Molecular Biology Of The Cell 6th Edition by Bruce Alberts, Alexander Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter Walter

Exercise 11

4 The segmentation of somites in vertebrate embryos is thought to depend on oscillations in the expression of the Hes7 gene. Mathematical modeling explains these oscilla- tions in terms of the delays in production of the unstable Hes7 protein, which acts as a transcription regulator to shut off its own expression. Once Hes7 decays, with a half- life of about 20 minutes, its transcription resumes. To test this model, you decide to reduce the total delay by remov- ing one, two, or all three of the introns from the Hes7 gene in mice. Why do you expect that intron removal would reduce the delay? What would you predict would happen to the oscillation time, and somite formation, if the model were correct?