Interspecific nematode signals regulate dispersal behavior.
BACKGROUND
Dispersal is an important nematode behavior. Upon crowding or food depletion, the free living bacteriovorus nematode Caenorhabditis elegans produces stress resistant dispersal larvae, called dauer, which are analogous to second stage juveniles (J2) of plant parasitic Meloidogyne spp. and infective juveniles (IJ)s of entomopathogenic nematodes (EPN), e.g., Steinernema feltiae. Regulation of dispersal behavior has not been thoroughly investigated for C. elegans or any other nematode species. Based on the fact that ascarosides regulate entry in dauer stage as well as multiple behaviors in C. elegans adults including mating, avoidance and aggregation, we hypothesized that ascarosides might also be involved in regulation of dispersal behavior in C. elegans and for other nematodes such as IJ of phylogenetically related EPNs.


RESULTS
Liquid chromatography-mass spectrometry analysis of C. elegans dauer conditioned media, which shows strong dispersing activity, revealed four known ascarosides (ascr#2, ascr#3, ascr#8, icas#9). A synthetic blend of these ascarosides at physiologically relevant concentrations dispersed C. elegans dauer in the presence of food and also caused dispersion of IJs of S. feltiae and J2s of plant parasitic Meloidogyne spp. Assay guided fractionation revealed structural analogs as major active components of the S. feltiae (ascr#9) and C. elegans (ascr#2) dispersal blends. Further analysis revealed ascr#9 in all Steinernema spp. and Heterorhabditis spp. infected insect host cadavers.


CONCLUSIONS
Ascaroside blends represent evolutionarily conserved, fundamentally important communication systems for nematodes from diverse habitats, and thus may provide sustainable means for control of parasitic nematodes.
Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture (USDA-ARS), Gainesville, Florida, United States of America. fkaplan@ufl.edu
Fatma
F
Kaplan
Hans T
HT
Alborn
Stephan H
SH
von Reuss
Ramadan
R
Ajredini
Jared G
JG
Ali
Faruk
F
Akyazi
Lukasz L
LL
Stelinski
Arthur S
AS
Edison
Frank C
FC
Schroeder
Peter E
PE
Teal
D000819:Animal Communication; D000818:Animals; D002853:Chromatography, Liquid; D017077:Culture Media, Conditioned / Q000737:chemistry; D017931:DNA Primers / Q000235:genetics; D005431:Florida; D006017:Glycolipids / Q000737:chemistry / Q000494:pharmacology*; D006601:Hexoses / Q000737:chemistry; D007814:Larva / Q000187:drug effects / Q000502:physiology; D018551:Solanum lycopersicum / Q000469:parasitology; D013058:Mass Spectrometry; D015394:Molecular Structure; D009068:Movement / Q000187:drug effects / Q000502:physiology*; D009348:Nematoda / Q000502:physiology*; D016133:Polymerase Chain Reaction; D013045:Species Specificity
D017077:Culture Media, Conditioned; D017931:DNA Primers; D006017:Glycolipids; D006601:Hexoses; C009616:tyvelose