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Dive into the research topics where Kotaro Hieda is active.

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Featured researches published by Kotaro Hieda.


Photochemistry and Photobiology | 1991

WAVELENGTH DEPENDENT FORMATION OF THYMINE DIMERS AND (6-4)PHOTOPRODUCTS IN DNA BY MONOCHROMATIC ULTRAVIOLET LIGHT RANGING FROM 150 TO 365 nm

Tsukasa Matsunaga; Kotaro Hieda; Osamu Nikaido

Abstract—We investigated the wavelength dependence of cyclobutane thymine dimer and (6‐4)photo‐product induction by monochromatic UV in the region extending from 150 to 365 nm, using an enzyme‐linked immunosorbent assay with two monoclonal antibodies. Calf thymus DNA solution was irradiated with254–365 nm monochromatic UV from a spectrograph, or with220–300 nm monochromatic UV from synchrotron radiation. Thymine dimers and (6‐4)photoproducts were fluence‐dependently induced by every UV wavelength tested so far. We also examined the induction of both types of DNA damage by UV below 220 nm extending to 150 nm under dry condition. We detected the efficient formation of both types of damage in the shorter UV region, as well as at 260 nm, which had been believed to be the most efficient wavelength for the formation of UV lesions. The action spectra for the induction of thymine dimers and (6‐4)photoproducts were similar from 180 to 300 nm, whereas the action spectrum values for thymine dimer induction were about 9‐ and 1.4‐fold or more higher than the values for (6‐4)photoproduct induction below 160 nm and above 313 nm, respectively.


Photochemistry and Photobiology | 1991

INACTIVATION ACTION SPECTRA OF BACILLUS SUBTILIS SPORES IN EXTENDED ULTRAVIOLET WAVELENGTHS (50–300nm) OBTAINED WITH SYNCHROTRON RADIATION

Nobuo Munakata; Mikio Saito; Kotaro Hieda

Five types of Bacillus subtilis spores (UVR, UVS, UVP, RCE, and RCF) differing in repair and/or recombinational capabilities were exposed to monochromatic radiations at 13 wavelengths from 50 to 300 nm in vacuum. An improved biological irradiation system connected to a synchrotron radiation source was used to produce monochromatic UV radiation in this extended wavelength range with sufficient fluence to inactivate bacterial spores. From the survival curves obtained, the action spectra for the inactivation of the spores were depicted. Recombination‐deficient RCE (recE) and RCF (recF) spores were more sensitive than the wild‐type UVR spores in the entire range of wavelengths. This was considered to mean that DNA was the major target for the inactivation of the spores. Vacuum‐UV radiations of125–175 nm were effective in killing the spores, and distinct peaks of the sensitivity were seen with all types of the spores. Insensitivities at 190 and 100 nm were common to all five types of spores, indicating that these wavelengths were particularly impenetrant and absorbed by the outer layer materials. The vacuum‐UV peaks centering at 150 nm were prominent in the spores defective in recombinational repair, while the far‐UV peaks at around 235 and 270 nm were prominent in the UVS (uvrA ssp) and UVP (uvrA ssp polA) spores deficient in removal mechanisms of spore photoproducts. Thus, the profiles of the action spectra were explained by three factors; the penetration depth of each radiation in a spore, the efficiency of producing DNA damage that could cause inactivation, and the repair capacity of each type of spore.


Current Genetics | 1988

A colony procedure for transformation of Saccharomyces cerevisiae.

David Keszenman-Pereyra; Kotaro Hieda

SummaryA rapid and simple yeast transformation procedure has been developed using colonies on agar plates. Saccharomyces cerevisiae SHY3 cells were picked up from colonies on YPD plates grown freshly or stored at 4 °C and incubated with M13RK9-T DNA at 30 °C for 1–2 h in a solution of Li+, Ca2+, Mg2+, triacetin and polyethylene glycol. About 3,500 transformants were obtained per µg of double stranded M13RK9-T DNA. Unlike the existing spheroplast techniques, single stranded M13RK9-T DNA transformed intact cells below one-hundredth frequency of the duplex form.


