Effects of attractant concentration on pirouetting response of Caenorhabditis elegans

Abstract

The nematode Caenorhabditis elegans (C. elegans) use a pirouetting motion to reorientatethemselves with respect to the concentration gradient of the attractant. Thenumber of pirouettes performed by C. elegans during a three-minute span in the presenceof the attractant sodium acetate (NaOAc) was counted. Two separate trials wereperformed. In trial one, 0.5 M, 1.0 M, and 1.5 M treatments of NaOAc and 0.0 M watercontrols were used. In trial two, 0.5 M, 1.5 M, and 3.0 M treatments of NaOAc and 0.0 Mwater controls were used. Individual worms were followed and the number of pirouettesperformed was counted. In trial one, the results showed a gradual decrease in the numberof pirouettes performed as NaOAc concentration increased. In trial two, there was noevident trend in the results. By combining the results of both trials, we see that as theNaOAc concentration increased from 0.5M to 1.5M, there was a gradual decrease in theaverage number of pirouettes, but at 3.0M, there was a spike in the number of pirouettes.Our findings suggest that an increase in the concentration of NaOAc causes a decrease inthe number of pirouettes performed by C. elegans, but beyond a certain, optimumconcentration, toxicity may cause an increase in the number of pirouettes.