The discovery? Bring back a once-important but now rarely used molecular technique and combine it with newer cloning and DNA sequencing methods. The effect is a dramatic leap in efficiency.

"It can reduce the cost of sequencing entire genomes by 50 to 95 percent," said Andrew Paterson, director of the UGA Plant Genome Mapping Laboratory (www.plantgenome.uga.edu) and a professor of crop and soil sciences, botany and genetics.

That kind of savings could be staggering. Sequencing the sorghum genome, used as an example to develop the new Cot-based Cloning and Sequencing (CBCS) method, would cost about $7.5 million, compared to $20 million with the current "shotgun" approach.

The difference is in the number of clones required to be sequenced. Sequencing the onion genome would require 119 million clones. CBCS slashes that to 15 million, eliminating the immense time and $354 million in funding required to do the other 104 million. For the sugar pine, CBCS cuts 281 million required clones to 60 million, knocking down costs by $750 million.

The thing that drives up the time and cost to sequence a genome is its vast number of relatively meaningless DNA sequences. "Repetitive sequences complicate all aspects of gene and genome research," Paterson said.

These highly repetitive sequences are, in essence, genetic junk, said Daniel Peterson, research coordinator with the Plant Genome Mapping Lab. There may be thousands, even millions, of copies of a single sequence. One such sequence, for example, is repeated nearly a million times in the human genome, accounting for nearly 10 percent of human DNA.

"Most of these are ancient viruses," Peterson said. "They're 'selfi
'"/>

Contact: Kim Carlyle
kosborne@uga.edu
709-583-0913
University of Georgia
6-May-2002