International Journal of Radiation Biology | 1996

Single- and double-strand breaks in pBR322 plasmid DNA by monochromatic X-rays on and off the K-absorption peak of phosphorus

Kotaro Hieda; T. Hirono; A. Azami; M. Suzuki; Y. Furusawa; Hiroshi Maezawa; N. Usami; A. Yokoya; Katsumi Kobayashi

Using a synchrotron irradiation system pBR322 plasmid DNA was irradiated under vacuum by monochromatic X-rays having five specific photon energies (2.147, 2.153, 2.159, 2.168 and 2.199 keV) both on and off the K-absorption peak (2.153 keV) of phosphorus. The single- and double-strand breaks (ssb and dsb) were measured as conversions of the closed circular form of DNA (form I) to open circular (form II) and linear (form III) forms respectively. Exposures to induce one strand break per molecule were lowest at the peak (2.153 keV), and highest at 2.147 keV; the ratios were 2.7 for ssb and 3.0 for dsb. The exposures for dsb were 21-26 times higher than those for ssb. When the exposures were converted to absorbed doses in grays the absorbed doses per ssb were almost independent of photon energy. This result indicates that a certain absorbed dose was necessary to induce a ssb, regardless of whether photons were absorbed by the K-shell of phosphorus or by other shells, or by other atoms. However, the absorbed dose per dsb at 2.147 keV was 1.17 times higher than that averaged over four X-ray energies above 2-153 keV, indicating that the K-shell absorption, and the subsequent Auger event, efficiently induce dsb. The results are also discussed concerning the number of photo-absorptions of the constituent atoms per DNA strand break.


Photochemistry and Photobiology | 1996

Experimental Correspondence between Spore Dosimetry and Spectral Photometry of Solar Ultraviolet Radiation

Nobuo Munakata; Fumiko Morohoshi; Kotaro Hieda; Keiji Suzuki; Yoshiya Furusawa; Hidehiro Shimura; Tomoyuki Ito

Abstract— The biologically effective dose of solar UV radiation was estimated from the inactivation of UV‐sensitive Bacillus subtilis spores. Two types of independent measurements were carried out concurrently at the Aerological Observatory in Tsukuba: one was the direct measurement of colony‐forming survival that provided the inactivation dose per minute (ID/min) and the other was the measurement of the spectral irradiance by a Brewer spectrophotometer. To obtain the effective spectrum, the irradiance for each 1 nm wavelength interval from 290 to 400 nm was multiplied with the efficiency for inactivation derived from the inactivation action spectrum of identically prepared spore samples. Integration of the effective spectrum provided the estimate for ID/min. The observed values of ID/min were closely concordant with the calculated values for the data obtained in four afternoons in 1993. The average ratio (±SD) between them was 1.24 (±0.16) for 14 data points showing high inactivation rates (<0.05 ID/min). Considering difficulties in the absolute dosimetry of UV radiation, the concordance was satisfactory and improved credibility of the two types of monitoring systems of biologically effective dose of solar UV radiation.


Radiation Research | 1984

Synchrotron system for monochromatic uv irradiation (>140 nm) of biological material

Takashi Ito; Tsuneo Kada; Shigefumi Okada; Kotaro Hieda; Katsumi Kobayashi; Hiroshi Maezawa; Atsushi Ito

An irradiation system of monochromatic uv radiation down to the wavelength of 140 nm was constructed for biological irradiation experiments in the vacuum-uv range using synchrotron radiation (SR) from the electron storage ring. The system consists of premirror chamber, vacuum-uv monochromator, irradiation chamber, and vacuum systems. Along with the detailed description of all components of the system, the installation at the storage ring and the performance characteristics are presented.


Radiation Research | 1983

Wavelength Dependence of Inactivation and Membrane Damage to Saccharomyces cerevisiae Cells by Monochromatic Synchrotron Vacuum-uv Radiation (145-190 nm)

Takashi Ito; Atsushi Ito; Kotaro Hieda; Katsumi Kobayashi

Using an electron storage ring as a source of radiation, the wavelength dependence of inactivation and membrane damage in yeast cells (Saccharomyces cerevisiae) was investigated in the range from 145 to 254 nm, with special reference to the effects of vacuum-uv radiation. The cells were irradiated on a Millipore filter in a moist chamber filled with water vapor (deoxygenated) at saturation pressure. Fluence-survival curves taken at 5-nm intervals were generally sigmoidal. Action spectra of the two types of effects were nearly identical in shape. The maximum occurred in both spectra at 160 nm, decreasing sharply toward 180 nm. The spectra remarkably resembled the calculated absorption spectrum of (liquid) water in the range from 145 to 170 nm; the spectra had no similarity at all to the absorption spectra of DNA, proteins, or lipids. These data support the theory that inactivation of wet cells by vacuum-uv radiation may be attributable to damage in the cell membrane initiated by the absorption of water molecules. Above 210 nm the spectrum for inactivation paralleled the absorption of DNA. Genetic changes (induction of gene conversion) were also observed above 210 nm. Photoreversion for the induced convertants was detectable only above 220 nm. These characteristics are consistent with the expectation that above 210 nm the site of major lethal damage shifts to DNA.


