July 18, 2007 --
Sequence data for both chromosomes can be inferred under the right circumstances, USC biologists say.
University of Southern California biologists have developed a method for sequencing both chromosomes of an organism.
Their study appears in a recent issue of Genome Research.
statistical method is significant because when researchers announce
they have sequenced an organism's genome, they really mean that they
have created a mosaic of two chromosomes, said USC computational
biologist Lei Li.
"A mosaic means it's not real," Li said.
author and former graduate student Jong Hyun Kim, advised by Li and USC
University Professor Michael Waterman, was able to infer a complete
sequence of the chromosomes of Ciona intestinalis, a marine
invertebrate, from existing sequencing data.
exploited the high rate of genetic mutations in the organism. Other
organisms with high genetic variability, such as certain fish, also may
Because the human genome has a relatively low mutation rate, the method cannot be applied to people.
However, Kim said, the method might be useful in sequencing parts of the human genome that display high variability.
a by-product of their analysis, the researchers added to growing
evidence that so-called junk DNA may have a function after all.
studies have shown that junk DNA expresses proteins which may regulate
gene function, and that sections of junk DNA have been highly conserved
during evolution, suggesting that they play an important role.
The Genome Research study confirms that many short sections of junk DNA are highly conserved, Li and Kim said.
Source : University of Southern California