Caenorhabditis elegans Battling Starvation Stress: Low Levels of Ethanol Prolong Lifespan in L1 Larvae

Abstract

The nematode Caenorhabditis elegans arrests development at the first larval stage if food is not present upon hatching. Larvae in this stage provide an excellent model for studying stress responses during development. We found that supplementing starved larvae with ethanol markedly extends their lifespan within this L1 diapause. The effects of ethanol-induced lifespan extension can be observed when the ethanol is added to the medium at any time between 0 and 10 days after hatching. The lowest ethanol concentration that extended lifespan was 1 mM (0.005%); higher concentrations to 68 mM (0.4%) did not result in increased survival. In spite of their extended survival, larvae did not progress to the L2 stage. Supplementing starved cultures with n-propanol and n-butanol also extended lifespan, but methanol and isopropanol had no measurable effect. Mass spectrometry analysis of nematode fatty acids and amino acids revealed that L1 larvae can incorporate atoms from ethanol into both types of molecules. Based on these data, we suggest that ethanol supplementation may extend the lifespan of L1 larvae by either serving as a carbon and energy source and/or by inducing a stress response.

To Grow or Not to Grow: Nutritional Control of Development DuringCaenorhabditis elegansL1 Arrest

“…The critical difference between the two buffers is ethanol: cholesterol dissolved in ethanol is added to S-basal, resulting in a final concentration of 0.1% (20 mM) ethanol. As little as 1 mM ethanol extends starvation survival to a similar degree, as do n-propanol and n-butanol but not methanol or isopropanol (Castro et al 2012). Clarke and colleagues showed that pharyngeal pumping is necessary for ethanol to extend survival and that it is used as a carbon source to synthesize fatty acids and amino acids (Castro et al 2012).…”

“…As little as 1 mM ethanol extends starvation survival to a similar degree, as do n-propanol and n-butanol but not methanol or isopropanol (Castro et al 2012). Clarke and colleagues showed that pharyngeal pumping is necessary for ethanol to extend survival and that it is used as a carbon source to synthesize fatty acids and amino acids (Castro et al 2012). In this sense the larvae are not truly starved, but the carbon source alone is not sufficient to initiate larval development.…”

“…Mutation of tbc-2, rme-1, or rme-6 reduces embryonic yolk protein abundance, and each mutant also has reduced starvation survival (Chotard et al 2010). It is unknown if starvation survival of these yolk mutants can be rescued by ethanol in the buffer, which can be used as a carbon source for fatty acid synthesis (see Environmental factors affecting starvation survival) (Castro et al 2012). Autophagy also appears to provide energy during starvation, as RNAi of bec-1/Atg6/Vps30/Beclin1 reduces starvation survival (Kang et al 2007).…”

Reproductive and Locomotory Capacities of Caenorhabditis elegans Were Not Affected by Simulated Variable Gravities and Spaceflight During the Shenzhou-8 Mission

“…3), with a speed of *0.02 mm/ s, a frequency of *10 reversals in 2 min, and a rate of *30 body bends in 30 s on Day 2. Since earlier-stage nematodes may have a more sensitive response to stress (Castro et al, 2012), we then investigated the response of larval nematodes to hypergravity and microgravity. After 6 h of treatment from L1 and L4 stages ( Fig.…”

A Screenable <em>In Vivo</em> Assay for Mitochondrial Modulators Using Transgenic Bioluminescent <em>Caenorhabditis elegans</em>

“…By carrying out the starvation in S complete medium as opposed to M9, the hatching nematodes are provided with a carbon source (ethanol), so that larvae do not develop but are not completely starved. 27,28 It has also been shown that arrested L1's are primed for rapid response to food and normal L1 growth rate is achieved within 3 hr after food becomes available. 29 However, it the possibility that the starvation step may alter the metabolism of C. elegans cannot be excluded.…”