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Journal Articles

Mutational effects of different LET radiations in ${it rpsL}$ transgenic ${it Arabidopsis}$

Yoshihara, Ryohei; Hase, Yoshihiro; Sato, Ryohei*; Takimoto, Koichi*; Narumi, Issei

International Journal of Radiation Biology, 86(2), p.125 - 131, 2010/02

 Times Cited Count:18 Percentile:79.59(Biology)

In an effort to assess the characteristics of mutation induced by different LET radiation in higher plants, the mutational effects of carbon-ion beams and $$gamma$$-rays were investigated in ${it Arabidopsis}$. The ${it rpsL}$ transgenic ${it Arabidopsis}$ (Arabidopsis/rpsL) mutation detection system was adopted. Dry seeds of Arabidopsis/rpsL were irradiated with $$gamma$$-rays and 208-MeV carbon ions (208-MeV $$^{12}$$C$$^{5}$$), and the mutation frequency and mutation spectrum were examined. Our result suggested that 208-MeV $$^{12}$$C$$^{5}$$ and $$gamma$$-rays induced different mutational effects in ${it Arabidopsis}$ dry seed.

Journal Articles

Silencing of CPD photolyase makes ${it Arabidopsis}$ hypersensitive and hypermutable in response to UV-B radiation

Yoshihara, Ryohei; Nakane, Chiyoko*; Sato, Ryohei*; Yasuda, Ai*; Takimoto, Koichi*

Genes and Environment, 30(2), p.53 - 61, 2008/05

We generated a CPD photolyase knock-down in ${it Arabidopsis thaliana}$ by RNAi to investigate the role of CPD photorepair for protection of plants from solar UV. These knock-down lines exhibited hypersensitivity to UV-B and an increased occurrence of mutation induced by UV-B radiation compared with ${it Arabidopsis}$ proficient in CPD photolyase. These results indicate that CPD photoreactivation plays an important role for UV resistance of ${it Arabidopsis}$ and suppression of UV-induced mutagenesis.

Oral presentation

Mutation analysis using ${it rpsL}$ gene in plant

Yoshihara, Ryohei; Yasuda, Ai*; Sato, Ryohei*; Hase, Yoshihiro; Narumi, Issei; Takimoto, Koichi*

no journal, , 

no abstracts in English

Oral presentation

The Importance of photorepair for plant UV protection and UV induced mutagenesis

Sato, Ryohei*; Yasuda, Ai*; Yoshihara, Ryohei; Takimoto, Koichi*

no journal, , 

no abstracts in English

Oral presentation

Analysis on mutation induced by ion-beam and $$gamma$$-rays in ${it Arabidopsis}$

Yoshihara, Ryohei; Hase, Yoshihiro; Takimoto, Koichi*; Narumi, Issei

no journal, , 

Ionizing radiation induces DNA damages which cause mutation. Organisms have DNA repair systems to repair DNA damages. The relationship between types of mutation induced by ionizing radiation and DNA repair systems are well studied in bacteria and animal. In plant, however, little is known about it. In this study we will investigate ion-beam and $$gamma$$-rays induced mutations in plant by using ${it Arabidopsis}$ mutation detection system (Yoshihara et al. 2006). Ion-beam and $$gamma$$-rays are irradiated to ${it Arabidopsis}$ containing ${it E. coli rpsL}$ gene. Mutated ${it rpsL}$ gene is collected as a plasmid by plasmid rescue from chromosomal DNA and analyze the types of mutations. We will report the results of ion-beam and $$gamma$$-rays induced mutations detected by this system.

Oral presentation

Analysis of mutation spectrum induced by carbon ions and $$gamma$$-rays in higher plant

Yoshihara, Ryohei; Hase, Yoshihiro; Takimoto, Koichi*; Narumi, Issei

no journal, , 

Mutation spectrum induced by 220 MeV Carbon ion beam (220 MeV C), $$gamma$$-rays and Carbon ion near the Bragg peak in ${it Arabidopsis}$ seed was determined. Mutant frequency was increased by 220 MeV C and $$gamma$$-rays irradiation. 220 MeV C and $$gamma$$-rays induced G:C to A:T transition and deletion efficiently. 220 MeV C induced higher incidence of complex type of mutation. Frameshift mutation in $$gamma$$-rays irradiated seed was frequent, but it was background level in 220 MeV C irradiated seed. These difference of mutation spectrum might be caused by the difference of DNA damage formed by 220 MeV C and $$gamma$$-rays irradiation. Mutant frequency in seed exposed to carbon ion near the Bragg peak was not increased. The fluence of carbon ion near the Bragg peak was lower because it has higher cell killing effect. The fluence of carbon ion might be too low to detect mutation in target gene.

Oral presentation

Mutation induced by ionizing radiation in higher plant

Yoshihara, Ryohei; Hase, Yoshihiro; Takimoto, Koichi*; Narumi, Issei

no journal, , 

We analyzed mutation induced by 220 MeV C$$^{5+}$$, $$gamma$$-rays and carbon ions near the Bragg peak in ${it Arabidopsis}$ seed. Mutations were detected by ${it rpsL}$ transgenic ${it Arabidopsis}$ mutation detection system. Although mutant frequency was increase with 220 MeV C$$^{5+}$$ or $$gamma$$-rays, that was background level in ${it Arabidopsis}$ irradiated carbon ion near the Bragg peak. The fluence of carbon ion near the Bragg peak was lower because it has higher cell killing effect. The fluence was too low to detect mutation by this method.

