FIG. 2.

Northern analysis of flhDC mRNA in S. liquefaciens (performed as described in Materials and Methods). (A) The Northern blot contains RNA from MG1 cells isolated from the edge of a swarming colony (lane a), liquid-grown MG1 mid-log-phase (OD₄₅₀ = 0.4) cells (lane b), liquid-grown MG1 late-log-phase (OD₄₅₀ = 1.2) cells (lane c), liquid-grown MG3/pMG600 mid-log-phase cells sampled 20 min after addition of 50 μM IPTG (lane d), liquid-grown MG3/pMG600 mid-log-phase cells sampled 20 min after addition of 200 μM IPTG (lane e), and liquid-grown MG3/pMG600 mid-log-phase cells grown in the absence of IPTG (lane f). The sizes of the two transcripts are indicated at the left. (B) Photograph of the ethidium-stained gel used for Northern blotting. 16S and 23S rRNA bands are indicated. (C) Radioactive signals emitted from specific bands and quantified by the use of an electronic instant-imager device. The relative values are averages of two independent Northern blots. Bars, standard deviations.