Cover photograph (Copyright © 2015, American Society for Microbiology. All Rights Reserved.): Head-on replication-transcription conflict. Collisions between replication and transcription stall the fork, disrupt both machineries, and potentially break the DNA. Cells must reactivate replication forks stalled by conflicts with transcription, as well as repair any DNA breaks that may occur in order to complete chromosome duplication and produce viable progeny. (See related article on page 2374.)