PMC

(A) Key silicone features of the A160 valve. (B) Normal diaphragm and distorted diaphragm with loss of elasticity and blister. Effect on O-ring after absorbing moisture and losing elasticity. (C) Valve with normal function. (D) Valve with gap in seal, allowing continuous flow.

Assays of triR-lacZ expression in various mutants. Expression of triR was assayed using pIJ7878 (triR-lacZ) introduced into the wild-type strain A34 (filled diamonds), the rhiR mutant A160 (filled squares), the bisR mutant A549 (open squares), the triR mutant A627 (filled triangles), and the cinI mutant A664 (open triangles). OD₆₀₀s measured using strain A34 are represented by open diamonds, and the growth rates of all the strains were similar.

Expression of rhiI-lacZ and rhiA-lacZ. The expression of rhiI-lacZ (pIJ7794) (A) or rhiA-lacZ (pIJ1769) (B) was analyzed by measuring β-galactosidase throughout growth of strains A34 (wild type), 8401 (strain A34 lacking pRL1JI), A160 (rhiR1::Tn5), and A721 (rhiI15::Tn5). The growth curves (OD₆₀₀) shown as broken lines correspond to those obtained with A34/pIJ7794 or A34/pIJ1769; the growth of the other strains was very similar. LSD, least significant difference.

Identification of AHLs produced by RhiI. AHLs extracted from spent medium were separated by TLC and detected by using an overlay of agar containing C. violaceum CV026. Lanes a and b contain extracts of spent culture supernatants from A. tumefaciens C58.00 carrying either pIJ7790 (carrying the rhiI15::Tn5 mutation) (lane a) or pIJ1089 (lane b). Results similar to those seen in lane a (no AHLs were detected) were found with C58.00 carrying no introduced plasmid. Lane c contains the synthetic standards C₆-HSL and C₈-HSL. Lanes d, e, and f contain extracts of spent culture supernatants from the R. leguminosarum bv. viciae strains A34 (wild type), A160 (rhiR1::Tn5), and A721 (rhiI15::Tn5), respectively.