'Rolling Circles' Provide New Way to Amplify and ...( By drawing upon nature's own DNA...)

By drawing upon nature's own DNA-copying techniques, University of Rochester chemist Eric Kool has developed minute rings of DNA -- dubbed "rolling circles" -- that can crank out more copies of the genetic template less expensively than methods now at scientists' disposal.

A patent for the technology has been approved by the U.S. Patent Office and will issue soon. Kool has also presented the work at several scientific conferences, and has published results in the Journal of the American Chemical Society.

"This method of DNA production is very easy and inexpensive," Kool says. "You can just toss a rolling circle, some free DNA nucleotides, and DNA-copying enzymes into a test tube, and when you come back 12 hours later, the tube is full of DNA.

"It's now feasible to make bucketfuls of DNA, an amount we can't even begin to approach with other amplification techniques."

Unlike other DNA-copying techniques now in use, rolling circles don't require special enzymes or complex equipment like thermocyclers, so the method could reduce the cost of genetic research or routine laboratory testing. It might also open the door to new procedures requiring very high sensitivity -- such as detection of DNA sequences in organisms' genomes, for instance, or identification of specific cancer-related mutations.

The new method of DNA production uses as its template a single piece of circular DNA far smaller than that found in even the tiniest of organisms. Like a molecular fishing reel, this tiny ring of DNA unfurls a long strand of daughter DNA that repeats a single sequence hundreds of times. Using molecular scissors known as restriction endonucleases -- which always cut DNA strands at precisely the same array of neighboring bases -- scientists then cut this long strand of DNA into many smaller strands with sequences that exactly complement the template.

In the lab, Kool has produced strands of
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Contact: Steve Bradt
sbradt@admin.rochester.edu
716-273-4726
University of Rochester
21-Jan-1998