The variation represents a previously unrecognized level of genomic organization and complexity, the scientists report, one that may exist in all cells with nuclei.
Made in yeast, the discovery offers broad potential uses, said Dr. Jason D. Lieb, a University of North Carolina at Chapel Hill biologist and a report author.
"For example, in pathology laboratories, differences in chromatin shape and structure in mammalian cells are routinely determined by staining tissues and observing them under a microscope," said Lieb, also a Carolina Center for the Genome Sciences researcher. "This is an important assay used to identify specific cell types and malignancies. It is possible that a detailed genomic view of these variations, provided by the method we describe in our paper, could be used to diagnose and sub-type cancer and other diseases."
It also could be an important tool for assigning functions to subsections of the genome, particularly for finding active genes, which remains a difficult problem, he said.
The report will appear online this week and in the May 27 issue of the Proceedings of the National Academy of Sciences. Other authors, all at Stanford University, are Drs. Peter L. Nagy and Michael L. Cleary of pathology and Dr. Patrick O. Brown of biochemistry.
"If the DNA from a single human chromosome were stretched and measured end-to-end, it would extend to over half an inch in length," Lieb said. "Our cells are much, much smaller than that, of course, and in order to fit inside the cell's nucleus, which is even smaller, DNA must be compacted about 1,000-fold relative to i
Contact: David Williamson
University of North Carolina at Chapel Hill