Thirty years after the discovery of the transcriptional enhancers that drive patterned gene expression in animal embryos, we still do not really understand how they work. One mystery is why it is that there are potential transcription factor binding sites everywhere, but only a small fraction of the genome functions as enhancers. I will talk about recent work in our lab that suggests that the conventional explanation for this phenomenon - that enhancers are found where binding sites are organized in a specific manner - does not explain available data, and instead that, in the early fly embryo at least, there are parallel systems involving different sets of factors and processes that determine where enhancers are located and what patterns they encode.

Michael Eisen is a Professor of Genetics, Genomics and Development at University of California, Berkeley and an Investigator of the Howard Hughes Medical Institute. He works primarily on flies, and his research encompasses evolution, development, genetics, genomics, chemical ecology and behavior. Eisen is interested in understanding how the spatial and temporal patterns of gene expression that choreograph development are established in the early Drosophila embryo and in characterizing the ways that microorganisms manipulate the behavior of animals, including humans.