The objective of this project is to describe the molecular mechanisms that regulate the temporal program of gene transcription during the differentiation of bacteria into dormant spores. DNA segments from the spore-forming bacterium Bacillus subtilis that contain genes whose transcription is activated at specific stages of sporulation will be cloned. These cloned DNAs will then serve as templates for examining transcription of developmentally-controlled genes in vitro by modified forms of RNA polymerase purified from sporulating bacteria.