Worm's turn to aid human gene project

IT MAY be only a worm but to scientists it is a milestone in understanding the genetic causes of human cancer and ageing. Scientists have for the first time unravelled the entire genetic blueprint of an animal, a nematode, 1mm long and consisting of fewer than 1,000 cells.

Sequencing the genetic code of Caenorhabditis elegans, one of the simplest known multicellular organisms, is a landmark in the quest to unravel the genetic make-up of humans.

Comparing the worm and human sequences enables scientists to identify common genes. They can use the worm to examine their function and to draw conclusions about the genetic causes of human disorders. The entire genetic code of the nematode contains 100 million letters and took an international team of scientists two decades and pounds 15m to unravel. "It's all there; all the information to `read' a worm is in this sequence and we've got it," said John Sulston, director of the Sanger Centre in Cambridge, which spearheaded the British end of the project.

C elegans is important for medical researchers because it has tissue and organs similar to humans such as a gut, nerves, muscles and skin, Dr Sulston said. "It is a microcosm of humanity. Now we have a better understanding of how an animal is built we can get some way closer to knowing how the human body works."

A joint research team, funded by Britain's Medical Research Council and America's National Institutes of Health, publish details of the research today in the journal Science. The full sequence will be available on the Internet.

The scientists estimate the nematode has 20,000 genes, compared with the 80,000 to 100,000 that make up the human genome. About 40 per cent of the nematode's genes are closely related to those found in humans, said Jonathan Hodgkin, from the council's laboratory of molecular biology in Cambridge. An area of interest is how nematode genes carry out controlled cell death, a phenomenon common to all multicellular animals and which goes awry in cancer.

"If we could control cell death in a tumour we'd have a wonderful way of controlling the growth of the tumour and preventing death," Dr Hodgkin said.

The nematode, which grows from one cell to 1,000 in three days, is also helping scientists to understand the forces behind human ageing. "It is something you can study very easily in the worm because the animal only lives for two weeks," Dr Hodgkin said. Genes controlling ageing in C elegans have been isolated and are being studied to locate and understand similar genes that influence human ageing.