FIG. 2.

Transcription of virulence genes in wild-type and mutant GAS strains. (A) Growth curves showing times of isolation of RNA (arrowheads). Open triangles represent JRS4 (wild type), filled circles represent JRS550 (irr1), and filled squares represent JRS551 (covR1). (B) Hybridization of specific DNA probes to RNA harvested at the times indicated in panel A. On each filter, the left column contains 4 μg of RNA and the right column contains 0.4 μg of RNA. Duplicates are arranged vertically. Membranes were reacted with PCR-derived DNA probes internal to the coding region of the GAS virulence genes mga, emm, scpA, slo, hasA, ska, and sagA, as shown (Materials and Methods). A probe from rpsL was used to determine that equal amounts of RNA were loaded. Filters with all RNA samples were hybridized together. Results reported are representative of hybridizations from at least two independent RNA isolations.