Fig. 1

Segmentation defects in mutants are stochastic.

a Her1-Her1 and Her7-Hes6 dimers form a negative feedback loop by repressing their own transcription. b Somite boundaries are marked by xirp2 ISH staining in sibling her1^ci302 mutant embryos. While the upper embryo has no segmentation defect, lower embryo has 6 defective segmentation boundaries (marked by the star). Insets show 500-µm-wide enlarged images of boundaries. Scale bar is 300 µm. c, d Percentage of her1^ci302 mutants displaying wild-type phenotype (striped) or segmentation defects (dotted) at 28 °C (c, n = 50, N = 15), and number of defective boundaries per each side of her1^ci302 mutants (d, n = 100, N = 15). The violin plot shows the median (thick black line) and quartiles (thin black lines). exirp2 ISH staining of her7^hu2526 mutants. Insets show 500-µm-wide enlarged images of boundaries. Scale bar is 300 µm. f Scoring of segmentation defect position of one her7^hu2526 mutant embryo raised at 28 °C. g The Pearson correlation of same side consecutive somite phenotype (n = 222, N = 3), and (h) same position left- and right-side somite phenotype (n = 111, N = 3) between 11th and 30th somite boundaries. n is the number of embryos in (c, h), and sides in (d, g); N is the number of fish pairs in (c, d), and number of independent experiments in (g, h). Source data are provided as a Source Data file.