RAD51 and infection: Skalka etal. [31] stated that replication via the “early mode occurs only once or twice, after which rolling circle (late) replication predominates.” They suggested that a direct, internal control gene for the turn-off of early replication either “does not exist”, or “must not be expressed in the absence of replication” because early replication products accumulate (after infection or induction) when concatemer formation is destabilized in λ gam mutants, or under fec− conditions (involving both λ red and host recA mutations).