FIG. 3.

Slot blot analysis of atpB mRNA in response to environmental acidification. (A) Total RNA was isolated from S. sobrinus 6715 and SL1 and S. mutans UA159 grown in the chemostat under the conditions indicated in the figure (s.s., steady state). Hybridization was performed with internal fragments of the S. sobrinus and S. mutans atpB genes against DNA from the parent organism. RNase-treated samples were used as controls (data not shown). (B) Bar graph of atpB mRNA levels as measured by densitometry.