Tunicamycin inhibition of epispore formation in Saccharomyces cerevisiae.

The ascopore wall of Saccharomyces cerevisiae was found to contain more protein, polymeric glucosamine, and beta-glucan than the vegetative cell wall, which was enriched in mannoprotein relative to ascospore walls. Tunicamycin inhibited sporulation, as judged by the absence of refractile ascospores visible by phase-contrast microscopy, but cells completed meiosis, as demonstrated by the presence of multinucleate asci. Such spores lacked the dense outer layer characteristic of normal spores. Thus, the tunicamycin effect was similar to that of glucosamine auxotrophy (W. L. Whelan and C. E. Ballou, J. Bacteriol. 124:1545-1557, 1975).