizing radiation and of biological materials are outlined and methods demonstrated which control modifying factors and warrant an efficient physical mutagenesis. The first step of mutation breeding aims at an enhanced level of genetic variation which forms the basis for mutant selection and use in plant breeding

  20. A mathematical model for leukemogenesis of radiation-induced acute myeloid leukemia in C3H/He mice

    International Nuclear Information System (INIS)

    Kai, M.; Ban, N.

    2002-01-01

    We developed a mathematical model in leukemogenesis of acute myeloid leukemia(AML) in C3H/He mice irradiated. Our previous study indicated that the leukemogenesis of AML was associated with a deletion of chromosome 2 directly induced by acute radiation. We hypothesized that radiation-induced AML needs both inactivation of one allele of a causative gene directly induced by acute radiation and another mutational event at the other allele. We analyzed data using a two-stage stochastic model for carcinogenesis. Model fitting was based on the maximum likelihood method. Our model analysis suggested that a single exposure might induce the long-lasting delayed cell death of radiation-induced initiated cells, and that the incidence of AML may be determined through both radiation-induced initiation and persistent increase of delayed cell death of the initiated cell induced by radiation

  1. Mutation breeding newsletter. No. 45

    International Nuclear Information System (INIS)

    2001-07-01

    This issue of the Mutation Breeding newsletter contains 39 articles dealing with radiation induced mutations and chemical mutagenesis techniques in plant breeding programs with the aims of improving crop productivity and disease resistance as well as exploring genetic variabilities

  2. A Constant Rate of Spontaneous Mutation in DNA-Based Microbes

    Science.gov (United States)

    Drake, John W.

    1991-08-01

    In terms of evolution and fitness, the most significant spontaneous mutation rate is likely to be that for the entire genome (or its nonfrivolous fraction). Information is now available to calculate this rate for several DNA-based haploid microbes, including bacteriophages with single- or double-stranded DNA, a bacterium, a yeast, and a filamentous fungus. Their genome sizes vary by ≈6500-fold. Their average mutation rates per base pair vary by ≈16,000-fold, whereas their mutation rates per genome vary by only ≈2.5-fold, apparently randomly, around a mean value of 0.0033 per DNA replication. The average mutation rate per base pair is inversely proportional to genome size. Therefore, a nearly invariant microbial mutation rate appears to have evolved. Because this rate is uniform in such diverse organisms, it is likely to be determined by deep general forces, perhaps by a balance between the usually deleterious effects of mutation and the physiological costs of further reducing mutation rates.

  3. Methylglyoxal-bis(guanylhydrazone), a polyamine analogue, sensitized γ-radiation-induced cell death in HL-60 leukemia cells Sensitizing effect of MGBG on γ-radiation-induced cell death.

    Science.gov (United States)

    Kim, Jin Sik; Lee, Jin; Chung, Hai Won; Choi, Han; Paik, Sang Gi; Kim, In Gyu

    2006-09-01

    Methylglyoxal-bis(guanylhydrazone) (MGBG), a polyamine analogue, has been known to inhibit the biosynthesis of polyamines, which are important in cell proliferation. We showed that MGBG treatment significantly affected γ-radiation-induced cell cycle transition (G(1)/G(0)→S→G(2)/M) and thus γ-radiation-induced cell death. As determined by micronuclei and comet assay, we showed that it sensitized the cytotoxic effect induced by γ-radiation. One of the reasons is that polyamine depletion by MGBG treatment did not effectively protect against the chemical (OH) or physical damage to DNA caused by γ-radiation. Through in vitro experiment, we confirmed that DNA strand breaks induced by γ-radiation was prevented more effectively in the presence of polyamines (spermine and spermidine) than in the absence of polyamines. MGBG also blocks the cell cycle transition caused by γ-radiation (G(2) arrest), which helps protect cells by allowing time for DNA repair before entry into mitosis or apoptosis, via the down regulation of cyclin D1, which mediates the transition from G(1) to S phase of cell cycle, and ataxia telangiectasia mutated, which is involved in the DNA sensing, repair and cell cycle check point. Therefore, the abrogation of G(2) arrest sensitizes cells to the effect of γ-radiation. As a result, γ-radiation-induced cell death increased by about 2.5-3.0-fold in cells treated with MGBG. However, exogenous spermidine supplement partially relieved this γ-radiation-induced cytotoxicity and cell death. These findings suggest a potentially therapeutic strategy for increasing the cytotoxic efficacy of γ-radiation.

  4. Research highlights on: the use of induced mutations for plant improvement in Malaysia

    International Nuclear Information System (INIS)

    1998-01-01

    Nuclear techniques play an increasingly valuable role in agricultural research and development. The collaborative work of IAEA and FAO has been instrumental to the progress. The nuclear techniques are now used in a wide range of applications including crop improvement. In the initial years, many plant breeders had difficulty in believing that induced mutations through radiation had any relevance to their conventional procedures. But attitudes have greatly changed, in great part due to the Joint Division's programmes. The result was a high number of improved new varieties bred to date with the help of induced mutations, including some in this country. This publication is intended primarily to gather and put in order all information on the research and work on the use of induced mutations for plant breeding in the country. Its main purpose is to see if ensuing research efforts could be better coordinated, focused and enhanced in order to supplement the plant improvement programmes in the country. The task of collating the relevant information was not without difficulty since many of the work had been carried out long time ago; their objectives generally were quite broad; and the results essentially not published, with some exceptions. Section I begins with thefntroduction, giving a brief account of the developments of induced mutations in Malaysia, the facilities available in various institutions and the role played by the National Committee on the Use of Mutations in Plant Breeding. The collaborative efforts of IAEA and IFNCC are also briefly described here, together with all the activates which they had supported in the past. Section 11 briefly describes the induced mutations and how they are produced and utilised in the plant improvement programmes, taking into consideration the safety precautions required, and the requirements of different crop species. Section III describes in greater details all the research that had been carried out in the country. The

  5. Monotonicity of fitness landscapes and mutation rate control.

    Science.gov (United States)

    Belavkin, Roman V; Channon, Alastair; Aston, Elizabeth; Aston, John; Krašovec, Rok; Knight, Christopher G

    2016-12-01

    A common view in evolutionary biology is that mutation rates are minimised. However, studies in combinatorial optimisation and search have shown a clear advantage of using variable mutation rates as a control parameter to optimise the performance of evolutionary algorithms. Much biological theory in this area is based on Ronald Fisher's work, who used Euclidean geometry to study the relation between mutation size and expected fitness of the offspring in infinite phenotypic spaces. Here we reconsider this theory based on the alternative geometry of discrete and finite spaces of DNA sequences. First, we consider the geometric case of fitness being isomorphic to distance from an optimum, and show how problems of optimal mutation rate control can be solved exactly or approximately depending on additional constraints of the problem. Then we consider the general case of fitness communicating only partial information about the distance. We define weak monotonicity of fitness landscapes and prove that this property holds in all landscapes that are continuous and open at the optimum. This theoretical result motivates our hypothesis that optimal mutation rate functions in such landscapes will increase when fitness decreases in some neighbourhood of an optimum, resembling the control functions derived in the geometric case. We test this hypothesis experimentally by analysing approximately optimal mutation rate control functions in 115 complete landscapes of binding scores between DNA sequences and transcription factors. Our findings support the hypothesis and find that the increase of mutation rate is more rapid in landscapes that are less monotonic (more rugged). We discuss the relevance of these findings to living organisms.

  6. Recent progress and future perspectives regarding mutation breeding at the Institute of Radiation Breeding

    International Nuclear Information System (INIS)

    Nakagawa, Hitoshi

    2006-01-01

    Number of mutation species in the world is stated by some literature. 202 species are bread in Japan, which consists of 151 (by radiation), 20 (chemicals) and 31 (culture). The mutation indirect use species obtained 176 of rice, 3 wheat, 6 barleys, 8 soybeans, 3 tomatoes and 4 others. Low allergen rice, low glutelin rice, globulin deletion rice, disease resistant pear and apple, chrysanthemum and rose by radiation were studied. Control of mutation, genetics analysis, molecular scientific determination of mutation such as scale of mutation and RNA interference are reported. Advanced Radiation Application Research Center was build in Korea, 2005. Malaysian Institute for Nuclear Technology Research (MINT) is being built in Malaysia. Forum for Nuclear Cooperation in Asia (FNCA) is promoting radiation breeding in Japan. (S.Y.)

  7. Analysis of mutant frequencies and mutation spectra in hMTH1 knockdown TK6 cells exposed to UV radiation

    Energy Technology Data Exchange (ETDEWEB)

    Fotouhi, Asal [Center for Radiation Protection Research, Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University (Sweden); Hagos, Winta Woldai [Department of Toxicogenetics, Leiden University Medical Center, Leiden (Netherlands); Ilic, Marina; Wojcik, Andrzej; Harms-Ringdahl, Mats [Center for Radiation Protection Research, Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University (Sweden); Gruijl, Frank de [Department of Dermatology, Leiden University Medical Center, Leiden (Netherlands); Mullenders, Leon; Jansen, Jacob G. [Department of Toxicogenetics, Leiden University Medical Center, Leiden (Netherlands); Haghdoost, Siamak, E-mail: Siamak.Haghdoost@su.se [Center for Radiation Protection Research, Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University (Sweden)

    2013-11-15

    Highlights: • hMTH1 protects cells from mutagenesis induced by UVA and UVB, but not UVC. • No protective role of hMTH1 in cell survival post UVB and UVC irradiation. • hMTH1 prevents induction of transition-type mutations at AT and GC post UVA irradiation. • 2-OH-dATP rather than 8-oxo-dGTP in the nucleotide pool likely contributes in UVA-induced mutations. - Abstract: Ultraviolet radiation is a highly mutagenic agent that damages the DNA by the formation of mutagenic photoproducts at dipyrimidine sites and by oxidative DNA damages via reactive oxygen species (ROS). ROS can also give rise to mutations via oxidation of dNTPs in the nucleotide pool, e.g. 8-oxo-dGTP and 2-OH-dATP and subsequent incorporation during DNA replication. Here we show that expression of human MutT homolog 1 (hMTH1) which sanitizes the nucleotide pool by dephosphorylating oxidized dNTPs, protects against mutagenesis induced by long wave UVA light and by UVB light but not by short wave UVC light. Mutational spectra analyses of UVA-induced mutations at the endogenous Thymidine kinase gene in human lymphoblastoid cells revealed that hMTH1 mainly protects cells from transitions at GC and AT base pairs.

  8. The split-sting trait in Apis mellifera induced by cobalt 60 gamma radiation; Inducao do carater ferrao aberto em abelhas Apis mellifera por irradiacao gama de cobalto-60

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Vera Lucia Maciel

    1993-12-31

    The Split-Sting (SS) trait in honey bees, induced by gamma radiation, was discovered by Soares (1975). Bees with this trait are unable to sting, because the parts that compose the sting are separated. Many studies have been done in order to understand this new mutation. We studied the effect of gamma radiation on induction of the SS trait in feral bee strains. The doses were applied to the phase of larvae of queens with 5 days old. The following results were obtained: all doses of radiation induced the SS trait. There was an increase in the percentage of queens with SS with an increase in radiation dose; the SS trait induced by radiation is probably phenocopy; SS bees were observed in nature; increase of the rate mortality and malformation with an increase in radiation dose. (author) 55 refs., 8 figs., 6 tabs.

  9. The split-sting trait in Apis mellifera induced by cobalt 60 gamma radiation; Inducao do carater ferrao aberto em abelhas Apis mellifera por irradiacao gama de cobalto-60

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Vera Lucia Maciel

    1994-12-31

    The Split-Sting (SS) trait in honey bees, induced by gamma radiation, was discovered by Soares (1975). Bees with this trait are unable to sting, because the parts that compose the sting are separated. Many studies have been done in order to understand this new mutation. We studied the effect of gamma radiation on induction of the SS trait in feral bee strains. The doses were applied to the phase of larvae of queens with 5 days old. The following results were obtained: all doses of radiation induced the SS trait. There was an increase in the percentage of queens with SS with an increase in radiation dose; the SS trait induced by radiation is probably phenocopy; SS bees were observed in nature; increase of the rate mortality and malformation with an increase in radiation dose. (author) 55 refs., 8 figs., 6 tabs.

  10. Protection against radiation-induced mutations at the hprt locus by spermine and N,N double-prime-(dithiodi-2,1-ethanediyl)bis-1,3-propanediamine (WR-33278)

    International Nuclear Information System (INIS)

    Grdina, D.J.; Schwartz, J.L.; Shigematsu, N.

    1993-06-01

    The polyamine spermine and the disulfide NN double-prime-(dithiodi-2,1-ethanediyl)bis-1,3-propanediamine (WR-33278) are structurally similar agents capable of binding to DNA. WR-33278 is the disulfide moiety of the clinically studied radioprotective agent (WR-2721). Because of their structural similarities, it was of interest to characterize and compare their radioprotective properties using the endpoints of cell survival and mutation induction at the hypoxanthine-guanine phosphoribosyl transferase (hprt) locus in Chinese hamster AA8 cells. In order to facilitate both the uptake of VM-33278 into cells and the direct comparison between the protective properties of WR-33278 and spermine, these agents were electroporated into cells. Electroporation alone reduced cell survival to 75% but had no effect on hprt mutation frequency. The electroporation of either spermine or WR-33278 at concentrations greater than 0.01 mM was extremely toxic. The exposure of cells to both electroporation and irradiation gave rise to enhanced cell killing and mutation induction. Cell survival values at a radiation dose of 750 cGy were enhanced by factors of 1.3 and 1.8 following electroporation of 0.01 mM of spermine and WR-33278, respectively, 30 min prior to irradiation. Neither agent was protective at a concentration of 0.001 mM. Protection against radiation-induced hprt mutations was observed for both spermine and WR-33278 under all experimental conditions tested

  11. The genetics of radiation-induced and sporadic osteosarcoma: a unifying theory?

    International Nuclear Information System (INIS)

    Rosemann, Michael; Kuosaite, Virginija; Nathrath, Michaela; Atkinson, Michael J.

    2002-01-01

    Cancer is a disease of the genome, with the neoplastic phenotype being passed from one cell generation to the other. Radiation-induced cancer has often been considered to represent a unique entity amongst neoplasia, with the energy deposition being held responsible for both direct (gene mutations) and indirect (bystander effects, induced instability etc) alterations to the cellular genome. However, radiogenic tumours in man and experimental animals appear to be physiologically and genetically indistinguishable from their sporadic counterparts, suggesting that the aetiologies of these two tumour types are in fact closely related. We have conducted a general screen of the genetic alterations in radiation-induced mouse osteosarcoma, a tumour that is histopathologically indistinguishable from human sporadic osteosarcoma. Comparison of the two tumour types indicates the existence of a common set of genetic changes, providing additional evidence to support the concept that the molecular pathology of radiation-induced malignancy is no different to that of sporadic cancers. (author)

  12. Spontaneous mutation rate in Chinese hamster cell clones differing in UV-sensitivity

    International Nuclear Information System (INIS)

    Manuilova, E.S.; Bagrova, A.M.; Moskovskij Gosudarstvennyj Univ.

    1983-01-01

    The spontaneous rate of appearance of mutations to 6-mercaptopurine (6 MP) resistence in the cells of CHR2 and CHs2 clones dofferent in sensitivity to lethal and matagenous effect of UV-rays, is investigated. Increased UV-sensitivity of CHs2 clone is caused by the violation of postreplicative DNA reparation. It is established that the purity of spontaneously occuring mutations in both clones turns out to be similar, i.e. (1.5-1.8)x10 -5 for the cell pergeneration. It is shown that the effect of postreplicative DNA reparation in the cells of chinese hamster is not connected with the increase of spontaneous mutation ability. The problem on the possible role of reparation in the mechanism of appearance of spontaneous and induced mutations in the cells of Chinese hamster with increased UV-sensitivity is discussed

  13. Genetic effects of ionizing radiation – some questions with no answers

    International Nuclear Information System (INIS)

    Mosse, Irma B.

    2012-01-01

    There are a lot of questions about genetic effects of ionizing radiation, the main one is does ionizing radiation induce mutations in humans? There is no direct evidence that exposure of parents to radiation leads to excess heritable disease in offspring. What is the difference between human and other species in which radiation induced mutations are easily registered? During evolution germ cell selection ex vivo has been changed to a selection in vivo and we cannot observe such selection of radiation damaged cells in human. Low radiation doses – are they harmful or beneficial? The “hormesis” phenomenon as well as radioadaptive response proves positive effects of low radiation dose. Can analysis of chromosomal aberration rate in lymphocytes be used for dosimetry? Many uncontrolled factors may be responsible for significant mistakes of this method. Why did evolution preserve the bystander effect? This paper is discussion one and its goal is to pay attention on some effects of ionizing radiation. - Highlights: ► There are a lot of questions about genetic effects of ionizing radiation. ► Does ionizing radiation induce mutations in human? ► During evolution germ cell selection ex vivo has been changed to a selection in vivo. ► Radioadaptive response proves positive effects of low radiation doses. ► Many uncontrolled factors may be responsible for significant biodosimetry mistakes.

  14. Estimating the Per-Base-Pair Mutation Rate in the Yeast Saccharomyces cerevisiae

    OpenAIRE

    Lang, Gregory I.; Murray, Andrew W.

    2008-01-01

    Although mutation rates are a key determinant of the rate of evolution they are difficult to measure precisely and global mutations rates (mutations per genome per generation) are often extrapolated from the per-base-pair mutation rate assuming that mutation rate is uniform across the genome. Using budding yeast, we describe an improved method for the accurate calculation of mutation rates based on the fluctuation assay. Our analysis suggests that the per-base-pair mutation rates at two genes...

  15. Effects of near-ultraviolet light on mutations, intragenic and intergenic recombinations in Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Machida, Isamu; Saeki, Tetsuya; Nakai, Sayaka

    1986-01-01

    The effects of far and near ultraviolet light on mutations, intragenic and intergenic recombinations were compared in diploid strains of Saccharomyces cerevisiae. At equivalent survival levels there was not much difference in the induction of nonsense and missense mutations between far- and near-UV radiations. However, frameshift mutations were induced more frequently by near-UV than by far-UV radiation. Near-UV radiation induced intragenic recombination as efficiently as far-UV radiation. A strikingly higher frequency was observed for the intergenic recombination induced by near-UV radiation than by far-UV radiation when compared at equivalent survival levels. Photoreactivation reduced the frequency only slightly in far-UV induced intergenic recombination and not at all in near-UV induction. These results indicate that near-UV damage involves strand breakage in addition to pyrimidine dimers and other lesions induced, whereas far-UV damage consists largely of photoreactivable lesions, pyrimidine dimers, and near-UV induced damage is more efficient for the induction of crossing-over. (Auth.)

  16. Studies of human mutation rates: Progress report

    International Nuclear Information System (INIS)

    Neel, J.V.

    1988-01-01

    Progress was recorded between January 1 and July 1, 1987 on a project entitled ''Studies of Human Mutation Rates''. Studies underway include methodology for studying mutation at the DNA level, algorithms for automated analyses of two-dimensional polyacrylamide DNA gels, theoretical and applied population genetics, and studies of mutation frequency in A-bomb survivors

  17. Beta induced Bremsstrahlung dose rate in concrete shielding

    International Nuclear Information System (INIS)

    Manjunatha, H.C.

    2013-01-01

    Dosimetric study of beta-induced Bremsstrahlung in concrete is importance in the field of radiation protection. The efficiency, intensity and dose rate of beta induced Bremsstrahlung by 113 pure beta nuclides in concrete shielding is computed. The Bremsstrahlung dosimetric parameters such as the efficiency (yield), Intensity and dose rate of Bremsstrahlung are low for 199 Au and high for 104 Tc in concrete. The efficiency, Intensity and dose rate of Bremsstrahlung increases with maximum energy of beta nuclide (Emax) and modified atomic number (Zmod) of the target. The estimated Bremsstrahlung efficiency, Intensity and dose rate are useful in the calculations photon track-length distributions. These parameters are useful to determine the quality and quantity of the radiation (known as the source term). Precise estimation of this source term is very important in planning of radiation shielding. (author)

  18. Induced mutations in chickpea (Cicer arietinum L.) II. frequency and spectrum of chlorophyll mutations

    International Nuclear Information System (INIS)

    Kharkwal, M.C.

    1998-01-01

    A comparative study of frequency and spectrum of chlorophyll mutations induced by two physical (gamma rays, fast neutrons) and two chemical mutagens (NMU, EMS) in relation to the effects in M1 plants and induction of mutations in M2 was made in four chickpea (Cicer arietinum L.) varieties, two desi (G 130 & H 214) one Kabuli (C 104) and one green seeded (L 345). The treatments included three doses each of gamma rays (400, 500 & 600 Gy) and fast neutrons (5, 10 & 15 Gy) and two concentrations with two different durations of two chemical mutagens, NMU [0.01% (20h), & 0.02% (8h)] and EMS [0.1% (20h) & 0.2% (8h)]. The frequencies and spectrum of three different kinds of induced chlorophyll mutations in the order albina (43.5%), chlorina (27.3%) and xantha (24.2%) were recorded. Chemical mutagens were found to be efficient in inducing chlorophyll mutations in chickpea. Highest frequency of mutations was observed in green seeded var. L 345 (83% of M1 families and 19.9/1000 M2 plants). Kabuli var. C 104 was least responsive for chlorophyll mutations

  19. Variable mutation rates as an adaptive strategy in replicator populations.

    Directory of Open Access Journals (Sweden)

    Michael Stich

    2010-06-01

    Full Text Available For evolving populations of replicators, there is much evidence that the effect of mutations on fitness depends on the degree of adaptation to the selective pressures at play. In optimized populations, most mutations have deleterious effects, such that low mutation rates are favoured. In contrast to this, in populations thriving in changing environments a larger fraction of mutations have beneficial effects, providing the diversity necessary to adapt to new conditions. What is more, non-adapted populations occasionally benefit from an increase in the mutation rate. Therefore, there is no optimal universal value of the mutation rate and species attempt to adjust it to their momentary adaptive needs. In this work we have used stationary populations of RNA molecules evolving in silico to investigate the relationship between the degree of adaptation of an optimized population and the value of the mutation rate promoting maximal adaptation in a short time to a new selective pressure. Our results show that this value can significantly differ from the optimal value at mutation-selection equilibrium, being strongly influenced by the structure of the population when the adaptive process begins. In the short-term, highly optimized populations containing little variability respond better to environmental changes upon an increase of the mutation rate, whereas populations with a lower degree of optimization but higher variability benefit from reducing the mutation rate to adapt rapidly. These findings show a good agreement with the behaviour exhibited by actual organisms that replicate their genomes under broadly different mutation rates.

  20. Comparative effects of ionizing radiation and two gaseous chemical mutagens on somatic mutation induction in one mutable and two non-mutable clones of Tradescantia

    International Nuclear Information System (INIS)

    Nauman, C.H.; Sparrow, A.H.; Schairer, L.A.

    1976-01-01

    The X-ray dose responses of mutable clone 0106 of Tradescantia (mutable for blue to pink), and its parent clone 02 have been determined for pink and colorless mutations in stamen hair cells, and are compared to the previously determined X-ray response for pink mutations of a third unrelated clone, clone 4430 (hybrid of T. subacaulis and T. hirsutiflora). X-ray response curves are compared to the response curves of the same three clones after exposure to the gaseous phase of the alkylating agent ethyl methanesulfate (EMS) and the fumigant and gasoline additive 1,2-dibromoethane (DBE). X-irradiation induces a pink mutation rate in mutable clone 0106 that is significantly higher than that of the nearly identical pink mutation rates in clones 02 and 4430. However, the colorless mutation rates of clones 02 and 0106 are not significantly different from one another. In clones 02 and 0106, pink mutations occur more frequently than colorless mutations at lower doses, but colorless dose-response curves saturate at higher doses than do those for pink mutations. Exposure-response curves for EMS and DBE have characteristics similar to those of X-ray response curves: exponential rise followed by an area of saturation. However, it was found that the relative sensitivities of the three clones to the gaseous mutagens and to ionizing radiation do not parallel one another. Where clones 02 and 4430 are equally sensitive to X-rays, at equal mutagen concentration clone 4430 is 6-7 times more sensitive to EMS and 7-9 times more sensitive to DBE than is clone 02. Mutable clone 0106 shows intermediate sensitivities to both EMS and DBE

  1. Progress in hprt mutation assay and its application in radiation biology

    International Nuclear Information System (INIS)

    He Jing; Li Qiang

    2008-01-01

    hprt gene is an X-linked locus that has been well studied and widely used as a bio-marker in mutation detection, hprt mutation assay is a gene mutation test system in mammalian cells in vitro which has been used as a biological dosimeter. In this paper, the biological characteristics of hprt gene, hprt mutation detection methodology and the application of hprt mutation assay in radiation biology are comprehensively reviewed. (authors)

  2. Radiation-induced mutagenicity in repair deficient Chinese hamster ovary (CHO) mutants

    International Nuclear Information System (INIS)

    Tesmer, J.G.; Saunders, E.H.; Chen, D.J.

    1987-01-01

    To determine if there is a relationship between DNA double-strand break repair and mutagenicity the authors utilized two x-ray sensitive mutants of Chinese hamster ovary cells along with the parental line K1. The two mutant lines xrs-5 and xrs-6, which have different DSB repair capabilities, were used to determine cell killing and 6-thioguanine resistance (6TG/sup r/) mutation frequencies induced by either x-rays of α-particles, x-ray survival data indicated the two mutant lines have similar sensitivity and are 5-7 fold more sensitive than the parental line K1. The mutant lines are also sensitive to α-particles but to a lesser extent. The authors' 6TG mutation data indicated that the two mutant lines are hypermutable. When mutation frequencies were plotted against the log of survival, mutation frequency at a given survival level was greater in mutant cell population than in parental K1 cells. Their results support the notion that repair of DSB play an important role in the expression of radiation-induced cell killing and mutagenicity

  3. Effect of radiation on the long term productivity of a plant based CELSS

    International Nuclear Information System (INIS)

    Thompson, B.G.; Lake, B.H.

