Patterning and morphogenesis of the insect head - origin of epicranial sutures and Tc-homeobrain
Developmental Neurobiology
Final Report Abstract
One of the first crucial steps of animal development is to distinguish the anterior versus the posterior pole of the embryo, i.e., the AP axis. If this process fails, embryos may develop two mirror image tails or heads. In the fly Drosophila, the mother provides the signals required for AP axis formation, while in vertebrates, gene activity of the embryo is required as well. We identified two genes whose knockdown leads to double-tail phenotypes in the beetle Tribolium, representing the insect-typical short-germ embryogenesis. Intriguingly, embryo polarity depends on zygotic gene activities and Wnt signaling. Hence, short-germ insect axis formation is more similar to vertebrates than the mechanism employed by Drosophila. Unexpectedly, the gene germ-cell less is required at the posterior pole of the fly embryo for the specification of germ-cells. In the beetle, however, the respective gene is active at the anterior pole for ensuring proper axis formation. This shows how evolution uses the same genes to perform very different actions at different locations. Further, we found different functions of the same gene in two different strains of the same beetle species. Apparently, there is ongoing evolution of this process and our finding will allow us to identify the exact nature of the differences of the system. This means that we might be able to see, how evolution actually changes the function of genes.
Publications
- Double abdomen in a short-germ insect: Zygotic control of axis formation revealed in the beetle Tribolium castaneum. Proc Natl Acad Sci USA. 2018;115:1819–24
Ansari S, Troelenberg N, Dao VA, Richter T, Bucher G, Klingler M
(See online at https://doi.org/10.1073/pnas.1716512115)
