Genetic control of early structural development
Edward B. Lewis, Christiane Nusslein-Volhard and Eric F. Wieschaus fly (Drosophila) embryos.
In the late 1970s much was known about the various stages of embryonic development, but the control of these stages was poorly understood. Christianne Nusslein-Volhard and Eric F. Wieschaus wanted to find the genes that cause a fertilised egg to transform into a segmented embryo. Each embryo segment goes on to form specific parts of the offspring’s body, so this is a vital stage in early embryo formation.
Nusslein-Volhard and Wieschaus conducted their work in fruit fly embryos because of their rapid development. They randomly mutated fruit fly genes and monitored the effects. After a year of this work, the pair had identified 15 genes that when mutated, affected the segmentation of fruit fly embryos. By analysing the results of mutations, the researchers were able to determine the function of each gene and when it is most important; for instance, some genes affected the definition of an embryo’s head and tail ends, while others took action later in development, affecting specific segments.
Edward B. Lewis also studied fruit flies. He was interested in the mutation that caused fruit flies to develop two sets of wings, instead of their usual one. In the late 1970s he discovered the HOX gene complex, which controls the development of embryonic segments into different parts of the body, and whose malfunction was responsible for the fruit flies with too many wings.
It has since been shown that very similar genes to those identified by Lewis, Nusslein-Volhard and Wieschaus perform the same functions in other animals, including humans. Mutations in these genes are now known to cause many of the congenital malformations affecting humans.