Chemical Ecology

We are interested in better understanding how chemicals control behavior. Nematodes provide a rich subject for chemical ecology, because they function in a wide range of environments and have relatively simple behaviors. Although we have had several interesting collaborative projects over the years, our primary organism for chemical ecology has been C. elegans. Despite the wealth of genetic, cellular, and anatomical information, less is known about C. elegans chemistry. For example, the existence of a pheromone that induces a dauer larval stage specialized for dispersal had been known for nearly 30 years before the first dauer pheromone was identified [Jeong et al., 2005].  Several related compounds are made by C. elegans that regulate dauer, and the next two that were discovered were ~100x more potent than the originally described compound [Butcher et al., 2007]. In collaboration with the Sternberg and Schroder labs, we discovered the mating pheromone for C. elegans and showed that it is a mixture of small molecule ascarosides that overlap with the known dauer pheromones [Srinivasan et al., 2008].

We discovered that the same set of pheromones regulate both development and adult mating behavior. At the time of this paper (Srinivasan et al., 2008), these were all the known ascarosides. Now there are hundreds, most of which we known almost nothing about.

We discovered that the same set of pheromones regulate both development and adult mating behavior. At the time of this paper (Srinivasan et al., 2008), these were all the known ascarosides. Now there are hundreds, most of which we known almost nothing about.

C. elegans utilizes an extensive chemical “language” that allows individuals to communicate and regulates basic behaviors such as feeding, mating, and population density control [Edison, 2009]. Hundreds of nematode ascarosides are now known [Ludwig and Schroeder, 2013], and some receptors have been identified [e.g. McGrath et al., 2011]. We still know very little about how the components work together, how the chemical signals are regulated, and receptors and other gene products that transduce signals into behavior.

We are working to understand the environmental factors that control ascaroside expression and to identify additional ascarosides in other nematode species. This information will not only add to the extensive scientific knowledge of C. elegans but may provide important new clues for the biological control of other nematode parasites of plants or animals. We are also taking a metabolomics approach to this problem and are developing a new large-scale project to map the C. elegans metabolome. The information that we obtain from this study will help us understand the biosynthetic pathways and genetic regulation associated with ascaroside signaling and function.

We have recently published an open access review paper that describes different approaches and strategies to chemical ecology studies.

Relevant Publications: