C. elegans outside the Petri dish

Abstract

The roundworm Caenorhabditis elegans has risen to the status of a top model organism for biological research in the last fifty years. Among laboratory animals, this tiny nematode is one of the simplest and easiest organisms to handle. And its life outside the laboratory is beginning to be unveiled. Like other model organisms, C. elegans has a boom-and-bust lifestyle. It feasts on ephemeral bacterial blooms in decomposing fruits and stems. After resource depletion, its young larvae enter a migratory diapause stage, called the dauer. Organisms known to be associated with C. elegans include migration vectors (such as snails, slugs and isopods) and pathogens (such as microsporidia, fungi, bacteria and viruses). By deepening our understanding of the natural history of C. elegans, we establish a broader context and improved tools for studying its biology.DOI: http://dx.doi.org/10.7554/eLife.05849.001

Caenorhabditis elegans responses to bacteria from its natural habitats

“…By focusing our sampling efforts on one location and one year, we sought to minimize the influences of other types of variation that may influence bacterial community composition and C. elegans response to microbes (7,9). For each sample, we recorded: (i) presence or absence of C. elegans; (ii) the population size (number of nematodes); and (iii) the population state (i.e., whether they were larvae and reproductive adults associated with proliferation or growth-arrested dauer larvae (the nonproliferating dispersal stage for many nematodes) (7,9 to play a role at the initial inoculation of a rotting apple (7,9), as well as at the time of exit and dispersal in search of a more optimal bacterial milieu, once the population had proliferated and exhausted the resource. The assessment of nematode population in each sample was used to assign a nematode population score (log scale bins) to correlate bacterial composition with nematode population growth.…”

“…Rotting fruits and vegetation were collected and assessed for the presence of C. elegans nematodes as previously described (7,9). Briefly, the samples were collected in plastic bags and transported back to the laboratory.…”

“…The nematode Caenorhabditis elegans is a typical example of a model organism that has been disconnected from its natural ecology: although the species has been studied intensively in the laboratory for half a century, its habitat and natural ecology-what it naturally feeds on, its natural predators and pathogens, and its adaptive responses to its environmental and biological challengesare only now being determined (6)(7)(8)(9)(10)(11). Nematodes such as C. elegans have long been known to feed on bacteria that proliferate on decaying organic material, but the specific bacterial species that C. elegans encounters in the wild have not been comprehensively studied.…”

Oxygen-induced social behaviours inPristionchus pacificushave a distinct evolutionary history and genetic regulation fromCaenorhabditis elegans

“…Specifically, the border of the bacterial lawn is thicker and consumes more oxygen [13], whereas the oxygen concentration in clumps decreases even further owing to consumption by the nematodes [15]. Because C. elegans lives in an oxygen-variable environment in nature [9], where oxygen levels can fluctuate from 21% to anaerobic levels [16,17], avoidance of 21% oxygen has been proposed to be beneficial in these environments in order to escape surface exposure and enable accumulation on bacterial food sources [18].…”

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“…In the last few years, different studies have focused on the characterization of wild bacterial food sources and their impact on C. elegans metabolism [36][37][38]. For example, the Gram-positive bacterium B. subtilis has been used as an alternative worm diet in a number of studies.…”