A Morphogenetic Framework for Analyzing Gene Expression in Drosophila Melanogaster Blastoderms.
1) Life Sciences and Genomics Division, Lawrence Berkeley National Laboratory, Berkeley, CA.
2) Computer Science Division, University of California, Berkeley, CA.
3) Institute for Data Analysis and Visualization, University of California, Davis, CA.
4) Computer Science Department, University of Kaiserslautern, Germany.
To fully understand and be able to computationally model the spatial complexity of developmental regulatory networks, it is critical to measure gene expression patterns at the resolution of individual cells. To this end, we have developed image analysis techniques for extracting 3D embryo morphology and quantifying gene expression at cellular (i.e., nuclear) resolution in Drosophila melanogaster blastoderm embryos (see also Luengo et al., Fowlkes et al., Knowles et al.). Using these methods on data from blastoderms of whole fixed embryos, we have discovered that well before gastrulation there are complex a/p and d/v nuclear density changes around the embryonic blastoderm. These changing densities correspond to nuclear movements whose directions and magnitudes we have estimated using both time-lapse images of live, histone2A-GFP embryos and pointcloud data from fixed embryos. Because the scale of nuclear movements are significant relative to the x,y,z locations of different genes' expression patterns in the embryo, our data indicate that blastoderm pattern formation needs to be analyzed in a morphodynamic, rather than a morphostatic environment. As an example, we describe the movement of eve and ftz pair-rule stripes during stage 5 and compare these to the predicted nuclear flow.
Last modified March 9, 2006.