[1] Univ Leicester, Dept Genet, Leicester LE1 7RH, Leics, England
[2] CEA, Lab Genet Radiosensibil, Dept Radiobiol & Radiopathol, Direct Sci Vivant, F-92265 Fontenay Aux Roses, France
[3] Leiden Univ, Ctr Med, Sylvius Lab, Dept Toxicogenet, NL-2333 Leiden, Netherlands