French researchers have produced a physical map of 33,000cloned DNA fragments that constitutes 90 percent of the humangenome.

Scientists at the Centre d'Etude du Polymorphisme Humain(CEPH) and Genethon, a division of the French MuscularDystrophy Association, described the methodology and resultsof their work in this week's issues of Nature and theProceedings of the French Academy of Sciences.

Daniel Cohen, director of CEPH and co-founder of Genethon,headed an international team of 50 researchers. The map priorto this one only covered 2 percent of the human genome. Paris-based CEPH noted that the map, a continuous ordered set ofDNA fragments, and all the information generated to constructit could fill a book as high as the Eiffel Tower (1,000 feet).

This data will be made available over the international sciencecomputer network Internet progressively through the end ofDecember. In addition, a 300-page condensed report of thedata will be published in early 1994.

To produce the map, the researchers cut a set of human DNAinto pieces and transferred each piece into the DNA of a yeastcell. As the yeast cell grew and divided, it produced a clone ofthe human DNA, called a yeast artificial chromosome (YAC). TheYACs were then cut into pieces and analyzed for detection ofoverlapping sections, then pieced back together into a map ofDNA sequences. With these sequences, scientists can nowattempt to locate each of the 100,000 human genes located on23 pairs of chromosomes.

The map developed by Cohen and his colleagues will accelerategene mapping. Researchers have discovered genes by usinggene markers -- sequences of DNA that accompany a gene. If agene marker is located, researchers know the gene is nearby.With the genome map, they will be able to pick out the preciseDNA fragment containing this marker rather than lookingthrough a "haystack" of DNA fragments. CEPH said the next stepis to refine the map and develop more precise generations of it.

The French team has been working on the map for 10 yearsutilizing megaYACS, which are up to 1 million base pairs long(approximately two-and-a-half times longer than those ofnormal YACs).

They also automated the mapping process with robots thatwork up to 10 times faster than technicians. CEPH noted that20 robots can daily perform 2,400 Southern blots (one of thetechniques used to distinguish DNA fragments), a task thatwould require 200 technicians and researchers to do manuallyin the same amount of time. The robotics technology wasdeveloped by French engineering firm Labimap and AmershamLifescience.

A CEPH representative said the National Institutes of Healthand other U.S. research institutes have been working onmapping the genome for three years and are using small piecesof DNA.

The cost to develop the map was $40-50 million from 1983 to1993. NIH and the European Economic Community contributedto CEPH's funding.

To ensure that Third World countries are included in thegenome project, Cohen has created the Africa Foundation, thegoal of which is to transfer new genome technology to researchorganizations in Africa and to find treatments for diseasesaffecting the people of Africa. CEPH said one of the first diseasetargets will probably be malaria. The government of Tunisiahas donated land for the first laboratory, and a fund-raisingcampaign is now under way to generate $50 million forconstruction and the first three years of funding.

-- Brenda Sandburg News Editor

(c) 1997 American Health Consultants. All rights reserved.