Fig. 1

Gain of SLO-2 function decelerates transition of preference in thermotaxis behavior. a A scheme for a thermotaxis assay is shown. C. elegans cultivated at a certain temperature is placed at the center of a linear thermal gradient without food and is allowed to freely migrate for 1 h. b A neural circuit regulating thermotaxis is shown. c, d Wild-type (c) and slo-2(nj131gf) (d) animals were cultivated at 17 °C for 5 days and then at 23 °C for the time indicated or constantly at 23 °C for 3 days. The animals were then placed on a thermal gradient. The number of animals in each section of the thermal gradient was determined, and the proportion of animals in each region was plotted on a histogram. n = 6, 10, 6, 6, 6, 6, 3 for each time point (c, d). The error bars represent the standard error of mean (SEM). e The thermotaxis indices at each time point (c, d) were plotted against time after the cultivation temperature was changed to 23 °C. Horizontal bars indicate medians. **p < 0.01, ***p < 0.001 (Welch two-sample t test). f The thermotaxis indices are shown for animals cultivated constantly at 23 °C in c, d. g Genomic PCR fragments covering slo-2 gene locus that were derived from either wild-type or nj131 mutant animals were injected into either wild-type or nj131 animals. Animals were cultivated at 17 °C for 5 days and at 23 °C for 3 h and then subjected to thermotaxis assay, as described above. Animals with extra chromosomal arrays were scored to evaluate thermotaxis. The fractions of animals were plotted on histograms (upper), and the thermotaxis indices were shown on boxplots (lower). n = 24, 5, 14, 14, 9 for each strain. The indices of strains marked with distinct alphabets differ significantly (p < 0.001) according to Tukey–Kramer test. h, i Wild-type and indicated slo-2 mutant animals were cultivated at 17 °C for 5 days and at 23 °C for 3 h and then subjected to thermotaxis assay. n = 4 or 5. p Values are indicated (Dunnett test against wild-type (h) or Tukey–Kramer test (i)). See also Supplementary Fig. 1