Written in Spring 2018

Introduction

Caenorhabditis elegans are considered a model organism because of their fast reproduction rate, short development period, and transparency, all factors that make them easy to study in the lab. Thus, much research that pertains to humans and animals is first done on C. elegans. What interested our group in particular was the chemosensation of C. elegans, and their behavior in response to various chemicals in their environment.

We were offered the chance to use Rhizobium leguminosarum, a nitrogen fixing bacteria, in our study, so we decided to study the reaction of C. elegans to nitrogen in their environment. Because nitrogen is a waste product produced by C. elegans (Eisenmann 2005), we hypothesized that as higher concentrations of nitrogen were introduced to an enclosed space, C. elegans would exhibit a behavioral response. Our specific prediction was that the C. elegans would move away from the nitrogen source.

Discussion

While our results were not significant, and thus our hypothesis was rejected, we did see an interesting trend in our data. In the first experimental group, there was a more visibly pronounced movement away from the R. leguminosarum than in the control or second experimental groups. This could indicate that only certain levels of nitrogen repel C. elegans, which could be an evolutionary adaptation to prevent them from avoiding areas that are nitrogen-rich but that do not necessarily contain waste materials. However, this is just a speculation and further research would be needed to verify this claim.

Some limitations in our study included lack of measurements for some time slots, a small number of plates used, and the fact that we chose 10μL and 100μL as our R. leguminosarum measurements randomly, and different levels of the bacteria may have had a significant effect. Future research should take these limitations into account, and could investigate C. elegans behavior around other waste particles. Research in this area could assist with conservation and health initiatives, as it could reveal the behavior of animals around waste products. It could also shed light on issues caused by pollution and inadequate spacing in and cleaning of enclosures for animals in captivity.

References

Eisenmann, D. M., Wnt signaling (June 25, 2005), WormBook, ed. The C. elegans Research

Community, WormBook, doi/10.1895/wormbook.1.7.1, http://www.wormbook.org.

Tsunekage, T.  (2018). Lab 3 – Introduction to Caenorhabditis elegans. Retrieved March 19,

2018.