The researchers also examined the organization and structure of chromatin in the cells throughout the life stages of each organism. Chromatin is the protein superstructure that packages DNA and modulates which sections of the genome are accessible to regulatory molecules that convert the genetic code into cellular action. Both groups discovered specific chromatin signatures associated with the regulation of protein-coding genes. Unique chromatin signatures were associated with distinct regions of the genome that either turn genes on or off.
"Chromatin signatures are emerging as a powerful lens into the structure and function of the regulatory portion of the genome that controls cell activity," said Manolis Kellis, Ph.D., senior author of the fruit fly paper and associate professor of computer science, Massachusetts Institute of Technology, Cambridge.
Next, to identify sites responsible for controlling when genes are turned on during the development of an organism, and in which tissues genes are used, the researchers searched across the genomes of worm and fly during key developmental stages. Primarily, they looked for transcription factors regulatory proteins often found in specific tissues that control the expression of different genes. In both organisms, they found that many different regulatory proteins bind to the same, overlapping regions of the genome in both organisms, which they call highly occupied targets (HOT).
"Networks give one a different view of the genome than a linear parts list and potentially provide a way of connecting together many chromosome elements to give us insights into how the genome functions," said Mark Gerstein, Ph.D., first author of the roundworm paper an
|Contact: Geoff Spencer|
NIH/National Human Genome Research Institute