Duration of the lag phase and maximum specific growth rate at 43°C and pH 4.5 of <i>S.</i> Typhimurium previously exposed to heat and acid shock.

*<p>mean±standard deviation of 3 independent replicated experiments.</p

Network representation of genes up- and down-regulated during and after the heat shock.

<p>Modularity of networks of down-regulated genes was significantly lower than that of up-regulated networks. The induction of genes belonging to a metabolic pathway or cellular function was more synchronized than their down-regulation because of the hysteretic transcriptional response or persistence of the induction of the majority of genes induced by the heat shock once the temperature is set back to 25°C. Different colours represent different modules in each network.</p

Modularity quantification in sub-networks extracted from the <i>Salmonella</i> genome scale network containing those genes differentially expressed during and after the heat treatment and comparison with random extracted sub-networks with the same number of genes.

1<p>Modularity coefficient from 0 to 1 (maximum modularity).</p>2<p>Mean value and standard deviation of the modularity coefficient of 10 random networks.</p>*<p>Significant: Smaller than the mean value minus 3 times the standard deviation of random networks.</p

Fold change of transcript levels of genes during heat stress and immediately and 30 minutes after temperature was set back at 25°C that exhibited hysteresis and encoded for heat shock proteins (A), for DNA repair (B) for products involved in protein stabilization (C) or were encoded in plasmids (D).

<p>Down-regulated genes throughout the experiment were associated with non stress specific response such as pathogenesis (E) and motility (F). Genes represented in each plot showed a similar tendency; they are listed by the side of each plot but not differentially represented.</p

Number of genes up- (green) and down- (red) regulated in <i>S</i>. Typhimurium under acid and heat stressing conditions and immediately and 30 min after removing the stressing conditions.

<p>Few genes were affected by acid stress (A) while transcription of a large number of genes was altered under heat stress (B). Majority of up-regulated genes under heat stress remained up-regulated 30 minutes after stress condition ceased. Black numbers and solid lines show up- and down- regulated genes maintained throughout the experiment.</p