Potential Nematode Alarm Pheromone Induces Acute Avoidance in Caenorhabditis elegans

Abstract

It is crucial for animal survival to detect dangers such as predators. A good indicator of dangers is injury of conspecifics. Here we show that fluids released from injured conspecifics invoke acute avoidance in both free-living and parasitic nematodes. avoids extracts from closely related nematode species but not fruit fly larvae. The worm extracts have no impact on animal lifespan, suggesting that the worm extract may function as an alarm instead of inflicting physical harm. Avoidance of the worm extract requires the function of a cGMP signaling pathway that includes the cGMP-gated channel TAX-2/TAX-4 in the amphid sensory neurons ASI and ASK. Genetic evidence indicates that the avoidance behavior is modulated by the neurotransmitters GABA and serotonin, two common targets of anxiolytic drugs. Together, these data support a model that nematodes use a nematode-specific alarm pheromone to detect conspecific injury.

The Grueneberg ganglion controls odor-driven food choices in mice under threat

“…It is therefore conserved throughout the animal kingdom 41,42 . For example, in the nematode Caenorhabditis elegans (C. elegans), stress linked to environmental conditions can impact food preferences when they are coupled with odorants 43 as well as with alarm pheromones and predator scents 44,45 . Interestingly, this worm modality is dependent on a specific olfactory subsystem composed of a pair of amphid wing cells of type C 46 (AWC).…”

Plant metabolism of nematode pheromones mediates plant-nematode interactions

“…the observed suppression of nematode migration towards roots, Therefore, we tested a series of combinations of ascr#18, which is directly excreted by the nematodes, and its most abundant plant metabolite, ascr#9, in a previously described quantitative chemotaxis population assay 38 (Fig. 5c).…”

“…Worms that remained in the center 0.5-cm-wide strip were not counted. The attraction index was calculated as (A -B/A + B), where A and B denote numbers of nematodes on the test solution side and mock solution side, respectively 38 . All experiments were independently performed four times.…”

Plasticity of pheromone-mediated avoidance behavior in C. elegans

“…Worms appear to avoid other putative pheromone components. Zhou et al found that the internal fluid from injured worms elicited repulsive behavior in adult hermaphrodites via the ASI and ASK chemosensory neurons (Zhou et al, 2017). The group also found that this internal fluid did not affect the lifespan of worms, suggesting that this fluid acts as not a harmful repellent chemical but as an alarm pheromone (Zhou et al, 2017).…”

“…Zhou et al found that the internal fluid from injured worms elicited repulsive behavior in adult hermaphrodites via the ASI and ASK chemosensory neurons (Zhou et al, 2017). The group also found that this internal fluid did not affect the lifespan of worms, suggesting that this fluid acts as not a harmful repellent chemical but as an alarm pheromone (Zhou et al, 2017). This potential pheromone was none of the known ascarosides but comprised at least three nonvolatile components (Zhou et al, 2017).…”