Essential Genetics 6th Edition by Daniel Hartl

Exercise 20

Edward B. Lewis, Christianne Nüsslein-Volhard, and Eric Wieschaus shared a 1995 Nobel Prize in physiology or medicine for their work on the developmental genetics of Drosophila. In their screen for developmental genes, Nüsslein- Volhard and Wieschaus initially identified 20 lines bearing maternal-effect mutations that produced embryos lacking anterior structures but having the posterior structures duplicated. When Nüsslein-Volhard mentioned this result to a colleague, the colleague was astounded to learn that mutations in 20 genes could give rise to this phenotype. Explain why his surprise was completely unfounded.