    1987-01-01

    Mutations occur at a higher rate in space than under terrestrial conditions, primarily due to an increase in radiation levels. These mutations may effect the productivity of plants found in a controlled ecological life support system (CELSS). Computer simulations of plants with different ploidies, modes of reproduction, lethality thresholds, viability thresholds and susceptibilities to radiation induced mutations were performed under space normal and solar flare conditions. These simulations identified plant characteristics that would enable plants to retain high productivities over time in a CELSS

  4. Simulating Space Radiation-Induced Breast Tumor Incidence Using Automata.

    Science.gov (United States)

    Heuskin, A C; Osseiran, A I; Tang, J; Costes, S V

    2016-07-01

    Estimating cancer risk from space radiation has been an ongoing challenge for decades primarily because most of the reported epidemiological data on radiation-induced risks are derived from studies of atomic bomb survivors who were exposed to an acute dose of gamma rays instead of chronic high-LET cosmic radiation. In this study, we introduce a formalism using cellular automata to model the long-term effects of ionizing radiation in human breast for different radiation qualities. We first validated and tuned parameters for an automata-based two-stage clonal expansion model simulating the age dependence of spontaneous breast cancer incidence in an unexposed U.S. We then tested the impact of radiation perturbation in the model by modifying parameters to reflect both targeted and nontargeted radiation effects. Targeted effects (TE) reflect the immediate impact of radiation on a cell's DNA with classic end points being gene mutations and cell death. They are well known and are directly derived from experimental data. In contrast, nontargeted effects (NTE) are persistent and affect both damaged and undamaged cells, are nonlinear with dose and are not well characterized in the literature. In this study, we introduced TE in our model and compared predictions against epidemiologic data of the atomic bomb survivor cohort. TE alone are not sufficient for inducing enough cancer. NTE independent of dose and lasting ∼100 days postirradiation need to be added to accurately predict dose dependence of breast cancer induced by gamma rays. Finally, by integrating experimental relative biological effectiveness (RBE) for TE and keeping NTE (i.e., radiation-induced genomic instability) constant with dose and LET, the model predicts that RBE for breast cancer induced by cosmic radiation would be maximum at 220 keV/μm. This approach lays the groundwork for further investigation into the impact of chronic low-dose exposure, inter-individual variation and more complex space radiation

  5. Variation in RNA virus mutation rates across host cells.

    Directory of Open Access Journals (Sweden)

    Marine Combe

    2014-01-01

    Full Text Available It is well established that RNA viruses exhibit higher rates of spontaneous mutation than DNA viruses and microorganisms. However, their mutation rates vary amply, from 10(-6 to 10(-4 substitutions per nucleotide per round of copying (s/n/r and the causes of this variability remain poorly understood. In addition to differences in intrinsic fidelity or error correction capability, viral mutation rates may be dependent on host factors. Here, we assessed the effect of the cellular environment on the rate of spontaneous mutation of the vesicular stomatitis virus (VSV, which has a broad host range and cell tropism. Luria-Delbrück fluctuation tests and sequencing showed that VSV mutated similarly in baby hamster kidney, murine embryonic fibroblasts, colon cancer, and neuroblastoma cells (approx. 10(-5 s/n/r. Cell immortalization through p53 inactivation and oxygen levels (1-21% did not have a significant impact on viral replication fidelity. This shows that previously published mutation rates can be considered reliable despite being based on a narrow and artificial set of laboratory conditions. Interestingly, we also found that VSV mutated approximately four times more slowly in various insect cells compared with mammalian cells. This may contribute to explaining the relatively slow evolution of VSV and other arthropod-borne viruses in nature.

  6. Radiation induced mutant crop varieties: accomplishment and societal deployment

    International Nuclear Information System (INIS)

    D'Souza, S.F.

    2009-01-01

    One of the peaceful applications of atomic energy is in the field of agriculture. It finds application in crop improvement, crop nutrition, crop protection and food preservation. Genetic improvement of crop plants is a continuous endeavor. Success of a crop improvement programme depends on the availability of large genetic variability, which a plant breeder can combine to generate new varieties. In nature, occurrence of natural variability in the form of spontaneous mutations is extremely low (roughly 10 -6 ), which can be enhanced to several fold (approximately 10 -3 ) by using ionizing radiations or chemical mutagens. Radiation induced genetic variability in crop plants is a valuable resource from which plant breeder can select and combine different desired characteristics to produce better crop varieties. Crop improvement programmes at Bhabha Atomic Research Centre (BARC) envisage radiation based induced mutagenesis along with recombination breeding in country's important cereals (rice and wheat), oilseeds (groundnut, mustard, soybean and sunflower), grain legumes (blackgram, mungbean, pigeonpea and cowpea), banana and sugarcane

  7. On the effect of hyperaldosteronism-inducing mutations in Na/K pumps.

    Science.gov (United States)

    Meyer, Dylan J; Gatto, Craig; Artigas, Pablo

    2017-11-06

    Primary aldosteronism, a condition in which too much aldosterone is produced and that leads to hypertension, is often initiated by an aldosterone-producing adenoma within the zona glomerulosa of the adrenal cortex. Somatic mutations of ATP1A1, encoding the Na/K pump α1 subunit, have been found in these adenomas. It has been proposed that a passive inward current transported by several of these mutant pumps is a "gain-of-function" activity that produces membrane depolarization and concomitant increases in aldosterone production. Here, we investigate whether the inward current through mutant Na/K pumps is large enough to induce depolarization of the cells that harbor them. We first investigate inward currents induced by these mutations in Xenopus Na/K pumps expressed in Xenopus oocytes and find that these inward currents are similar in amplitude to wild-type outward Na/K pump currents. Subsequently, we perform a detailed functional evaluation of the human Na/K pump mutants L104R, delF100-L104, V332G, and EETA963S expressed in Xenopus oocytes. By combining two-electrode voltage clamp with [ 3 H]ouabain binding, we measure the turnover rate of these inward currents and compare it to the turnover rate for outward current through wild-type pumps. We find that the turnover rate of the inward current through two of these mutants (EETA963S and L104R) is too small to induce significant cell depolarization. Electrophysiological characterization of another hyperaldosteronism-inducing mutation, G99R, reveals the absence of inward currents under many different conditions, including in the presence of the regulator FXYD1 as well as with mammalian ionic concentrations and body temperatures. Instead, we observe robust outward currents, but with significantly reduced affinities for intracellular Na + and extracellular K + Collectively, our results point to loss-of-function as the common mechanism for the hyperaldosteronism induced by these Na/K pump mutants. © 2017 Meyer et al.

  8. Mutagenesis in mammalian cells can be modulated by radiation-induced voltage-dependent potassium channels

    International Nuclear Information System (INIS)

    Saad, A.H.; Zhou, L.Y.; Lambe, E.K.; Hahn, G.M.

    1994-01-01

    In mammalian cells, little is known about the initial events whose ultimate consequence is mutagenesis or DNA repair. The role the plasma membrane may play as an initiator of such a pathway is not understood. We show, for the first time, that membrane voltage-dependent potassium (K + ) currents, activated by ionizing radiation play a significant role in radiation mutagenesis. Specifically, we show that the frequency of mutation at the HGPRT locus is increased as expected to 37.6±4.0 mutations per 100,000 survivors by 800 cGy of ionizing radiation from a spontaneous frequency of 1.5±1.5. This increase, however, is abolished if either K + channel blocker, CsCl or BaCl 2 , is present for 2h following irradiation of the cells. RbCl, chemically similar to CsCl but known not to block K + channels, is ineffective in reducing the mutation frequency. Treatment of cells with CsCl or BaCl 2 had no effect on radiation-induced cell killing

  9. Expression of MDM2 in an acute lymphocytic leukemia mice model induced by γ-radiation

    International Nuclear Information System (INIS)

    Huang Yuecheng; Cai Jianming; Han Ling; Gao Fu; Cui Jianguo; Gao Jianguo

    2004-01-01

    Objective: To investigate the role of the MDM 2 in the process of carcinogenesis induced by γ-rays and its molecular mechanisms. Methods: Animal model of radiation-induced leukemia was established by γ-irradiation. According to the histological and morphological results, mice tissues were divided into three groups: cancerization group, incancerization group and control group. Expression of MDM 2 protein and mRNA in thymus/bone marrow was detected with Western blot and in situ hybridization (ISH), respectively. The authors also examined the protein phosphorylation level of MDM 2 protein by immunoprecipitation (IP). PCR-SSCP was performed to detect gene mutation. Results: A mice leukemia model was successfully established as verified by pathological findings and confirmed by transplantation test in nude mice. The protein expression in thymus/bone marrow in irradiation groups was significantly higher than that in controls (P 2 was found to be hyper-phosphorylated in the cancerization group as compared with other groups. No gene mutation was detected by SSCP/silver-staining assay in the tumor samples. Conclusion: MDM 2 may be involved in the development and progression of leukemia induced by γ-irradiation. The over-expression but not gene mutation may be responsible for malignant transformation induced by radiation. Phosphorylation is at least partly attributed to activation of MDM 2

  10. Improved short-stature rice created by radiation-induced mutation

    International Nuclear Information System (INIS)

    1977-01-01

    A new mutant variety of rice, named Calrose 76, has recently been released to farmers in California. The mutant was the result of irradiating seeds of the rice variety Calrose with gamma rays from a cobalt-60 source. The variety is the result of co-operative research between Dr. J.N. Rutger, U.S. Department of Agriculture research geneticist at Davis, California, Prof. M.L. Peterson, University of California, and Dr. Chao-Hwa Hu, an IAEA fellow. The mutant that was ultimately released as a new variety was selected in the second generation following irradiation of the Calrose seeds. Selections were also made in a non-irradiated control population, but none proved to be desirable. After its selection in 1971, the mutant was subsequently tested for several years for agronomic performance, grain yield and quality characteristics. It was found to have the same yielding capacity as the widely grown check variety, CS-M3. It also did not differ in seedling vigour or in heading date, but its mature stem is about 35 cm shorter and less susceptible to lodging. Therefore, it yields more grain under conditions of high soil fertility. The short stature is inherited by a single recessive gene, allelic to the gene for short stature widely used in rice cultivars of the International Rice Research Institute in the Philippines (IRRI). The radiation-induced mutant has the advantage that the gene for short stature now exists in a genotype which is adapted to Californian conditions and which possesses the required cold tolerance and grain qualities. Attempts to transfer short stature from the tropical variety IR8 (produced by IRRI) have been complicated by sterility, cold susceptibility, and unacceptable grain quality. The radiation-induced mutant is used now also in crosses to confer the desired short stature to other rice varieties. (author)

  11. Improved short-stature rice created by radiation-induced mutation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1977-06-15

    A new mutant variety of rice, named Calrose 76, has recently been released to farmers in California. The mutant was the result of irradiating seeds of the rice variety Calrose with gamma rays from a cobalt-60 source. The variety is the result of co-operative research between Dr. J.N. Rutger, U.S. Department of Agriculture research geneticist at Davis, California, Prof. M.L. Peterson, University of California, and Dr. Chao-Hwa Hu, an IAEA fellow. The mutant that was ultimately released as a new variety was selected in the second generation following irradiation of the Calrose seeds. Selections were also made in a non-irradiated control population, but none proved to be desirable. After its selection in 1971, the mutant was subsequently tested for several years for agronomic performance, grain yield and quality characteristics. It was found to have the same yielding capacity as the widely grown check variety, CS-M3. It also did not differ in seedling vigour or in heading date, but its mature stem is about 35 cm shorter and less susceptible to lodging. Therefore, it yields more grain under conditions of high soil fertility. The short stature is inherited by a single recessive gene, allelic to the gene for short stature widely used in rice cultivars of the International Rice Research Institute in the Philippines (IRRI). The radiation-induced mutant has the advantage that the gene for short stature now exists in a genotype which is adapted to Californian conditions and which possesses the required cold tolerance and grain qualities. Attempts to transfer short stature from the tropical variety IR8 (produced by IRRI) have been complicated by sterility, cold susceptibility, and unacceptable grain quality. The radiation-induced mutant is used now also in crosses to confer the desired short stature to other rice varieties. (author)

  12. Radiation-chemical discussion on inverse dose-rate effect observed in radiation-induced strand breaks of plasmid DNA

    International Nuclear Information System (INIS)

    Masuda, Takahiro

    1994-01-01

    Experimental results of inverse dose-rate effect, so-called Kada Effects, which was published by Takakura and her coworkers on radiation-induced strand breaks of plasmid DNA in aerated aqueous solution, have been kinetically analyzed and discussed on the basis of radiation chemistry. the kinetic analysis indicates that there are two possible mechanisms; 1) equilibrium mixture of O 2 - and HO 2 is responsible for strand breaks of DNA, and 2) peroxyl radical produced from citrate is effective for the strand breaks. However, the detailed kinetic analysis revealed that the latter is improbable because unimolecular decay of the peroxyl radical must be assumed to be negligible for its participation despite fast decay of analogous organic peroxyl radicals. The analysis has also given 9.93±0.10 dm 3 mol -1 s -1 per nucleotide unit, which corresponds to 7.62 x 10 4 dm 3 mol -1 s -1 per DNA molecule, as the rate constant for the reaction of the equilibrium mixture with plasmid pBR 322 DNA. Furthermore the probability that the reaction of the mixture with a nucleotide unit of DNA leads to strand breaks was obtained to be 3.36 x 10 -3 for gamma-irradiated system and 1.98 x 10 -3 for beta-irradiated system, respectively. (author)

  13. Induced mutations for human welfare through agriculture

    International Nuclear Information System (INIS)

    Patil, S.A.

    2009-01-01

    Full text: Use of induced mutation for crop improvement started in 1920's. It gained momentum in 1960's when IAEA and FAO started training and guidance and funds were made available for undertaking mutation breeding. IARI established a Gamma Garden and a separate institution was carved by name 'Nuclear Research Laboratory' in 1970's. ICAR Institutes and State Agriculture Universities started using this facility for crop improvement. Similarly, BARC started extending its help for irradiating the seed material specially X-rays and it became one of the major source of generating variability for crop improvement. Induced mutation has resulted in development of more than 3000 varieties of different food, feed, fruit, vegetables and flowers. Apart from direct use of mutants as cultivars, mutants have played a vital role in creating useful variation for application in basic research and gene discovery. It has helped in increasing yield through use of heterosis by inducing male sterility. It has been used for creating useful variation for changing grain composition to improve nutrition and grain quality parameters, for tolerance against abiotic and biotic stresses. Gene sequencing and related technologies have opened up new application of induced mutations. In model organisms induced mutations provide new opportunities for identification of genes/bio-chemical, cellular, developmental or functional pathways. The use of stable isotopes in basic research is of fundamental use in crop improvement. Apart from crop improvement the nuclear technology has been used for numerous other applications in Agriculture such as soil fertility, plant nutrition, use of fertilizer and irrigation, control of insect pest and storage. In recent decades BARC has come in a big way through funding for projects to State Agricultural Universities and ICAR Institutes and has signed MoU's with few of the Agriculture Universities for testing and popularizing their identified field crop varieties in

  14. Radiation induced structural changes in alpha-copper-zinc alloys

    International Nuclear Information System (INIS)

    Schuele, W.; Gieb, M.

    1991-01-01

    During irradiation of alpha-copper-zinc alloys with high energy electrons and protons a decrease of the electrical resistivity due to an increase of the degree of short range order is observed through radiation enhanced diffusion followed by an increase of the electrical resistivity through the formation of radiation induced interstitial clusters. The initial formation rate of interstitial clusters increases about linearly with the displacement rate for electron and proton irradiation. The largest initial formation rate is found between 60 and 130 0 C becoming negligibly small above 158 0 C and decreases drastically below 60 0 C. The dynamic steady state interstitial cluster concentration increases with decreasing irradiation temperature in the investigated temperature range between 158 and 40 0 C. Above 158 0 C the formation rate of interstitial clusters is negligibly small. Thus the transition temperature for radiation induced interstitial cluster formation is 158 0 C, depending mainly on the migration activation energy of vacancies. The radiation induced interstitial clusters are precipitates in those alloys in which the diffusion rate of the undersized component atoms via an interstitialcy diffusion mechanism is larger than that of the other atoms

  15. An evolutionary reduction principle for mutation rates at multiple Loci.

    Science.gov (United States)

    Altenberg, Lee

    2011-06-01

    A model of mutation rate evolution for multiple loci under arbitrary selection is analyzed. Results are obtained using techniques from Karlin (Evolutionary Biology, vol. 14, pp. 61-204, 1982) that overcome the weak selection constraints needed for tractability in prior studies of multilocus event models.A multivariate form of the reduction principle is found: reduction results at individual loci combine topologically to produce a surface of mutation rate alterations that are neutral for a new modifier allele. New mutation rates survive if and only if they fall below this surface-a generalization of the hyperplane found by Zhivotovsky et al. (Proc. Natl. Acad. Sci. USA 91, 1079-1083, 1994) for a multilocus recombination modifier. Increases in mutation rates at some loci may evolve if compensated for by decreases at other loci. The strength of selection on the modifier scales in proportion to the number of germline cell divisions, and increases with the number of loci affected. Loci that do not make a difference to marginal fitnesses at equilibrium are not subject to the reduction principle, and under fine tuning of mutation rates would be expected to have higher mutation rates than loci in mutation-selection balance.Other results include the nonexistence of 'viability analogous, Hardy-Weinberg' modifier polymorphisms under multiplicative mutation, and the sufficiency of average transmission rates to encapsulate the effect of modifier polymorphisms on the transmission of loci under selection. A conjecture is offered regarding situations, like recombination in the presence of mutation, that exhibit departures from the reduction principle. Constraints for tractability are: tight linkage of all loci, initial fixation at the modifier locus, and mutation distributions comprising transition probabilities of reversible Markov chains.

  16. Detection of induced male germline mutation: Correlations and comparisons between traditional germline mutation assays, transgenic rodent assays and expanded simple tandem repeat instability assays

    Energy Technology Data Exchange (ETDEWEB)

    Singer, Timothy M. [Mutagenesis Section, Environmental and Occupational Toxicology Division, Safe Environments Programme, 0803A, Health Canada, Ottawa, Ont., K1A 0K9 (Canada); Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ont., K1S 5B6 (Canada); Lambert, Iain B. [Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ont., K1S 5B6 (Canada); Williams, Andrew [Biostatistics and Epidemiology Division, Safe Environments Programme, 6604B, Health Canada, Ottawa, Ont., K1A 0K9 (Canada); Douglas, George R. [Mutagenesis Section, Environmental and Occupational Toxicology Division, Safe Environments Programme, 0803A, Health Canada, Ottawa, Ont., K1A 0K9 (Canada); Yauk, Carole L. [Mutagenesis Section, Environmental and Occupational Toxicology Division, Safe Environments Programme, 0803A, Health Canada, Ottawa, Ont., K1A 0K9 (Canada)]. E-mail: carole_yauk@hc-sc.gc.ca

    2006-06-25

    Several rodent assays are capable of monitoring germline mutation. These include traditional assays, such as the dominant lethal (DL) assay, the morphological specific locus (SL) test and the heritable translocation (HT) assay, and two assays that have been developed more recently-the expanded simple tandem repeat (ESTR) and transgenic rodent (TGR) mutation assays. In this paper, we have compiled the limited amount of experimental data that are currently available to make conclusions regarding the comparative ability of the more recently developed assays to detect germline mutations induced by chemical and radiological agents. The data suggest that ESTR and TGR assays are generally comparable with SL in detecting germline mutagenicity induced by alkylating agents and radiation, though TGR offered less sensitivity than ESTR in some cases. The DL and HT assays detect clastogenic events and are most susceptible to mutations arising in post-spermatogonial cells, and they may not provide the best comparisons with TGR and ESTR instability. The measurement of induced ESTR instability represents a relatively sensitive method of identifying agents causing germline mutation in rodents, and may also be useful for bio-monitoring exposed individuals in the human population. Any future use of the TGR and ESTR germline mutation assays in a regulatory testing context will entail more robust and extensive characterization of assay performance. This will require substantially more data, including experiments measuring multiple endpoints, a greatly expanded database of chemical agents and a focus on characterizing stage-specific activity of mutagens in these assays, preferably by sampling epididymal sperm exposed at defined pre-meiotic, meiotic and post-meiotic stages of development.

  17. Detection of induced male germline mutation: Correlations and comparisons between traditional germline mutation assays, transgenic rodent assays and expanded simple tandem repeat instability assays

    International Nuclear Information System (INIS)

    Singer, Timothy M.; Lambert, Iain B.; Williams, Andrew; Douglas, George R.; Yauk, Carole L.

    2006-01-01

    Several rodent assays are capable of monitoring germline mutation. These include traditional assays, such as the dominant lethal (DL) assay, the morphological specific locus (SL) test and the heritable translocation (HT) assay, and two assays that have been developed more recently-the expanded simple tandem repeat (ESTR) and transgenic rodent (TGR) mutation assays. In this paper, we have compiled the limited amount of experimental data that are currently available to make conclusions regarding the comparative ability of the more recently developed assays to detect germline mutations induced by chemical and radiological agents. The data suggest that ESTR and TGR assays are generally comparable with SL in detecting germline mutagenicity induced by alkylating agents and radiation, though TGR offered less sensitivity than ESTR in some cases. The DL and HT assays detect clastogenic events and are most susceptible to mutations arising in post-spermatogonial cells, and they may not provide the best comparisons with TGR and ESTR instability. The measurement of induced ESTR instability represents a relatively sensitive method of identifying agents causing germline mutation in rodents, and may also be useful for bio-monitoring exposed individuals in the human population. Any future use of the TGR and ESTR germline mutation assays in a regulatory testing context will entail more robust and extensive characterization of assay performance. This will require substantially more data, including experiments measuring multiple endpoints, a greatly expanded database of chemical agents and a focus on characterizing stage-specific activity of mutagens in these assays, preferably by sampling epididymal sperm exposed at defined pre-meiotic, meiotic and post-meiotic stages of development

  18. NanoTIO2 (UV-Titan does not induce ESTR mutations in the germline of prenatally exposed female mice

    Directory of Open Access Journals (Sweden)

    Boisen Anne Mette

    2012-06-01

    Full Text Available Abstract Background Particulate air pollution has been linked to an increased risk of cardiovascular disease and cancer. Animal studies have shown that inhalation of air particulates induces mutations in the male germline. Expanded simple tandem repeat (ESTR loci in mice are sensitive markers of mutagenic effects on male germ cells resulting from environmental exposures; however, female germ cells have received little attention. Oocytes may be vulnerable during stages of active cell division (e.g., during fetal development. Accordingly, an increase in germline ESTR mutations in female mice prenatally exposed to radiation has previously been reported. Here we investigate the effects of nanoparticles on the female germline. Since pulmonary exposure to nanosized titanium dioxide (nanoTiO2 produces a long-lasting inflammatory response in mice, it was chosen for the present study. Findings Pregnant C57BL/6 mice were exposed by whole-body inhalation to the nanoTiO2 UV-Titan L181 (~42.4 mg UV-Titan/m3 or filtered clean air on gestation days (GD 8–18. Female C57BL/6 F1 offspring were raised to maturity and mated with unexposed CBA males. The F2 descendents were collected and ESTR germline mutation rates in this generation were estimated from full pedigrees (mother, father, offspring of F1 female mice (192 UV-Titan-exposed F2 offspring and 164 F2 controls. ESTR mutation rates of 0.029 (maternal allele and 0.047 (paternal allele in UV-Titan-exposed F2 offspring were not statistically different from those of F2 controls: 0.037 (maternal allele and 0.061 (paternal allele. Conclusions We found no evidence for increased ESTR mutation rates in F1 females exposed in utero to UV-Titan nanoparticles from GD8-18 relative to control females.

  19. Specitic gene alterations in radiation-induced tumorigenesis

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Joo Mee; Kang, Chang Mo; Lee, Seung Sook; Cho, Chul Koo; Bae, Sang Woo; Lee, Su Jae; Lee, Yun Sil [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

    2004-07-01

    To identify a set of genes involved in the development of radiation-induced tumorigenesis, we used DNA microarrays consisting of 1,176 mouse genes and compared expression profiles of radioresistant cells, designated NIH3T3-R1 and -R4. These cells were tumorigenic in a nude mouse grafting system, as compared to the parental NIH3T3 cells. Expressions of MDM2, CDK6 and CDC25B were found to increase more than 3-fold. Entactin protein levels were downregulated in NIH3T3-R1 and -R4 cells. Changes in expression genes were confirmed by reverse transcription-PCR or western blotting. When these genes were transfected to NIH3T3 cells, the CDC25B and MDM2 overexpressing NIH3T3 cells showed radioresistance, while 2 CDK6 overexpressing cells did not. In the case of entactin overexpressing NIH3T3-R1 or R-4 cells were still radioresistant. Furthermore, the CDC25B and MDM2 overexpressing cells grafted to nude mice, were tumorigenic. NIH3T3-R1 and R4 cells showed increased radiation-induced apoptosis, accompanied by faster growth rate, rather than and earlier radiation-induced G2/M phase arrest, suggesting that the radioresistance of NIH3T3-R1 and R4 cells was due to faster growth rate, rather than induction of apoptosis. In the case of MDM2 and CDC25B overexpressing cells, similar phenomena, such as increased apoptosis and faster growth rate, were shown. The above results, therefore, demonstrate involvement of CDC25B and MDM2 overexpression in radiation-induced tumorigenesis and provide novel targets for detection of radiation-induced carcinogenesis.

  20. How much do we know about spontaneous human mutation rates

    Energy Technology Data Exchange (ETDEWEB)

    Crow, J.F. (Univ. of Wisconsin, Madison, WI (United States))

    1993-01-01

    The much larger number of cell divisions between zygote and sperm than between zygote and egg, the increased age of fathers of children with new dominant mutations, and the greater evolution rate of pseudogenes on the Y chromosome than of those on autosomes all point to a much higher mutation rate in human males than in females, as first pointed out by Haldane in his classical study of X-linked hemophilia. The age of the father is the main factor determining the human spontaneous mutation rate, and probably the total mutation rate. The total mutation rate in Drosophila males of genes causing minor reduction in viability is at least 0.4 per sperm and may be considerably higher. The great mutation load implied by a rate of [approx] 1 per zygote can be greatly ameliorated by quasi-transition selection. Corresponding data are not available for the human population. The evolution rate of pseudogenes in primates suggests some 10[sup 2] new mutations per zygote. Presumably the overwhelming majority of these are neutral, but even the approximate fraction is not known. Statistical evidence in Drosophilia shows that mutations with minor effects cause about the same heterozygous impairment of fitness as those that are lethal when homozygous. The magnitude of heterozygous effect is such that almost all mutant genes are eliminated as heterozygotes before ever becoming homozygous. Although quantitative data in the human species are lacking, anecdotal information supports the conclusion that partial dominance is the rule here as well. This suggests that if the human mutation rate were increased or decreased, the effects would be spread over a period of 50-100 generations. 31 refs., 3 figs., 2 tabs.

