Inhibition of meiosis in Saccharomyces cerevisiae by ammonium ions: Interference of ammonia with protein metabolism.

Meiosis and sporogenesis in yeast are completely blocked by ammonia added in low concentration (10 mM) to the sporulation medium. Premeiotic DNA synthesis is not initiated in the presence of ammonium ions. The inhibitor interferes with protein turnover by reducing both synthesis and breakdown. The in vitro activities of proteinases A and B in sporulation medium supplemented with ammonia are much lower than in the control. This may partially explain the effect of ammonium ions on protein metabolism in vivo.