Fig 4.

Constitutive expression of chbC restored the growth defects of the rrp1^mut mutant. (a) The rrp1 mutant has decreased chbC transcript. The WT rrp1^mut, and rrp1^com strains were cultured at 34°C and pH 7.6 and harvested at the early stationary phase (∼10⁸ cells/ml). Total RNA was extracted for qRT-PCR. Data are expressed as expression of the rrp1^mut or rrp1^com transcripts relative to the wild-type level. Asterisks indicate that the difference between WT and rrp1^mut transcript levels was statistically significant at a P value of <0.01 (two-way ANOVA). (b) Constitutive expression of chbC rescues the growth defects of the rrp1^mut mutant. Growth curve experiments similar to those described for Fig. 2 were repeated using BSK-II and BSK-II_(−GlcNAc)+chitobiose media at 34°C and pH 7.6. Cell counting was repeated in triplicate with at least two independent samples, and the results are expressed as means ± SEM. Asterisks indicate that the difference between the rrp1^mut and rrp1^mut chbC⁺ strains in cell densities was statistically significant at a P value of <0.001.