  1. Jatropha curcas improvement Induced mutation: Thies University Senegal

    International Nuclear Information System (INIS)

    Diédhiou, Ibrahima

    2011-06-01

    The objectives are: 1. to collect accessions of Jatropha curcas in Senegal and establish the genetic variability of this collection. 2. to improve the oil yield of Jatropha curcas by using radiation induced mutation methods to produce highly productive genotypes adapted to local conditions. The choice of Jatropha Curcas is explained by: * Intensive cultivation of Jatropha curcas initiated in many countries of West Africa to produce biodiesel. *There is a craze of private companies to promote this new agricultural value chain. * Jobs and substantial revenues are expected for the rural. *Unfortunately, there is little reliable knowledge to support this dynamic development. Also, the preliminary results showed a high variability of agro-morphological traits in local accessions which could affect negatively the profitability.

  2. Mutation Rates of STR Systems in Danes

    DEFF Research Database (Denmark)

    Andersen, Kim Emil; Bøttcher, Susanne Gammelgaard; Christensen, Susanne

    Danish paternity cases in the period 1999 to 2005 were investigated regarding mutation rates in STR loci. STR-typing was performed by the Applied Biosystems AmplfStr Profiler Plus kit in the period 1999 to early 2005, hereafter named the PP9, and by Applied Biosystems AmplfStr Identifier kit for ...... and kits. Sex and STR locus specific mutation rates were estimated with 95% confidence limits by the method of Clopper and Pearson (1934)....

  3. Induced mutation for the improvement of soybean (Glycine max L.)

    International Nuclear Information System (INIS)

    Asencion, A.B.; Lapade, A.G.; Grafia, A.O.; Barrida, A.C.; Veluz, A.M.; Marbella, L.J.

    2004-01-01

    A study on the use of gamma radiation in the induction of mutations in eight varieties of soybean was conducted. The radiosensitivity of the seeds of both local and introduced soybean varieties was determined. The effects of gamma radiation in the M1 generation were evaluated. Percentage germination was not affected by doses of 200 and 250 Gy gamma radiation in all the eight soybean varieties. No significant differences in seedling height were observed at 200 Gy and the control except for the 250 Gy in BPI-Sy4, PSB-Sy4 and PSB-Sy5. In the Vietnamese varieties, significant differences in seedling height were obtained in doses of 200, 250 Gy and the control except for the variety AKO 6. There was significant difference in plant height of mature plants between the control and treatment dose of 250 Gy in varieties DT 95 and AKO 6. Likewise, significant differences in mature plant height were noted between the control and those at 250 Gy in local varieties BPI-Sy4, PSB-Sy5 and NSIC-Sy8. The number of days to flower was not affected by gamma radiation in both the local and introduced varieties. There were significant differences in the number of pods per plant between the control and a low dose of 200 Gy in Vietnamese variety DT 96 and the local varieties PSB-Sy4, PSB-Sy5 and NSIC-Sy8. The 3 types of chlorophyll mutation induced by gamma rays in the local varieties were: chlorina, striatia,and spotted yellow. Only chlorina mutant was induced in the introduced varieties. Desirable mutants that are early and high yielding were selected. Results of the drought tolerance tests indicated that the number of days to flowering of the control and 8 varieties was not affected by the duration of irrigation withdrawals 20,30,40 and 50 days after planting. Significant differences in seed weight among the different varieties were noted only in 20 and 30 day irrigation withdrawal treatment. When the effects of the different treatments were analyzed on a per variety bases, some of the

  4. The study of human mutation rates

    International Nuclear Information System (INIS)

    Neel, J.V.

    1992-01-01

    We will describe recent developments regarding the question of induced mutations in the survivors of the atomic bombings of Hiroshima and Nagasaki. As part of that work we, describe some developments with respect to the Amerindian blood samples collected under DoE sponsorship between 1964 and 1982. Then developments regarding the application of two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) to the study of genetic variation and mutation affecting protein characteristics. In particular, we will report on the identification and isolation of genes of especial interest as reflected in the behavior of the proteins which they encode

  5. DNA sequence analysis of spontaneous and γ-radiation (anoxic)-induced lacId mutations in Escherichia coli umuC122::Tn5: Differential requirement for umuC at G·C vs. A·T sites and for the production of transversions vs. transitions

    International Nuclear Information System (INIS)

    Sargentini, Neil J.; Smith, Kendric C.

    1994-01-01

    Escherichia coli umuC122::Tn5 cells were γ-irradiated ( 137 Cs, 750 Gy, under N 2 ), and lac-constitutive mutants were produced at 36% of the wild-type level. The specific nature of the umuC strain's partial radiation mutability was determined by sequencing 325 radiation-induced lacI d mutations. The yields of radiation-induced mutation classes in the umuC strain (as a percentage of the wild-type yield) were: 80% for A·T approaches G·C transitions, 70% for multi-base additions, 60% for single-base deletions, 53% for A·T approaches C·G transversions, 36% for G·C approaches A·T transitions, 25% for multi-base deletions, 21% for A·T approaches T·A transversions, 11% for G·C approaches C·G transversions, 9% for G·C approaches T·A transversions, and 0% for multiple mutations. Based on these deficiencies and other factors, it is concluded that the umuC strain is near-normal for A·T approaches G·C transitions, single-base deletions and possibly A·T approaches C·G transversions; is generally deficient for mutagenesis at G·C sites and for transversions, and is grossly deficient in multiple mutations. Damage at G·C sites seems more difficult for translesion DNA synthesis to bypass than damage at A·T sites, and especially when trying to produce a transversion. The yield of G·C approaches A·T transitions in the umuC strain (36% of the wild-type level) argues that abasic sites are involved in no more than 64% of γ-radiation-induced base substitutions in the wild-type strain. Altogether, these data suggest that the UmuC and UmuD' proteins facilitate, rather than being absolutely required for, translesion DNA synthesis; with the degree of facilitation being dependent both on the nature of the non-coding DNA damage, i.e., at G·C vs. A·T sites, and on the nature of the mis-incorporated base, i.e., whether it induces transversions or transitions

  6. Mutational spectrum analysis of umuC-independent and umuC-dependent γ-radiation mutagenesis in Escherichia coli

    International Nuclear Information System (INIS)

    Sargentini, N.J.; Smith, K.C.

    1989-01-01

    γ-radiation mutagenesis Escherichia coli K-12. Mutagenesis (argE3(OC) A rg + ) was blocked in a δ(recA-srlR)306 strain at the same doses that induced mutations in umuC122::Tn5 and wild-type strains, indicating that both umuC-independent and umuC-dependent mechanisms function within recA-dependent misrepair. Analyses of various suppressor and back mutations that result in argE3 and hisG4 ochre reversion and an analysis of trpE9777 reversion were performed on umuC and wild-type cells irradiated in the presence and absence of oxygen. While the umuC strain showed the γ-radiation induction of base substitution and frameshifts when irradiated in the absence of oxygen, the umuC mutation blocked all oxygen-dependent base-substitution mutagenesis, but non all oxygen-dependent frameshift mutagenesis. For anoxically irradiated cells, the yields of GC T and AT GC transitions were essentially umuC independent, while the yields of (AT or GC) TA transversions were heavily umuC dependent. These data suggest new concepts about the nature of the DNA lesions and the mutagenic mechanisms that lead to γ-radiation mutagenesis. (author). 48 refs.; 1 tab.; 6 refs

  7. The use of radiations to induce useful mutations in fruit trees

    International Nuclear Information System (INIS)

    Donini, B.

    1976-01-01

    The researches carried out at Casaccia in this field had covered the problems of technique of mutagenic treatment, mechanism of mutation induction and methodology of somatic mutation isolation. To enhance the efficiency of somatic mutation induction several conditions during and after the treatment have been studied. More experience has been gained with regard to the induction of somatic mutation which raises from genetical event or by tissue arrangement of a chimaeric shoot apex. To increase the size of mutated sector treatment have been carried out on the primordia in a very early stages and to improve the methodology of somatic mutation special techniques have been adapted of handling the material in the propagation. Possibility for early detection of mutants has been explored in cherry by establishing a correlation between mutants and hormonal content. By using the above mentioned techniques, useful mutants have been isolated in cherries, grapes, olives and peaches. (author)

  8. Induced mutations for crop improvement- the generation next

    International Nuclear Information System (INIS)

    Bhatia, C.R.

    2000-01-01

    Experiments to use induced mutations for the improvement of crop plants were initiated in the country in mid nineteen fifties. After forty five years and reasonably good success stories, it is no longer an attractive subject for bright young graduate students. The areas of intellectually satisfying, contemporary, plant genetics based on induced mutations that can also bring social and commercial benefits are identified. These are: nodulation mutants in legumes, altering fatty acid composition in oil crops, modification of root characters, altering host-pathogen interactions, flowering time, day length insensitivity and some changes in modulation pattern involve mutations

  9. DNA sequence analysis of X-ray induced Adh null mutations in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Mahmoud, J.; Fossett, N.G.; Arbour-Reily, P.; McDaniel, M.; Tucker, A.; Chang, S.H.; Lee, W.R.

    1991-01-01

    The mutational spectrum for 28 X-ray induced mutations and 2 spontaneous mutations, previously determined by genetic and cytogenetic methods, consisted of 20 multilocus deficiencies (19 induced and 1 spontaneous) and 10 intragenic mutations (9 induced and 1 spontaneous). One of the X-ray induced intragenic mutations was lost, and another was determined to be a recombinant with the allele used in the recovery scheme. The DNA sequence of two X-ray induced intragenic mutations has been published. This paper reports the results of DNA sequence analysis of the remaining intragenic mutations and a summary of the X-ray induced mutational spectrum. The combination of DNA sequence analysis with genetic complementation analysis shows a continuous distribution in size of deletions rather than two different types of mutations consisting of deletions and 'point mutations'. Sequencing is shown to be essential for detecting intragenic deletions. Of particular importance for future studies is the observation that all of the intragenic deletions consist of a direct repeat adjacent to the breakpoint with one of the repeats deleted

  10. Whole genome sequencing of mutation accumulation lines reveals a low mutation rate in the social amoeba Dictyostelium discoideum.

    Directory of Open Access Journals (Sweden)

    Gerda Saxer

    Full Text Available Spontaneous mutations play a central role in evolution. Despite their importance, mutation rates are some of the most elusive parameters to measure in evolutionary biology. The combination of mutation accumulation (MA experiments and whole-genome sequencing now makes it possible to estimate mutation rates by directly observing new mutations at the molecular level across the whole genome. We performed an MA experiment with the social amoeba Dictyostelium discoideum and sequenced the genomes of three randomly chosen lines using high-throughput sequencing to estimate the spontaneous mutation rate in this model organism. The mitochondrial mutation rate of 6.76×10(-9, with a Poisson confidence interval of 4.1×10(-9 - 9.5×10(-9, per nucleotide per generation is slightly lower than estimates for other taxa. The mutation rate estimate for the nuclear DNA of 2.9×10(-11, with a Poisson confidence interval ranging from 7.4×10(-13 to 1.6×10(-10, is the lowest reported for any eukaryote. These results are consistent with low microsatellite mutation rates previously observed in D. discoideum and low levels of genetic variation observed in wild D. discoideum populations. In addition, D. discoideum has been shown to be quite resistant to DNA damage, which suggests an efficient DNA-repair mechanism that could be an adaptation to life in soil and frequent exposure to intracellular and extracellular mutagenic compounds. The social aspect of the life cycle of D. discoideum and a large portion of the genome under relaxed selection during vegetative growth could also select for a low mutation rate. This hypothesis is supported by a significantly lower mutation rate per cell division in multicellular eukaryotes compared with unicellular eukaryotes.

  11. Induced Mutations in Thai Rice

    International Nuclear Information System (INIS)

    Klakhaeng, Kanchana

    2014-01-01

    Rice is the primary source of food for more than half of the world's population. It benefits greatly from technological inputs in the area of breeding such as induced mutation. Induced mutation can produce mutants with significant improvement in plant type, maturity, yields and protein ratio when compared to the parent. These improved traits enable the mutants to fit into farming systems with either shorter or longer growing seasons. Three induced mutant rice varieties, including RD6, RD10 and RD15, are well accepted by farmers and consumers in Thailand. RD6 and RD15 were aromatic, photosensitive varieties which were derived from KDML105 by acute irradiation of 20 and 15 kilorad gamma ray, respectively. After induced mutation, pedigree selection was applied. RD6 showed drought tolerance and also good grain quality including softness and good aroma with a higher average yield than the famous glutinous variety, San-Pah-Tong. Additionally, it was resistant to blast and brown spot diseases with an average yield of 4.19 tons/ha. RD15 showed drought tolerance and resistance to brown spot disease with the highest yield of 3.5 tons/ha. These two mutant varieties are currently the most famous aromatic rice varieties in Thailand. On the other hand, RD10 is a glutinous, photoperiod insensitive rice variety which was derived from RD1 by irradiation of 1 kilorad fast neutrons. RD10 showed good grain quality such as softness and stickiness with the yield of 4.25 tons/ha. As an on-going project, recommended rice varieties were irradiated with electron beam for anaerobic germination ability, submergence tolerance, stagnant-flood tolerance and also internode elongation.

  12. Radiation-induced ηe-modes

    International Nuclear Information System (INIS)

    Shukla, P.K.; Yu, M.Y.

    1990-01-01

    Impurity radiation in a plasma can cause not only static instabilities, but also dynamic instabilities related to the drift and acoustic waves. Radiative instabilities are of much interest because they are associated with relatively high frequency and short wavelength fluctuations, which have been suspected to be responsible for anomalous electron energy transport in tokamak edge plasmas. In this paper, we consider radiation-induced η e instabilities, taking into account electrostatic effects as well as density and temperature inhomogeneities. Also included are the effects of finite gyroradius and dissipation. It is found that the latter can cause strong linear coupling between the modes of interest. The resulting instabilities can have larger growth rates than the static radiative instability. Analytical expressions for the growth rates and instability regimes are given for the limiting cases of practical interest. In particular, it is shown that the η e -mode can couple to both radiation and dissipation to cause resistive instabilities. The parameter regimes of the original radiative as well as the dissipative modes are thereby broadened and shifted because of the interaction. (author) 3 refs

  13. Mutation induction by ion beams in arabidopsis

    International Nuclear Information System (INIS)

    Tanaka, Atsushi

    1999-01-01

    An investigation was made on characteristics of ion beams for the biological effects and the induction of mutation using Arabidopsis plant as a model plant for the molecular genetics. Here, the characteristics of mutation at the molecular level as well as new mutants induced by ion beams were described. The ast and sep1 were obtained from the offspring of 1488 carbon ion-irradiated seeds respectively. The uvi1-uvi4 mutants were also induced from 1280 M 1 lines. Thus, ion beams can induce not only known mutants such as tt, gl and hy but also novel mutants with high frequency. Even in the tt phenotype, two new mutant loci other than known loci were found. In chrysanthemum, several kinds of single, complex or stripped flower-color mutants that have been never induced by γirradiation, indicating that ion beams could produce a variety of mutants with the same phenotype. In conclusion, ion beams for the mutation induction are characterized by 1) to induce mutants with high frequency, 2) to show broad mutation spectrum and 3) to produce novel mutants. For these reasons, chemical mutagens such as EMS and low LET ionizing radiation such as X-rays and γ-rays will predominantly induce many but small modifications or DNA damages on the DNA strands. As the result, several point mutations will be produced on the genome. On the contrary, ion beams as a high LET ionizing radiation will not cause so many but large and irreparable DNA damage locally, resulting in production of limited number of null mutation. (M.N.)

  14. Mutation induction by ion beams in arabidopsis

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Atsushi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1999-07-01

    An investigation was made on characteristics of ion beams for the biological effects and the induction of mutation using Arabidopsis plant as a model plant for the molecular genetics. Here, the characteristics of mutation at the molecular level as well as new mutants induced by ion beams were described. The ast and sep1 were obtained from the offspring of 1488 carbon ion-irradiated seeds respectively. The uvi1-uvi4 mutants were also induced from 1280 M{sub 1} lines. Thus, ion beams can induce not only known mutants such as tt, gl and hy but also novel mutants with high frequency. Even in the tt phenotype, two new mutant loci other than known loci were found. In chrysanthemum, several kinds of single, complex or stripped flower-color mutants that have been never induced by {gamma}irradiation, indicating that ion beams could produce a variety of mutants with the same phenotype. In conclusion, ion beams for the mutation induction are characterized by 1) to induce mutants with high frequency, 2) to show broad mutation spectrum and 3) to produce novel mutants. For these reasons, chemical mutagens such as EMS and low LET ionizing radiation such as X-rays and {gamma}-rays will predominantly induce many but small modifications or DNA damages on the DNA strands. As the result, several point mutations will be produced on the genome. On the contrary, ion beams as a high LET ionizing radiation will not cause so many but large and irreparable DNA damage locally, resulting in production of limited number of null mutation. (M.N.)

  15. Specificity of mutations induced by carbon ions in budding yeast Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Matuo, Youichirou; Nishijima, Shigehiro; Hase, Yoshihiro; Sakamoto, Ayako; Tanaka, Atsushi; Shimizu, Kikuo

    2006-01-01

    To investigate the nature of mutations induced by accelerated ions in eukaryotic cells, the effects of carbon-ion irradiation were compared with those of γ-ray irradiation in the budding yeast Saccharomyces cerevisiae. The mutational effect and specificity of carbon-ion beams were studied in the URA3 gene of the yeast. Our experiments showed that the carbon ions generated more than 10 times the number of mutations induced by γ-rays, and that the types of base changes induced by carbon ions include transversions (68.7%), transitions (13.7%) and deletions/insertions (17.6%). The transversions were mainly G:C → T:A, and all the transitions were G:C → A:T. In comparison with the surrounding sequence context of mutational base sites, the C residues in the 5'-AC(A/T)-3' sequence were found to be easily changed. Large deletions and duplications were not observed, whereas ion-induced mutations in Arabidopsis thaliana were mainly short deletions and rearrangements. The remarkable feature of yeast mutations induced by carbon ions was that the mutation sites were localized near the linker regions of nucleosomes, whereas mutations induced by γ-ray irradiation were located uniformly throughout the gene

  16. Evolutionary rescue of a parasite population by mutation rate evolution.

    Science.gov (United States)

    Greenspoon, Philip B; Mideo, Nicole

    2017-10-01

    The risk of antibiotic resistance evolution in parasites is a major problem for public health. Identifying factors which promote antibiotic resistance evolution is thus a priority in evolutionary medicine. The rate at which new mutations enter the parasite population is one important predictor; however, mutation rate is not necessarily a fixed quantity, as is often assumed, but can itself evolve. Here we explore the possible impacts of mutation rate evolution on the fate of a disease circulating in a host population, which is being treated with drugs, the use of which varies over time. Using an evolutionary rescue framework, we find that mutation rate evolution provides a dramatic increase in the probability that a parasite population survives treatment in only a limited region, while providing little or no advantage in other regions. Both epidemiological features, such as the virulence of infection, and population genetic parameters, such as recombination rate, play important roles in determining the probability of evolutionary rescue and whether mutation rate evolution enhances the probability of evolutionary rescue or not. While efforts to curtail mutation rate evolution in parasites may be worthwhile under some circumstances, our results suggest that this need not always be the case. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Interaction of alpha radiation with thermally-induced defects in silicon

    International Nuclear Information System (INIS)

    Ali, Akbar; Majid, Abdul

    2008-01-01

    The interaction of radiation-induced defects created by energetic alpha particles and thermally-induced defects in silicon has been studied using a Deep Level Transient Spectroscopy (DLTS) technique. Two thermally-induced defects at energy positions E c -0.48 eV and E c -0.25 eV and three radiation-induced defects E2, E3 and E5 have been observed. The concentration of both of the thermally-induced defects has been observed to increase on irradiation. It has been noted that production rates of the radiation-induced defects are suppressed in the presence of thermally-induced defects. A significant difference in annealing characteristics of thermally-induced defects in the presence of radiation-induced defects has been observed compared to the characteristics measured in pre-irradiated samples

  18. Microdosimetrical calculations of the rate of repairable DNA - double strand breaks based on a model for the interpretation of experiments with different doses and radiation qualities

    International Nuclear Information System (INIS)

    Rosemann, M.; Regel, K.

    1990-01-01

    When comparing various DNA injuries induced by radiation double breaks were shown to play peculiar role in subsequent cell changes such as inactivation, aberrations, mutations and transformations. However it was proved that significant part of radiation-induced double breaks could be repaied within cell. 3 refs

  19. Effect of durable γ-radiation on E.Coli

    International Nuclear Information System (INIS)

    Koudela, K.; Drashil, V.

    1990-01-01

    Effect of prolonged low intensity γ-radiation on changes of frequency of reversion mutations was studied in Escherichia Coli. Frequency of His + revertants was shown to depend on growth phase. Cellular DNA absorbed more energy in stationary than DNA in growth phase. K-12 AB2497 strain of Escherichia Coli D-37 comprised about 60 Gy. This dose wasn't absorbed under continuous irradiation at dose rate of 0.21 R/min in 5 hours. The dose rate was considered to be sufficient to induce SOS-system and thus to increase mutations number. 2 refs

  20. Mutation breeding newsletter. No. 43

    International Nuclear Information System (INIS)

    1997-10-01

    This issue of the Newsletter includes articles dealing with radiation induced mutation based plant breeding research findings aimed at improving productivity, disease resistance and tolerance of stress conditions

  1. Biological research for radiation protection

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Gyu; Kim, Kug Chan; Shim, Hae Won; Oh, Tae Jeong; Park, Seon Young; Lee, Kang Suk

    2000-04-01

    The work scope of Biological research for the radiation protection had contained the search of biological microanalytic methods for assessing the health effect by {gamma}-radiation and toxic agents, the standardization of human T-lymphocyte cell culture and polymerase chain reaction, T-cell clonal assay, and the quantification of mutation frequency in the hypoxanthine (guanine) phosphoribosyl transferase (HPRT) gene locus by single exposure or combined exposure. Especially, the polymerase chain reaction methods using reverse transcriptase has been developed to analyze the mutant gene induced by {gamma}-radiation and chemical (pentachlorophenol) agent exposure, and to investigate the point mutations in the HPRT gene locus of T-lymphocytes. The HPRT T-cell clonal assay revealed that it could not differentiate {gamma}-irradiation from pentachlorophenol, because the frequency of somatic mutations induced by both damaging agents increased in a dose-dependent manner. The analysis of DNA sequence alterations of HPRT mutant clones clearly showed that both damaging agents induced different mutational spectra in the HPRT locus of T-cells. The large deletions, which account for 75 percent of the analyzed mutants, are characteristic mutations induced by {gamma}-irradiation. By contrast, point mutations such as base substitutions and insertion, come up to 97 percent in the case of pentachlorophenol-treated cells. The point mutation frequencies at 190 base pair and 444 base pair positions are 3-6 folds as high as in those at other mutation positions. It may be that these mutation sites are hot spots induced by pentachlorophenol. These results suggest that the HPRT mutation spectrum can be used as a potential bio marker for assessing a specific environmental risk. (author)

  2. Biological research for radiation protection

    International Nuclear Information System (INIS)

    Kim, In Gyu; Kim, Kug Chan; Shim, Hae Won; Oh, Tae Jeong; Park, Seon Young; Lee, Kang Suk

    2000-04-01

    The work scope of Biological research for the radiation protection had contained the search of biological microanalytic methods for assessing the health effect by γ-radiation and toxic agents, the standardization of human T-lymphocyte cell culture and polymerase chain reaction, T-cell clonal assay, and the quantification of mutation frequency in the hypoxanthine (guanine) phosphoribosyl transferase (HPRT) gene locus by single exposure or combined exposure. Especially, the polymerase chain reaction methods using reverse transcriptase has been developed to analyze the mutant gene induced by γ-radiation and chemical (pentachlorophenol) agent exposure, and to investigate the point mutations in the HPRT gene locus of T-lymphocytes. The HPRT T-cell clonal assay revealed that it could not differentiate γ-irradiation from pentachlorophenol, because the frequency of somatic mutations induced by both damaging agents increased in a dose-dependent manner. The analysis of DNA sequence alterations of HPRT mutant clones clearly showed that both damaging agents induced different mutational spectra in the HPRT locus of T-cells. The large deletions, which account for 75 percent of the analyzed mutants, are characteristic mutations induced by γ-irradiation. By contrast, point mutations such as base substitutions and insertion, come up to 97 percent in the case of pentachlorophenol-treated cells. The point mutation frequencies at 190 base pair and 444 base pair positions are 3-6 folds as high as in those at other mutation positions. It may be that these mutation sites are hot spots induced by pentachlorophenol. These results suggest that the HPRT mutation spectrum can be used as a potential bio marker for assessing a specific environmental risk. (author)

  3. In utero exposure to nanosized carbon black (Printex90) does not induce tandem repeat mutations in female murine germ cells

    DEFF Research Database (Denmark)

    Boisen, Anne Mette Zenner; Shipley, Thomas; Jackson, Petra

    2013-01-01

    Inhalation of particles has been shown to induce mutations in the male germline in mice following both prenatal and adult exposures in several experiments. In contrast, the effects of particles on female germ cell mutagenesis are not well established. Germline mutations are induced during active...... cell division, which occurs during fetal development in females. We investigated the effects of prenatal exposure to carbon black nanoparticles (CB) on induction of mutations in the female mouse germline during fetal development, spanning the critical developmental stages of oogenesis. Pregnant C57BL/6...... mutation rates in the resulting F2 generation were determined from full pedigrees (mother, father, offspring) of F1 female mice (178 CB-exposed and 258 control F2 offspring). ESTR mutation rates in CB-exposed F2 female offspring were not statistically different from those of F2 female control offspring....

