title: Electron Resonance Decay into a Biological Function: Decrease in Viability of E. coli Transformed by Plasmid DNA Irradiated with 0.5-18 eV Electrons.
abstract: Transient negative ions (TNIs) are ubiquitous in electron-molecule scattering at low electron impact energies (0-20 eV) and are particularly effective in damaging large biomolecules. Because ionizing radiation generates mostly 0-20 eV electrons, TNIs are expected to play important roles in cell mutagenesis and death during radiotherapeutic cancer treatment, although this hypothesis has never been directly verified. Here, we measure the efficiency of transforming E. coli bacteria by inserting into the cells, pGEM-3ZfL(-) plasmid DNA that confers resistance to the antibiotic ampicillin. Before transformation, plasmids are irradiated with electrons of specific energies between 0.5 and 18 eV. The loss of transformation efficiency plotted as a function of irradiation energy reveals TNIs at 5.5 and 9.5 eV, corresponding to similar states observed in the yields of DNA double strand breaks. We show that TNIs are detectable in the electron-energy dependence of a biological process and can decrease cell viability.
authors.affiliation: Groupe en Sciences des Radiations, Département de médecine nucléaire et Radiobiologie, Faculté de Médecine, Université de Sherbrooke , Sherbrooke, Quebec J1H 5N4, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Kouass Sahbani
authors.affiliation: Groupe en Sciences des Radiations, Département de médecine nucléaire et Radiobiologie, Faculté de Médecine, Université de Sherbrooke , Sherbrooke, Quebec J1H 5N4, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Cloutier
authors.affiliation: Groupe en Sciences des Radiations, Département de médecine nucléaire et Radiobiologie, Faculté de Médecine, Université de Sherbrooke , Sherbrooke, Quebec J1H 5N4, Canada.
authors.forename: A D
authors.initials: AD
authors.lastname: Bass
authors.affiliation: Groupe en Sciences des Radiations, Département de médecine nucléaire et Radiobiologie, Faculté de Médecine, Université de Sherbrooke , Sherbrooke, Quebec J1H 5N4, Canada.
authors.forename: D J
authors.initials: DJ
authors.lastname: Hunting
authors.affiliation: Groupe en Sciences des Radiations, Département de médecine nucléaire et Radiobiologie, Faculté de Médecine, Université de Sherbrooke , Sherbrooke, Quebec J1H 5N4, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Sanche
mesh_terms: D004247:DNA / Q000235:genetics / Q000528:radiation effects*; D004249:DNA Damage; D004583:Electrons; D004926:Escherichia coli / Q000235:genetics*; D010957:Plasmids; D014169:Transformation, Bacterial
chemical_list: D004247:DNA
keywords: DNA; cell transformation efficiency; low-energy electrons; radiation damage; transient anions