Sean B. Carroll, PhD

Nobel Conference 50
Oct. 7 & 8, 2014

Evolutionary developmental biologist Sean B. Carroll, PhD – professor of molecular biology, genetics, and medical genetics, University of Wisconsin at Madison; investigator and vice president for science education, Howard Hughes Medical Institute

How does an early embryo establish front and back? determine where limbs or other body parts should develop? determine what the structure of those limbs will be? Beginning in the mid-1980s, Sean B. Carroll’s research has been instrumental to our understanding of the molecular genetics of animal development. Using the fruit fly, Drosophila melanogaster, as a model system, he and his colleagues have investigated developmental “patterning” genes whose expression establishes the main axes of an animal and controls the subsequent development of body parts. These genes code for proteins known as transcription factors, which regulate whether a gene is turned on or off. As more and more animal genomes have been sequenced, Carroll and others were surprised to find that genes similar to those in fruit flies control developmental decisions in most other animals, including humans, and are key to our understanding of the evolution of animal diversity.

How can similar sets of genes result in the differences in structure we see in the animal world? Carroll’s research group has focused on the “genetic switches” called enhancers that bind transcription factors to turn genes on. Specifically, they have looked at the enhancers for genes that interact with developmental transcription factors. Using fruit fly body color as one model system for investigation, they determined that the differences in color patterns between many of the species of Drosophila resulted from mutations in gene enhancers associated with the yellow gene. For example, one of the yellow gene enhancers is necessary for black pigment expression in the fly abdomen; fly species that do not contain this enhancer due to mutation will not have black pigment in their abdomens and will be yellow. Thus, the explanation for much of evolutionary change is found not in the protein-coding regions themselves, but in the non-protein coding regions that make up the vast majority of an animal’s genome.

Sean Carroll earned his BA in biology at Washington University in St. Louis (1979) and a PhD in immunology from Tufts University School of Medicine (1983). He joined the laboratory of Matthew Scott, then at the University of Colorado-Boulder, as a post-doctoral researcher. There he started his investigations of the molecular basis of Drosophila patterning with the segmentation gene fushi tarazu (ftz). Currently, Carroll is the Allan Wilson Professor of Molecular Biology and Genetics at the University of Wisconsin at Madison and a Howard Hughes Medical Institute investigator and vice president for Science Education. A member of the National Academy of Sciences and noted author, his book Remarkable Creatures: Epic Adventures in the Search for the Origins of the Species was a 2009 finalist for the National Book Award. Highly regarded for his work in science education, he was recognized with a Distinguished Service Award by the National Association of Biology Teachers in 2007.