Figure 6. GAL lncRNAs promote faster growth and adaptation to a changing environment.

(A) Growth curves of wild type and lncRNAΔ cells during a carbon source switch. Cell density was measured by absorbance (A600_nm) across a glucose to galactose switch in synthetic complete (SC) media. Results are presented as the mean of 6 biological replicates with the SEM. (B) Growth curves of wild type and lncRNAΔ cells during a mock (glucose to glucose) shift. Doubling times (t²) were determined by fitting to an exponential growth curve in GraphPad Prism whereas lag times were calculated using DMFit (Baranyi and Roberts, 1994) (http://www.combase.cc/tools/). (C) RNase H1 represses growth of wild type cells during a glucose to galactose shift. Doubling and lag times of cells were determined as above. (D-E) Competition assay of wild type and lncRNAΔ cells during a carbon source switch. A TRP1 allele was integrated into the trp1-63 locus of the lncRNAΔ strain to differentiate from wild type. Colony forming units (c.f.u.’s) were determined on both rich and selective media at each time point with the proportion of wild type or lncRNAΔ cells in the culture corresponding to the number of trp- or trp+ cells over the total. Results represent the mean of 3 biological replicates with SEM. (F-G) Competition assays of trans-lncRNA versus lncRNAΔ (F) and cis-versus trans-lncRNA strains (G) reveals equal benefit of trans versus cis-encoded GAL lncRNAs during a carbon source shift. Competition assays were performed as above.