FIGURE 3.

The 4-ketone moiety is the key structural feature for C. elegans detection of CAI-1. a, chemotaxis indices for carbon chain length variants of CAI-1 and homoserine lactone AIs at 100 μm. Values are the mean ± S.D. of triplicate assays from three independent experiments. Unequal two-tailed t tests were performed comparing data for each CAI-1 variants and each homoserine lactone molecule to the CAI-1 bar. *, p < 0.05; **, p < 0.01. b, structures corresponding to a. c, chemotaxis indices for compounds with varied positioning of the hydroxyl and/or ketone group of CAI-1. d, structures corresponding to compounds in c. In panels b and d, the stereochemistry of each molecule is depicted. See “Experimental Procedures” for details.