<i>Her1</i> mutants exhibit defects in somitogenesis.

<p>Electropherogram of <i>her1</i> (A) and <i>her7</i> (B) amplicons in wild type (top), homozygous <i>her1^hu2124</i> (bottom, A) and <i>her7^hu2526</i> (bottom, B) mutant fish. Schematics above the sequences depict the exon- and intron-organization and the protein domains encoded by the exons. Point mutations are indicated by asterisks. (C, D) Brightfield pictures of wild type and <i>her1</i> mutant embryos, lateral view, anterior to left. Compared to wild type embryos (C, asterisks), the first 3 somitic borders in the <i>her1^hu2124</i> mutant appear diffuse and partly disrupted (D, bracket). In situ analysis of <i>myoD</i> expression in wild types indicates characteristic half-segmental expression within the somites (E, asterisks indicate somites 1–3). <i>myoD</i> expression is diffuse in the first 3 somites of <i>her1^hu2124</i> embryos (F, bracket). (G, H) and (K, L) show half-segmental respectively r/c polarity wild type expression pattern of <i>mespb</i> at 10–12 somite stage and between 90% epiboly and bud stage, respectively. (I, J) and (M, N) represents <i>mespb</i> expression in the <i>her1^hu2124</i> mutant at 10–12 somite stage and between 90% epiboly and bud stage, respectively. Expression of <i>mespb</i> is disturbed in the <i>her1^hu2124</i> mutant between 90% epiboly and bud stage (M, N), when the anlagen of the first somites are pre-patterned. Compared to one or two stripes in the wild-type (K, L), <i>mespb</i> is expressed in a salt and pattern (M, N). <i>mespb</i> expression is unperturbed at 10–12 somite stage in <i>her1^hu2124</i> mutants (I, J). Dorsal views, anterior to top.