Abstract: | At low and high concentrations, respectively, KCN stimulatedand inhibited the CO2 output of radish root slices. Analysisof tissue slices showed that CO2 production is nearly accountedfor by the loss in carbohydrates. After 48 hr, the content ofprotein-N was slightly changed in all the cyanide-treated tissues;whereas, that of soluble-N decreased markedly at high cyanideconcentrations and hardly changed at low concentrations. Leakageof soluble-N occurred at high concentrations of cyanide. The nitrogen compounds taken up were incorporated into the nitrogenpool of radish slices. KCN retarded uptake of nitrogen compounds,inhibited their utilization and led to excessive leakage ofsoluble-N from the tissues into the media. Increased CO2 outputof slices in nitrogen media was largely accounted for by theloss in carbohydrates from the tissues. High concentrations of cyanide are thought to inhibit CO2 outputthrough inhibition of the oxidase system and accompanying phosphorylations.The present results with low concentrations further substantiatethe uncoupling theory as a main factor involved in respiration.
1Permanent address: Department of Botany, Faculty of Science,University of A'in Shams, Abbassia, Cairo, Egypt, U.A.R. (Received October 3, 1969; ) |