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@ARTICLE{Unverricht:1040831,
author = {Unverricht, Marcus and von Ameln, Marcel and Kriehuber,
Ralf},
title = {{I}nduction of {C}hromosomal {A}berrations after {E}xposure
to the {A}uger {E}lectron {E}mitter {I}odine-125, the
β–-emitter {T}ritium and {C}esium-137 γ rays},
journal = {Radiation research},
volume = {201},
number = {5},
issn = {0033-7587},
address = {Great Falls, Va.},
publisher = {Radiation Research Society},
reportid = {FZJ-2025-01999},
pages = {479-486},
year = {2024},
abstract = {The biological effectiveness of ionizing radiation
dependsnot only on dose or dose rate but also on the LET
(linearenergy transfer) of the radiation. For example, a
particle withan LET of 100 keV/mm causes a minimum of 15
ionizationswhen traversing a single DNA double-helix
molecule and,therefore, may induce complex DNA lesions,
(1–5) which arerepaired less efficiently or completely
(6–8) compared to alower LET radiation, resulting in a
higher relative biologicaleffectiveness. When Auger electron
emitters (AEE) such asiodine-125 (125I) decay, low-energy
Auger electrons with ashort range of 1–10 nm (9) deposit a
high amount of energy inan extremely small volume, which is
why Auger electronemission is considered as high-LET
radiation (10–12). Iodine-125 emits an average of 13
low-energy Auger electrons perdecay (13) and is known to
induce complex DNA lesionswhen incorporated into DNA (14,
15), resulting in high-LETtype effects (e.g., cell survival
curves with no shoulder region)(16–18).To investigate
whether the complexity of DNA lesionsaffects the formation
of chromosomal aberrations (CA),three different radiation
qualities were studied, namely 137Csc rays (662 keV),125I
incorporated into cellular DNA as 125I-iododeoxyuridine
(125I-UdR) and 3H, incorporated into cellu-lar DNA as
tritiated thymidine. DNA-incorporated tritiatedthymidine is
known to have a slightly increased RBE com-pared to low-LET
radiation (19) because of the low energyof the b particles
emitted during decay (mean energy of 5.7keV). Energy spectra
of 125I Auger electrons show maximumenergies up to 35.4 keV,
with most Auger electrons havingvery low energies of
20–500 eV (9, 20). To classify the bio-logical
effectiveness of the two very different radionuclides,we
used c radiation as a reference radiation for comparison.In
addition to the impact of varying complexity of DNAlesions
induced by the radiation qualities used here on CA,this
study also investigates whether the cell cycle phase in1
Marcus Unverricht-Yeboah, Forschungszentrum J€ulich,
Departmentof Safety and Radiation Protection,
Wilhelm-Johnen-Strasse J€ulich,Germany; email:
m.unverricht@fz-juelich.de.479RADIATION RESEARCH 201,
479–486 (2024)0033-7587/24 $15.00Ó2024 by Radiation
Research Society.All rights of reproduction in any form
reserved.DOI: 10.1667/RADE-23-00158.1Downloaded From:
https://bioone.org/journals/Radiation-Research on 23 Jan
2026Terms of Use: https://bioone.org/terms-of-usewhich the
exposure occurs has an impact on the inductionof CA. Cell
cycle phases differ with respect to 3D chromatinstructure,
which may have an impact on the extent of thecomplexity of
DNA lesions and/or their repair. Whereaschromatin in S phase
and in the transcriptionally active G1phase is relatively
relaxed and open, chromatin in G2 phaseand mitosis is more
condensed and/or already denselypacked; this is likely the
main reason why G2/M cells are themost radiosensitive cells
(21). Whether DSBs are convertedinto chromosomal aberrations
depends on the fidelity of dif-ferent principal DNA repair
pathways: non-homologous endjoining (NHEJ), which is
available throughout the cell cycle,and homologous
recombination (HR), which is only activein S and G2 phase
(22–26).To compare all radiation qualities and to avoid
microdo-simetric approaches with rather high dose
uncertainties,especially for the low-energy electrons
(particularly in thecase of Auger electron emitter (AEE)
125I), the induction ofchromosomal aberrations was
normalized to induction ofc-H2AX foci, which are widely
regarded and accepted asan indicator of DSB (27–30).},
cin = {IBI-1 / S-US},
ddc = {530},
cid = {I:(DE-Juel1)IBI-1-20200312 / I:(DE-Juel1)S-US-20090406},
pnm = {5241 - Molecular Information Processing in Cellular Systems
(POF4-524)},
pid = {G:(DE-HGF)POF4-5241},
typ = {PUB:(DE-HGF)16},
pubmed = {38407403},
UT = {WOS:001226507700012},
doi = {10.1667/RADE-23-00158.1},
url = {https://juser.fz-juelich.de/record/1040831},
}