  4. Genetic topics in radiation protection

    Energy Technology Data Exchange (ETDEWEB)

    Traut, H [Muenster Univ. (F.R. Germany). Inst. fuer Strahlenbiologie

    1976-01-01

    The effects of mutations induced by ionizing radiation on human health can be subdivided into decrease of general viability, malformations and embryonic death. Reasons are given for the recommendation why a man whose gonads had been exposed to radiation should refrain from procreation for a couple of months. An analysis of the frequency of chromosome aberrations induced in lymphocytes can provide an estimate of the dose received during an accidental exposure. Radiation induced chronic myeloid leukaemia is probably based on the induction of an aberration involving chromosome 22 in a bone marrow cell (deletion, translocation). The relationship between the frequency of radiation induced point mutations and the DNA content of the genome of the species studied so far is discussed.

  5. Mutation studies on garden roses: a review

    International Nuclear Information System (INIS)

    Datta, S.K.

    1997-01-01

    Most of the modern roses are the result of hybridization, selection and spontaneous mutation. For floriculture trade, there is always demand and necessity for new varieties due to change in taste and fashion. Mutation breeding is an established method for crop improvement. Induced somatic mutation breeding holds promise for effective improvement and have high potential for bringing about genetic improvement and it has led to a great burst of flower colour, form, pattern and other variations in rose by using ionizing radiations. The details of prospects and utilization of induced mutation breeding technique for developing new rose varieties have been compiled. (author)

  6. Genetic analysis of radiation-induced mouse thymic lymphomas

    International Nuclear Information System (INIS)

    Kominami, R.; Wakabayashi, Y.; Niwa, O.

    2003-01-01

    Mouse thymic lymphomas are one of the classic models of radiation-induced malignancies, and the model has been used for the study of genes involved in carcinogenesis. ras oncogenes are the first isolate which undergoes mutations in 10 to 30 % of lymphomas, and p16INK4a and p19ARF in the INK4a-ARF locus are also frequently inactivated. In our previous study, the inactivation of Ikaros, a key regurator of lymphoid system, was found in those lymphomas, and it was suggested that there are other responsible genes yet to be discovered. On the other hand, genetic predisposition to radiation-induced lymphoma often differs in different strains, and this reflects the presence of low penetrance genes that can modify the impact of a given mutation. Little study of such modifiers or susceptibility genes has been performed, either. Recent availability of databases on mouse genome information and the power of mouse genetic system underline usefulness of the lymphoma model in search for novel genes involved, which may provide clues to molecular mechanisms of development of the radiogenic lymphoma and also genes involved in human lymphomas and other malignancies. Accordingly, we have carried out positional cloning for the two different types of tumor-related genes. In this symposium, our current progress is presented that includes genetic mapping of susceptibility/ resistance loci on mouse chromosomes 4, 5 and 19, and also functional analysis of a novel tumor suppressor gene, Rit1/Bcl11b, that has been isolated from allelic loss (LOH) mapping and sequence analysis for γ -ray induced mouse thymic lymphomas

  7. Radiation-induced apoptosis

    International Nuclear Information System (INIS)

    Ohyama, Harumi

    1995-01-01

    Apoptosis is an active process of gene-directed cellular self-destruction that can be induced in many cell types via numerous physiological and pathological stimuli. We found that interphasedeath of thymocytes is a typical apoptosis showing the characteristic features of apoptosis including cell shrinkage, chromatin condensation and DNA degradation. Moderate dose of radiation induces extensive apoptosis in rapidly proliferating cell population such as the epithelium of intestinal crypt. Recent reports indicate that the ultimate form of radiation-induced mitotic death in several cells is also apoptosis. One of the hallmarks of apoptosis is the enzymatic internucleosomal degradation of chromatin DNA. We identified an endonuclease responsible for the radiation-induced DNA degradation in rat thymocytes. The death-sparing effects of interrupting RNA and protein synthesis suggested a cell genetic program for apoptosis. Apoptosis of thymocytes initiated by DNA damage, such as radiation and radio mimetic substance, absolutely requires the protein of p53 cancer suppresser gene. The cell death induced by glucocorticoid, or aging, has no such requirement. Expression of oncogene bcl-2 rescues cells from the apoptosis. Massive apoptosis in radiosensitive cells induced by higher dose radiation may be fatal. It is suggested that selective apoptotic elimination of cells would play an important role for protection against carcinogenesis and malformation through removal of cells with unrepaired radiation-induced DNA damages. Data to evaluate the significance of apoptosis in the radiation risk are still poor. Further research should be done in order to clarify the roles of the cell death on the acute and late effects of irradiation. (author)

  8. Imaging Features that Discriminate between Foci Induced by High- and Low-LET Radiation in Human Fibroblasts

    International Nuclear Information System (INIS)

    Costes, Sylvain V.; Boissiere, Arnaud; Ravani, Shraddha; Romano, Raquel; Parvin, Bahram; Barcellos-Hoff, Mary Helen

    2006-01-01

    In this study, we investigated the formation of radiation-induced foci in normal human fibroblasts exposed to X rays or 130 keV/mum nitrogen ions using antibodies to phosphorylated protein kinase ataxia telangiectasia mutated (ATMp) and histone H2AX(gamma-H2AX). High-content automatic image analysis was used to quantify the immunofluorescence of radiation-induced foci. The size of radiation-induced foci increased for both proteins over a 2-h period after nitrogen-ion irradiation, while the size of radiation-induced foci did not change after exposure to low-LET radiation. The number of radiation-induced ATMp foci showed a more rapid rise and greater frequency after X-ray exposure and was resolved more rapidly such that the frequency of radiation-induced foci decreased by 90 percent compared to 60 percent after exposure to high-LET radiation 2 h after 30 cGy. In contrast, the kinetics of radiation-induced gamma-H2AX focus formation was similar for high- and low-LET radiation in that it reached a plateau early and remained constant for up to 2 h. High-resolution 3D images of radiation-induced gamma-H2AX foci and dosimetry computation suggest that multiple double-strand breaks from nitrogen ions are encompassed within large nuclear domains of 4.4 Mbp. Our work shows that the size and frequency of radiation-induced foci vary as a function of radiation quality, dose, time and protein target. Thus, even though double-strand breaks and radiation-induced foci are correlated, the dynamic nature of both contradicts their accepted equivalence for low doses of different radiation qualities

  9. Radiation-induced creep and swelling

    International Nuclear Information System (INIS)

    Heald, P.T.

    1977-01-01

    The physical basis for radiation induced creep and swelling is reviewed. The interactions between the point defects and dislocations are recalled since these interactions are ultimately responsible for the observable deformation phenomena. Both the size misfit interaction and the induced inhomogeneity interaction are considered since the former gives rise to irradiation swelling while the latter, which depends on both internal and external stresses, results in irradiation creep. The defect kinetics leading to the deformation processes are discussed in terms of chemical rate theory. The rate equations for the spatially averaged interstitial and vacancy concentrations are expressed in terms of the microstructural sink strengths and the solution of these equations leads to general expressions for the deformation rates

  10. Mutation breeding in malting barley

    Energy Technology Data Exchange (ETDEWEB)

    Hiraki, Makoto; Sanada, Matsuyoshi

    1984-03-01

    The released varieties of malting barley through mutation breeding is more than ten in number, including foreign varieties. In Japan four varieties has been released so far. We started mutation breeding in 1956 together with cross breeding that we employed before. Until now, Gamma 4, Amagi Nijo 1 and Fuji Nijo 2 have been produced from the direct use of induced mutations and Nirasaki Nijo 8 from the indirect use of them. Mutation breeding has been used mainly in the partial improvement of agronomic characteristics since the selection for malting quality was very complicated. As the variety bred by induced mutation is usually equivalent to the original variety in malting quality, both this new variety and the original one could be cultivated in the same area without any problem on later malt production. Particularly when one farmer cultivates barley in an extensive acreage, he can harvest at the best time according to the different maturing time of each variety. From these points of view, mutation breeding is an efficient tool in malting barley breeding. Mutagens we have used so far are X-rays, ..gamma..-rays, neutron and chemicals such as dES. From our experience in selection, the low dose of radiation and chemical mutagens are more effective in selection of point mutation than the high dose of radiation which tends to produce many abnormal but few practical mutants. (author).

  11. Most ultraviolet irradiation induced mutations in the nematode Caenorhabditis elegans are chromosomal rearrangements

    International Nuclear Information System (INIS)

    Stewart, H.I.; Rosenbluth, R.E.; Baillie, D.L.

    1991-01-01

    In this study the utility of 254-nm ultraviolet light (UV) as a magnetic tool in C.elegans is determined. It is demonstrated that irradiation of adult hermaphrodites provides a simple method for the induction of heritable chromosomal rearrangements. A screening protocol was employed that identifies either recessive lethal mutations in the 40 map unit region balanced by the translocation eT1(III;V), or unc-36(III) duplications. Mutations were recovered in 3% of the chromosomes screened after a dose of 120 J/m 2 . This rate resembles that for 1500 R γ-ray-induced mutations selected in a similar manner. The mutations were classified either as lethals [mapping to Linkage Group (LG)III or LGV] or as putative unc-36 duplications. In contrast to the majority of UV-induced mutations analysed in micro-organisms, a large fraction of the C.elegans UV-induced mutations were found to be not simple intragenic lesions, but deficiencies for more than one adjacent gene or more complex events. Preliminary evidence for this conclusion came from the high frequency of mutations that had a dominant effect causing reduced numbers of adult progeny. Subsequently 6 out of 9 analysed LGV mutations were found to be deficiencies. Other specific rearrangements also identified were: one translocation, sT5(II;III), and two unc-36 duplications, sDp8 and sDp9. It was concluded that UV irradiation can easily be used as an additional tool for the analysis of C.elegans chromosomes, and that C.elegans should prove to be a useful organism in which to study the mechanisms whereby UV acts as a mutagen in cells of complex eukaryotes. (author). 46 refs.; 5 figs.; 4 tabs

  12. Dependence of Early and Late Chromosomal Aberrations on Radiation Quality and Cell Types

    Science.gov (United States)

    Lu, Tao; Zhang, Ye; Krieger, Stephanie; Yeshitla, Samrawit; Goss, Rosalin; Bowler, Deborah; Kadhim, Munira; Wilson, Bobby; Rohde, Larry; Wu, Honglu

    2017-01-01

    Exposure to radiation induces different types of DNA damage, increases mutation and chromosome aberration rates, and increases cellular transformation in vitro and in vivo. The susceptibility of cells to radiation depends on genetic background and growth condition of cells, as well as types of radiation. Mammalian cells of different tissue types and with different genetic background are known to have different survival rate and different mutation rate after cytogenetic insults. Genomic instability, induced by various genetic, metabolic, and environmental factors including radiation, is the driving force of tumorigenesis. Accurate measurements of the relative biological effectiveness (RBE) is important for estimating radiation-related risks. To further understand genomic instability induced by charged particles and their RBE, we exposed human lymphocytes ex vivo, human fibroblast AG1522, human mammary epithelial cells (CH184B5F5/M10), and bone marrow cells isolated from CBA/CaH(CBA) and C57BL/6 (C57) mice to high energy protons and Fe ions. Normal human fibroblasts AG1522 have apparently normal DNA damage response and repair mechanisms, while mammary epithelial cells (M10) are deficient in the repair of DNA DSBs. Mouse strain CBA is radio-sensitive while C57 is radio-resistant. Metaphase chromosomes at different cell divisions after radiation exposure were collected and chromosome aberrations were analyzed as RBE for different cell lines exposed to different radiations at various time points up to one month post irradiation.

  13. Specificity of mutations induced by carbon ions in budding yeast Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Matuo, Youichirou [Graduate School of Engineering, Osaka University, Yamada-oka 2-1, Suita, Osaka 565-0871 (Japan); Nishijima, Shigehiro [Graduate School of Engineering, Osaka University, Yamada-oka 2-1, Suita, Osaka 565-0871 (Japan); Hase, Yoshihiro [Radiation-Applied Biology Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), Watanuki-machi 1233, Takasaki, Gunma 370-1292 (Japan); Sakamoto, Ayako [Radiation-Applied Biology Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), Watanuki-machi 1233, Takasaki, Gunma 370-1292 (Japan); Tanaka, Atsushi [Radiation-Applied Biology Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), Watanuki-machi 1233, Takasaki, Gunma 370-1292 (Japan); Shimizu, Kikuo [Radioisotope Research Center, Osaka University, Yamada-oka 2-4, Suita, Osaka 565-0871 (Japan)]. E-mail: shimizu@rirc.osaka-u.ac.jp

    2006-12-01

    To investigate the nature of mutations induced by accelerated ions in eukaryotic cells, the effects of carbon-ion irradiation were compared with those of {gamma}-ray irradiation in the budding yeast Saccharomyces cerevisiae. The mutational effect and specificity of carbon-ion beams were studied in the URA3 gene of the yeast. Our experiments showed that the carbon ions generated more than 10 times the number of mutations induced by {gamma}-rays, and that the types of base changes induced by carbon ions include transversions (68.7%), transitions (13.7%) and deletions/insertions (17.6%). The transversions were mainly G:C {sup {yields}} T:A, and all the transitions were G:C {sup {yields}} A:T. In comparison with the surrounding sequence context of mutational base sites, the C residues in the 5'-AC(A/T)-3' sequence were found to be easily changed. Large deletions and duplications were not observed, whereas ion-induced mutations in Arabidopsis thaliana were mainly short deletions and rearrangements. The remarkable feature of yeast mutations induced by carbon ions was that the mutation sites were localized near the linker regions of nucleosomes, whereas mutations induced by {gamma}-ray irradiation were located uniformly throughout the gene.

  14. Radiation-induced void swelling in metals and alloys

    International Nuclear Information System (INIS)

    Zelinskij, V.F.; Neklyudov, I.M.; Ozhigov, L.S.; Reznichenko, Eh.A.; Rozhkov, V.V.; Chernyaeva, T.T.

    1979-01-01

    Main regularities in the development of radiation-induced void swelling are considered. Special attention is paid to consideration of a possibility to obtain information on material behaviour under conditions of reactor irradiation proceeding from the data of simulation experiments and to methods of rate control, for the processes which occur in material during irradiation and further annealing by the way of rationalized alloying, of thermomechanical treatment and programmed change of irradiation conditions under operation. Problems of initiation and growth of voids in irradiated materials are discussed as well as the ways to decrease the rate of radiation-induced void swelling

  15. Mutation breeding newsletter. No. 20

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1982-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  16. Mutation breeding newsletter. No. 17

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1981-03-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  17. Mutation breeding newsletter. No. 16

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1980-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  18. Mutation breeding newsletter. No. 8

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1976-09-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  19. Mutation breeding newsletter. No. 12

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1978-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  20. Mutation breeding newsletter. No. 10

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1977-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  1. Mutation breeding newsletter. No. 32

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1988-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  2. Mutation breeding newsletter. No. 18

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1981-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  3. Mutation breeding newsletter. No. 9

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1977-01-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  4. Mutation breeding newsletter. No. 22

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1983-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  5. Mutation breeding newsletter. No. 15

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1980-02-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  6. Mutation breeding newsletter. No. 9

    International Nuclear Information System (INIS)

    1977-01-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  7. Mutation breeding newsletter. No. 32

    International Nuclear Information System (INIS)

    1988-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  8. Mutation breeding newsletter. No. 15

    International Nuclear Information System (INIS)

    1980-02-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  9. Mutation breeding newsletter. No. 14

    International Nuclear Information System (INIS)

    1979-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  10. Mutation breeding newsletter. No. 16

    International Nuclear Information System (INIS)

    1980-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  11. Mutation breeding newsletter. No. 12

    International Nuclear Information System (INIS)

    1978-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  12. Mutation breeding newsletter. No. 17

    International Nuclear Information System (INIS)

    1981-03-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  13. Mutation breeding newsletter. No. 30

    International Nuclear Information System (INIS)

    1987-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  14. Mutation breeding newsletter. No. 18

    International Nuclear Information System (INIS)

    1981-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  15. Mutation breeding newsletter. No. 10

    International Nuclear Information System (INIS)

    1977-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  16. Mutation breeding newsletter. No. 8

    International Nuclear Information System (INIS)

    1976-09-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  17. Mutation breeding newsletter. No. 11

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1978-02-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  18. Mutation breeding newsletter. No. 31

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1988-03-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  19. Mutation breeding newsletter. No. 31

    International Nuclear Information System (INIS)

    1988-03-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  20. Mutation breeding newsletter. No. 11

    International Nuclear Information System (INIS)

    1978-02-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  1. Mutation breeding newsletter. No. 20

    International Nuclear Information System (INIS)

    1982-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  2. Mutation breeding newsletter. No. 19

    International Nuclear Information System (INIS)

    1982-01-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  3. Mutation breeding newsletter. No. 13

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1979-02-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  4. Mutation breeding newsletter. No. 30

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1987-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  5. Mutation breeding newsletter. No. 19

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1982-01-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  6. Mutation breeding newsletter. No. 23

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1983-01-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  7. Mutation breeding newsletter. No. 14

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1979-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  8. Mutation breeding newsletter. No. 23

    International Nuclear Information System (INIS)

    1983-01-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  9. Mutation breeding newsletter. No. 13

    International Nuclear Information System (INIS)

    1979-02-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  10. Mutation breeding newsletter. No. 22

    International Nuclear Information System (INIS)

    1983-07-01

    This issue of the Newsletter presents new reports on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  11. Mutation induced with ion beam irradiation in rose

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, H. E-mail: yhiroya@nias.affrc.go.jp; Nagatomi, S.; Morishita, T.; Degi, K.; Tanaka, A.; Shikazono, N.; Hase, Y

    2003-05-01

    The effects of mutation induction by ion beam irradiation on axillary buds in rose were investigated. Axillary buds were irradiated with carbon and helium ion beams, and the solid mutants emerged after irradiation by repeated cutting back. In helium ion irradiation, mutations were observed in plants derived from 9 buds among 56 irradiated buds in 'Orange Rosamini' and in plants derived from 10 buds among 61 irradiated buds in 'Red Minimo'. In carbon ion, mutations were observed in plants derived from 12 buds among 88 irradiated buds in 'Orange Rosamini'. Mutations were induced not only in higher doses but also in lower doses, with which physiological effect by irradiation was hardly observed. Irradiation with both ion beams induced mutants in the number of petals, in flower size, in flower shape and in flower color in each cultivar.

  12. Characteristics of commercially recommending sesame mutant cultivars through induced mutations by different sources of radiation and chemical in the Republic of Korea

    International Nuclear Information System (INIS)

    Kang, Churl Whan

    2001-01-01

    The sesame acreage in Korea has grown 2.5 times in the last two decades as the result of recommending sesame mutant cultivars and polyethylene mulch technique newly developed since 1978. The mutation was induced by X-ray irradiation at 200 Gy yielding a variety named 'Ahnsankkae' known for early ripeness, white color of seed coat, tolerance for diseases. 'Suwon 128' is a dwarf mutant bred through sodium azide and known for strong lodging resistance, dense and lower first capsule set and dense planting adaptability toward mechanized culture against typhoon. Seven mutant recommending cultivars of sesame are compared with respect to their qualitative and quantitative characteristics based on passport data regarding different mutagen sources of radiations and chemicals published by Committee New Recommending Cultivars on the Crops. Breeding sources are summarized: 5 out of 7 sources are through radiation (X-rays, γ-rays, and neutrons) and the rest 2 through chemicals. Their growth characteristics such as flowering date, maturing date, plant height, length-capsule bearing stem, disease and lodging resistance, oil content, and yield ability are also presented. (S. Ohno)

  13. The influence of glycerol on γ-induced mutagenesis in Salmonella typhimurium cells

    International Nuclear Information System (INIS)

    Basha, S.G.; Krasavin, E.A.; Kozubek, S.; Amirtaev, K.G.

    1990-01-01

    A study was made of the modifying effect of glycerol on the survival rate and γ-radiation-induced mutagenesis of Salmonella typhimurium cells TA98, TA100 and TA102. The DMF value, with respect to the survival rate, was 2.05-0.20. The dependence of the yield of γ-radiation-induced mutants on radiation dose was described by the curve with a maximum; the mutation frequency M(D) was well described by a gradual function M(D)=kD x . DMF values of the induced mutagenesis amounted to 2 for strains TA100 and TA102, and 1.5 for strain TA98

  14. Delayed manifestation and transmission bias of de novo chromosome mutations. Their relevance for radiation health effect

    International Nuclear Information System (INIS)

    Sasaki, Masao S.

    2006-01-01

    The origin and transmission of de novo chromosome mutations were reviewed on the basis of our chromosome studies in retinoblastoma patients and male infertility. In a series of 264 sporadic retinoblastoma families, gross chromosome rearrangements involving the RB1 locus were identified in 23 cases (8.7%), of which 16 were non-mosaic and 7 were mosaic mutations. The newly formed chromosome mutations, whether they were non-mosaic or mosaic, had a strong bias towards paternally derived chromosome, indicating that they shared a common mechanism where a pre-mutational event or instability is carried over to zygote by sperm and manifested as gross chromosome mutation at the early stages of development. The de novo chromosome mutations are preferentially transmitted through female carriers. This transmission bias is consistent with the finding of higher frequencies of translocation carriers in infertile men (7.69% versus 0.27% in general populations) in whom meiotic progression is severely suppressed, possibly through activation of meiotic checkpoints. Such a meiotic surveillance mechanism may minimize the spreading of newly-arisen chromosome mutations in populations. A quantitative model of meiotic surveillance mechanism is proposed and successfully applied to the published data on ''humped'' dose-response curves for radiation-induced spermatogonial reciprocal translocations in several mammalian species. (author)

  15. Bystander Effect Induced by UV Radiation; why should we be interested? 

    Directory of Open Access Journals (Sweden)

    Maria Widel

    2012-11-01

    Full Text Available The bystander effect, whose essence is an interaction of cells directly subjected to radiation with adjacent non-subjected cells, via molecular signals, is an important component of ionizing radiation action. However, knowledge of the bystander effect in the case of ultraviolet (UV radiation is quite limited. Reactive oxygen and nitrogen species generated by UV in exposed cells induce bystander effects in non-exposed cells, such as reduction in clonogenic cell survival and delayed cell death, oxidative DNA damage and gene mutations, induction of micronuclei, lipid peroxidation and apoptosis. Although the bystander effect after UV radiation has been recognized in cell culture systems, its occurrence in vivo has not been studied. However, solar UV radiation, which is the main source of UV in the environment, may induce in human dermal tissue an inflammatory response and immune suppression, events which can be considered as bystander effects of UV radiation. The oxidative damage to DNA, genomic instability and the inflammatory response may lead to carcinogenesis. UV radiation is considered one of the important etiologic factors for skin cancers, basal- and squamous-cell carcinomas and malignant melanoma. Based on the mechanisms of actions it seems that the UV-induced bystander effect can have some impact on skin damage (carcinogenesis?, and probably on cells of other tissues. The paper reviews the existing data about the UV-induced bystander effect and discusses a possible implication of this phenomenon for health risk. 

  16. Effect of uvs1, uvs2 and xrs mutations on the radiosensitivity and the induced mitotic recombination frequency in diploid yeast cells

    International Nuclear Information System (INIS)

    Suslova, N.G.; Fedorova, I.V.; Zheleznyakova, N.Yu.

    1975-01-01

    The influence of the loci of radiosensitivity uvs1, uvs2, and xrs in the homozygous state at the diploid level on the sensitivity to UV and ionizing radiation and induced mitotic recombination was studied in the yeast Sacch. cerevisiae. Hypersensitivity to UV irradiation was detected in the diploids uvs2 uvs2 xrs xrs in comparision with the corresponding control. The diploid uvs1 uvs1 uvs2 uvs2 does not differ in UV sensitivity from the diploid uvs1 uvs1 UVS2 UVS2. These facts demonstrate that the uvs1 and uvs2 mutations, on the one hand, and the xrs mutations, on the other, normally control different pathways of elimination of UV-induced damages. It was shown that the diploid uvs2 uvs2 xrs3 xrs3 is far more sensitive to the lethal action of x rays than the control diploid UVS2 UVS2 xrs3 xrs3. Consequently, the mutations uvs2 and xrs3 block different modes of repair of damages induced by ionizing radiation. In all the double-mutant diploids, the frequency of mitotic recombination induced by UV rays increases sharply in comparison with that of the radioresistant diploids UVS UVS XRS XRS and the UV-sensitive diploids uvs2 uvs2 XRS XRS. Possible causes of the observed phenomenon are discussed. It was established that in a diploid homozygous for the loci uvs2 xrs5, the frequency of mitotic recombination induced by x rays increases extremely sharply. This fact confirms the hypothesis that the gene product of the locus uvs2 participates in the repair of DNA after the action of ionizing radiation. (author)

  17. Fate of induced mutations in higher plants with special emphasis on sexually reproducing species

    International Nuclear Information System (INIS)

    Cornu, Andre

    1978-01-01

    A mutation induced in a plant somatic cell has to overcome quite many difficulties before being isolated and utilized as a marker in a mutated line. If induced in a meristem, three conditions must be fulfilled for the mutation to be transmitted to the subsequent generation: it must be compatible with normal cell multiplication, it must be located in a cell mass that will provide an inflorescence, and it must be in the sporogenetic layer (t2). Under these conditions, or if it is induced in a gamete or in a zygote, the mutation enters a first cycle of sexual reproduction. Meiosis and the subsequent haploid phase constitute severe screening steps for many chromosome aberrations. Studies on Petunia performed by means of marker genes show that male and female gametic viabilities are drastically impaired by deletions. However, a deficient chromosome can be transmitted when the losss of information is compensated for by homologous information as, for example, diploid gametes from tetraploids or disomic gametes resulting from non-disjunction. If partial or complete sterility, whether sporo- or gametophytic, is avoided, then the mutation can be transmitted to the next generation in heterozygous state. When becoming homozygous, the mutation may have effects such that its use can be most difficult. This is the case when this mutation causes rather early lethality or severe sterility. Thus, in higher plants, one faces several cases of powerful and efficient selection against mutations. On the basis of experiments carried out on Petunia, the per locus mutation rate of practical interest ranges between I and 5/10000M 1 plants. Practical conclusions are drawn about which organ should be treated, which mutagen at what dose should be used according to the scope of the research undertaken [fr

  18. Mutation breeding newsletter. No. 28

    International Nuclear Information System (INIS)

    1986-09-01

    This issue of the Newsletter presents reports and research abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  19. Mutation breeding newsletter. No. 24

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1984-07-01

    This issue of the Newsletter presents reports and research abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  20. Mutation breeding newsletter. No. 36

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1990-07-01

    This issue of the Newsletter presents abstracts and short communications of research results on radiation and chemical induced mutation breeding projects. Positive traits such as disease resistance and increased productivity are highlighted.

