Timing Embryo Segmentation: Dynamics and Regulatory Mechanisms of the Vertebrate Segmentation Clock

Table 3

Perturbations of the somitogenesis molecular clock achieved in mouse, chick, or zebrafish embryos. When mentioned, alterations in clock periodic oscillations, somite formation, and wavefront gene expression are indicated.

	Perturbation	Clock	Somite	Wavefront	Reference
Mouse	⊣Wnt	↑period	n.d.	n.d.	[89]
		Δlfng, hes7, axin2
	nrarp mutant	↑period			[90]
		(95 min)	↓number (1)	✓ fgf8
		↻ hes5, hes7, lfng
	⊣Notch	↓period			[90]
	↓hes7 introns	↓period	↑number (1)	n.d.	[91]
		(115 min)
			↑number (1-2)	n.d.
			↓length
Chick	⊣Wnt	↑period	↓number (1)	n.d.	[89]
		(115–120 min)	✓length
		Δlfng, axin2
	⊣Shh	↑period (~3 h)	↓number (2-3)	↓fgf8	[92]
		Δlfng, hairy2	✓length	↑raldh2
Zebrafish	delta ligands mutants	↑period	↓number (1)	n.d.	[93]
			↑length

↑: increased; ↓: decreased; ↻: normal oscillations; Δ: altered oscillations; ✓: normal expression; n.d.: not done.