Activation of SiHsTRPA and AmHsTRPA by saturated medium-chain fatty acids. Activation of SiHsTRPA and AmHsTRPA by saturated fatty acids was analyzed by calcium imaging. The mean value of fold change of Fura-2 ratio with error bar (± SEM) is shown for the fatty acid (propionic acid, C3; butyric acid, C4; valeric acid, C5; heptanoic acid, C6; hexanoic acid, C7; octanoic acid, C8; nonanoic acid, C9; decanoic acid, C10; undecanoic acid, C11; and lauric acid, C12) stimulated DsRed-positive (blue) and DsRed-negative (yellow) cells. The total numbers of SiHsTRPA- and AmHsTRPA-transfected cells analyzed were 97–212 and 61–157, respectively. **, Significant difference by one-tailed Welch’s t test (P < 0.001). The traces in extended data Figs. 4-1 and 4-2 indicate the changes of intracellular calcium level in SiHsTRPA- and AmHsTRPA-expressing cells by above fatty acids, respectively.