A high-throughput behavioral screening platform for measuring chemotaxis by C. elegans

Area of Science:

• Neuroscience and Behavior
• Chemical Ecology
• Molecular Biology

Background:

• Plants produce diverse small molecules (SMs) influencing animal behavior.
• Nematodes possess chemosensory abilities to differentiate beneficial from harmful plant compounds.
• Olfactory valence, classifying chemical cues by value, is crucial for survival and shared across species.

Purpose of the Study:

• To develop an efficient platform for determining the olfactory valence of plant small molecules (SMs) using the model nematode Caenorhabditis elegans.
• To identify specific plant SMs that elicit attraction or repulsion in C. elegans.
• To investigate the genetic basis of chemosensory responses and signal integration in olfactory valence determination.

Main Methods:

• An integrated hardware-wetware-software platform utilizing multiwell plates, liquid handling, optical scanners, and custom software was employed.
• Screening of 90 plant SMs was conducted on wild-type Caenorhabditis elegans.
• Chemosensory transduction mutants were used to validate responses and identify genetically dependent SMs.

Main Results:

• The platform successfully identified 37 plant SMs that induced attraction or repulsion in wild-type C. elegans.
• Responses to these 37 SMs were absent in mutants with defects in chemosensory transduction.
• Genetic analysis revealed that for at least 10 SMs, the response valence results from integrating opposing chemosensory signals.

Conclusions:

• Caenorhabditis elegans serves as an effective model organism for discovering olfactory valence and identifying plant-derived natural products detected by the chemosensory system.
• Olfactory valence is often determined by integrating information from multiple chemosensory signals.
• This study provides a robust platform for advancing research in chemical ecology and neurobiology.