Chapter 18, Problem 5P

Consider the even $-$ skipped regulatory sequences in Figure $18.9$.

a. How are the sharp boundaries of expression of eve stripe $2$ formed?

b. Consider the binding sites for gap proteins and Bicoid in the stripe $2$ enhancer module. What sites are occupied in parasegments $\text{2, 3, and 4}$, and how does this result in expression or no expression?

c. Explain what you expect to see happen to even-skipped stripe $2$ if it is expressed in a Krüppel mutant background. A hunchback mutant background? A giant mutant background? A bicoid mutant background?

Figure 18.9