Influence of the sampling time on chromosomal aberrations at G2 phase in Syrian hamster embryonic cells irradiated with different types of radiation.
OBJECTIVE
To investigate the time-course of chromosomal aberrations following radiations of differing LET.


METHODS
Syrian hamster embryonic cells were irradiated with nitrogen ions (LET(infinity) = 530 keV/microm) and helium-ions (LET(infinity) = 36 and 77 keV/microm), also 137Cs gamma-rays as a reference radiation. The frequency of chromatid-type aberrations was determined after 0-6 h incubation in a 5% CO2 incubator at 37 degrees C.


RESULTS
The amount of chromosomal damage per cell for nitrogen ions detected immediately after irradiation was lower than induced by 137Cs gamma-rays. In contrast, helium ions were more effective than gamma rays in inducing chromatid type damage. The RBE values for the nitrogen-ion beams were 0.45 for gaps, 0.43 for deletions and 0.20 for exchanges. For helium-ion beams, the RBE values for the 36 keV/microm beams and the 77 keV/microm beams were 1.2 and 1.5 for gaps, 1.3 and 2.1 for deletions, and 1.5 and 1.9 for exchanges, respectively. The frequency of cells with chromosomal damage following exposure to gamma-rays and helium-ion beams showed a downward trend with increasing incubation period. In contrast, in the case of nitrogen-ion beams, there was an increase with the incubation period.


CONCLUSIONS
The results show that it is possible to underestimate chromosomal damage for different types of radiation by scoring aberrations at a single fixed sampling time.
Suzuki
M
M
International Space Radiation Laboratory, National Institute of Radiological Sciences, Chiba, Japan.
Nakano
K
K
Suzuki
K
K
Watanabe
M
M
D000818:Animals; D016923:Cell Death / Q000528:radiation effects; D002478:Cells, Cultured; D002869:Chromosome Aberrations; D006224:Cricetinae; D004307:Dose-Response Relationship, Radiation; D016195:G2 Phase / Q000528:radiation effects*; D005720:Gamma Rays / Q000009:adverse effects; D006371:Helium; D018499:Linear Energy Transfer; D008647:Mesocricetus; D009584:Nitrogen; D012062:Relative Biological Effectiveness; D013997:Time Factors
D006371:Helium; D009584:Nitrogen