How to Make a Neurocrystal: Modeling the Developmental Patterning of the Fly's Eye
- Event time: 1:00pm
- Event date: 2nd May 2006
- Speaker: David Lubensky (Vrije Universiteit Amsterdam)
- Location: Room 2511, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
Animals' ability to create complex patterns is an enduring source of wonder and a topic that has long drawn the interest of scientists of all stripes. Here, we study one of the most remarkable and best-characterized examples of such pattern formation, the development of the fruit fly's compound eye. In the fly larva, a front of differentiation moves across the sheet of tissue that will become the adult retina. It leaves behind it a hexagonal array of cells marked by high levels of the protein Atonal. The basic genetic logic governing this process has to a considerable extent been deciphered in recent years [e.g. Frankfort and Mardon, 2002]. We build on these advances with the first model of retinal patterning based on experimentally verified interactions. Surprisingly, we conclude that a Turing instability of a uniform state cannot, as usually assumed, by itself produce the observed behavior. Instead, we propose that the pattern is generated primarily by a novel ''epitaxial'' process in which, as the front progresses, each newly-created row of unit cells acts as a template for the next one. A clear prediction of this model is that if the communication between successive rows is broken, even transiently, a striped pattern will appear. Preliminary experimental tests suggest that just such a phenomenon occurs in some mutants. Related patterning processes have been observed in systems as diverse as chick feather buds and vertebrate retinal ganglion cells [Pichaud, Treisman, and Desplan, 2001]; our model may thus describe a motif that has been reused many times throughout evolution.
This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..