When apical bud sections ofPhaseolus vulgariswere vacuum-infiltrated with malformin, their rate of respiration increased significantly without a lag and without altering the respiratory quotient. When tissues were soaked in solutions, the effect of malformin was concentration dependent. At high malformin concentration (200μM), a marked inhibition of respiration for 8 to 10 hr was followed by a rapid increase of oxygen uptake which reached a level nearly 3-fold greater than that of controls. At lower concentration (20μM) malformin had no effect on respiration for 8 to 10 hr, but then stimulated respiration markedly. Ca2+completely blocked the early inhibition of respiration by malformin (200μM), but had little or no effect on the subsequent stimulation of respiration. Oxygen deficiency may be a contributing factor to the enhancement of ethane production by malform
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