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. 2012 Jun 7;7(6):e38584. doi: 10.1371/journal.pone.0038584

Figure 6. Hsp21 regulates intracellular glycerol, glycogen and trehalose homeostasis.

Figure 6

(A) Measurement of intracellular glycerol levels in the wild type (Wt), the hsp21Δ/Δ mutant or the hsp21Δ/Δ::HSP21 complemented strain after growth for 24 h in SD medium (control) at 30°C, SD medium supplemented with 0.4 mM menadione (+menadione) at 30°C, SD medium supplemented with 1.5 M NaCl (+NaCl) at 30°C, SD medium at 42°C (42°C), or SD medium supplemented with 1.5 M NaCl at 42°C (+NaCl, 42°C). Glycerol levels are plotted in nM normalized against wet weight (g). Results are the mean ± SD of three independent experiments. **P<0.01 and *P<0.05 compared with the wild type and hsp21Δ/Δ::HSP21 complemented strain. (B) Estimation of glycogen content with iodine vapour for the wild type (Wt), the hsp21Δ/Δ mutant or the hsp21Δ/Δ::HSP21 complemented strain after cultivation on SD agar (control) at 37°C, SD agar supplemented with 0.4 mM menadione at 37°C (+menadione), SD agar supplemented with 1.5 M NaCl (+NaCl) at 37°C, SD agar at 42°C (42°C), or SD agar supplemented with 1.5 M NaCl at 42°C (+NaCl, 42°C). The darker the colour of a colony, the more intracellular glycogen is present. Experiments were performed twice in duplicate yielding similar results. Representative pictures are shown. (C) Measurement of intracellular trehalose levels in the wild type (Wt) and the hsp21Δ/Δ mutant strain. Growth conditions were the same as described for panel (A). Trehalose levels (nmol trehalose per mg total cell protein) are indicated relative to the Wt grown under control conditions. Results are the mean ± SD of five (control; +NaCl; 42°C) or two (+menadione; +NaCl, 42°C) independent experiments. *P<0.05 compared with the wild type strain under the same condition.