Starvation-induced collective behavior in C. elegans.

Alexander B Artyukhin,Joshua J Yim,Leon Avery,Mi Cheong Cheong

doi:10.1038/srep10647

Abstract

We describe a new type of collective behavior in C. elegans nematodes, aggregation of starved L1 larvae. Shortly after hatching in the absence of food, L1 larvae arrest their development and disperse in search for food. In contrast, after two or more days without food, the worms change their behavior—they start to aggregate. The aggregation requires a small amount of ethanol or acetate in the environment. In the case of ethanol, it has to be metabolized, which requires functional alcohol dehydrogenase sodh-1. The resulting acetate is used in de novo fatty acid synthesis, and some of the newly made fatty acids are then derivatized to glycerophosphoethanolamides and released into the surrounding medium. We examined several other Caenorhabditis species and found an apparent correlation between propensity of starved L1s to aggregate and density dependence of their survival in starvation. Aggregation locally concentrates worms and may help the larvae to survive long starvation. This work demonstrates how presence of ethanol or acetate, relatively abundant small molecules in the environment, induces collective behavior in C. elegans associated with different survival strategies.

Highlights

96 h expectation, we found that after brief initial dispersal starved L1 larvae aggregated on fresh agar plates as efficiently as they did on old, exhausted plates
We thoroughly washed the worms before pipetting on the plate to remove any soluble substances that they may have secreted up to this point. (We know there are many8.) We observed three distinct stages of worm behavior after L1 larvae were pipetted on a clean plate (Fig. 1)
We examined the behavior of starved daf-22 L1s, which lack all ascarosides commonly detected in wild type12. daf-22 encodes the peroxisomal 3-keto-acyl-CoA thiolase, which is necessary for peroxisomal β -oxidation of fatty acids and ascaroside biosynthesis[13,14,15]

Summary

Introduction

96 h expectation, we found that after brief initial dispersal starved L1 larvae aggregated on fresh agar plates as efficiently as they did on old, exhausted plates. We hypothesized that the density dependence of the disks-to-stripes transition mentioned earlier may result from the fact that more worms on the plate consume a given amount of alcohol faster. We tested three sodh-1 alleles and found that worms carrying any of them did not aggregate in the presence of 0.1% ethanol (Fig. 5 and data not shown).

Results

Conclusion