How do you build a segmented body?
A central question in biology is how complex forms have evolved. One of the most widespread forms of complexity among animals is the repetition of parts, like body segments. A body plan composed of segments is found in several animal groups, annelids (think of earthworms), arthropods, and vertebrates. Arthropods, the group that includes such familiar animals as insects, crabs and spiders, are the most diverse phylum on earth.
How is their segmented body plan built in the embryo? We know that vertebrates use a segmentation clock – a system of oscillating gene expression – that produces spatially repeated segments. Recently, a segmentation clock has been demonstrated in arthropods. How does the arthropod segmentation clock work? How does the embryo elongate to add segments in the posterior? What features of those processes have been modified during evolution?
Our lab is working on these questions collaboratively with the Nagy lab at University of Arizona. In the flour beetle Tribolium, we demonstrated that the rate of segment addition varies as the embryo ad
ds it segments. What controls that change of rate? We also found that cells create highly elongated clones, associated with this change of rate. What kinds of cell movement account for this? Can we identify genes that are critical to controlling cell movements during segment addition?
The National Science Foundation, Division of Integrative and Organismal Systems and the Division of Molecular and Cellular Biosciences, has recently awarded our collaboration two grants to pursue these 
questions.