A cellular resolution atlas of gene expression in Drosophila pseudoobscura reveals interspecies variation in embryonic patterning.
1) Department of Systems Biology, Harvard Medical School, Boston MA.
2) Life Sciences and Genomics Division, Lawrence Berkeley National Laboratory, Berkeley, CA.
3) Computer Science Division, University of California, Berkeley, CA.
4) Department of Computer Science, University of California, Irvine, CA.
5) Institute for Data Analysis and Visualization, University of California, Davis, CA.
Understanding how transcriptional regulatory sequences evolve requires us to link changes in sequence with changes in function. We have applied high-resolution microscopy and image processing methods to blastoderm embryos of D. melanogaster and D. pseudoobscura to determine the expression patterns of key transcriptional regulators and a subset of their targets in their native context at cellular resolution in 3D over the hour prior to gastrulation. These techniques allow multiple types of statistically rigorous inter-species comparisons to be made, both between individual embryos and between composite multi-gene models, revealing widespread quantitative changes in expression patterns. We measure multiple types of variation, including changes in spatial position and number of cells comprising a pattern. These changes are gene specific; there is no overall trend in how expression patterns vary. Moreover, we see that portions of a gene expression pattern driven by distinct regulatory elements can change independently. Together these results argue that there are functional consequences of the regulatory sequence variation between D. melanogaster and D. pseudoobscura. Interpreting these functional differences in the context of specific sequence changes will shed light on cis-regulatory architecture, and the functional constraints under which cis-regulatory elements evolve.
Last modified March 27, 2008.