Practice question

In Dictyostelium slug ammonia is metabolic waste acting as signaling molecule regulating cell fate proportion. High ammonia concentration, generated by protein catabolism, inhibits prestalk differentiation by antagonizing DIF-1 signaling and raising intracellular pH, favoring prespore gene expression including spore coat proteins and promoting slug migration rather than stalk formation. Low ammonia permits DIF-1 dependent prestalk maturation and culmination into stalk cells. In sorus ammonia drop triggers terminal differentiation. Thus elevated ammonia within slug microenvironment biases toward spore formation, extending migratory phase seeking favorable fruiting site while suppressing premature stalk specification essential for survival strategy.