Housekeeping gene expression during development, as measured by QPCR. Embryos were collected at timed intervals (2, 6, 12, 24, 48, 72, 96, and 120 hpf) and pooled (50 embryos/pool, 3 pools per time point) for analysis. Ct values represent mean +/- SEM from three biological replicates. Note that the y-axis differs in the three panels to show gene groups based on Ct range during development: (top to bottom) highly expressed genes (bactin1, elfa, 18s), genes with highly variable expression (tuba1, gapdh), g enes with moderate expression (tbp, b2m, g6pd). All genes showed significant differences across developmental stages by one-way ANOVA p < .05.