FIG 2.

Northern analysis of CRISPR array transcription. Total RNA of P. gingivalis W83 was separated in a 15% polyacrylamide gel containing 8 M urea; RNAs were transferred to nylon membranes by electroblotting and analyzed using biotinylated synthetic DNA probes specific to repeat and spacer sequences. “+” probes have a direction consistent with the direction of cas gene transcription (identical for all). “−” probes are complementary to “+” probes. Arrows to the right of each gel indicate the expected sizes of crRNA processing products, as follows: crRNA, mature crRNA; 1×, single repeat-spacer unit; and 2×, double repeat-spacer unit.