DEVELOPMENT OF TREHALASE AND INVERTASE ACTIVITY IN NEUROSPORA

Abstract

Hill , E. P. (University of Michigan, Ann Arbor), and A. S. Sussman . Development of trehalase and invertase activity in Neurospora . J. Bacteriol. 88: 1556–1566. 1964.—The levels of trehalase and invertase found during the development of Neurospora have been studied. Invertase activity is highest in the mycelium after growth has been completed, whereas the most trehalase activity is found in ungerminated conidia. Both enzymes show the least activity in the ascospore. Although the specific activity of trehalase varies no more than 3-fold during the spore stages, there is a 60-fold change in the mycelium. Similar but less pronounced variations in the specific activity of invertase in the mycelium occur. The lowest ratios of invertase to trehalase activity in the soluble fraction are found in conidia and ascospores, except in dormant ascospores where the ratio approaches that of older mycelium. Similar results are obtained for the enzymes in the wall fraction, except for dormant and newly activated ascospores. Moreover, the walls of young mycelium appear to have relatively more trehalase than is found at all other times. The activities of both enzymes vary about 20-fold in the wall fraction, but invertase activity fluctuates more widely than that of trehalase. Invertase activity always exceeds that of trehalase, and the cytoplasmic fraction contains more activity than that of the wall. These results are shown to contradict the hypothesis that trehalase and invertase activities are coordinately controlled. Finally, the role of trehalase in the activation of ascospores is considered in the light of these results.