RESPIRATORY BLOCK IN THE DORMANT SPORES OF NEUROSPORA TETRASPERMA

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Abstract
The respiratory rates at various partial pressures of O2 and CO2 indicate that permeability of the spores to gases is not limiting. Studies on the cyanide- and CO- sensitivity of dormant and activated spores indicate that phaeohemin (indophenol oxidase) activity is not limiting. The dormant spores produce no CO2 anaerobically, while the activated spores have a Q[image] of 5 to 8, though the rate falls to zero after 3-4 hrs. It is suggested that no active carboxylase is present in dormant spores, but that carboxylase is reversibly activated on heat treatment. The activation-deactivation of carboxylase parallels the effect of activation and deactivation on respiration and germination. 2 qualitatively different respiratory systems are apparently present: the dormant system, which functions in the absence of carboxylase, and a 2d system, active in heat treated spores, which passes over carboxylase. The respiratory block is then the inactivity of carboxylase.

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