Table 1.

Role of C. elegans orthologs of sphingolipid metabolism in radiation-induced apoptosis. The family of sphingolipids and associated metabolic enzymes involved in ceramide intermediary metabolism, conserved from yeast to humans is shown on at left. Thick arrows designate the de novo ceramide synthetic pathway. Enzymes listed in bold indicate C. elegans enzymes for which lf alleles were screened for germ cell apoptosis at 36 hours post–120 Gy (shown at right). Apoptosis inhibition (+) was interpreted relative to WT-irradiated controls. Asterisks indicate hypersensitivity to radiation-induced apoptosis. At least 20 worms were counted per allele. SPT, serine palmitoyltransferase; 3-KSR, 3-ketosphinganine reductase; CerS, ceramide synthase; DES, dihydoceramide desaturase; CerK, ceramide kinase; SMase, sphingomyelinase; CDase, ceramidase; SphK, sphingosine kinase; S1PPL, S1P lyase.