Effect of the diet type and temperature on the C. elegans transcriptome.

The transcriptomes of model organisms have been defined under specific laboratory growth conditions. The standard protocol for Caenorhabditis elegans growth and maintenance is 20°C on an Escherichia coli diet. Temperatures ranging from 15°C to 25°C or feeding with other species of bacteria are considered physiological conditions, but the effect of these conditions on the worm transcriptome has not been well characterized. Here, we compare the global gene expression profile for the reference Caenorhabditis elegans strain (N2) grown at 15°C, 20°C, and 25°C on two different diets, Escherichia coli and Bacillus subtilis . When C. elegans were fed E. coli and the growth temperature was increased, we observed an enhancement of defense response pathways and down-regulation of genes associated with metabolic functions. However, when C. elegans were fed B. subtilis and the growth temperature was increased, the nematodes exhibited a decrease in defense response pathways and an enhancement of expression of genes associated with metabolic functions. Our results show that C. elegans undergo significant metabolic and defense response changes when the maintenance temperature fluctuates within the physiological range and that the degree of pathogenicity of the bacterial diet can further alter the worm transcriptome.