  1. Mutation breeding newsletter. No. 34

    International Nuclear Information System (INIS)

    1989-07-01

    This issue of the Newsletter presents abstracts and short communications of research results on radiation and chemical induced mutation breeding projects. Positive traits such as disease resistance and increased productivity are highlighted

  2. Mutation breeding newsletter. No. 34

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1989-07-01

    This issue of the Newsletter presents abstracts and short communications of research results on radiation and chemical induced mutation breeding projects. Positive traits such as disease resistance and increased productivity are highlighted.

  3. Mutation breeding newsletter. No. 25

    International Nuclear Information System (INIS)

    1985-01-01

    This issue of the Newsletter presents reports and research abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  4. Mutation breeding newsletter. No. 28

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1986-09-01

    This issue of the Newsletter presents reports and research abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  5. Mutation breeding newsletter. No. 26

    International Nuclear Information System (INIS)

    1985-10-01

    This issue of the Newsletter presents reports and research abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  6. Mutation breeding newsletter. No. 27

    International Nuclear Information System (INIS)

    1986-02-01

    This issue of the Newsletter presents reports and research abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  7. Mutation breeding newsletter. No. 24

    International Nuclear Information System (INIS)

    1984-07-01

    This issue of the Newsletter presents reports and research abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  8. Mutation breeding newsletter. No. 26

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1985-10-01

    This issue of the Newsletter presents reports and research abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  9. Mutation breeding newsletter. No. 25

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1985-01-01

    This issue of the Newsletter presents reports and research abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  10. Mutation breeding newsletter. No. 27

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1986-02-01

    This issue of the Newsletter presents reports and research abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  11. Mutation breeding newsletter. No. 36

    International Nuclear Information System (INIS)

    1990-07-01

    This issue of the Newsletter presents abstracts and short communications of research results on radiation and chemical induced mutation breeding projects. Positive traits such as disease resistance and increased productivity are highlighted

  12. Experimental mutations in soybean and their selection value

    International Nuclear Information System (INIS)

    Sichkar', V.I.

    1979-01-01

    Efficiency of widely used chemical mutagens and gamma irradiation in inducing chlorophyll changes in some soya varieties has been compared in order to further specify the relationship between this type of mutations and other morphological changes. The most active mutations found were NMU, NEU, EI and gamma radiation. The frequency of chrolophyll changes depended on the mutagen concentration and soya variety and varied from 1.58% to 19.04%. EO, NDMM and DMS produced 4-5 times lower yield of chlorophyll mutations. The following mutagen concentrations for the varieties studied were found optimum (in per cent): NMU - 0.0125, NEU - 0.025, EI - 0.03, EO - 0.05, NDMM - 0.0O625, DMS - 0.02. No relationship between the dose of gamma radiation and the mutation frequency was found. Varieties of VNIIMK 9186 and Lanka were the most mutable, 89-10 hybrid showed very low mutability. Mutagens that induced high frequency of mutations also gave the broadest spectrum of changes. Most frequent changes were xantha, lutescens and xanthaterminalis. Very few mutations from green color to white one were isolated

  13. Somatic gene mutation in the human in relation to radiation risk

    International Nuclear Information System (INIS)

    Mendelsohn, M.L.

    1992-01-01

    This report discusses the measurement of somatic gene-mutation frequencies in the human. We ask the following questions. How well can they be measured? Do they respond to radiation? Can they also function as a dosimeter? What do they tell us about the somatic mutation theory of carcinogenesis?

  14. Homozygous mutations in the Fhit gene results in resistance to ionizing radiation and inhibition of apoptosis

    International Nuclear Information System (INIS)

    Turner, B.C.; Potoczek, M.B.; Ottey, M.; Croce, C.M.; Huebner, K.

    2001-01-01

    Purpose: The Fhit gene was identified because it represents the most active constitutive chromosome fragile site and has functions often associated with a tumor suppressor gene. Mutations in the Fhit locus have been identified in many cancer-derived cell lines, primary human tumors including lung, head and neck, colon, breast, and esophagus, and are associated with tobacco-induced lung cancers. In this study, we examined the cellular response of mouse epithelial cells with complete loss of Fhit to therapeutic doses of ionizing radiation and the prognostic importance of Fhit protein in early stage breast cancer patients treated with breast conserving therapy. Materials and Methods: Mouse epithelial cell lines containing either homozygous mutant Fhit -/- or wild-type Fhit +/+ were derived from mice (C57BL/6J X 129/SvJ) with either wild-type or inactivated Fhit gene. Clonogenic cell survival assays were carried out on subconfluent cells in logarithmic growth using a 137 Cs irradiator and survival curves were plotted as the log of the surviving cells versus dose and corrected for cloning efficiency. Apoptosis following ionizing radiation was determined by flow cytometry using the Annexin-V FITC kit and DAPI staining. Paraffin-embedded breast tumor blocks were obtained from 42 women with local breast tumor recurrence and 42 matched breast cancer patients without local cancer relapse treated with breast conserving therapy and stained with a 1:4000 dilution of polyclonal antibody to the Fhit protein and scored based on both intensity and distribution of Fhit staining within the invasive breast cancer component. Results: Treatment of Fhit -/- mouse epithelial cells with single fraction doses of ionizing radiation including 2, 4, 6, and 10 Gy result in 4-6 fold increase in cellular survival compared with isogenic parental cells from Fhit +/+ mice. Fhit -/- epithelial cells displayed 3-5 fold lower levels of apoptosis in response to both low and high doses of ionizing

  15. Imaging Features that Discriminate between Foci Induced by High-and Low-LET Radiation in Human Fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Costes, Sylvain V.; Boissiere, Arnaud; Ravani, Shraddha; Romano,Raquel; Parvin, Bahram; Barcellos-Hoff, Mary Helen

    2006-10-08

    In this study, we investigated the formation ofradiation-induced foci in normal human fibroblasts exposed to X rays or130 keV/mum nitrogen ions using antibodies to phosphorylated proteinkinase ataxia telangiectasia mutated (ATMp) and histone H2AX(gamma-H2AX). High-content automatic image analysis was used to quantifythe immunofluorescence of radiation-induced foci. The size ofradiation-induced foci increased for both proteins over a 2-h periodafter nitrogen-ion irradiation, while the size of radiation-induced focidid not change after exposure to low-LET radiation. The number ofradiation-induced ATMp foci showed a more rapid rise and greaterfrequency after X-ray exposure and was resolved more rapidly such thatthe frequency of radiation-induced foci decreased by 90 percent comparedto 60 percent after exposure to high-LET radiation 2 h after 30 cGy. Incontrast, the kinetics of radiation-induced gamma-H2AX focus formationwas similar for high- and low-LET radiation in that it reached a plateauearly and remained constant for up to 2 h. High-resolution 3D images ofradiation-induced gamma-H2AX foci and dosimetry computation suggest thatmultiple double-strand breaks from nitrogen ions are encompassed withinlarge nuclear domains of 4.4 Mbp. Our work shows that the size andfrequency of radiation-induced foci vary as a function of radiationquality, dose, time and protein target. Thus, even though double-strandbreaks and radiation-induced foci are correlated, the dynamic nature ofboth contradicts their accepted equivalence for low doses of differentradiation qualities.

  16. Mutation breeding newsletter. No. 4

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1974-08-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  17. Mutation breeding newsletter. No. 6

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1975-08-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  18. Mutation breeding newsletter. No. 5

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1975-02-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  19. Mutation breeding newsletter. No. 3

    International Nuclear Information System (INIS)

    1974-01-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  20. Mutation breeding newsletter. No. 3

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1974-01-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  1. Mutation breeding newsletter. No. 29

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1987-02-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  2. Mutation breeding newsletter. No. 4

    International Nuclear Information System (INIS)

    1974-08-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  3. Mutation breeding newsletter. No. 7

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1976-01-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  4. Mutation breeding newsletter. No. 44

    International Nuclear Information System (INIS)

    1999-04-01

    This issue of the Newsletter presents research reports on the role of radiation induced mutation and chemical mutagens in improving productivity, disease resistance; cold and salinity tolerance of various crops and ornamental plants

  5. Mutation breeding newsletter. No. 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1972-05-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  6. Mutation breeding newsletter. No. 29

    International Nuclear Information System (INIS)

    1987-02-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  7. Mutation breeding newsletter. No. 5

    International Nuclear Information System (INIS)

    1975-02-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  8. Mutation breeding newsletter. No. 2

    International Nuclear Information System (INIS)

    1973-02-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  9. Mutation breeding newsletter. No. 1

    International Nuclear Information System (INIS)

    1972-05-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  10. Mutation breeding newsletter. No. 6

    International Nuclear Information System (INIS)

    1975-08-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  11. Mutation breeding newsletter. No. 7

    International Nuclear Information System (INIS)

    1976-01-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants

  12. Mutation breeding newsletter. No. 2

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1973-02-01

    This issue of the Newsletter presents reports and rea search abstracts on mutation breeding programs using radiation or chemical mutagenesis to improve productivity, introduce disease resistance or induce morphological changes in crop plants.

  13. SOLAR RADIATION AND INDUCTION OF DNA DAMAGE, MUTATIONS AND SKIN CANCERS.

    Energy Technology Data Exchange (ETDEWEB)

    SETLOW,R.B.

    2007-05-10

    An understanding of the effects of sunlight on human skin begins with the effects on DNA and extends to cells, animals and humans. The major DNA photoproducts arising from UVB (280-320 nm) exposures are cyclobutane pyrimidine dimers. If unrepaired, they may kill or mutate cells and result in basal and squamous cell carcinomas. Although UVA (320-400 nm) and visible wavelengths are poorly absorbed by DNA, the existing data indicate clearly that exposures to these wavelengths are responsible, in an animal model, for {approx}95 % of the incidence of cutaneous malignant melanoma (CMM). Six lines of evidence, to be discussed in detail, support the photosensitizing role of melanin in the induction of this cancer. They are: (1) Melanomas induced in backcross hybrids of small tropical fish of the genus Xiphophorus, exposed to wavelengths from 302-547 nm, indicate that {approx}95% of the cancers induced by exposure to sunlight would arise from UVA + visible wavelengths; (2) The action spectrum for inducing melanin-photosensitized oxidant production is very similar to the spectrum for inducing melanoma; (3) Albino whites and blacks, although very sensitive to sunburn and the sunlight induction of non-CMM, have very low incidences of CMM; (4) The incidence of CMM as a function of latitude is very similar to that of UVA, but not UVB; (5) Use of UVA-exposing sun-tanning parlors by the young increases the incidence rate of CMM and (6) Major mutations observed in CMM are not UVB-induced.

  14. The use of optical markers for mutation breeding

    International Nuclear Information System (INIS)

    Makino, Takahiro

    2003-01-01

    The use of radiation for mutation breeding has produced many kinds of practical varieties in crops and ornamental plants over the last several decades. Cold-tolerant rice and disease-resistant apple and pears are well-known varieties resulting from radiation breeding in Japan, and X-ray mutations were used routinely for the expansion of petal color in the chrysanthemum. Recently, the use of ion-beams for mutation induction was investigated as an effective source for producing varieties in cereal crops and flowers in Japan and China (Harten, 1998). Although we have not produced many varieties through radiation breeding, the success rate could increase with the addition of more resources. The success of mutation breeding greatly depends on the rate of mutation, the number of screened plants, and the mutation efficiency. The mutation rate is mainly a function of the total dose of the mutagen employed, although it can be modified by physical and biological factors. A large number of reports have been produced and effective methods of mutation treatments, such as gamma rays, established. Using higher doses inevitably brings about mortality, high pollen and seed sterility, and deleterious mutations. A practical useful dosage is usually found in the range much less than the maximum dose that can be applied. To increase the efficiency of mutation breeding, improvement of screening methods is more important than trials used for raising mutation probabilities. For this reason, we began studies to develop non-destructive and non-invasive optical high-throughput screening systems to increase the efficiency of mutation breeding. (author)

  15. Mutation breeding in crop improvement - achievements and prospects

    International Nuclear Information System (INIS)

    Kharkwal, M.C.

    2004-01-01

    Crop improvement programmes through induced mutations were initiated about seven decades ago. Majority of the mutant varieties have been released during the last two decades. In terms of the development and release of mutant varieties, China (605), India (309), Russia (204), the Netherlands (176), USA (125) and Japan (120) are the leading countries. Radiation, especially gamma radiation was the most frequently used mutagen for inducing mutations in crop plants. Out of 1072 mutant varieties of cereals, rice alone accounts for 434 varieties followed by barley (269). Mutation breeding has made significant contribution in increasing the production of rice, ground nut, castor, chickpea, mungbean and urd bean in the Indian subcontinent. The future mutation breeding programmes should be aimed at improving the root characters, nodulation in legumes, alteration of fatty acid composition in oil seeds, host pathogen interactions, photo- insensitivity and apomixix in crop plants

  16. Manual on mutation breeding. 2. ed.

    International Nuclear Information System (INIS)

    1977-01-01

    The manual is a compilation of work done on the use of induced mutations in plant breeding, and presents general methods and techniques in this field. The use of chemical mutagens and ionizing radiations (X-rays, gamma rays, α- and β-particles, protons, neutrons) are described as well as the effects of these mutagens. The different types of mutations achieved can be divided into genome mutations, chromosome mutations and extra nuclear mutations. Separate chapters deal with mutation techniques in breeding seed-propagated species and asexually propagated plants (examples of development of cultivars given). Plant characters which can be improved by mutation breeding include yield, ripening time, growth habit, disease resistance and tolerance to environmental factors (temperature, salinity etc.). The use of mutagens for some specific plant breeding problems is discussed and attention is also paid to somatic cell genetics in connection with induced mutations. The manual contains a comprehensive bibliography (60 p. references) and a subject index

  17. Rooting, growth, and color mutation of poinsettias affected by gamma radiation

    International Nuclear Information System (INIS)

    Lee, Eun Kyung; Kim, Won Hee; Kim, Seung Tae; Kang, Si Yong

    2010-01-01

    This experiment was carried out to investigate the effects of gamma-radiation on the rooting, growth, and color mutation in poinsettia. Using 10 poinsettia varieties ('Lollipop', 'Little Peace', 'Happy Day', 'Early Bird', 'Pixy Red', 'Happy Time', 'Heidi', 'Red Bell', 'Clara', and 'Scarlet') bred by National Institute of Horticultural and Herbal Science, 100 Gy of gamma ray was irradiated at the stage of callused cuttings. Four weeks after sticking cuttings in the rooting media, 8 cultivars showed 100% of root formation, but 'Early Bird' rooted 24.4% and even died off during the cutting propagation. After planting rooted cuttings, survival rate until flowering time varied among irradiated cultivars. While 'Pixy Red' and 'Heidi' survived about 98%, 'Clara', 'Happy Day', and 'Early Bird' survived lesser than 30%. All irradiated plants showed remarkably shorter plant height, lesser branch numbers than non-irradiated control plants. Thirty color mutants were obtained among 281 plants survived until flowering time. Nine were complete color mutated branches, whereas 21 mutants were partially color mutated bracts and transitional leaves. Color patterns mutated by 100 Gy of gamma ray were divided into pink, hot pink, light red and spotted (pink spots with red main color). Pink mutants were commonly obtained. Complete color mutants were discovered from 4 plants of 'Pixy Red', 2 plants of 'Red Bell' and 3 plants of Lollipop

  18. RBE [relative biological effectiveness] of tritium beta radiation to gamma radiation and x-rays analyzed by both molecular and genetic methods

    International Nuclear Information System (INIS)

    Lee, W.R.

    1988-01-01

    The relative biological effectiveness (RBE) of tritium beta radiation to 60 Co gamma radiation was determined using sex-linked recessive lethals (SLRL) induced in Drosophila melanogaster spermatozoa as the biological effect. The SLRL test, a measure of mutations induced in germ cells transmitted through successive generations, yields a linear dose-response curve in the range used in these experiments. From these ratios of the slopes of the 3 H beta and the 60 Co gamma radiation linear dose response curves, an RBE of 2.7 is observed. When sources of error are considered, this observation suggests that the tritium beta particle is 2.7 ± 0.3 times more effective per unit of energy absorbed in inducing gene mutations transmitted to successive generation than 60 Co gamma radiation. Ion tracks with a high density of ions (high LET) are more efficient than tracks with a low ion density (low LET) in inducing transmissible mutations, suggesting interaction among products of ionization. Molecular analysis of x-ray induced mutations shows that most mutations are deletions ranging from a few base pairs as determined from sequence data to multi locus deletions as determined from complementation tests and Southern blots. 14 refs., 1 fig

  19. Induced of plastid mutations in soybean plant (Glycine max L. Merrill) with gamma radiation and determination with RAPD

    International Nuclear Information System (INIS)

    Atak, Cimen; Alikamanoglu, Sema; Acik, Leyla; Canbolat, Yasemin

    2004-01-01

    The aim of our study was to induce with radiation of atrazine resistant and tolerated mutants in Coles, Amsoy-71 and 1937 soybean varieties. Atrazine that is photosynthetic inhibitor is the most important herbicide of S-triazin group, and shows toxic effect on soybean plant. For the improvement of the atrazine resistant plants with mutation breeding, the seeds belonging to the three varieties were irradiated with 200 Gy of gamma radiation dose. The irradiated seeds were sown in the field and at the end of harvesting season, every pod at node situated on the main stem was picked up separately and M 2 generations were obtained. At the plants, which were obtained from M 2 generation, chlorophyll mutants were determined and atrazine selection was made. The percentage of chlorophyll mutants for Amsoy-71, Coles and 1937 soybean varieties were found as 1.07, 1.48 and 1.32, respectively. At the end of atrazine selection, the percentages of atrazine resistant plants for Amsoy-71, Coles and 1937 soybean varieties were 0.80, 0.60 and 0.53, respectively. The percentages of atrazine tolerated plants were 1.07, 1.18 and 1.05, respectively as well. In our research; the differences among the mutants replying to atrazine in various concentrations were examined by using RAPD procedure as the molecular marker techniques in comparison with polymorphism. In the study done by using 14 primers; according to the amplification results, the differences between atrazine resistant plants were shown

  20. Determining Y-STR mutation rates in deep-routing genealogies: Identification of haplogroup differences.

    Science.gov (United States)

    Claerhout, Sofie; Vandenbosch, Michiel; Nivelle, Kelly; Gruyters, Leen; Peeters, Anke; Larmuseau, Maarten H D; Decorte, Ronny

    2018-05-01

    Knowledge of Y-chromosomal short tandem repeat (Y-STR) mutation rates is essential to determine the most recent common ancestor (MRCA) in familial searching or genealogy research. Up to now, locus-specific mutation rates have been extensively examined especially for commercially available forensic Y-STRs, while haplogroup specific mutation rates have not yet been investigated in detail. Through 450 patrilineally related namesakes distributed over 212 deep-rooting genealogies, the individual mutation rates of 42 Y-STR loci were determined, including 27 forensic Y-STR loci from the Yfiler ® Plus kit and 15 additional Y-STR loci (DYS388, DYS426, DYS442, DYS447, DYS454, DYS455, DYS459a/b, DYS549, DYS607, DYS643, DYS724a/b and YCAIIa/b). At least 726 mutations were observed over 148,596 meiosis and individual Y-STR mutation rates varied from 2.83 × 10 -4 to 1.86 × 10 -2 . The mutation rate was significantly correlated with the average allele size, the complexity of the repeat motif sequence and the age of the father. Significant differences in average Y-STR mutations rates were observed when haplogroup 'I & J' (4.03 × 10 -3 mutations/generation) was compared to 'R1b' (5.35 × 10 -3 mutations/generation) and to the overall mutation rate (5.03 × 10 -3 mutations/generation). A difference in allele size distribution was identified as the only cause for these haplogroup specific mutation rates. The haplogroup specific mutation rates were also present within the commercially available Y-STR kits (Yfiler ® , PowerPlex ® Y23 System and Yfiler ® Plus). This observation has consequences for applications where an average Y-STR mutation rate is used, e.g. tMRCA estimations in familial searching and genealogy research. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Radiation-induced genomic instability: Are epigenetic mechanisms the missing link?

    Energy Technology Data Exchange (ETDEWEB)

    Aypar, Umut; Morgan, William F.; Baulch, Janet E.

    2011-02-01

    Purpose: This review examines the evidence for the hypothesis that epigenetics are involved in the initiation and perpetuation of radiation-induced genomic instability (RIGI). Conclusion: In addition to the extensively studied targeted effects of radiation, it is now apparent that non-targeted delayed effects such as RIGI are also important post-irradiation outcomes. In RIGI, unirradiated progeny cells display phenotypic changes at delayed times after radiation of the parental cell. RIGI is thought to be important in the process of carcinogenesis, however, the mechanism by which this occurs remains to be elucidated. In the genomically unstable clones developed by Morgan and colleagues, radiation-induced mutations, double-strand breaks, or changes in mRNA levels alone could not account for the initiation or perpetuation of RIGI. Since changes in the DNA sequence could not fully explain the mechanism of RIGI, inherited epigenetic changes may be involved. Epigenetics are known to play an important role in many cellular processes and epigenetic aberrations can lead to carcinogenesis. Recent studies in the field of radiation biology suggest that the changes in methylation patterns may be involved in RIGI. Together these clues have led us to hypothesize that epigenetics may be the missing link in understanding the mechanism behind RIGI.

  2. The experience of induction of mutation on barley in Peru

    International Nuclear Information System (INIS)

    Romero Loli, M.; Pozo Cardenas, M.; Gomez Pando, L.

    1984-01-01

    Work on induced mutation of barley was started in 1978 under the Programme of Cereal Improvement. Barley was irradiated with gamma radiation at doses of 12, 15, 18, 21, and 24 Krad. Radiation doses of 18 and 21 Krad gave the highest frequency of albino and cloroticos mutants. Induced mutation is being carried out in different parts of the country to develop mutants having early germination property. These mutants will play an important role in the late cultivation in the mountain areas of Peru

  3. From molecular genetics to phylodynamics: evolutionary relevance of mutation rates across viruses.

    Directory of Open Access Journals (Sweden)

    Rafael Sanjuán

    Full Text Available Although evolution is a multifactorial process, theory posits that the speed of molecular evolution should be directly determined by the rate at which spontaneous mutations appear. To what extent these two biochemical and population-scale processes are related in nature, however, is largely unknown. Viruses are an ideal system for addressing this question because their evolution is fast enough to be observed in real time, and experimentally-determined mutation rates are abundant. This article provides statistically supported evidence that the mutation rate determines molecular evolution across all types of viruses. Properties of the viral genome such as its size and chemical composition are identified as major determinants of these rates. Furthermore, a quantitative analysis reveals that, as expected, evolution rates increase linearly with mutation rates for slowly mutating viruses. However, this relationship plateaus for fast mutating viruses. A model is proposed in which deleterious mutations impose an evolutionary speed limit and set an extinction threshold in nature. The model is consistent with data from replication kinetics, selection strength and chemical mutagenesis studies.

  4. Mechanisms of transient radiation-induced creep

    International Nuclear Information System (INIS)

    Pyatiletov, Yu.S.

    1981-01-01

    Radiation-induced creep at the transient stage is investigated for metals. The situation, when several possible creep mechanisms operate simultaneously is studied. Among them revealed are those which give the main contribution and determine thereby the creep behaviour. The time dependence of creep rate and its relation to the smelling rate is obtained. The results satisfactorily agree with the available experimental data [ru

  5. Molecular analysis of carbon ion-induced mutations in Arabidopsis thaliana

    International Nuclear Information System (INIS)

    Shikazono, Naoya; Tanaka, Atsushi; Watanabe, Hiroshi; Tano, Shigemitsu; Yokota, Yukihiko

    1998-01-01

    In order to elucidate the characteristics of the mutations induced by ion particles at the molecular level in plants, mutated loci in carbon ion-induced mutants of Arabidopsis were investigated by PCR and Southern blot analyses. In the present study, two lines of gl1 mutant and two lines of tt4 mutant were isolated after carbon ion-irradiation. Out of four mutants, one had a deletion, other two contained rearrangements, and one had a point-like mutation. From the present result, it was suggested that ion particles induced different kinds of alterations of the DNA and therefore they could produce various types of mutant alleles in plants. (author)

  6. ENU-induced phenovariance in mice: inferences from 587 mutations

    Directory of Open Access Journals (Sweden)

    Arnold Carrie N

    2012-10-01

    Full Text Available Abstract Background We present a compendium of N-ethyl-N-nitrosourea (ENU-induced mouse mutations, identified in our laboratory over a period of 10 years either on the basis of phenotype or whole genome and/or whole exome sequencing, and archived in the Mutagenetix database. Our purpose is threefold: 1 to formally describe many point mutations, including those that were not previously disclosed in peer-reviewed publications; 2 to assess the characteristics of these mutations; and 3 to estimate the likelihood that a missense mutation induced by ENU will create a detectable phenotype. Findings In the context of an ENU mutagenesis program for C57BL/6J mice, a total of 185 phenotypes were tracked to mutations in 129 genes. In addition, 402 incidental mutations were identified and predicted to affect 390 genes. As previously reported, ENU shows strand asymmetry in its induction of mutations, particularly favoring T to A rather than A to T in the sense strand of coding regions and splice junctions. Some amino acid substitutions are far more likely to be damaging than others, and some are far more likely to be observed. Indeed, from among a total of 494 non-synonymous coding mutations, ENU was observed to create only 114 of the 182 possible amino acid substitutions that single base changes can achieve. Based on differences in overt null allele frequencies observed in phenotypic vs. non-phenotypic mutation sets, we infer that ENU-induced missense mutations create detectable phenotype only about 1 in 4.7 times. While the remaining mutations may not be functionally neutral, they are, on average, beneath the limits of detection of the phenotypic assays we applied. Conclusions Collectively, these mutations add to our understanding of the chemical specificity of ENU, the types of amino acid substitutions it creates, and its efficiency in causing phenovariance. Our data support the validity of computational algorithms for the prediction of damage caused by

  7. Radiation-induced segregation in Cu-Au alloys

    International Nuclear Information System (INIS)

    Hashimoto, T.; Rehn, L.E.; Okamoto, P.R.

