In this study we evaluated the effect of linear energy transfer (LET) and chromatin structure on the
induction of chromosomal inversion. High LET radiation causes more complex DNA damage than low LET radiation;
this “dirty” damage is more difficult to repair and may result in an increase in inversion formation. CHO10B2 cells
synchronized in either G1 or M phase were exposed 0, 1, or 2 Gy of 5 mm Al and Cu filters at 200 kVp and 20 mA
X-rays or 500 MeV/nucleon of initial energy and 200 keV/μ m Fe ion radiation. In order to increase the sensitivity of
prior techniques used to study inversions, we modified the more traditional Giemsa plus fluorescence technique so
that cells were only allowed to incorporate BrdU for a single cycle verses 2 cycles. The BrdU incorporated DNA
strand was labeled using a BrdU antibody and an Alexa Fluor 488 probe. This modified technique allowed us to
observe inversions smaller than 0.6 megabases (Mb).

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• Role of LET and chromatin structure on chromosomal inversion in CHO10B2 cells