Genetic analysis of the bacterial choice preference in Caenorhabditis elegans

Abstract

In its natural habitat, Caenorhabditis elegans interacts with many different bacteria. Some of the bacteria are good food sources, while some of them are pathogenic. Recent data show that C. elegans uses odors produced by bacteria to identify food sources. However, no specific odorants had been identified. Moreover, the sensory neurons by which C. elegans senses and responds to the food remain unknown. In this study, the food preferences of C. elegans mutants defective in chemosensory receptors genes were analyzed. We did a binary choice assay in which animals were put on the center of the plates and were allowed to migrate towards either control or tested bacterial lawns on opposite sides of a NGM plate. In this assay, a choice index of -1.0 represents complete preference for Escherichia coli OP50, an index of 1.0 represents complete preference for the test bacteria, and an index of 0 represents an equal distribution. Our results suggested that, the odorant receptor mutants are defective in preference assay compared to C. elegans wild type. We conclude that, the odorant receptor genes are involved in the bacterial choice preference in the habitat of C. elegans.