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Open Access

Food size and cGMP affects feeding behaviour in Pristionchus pacificus

  • Silvina Kroetz1Email author,
  • Jagan Srinivasan2,
  • Paul Sternberg2 and
  • Ray L Hong1
Journal of the International Society of Sports Nutrition20118(Suppl 1):P26

Published: 7 November 2011


Locomotory BehaviorDependent Protein KinaseReversal RateLocomotion PatterncGMP Dependent Protein Kinase


Animals evolved different locomotory behaviors in order to find food in their environment. I studied the food seeking locomotion and pharyngeal pumping of nematodes Pristionchus pacificus on various food sources.


For this study I used P. pacificus PS312, and the mutants Ppa-egl-4, which is a null mutation in the cGMP dependent protein kinase, and Ppa-obi-1, which is an oriental beetle pheromone insensitive mutant, and the double mutant Ppa-egl-4;obi-1. I tested these strains on plates containing no food and on E.coli OP50, HB101, Caulobacter crescentus (NA1000) and Bacillus subtilis. I analyzed locomotory behavior using an automated tracking system, and I obtained pharyngeal pumping data by visually counting with a microscope at 80X magnification.


I observed that locomotion of the strains differed on plates with no food and plates with food. On plates with no food, P. pacificus PS312 displayed a higher reversal rate compared to the Ppa-obi-1 strain. The double mutant egl-;obi-1 displayed similar locomotion patterns to Ppa-obi-1 on HB101. Furthermore, when I compared PS312 pharyngeal pumping rates on and off food on two different size bacteria E. coli and C. crescentus, results showed a significant increased rate on PS312 on C. crescentus, which was the smaller bacteria.


My results indicated that Ppa-obi-1 may act in either a parallel pathway, or upstream of Ppa-egl-4. PS312 raised on C. crescentus (NA1000) for 3 generations retained memory of the food experience regardless of whether they were removed from food or placed back on NA1000 as food. Increasing bacterial size using mutant C. crescentus strains seem to further decrease pumping rates off food. My data suggest strong roles for food sizes and cGMP sensing proteins in maintaining feeding patterns in P. pacificus.

Authors’ Affiliations

Department of Biology, California State University, Northridge, USA
Division of Biology, California Institute of Technology, Pasadena, USA


© Kroetz et al; licensee BioMed Central Ltd. 2011

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.