Regulation of distinct attractive and aversive mechanisms mediating benzaldehyde chemotaxis in Caenorhabditis elegans.
Olfactory-mediated chemotaxis in nematodes provides a relatively simple system to study biological mechanisms of information processing. Analysis of the kinetics of chemotaxis in response to 100% benzaldehyde revealed an initial attractive response that is followed by a strong aversion to the odorant. We show that this behavior is mediated by two genetically separable attraction- and aversion-mediating response pathways. The attraction initially dominates behavior but with prolonged exposure habituation leads to a behavioral change, such that the odorant becomes repulsive. This olfactory habituation is susceptible to dishabituation, thereby re-establishing the attractive response to the odorant. Re-examination of the putative olfactory adaptation mutant adp-1(ky20) revealed that the phenotype observed in this line is due to a supersensitivity to a dishabituating stimulus, rather than a defect in the adaptation to odorants per se. A modified benzaldehyde chemotaxis assay was developed and used for the isolation of a mutant with a specific defect in habituation kinetics, expressed as a persistence of the attractive response.
Nuttley
W M
WM
Department of Anatomy and Cell Biology, University of Toronto, Toronto, Ontario M5S 1A8, Canada. bill.nuttley@utoronto.ca
Harbinder
S
S
van der Kooy
D
D
D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D001547:Benzaldehydes / Q000494:pharmacology*; D017173:Caenorhabditis elegans / Q000235:genetics / Q000502:physiology*; D002630:Chemotactic Factors / Q000494:pharmacology*; D002633:Chemotaxis / Q000187:drug effects*; D006185:Habituation, Psychophysiologic / Q000502:physiology; D007700:Kinetics; D009154:Mutation / Q000502:physiology
D001547:Benzaldehydes; D002630:Chemotactic Factors; C032175:benzaldehyde