We study the genetic basis for animal diversity, with a focus on the evolution of developmental processes ("Evo-Devo") in arthropods. Some of our work uses well studied laboratory models like the fruit fly Drosophila melanogaster and the beetle Tribolium castaneum, but we also work with animals that are much less well studied, but which, because of their position in the tree of life, are particularly important for our understanding of arthropod evolution. These include an onychophoran (the velvet worm Euperipatoides kanangrensis) and a myriapod (the centipede Strigamia maritima). For these little studied animals, we find ourselves providing some of the first modern descriptions of development. Particular areas of interest are the mechanisms that pattern the very early embryo, the different ways that arthropods generate their body segments, and the role of Hox genes in the generation of diverse body plans.
We are co-ordinators of a genome sequencing and annotation project for Strigamia maritima, in collaboration with the Human Genome sequencing Center at Baylor, and members of Evonet , a Marie Curie training network focussed on the evolution of gene regulatory networks.
The Laboratory for Development and Evolution welcomes independent research fellows with distinct but related interests in the field of "Evo-Devo". Contact Michael Akam for further information
How to turn a wing into a haltere - Hox gene targets during metamorphosis
Hox genes are the master regulators that cause different parts of the body to develop into different structures – for example, into mouthparts on the head, but legs on the thorax. It is still not known how Hox genes bring about these complex changes. In work published recently in the Proceedings of the National Academy of Sciences (USA), we have shown that the set of downstream targets regulated by one Hox gene changes dramatically as development proceeds.
We have studied the Hox gene Ultrabithorax, (Ubx for short) in fruit flies. In all insects, Ubx is active in the hind wings to make them different from the forewings. In flies, this difference is dramatic – the hind wings develop as small round balancing organs called halteres, while the forewings forms the large flat wing blades used for flying. We have engineered a system that allows us to activate the Ubx gene in developing wing blades, where it would not normally be expressed. If activated throughout development, this causes the wing blades to develop as reduced balloon-like structures resembling halteres, (see picture above). However, we can also turn Ubx on at precisely controlled times during development, and then measure its effects in the wing with assays that monitor the activity of thousands of other genes in the genome (microarray profiling and quantitative RT-PCR).
We find that the spectrum of genes regulated by Ubx changes dramatically as the animal proceeds through metamorphosis, from larva to pupa to developing adult. This explains, at least in part, how just one gene can orchestrate such complex changes in the shape and size of an organ.