Photochemistry and Photobiology | 2000

Comparisons of Spore Dosimetry and Spectral Photometry of Solar-UV Radiation at Four Sites in Japan and Europe¶

Nobuo Munakata; Stelios Kazadzis; A. F. Bais; Kotaro Hieda; Györgyi Rontó; Petra Rettberg; Gerda Horneck

Abstract In order to develop monitoring and assessment systems of biologically effective doses of solar-UV radiation, concurrent measurements of spectral photometry and spore dosimetry were conducted in summer months at four sites in Japan and Europe. Effectiveness spectra were derived by multiplying spectral irradiance in 0.5 nm steps between 290 and 400 nm with the inactivation efficiency of the spores determined using monochromatic radiation of fine wavelength resolution. Shapes of the effectiveness spectra were very similar at the four sites exhibiting major peaks at 303.5, 305.0, 307.5 and 311.0 nm. The dose rates for spore inactivation from direct survival measurements and from calculations by the integration of the effectiveness spectra were compared for 174 data points. The ratios (observed/calculated) of the two values were concordant with a mean of 1.26 (±0.24 standard deviation [SD]). The possible causes for the variations and slightly larger observed values are discussed.


Journal of Radiation Research | 2013

SPICE-NIRS microbeam: a focused vertical system for proton irradiation of a single cell for radiobiological research.

Teruaki Konishi; Masakazu Oikawa; Noriyoshi Suya; Takahiro Ishikawa; Takeshi Maeda; Alisa Kobayashi; Naoko Shiomi; Kumiko Kodama; Tsuyoshi Hamano; Shino Homma-Takeda; Mayu Isono; Kotaro Hieda; Yukio Uchihori; Yoshiyuki Shirakawa

The Single Particle Irradiation system to Cell (SPICE) facility at the National Institute of Radiological Sciences (NIRS) is a focused vertical microbeam system designed to irradiate the nuclei of adhesive mammalian cells with a defined number of 3.4 MeV protons. The approximately 2-μm diameter proton beam is focused with a magnetic quadrupole triplet lens and traverses the cells contained in dishes from bottom to top. All procedures for irradiation, such as cell image capturing, cell recognition and position calculation, are automated. The most distinctive characteristic of the system is its stability and high throughput; i.e. 3000 cells in a 5 mm × 5 mm area in a single dish can be routinely irradiated by the 2-μm beam within 15 min (the maximum irradiation speed is 400 cells/min). The number of protons can be set as low as one, at a precision measured by CR-39 detectors to be 99.0%. A variety of targeting modes such as fractional population targeting mode, multi-position targeting mode for nucleus irradiation and cytoplasm targeting mode are available. As an example of multi-position targeting irradiation of mammalian cells, five fluorescent spots in a cell nucleus were demonstrated using the γ-H2AX immune-staining technique. The SPICE performance modes described in this paper are in routine use. SPICE is a joint-use research facility of NIRS and its beam times are distributed for collaborative research.


Photochemistry and Photobiology | 1992

Wavelength dependence (150-290 nm) of the formation of the cyclobutane dimer and the (6-4) photoproduct of thymine

Hiroyuki Yamada; Kotaro Hieda

Abstract— The action cross sections for the formation of the cyclobutane dimer and the (6–4) photoproduct of thymine as well as the absorption cross sections of thymine were determined in the wavelength region between 150 and 290 nm. Thymine films sublimed on glass plates were irradiated by monochromatic photons in a vacuum; the induced photoproducts were quantitatively analyzed by high‐performance liquid chromatography (HPLC). Under our conditions, two major peaks appeared on the HPLC chromatograms of irradiated samples. The two peaks were identified as being the cis‐syn cyclobutane dimer and the (6–4) photoproduct, based on their HPLC retention times, absorption spectra in the effluent, and photochemical reactivity. The fractions of the two photoproducts increased linearly with the fluence at low fluences over the entire wavelength range. Their action cross sections were determined by the slopes of the linear fluence response curve at 10 nm intervals between 150 and 290 nm. The two action spectra showed a similar wavelength dependence and had a maximum at 270 nm as well as two minor peaks at 180 and 220 nm, at which wavelengths the peaks of the absorption spectrum of thymine sublimed on a CaF2 crystal plate appeared. The quantum yields had relatively constant values of around 0.008 for the dimer and 0.013 for the (6–4) photoproduct above 200 nm, decreasing to 0.003 and 0.006, respectively, at 150 nm as the wavelength became shorter.

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Teruaki Konishi

National Institute of Radiological Sciences

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Kaoru Takakura

International Christian University

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Nakahiro Yasuda

National Institute of Radiological Sciences

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Takashi Ito

Kansas State University

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