Fig. 6. Hes7 transcription is affected in Lfng^FCE1/FCE1 embryos. (A) Hes7 expression in 8.5 dpc embryos, using a probe specific for intronic sequences. In wild-type embryos, several distinct patterns of expression are seen with a Hes7 intron probe (a-c, n=20), reflecting cyclic Hes7 transcription. In Lfng^FCE1/FCE1 (d, n=6) or Lfng^-/- (e, n=4) embryos, Hes7 mRNA is transcribed ubiquitously throughout the PSM, suggesting that, at this stage, Lfng activity is required for Hes7 oscillation. (B) Hes7 expression, as detected with a probe specific for intronic sequences in 10.5 dpc embryos. At 10.5 dpc, Hes7 mRNA expression levels and transcription oscillate in wild-type (a-c, n=13/51 phase 1, 18/51 phase 2, 20/51 phase 3), Lfng^FCE1/FCE1 (d-f, n=13/32 phase 1, 8/32 phase 2, 11/32 phase 3) and Lfng^-/- (g-i, n=10/22 phase 1, 5/22 phase 2, 7/22 phase 3) embryos. (C) Hes7 RNA expression was examined using a cDNA probe that reveals the steady-state levels of mature Hes7 mRNA. In wild-type 8.5 dpc embryos, several distinct patterns of expression are seen (a-c, n=9), while in Lfng^FCE1/FCE1 (d, n=7) embryos, Hes7 mRNA is found ubiquitously throughout the PSM. At 10.5 dpc, oscillatory expression is seen in both wild-type (e, n=11; f, n=9) and Lfng^FCE1/FCE1 (g, n=8, h, n=9) embryos. (D) 10.5 dpc embryos were bisected along the neural tube, and one half was fixed (a,c,e), while the other half was cultured for 1 hour prior to fixation (b,d,f). The Hes7 expression pattern is altered between the fixed and cultured halves of wild-type (a,b), Lfng^FCE1/FCE1 (c,d) and Lfng^-/- (e,f) embryos, confirming that Hes7 RNA levels can oscillate in the absence of LFNG activity.