Wavelength-dependent effects on behavioural light aversion.

<p>(<b>A</b>) Mice entrained to an LD12:12 cycle were exposed to 405 nm (violet), 470 nm (blue), and 530 nm (green) light at ZT14 in a light/dark box for 10 min. (<b>B</b>) In the first 1 min of the test, mice spent significantly more time in the hidden zone under blue light compared to violet, green, or control (dark) conditions. One-way repeated measures ANOVA for light condition, F_(3.25) = 20.696, <i>p</i> ≤ 0.001. Post hoc Tukey dark versus violet <i>p</i> = 0.006, dark versus blue <i>p</i> = 0.021, dark versus green <i>p</i> ≤ 0.001, blue versus violet <i>p</i> ≤ 0.001, blue versus green <i>p</i> ≤ 0.001. (<b>C</b>) In the following 9 min, mice exposed to blue light continued to spend more time in the hidden zone compared to violet or green light. One-way repeated measures ANOVA light condition over time 2–-10 mins, F_(3,25) = 11.721, <i>p</i> ≤ 0.001. Post hoc Tukey dark versus violet <i>p</i> = 0.635, dark versus blue <i>p</i> = 0.021, dark versus green <i>p</i> = 0.635, violet versus blue <i>p</i> ≤ 0.001, blue versus green <i>p</i> ≤ 0.001. (<b>D</b>) <i>Opn4</i>^<i>-/-</i> mice (open bars) showed different responses to both blue and green light. In the first minute of the test, in comparison with wildtype mice, <i>Opn4</i>^<i>-/-</i> mice spent less time in the hidden zone in response to blue light. However, <i>Opn4</i>^<i>-/-</i> animals spent more time in the hidden zone compared with wildtype under green light. Two-way repeated measures ANOVA for light condition and genotype, light condition x genotype interaction F_(1,26) = 20.585, <i>p</i> ≤ 0.001. Post hoc Tukey wildtype versus <i>Opn4</i>^<i>-/-</i> blue <i>p</i> = 0.010, green <i>p</i> = 0.001. (<b>E</b>) Whilst the attenuated response to blue light in <i>Opn4</i>^<i>-/-</i> mice persisted over the remaining time course of the test (one-way repeated measures ANOVA for effect of genotype over time, F_(1.13) = 14.376, <i>p</i> = 0.002), no difference was observed between wildtype and <i>Opn4</i>^<i>-/-</i> mice under green light (one-way repeated measures ANOVA for effect of genotype over time, F_(1.13) = 0.26, <i>p</i> = 0.617). <i>Opn4</i>^<i>-/-</i> mice showed no statistical difference in responses to wavelength in the first minute or whole time of the test (one-way repeated measures ANOVA for effect time over wavelength F_(9,81) = 0.976 <i>p</i> = 0.466). Histograms reflect mean percentage ± SEM of time spent in the dark box of the light dark box during the 10 min trial (<i>n</i> = 6–-10/group wildtype, <i>n</i> = 4–-10 <i>Opn4</i>^<i>-/-</i>). Significant differences indicated by *** <i>p</i> ≤ 0.001, ** <i>p</i> ≤ 0.01, * <i>p</i> ≤ 0.05, NS = not significant. The data used to make this figure can be found in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002482#pbio.1002482.s003" target="_blank">S3 Data</a>.