title: Irradiation of micro-organisms with mono-energetic X-rays; biological consequences of the Auger effect.
abstract: The radiation resonance effect reported previously for isolated biomolecules has now for the first time been observed in a cellular system. Dried bacteria, Micrococcus denitrificans, in which TdR in DNA was partially substituted by BUdR, were subjected to mono-energetic X-rays of energies below or above the K-edge for Br. Subsequently, the colony-forming ability was assayed. For photon energy slightly above the K-edge, the lethality/rad was greater than that below the K-edge. This is interpreted in terms of the Auger effect initiated selectively by photo-absorption in constituent Br atoms. The differential absorption of low-energy photons in constituent atoms of DNA is also discussed.
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000528:radiation effects; D004247:DNA / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004583:Electrons; D004735:Energy Transfer; D010231:Paracoccus denitrificans / Q000528:radiation effects*; D014965:X-Rays
chemical_list: D004247:DNA