@misc{oai:repo.qst.go.jp:00077418,
 author = {Obata, Yui and Hirasaki, Keishiro and Yokoya, Akinari and Akimitsu, Nobuyoshi and Obata, Yui and Hirasaki, Keishiro and Yokoya, Akinari},
 month = {Nov},
 note = {Whole cell irradiation inevitably causes various
damage in not only genomic DNA but also intracellular
organelles. In order to separately examine repairability
of DNA damage from damage responses of organelles,
EGFP-expressing plasmid DNA (in TE buffer) was
exposed to X-rays in vitro, and then transfected into "
NON-irradiated " human breast cancer cells (MCF7). The
dynamics of EGFP fluorescence of cells was observed
by a live cell imaging technique to analyze DNA repair
efficiency in the cells. The EGFP expression kinetics as
DNA repair efficiency was analyzed for the cells transfected
with the plasmids exposed to several X-ray doses.
The similar experiments were also performed using
plasmids treated with nicking or restriction enzyme to
obtain positive control data of SSB or DSB induction,
respectively. Based on those positive control values,
theoretically expected efficiencies were also calculated
assuming that strand breakage of plasmid DNA by irradiation
followed Poisson distribution. The numbers of
cells expressing EGFP in the experimental results were
considerably fewer than the theoretical values, indicating
that the irradiated plasmids were less repaired in the
cells. These results strongly suggest that X-irradiation
causes complex types of strand break termini rather
than those created by enzymatic treatments, presumably
so called non-DSB type clustered DNA damage.
These particular types of radiation induced damage
would compromise DNA repair efficiency, consequently
induce down-regulation of EGFP expression., 日本放射線影響学会第62回大会},
 title = {Live cell observation of EGFP expression of in vitro X-irradiated plasmid DNA in non-irradiated human cells},
 year = {2019}
}