The effect of Rosovitine on mPSM explants: a real time analysis

Previously we showed, using fixed tissue techniques, that treatment of chick embryos with a family of pharmacological inhibitors yields increased levels of NICD, an increased NICD half life and longer segments (Wiederman et al., 2015). Here we measure the effect of one of the pharmacological perturbations (Roscovtine) using a real time reporter of the somitogenesis clock. After processing the reporter signal using empirical mode decomposition, we measure the oscillator period in mPSM explants and find, in agreement with the previous study, that the period of the segmentation clock increases upon Roscovitine treatment. However, we also make the novel discovery that the differentiation rate of the mPSM tissue also increases upon Roscovitine treatment. Returning to the previous study, we find that the measured increases in somite size and oscillator period are only consistent with the clock and wavefront model if the wavefront velocity also increased.