Figure 2.

L1 starvation survival is reduced when ceramide levels are decreased, but it can be partially rescued with sphingoid base supplementation. (A) Ceramide levels are decreased in both sptl-2(lf) and lagr-1(lf); hyl-1(lf) double mutants [referred to CerS(rf)]. Total ceramide levels of mutants relative to that of wild type are shown in columns. Errors bars represent SE at each time point indicated. P values were calculated by Student’s t-test. (B) Survival rates of wild type, sptl-2(lf) ± dietary supplementation, sptl-2(lf); sphk-1(ok1097), and two acs-20 mutants. The sptl-2(lf) defect was significantly suppressed by both dietary supplementation of 250 nM iso-branched d17iso-sphinganine (d17iso-SPA) and sphk-1(ok1097) mutation. Percentage survival is defined as the percentage of animals surviving to the third larval stage and beyond on food after L1 worms were starved in S-basal buffer for the indicated time. The starvation survival data for wild type and sptl-2(lf) are the same as that presented in Figure 1B. (C) The mean survival rate of individual replicates was calculated through OASIS software. The average of the mean survival rate of all-individual replicates for each strain is presented here. *The statistical analyses (P value) to assess the difference between the mean survival rates were conducted using Student’s t-test. ^a,bP values indicate the significance of the difference from wild type (^aP) and sptl-2(ok2753) mutant animals (^bP), respectively. Raw data and detailed statistical analysis data for individual starvation survival experiments for figure 1B are presented in Table S1.