Fig. 6. AcrA expression in wild-type and acg- cells. (A,B) AcrA expression detected by in-situ hybridization. Wild-type cells were starved on dialysis membrane supported by PB agar. AcrA mRNA was visualized in migrating slugs (A) and mid-culminants (B) by in-situ hybridization to a DIG-labelled AcrA RNA-probe. (C,D) Wild-type (C) and acg- (D) cells were transformed with vector AcrA::ala-gal, which contains a gene fusion of the AcrA promoter and ala-gal, which encodes a stable form of ß-galactosidase. Migrating slugs were fixed and stained with X-Gal to visualize ß-galactosidase activity. AcrA-ile-gal-transformed cells yielded the same pattern, but the staining intensity was very low (data not shown). Scale bars: 100 µm.