Figure 5.

Cyclic gene expression in msd∷LfngHA2 and msd∷LfngHA3 transgenic mice. (A) Endogenous Lfng expression in day 9.5 embryos detected by in situ hybridization with an intron probe. Dorsal (panels a–g,l–o,t) and lateral (panels a‘–g‘,l‘–o‘,t‘) views of the same embryos are shown. (Panels a–c) The three phases of Lfng expression in wild-type embryos. In transgenic embryos, essentially two types of patterns were observed. In one group of embryos (two examples are shown in panels d,e and l,m, respectively), there was only expression in the anterior psm either in broad domains or in stripes that were in most cases poorly defined and diffuse. In the second group of embryos (two examples are shown in panels f,g and n,o, respectively), there was a broad domain of anterior expression (white arrowheads in panels f,g,n,o), and additional expression in the posterior psm (black arrowheads in panels f,g,n,o) separated by a region of no or low expression (bars in panels f,g,n,o). (Panels h–k,p–s) Noncultured (0‘) and cultured day 9.5 embryo tail halves (culture times indicated in the lower right corners) after in situ hybridization. Lfng expression clearly changed during 60 and 90 min of culture, and similar expression patterns were observed after 120 min. Arrowheads in panels i,j,q,r point to expression domains that changed during culture. In Lfng mutant embryos (panel t) lacZ transcripts derived from the Lfng^lacZ allele, which reflect transcription of the endogenous locus, were present in a broad domain in the anterior psm and appeared down-regulated and diffuse in the posterior psm of different embryos homozygous for the Lfng^lacZ null allele. (B) Hes7 expression in day 9.5 wild-type, Dll1 mutant (panel t), msd∷LfngHA2 (panels d–g), and msd∷LfngHA3 (panels l–o) transgenic embryos. Dorsal (panels a–g,l–o,t) and lateral (panels a‘–g‘,l‘–o‘,t‘) views of the same embryos are shown. (Panels a–c) The three phases of Hes7 expression in wild-type embryos. In transgenic embryos essentially two types of patterns were observed. In one group of embryos (two examples are shown in panels d,e and l,m, respectively) there was strong expression in the posterior psm and a domain of homogenous weaker expression extending further anteriorly. In the second group of embryos (two examples are shown in panels f,g and n,o, respectively) there was a domain of strong expression in the posterior psm (black arrowheads in panels f,g,n,o) and a band of strong expression in the anterior psm (white arrowheads in panels f,g,n,o) that were separated by a variable region of weaker expression (bars in panels f,g,n,o). (Panels h–k,p–s) Noncultured (0‘) and cultured day 9.5 embryo tail halves (culture times indicated in the lower right corners) after in situ hybridization. Hes7 expression changed during 60 and 90 min of culture, whereas similar expression patterns were observed after 120 min. For example, expression was up-regulated in the posterior psm (arrowheads in panels i,q), or down-regulated in the posterior psm (arrowheads in panels j,r). In Dll1 mutant embryos (panel t) Hes7 expression was confined to the posterior psm and appeared similar in all embryos. The number of embryos with each pattern or phase and the total number of analyzed embryos is indicated for each genotype.