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Scientists crack genetic code of lowly worm

A microscopic view of Caenorhabditis elegans, a humble nematode worm less than one millimeter (1,000 microns) long.   

December 11, 1998
Web posted at: 3:10 PM EST

(CNN) -- A tiny worm is in the center of a history-making event. Scientists announced Thursday that they have completed the first complete genetic blueprint of a multi-celled animal.

The worm, called Caenorhabditis elegans, is only about as big as the head of a pin. It lives in the dirt and eats even more lowly bacteria like the ubiquitous E. coli. But it has long been a favorite of researchers studying animal biology.

"We have before us all the pieces of the puzzle that it takes to make a worm," Robert Waterston of Washington University in St. Louis, who led the U.S. contribution to the effort, told a news conference. "Now we need to figure out how it works," he added wryly.

"This is a watershed event in the history of biology," Dr. Harold Varmus, director of the National Institutes of Health, which helped fund the project along with Britain's Medical research Council, said. "It is the first complete blueprint of a complex organism."

It took researchers at Washington University and the Sanger Center in Cambridge, England, eight years to break the DNA code of C. elegans' nearly 20,000 genes. At least 40 percent of them match genes found in other animals, the researchers said.

And although worms are very different from people, studying the genes of C. elegans will help scientists understand human beings.

"What's in a worm is in a person and we can use worms to analyze human genes -- where they are, how they work and how they go wrong," said Robert Horvitz, a worm and human genetics expert at the Massachusetts Institute of Technology.

Although it is tiny, the threadlike nematode has much in common with more complex species, said Waterston.

"It's got muscles. It reacts to touch," he said. "It faces the same challenges other animals do." Genes involved in cancer, immune diseases, even AIDS, are found in C. elegans.

"The genes that it takes to make a nerve cell are very well represented in C. elegans," Waterston said. "The same is true for muscle."

Scientists decoded more than 100 million chemical sequences that make up the worm's DNA code. The similarities between worm and human genes will also help scientists understand human disease.

Francis Collins of the National Institutes of Health says that gives new confidence to medical researchers and patients. "The hopes of the parent of a child with a birth defect, the hopes of a young man with a family history of cancer, the hopes of a couple caring for an aging parent are in some way advanced by our having this instruction book of an animal which is a model for all of those circumstances."

Waterston says, thanks to the worm, they have been able to isolate a gene suspected to cause Alzheimer's disease in humans. "They have similar genes in the worm and the only reason we really know about what those genes do in people is because they've been studied in worms."

Teams around the world are examining the genomes -- the complete collection of genetic information including the genes -- of a variety of creatures, from bacteria to people.

The smaller the creature, the easier it is to "sequence" its genes. So far, only one-celled creatures such as viruses, yeast and several bacteria have been sequenced.

C. elegans, which is found in huge numbers in the soil in temperate regions, is the biggest creature to be completed. It can cast enormous light on human genetics, the researchers said, acting as a kind of Rosetta stone to help decode the information held in DNA.

Scientists say they have sequenced about 6 percent of the human genes so far. Since humans contain 30 times more DNA than C. elegans, a complete genetic fingerprint for humans will not be complete until the 2003.

Correspondent Ann Kellan and Reuters contributed to this story.

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