Dietary Supplementation of Polyunsaturated Fatty Acids in <em>Caenorhabditis elegans</em>

Abstract

Fatty acids are essential for numerous cellular functions. They serve as efficient energy storage molecules, make up the hydrophobic core of membranes, and participate in various signaling pathways. Caenorhabditis elegans synthesizes all of the enzymes necessary to produce a range of omega-6 and omega-3 fatty acids. This, combined with the simple anatomy and range of available genetic tools, make it an attractive model to study fatty acid function. In order to investigate the genetic pathways that mediate the physiological effects of dietary fatty acids, we have developed a method to supplement the C. elegans diet with unsaturated fatty acids. Supplementation is an effective means to alter the fatty acid composition of worms and can also be used to rescue defects in fatty acid-deficient mutants. Our method uses nematode growth medium agar (NGM) supplemented with fatty acidsodium salts. The fatty acids in the supplemented plates become incorporated into the membranes of the bacterial food source, which is then taken up by the C. elegans that feed on the supplemented bacteria. We also describe a gas chromatography protocol to monitor the changes in fatty acid composition that occur in supplemented worms. This is an efficient way to supplement the diets of both large and small populations of C. elegans, allowing for a range of applications for this method. Video LinkThe video component of this article can be found at

Mono-unsaturated fatty acids link H3K4me3 modifiers to C. elegans lifespan

“…The fatty acid supplementation protocol was adapted from 40 with the following modifications. To facilitate fatty acid dissolution, the detergent Tergitol (type NP-40, Sigma-Aldrich) was added to a final concentration of 0.001% in liquid NGM agar media for both non-supplemented and supplemented plates prior to autoclaving.…”

Glucose Induces Sensitivity to Oxygen Deprivation and Modulates Insulin/IGF-1 Signaling and Lipid Biosynthesis inCaenorhabditis elegans

“…Fatty acid supplementation was conducted as described (Deline et al 2013). Briefly, NGM containing 0.1% Tergitol (NP-40) was autoclaved and cooled to 55°, after which oleic acid sodium salt (sodium oleate, Nu-Chek Prep) was added to a final concentration of 300 mM.…”

“…To determine if supplemental feeding of a specific fatty acid could rescue the anoxia sensitivity induced by glucosesupplementation, animals were raised on control media or on media supplemented with 0.3 mM sodium oleate from the L1 larval stage to 1-day-old adults (Deline et al 2013). Oleate supplementation did rescue the anoxia sensitivity of daf-2; fat-6; fat-7 mutant animals but not for the other genotypes tested Figure 1 A glucose-supplemented diet negatively impacts C. elegans ability to survive anoxia and paraquat exposure.…”

“…This may be due to the fact that fatty acid composition differs between the different mutants (Brock et al 2007;Shi et al 2013). To improve uptake of the oleate, we opted to not chronically feed the animals both glucose and oleate simultaneously; rather, animals were raised on the fatty acid supplemented media to maximize uptake and then transferred as adults to 0.5% glucose media and allowed to eat for 1 hr before being exposed to 24 hr of anoxia (Deline et al 2013). This difference in methodology may explain why the daf-2; fat mutants fed glucose for 1 hr, as opposed to being raised on glucose, had a higher anoxia survival rate ( Figure 4C compared to Figure 2D).…”

RNAi-based biosynthetic pathway screens to identify in vivo functions of non-nucleic acid–based metabolites such as lipids

“…The Watts lab has described an alternative method in which feeding plates containing lipids are made by mixing the lipids into the agar in the presence of tergitol, a nonionic surfactant 35 .…”