    1987-01-01

    Radiation-induced segregation in a Cu-lat.% Au alloy was investigated using in-situ Rutherford backscattering spectrometry. Irradiation with 1.8-MeV helium produced nonequilibrium gold atom depletion in the near surface region. The amount of segregation was measured as a function of dose, dose rate, and temperature. Segregation was observed in the temperature range between about 300 and 500 0 C. For a calculated dose rate of 3.9 x 10/sup -5/ dpa/s, the radiation-induced segregation rate peaked near 400 0 C. Theoretical analysis based on the Johnson-Lam model predicted that the amount of segregation would be directly proportional to dose at the early stage of irradiation, would deviate from linearity with a continuously decreasing slope of intermediate doses, and finally approach a constant value after high doses. The analysis also predicted that the segregation rate would vary as the - 1/4th power of the dose rate at constant dose in the low temperature region. These predictions were all verified experimentally. A procedure for extracting relative defect production efficiencies from similar measurements is discussed

  8. Radiation-induced erectile dysfunction: Recent advances and future directions

    Directory of Open Access Journals (Sweden)

    Javed Mahmood, PhD

    2016-07-01

    Full Text Available Prostate cancer is one of the most prevalent cancers and the second leading cause of cancer-related deaths in men in the United States. A large number of patients undergo radiation therapy (RT as a standard care of treatment; however, RT causes erectile dysfunction (radiation-induced erectile dysfunction; RiED because of late side effects after RT that significantly affects quality of life of prostate cancer patients. Within 5 years of RT, approximately 50% of patients could develop RiED. Based on the past and current research findings and number of publications from our group, the precise mechanism of RiED is under exploration in detail. Recent investigations have shown prostate RT induces significant morphologic arterial damage with aberrant alterations in internal pudendal arterial tone. Prostatic RT also reduces motor function in the cavernous nerve which may attribute to axonal degeneration may contributing to RiED. Furthermore, the advances in radiogenomics such as radiation induced somatic mutation identification, copy number variation and genome-wide association studies has significantly facilitated identification of biomarkers that could be used to monitoring radiation-induced late toxicity and damage to the nerves; thus, genomic- and proteomic-based biomarkers could greatly improve treatment and minimize arterial tissue and nerve damage. Further, advanced technologies such as proton beam therapy that precisely target tumor and significantly reduce off-target damage to vital organs and healthy tissues. In this review, we summarize recent advances in RiED research and novel treatment modalities for RiED. We also discuss the possible molecular mechanism involved in the development of RiED in prostate cancer patients. Further, we discuss various readily available methods as well as novel strategies such as stem cell therapies, shockwave therapy, nerve grafting with tissue engineering, and nutritional supplementations might be used to

  9. Ionizing radiation sensitivity and the rate of gross chromosomal rearrangement in yeast

    International Nuclear Information System (INIS)

    Brown, J.A.; Brown, M.

    2003-01-01

    Full text: Many of the genes conferring resistance to DNA damage in the yeast Saccharomyces cerevisiae have been identified. The systematic deletion of every open reading frame presents the opportunity to make great strides in determining the physiological role of many genes whose function has remained elusive. The ability to discriminate among all of the strains carrying unique non-essential gene deletions in a pool has allowed us to screen for novel genes required for survival to ionizing radiation. Many of these genes have not yet been characterized. A possible role for these genes could be in the initial sensing of the double strand break introduced by ionizing radiation, the cell cycle arrest permitting the cell time for the repair process, or directly in the repair. A consequence of a failure of any of these functions could result in an increase in mutation rate as well the more detrimental gross chromosomal rearrangement (GCR). We tested the hypothesis that any gene which when deleted caused an increase in ionizing radiation sensitivity would also demonstrate an increase in mutation rate and GCR. This turned out not to be the case with many having no significant increase and one in particular which caused a significant decrease in GCR. Data on several of the more intriguing genes will be presented

  10. Carbon Heavy-ion Radiation Induced Biological effects on Oryza sativa L.

    Science.gov (United States)

    Zhang, Meng; Sun, Yeqing; Li, Xishan; Gong, Ning; Meng, Qingmei; Liu, Jiawei; Wang, Ting

    2016-07-01

    Large number of researches on rice after spaceflights indicated that rice was a favorable model organism to study biological effects induced by space radiation. The stimulative effect could often be found on rice seedlings after irradiation by low-dose energetic heavy-ion radiation. Spaceflight also could induce stimulative effect on kinds of seeds. To further understand the mechanism of low-dose radiation biological effects and the dose range, the germinated rice seeds which were irradiated by different doses of carbon heavy-ion (0, 0.02, 0.1, 0.2, 1, 2, 5, 10, 15 and 20Gy, LET=27.3keV/µm) were used as materials to study. By investigating the variation of rice phenotype under different doses, we found that 2Gy radiation dose was a dividing point of the phenotypic variation. Transmission electron microscopy was used to observe the variation of mitochondria, chloroplast, endoplasmic reticulum, ribosome and nucleus in mesophyll cell of rice apical meristem at 24 hours after radiation with different doses. The cells were not apparently physiologically damaged when the dose of radiation was less than 2Gy. The number of chloroplast did not change significantly, but the number of mitochondria was significantly increased, and gathered around in the chloroplast and endoplasmic reticulum; the obvious lesion of chloroplast and mitochondria were found at the mesophyll cells when radiation dose was higher than 2Gy. The mitochondria were swelling and appearing blurred crest. The chloroplast and mitochondrial mutation rate increased significantly (pmitochondrial was an important organelle involved in the antioxidative systems, its dysfunction could result in the increase of reactive oxygen species and lipid peroxidation. We found that the growth stimulation induced by low-dose radiation mainly occurred at three-leaf stage along with the increasing activity of antioxidase system and damages of lipid peroxidation. We also found that the relative expression of genes sdhb and aox1a

  11. Is Increased Low-dose somatic Radiosensitivity Associated with Increased Transgenerational Germline Mutation

    International Nuclear Information System (INIS)

    Brenner, David J.

    2008-01-01

    Using single-molecule polymerase chain reaction, the frequency of spontaneous and radiation-induced mutation at an expanded simple tandem repeat (ESTR) locus was studied in DNA samples extracted from sperm and bone marrow of Atm knockout (Atm+/-) heterozygous male mice. The frequency of spontaneous mutation in sperm and bone marrow in Atm+/- males did not significantly differ from that in wild-type BALB/c mice. Acute gamma-ray exposure did not affect ESTR mutation frequency in bone marrow and resulted in similar increases in sperm samples taken from Atm+/- and BALB/c males. Taken together, these results suggest that the Atm haploinsufficiency analyzed in our study does not affect spontaneous and radiation-induced ESTR mutation frequency in mice

  12. Analysis of genes involved in the PI3K/Akt pathway in radiation- and MNU-induced rat mammary carcinomas.

    Science.gov (United States)

    Showler, Kaye; Nishimura, Mayumi; Daino, Kazuhiro; Imaoka, Tatsuhiko; Nishimura, Yukiko; Morioka, Takamitsu; Blyth, Benjamin J; Kokubo, Toshiaki; Takabatake, Masaru; Fukuda, Maki; Moriyama, Hitomi; Kakinuma, Shizuko; Fukushi, Masahiro; Shimada, Yoshiya

    2017-03-01

    The PI3K/AKT pathway is one of the most important signaling networks in human breast cancer, and since it was potentially implicated in our preliminary investigations of radiation-induced rat mammary carcinomas, our aim here was to verify its role. We included mammary carcinomas induced by the chemical carcinogen 1-methyl-1-nitrosourea to determine whether any changes were radiation-specific. Most carcinomas from both groups showed activation of the PI3K/AKT pathway, but phosphorylation of AKT1 was often heterogeneous and only present in a minority of carcinoma cells. The negative pathway regulator Inpp4b was significantly downregulated in both groups, compared with in normal mammary tissue, and radiation-induced carcinomas also showed a significant decrease in Pten expression, while the chemically induced carcinomas showed a decrease in Pik3r1 and Pdk1. Significant upregulation of the positive regulators Erbb2 and Pik3ca was observed only in chemically induced carcinomas. However, no genes showed clear correlations with AKT phosphorylation levels, except in individual carcinomas. Only rare carcinomas showed mutations in PI3K/AKT pathway genes, yet these carcinomas did not exhibit stronger AKT phosphorylation. Thus, while AKT phosphorylation is a common feature of rat mammary carcinomas induced by radiation or a canonical chemical carcinogen, the mutation of key genes in the pathways or permanent changes to gene expression of particular signaling proteins do not explain the pathway activation in the advanced cancers. Although AKT signaling likely facilitates cancer development and growth in rat mammary carcinomas, it is unlikely that permanent disruption of the PI3K/AKT pathway genes is a major causal event in radiation carcinogenesis. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

  13. Asymptotics of steady states of a selection–mutation equation for small mutation rate

    KAUST Repository

    Calsina, Àngel

    2013-12-01

    We consider a selection-mutation equation for the density of individuals with respect to a continuous phenotypic evolutionary trait. We assume that the competition term for an individual with a given trait depends on the traits of all the other individuals, therefore giving an infinite-dimensional nonlinearity. Mutations are modelled by means of an integral operator. We prove existence of steady states and show that, when the mutation rate goes to zero, the asymptotic profile of the population is a Cauchy distribution. © Royal Society of Edinburgh 2013.

  14. Asymptotics of steady states of a selection–mutation equation for small mutation rate

    KAUST Repository

    Calsina, À ngel; Cuadrado, Sí lvia; Desvillettes, Laurent; Raoul, Gaë l

    2013-01-01

    We consider a selection-mutation equation for the density of individuals with respect to a continuous phenotypic evolutionary trait. We assume that the competition term for an individual with a given trait depends on the traits of all the other individuals, therefore giving an infinite-dimensional nonlinearity. Mutations are modelled by means of an integral operator. We prove existence of steady states and show that, when the mutation rate goes to zero, the asymptotic profile of the population is a Cauchy distribution. © Royal Society of Edinburgh 2013.

  15. Particle-induced chromosome aberrations and mutations: an overview

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, S [Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany)

    1997-09-01

    This overview will focus on progress in chromosome and mutation studies achieved by the application of new techniques. Furthermore, recent relevant data on longterm genetic effects of densely ionizing radiation will be summarized. (orig./MG)

  16. Hyper-radiation sensitivity of murine scid mutation and mapping of the human homologue HYRC1 gene

    International Nuclear Information System (INIS)

    Komatsu, Kenshi; Ohta, Tohru; Niikawa, Norio; Okumura, Yutaka; Kubota, Nobuo.

    1994-01-01

    The murine severe combined immunodeficient mutation (scid) is characterized by a lack of both B and T cells, due to a defect in lymphoid variable-(diversity)-joining(V(D)J) rearrangement. Scid cells are highly sensitive to both radiation-induced killing and chromosomal aberrations. Present experiments also demonstrated the high sensitivity of scid cells to killing, because of a deficient repair of double strand breaks(DSB). Scid cells can repair only 60% of radiation-induced DSB for 3 hours, while normal cells repair 85% of the DSB. Significantly reduced Do and n values were obtained from survival curves of scid cells and were similar to ataxia-telangiectasia(AT) cells (a unique human disease conferring whole body radiosensitivity). However, the kinetics of DNA synthesis after irradiation were different between the two cell types. In contrast with the radioresistant DNA synthesis of AT cells, DNA synthesis of scid cells was markedly inhibited after irradiation. The existence of different mutations was also supported by evidence of complementation in somatic cell hybrids between scid cells and AT cells. Using these hybrid cells, fragments of human chromosome 8 were introduced into scid cells HPRT mutant via X-irradiation and somatic cell fusion. The resulting hybrid clones contained human DNA fragment(s) which complemented the hyper-radiosensitivity of the scid cells. Alu-PCR products from these hybrids were used for chromosome painting using the technique of chromosome in situ suppression hybridization, allowing assignment of the human HYRC1 (hyper-radiosensitivity of murine scid mutation, complementing 1) gene, a candidate for a V(D)J recombinant gene, to human chromosome 8q11. (author)

  17. Chromosomal instability induced by ionizing radiation

    International Nuclear Information System (INIS)

    Morgan, W.F.; Marder, B.A.; Day, J.P.

    1995-01-01

    There is accumulating evidence indicating genomic instability can manifest multiple generations after cellular exposure to DNA damaging agents. For instance, some cells surviving exposure to ionizing radiations show delayed reproductive cell death, delayed mutation and / or delayed chromosomal instability. Such instability, especially chromosome destabilization has been implicated in mutation, gene amplification, cellular transformation, and cell killing. To investigate chromosomal instability following DNA damage, we have used fluorescence in situ hybridization to detect chromosomal rearrangements in a human/hamster somatic hybrid cell line following exposure to ionizing radiation. Delayed chromosomal instability was detected when multiple populations of uniquely arranged metaphases were observed in clonal isolates raised from single cells. The relationship between delayed chromosomal destabilization and other endpoints of genomic instability, namely; delayed mutation and gene amplification will be discussed, as will the potential cytogenetic and molecular mechanisms contributing to delayed chromosomal instability

  18. Promotion of initiated cells by radiation-induced cell inactivation.

    Science.gov (United States)

    Heidenreich, W F; Paretzke, H G

    2008-11-01

    Cells on the way to carcinogenesis can have a growth advantage relative to normal cells. It has been hypothesized that a radiation-induced growth advantage of these initiated cells might be induced by an increased cell replacement probability of initiated cells after inactivation of neighboring cells by radiation. Here Monte Carlo simulations extend this hypothesis for larger clones: The effective clonal expansion rate decreases with clone size. This effect is stronger for the two-dimensional than for the three-dimensional situation. The clones are irregular, far from a circular shape. An exposure-rate dependence of the effective clonal expansion rate could come in part from a minimal recovery time of the initiated cells for symmetric cell division.

  19. [Dose rate-dependent cellular and molecular effects of ionizing radiation].

    Science.gov (United States)

    Przybyszewski, Waldemar M; Wideł, Maria; Szurko, Agnieszka; Maniakowski, Zbigniew

    2008-09-11

    The aim of radiation therapy is to kill tumor cells while minimizing damage to normal cells. The ultimate effect of radiation can be apoptotic or necrotic cell death as well as cytogenetic damage resulting in genetic instability and/or cell death. The destructive effects of radiation arise from direct and indirect ionization events leading to peroxidation of macromolecules, especially those present in lipid-rich membrane structures as well as chromatin lipids. Lipid peroxidative end-products may damage DNA and proteins. A characteristic feature of radiation-induced peroxidation is an inverse dose-rate effect (IDRE), defined as an increase in the degree of oxidation(at constant absorbed dose) accompanying a lower dose rate. On the other hand, a low dose rate can lead to the accumulation of cells in G2, the radiosensitive phase of the cell cycle since cell cycle control points are not sensitive to low dose rates. Radiation dose rate may potentially be the main factor improving radiotherapy efficacy as well as affecting the intensity of normal tissue and whole-body side effects. A better understanding of dose rate-dependent biological effects may lead to improved therapeutic intervention and limit normal tissue reaction. The study reviews basic biological effects that depend on the dose rate of ionizing radiation.

  20. Induced mutations in pomoid trees breeding

    International Nuclear Information System (INIS)

    Hamed, Faysal

    1986-01-01

    Induction of mutations in fruit trees by ionizing radiation complements a cross-breeding program. The objectives are: 1) the improvements of methods of induction, identification and selection of useful mutations, and 2) the initiation of useful mutations either for immediate use as improved cultivars or as a parent material for conventional cross-breeding. The induction of mutants in pomoid fruits, with special emphasis on apple, was realized by gamma-ray treatment of dormant scions subsequently propagated on a rootstoch in the nursery. The aim was to obtain compacts, presuming the feasibility of selecting compact shoots formed by the irradiated scions in the first vegetative generation and also assuming that chance of finding (e.g. fruit mutants) would be thus increased rather than lessened. Selection was carried out on one-season old shoots, formed on the same material for two or three seasons, by using a cut-back at the end of the first and second season. The procedure was highly effective. Moderate exposures, resulting in 60% survival gave high mutation frequencies. Buds 6-10 on the primary shoot gave higher frequencies of recognizable mutations than either buds 1-5 or 11-15. Preliminary results seem to indicate that, at least in some apple cultivars, there is opportunity to obtain compact growth types with good biological characteristics. 8 refs. (author)

  1. Using RADFET for the real-time measurement of gamma radiation dose rate

    Science.gov (United States)

    Andjelković, Marko S.; Ristić, Goran S.; Jakšić, Aleksandar B.

    2015-02-01

    RADFETs (RADiation sensitive Field Effect Transistors) are integrating ionizing radiation dosimeters operating on the principle of conversion of radiation-induced threshold voltage shift into absorbed dose. However, one of the major drawbacks of RADFETs is the inability to provide the information on the dose rate in real-time using the conventional absorbed dose measurement technique. The real-time monitoring of dose rate and absorbed dose can be achieved with the current mode dosimeters such as PN and PIN diodes/photodiodes, but these dosimeters have some limitations as absorbed dose meters and hence they are often not a suitable replacement for RADFETs. In that sense, this paper investigates the possibility of using the RADFET as a real-time dose rate meter so that it could be applied for simultaneous online measurement of the dose rate and absorbed dose. A RADFET sample, manufactured by Tyndall National Institute, Cork, Ireland, was tested as a dose rate meter under gamma irradiation from a Co-60 source. The RADFET was configured as a PN junction, such that the drain, gate and source terminals were grounded, while the radiation-induced current was measured at the bulk terminal, whereby the bulk was successively biased with 0 , 10 , 20  and 30 V. In zero-bias mode the radiation-induced current was unstable, but in the biased mode the current response was stable for the investigated dose rates from 0.65  to 32.1 Gy h-1 and up to the total absorbed dose of 25 Gy. The current increased with the dose rate in accordance with the power law, whereas the sensitivity of the current read-out was linear with respect to the applied bias voltage. Comparison with previously analyzed PIN photodiodes has shown that the investigated RADFET is competitive with PIN photodiodes as a gamma radiation dose rate meter and therefore has the potential to be employed for the real-time monitoring of the dose rate and absorbed dose.

  2. Using RADFET for the real-time measurement of gamma radiation dose rate

    International Nuclear Information System (INIS)

    Andjelković, Marko S; Ristić, Goran S; Jakšić, Aleksandar B

    2015-01-01

    RADFETs (RADiation sensitive Field Effect Transistors) are integrating ionizing radiation dosimeters operating on the principle of conversion of radiation-induced threshold voltage shift into absorbed dose. However, one of the major drawbacks of RADFETs is the inability to provide the information on the dose rate in real-time using the conventional absorbed dose measurement technique. The real-time monitoring of dose rate and absorbed dose can be achieved with the current mode dosimeters such as PN and PIN diodes/photodiodes, but these dosimeters have some limitations as absorbed dose meters and hence they are often not a suitable replacement for RADFETs. In that sense, this paper investigates the possibility of using the RADFET as a real-time dose rate meter so that it could be applied for simultaneous online measurement of the dose rate and absorbed dose. A RADFET sample, manufactured by Tyndall National Institute, Cork, Ireland, was tested as a dose rate meter under gamma irradiation from a Co-60 source. The RADFET was configured as a PN junction, such that the drain, gate and source terminals were grounded, while the radiation-induced current was measured at the bulk terminal, whereby the bulk was successively biased with 0 , 10 , 20  and 30 V. In zero-bias mode the radiation-induced current was unstable, but in the biased mode the current response was stable for the investigated dose rates from 0.65  to 32.1 Gy h −1 and up to the total absorbed dose of 25 Gy. The current increased with the dose rate in accordance with the power law, whereas the sensitivity of the current read-out was linear with respect to the applied bias voltage. Comparison with previously analyzed PIN photodiodes has shown that the investigated RADFET is competitive with PIN photodiodes as a gamma radiation dose rate meter and therefore has the potential to be employed for the real-time monitoring of the dose rate and absorbed dose. (paper)

  3. Improvement of mutation rate and reduction of somatic effects by double treatment of chemical mutagens in barley

    International Nuclear Information System (INIS)

    Koo, B.C.; Maluszynski, M.

    1996-01-01

    Mutation techniques inducing more useful mutations and reducing somatic effects need to be improved for crop breeding. Seeds of barley varieties; Dema, Grosso were treated with two types of mutagens; 1) chemical treatment: single treatment or double treatment of two mutagens (N-nitroso-N-methylurea ; MNH, Sodium Azide; NaN 3 ) 2) gamma ray irradiation treatment. After treatment, half of seeds were used for germination test and half of seeds were sown to the field. With the higher dose of mutagen both chemical and gamma ray were plants treated, the higher rate of growth reduction rate was in M 1 seedling. In chemical treatment, germination rate of seeds, growth rate of coleoptile and root in double treatment of chemical mutagens were better than single treatments, especially in same dose. Growth inhibition rate of plant in double treatment of 1.0 mM MNH (0.5 mM MNH + 0.5 mM MNH), for example, were less than one of plants of single treatment of 1.0 mM MNH in pot and petri dish test. Growth reduction rate of culm and fertility rate in M 1 plants double treated in same dose of single treatment were also less than single one. With the higher dose of mutagen both chemical and gamma ray were plants treated, the higher frequency of chlorophyll mutants was in M 2 seedling. The rate of chlorophyll mutants in double treatment of chemical mutagens were higher than single treatment. Double treatment methods can be a improved method for induction of new good mutants, which were induced more useful mutations and reduced harmful somatic effects

  4. Induced mutation for disease resistance in legumes

    International Nuclear Information System (INIS)

    Bravo, A.

    1984-01-01

    Mutation breeding has been used for developing genotypes that may contain resistance to: a) A necrotic strain of common mosaic virus, in common bean (Phaseolus vulgaris L.); b) Soil fungi causing root rots in chickpea (Cicer arietinum L.); c) The fungus Uromyces fabae that causes rust in lentil plants (Lens culinaria). Seeds of these three species were treated with gamma rays in doses of 1,000, 3,000, 6,000, and 9,000 rads. Treated materials and controls were grown during 1979. Chickpea M2 plants were grown in a naturally infested soil with soil-borne fungi. Lentil plants were sprayed with a suspension of spores of the rust fungus. Common bean M2 plants were sprayed with a solution containing virus particles. Ninety-three symptomless chickpea plants were identified in the M2 population. For lentil there were 47 symptomless plants and for common bean, 244 M2 plants with minor virus damage. Eight M3 progenies of chickpea, originated from symptomless M2 plants, had a high rate of survival and showed none or very little damage by root rots. In addition, some morphological changes were detected in other M3 chickpea progenies. Two progenies had larger leaflets, as compared to the control plants and those of other progenies. One progeny showed a more erect growth habit. These new traits have been attributed to genetic changes induced by the radiation treatments. By contrast to these promising results with chickpea no progress has been detected in the plant populations of common bean and lentil. (author)

  5. Characteristics of commercially recommending sesame mutant cultivars through induced mutations by different sources of radiation and chemical in the Republic of Korea

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Churl Whan [National Crop Experiment Station, Sodundong Suwon (Korea)

    2001-03-01

    The sesame acreage in Korea has grown 2.5 times in the last two decades as the result of recommending sesame mutant cultivars and polyethylene mulch technique newly developed since 1978. The mutation was induced by X-ray irradiation at 200 Gy yielding a variety named 'Ahnsankkae' known for early ripeness, white color of seed coat, tolerance for diseases. 'Suwon 128' is a dwarf mutant bred through sodium azide and known for strong lodging resistance, dense and lower first capsule set and dense planting adaptability toward mechanized culture against typhoon. Seven mutant recommending cultivars of sesame are compared with respect to their qualitative and quantitative characteristics based on passport data regarding different mutagen sources of radiations and chemicals published by Committee New Recommending Cultivars on the Crops. Breeding sources are summarized: 5 out of 7 sources are through radiation (X-rays, {gamma}-rays, and neutrons) and the rest 2 through chemicals. Their growth characteristics such as flowering date, maturing date, plant height, length-capsule bearing stem, disease and lodging resistance, oil content, and yield ability are also presented. (S. Ohno)

  6. An alternative derivation of the stationary distribution of the multivariate neutral Wright-Fisher model for low mutation rates with a view to mutation rate estimation from site frequency data.

    Science.gov (United States)

    Schrempf, Dominik; Hobolth, Asger

    2017-04-01

    Recently, Burden and Tang (2016) provided an analytical expression for the stationary distribution of the multivariate neutral Wright-Fisher model with low mutation rates. In this paper we present a simple, alternative derivation that illustrates the approximation. Our proof is based on the discrete multivariate boundary mutation model which has three key ingredients. First, the decoupled Moran model is used to describe genetic drift. Second, low mutation rates are assumed by limiting mutations to monomorphic states. Third, the mutation rate matrix is separated into a time-reversible part and a flux part, as suggested by Burden and Tang (2016). An application of our result to data from several great apes reveals that the assumption of stationarity may be inadequate or that other evolutionary forces like selection or biased gene conversion are acting. Furthermore we find that the model with a reversible mutation rate matrix provides a reasonably good fit to the data compared to the one with a non-reversible mutation rate matrix. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

  7. The application of a linear algebra to the analysis of mutation rates.

    Science.gov (United States)

    Jones, M E; Thomas, S M; Clarke, K

    1999-07-07

    Cells and bacteria growing in culture are subject to mutation, and as this mutation is the ultimate substrate for selection and evolution, the factors controlling the mutation rate are of some interest. The mutational event is not observed directly, but is inferred from the phenotype of the original mutant or of its descendants; the rate of mutation is inferred from the number of such mutant phenotypes. Such inference presumes a knowledge of the probability distribution for the size of a clone arising from a single mutation. We develop a mathematical formulation that assists in the design and analysis of experiments which investigate mutation rates and mutant clone size distribution, and we use it to analyse data for which the classical Luria-Delbrück clone-size distribution must be rejected. Copyright 1999 Academic Press.

