The effect of 2,4-dinitrophenol and cupferron on the production of chromatid aberrations by X-rays in Vicia faba

Abstract

The effect of 2,4-dinitrophenol (DNP) on oxygen consumption and the production of chromatid aberrations by X-rays was studied and compared with that of cupferron. The experimental material consisted of lateral root tips of the broad bean, Vicia faba. The X-ray effect at intermediate concentrations of oxygen (7 per cent) was decreased by DNP in concentrations which stimulated respiration (10–20 μM) and increased by DNP concentrations which inhibited respiration (200 μM). The results are in agreement with the idea that there is a respiration-dependent oxygen gradient in the root. At low oxygen tension (2 per cent) cupferron, but not DNP (100 μM), markedly increased the frequencies of aberrations both at “high” (120 r/min) and at “low” (6.4 r/min) dose rates. Apparently, the enhancement is due to the inhibitory effect of cupferron on respiration, which would result in an elimination of the oxygen gradient in the root. In an oxygen atmosphere, both cupferron and DNP (100 μM) increased the frequencies of X-ray-induced interchanges at low dose rates. At high dose rates this effect disappeared. It seems likely that DNP and cupferron bring about this increase by inhibiting the production of the energy-rich phosphate needed for the repair of chromosome damage.