Fig 4.

Analysis of the contribution of each CSP to cspA and cspB cold induction. The promoter regions of cspA (pRM1) (A) and cspB (pRM4) (B) were cloned into pRKlacZ290 in front of a lacZ reporter gene, and the constructs were introduced into C. crescentus NA1000, ΔcspA, ΔcspB, ΔcspC, and ΔcspD strains. Expression was determined by measuring β-galactosidase activity at 30°C and 1 h, 2 h, and 5 h at 10°C. Relative expression was obtained by dividing Miller units from each time point at 10°C by the units at 30°C. The results shown are the averages of at least three experiments. Error bars indicate standard deviations. Expressions of cspA in the ΔcspC mutant and of cspB in the ΔcspC and ΔcspD mutants after 2 h were statistically different relative to the wild-type strain according to parametric unpaired t test (P < 0.05).