Figure 1.

Figure 1.

Locomotor activity in zebrafish larvae is enhanced in the presence of AITC. A1, Protocol for the experiments presented in A2, A3. The duration of time of swimming-like tail movements and the number of tail flicks were measured in semi-restrained zebrafish (5–6 dpf) in the presence of AITC (30-s duration) or control solution (E3). During the pretest, given 1.5 min before application of AITC/E3, the response of the larva to application of E3 alone was measured. A2, Change in the duration of tail movements in response to AITC/E3. A one-way ANOVA indicated that AITC significantly enhanced locomotion as measured by the duration of movements (F_(3,40) = 27.11; p < 0.001). Tukey’s HSD post hoc tests indicated that fish treated with 10 μm (n = 11) or 100 μm (n = 11) AITC showed significantly more activity compared with fish that received either 0 μm (n = 11) or 1 μm (n = 11) AITC (p < 0.05 for each comparison). A3, Change in the number of tail flicks in response to AITC/E3. A one-way ANOVA indicated that AITC significantly increased the number of tail flicks produced by larvae (F_(3,40) = 7.85; p = 0.0003). Tukey’s HSD post hoc tests indicated that fish treated with 10 μm AITC exhibited significantly more tail flicks than fish treated with either 0 or 1 μm AITC. Note that the results presented in A2, A3 are based on the same data. B1, Experimental protocol for assessing the effect of development on AITC-induced alterations in locomotion. B2, Change in duration of tail movements in response to AITC (10 μm, 30-s duration) in larvae of different ages. A two-way ANOVA examining the effect of developmental age and exposure to AITC revealed a significant interaction (F_(2,44) = 3.54; p = 0.04) for change in duration of tail movements. For zebrafish at all developmental ages (AITC_{RESTRAINED (R)}: 3 dpf, n = 8; 5 dpf, n = 7; 12 dpf, n = 9; E3_R: 3 dpf, n = 9; 5 dpf, n = 9; 12 dpf n = 8) there was a main effect of enhanced locomotor response in response to 10 μm AITC (F_(1,44) = 77.82; p < 0.001). In addition, Tukey’s HSD post hoc tests indicated that the 12-dpf group exhibited tail movements for significantly longer after exposure to AITC than did the 3-dpf group (p < 0.05). B3, Effect of AITC (10 μm) on tail flicks in zebrafish larvae of different ages. There was a significant main effect of exposure to the chemical irritant (F_(1,44) = 46.09; p < 0.001). The interaction between AITC treatment and larval age was not significant (F_(2,44) = 0.60; p = 0.55). (The results presented in B2, B3 are based on the same data.) C1, Protocol for measuring the effect of AITC on locomotion in freely moving zebrafish larvae (5 dpf). C2, AITC (10 μm, 30-s duration) produced an increase in distance moved (AITC_{UNRESTRAINED (UR)} group, n = 12) compared with larvae exposed to control solution (E3_UR group, n = 12), as indicated by an unpaired t test (t₍₂₂₎ = 2.20; p = 0.04). This figure shows means ± SEM; in addition, * indicates a significant (p < 0.05) difference between groups and # indicates a significant (p < 0.05) main effect.