Cytochrome Oxidase Activity in Blastocladiella emersonii

Studies of cytochrome oxidase in isolated mitochondria of Blastocladiella emersonii Cant. and Hyatt show that the enzyme was present in zoospores and throughout the development of ordinary colorless sporangia and of resistant sporangia. The enzyme activity was present in KCl, NaCl, NH4Cl, and $\text{KHCO}_{3}$ induced resistant sporangia, and was shown to be as active or more active than the enzyme found in ordinary colorless sporangia and zoospores. Interfering substances causing difficulties in the measurement of cytochrome oxidase activity were found in whole cell homogenates of $\text{KHCO}_{3}$ grown resistant sporangia, but not in KCl, NaCl, or NH4Cl grown thalli. These substances could be removed by dialysis or by sedimentation of the mitochondria.