The current theory of eukaryotic gene expression suggests that each individual gene is under the control of its own promoter sequence. In the launch issue of
Spellman and Rubin collected gene expression profiles under 88 different experimental conditions from a total of 267 GeneChip Drosophila Genome Arrays, which had been used to examine a number of experimental conditions in adult and embryonic fruit flies. After mapping the profile for each gene to the gene's chromosomal position they observed that about 20% of the genes occurred in physically adjacent groups that shared strikingly similar expression patterns.
Along the entire genome they identified ...
