Practice question

Prespore program depends on sustained exposure to millimolar extracellular cAMP that maintains high intracellular cAMP and active protein kinase A. PKA directly suppresses prestalk-specific genes while activating prespore coat genes SP70, SP96, and cotB. Laboratory induction uses bromo-cAMP to stimulate prespore markers even in low density cultures lacking cell contacts. Low cAMP with DIF-1反而 drives prestalk differentiation, and absence of cAMP blocks both lineages retaining vegetative state. High ammonia further reinforces prespore fate by inhibiting tip organizer. Therefore high persistent cAMP serves as posterior positional signal consolidating spore competence and maintaining slug integrity.