Figure 1.

ACS-22/FATP1 and DGAT-2 are required for TAG synthesis and LD expansion in daf-22 animals. (A–F) Oil red O staining of fixed larval stage L4 animals. Expanded LDs >3 µm in diameter (black arrows) were found in daf-22 mutant animals (B) but were absent in wild-type (A), acs-22 (C), daf-22; acs-22 (D), dgat-2 (E), and daf-22; dgat-2 (F) animals. (G) Quantification of TAG by gas chromatography–mass spectroscopy. Synthesis of excess TAG in daf-22 mutant animals required ACS-22/FATP1 and DGAT-2. Results were means ± SEM of measurements from three to six independent populations of animals of each genotype. In a pairwise t test, P < 0.05 between wild-type (WT) and daf-22 samples (asterisks); P > 0.1 between WT and all other samples. (H) Quantitation of palmitic acid (C16:0) absorption, synthesis, elongation, and maternal deposition by ¹³C isotope labeling. Results were means ± SEM from six independent populations of each strain of animals. (I) The acs-22 gene is expressed in multiple tissues including the intestine. The bicistronic acs-22p::acs-22::SL2::gfp transgene, which expressed ACS-22 and GFP independently under the control of the acs-22 promoter, rescued the loss of acs-22 function and restored expanded LD (white arrowheads) in daf-22; acs-22 mutant animals. An L4 animal is shown. (J) The dgat-2 gene is expressed in the intestine. Overexpression of dgat-2 was sufficient for promoter LD expansion in wild-type animals. An L4 animal is shown. Bars: (A–F) 20 µm; (I and J) 10 µm.