Chromosome aberrations and cell inactivation induced in mammalian cells by ultrasoft X-rays: correlation with the core ionizations in DNA.
OBJECTIVE
To study the frequency of chromosome aberrations induced by soft X-rays. To see if the core ionization of DNA atoms is involved in this end-point as much as it appears to be in cell killing.


METHODS
V79 hamster cells were irradiated by synchrotron radiation photons iso-attenuated in the cell (250, 350, 810eV). The morphological chromosome aberrations detected in the first post-irradiation cell division (dicentrics and centric rings) were studied by Giemsa staining.


RESULTS
The chromosome aberrations at 350eV were, respectively, 2.6 +/- 0.8 and 2.1 +/- 0.8 times more numerous than at 250 and 810eV for the same average dose absorbed by the nucleus. These relative effectivenesses are comparable with the ones already measured for cell killing. Moreover, they roughly vary such as the relative numbers of core ionizations (including in the phosphorus L-shell) produced in DNA and its bound water (water being involved only at 810eV through the oxygen atoms). In particular, they reproduce the characteristic twofold enhancement at 350eV, above the carbon K threshold.


CONCLUSIONS
Correlations suggest that the core ionization process is likely a common and essential mechanism initiating both chromosome aberration and cell killing end-points at these photon energies.
Gobert
F N
FN
Groupe de Physique des Solides, Université Paris 6 et Paris 7, T23, 2 place Jussieu, F-75 251 Paris Cedcx 05, France.
Lamoureux
M
M
Hervé du Penhoat
M A
MA
Ricoul
M
M
Boissière
A
A
Touati
A
A
Abel
F
F
Politis
M F
MF
Fayard
B
B
Guigner
J M
JM
Martins
L
L
Testard
I
I
Sabatier
L
L
Chetioui
A
A
D000818:Animals; D002244:Carbon / Q000737:chemistry; D002455:Cell Division; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002869:Chromosome Aberrations; D006224:Cricetinae; D004247:DNA / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D007477:Ions; D010100:Oxygen / Q000378:metabolism; D017785:Photons; D011839:Radiation, Ionizing; D011874:Radiometry; D014965:X-Rays
D007477:Ions; D002244:Carbon; D004247:DNA; D010100:Oxygen