Gene researchers close in on nicotine's 'evil cousin'

November 15, 2002

Nicotine isn't all bad, despite its addictive qualities and its presence in tobacco products, increasingly taboo in these health-conscious times. As a chemical compound, nicotine even has beneficial properties. It's used around the world as a relatively cheap, environmentally friendly insecticide, repelling bugs that attack tobacco and other plants, and - contrary to popular misconceptions - it is not a carcinogen.

Take a nicotine molecule and snip off a methyl group, though, and you've got nicotine's evil cousin: nornicotine. (A methyl group is one carbon and three hydrogen atoms.) This truncated version of nicotine, helped by certain tobacco-leaf microbes, converts to nitrosamines - potent carcinogens - during the tobacco-curing process. If researchers could find the genetic location of the enzyme that removes nicotine's methyl group, tobacco with little or no nornicotine would be possible.

That's the task of Dr. Ralph Dewey, professor of crop science in the College of Agriculture and Life Sciences at North Carolina State University. Working with select lines of Burley tobacco, he and his colleagues are trying to isolate the nicotine N-demethylase gene from among the 25,000 or so unique genes found in tobacco.

When they're successful, says Dewey, they'll have achieved several key goals. "One, we'll have created a large genomic database. Two, we'll have the tools needed to reduce the levels of harmful nitrosamines in Burley tobacco. And three, we'll develop information that could, perhaps, lead to alternate uses for this important North Carolina crop."

Tobacco's genome, however, is just now being investigated, so Dewey and fellow researchers at the Genome Research Laboratory on NC State's Centennial Campus are faced with a painstaking process of elimination. They do have a few clues, though. Nicotine changes to nornicotine when tobacco is "senescing" - getting old and turning yellow - so genes involved in the aging process are getting a close look. They also suspect that the chromosomal location of the culprit gene is "unstable," or prone to transposition or mutation, so such locations also warrant an interested eye. And if they can verify that the gene is of the type known as a "P450," they'll have narrowed their search to about 500 genes - which is progress in Dewey's line of work.

Dewey also has access to the Genome Research Lab's microarray technology, which automates and computerizes a process once done by hand. Capable of placing up to 5,000 genes on microscope slides and showing results on a high-resolution scanner, the high-tech tool is speeding the search for the unwelcome, nornicotine-triggering gene.
-end-
Funded in part by the Philip Morris Companies, Dewey's research is a modest but important part of the larger Tobacco Genome Project ongoing at NC State's Genome Research Lab. Recognizing the huge role that tobacco plays in North Carolina's - and other states' - economy, and the need to both reduce its toxic compounds and find more uses for the crop, Dewey and his colleagues methodically pursue their quarry in the daunting molecular realm. Their efforts are largely unheralded, and success - so far - is elusive. But the days of nornicotine, nicotine's ominous cousin, are probably numbered.

Additional Media Contact:
Paul K. Mueller, News Services, 919/515-3470


North Carolina State University

Related Genome Articles from Brightsurf:

Genome evolution goes digital
Dr. Alan Herbert from InsideOutBio describes ground-breaking research in a paper published online by Royal Society Open Science.

Breakthrough in genome visualization
Kadir Dede and Dr. Enno Ohlebusch at Ulm University in Germany have devised a method for constructing pan-genome subgraphs at different granularities without having to wait hours and days on end for the software to process the entire genome.

Sturgeon genome sequenced
Sturgeons lived on earth already 300 million years ago and yet their external appearance seems to have undergone very little change.

A sea monster's genome
The giant squid is an elusive giant, but its secrets are about to be revealed.

Deciphering the walnut genome
New research could provide a major boost to the state's growing $1.6 billion walnut industry by making it easier to breed walnut trees better equipped to combat the soil-borne pathogens that now plague many of California's 4,800 growers.

Illuminating the genome
Development of a new molecular visualisation method, RNA-guided endonuclease -- in situ labelling (RGEN-ISL) for the CRISPR/Cas9-mediated labelling of genomic sequences in nuclei and chromosomes.

A genome under influence
References form the basis of our comprehension of the world: they enable us to measure the height of our children or the efficiency of a drug.

How a virus destabilizes the genome
New insights into how Kaposi's sarcoma-associated herpesvirus (KSHV) induces genome instability and promotes cell proliferation could lead to the development of novel antiviral therapies for KSHV-associated cancers, according to a study published Sept.

Better genome editing
Reich Group researchers develop a more efficient and precise method of in-cell genome editing.

Unlocking the genome
A team led by Prof. Stein Aerts (VIB-KU Leuven) uncovers how access to relevant DNA regions is orchestrated in epithelial cells.

Read More: Genome News and Genome Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.