Oral presentation

Radiation-induced mutation in seeds and seedlings of ${it Arabidopsis}$

Yoshihara, Ryohei; Hase, Yoshihiro; Takimoto, Koichi*; Narumi, Issei

no journal, , 

To analyze mutagenic effects of ionizing radiation in higher plant, seeds of transgenic Arabidopsis carrying ${it rpsL}$ gene were irradiated with carbon ions and $$gamma$$-rays. Mutation spectrum showed that the carbon ions and $$gamma$$-rays frequently induced G$$rightarrow$$A and deletions. In addition, the carbon ions induced complex-type mutations and the $$gamma$$-rays induced frameshift mutations with relatively higher frequency. The G$$rightarrow$$T and A$$rightarrow$$C, which are caused by oxidized guanine, were hardly found in our experiment. Carbon ions near the Bragg peak had higher lethal effect pet unit dose than the carbon ions that penetrates the seeds. However, mutant frequency was remained at control level. The ${it rpsL}$ mutation analysis system only detects intragenic mutations, our result suggests that the carbon ions near the Bragg peak seldom induce intragenic mutations in the Arabidopsis dry seeds.

Oral presentation

Analysis of mutational effects by radiation in higher plant

Yoshihara, Ryohei; Hase, Yoshihiro; Nozawa, Shigeki; Takimoto, Koichi*; Narumi, Issei

no journal, , 

We irradiated carbon ion-beams (220-MeV C) and $$gamma$$-rays to ${it Arabidopsis}$ carrying ${it rpsL}$ gene to analyze mutational effects of these radiations. Our results suggested that $$gamma$$-rays might induce smaller size of deletion mutation compared to 220-MeV C. The induction of oxidized guanine by these radiations was low in dry seeds because of low incidence of G:C to T:A and A:T to C:G transversion in irradiated group. $$gamma$$-ray-induced mutation analysis in ${it Arabidopsis}$ seedling was similar to that in dry seed, suggesting the mutational effect of radiation used here in higher plant might be different from that in other organisms.

Oral presentation

Estimation of DNA damage induced by ionizing radiation in Arabidopsis M1 plant; Intragenic mutation analysis using the Arabidopsis/rpsL system

Yoshihara, Ryohei; Hase, Yoshihiro; Sakamoto, Ayako; Nozawa, Shigeki; Takimoto, Koichi*; Narumi, Issei

no journal, , 

no abstracts in English

Oral presentation

Mutational effects of UV and ionizing radiations in higher plants; Mutation spectrum analysis using ${it Arabidopsis thaliana}$

Yoshihara, Ryohei; Takimoto, Koichi*; Hase, Yoshihiro; Nozawa, Shigeki; Sakamoto, Ayako; Narumi, Issei

no journal, , 

We constructed a mutation detection system by integrating a linearized plasmid DNA that has ${it Escherichia coli rpsL}$ gene into the chromosomal DNA of ${it Arabidopsis thaliana}$. We first analyzed the UV-induced mutation spectrum. The frequency of G to A transitions was increased after the exposure to UV light. To evaluate the effects of photorepair activity for CPDs in maintaining genomic integrity, we constructed RNAi plants in which the expression of CPD photolyase was suppressed. The mutation spectrum analysis in the RNAi plants showed that the frequency of frameshift mutations was increased together with that of G to A transitions. This suggests that the suppression of CPD photorepair not only increase the typical base substitutions but also other kinds of mutations. We next analyzed the mutation spectrum induced by $$gamma$$ rays and carbon-ion beams (LET 121.5 keV/$$mu$$m). The results showed that $$gamma$$ rays tended to induce shorter size of deletions than the carbon ions.

Oral presentation

Effect of oxidative DNA damage on radiation-induced mutagenesis in ${it Arabidopsis thaliana}$

Yoshihara, Ryohei; Hase, Yoshihiro; Nozawa, Shigeki; Narumi, Issei; Takimoto, Koichi*; Hidema, Jun*; Sakamoto, Ayako

no journal, , 

We analyzed $$gamma$$-ray-induced mutation spectrum in Arabidopsis seedling to investigate the effect of oxidative DNA damage on mutagenesis. Moreover, to evaluate the effect of nucleotide pool sanitization system on $$gamma$$-ray-induced mutations, we analyzed a mutant deficient in the Arabidopsis ${it NUDT1}$ gene that is a homologue of ${it mutT}$. The $$gamma$$-ray sensitivity of the ${it NUDT1}$ mutant was slightly higher, but not statistically significant, than that of wild type plant. However, the mutation spectra induced by $$gamma$$-rays were different between the wild type and ${it NUDT1}$ plants. From these results, it was suggested that the ${it NUDT1}$ deficiency obviously affects on the mutagenesis but not the plant growth following $$gamma$$-irradiation.

Oral presentation

Mutation spectrum analysis in higher plants

Yoshihara, Ryohei; Hase, Yoshihiro; Nozawa, Shigeki; Narumi, Issei; Takimoto, Koichi*; Sakamoto, Ayako

no journal, , 

Oral presentation

Development of treatment for low radioactive effluent in Tokai Reprocessing Plant, 14; Study of Cs/Sr adsorption process by two linked column experiment

Takano, Masato; Ito, Yoshiyuki; Suzuki, Tatsuya*; Takimoto, Mayumi*; Matsukura, Minoru*; Mimura, Hitoshi*; Mori, Koichi*; Iwasaki, Mamoru*

no journal, , 

no abstracts in English

14 (Records 1-14 displayed on this page)
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