Fig. 7: Modulations in C. elegans SL metabolism affect survival after Bt247 infection.
A Overview of SL metabolism in C. elegans. C. elegans produces sphingoid bases which are derived from a C17 iso-branched fatty acid and are thus structurally distinct from those of other animals with mainly straight-chain C18 bases40. C. elegans SLs consist of a sphingoid base backbone derived from C15iso-CoA and serine, which is N-acylated with fatty acids of different lengths as well as different functional groups at the terminal hydroxyl group. Dihydroceramides (DhCers) are formed from C17iso sphinganine and fatty acids or 2-hydroxy fatty acids. Desaturation at the 4th carbon yields ceramides (Cers), which are the precursors of complex SLs such as sphingomyelin (SM) and glucosylceramide (HexCer). Mutants of SL metabolism genes in bold were tested in survival assays shown in (C). B Schematic survival comparing N2 wildtype (solid line) versus mutant strains (dashed lines), the difference of the area under the survival curve (AUC) is shaded in brown when the mutants are more susceptible to the infection than the control and in green when the mutants are more resistant to the infection. C Heatmap represents the ΔAUC of the survival of the C. elegans SL metabolism mutants versus average of the wildtype N2 strain. Each box represents an independent experiment, consisting of three to four technical replicates (individual bars). The intensity of the bar colour reflects the overall summary across all experiments, while the statistical analysis was performed separately for each experiment. Statistical analyses were carried out using the GLM framework with a binomial distribution. All tests were two-sided, and p-values were adjusted for multiple comparisons using the Bonferroni correction. Significance is indicated as *p < 0.05, **p < 0.01, ***p < 0.001. Each individual survival curve can be found in Fig. S17A, B. Source data and exact p-values are provided in Supplementary Data 12.
