0.3 keV carbon K ultrasoft X-rays are four times more effective than gamma-rays when inducing oncogenic cell transformation at low doses.

Oncogenic transformation and inactivation were investigated in C3H10T1/2 mouse embryo fibroblasts exposed to proton-induced 0.28 keV carbon K (CK)-characteristic X-rays and 60Co gamma-rays as reference radiation at high dose-rate (2-3 and 0.7 Gy/min respectively).

Half-life values for DNA double-strand break rejoining in yeast can vary by more than an order of magnitude depending on the irradiation conditions.

Yeast cells in stationary phase were exposed under oxic or anoxic conditions to sparsely (30 MeV electrons) or densely (3.5 MeV alpha-particles) ionizing radiation. For all four experimental set-ups postirradiation treatment of cells was the same, i.

Evidence against the "oxygen-in-the-track" hypothesis as an explanation for the radiobiological low oxygen enhancement ratio at high linear energy transfer radiation.

Oxygen sensitizes cells toward the effect of ionizing radiation. This sensitization, quantified by the oxygen enhancement ratio (OER), decreases with increasing ionization density or linear energy transfer (LET) of the radiation applied. One explanation for the decreased OER at high LET offers the "oxygen-in-the-track" hypothesis.