  8. ATM Mutations and the Development of Severe Radiation-Induced Morbidity Following Radiotherapy for Breast Cancer

    National Research Council Canada - National Science Library

    Rosenstein, Barry S

    2005-01-01

    The hypothesis being tested in this project is that a greater proportion of patients who develop radiation-induced subcutaneous late tissue morbidity possess a variant allele in the ATM gene compared...

  9. ATM Mutations and the Development of Severe Radiation-Induced Morbidity Following Radiotherapy for Breast Cancer

    National Research Council Canada - National Science Library

    Rosenstein, Barry S

    2006-01-01

    The hypothesis being tested in this project is that a greater proportion of patients who develop radiation-induced subcutaneous late tissue morbidity possess a variant allele in the ATM gene compared...

  10. Mitochondrial Mutation Rate, Spectrum and Heteroplasmy in Caenorhabditis elegans Spontaneous Mutation Accumulation Lines of Differing Population Size.

    Science.gov (United States)

    Konrad, Anke; Thompson, Owen; Waterston, Robert H; Moerman, Donald G; Keightley, Peter D; Bergthorsson, Ulfar; Katju, Vaishali

    2017-06-01

    Mitochondrial genomes of metazoans, given their elevated rates of evolution, have served as pivotal markers for phylogeographic studies and recent phylogenetic events. In order to determine the dynamics of spontaneous mitochondrial mutations in small populations in the absence and presence of selection, we evolved mutation accumulation (MA) lines of Caenorhabditis elegans in parallel over 409 consecutive generations at three varying population sizes of N = 1, 10, and 100 hermaphrodites. The N =1 populations should have a minimal influence of natural selection to provide the spontaneous mutation rate and the expected rate of neutral evolution, whereas larger population sizes should experience increasing intensity of selection. New mutations were identified by Illumina paired-end sequencing of 86 mtDNA genomes across 35 experimental lines and compared with published genomes of natural isolates. The spontaneous mitochondrial mutation rate was estimated at 1.05 × 10-7/site/generation. A strong G/C→A/T mutational bias was observed in both the MA lines and the natural isolates. This suggests that the low G + C content at synonymous sites is the product of mutation bias rather than selection as previously proposed. The mitochondrial effective population size per worm generation was estimated to be 62. Although it was previously concluded that heteroplasmy was rare in C. elegans, the vast majority of mutations in this study were heteroplasmic despite an experimental regime exceeding 400 generations. The frequencies of frameshift and nonsynonymous mutations were negatively correlated with population size, which suggests their deleterious effects on fitness and a potent role for selection in their eradication. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. Kinetics of radiation-induced segregation in ternary alloys

    International Nuclear Information System (INIS)

    Lam, N.O.; Kumar, A.; Wiedersich, H.

    1982-01-01

    Model calculations of radiation-induced segregation in ternary alloys have been performed, using a simple theory. The theoretical model describes the coupling between the fluxes of radiation-induced defects and alloying elements in an alloy A-B-C by partitioning the defect fluxes into those occurring via A-, B-, and C-atoms, and the atom fluxes into those taking place via vacancies and interstitials. The defect and atom fluxes can be expressed in terms of concentrations and concentration gradients of all the species present. With reasonable simplifications, the radiation-induced segregation problem can be cast into a system of four coupled partial-differential equations, which can be solved numerically for appropriate initial and boundary conditions. Model calculations have been performed for ternary solid solutions intended to be representative of Fe-Cr-Ni and Ni-Al-Si alloys under various irradiation conditions. The dependence of segregation on both the alloy properties and the irradiation variables, e.g., temperature and displacement rate, was calculated. The sample calculations are in good qualitative agreement with the general trends of radiation-induced segregation observed experimentally

  12. Mutation induction in cultured human cells after low-dose and low-dose-rate γ-ray irradiation. Detection by LOH analysis

    International Nuclear Information System (INIS)

    Umebayashi, Yukihiro; Iwaki, Masaya; Yatagai, Fumio; Honma, Masamitsu; Suzuki, Masao; Suzuki, Hiromi; Shimazu, Toru; Ishioka, Noriaki

    2007-01-01

    To study the genetic effects of low-doses and low-dose-rate ionizing radiation (IR), human lymphoblastoid TK6 cells were exposed to 30 mGy of γ-rays at a dose-rate of 1.2 mGy/hr. The frequency of early mutations (EMs) in the thymidine kinase (TK) gene locus was determined to be 1.7 x 10 -6 , or 1.9-fold higher than the level seen in unirradiated controls. These mutations were analyzed with a loss of heterozygosity (LOH) detection system, a methodology which has been shown to be sensitive to the effects of radiation. Among the 15 EMs observed after IR exposure, 8 were small interstitial-deletion events restricted to the TK gene locus. However, this specific type of event was not found in unirradiated controls. Although these results were observed under the limited conditions, they strongly suggest that the LOH detection system can be used for estimating the genetic effects of a low-dose IR exposure delivered at a low-dose-rate. (author)

  13. RBE-LET relationships of high-LET radiations in drosophila mutations

    International Nuclear Information System (INIS)

    Yoshikawa, Isao; Takatsuji, Toshihiro; Nagano, Masaaki; Takada, Jun; Endo, Satoru; Hoshi, Masaharu

    1999-01-01

    The relative biological effectiveness (RBE) of 252 Cf neutrons and synchrotron-generated high-energy charged particles for mutation induction was evaluated as a function of linear energy transfer (LET), using the loss of heterozygosity for wing-hair mutations and the reversion of the mutant white-ivory eye-color in Drosophila melanogaster. Loss of heterozygosity for wing-hair mutations results predominantly from mitotic crossing over induced in wing anlage cells of larvae, while the reverse mutation of eye-color is due to an intragenic structural change (2.96 kb-DNA excision) in the white locus on the X-chromosome. The measurements were performed in a combined mutation assay system so that induced mutant wing-hair clones as well as revertant eye-color clone can be detected simultaneously in the same individual. Larvae were irradiated at the age of 3 days post oviposition with 252 Cf neutrons, carbon beam or neon beam. For the neutron irradiation, the RBE values for wing-hair mutations were larger than that for eye-color mutation by about 7 fold. The RBE of carbon ions for producing the wing-hair mutations increased with increase in LET. The estimated RBE values were found to be in the range 2 to 6.5 for the wing-hair. For neon beam irradiation, the RBE values for wing-hair mutations peak near 150 keV/μm and decrease with further increase in LET. On the other hand, the RBE values for the induction of the eye-color mutation are nearly unity in 252 Cf neutrons and both ions throughout the LET range irradiated. We discuss the relationships between the initial DNA damage and LET in considering the mechanism of somatic mutation induction. (author)

  14. Occurrence of mutations in the epidermal growth factor receptor gene in X-ray-induced rat lung tumors

    International Nuclear Information System (INIS)

    Kitahashi, Tsukasa; Takahashi, Mami; Yamada, Yutaka

    2008-01-01

    Epidermal growth factor receptor (EGFR) gene alterations have been found in human lung cancers. However, there is no information on the factors inducing EGFR mutations. In rodents, K-ras mutations are frequently found in many lung carcinogenesis models, but hitherto, Egfr mutations have not been reported. Their presence was therefore investigated in representative lung carcinogenesis models with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N-nitrosobis(2-hydroxypropyl)amine (BHP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MelQx) and ethyl carbamate (urethane), as well as X-ray irradiation. With the chemical carcinogenesis models, no mutations were detected in Egfr, which is in clear contrast to the high rates observed in either codon 12 or 61 of K-ras (21/23 of the lung tumors induced with NNK, 4/5 with MelQx, 1/4 with urethane and 7/18 with BHP). However, in the X-ray-induced lung tumors, Egfr mutations with amino acid substitution were observed in exons 18 and 21 (4/12, 33%), but no activating mutation of K-ras was detected. In addition, one and four silent mutations were identified in K-ras (exon 1) and Egfr (exons 18, 20 and 21), respectively. Most mutations in both Egfr and K-ras were G/C→A/T transitions (7/8, 88% and 31/34, 91%, respectively). Although, the mutational patterns in equivalent human lesions were not completely coincident, this first report of Egfr mutations in an experimental lung tumor model suggests that X-rays or other factors producing oxygen radicals could cause EGFR mutations in some proportion of lung cancers in humans. (author)

  15. International symposium on induced mutations in plants (ISIM). Book of abstracts

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2008-07-01

    The year 2008 will mark the 80th anniversary of mutation induction in crop plants. The application of mutation techniques, i.e. gamma rays and other physical and chemical mutagens, has generated a vast amount of genetic variability and has played a significant role in plant breeding and genetic studies. The widespread use of induced mutants in plant breeding programmes throughout the world has led to the official release of more than 2600 mutant crop varieties. A large number of these varieties (including cereals, pulses, oil, root and tuber crops, and ornamentals) have been released in developing countries, resulting in enormous positive economic impacts. The International Symposium on Induced Mutations in Plants (ISIM) will be the eighth in the Joint FAO/IAEA Programme's Symposium series dedicated exclusively to harnessing and disseminating information on current trends in induced mutagenesis in plants, the first of which was held in 1969 and the last in 1995. These previous symposia dealt with themes relating to the development of efficient protocols for induced mutagenesis and their role in the enhancement of quality traits, as well as resistance to biotic and abiotic stresses in crops and the integration of in vitro and molecular genetic techniques in mutation induction. Since 1995, there has been an increased interest within the scientific community, not only in the use of induced mutations for developing improved crop varieties and for the discovery of genes controlling important traits and in the understanding the functions and mechanisms of actions of these genes, but also in deciphering the biological nature of DNA damage, repair and mutagenesis. A symposium that brings together the key players in basic research, as well as in the development and application of technologies relating to the efficient use of induced mutations for crop improvement and empirical genetic studies, is therefore justified and necessary. Topics addressed at the symposium

  16. Induced plasmon mutations affecting the growth habit of peanuts, A. hypogaea L

    International Nuclear Information System (INIS)

    Levy, A.; Ashri, A.

    1978-01-01

    The effectiveness of the acridines ethidium bromide (EB) and acriflavine in inducing plasmon mutations was compared with the alkylating agents ethyl methanesulphonate (EMS) and diethyl sulphate and to γ-rays. The growth habit (trailing versus bunch) of peanuts (A. hypogaea), controlled by genic-cytoplasmic interactions, was utilized. Breeding tests distinguishing nuclear from plasmon mutations were developed and are described in detail. Plasmon mutations were induced, but there were differences in mutation yields between the cultivars and the mutagens. (Auth.)

  17. [Malignant transformation of human fibroblasts by neutrons and by gamma radiation: Relationship to mutations induced

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-12-31

    A brief overview if provided of selected reports presented at the International Symposium on Molecular Mechanisms of Radiation- and Chemical Carcinogen-Induced Cell Transformation held at Mackinac Island, Michigan on September 19-23, 1993.

  18. Mutation rate estimation for 15 autosomal STR loci in a large population from Mainland China.

    Science.gov (United States)

    Zhao, Zhuo; Zhang, Jie; Wang, Hua; Liu, Zhi-Peng; Liu, Ming; Zhang, Yuan; Sun, Li; Zhang, Hui

    2015-09-01

    STR, short tandem repeats, are well known as a type of powerful genetic marker and widely used in studying human population genetics. Compared with the conventional genetic markers, the mutation rate of STR is higher. Additionally, the mutations of STR loci do not lead to genetic inconsistencies between the genotypes of parents and children; therefore, the analysis of STR mutation is more suited to assess the population mutation. In this study, we focused on 15 autosomal STR loci. DNA samples from a total of 42,416 unrelated healthy individuals (19,037 trios) from the population of Mainland China collected between Jan 2012 and May 2014 were successfully investigated. In our study, the allele frequencies, paternal mutation rates, maternal mutation rates and average mutation rates were detected. Furthermore, we also investigated the relationship between paternal ages, maternal ages, area, the time of pregnancy and average mutation rate. We found that the paternal mutation rate was higher than the maternal mutation rate and the paternal, maternal, and average mutation rates had a positive correlation with paternal age, maternal age and the time of pregnancy respectively. Additionally, the average mutation rate of coastal areas was higher than that of inland areas.

  19. Induced mutations in connection with biotechnology for crop improvement in Latin America. Proceedings of a final research co-ordination meeting

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-05-01

    This publication results from the second Co-ordinated Research Project (CRP) on Plant Breeding and Genetics organized on a regional basis in Latin America. The present CRP and the previous one were initiated and implemented in response to the pressing need to enhance the productivity of economic plants, viz. food crops, fruits and ornamentals. Improvement of crop production has become the highest priority in most countries of Latin America, as in other regions. Breeding superior varieties is often the only feasible solution where inputs are limited; well adapted varieties are required to meet specific agro-environmental conditions. Such varieties provide yield stability on an economically required level. The most important and common factors limiting crop production are abiotic, e.g. cold, salinity, soil aluminium toxicity and drought; as well as biotic, e.g. diseases and pests. Modern biotechnology and induced mutations offer new means and significant potential to breed desired varieties in a relatively short time. Additionally, both approaches facilitate the breeding of some vegetatively propagated crops which until now were improved mainly through selection of rare spontaneous mutants in natural or cultivated populations. Using some of these techniques it recently became possible to produce, in some crops, true-to-type mutated lines or clones within a few months. Biotechnology can also facilitate selection, description and molecular characterization of promising mutants. Currently used DNA markers, such as restriction fragment length polymorphism (RFLP), random amplified polymorphic DNA (RAPD) as well as other polymerase chain reaction (PCR)-based techniques, were included in this CRP to benefit the important crops of this region. Also included in this CRP were doubled haploids (DH), which are obtained from anther or microspore cultures and are very suitable biotechnology methods. In connection with radiation-induced mutations, they can speed up conventional

  20. Induced mutations in connection with biotechnology for crop improvement in Latin America. Proceedings of a final research co-ordination meeting

    International Nuclear Information System (INIS)

    2001-05-01

    This publication results from the second Co-ordinated Research Project (CRP) on Plant Breeding and Genetics organized on a regional basis in Latin America. The present CRP and the previous one were initiated and implemented in response to the pressing need to enhance the productivity of economic plants, viz. food crops, fruits and ornamentals. Improvement of crop production has become the highest priority in most countries of Latin America, as in other regions. Breeding superior varieties is often the only feasible solution where inputs are limited; well adapted varieties are required to meet specific agro-environmental conditions. Such varieties provide yield stability on an economically required level. The most important and common factors limiting crop production are abiotic, e.g. cold, salinity, soil aluminium toxicity and drought; as well as biotic, e.g. diseases and pests. Modern biotechnology and induced mutations offer new means and significant potential to breed desired varieties in a relatively short time. Additionally, both approaches facilitate the breeding of some vegetatively propagated crops which until now were improved mainly through selection of rare spontaneous mutants in natural or cultivated populations. Using some of these techniques it recently became possible to produce, in some crops, true-to-type mutated lines or clones within a few months. Biotechnology can also facilitate selection, description and molecular characterization of promising mutants. Currently used DNA markers, such as restriction fragment length polymorphism (RFLP), random amplified polymorphic DNA (RAPD) as well as other polymerase chain reaction (PCR)-based techniques, were included in this CRP to benefit the important crops of this region. Also included in this CRP were doubled haploids (DH), which are obtained from anther or microspore cultures and are very suitable biotechnology methods. In connection with radiation-induced mutations, they can speed up conventional

  1. Genomic instability in mutation induction on normal human fibroblasts irradiated with chronic low-dose radiations in heavy-ion radiation field

    International Nuclear Information System (INIS)

    Suzuki, M.; Tsuruoka, C.; Uchihori, Y.; Yasuda, H.; Fujitaka, K.

    2003-01-01

    Full text: At a time when manned space exploration is more a reality with the planned the International Space Station (ISS) underway, the potential exposure of crews in a spacecraft to chronic low-dose radiations in the field of low-flux galactic cosmic rays (GCR) and the subsequent biological effects have become one of the major concerns of space science. We have studied both in vitro life span and genomic instability in cellular effects in normal human skin fibroblasts irradiated with chronic low-dose radiations in heavy-ion radiation field. Cells were cultured in a CO2 incubator, which was set in the irradiation room for the biological study of heavy ions in the Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radiological Sciences (NIRS), and irradiated with scattered radiations produced from heavy ions. Absorbed dose measured using a thermoluminescence dosimeter (TLD) and a Si-semiconductor detector was to be around 1.4 mGy per day when operating the HIMAC machine for biological experiments. The total population doubling number (tPDN) of low-dose irradiated cells was significantly smaller (79-93%) than that of unirradiated cells. The results indicate that the life span of the cell population shortens by irradiating with low-dose scattered radiations in the heavy-ion irradiation field. Genomic instability in cellular responses was examined to measure either cell killing or mutation induction in low-dose accumulated cells after exposing to X-ray challenging doses. The results showed that there was no enhanced effect on cell killing between low-dose accumulated and unirradiated cells after exposing to defined challenging doses of 200kV X rays. On the contrary, the mutation frequency on hprt locus of low-dose accumulated cells was much higher than that of unirradiated cells. The results suggested that genomic instability was induced in mutagenesis by the chronic low-dose irradiations in heavy-ion radiation field

  2. Mutation induction by 365-nm radiation and far-ultraviolet light in Escherichia coli differing in near- and far-ultraviolet light sensitivity

    International Nuclear Information System (INIS)

    Leonardo, J.M.; Reynolds, P.R.; Tuveson, R.W.

    1984-01-01

    The his-4 locus derived from Escherichia coli strain AB1157 has been transduced into 4 E. coli strains that exhibit all 4 possible combinations of genes controlling sensitivity to near-ultraviolet light (nur versus nur + ) and far-ultraviolet light (uvrA6 versus uvrA + ). The 4 strains exhibited the predicted sensitivity to 254-nm radiation based on the sensitivity of the parent strains from which they were derived and the frequency of his + mutations predicted from experiments with AB1157 from which the his-4 locus was derived. When the 4 strains were treated with 365-nm radiation, they exhibited the predicted sensitivity based on the near-ultraviolet light sensitivity of the strains from which they were derived while his + mutations were undetectable with the 4 strains as well as with strain AB1157. When treated with 365-nm radiation, cells of a WP2sub(s) strain (a derivative of B/r transduced to his-4) plated on semi-enriched medium prepared with casamino acids did not yield induced mutations, whereas plating on semi-enriched medium prepared with nutrient broth did yield mutants at both the his-4 and trp loci at frequencies at least an order of magnitude lower than that observed with far-ultraviolet light. The induction of nutritionally independent mutants by 365-nm radiation is strongly dependent on the supplement used for semi-enrichment. When compared at equivalent survival levels, mutant frequencies are significantly less following 365-nm radiation when compared with far-ultraviolet radiation. (Auth.)

  3. Environmental modulation of somatic mutations: nature of interactions. Final report, 1 June 1974--31 May 1977

    International Nuclear Information System (INIS)

    Mericle, L.W.

    1977-05-01

    Research on this project has had as a major goal a combined ecologic-genetic investigation of somatic mutations in order to evaluate the impacts of certain changing environmental parameters. The ultimate aim, to better understand how such environmental-mutation interactions operate and to assure the information obtained be extrapolatable to conditions and events in nature. Higher plants delineate reproductive tissues late in development from meristematic, somatic tissues. Moreover, the prevailing method of reproduction may be without sexual fusion of gametes and/or wholly asexual (vegetative). Therefore, somatic mutations can have as far-reaching genetic significance for a plant population as when germ cells, themselves, are directly affected. Our data show diurnal temperature differences (DTD) of greater than or equal to 22.2 C-degrees to be very effective mutagenic agents in the Tradescantia somatic mutation system. Further, these ranges of DTD were found to occur often in important seed production areas. A DTD of 22.2 in magnitude can increase mutations 10-fold. And, durations short as 1-day can induce significant increases in mutation rate. Whether interaction of 22.2 DTD with low-level radiation (800 mR/day) is synergistic or attenuative is still debatable. We believe, however, that spontaneous, and 22.2 DTD induced, mutations occur mainly via the genetic mechanism of somatic crossing-over; mutations from acute ionizing radiation (e.g., 30-60 R γ) via chromosome breakage, producing micronuclei. Requirements for maximizing the Discriminatory Response Capability (DRC) in the Tradescantia somatic mutation system are set forth

  4. A mutation (radA100) in Escherichia coli that selectively sensitizes cells grown in rich medium to X- or U.V.-radiation, or methyl methanesulphonate

    International Nuclear Information System (INIS)

    Diver, W.P.; Sargentini, N.J.; Smith, K.C.

    1982-01-01

    The radA100 mutant was isolated from Escherichia coli K-12 after mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine and selection for gamma radiation sensitivity. The radA100 mutation sensitized stationary phase cells to X-rays if they had been grown in glucose-supplemented rich medium, but not if they had been grown in nonsupplemented rich medium (indicating a defect in glucose-induced resistance). Similarly, logarithmic phase cells were sensitized to X-rays, U.V. radiation and methyl methanesulphonate if they had been grown in rich medium, but not if they had been grown in minimal medium (indicating a defect in medium-dependent resistance). Relative to the wild-type strain, the radA100 mutant was deficient in the repair of X-ray-induced DNA single-strand breaks when grown to logarithmic phase in rich medium, but not when grown in minimal medium. This is a novel mutation amongst the known DNA repair defects in that it did not sensitize logarithmic phase cells, grown in minimal medium, to either X- or U.V.-radiation. (author)

  5. The effects of radiation on p53-mutated glioma cells using cDNA microarray technique

    International Nuclear Information System (INIS)

    Ngo, F.Q.H.; Hsiao, Y.-Y.H.

    2003-01-01

    Full text: In this study, we investigated the effects of 10-Gy irradiation on cell-cycle arrest, apoptosis and clonogenic death in the p53-mutated human U138MG (malignant glioblastoma) cell line. In order to evaluate time-dependent events in cellular responses to radiation, we did a time course study by incubating cells ranging from 0.5 to 48 hours after irradiation. Cell-cycle distribution and apoptosis were evaluated by flow cytometry using propidium iodide (PI) and annexin-V plus PI staining. Cell viability and proliferative capacity were studied by colony formation assay. Dual fluorescence cDNA microarray technique was used to examine the differential expression patterns of the irradiated cells. The cDNA microarray chips used contained DNA sequences corresponding to 12,814 human genes. From the flow cytometry data, it can be observed that radiation induced G2/M phase arrest and that late apoptosis was more evident following G2/M arrest. After 36 hours, some cells underwent senescence and the remains continued on with the cell cycle. Microarray analyses revealed changes in the expression of a small number of cell-cycle-related genes (p21, cyclin B1, etc.) and cell-death genes (tumor necrosis factors, DDB2, etc.) suggesting their involvement in radiation-induced cell-cycle arrest and apoptosis. In silico interpretations of the molecular mechanisms responsible for these radiation effects are in progress

  6. Stimulation of respiration in rat thymocytes induced by ionizing radiation

    International Nuclear Information System (INIS)

    Gudz, T.I.; Pandelova, I.G.; Novgorodov, S.A.

    1994-01-01

    The effect of X irradiation on the respiration of rat thymocytes was studied. An increase in the rate of O 2 uptake was observed 1 h after cells were irradiated with doses of 6-10 Gy. The radiation-induced increase in respiration could be blocked by oligomycin, an inhibitor of mitochondrial ATP synthase, suggesting control by increased cytoplasmic ATP turnover. The stimulation of respiration was not associated with changes in the activity of mitochondrial electron transfer enzymes or permeability of the inner membrane. Several inhibitors of processes which used ATP were screened for their effects on the basal respiration rate and on the radiation response. In irradiated thymocytes, an enhancement of inhibition of respiration by ouabain, La 3+ and cycloheximide was observed. These results indicate that the radiation-induced stimulation of respiration is due to changes in ion homeostasis and protein synthesis. The effect of X irradiation was shown to be independent of the redox status of nonprotein thiols and was not associated with detectable changes in some products of lipid peroxidation. The radiation-induced decrease in activity of superoxide dismutase suggests free radical involvement in deleterious effects of radiation. 43 refs., 2 figs., 3 tabs

  7. Vanguards of paradigm shift in radiation biology. Radiation-induced adaptive and bystander responses

    International Nuclear Information System (INIS)

    Matsumoto, Hideki; Hamada, Nobuyuki; Kobayashi, Yasuhiko; Takahashi, Akihisa; Ohnishi, Takeo

    2007-01-01

    The risks of exposure to low dose ionizing radiation (below 100 mSv) are estimated by extrapolating from data obtained after exposure to high dose radiation, using a linear no-threshold model (LNT model). However, the validity of using this dose-response model is controversial because evidence accumulated over the past decade has indicated that living organisms, including humans, respond differently to low dose/low dose-rate radiation than they do to high dose/high dose-rate radiation. In other words, there are accumulated findings which cannot be explained by the classical ''target theory'' of radiation biology. The radioadaptive response, radiation-induced bystander effects, low-dose radio-hypersensitivity, and genomic instability are specifically observed in response to low dose/low dose-rate radiation, and the mechanisms underlying these responses often involve biochemical/molecular signals that respond to targeted and non-targeted events. Recently, correlations between the radioadaptive and bystander responses have been increasingly reported. The present review focuses on the latter two phenomena by summarizing observations supporting their existence, and discussing the linkage between them from the aspect of production of reactive oxygen and nitrogen species. (author)

  8. Spatiotemporal characterization of ionizing radiation induced DNA damage foci and their relation to chromatin organization

    Energy Technology Data Exchange (ETDEWEB)

    Costes, Sylvain V; Chiolo, Irene; Pluth, Janice M.; Barcellos-Hoff, Mary Helen; Jakob, Burkhard

    2009-09-15

    DNA damage sensing proteins have been shown to localize to the sites of DSB within seconds to minutes following ionizing radiation (IR) exposure, resulting in the formation of microscopically visible nuclear domains referred to as radiation-induced foci (RIF). This review characterizes the spatio-temporal properties of RIF at physiological doses, minutes to hours following exposure to ionizing radiation, and it proposes a model describing RIF formation and resolution as a function of radiation quality and nuclear densities. Discussion is limited to RIF formed by three interrelated proteins ATM (Ataxia telangiectasia mutated), 53BP1 (p53 binding protein 1) and ?H2AX (phosphorylated variant histone H2AX). Early post-IR, we propose that RIF mark chromatin reorganization, leading to a local nuclear scaffold rigid enough to keep broken DNA from diffusing away, but open enough to allow the repair machinery. We review data indicating clear kinetic and physical differences between RIF emerging from dense and uncondensed regions of the nucleus. At later time post-IR, we propose that persistent RIF observed days following exposure to ionizing radiation are nuclear ?scars? marking permanent disruption of the chromatin architecture. When DNA damage is resolved, such chromatin modifications should not necessarily lead to growth arrest and it has been shown that persistent RIF can replicate during mitosis. Thus, heritable persistent RIF spanning over tens of Mbp may affect the transcriptome of a large progeny of cells. This opens the door for a non DNA mutation-based mechanism of radiation-induced phenotypes.

