Chapter 18, Problem 6P

This problem concerns a technique called enhancer trapping which scientists first developed in Drosophila. The purpose is to find enhancers in the genome and thereby to identify genes that are active in particular cell types. In enhancer trapping, thousands of fly lines are created, each of which has a single copy of the transgene shown here integrated into a random location in the genome via P element–mediated gene transfer. Note that the transgene has a promoter but no enhancer. (The thick horizontal arrows indicate the inverted repeats at the ends of P elements.)

 

a.	How could you identify fly lines in which the transgene integrated next to an enhancer?
b.	Describe how you could use this technique to identify genes expressed specifically in the fly wing.
c.	Do you think that homozygotes for any of the transgene insertions might have a mutant phenotype? Explain.