Chemotactic behavior of mutants of the nematode Caenorhabditis elegans that are defective in their attraction to NaCl

Wild‐type C. elegans and 16 derivative strains previously selected for defective attraction to NaCl and shown to carry single‐gene mutations were tested for their responses to nine chemical stimuli to which the wild‐type responds. These were the attractants Na+, Cl−, OH−, cyclic AMP, CO2 in borate buffer, and pyridine and the repellents D‐tryptophan, CO2 in phosphate buffer, and acid. All together 563 measurements were performed. Most strains were defective in most responses but responded normally to some chemical stimuli. In a few cases mutant strains avoided a chemical that attracted the wild‐type. Analysis of the patterns of defective responses among these mutants indicates that there are probably at least four different receptors. If results previously reported are included, the minimum number of receptors is increased to six. These mutations appear to have rather discrete effects on behavior.