Ontogeny of lower jaw movement in wildtype zebrafish larvae. (A)Tg(isl1:GFP) larvae from 3, 5, and 7 dpf were mounted in a lateral position, under a brightfield microscope, in agarose with the head free to move, and the opening of the mouth due to lower jaw movement (gape; white triangle and double arrows) was recorded and analyzed using custom software. (B,C,E) Pooled data from 3 experiments (number of larvae in parenthesis). (B) Gape frequency, increased sharply from 3 to 7 dpf, plateauing by 9 dpf. (C) Gape magnitude, a measure of the amount of jaw movement, increased sharply between 3 and 5 dpf, and plateaued thereafter. (D) There were two patterns of gape events – Distributed, with jaw movements distributed uniformly throughout the observation period, and Clustered, with tightly clustered jaw movements with intervals of inactivity. (E) The distributed gape pattern was predominant at every age examined, and there was no significant difference between 5, 7, and 9 dpf. Statistical analysis was carried out with Chi-square test and One-way analysis of variance (ANOVA) with post hoc Tukey’s HSD (honest significance difference). NS, not significant, *p < 0.05, **p < 0.01.
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