Fig 2. Hunchback directly represses eve3+7.

(A) Predicted Hb binding sites in wild-type and mutant versions of eve3+7 are depicted as vertical bars along the sequence where height is proportional to PATSER score [68]. Hb sites are indicated in blue; other regulators are in grey. (B) 2D projections of atlas data for reporter constructs expressed in wild-type or sna::hb embryos. Data is taken from timepoint 4. (C) 2D projection of a representative wild-type embryo expressing eve3+7 lacZ. We plot gene expression as a function of anterior-posterior (AP) position by averaging measurements from lateral strips in individual embryos and normalizing them to their maximum value (see E). (D) 2D projection of a representative sna::hb embryo expressing eve3+7 lacZ. To quantify the effect of ventral Hb in individual embryos, we take average measurements from lateral strips, extract the local maxima corresponding to stripes 3 and 7, and subtract those values from the corresponding peaks of the ventral strip. We perform the same analysis in wild-type embryos to account for modulation along the DV axis. A decrease in the ventral/lateral difference between wild-type and sna::hb embryos indicates Hb repression, while an increase indicates Hb activation (see F). (E) Lateral line traces from individual wild-type embryos containing eve3+7 reporter constructs (eve3+7: grey, n = 26; eve3+7mutHb: blue, n = 9). Embryos are from all six timepoints in stage 5. (F) Differences between ventral and lateral stripe peaks are plotted for individual wild-type and sna::hb embryos in all 6 timepoints in stage 5. Top: wild-type eve3+7 (wt: n = 26; sna::hb: n = 19); Bottom: eve3+7mutHb (wt: n = 9; sna::hb: n = 13). Asterisks indicate significant differences between wild-type and sna::hb embryos (p-value < 0.001, Mann-Whitney U test). Differences between wild-type and sna::hb embryos containing eve3+7mutHb were not significant (p-value > 0.4 for both stripes, Mann-Whitney U test).