  9. Genomic instability and radiation effects

    International Nuclear Information System (INIS)

    Christian Streffer

    2007-01-01

    Complete text of publication follows. Cancer, genetic mutations and developmental abnormalities are apparently associated with an increased genomic instability. Such phenomena have been frequently shown in human cancer cells in vitro and in situ. It is also well-known that individuals with a genetic predisposition for cancer proneness, such as ataxia telangiectesia, Fanconi anaemia etc. demonstrate a general high genomic instability e.g. in peripheral lymphocytes before a cancer has developed. Analogous data have been found in mice which develop a specific congenital malformation which has a genetic background. Under these aspects it is of high interest that ionising radiation can increase the genomic instability of mammalian cells after exposures in vitro an in vivo. This phenomenon is expressed 20 to 40 cell cycles after the exposure e.g. by de novo chromosomal aberrations. Such effects have been observed with high and low LET radiation, high LET radiation is more efficient. With low LET radiation a good dose response is observed in the dose range 0.2 to 2.0 Gy, Recently it has been reported that senescence and genomic instability was induced in human fibroblasts after 1 mGy carbon ions (1 in 18 cells are hit), apparently bystander effects also occurred under these conditions. The instability has been shown with DNA damage, chromosomal aberrations, gene mutation and cell death. It is also transferred to the next generation of mice with respect to gene mutations, chromosomal aberrations and congenital malformations. Several mechanisms have been discussed. The involvement of telomeres has gained interest. Genomic instability seems to be induced by a general lesion to the whole genome. The transmission of one chromosome from an irradiated cell to an non-irradiated cell leads to genomic instability in the untreated cells. Genomic instability increases mutation rates in the affected cells in general. As radiation late effects (cancer, gene mutations and congenital

  10. Radiation induced degradation of DNA in photodynamic therapy of cancer

    International Nuclear Information System (INIS)

    Ion, Rodica; Scarlat, F.; Niculescu, V.I.R.; Scarlat, Fl.; Gunaydin, Keriman

    2001-01-01

    DNA is a critical cellular target for oxidative processes induced by physical and chemical stresses. It is known that the direct effect of ionizing radiation on DNA results mainly in base ionization and may lead to mutation, carcinogenesis and cell death. The degradation of DNA induced by laser and ionizing radiation (electron and photon beam) is analyzed in this paper. The ionizing radiation degradation of DNA is a radical process. A series of lesions among the major base degradation product has been measured in isolated DNA exposed to gamma radiation in aerated aqueous solution. Degradation can be accounted for by the formation of hydroxyl radicals upon radiolysis of water (indirect effect). The production of DNA damage by ionizing radiation involves two mechanisms, direct and indirect effects. Direct effect leads to ionization and excitation of DNA molecules, while indirect effect is due to the interaction of reactive species, in particular of OH radicals produced by water radiolysis, with targets in DNA. The relative contribution of the two mechanisms in damaging DNA depends on the type of radiation. Single strand breaks and base damage seem to be mainly produced by the attack of hydroxyl radicals on DNA, whereas double strand breaks result predominantly of direct energy deposition. The four bases are degraded in high yield. Direct effect has been mimicked by photo-induced electron abstraction from the bases producing their radical cation. The base damage may also occur from the formation of radical cation of purine and pyrimidine components. When DNA is irradiated in solution, single strand breaks are mainly due to the abstraction of an H atom from the 4 ' position of 2 ' -deoxyribose by the attack of OH radicals produced by water radiolysis. Quantification of the modified bases showed the guanine is the preferential target. Ionizing radiation induces several types of DNA modifications, including chain breaks, DNA-protein cross-links, oxidized DNA bases

  11. The studies on radiation mutation breeding of Bacillus subtilis with high-yield of amylase

    International Nuclear Information System (INIS)

    Chen Xiaoming; Zhang Liang; Zhang Jianguo; Zhou Liwei

    2008-01-01

    The mutagenesis effects on the yield of amylase have been investigated with Bacillus subtilis irradiated by γ-rays and fast neutrons in once or twice irradiation at various dose rates and total irradiation doses. Several parameters such as flat transparent circle, colony diameter, transparent circle diameter and the ratio of flat transparent circle to colony diameter (HC) are used to estimate the radiation mutation of Bacillus subtilis. A series of results has been obtained as (1) Irradiation both with neutrons and γ-rays could make Bacillus subtilis mutationed to produce high-yield amylase effectively. (2) The average colony diameter of Bacillus subtilis irradiated by γ-rays or fast neutrons is smaller than that of control group at various total doses and dose rates. And their colony diameter becomes smaller slightly with the increment of γ-rays irradiation dose. (3) After the second neutrons irradiation, the values of average colony diameter, the biggest colony diameter, average transparent circle diameter and the biggest transparent circle diameter of all mutationed Bacillus subtilis exceed that of original strains greatly. (4) Three kinds of mutationed Bacillus subtilis strains with high-yield amylase have been screened out, in which two strains can produce high-yield amylase steadily after 15 times breeding. Their biggest colony diameter, the biggest transparent circle diameter and the biggest HC value are up to 8.32 mm, 22.38 mm and 5.39 respectively. (authors)

  12. An integrated model for radiation induced cancer

    International Nuclear Information System (INIS)

    Hall, E.J.; Varma, M.

    1994-01-01

    Risk estimates for radiation induced cancer are based on epidemiological data, principally the Japanese A bomb survivors. These estimates for radiation are better known than for any other environmental pollutant, but they do not relate directly to exposure to low doses and low dose rate. Recent rapid advances in molecular genetics, coupled with steady gains in cellular biology, radiation physics and chemistry led to the notion that the time may not be far off when it may be possible to arrive at human cancer risk estimates entirely from laboratory data. Whether risk estimates based on laboratory data will ever replace estimates based on epidemiological studies is an open question. What is clear is that laboratory data can supplement the present risk estimates by providing information on the relative effectiveness of high LET radiations, the importance of dose rate and dose protraction, and by identifying subpopulations which are unusually sensitive or resistant to radiation carcinogenesis. (author)

  13. Induction of lethal mutations in the x-chromosome of unirradiated Drosophila oocytes after fertilization by irradiated spermatozoa

    International Nuclear Information System (INIS)

    Shaposhnikov, M.V.; Zainullin, V.G.

    2003-01-01

    Full text: In primary study on Drosophila it was found that irradiated male X-chromosomes induce recessive lethals in unirradiated female homologues (Abeleva et al., 1961, Radiobiologya. 1:123-126). The same effects were obtained in Drosophila in some recent investigations. The mechanisms of these effects is unknown. However it may be responsible for low-dose radiation effects as it induce mutations in unirradiated DNA. We assume that this effect may be a result of activation of error prone repair in response to preliminary DNA lesions in irradiated chromosome. In this research we analyse the frequencies of the recessive lethal mutations in the X-chromosome of Drosophila females mated with irradiated Basc males. We used acute irradiation with a dose rate of 10 Gy. For testing our hypothesis we use the mus209 and mei-41 mutant females. Mus209 is a PCNA gene homologue and mei-41 is a homologue of ATM gene. These genes are involved in post-replication DNA repair which may be error prone repair in Drosophila. It was obtained the tendency to decreasing the mutation rate at the mei-41[D5] background and decreasing mutation rate in mus209[B1] background in comparison with wild type strains CS (p<0.05). The obtained results demonstrate the possible role of mus209[B1] and mei-41[D5] genes in the inducing of mutations in the unirradiated X-chromosome in the presence of irradiated homologue

  14. Induced mutations for resistance to leaf rust in wheat

    International Nuclear Information System (INIS)

    Borojevic, K.

    1983-01-01

    Problems related to the induction of mutations for disease resistance were investigated under several aspects, using the wheat/leaf rust system. Previously selected mutant lines, tested in M 11 and M 13 , were found to differ with regard to infection type and disease severity from the original varieties. To verify the induced-mutation origin, these mutants were examined further using test crosses with carriers of known genes for leaf rust resistance and electrophoresis. A separate experiment to induce mutations for leaf rust resistance in the wheat varieties Sava, Aurora and Siete Cerros, using gamma rays, fast neutrons and EMS, yielded mutants with different disease reaction in the varieties Sava and Aurora at a frequency of about 1x10 - 3 per M 1 plant progenies. (author)

  15. Involvement of DNA-PK and ATM in radiation- and heat-induced DNA damage recognition and apoptotic cell death

    International Nuclear Information System (INIS)

    Tomita, Masanori

    2010-01-01

    Exposure to ionizing radiation and hyperthermia results in important biological consequences, e.g. cell death, chromosomal aberrations, mutations, and DNA strand breaks. There is good evidence that the nucleus, specifically cellular DNA, is the principal target for radiation-induced cell lethality. DNA double-strand breaks (DSBs) are considered to be the most serious type of DNA damage induced by ionizing radiation. On the other hand, verifiable mechanisms which can lead to heat-induced cell death are damage to the plasma membrane and/or inactivation of heat-labile proteins caused by protein denaturation and subsequent aggregation. Recently, several reports have suggested that DSBs can be induced after hyperthermia because heat-induced phosphorylated histone H2AX (γ-H2AX) foci formation can be observed in several mammalian cell lines. In mammalian cells, DSBs are repaired primarily through two distinct and complementary mechanisms: non-homologous end joining (NHEJ), and homologous recombination (HR) or homology-directed repair (HDR). DNA-dependent protein kinase (DNA-PK) and ataxia-telangiectasia mutated (ATM) are key players in the initiation of DSB repair and phosphorylate and/or activate many substrates, including themselves. These phosphorylated substrates have important roles in the functioning of cell cycle checkpoints and in cell death, as well as in DSB repair. Apoptotic cell death is a crucial cell suicide mechanism during development and in the defense of homeostasis. If DSBs are unrepaired or misrepaired, apoptosis is a very important system which can protect an organism against carcinogenesis. This paper reviews recently obtained results and current topics concerning the role of DNA-PK and ATM in heat- or radiation-induced apoptotic cell death. (author)

  16. Effect of epicatechin against radiation-induced oral mucositis: in vitro and in vivo study.

    Directory of Open Access Journals (Sweden)

    Yoo Seob Shin

    Full Text Available PURPOSE: Radiation-induced oral mucositis limits the delivery of high-dose radiation to head and neck cancer. This study investigated the effectiveness of epicatechin (EC, a component of green tea extracts, on radiation-induced oral mucositis in vitro and in vivo. EXPERIMENTAL DESIGN: The effect of EC on radiation-induced cytotoxicity was analyzed in the human keratinocyte line HaCaT. Radiation-induced apoptosis, change in mitochondrial membrane potential (MMP, reactive oxygen species (ROS generation and changes in the signaling pathway were investigated. In vivo therapeutic effects of EC for oral mucositis were explored in a rat model. Rats were monitored by daily inspections of the oral cavity, amount of oral intake, weight change and survival rate. For histopathologic evaluation, hematoxylin-eosin staining and TUNEL staining were performed. RESULTS: EC significantly inhibited radiation-induced apoptosis, change of MMP, and intracellular ROS generation in HaCaT cells. EC treatment markedly attenuated the expression of p-JNK, p-38, and cleaved caspase-3 after irradiation in the HaCaT cells. Rats with radiation-induced oral mucositis showed decreased oral intake, weight and survival rate, but oral administration of EC significantly restored all three parameters. Histopathologic changes were significantly decreased in the EC-treated irradiated rats. TUNEL staining of rat oral mucosa revealed that EC treatment significantly decreased radiation-induced apoptotic cells. CONCLUSIONS: This study suggests that EC significantly inhibited radiation-induced apoptosis in keratinocytes and rat oral mucosa and may be a safe and effective candidate treatment for the prevention of radiation-induced mucositis.

  17. Injury of the blood-testies barrier after low-dose-rate chronic radiation exposure

    Energy Technology Data Exchange (ETDEWEB)

    Sohn, Young Hoon; Bae Min Ji; Lee, Chang Geun; Yang, Kwang Mo; Jur, Kyu; Kim, Jong Sun [Dongnam Institute of Radiological and Medical Science, Busan (Korea, Republic of)

    2014-04-15

    The systemic effect of radiation increases in proportionally with the dose and dose rate. Little is known concerning the relationships between harmful effects and accumulated dose, which is derived from continuous low-dose rate radiation exposure. Recent our studies show that low-dose-rate chronic radiation exposure (3.49 mGy/h) causes adverse effects in the testis at a dose of 2 Gy (6 mGy/h). However, the mechanism of the low-dose-rate 2 Gy irradiation induced testicular injury remains unclear. The present results indicate that low-dose rate chronic radiation might affect the BTB permeability, possibly by decreasing levels of ZO-1, Occludin-1, and NPC-2. Furthermore, our results suggest that there is a risk of male infertility through BTB impairment even with low-dose-rate radiation if exposure is continuous.

  18. Analysis of time of death of prenatally lethal Steeloid mutations

    International Nuclear Information System (INIS)

    Rinchik, E.M.; Cummings, C.C.; Bangham, J.W.; Hunsicker, P.R.; Phipps, E.L.; Stelzner, K.F.

    1987-01-01

    Deletion mutations have been extremely useful in initiating the functional and molecular dissections of regions of the mouse genome. For the d-se and c regions, for example, it was observed that radiation mutations carrying lethal factors separable, by complementation analysis, from the primary d, se, or c mutation itself, could often be associated at both the genetic and molecular levels with multilocus chromosomal deletions. Since many of the Oak Ridge Sld mutations arose in radiation mutagenesis experiments, a substantial number may carry chromosomal deletions that involve the Sl locus in chromosome 10. Because of the great value of deletion mutations for the genetic and molecular analysis of chromosomal regions and complex genetic loci, they have initiated a series of experiments designed to test whether radiation-induced Sld mutations carry other lethal factors, in addition to the lethality caused by severe alleles of the Sl locus itself, as one prescreen for identifying Sld's that are caused by deletions

  19. Rapid screening of spontaneous and radiation-induced structural changes at the vestigial gene of Drosophila melanogaster by polymerase chain reaction

    International Nuclear Information System (INIS)

    Aleksandrov, I.D.; Lapidus, I.L.; Aleksandrova, M.V.; Karpovskij, A.L.; Korablinova, S.V.; Levkovich, N.V.

    1998-01-01

    A total of 27 independent isolated spontaneous and gamma-ray-induced heritable mutations at the vestigial gene of Drosophila melanogaster were analysed by a rapid deletion screening method with polymerase chain reaction (PCR) amplification. According to the results obtained 36.4% (4 of 11) of spontaneous mutants and 62.5% (10 of 16) of gamma-ray-induced ones have revealed deficiency of one or more fragments studied. The rest of spontaneous and radiation mutants showed no alterations in the PCR patterns, indicating possible small scale changes (point mutations) inside the gene region studied or, probably, the gross lesions situated elsewhere. The distribution of the mutation damages in the gene region studied are discussed

  20. Radiation-induced mucositis pain in laryngeal cancer

    International Nuclear Information System (INIS)

    Takahashi, Atsuhito; Shoji, Kazuhiko; Iki, Takehiro; Mizuta, Masanobu; Matsubara, Mami

    2009-01-01

    Radiation therapy in those with head and neck malignancies often triggers painful mucositis poorly controlled by nonsteroidal antiinflammatory drugs (NSAIDs). To better understand how radiation-induced pain develops over time, we studied the numerical rating scale (NRS 0-5) pain scores from 32 persons undergoing radiation therapy of 60-72 Gy for newly diagnosed laryngeal cancer. The degree of mucositis was evaluated using Common Terminology Criteria for Adverse Events version3.0 (CTCAE v3.0). We divided the 32 into a conventional fractionation (CF) group of 14 and a hyperfractionation (HF) group of 18, and further divided laryngeal cancer into a small-field group of 23 and a large-field group of 9. The mucositis pain course was similar in CF and HF, but mucositis pain was severer in the HF group, which also required more NSAIDs. Those in the large-field group had severer pain and mucositis and required more NSAIDs than those in the small-field group. We therefore concluded that small/large-field radiation therapy, rather fractionation type, was related to the incidence of radiation-induced mucositis pain. (author)

  1. Delayed repair of radiation induced clustered DNA damage: Friend or foe?

    International Nuclear Information System (INIS)

    Eccles, Laura J.; O'Neill, Peter; Lomax, Martine E.

    2011-01-01

    A signature of ionizing radiation exposure is the induction of DNA clustered damaged sites, defined as two or more lesions within one to two helical turns of DNA by passage of a single radiation track. Clustered damage is made up of double strand breaks (DSB) with associated base lesions or abasic (AP) sites, and non-DSB clusters comprised of base lesions, AP sites and single strand breaks. This review will concentrate on the experimental findings of the processing of non-DSB clustered damaged sites. It has been shown that non-DSB clustered damaged sites compromise the base excision repair pathway leading to the lifetime extension of the lesions within the cluster, compared to isolated lesions, thus the likelihood that the lesions persist to replication and induce mutation is increased. In addition certain non-DSB clustered damaged sites are processed within the cell to form additional DSB. The use of E. coli to demonstrate that clustering of DNA lesions is the major cause of the detrimental consequences of ionizing radiation is also discussed. The delayed repair of non-DSB clustered damaged sites in humans can be seen as a 'friend', leading to cell killing in tumour cells or as a 'foe', resulting in the formation of mutations and genetic instability in normal tissue.

  2. Sucrose and IQ induced mutations in rat colon by independent

    DEFF Research Database (Denmark)

    Hansen, Max; Hald, M. T.; Autrup, H.

    2004-01-01

    Sucrose-rich diets have repeatedly been observed to have co-carcinogenic actions in colon and liver of rats and to increase the number of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) induced aberrant crypt foci in rat colon. To investigate a possible interaction between sucrose and IQ...... on the genotoxicity in rat liver and colon, we gave Big Blue rats(TM) a diet containing sucrose (0%, 3.45% or 13.4% w/w) and/or IQ (70 ppm) for a period of 3 weeks. Sucrose and IQ increased the mutation frequency in the colon. The effect of combined treatments with IQ and sucrose on the mutation frequencies...... was additive indicating that sucrose and IQ act independently. This was supported by the mutation spectra where sucrose expands the background mutations in the colon, whereas IQ, in other studies, more specifically has induced G:C --> T:A transversions. In the liver IQ increased the mutation frequency, whereas...

  3. Germline mutation rates at tandem repeat loci in DNA-repair deficient mice

    International Nuclear Information System (INIS)

    Barber, Ruth C.; Miccoli, Laurent; Buul, Paul P.W. van; Burr, Karen L.-A.; Duyn-Goedhart, Annemarie van; Angulo, Jaime F.; Dubrova, Yuri E.

    2004-01-01

    Mutation rates at two expanded simple tandem repeat (ESTR) loci were studied in the germline of non-exposed and irradiated severe combined immunodeficient (scid) and poly(ADP-ribose) polymerase (PARP-1 -/- ) deficient male mice. Non-exposed scid and PARP -/- male mice showed considerably elevated ESTR mutation rates, far higher than those in wild-type isogenic mice and other inbred strains. The irradiated scid and PARP-1 -/- male mice did not show any detectable increases in their mutation rate, whereas significant ESTR mutation induction was observed in the irradiated wild-type isogenic males. ESTR mutation spectra in the scid and PARP-1 -/- strains did not differ from those in the isogenic wild-type strains. Considering these data and the results of previous studies, we propose that a delay in repair of DNA damage in scid and PARP-1 -/- mice could result in replication fork pausing which, in turn, may affect ESTR mutation rate in the non-irradiated males. The lack of mutation induction in irradiated scid and PARP-1 -/- can be explained by the high cell killing effects of irradiation on the germline of deficient mice

  4. Optimal mutation rates for the (1+λ) EA on OneMax

    DEFF Research Database (Denmark)

    Gießen, Christian; Witt, Carsten

    2016-01-01

    We study the (1 + λ) EA with mutation probability c/n, where c > 0 is a constant, on the ONEMAX problem. Using an improved variable drift theorem, we show that upper and lower bounds on the expected runtime of the (1+λ) EA obtained from variable drift theorems are at most apart by a small lower...... mutation rates for the (1+λ) EA for various parameter settings of c and λ and also for moderate sizes of n. This makes the need for potentially lengthy and costly experiments in order to optimize the parameters unnecessary. Interestingly, even for moderate n and not too small λ it turns out that mutation...... rates up to 10% larger than the asymptotically optimal rate 1/n minimize the expected runtime. However, in absolute terms the expected runtime does not change by much when replacing 1/n with the optimal mutation rate....

  5. Radiation induced skeletal changes in beagle: dose rates, dose, and age effect analysis from 226Ra

    International Nuclear Information System (INIS)

    Momeni, M.H.; Williams, J.R.; Rosenblatt, L.S.

    1976-01-01

    Radiation-induced skeletal injury (E) and the rate of skeletal injury were studied as a function of time and dose in beagles administered 226 Ra Cl 2 in eight semimonthly iv injections starting at 2, 4, or 14 months of age. Skeletal changes were evaluated with a radiographic x-ray scoring system in 20 skeletal regions; each region was scored on a 0 to 6 scale. Bone changes in six regions of humeri were qualitatively analyzed for comparison with total skeletal changes. Skeletal changes were classified by endosteal or periosteal cortical sclerosis and thickening, fractures, osteolytic lesions, and trabecular coarsening

  6. Rooting, growth, and color mutation of poinsettias affected by gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun Kyung; Kim, Won Hee; Kim, Seung Tae [National Institute of Horticultural and Herbal Science, RDA, Suwon (Korea, Republic of); Kang, Si Yong [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2010-09-15

    This experiment was carried out to investigate the effects of gamma-radiation on the rooting, growth, and color mutation in poinsettia. Using 10 poinsettia varieties ('Lollipop', 'Little Peace', 'Happy Day', 'Early Bird', 'Pixy Red', 'Happy Time', 'Heidi', 'Red Bell', 'Clara', and 'Scarlet') bred by National Institute of Horticultural and Herbal Science, 100 Gy of gamma ray was irradiated at the stage of callused cuttings. Four weeks after sticking cuttings in the rooting media, 8 cultivars showed 100% of root formation, but 'Early Bird' rooted 24.4% and even died off during the cutting propagation. After planting rooted cuttings, survival rate until flowering time varied among irradiated cultivars. While 'Pixy Red' and 'Heidi' survived about 98%, 'Clara', 'Happy Day', and 'Early Bird' survived lesser than 30%. All irradiated plants showed remarkably shorter plant height, lesser branch numbers than non-irradiated control plants. Thirty color mutants were obtained among 281 plants survived until flowering time. Nine were complete color mutated branches, whereas 21 mutants were partially color mutated bracts and transitional leaves. Color patterns mutated by 100 Gy of gamma ray were divided into pink, hot pink, light red and spotted (pink spots with red main color). Pink mutants were commonly obtained. Complete color mutants were discovered from 4 plants of 'Pixy Red', 2 plants of 'Red Bell' and 3 plants of Lollipop.

  7. Genetics and ionizing radiations. 2. The genetic effects of ionizing radiations

    International Nuclear Information System (INIS)

    Dutrillaux, B.

    1980-01-01

    Ionizing radiations are the best known mutagenic agents. Their relative importance as compared to other mutagens cannot be determined. Experiments show that male germinal cells are more sensitive than female germinal cells. This sensitivity is determined by the cell phase at the time of agression. Acute X-exposure results in a mutation rate of about 1.7x10 -7 rad -1 per gamete and per gene in the male. This rate is lower in case of chronic exposure. Pathological effects will appear in the first (dominant genes, and unbalanced chromosomal anomalies) or n-th generation (recessive genes and balanced chromosomal rearrangements). Direct studies on humans have brought contradictory results. Only X or γ-emitters induce a true genetic risk, the other radiations being too little penetrating to reach the gonads. The doubling dose of the mutation rate is estimated at over 100 rad in males and over 1,000 rad in females. However, one cannot conclude that low doses are not harmless because their effects are difficult to demonstrate. The individual risk, that remains low, must be distinguished from the collective risk for which the safeguard of the quality of the genetic material of our species must remain our prime purpose [fr

  8. Laser radiation effect on radiation-induced defects in heavy ion tracks in dielectrics

    International Nuclear Information System (INIS)

    Egorov, A.N.; Zhiryakov, B.M.; Kushin, V.V.; Lyapidevskij, V.K.; Khokhlov, N.B.

    1988-01-01

    Possibility of laser radiation resonance effect on radiation-induced defects in heavy ion tracks in dielectric materials is investigated. Absorption spectra in infrared, visible and ultraviolet ranges for cellulose nitrate samples irradiated by 6 MeV/nucleon 58 Ni ions and reactor gamma radiation are measured. Absorption spectra for irradiated and reference samples are presented. Two absorption bands λ 1 =0.33 μm (E 1 =3.9 eV) and λ 2 =0.72 μm (E 2 =1.7 eV) are detected. Etching rate decrease in a track under laser radiation effect is noticed. 3 refs.; 1 fig

  9. Morphogenesis of the radiation-induced mutant limb deformity (ld) of the common mouse

    International Nuclear Information System (INIS)

    Selow, J.; Win