Figure 6.

elo3Δ erg6^ts has a sphingolipid composition characteristic for elo3Δ. (A) Sphingolipid synthesis in wild-type (FY1679a), erg6Δ (YRS1266), elo2Δ (YRS1265), elo3Δ (YRS1118), and the elo3Δ erg6Δ double mutant strain bearing a plasmid-borne copy of either ERG6 (elo3Δ ERG6, YRS1520) or erg6^ts (elo3Δ erg6^ts, YRS1519) was assessed by labeling cells at either 24 or 37°C with [³H]inositol for 2 h. Lipids were extracted, and label incorporated into the mild-base–resistant sphingolipid fraction was determined in comparison to label incorporated into the total lipid fraction. (B) Sphingolipid composition in strains of indicated genotype was analyzed by TLC and fluorography. Cells were labeled at either 24 or 37°C with [³H]inositol for 2 h, and mild-base–resistant lipids were separated by TLC. The position of different sphingolipid species is indicated to the left. MIPC, mannosyl-inositolphosphorylceramide; M(IP)₂C, mannosyl-diinositolphosphorylceramide. (C) Comparison of the levels of sphingolipid precursors in strains of indicated genotype. Cells were labeled at either 24 or 37°C with [³H]serine for 4 h, and mild-base–resistant lipids were separated by TLC. The position of sphingolipid precursors and mature sphingolipid species is indicated to the left. MIPC, mannosyl- inositolphosphorylceramide.