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| Modern Genetic Analysis Chapter 14. Regulation of Gene Transcription Transcription: Gene Regulation in Eukaryotes an Overview Figure 14-25. Use of a reporter-gene construct in Drosophila to identify enhancers. The top line represents a part of a plasmid, bracketed by P-element ends so that the material in between can be inserted into the genome by P-element transformation (see Chapter 13). A region of DNA thought to contain one or more enhancers is inserted immediately adjacent to a "weak" promoterthat is, a promoter that by itself cannot initiate transcription. The promoter is joined to the E. coli lacZ structural gene (the reporter gene), which encodes b -galactosidase. If there are any enhancers in the construct, they will induce tissue-specific expression of lacZ. W+ is the wild-type allele of the Drosophila white gene, used to detect the presence of the reporter-gene construct in the fly. The embryos and imaginal disks in Figures 14-26 and 14-27 are examples of expression from reporter-gene constructs in Drosophila and in mice.

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