FIG 2.

Mannitol addition concurrently increases mtlA expression and decreases mtlS expression. V. cholerae was grown to mid-log phase in minimal medium with 0.4% (wt/vol) mannitol (Mtl), glucose (Glu), sucrose (Suc), mannose (Man), or maltose (Mal) supplemented with an additional 0.4% mannitol (+Mtl) or an equal volume of water (+H₂O). (A) Cell lysates were subjected to both Northern blot analysis (for MtlS) and Western blot analysis (for MtlA). The relative intensity (RI) of each sample compared to the intensity of glucose plus H₂O (for MtlS analysis) or mannitol plus H₂O (for MtlA analysis) is shown beneath each band. Blots are representative of those from at least two independent experiments. (B, C) Total RNA was used for qRT-PCR analysis with primers specific to mtlA (B) or mtlS (C). The levels of mtlA and MtlS RNA were normalized (Norm.) to those of an endogenous 4.5S RNA control. Reported are the means and standard deviations from three biological replicates. P values are based on two-tailed unpaired t test. *, P < 0.05; NS, not significant.