日本語フィールド
著者：Ken-ichi Kudo, Hironori Ito, Satoshi Ihara and Hiroaki Terato
1題名：Oxidative DNA damage caused by pulsed discharge with cavitation on the bactericidal function発表情報：Journal of Physics D: Applied. Physics. 48 (2015) 365401 (12pp) 巻: Vol. 48 ページ: 365401 (12pp)キーワード：pulsed discharge, cavitation, reactive oxygen species, oxidative DNA damage, mass spectrometry, γ-rays概要：抄録：Plasma-based techniques are expected to have practical use for wastewater purification with
a potential for killing contaminated microorganisms and degrading recalcitrant materials.
In the present study, we analysed oxidative DNA damage in bacterial cells treated by the
plasma to unveil its mechanisms in the bactericidal process. Escherichia coli cell suspension
was exposed to the plasma induced by applying an alternating-current voltage of about
1 kV with bubbling formed by water-cavitation, termed pulsed discharge with cavitation.
Chromosomal DNA damage, such as double strand break (DSB) and oxidative base lesions,
increased proportionally with the applied energy, as determined by electrophoretic and mass
spectrometric analyses. Among the base lesions identified, the yields of 8-hydroxyguanine
(8-OH-G) and 5-hydroxycytosine (5-OH-C) in chromosomal DNA increased by up to 4- and
15-fold, respectively, compared to untreated samples. The progeny DNA sequences, derived
from plasmid DNA exposed to the plasma, indicated that the production rate of 5-OH-C
exceeded that of 8-OH-G, as G:C to A:T transitions accounted for 65% of all base changes,
but only a few G:C to T:A transversions were observed. The cell viabilities of E. coli cells
decreased in direct proportion to increases in the applied energy. Therefore, the plasmainduced
bactericidal mechanism appears to relate to oxidative damage caused to bacterial
DNA. These results were confirmed by observing the generation of hydroxyl radicals and
hydrogen peroxide molecules following the plasma exposure. We also compared our results
with the plasma to those obtained with 137Cs γ-rays, as a well-known ROS generator to
confirm the DNA-damaging mechanism involved.英語フィールド
Author：Ken-ichi Kudo, Hironori Ito, Satoshi Ihara and Hiroaki Terato
1Title：Oxidative DNA damage caused by pulsed discharge with cavitation on the bactericidal functionAnnouncement information:Journal of Physics D: Applied. Physics. 48 (2015) 365401 (12pp) Vol: Vol. 48 Page: 365401 (12pp)Keyword：pulsed discharge, cavitation, reactive oxygen species, oxidative DNA damage, mass spectrometry, γ-raysAn abstract：Plasma-based techniques are expected to have practical use for wastewater purification with
a potential for killing contaminated microorganisms and degrading recalcitrant materials.
In the present study, we analysed oxidative DNA damage in bacterial cells treated by the
plasma to unveil its mechanisms in the bactericidal process. Escherichia coli cell suspension
was exposed to the plasma induced by applying an alternating-current voltage of about
1 kV with bubbling formed by water-cavitation, termed pulsed discharge with cavitation.
Chromosomal DNA damage, such as double strand break (DSB) and oxidative base lesions,
increased proportionally with the applied energy, as determined by electrophoretic and mass
spectrometric analyses. Among the base lesions identified, the yields of 8-hydroxyguanine
(8-OH-G) and 5-hydroxycytosine (5-OH-C) in chromosomal DNA increased by up to 4- and
15-fold, respectively, compared to untreated samples. The progeny DNA sequences, derived
from plasmid DNA exposed to the plasma, indicated that the production rate of 5-OH-C
exceeded that of 8-OH-G, as G:C to A:T transitions accounted for 65% of all base changes,
but only a few G:C to T:A transversions were observed. The cell viabilities of E. coli cells
decreased in direct proportion to increases in the applied energy. Therefore, the plasmainduced
bactericidal mechanism appears to relate to oxidative damage caused to bacterial
DNA. These results were confirmed by observing the generation of hydroxyl radicals and
hydrogen peroxide molecules following the plasma exposure. We also compared our results
with the plasma to those obtained with 137Cs γ-rays, as a well-known ROS generator to
confirm the DNA-damaging mechanism involved.