Profiling patterned transcripts in Drosophila embryos.

Here we describe a high-throughput screen to isolate transcripts with spatially restricted patterns of expression in early embryos. Our approach utilizes robotic automation for rapid analysis of sequence-selected cDNAs in a whole-mount in situ hybridization assay. We determined the spatial distribution of a random collection of 778 different genes from an embryonic cDNA library and show that a significant fraction of these exhibit patterned profiles of expression. In addition, gene ontology studies revealed groups of gene products exhibiting shared expression patterns, providing new insights into the largely overlooked effector molecules that function in development. As described in this paper, automated hybridization to whole-mount embryos in situ proved to be straightforward and provided us with a very powerful method for the global survey of gene expression in early embryos. From the perspective of biological significance, our finding that many spatially restricted transcripts correspond to loci encoding novel transcripts that have not been previously identified in nearly saturating genetic screens for maternal effect and zygotic lethals is particularly notable.