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Evaluation of DNA Damage Using Microwave Dielectric Absorption Spectroscopy
Hirayama, Makoto,Matuo, Youichirou,Sunagawa, Takeyoshi,Izumi, Yoshinobu The Korean Association for Radiation Protection 2016 방사선방어학회지 Vol.41 No.4
Background: Evaluation of deoxyribonucleic acid (DNA)-strand break is important to elucidate the biological effect of ionizing radiations. The conventional methods for DNA-strand break evaluation have been achieved by Agarose gel electrophoresis and others using an electrical property of DNAs. Such kinds of DNA-strand break evaluation systems can estimate DNA-strand break, according to a molecular weight of DNAs. However, the conventional method needs pretreatment of the sample and a relatively long period for analysis. They do not have enough sensitivity to detect the strand break products in the low-dose region. Materials and Methods: The sample is water, methanol and plasmid DNA solution. The plasmid DNA pUC118 was multiplied by using Escherichia coli JM109 competent cells. The resonance frequency and Q-value were measured by means of microwave dielectric absorption spectroscopy. When a sample is located at a center of the electric field, resonance curve of the frequency that existed as a standing wave is disturbed. As a result, the perturbation effect to perform a resonance with different frequency is adopted. Results and Discussion: The resonance frequency shifted to higher frequency with an increase in a concentration of methanol as the model of the biological material, and the Q-value decreased. The absorption peak in microwave power spectrum of the double-strand break plasmid DNA shifted from the non-damaged plasmid DNA. Moreover, the sharpness of absorption peak changed resulting in change in Q-value. We confirmed that a resonance frequency shifted to higher frequency with an increase in concentration of the plasmid DNA. Conclusion: We developed a new technique for an evaluation of DNA damage. In this paper, we report the evaluation method of DNA damage using microwave dielectric absorption spectroscopy.
Microwave Dielectric Absorption Spectroscopy Aiming at Novel Dosimetry Using DNAs
Izumi, Yoshinobu,Hirayama, Makoto,Matuo, Youichirou,Sunagawa, Takeyoshi The Korean Association for Radiation Protection 2017 방사선방어학회지 Vol.42 No.1
Background: We are developing L-band and S-band microwave dielectric absorption systems aiming novel dosimetry using DNAs, such as plasmid DNA and genomic DNA, and microwave technology. Materials and Methods: Each system is composed of a cavity resonator, analog signal generator, circulator, power meter, and oscilloscope. Since the cavity resonator is sensitive to temperature change, we have made great efforts to prevent the fluctuation of temperature. We have developed software for controlling and measurement. Results and Discussion: By using this system, we can measure the resonance frequency, f, and ${\Delta}Q$ (Q is a dimensionless parameter that describes how under-damped an oscillator or resonator is, and characterizes a resonator's bandwidth relative to its center frequency) within about 3 minutes with high accuracy. Conclusion: This system will be expected to be applicable to DNAs evaluations and to novel dosimetric system.
CELL MORPHOLOGY CHANGE BY THE ULTRAVIOLET RAY IRRADIATION
Park, Myoung-Joo,Matuo, Yoichirou,Akiyama, Yoko,Izumi, Yoshinobu,Nishijima, Shigehiro The Korean Association for Radiation Protection 2009 방사선방어학회지 Vol.34 No.1
The effect of low doses of ultraviolet (UV) irradiation on morphology changes of cell has been studied based on the observation of the cell length. It was shown that UV-irradiated cell has different behavior in comparison with non-irradiated cell. From the histogram of cell-length distribution, it was confirmed that cell cycle of non irradiated cell was 28 hours, and that cell cycle of irradiated cell with dose of $20\;Jm^{-2}$ was delayed (39 hours), while irradiated cell with $40\;Jm^{-2}$ and $60\;Jm^{-2}$ did not divide and kept growing continuously. It was supposed that in case of $20\;Jm^{-2}$ of irradiation dose, the cell cycle was delayed because the checkpoint worked in order to repair DNA damage induced by generation of pyrimidine dimer, reactive oxygen species and so on. It was also supposed that in case of $40\;Jm^{-2}$ and $60\;Jm^{-2}$ of irradiation dose, overgrowth was induced because the checkpoint was not worked well. The morphology of overgrown cell was similar to that of normally senescent cell. Therefore, it was considered that cell senescence was accelerated by UV irradiation with irradiation doses of $40\;Jm^{-2}$ and $60\;Jm^{-2}$.
SHRINKAGE OF VITREOUS BODY CAUSED BY HYDROXYL RADICAL
Park, Myoung-Joo,Shimada, Takashi,Matuo, Yoichirou,Akiyama, Yoko,Izumi, Yoshinobu,Nishijima, Shigehiro The Korean Association for Radiation Protection 2008 방사선방어학회지 Vol.33 No.4
In this study, we examined the effect of hydroxyl radical generated by $\gamma$-ray and UV irradiation on shrinkage of vitreous body. Change in gel ratio of vitreous body and change in the properties of its components (collagen, sodium hyaluronate) were analyzed. By comparing these results, the amount of hydroxyl radical, which induces the considerable shrinkage of vitreous body, was evaluated from theoretical calculation based on experimental condition and some reported kinetic parameters. It was concluded that the integrated amount of hydroxyl radical required to liquefy half of the vitreous body (Vitreous body gel ratio = 50%) was estimated as $140\;{\mu}molg^{-1}$ from $\gamma$-ray irradiation experiment. Also, from UV irradiation experiment result, it was confirmed that the effect of hydroxyl radical is larger than that of other reactive species. The causes of shrinkage of vitreous body are supposed as follows, 1) decrease in viscosity by cleavage of glycoside bond in sodium hyaluronate, 2) leaching of collagen from vitreous body and 3) leaching of crosslinked products and scission products of collagen.
최진룡,송문태,조영손,송미광홍 한국국제농업개발학회 2000 韓國國際農業開發學會誌 Vol.12 No.1
Allelopathy has a potential in integrated weed management as a weed control strategy. Crop plants generally have the capability to exude allelochemicals into their surroundings, which can suppress the growth of weeds in their vicinity. In this paper extentive discussions were made on the agents of allelopathic activity and major research activities of allelopathic effects of rice in Japan, A series of experiments on selection for superior genotypes with allelopathic potential have been carried out with several rice cultivars or germplasms. Approaches to crop production that successfully reduce weed seed production can make farmers benefit by reducing management inputs and costs. Japanese allelopathy research team established a new testing method for the allelopathy potential in rice with the combination of biological test and field test. Among them, monochoria test was found to be most valuable for rice allelopathy test. Some old native rice cultivars of Pakistan, Philippines, and India were found to show high allelopathic potential than new cultivars of America and Japan. Upto date, although progress has been made in understanding the genetics of allelopathic activity of crop and successful genetic manipulation, further researches are required for a full degree of understanding of the genetic control of allelopathic activity in rice. Once the allelopathic genes are identified, a breeding program could be initiated to transfer the genes into modern cultivars and enhance their allelopathic activity in order to maximize weed suppression effects. Allelopathic research in rice should be cooperated with the research team of crop ecologists, soil scientists, agronomists, biochemists. plant physiologist, and farmers. This interest can be extended to effectiveness of cover crops, which is able to evaluate the allelopathy potential in the paddy field.