Scientists have identified and placed in exact order all of the 97 million genetic code that spell out the instructions for making a tiny, soil-dwelling worm, providing the first complete genetic blueprint of any animal and promising new insight into human development and disease.
Caenorhabditis elegans,a one millimeter long shiny translucent roundworm lives in soil and eats bacteria. It would take 25 of them lined up from end to end to measure one inch long. C. elegans only has 20,000 genes and 97 million DNA units. In contrast, humans have 80,000 genes and 3 billion DNA units. Laboratory study and scientists have focused on this tiny worm because it has most of the basic characteristics of complex animals yet is simple enough to understand.
Worms, like humans, have a nervous system, eats, grows, engages in sex, ages and dies. After almost a decade of work, British and American researchers have for the first time constructed a step-by-step guide showing how to grow a nervous system, reproductive system, digestive tract and other body parts, work.
Scientist know every step of the wormsí development from embryo to an adult creature that has 959 cells. They know all of the 302 neurons that compose the wormís nervous system and the exact spot where each neuron branches out and connects to every other. They also know an enormous amount about the wormís basic biology and behavior, including how it responds to touch, temperature and odor. With all of the wormís 19,900 genes precisely mapped and spelled out on the creatureís six pairs of chromosomes, at last researchers have a fully described living system that can be used as a model for understanding other organisms, including humans.
So far 70 percent of the thousands of human genes identified can be found in identical or similar genes in the worm- indicating that nature tends to use and reuse whatever materials that work. Scientists state that these similarities mean that worm genes will vastly improve understanding of human embryo development, aging, and innumerable ailments such as Alzheimerís disease and cancer.
Harold Varmus, director of the National Institutes of Health, which funded the work stated, "The unveiling of this genome gives us the first real picture of what itís like to be a multicellular, complex organism such as ourselves." Until now, only simple organisms have had their genetic codes completely spelled out, including a few viruses, bacteria and a single-celled yeast.
The gene sequencing work was led by Robert Waterston of Washington University in St. Louis and John Sulston of the Sanger Centre in Cambridge, England.
Adapted from The Sacramento Bee. 1998. December 11. Pages A1, A26. Scientists untangle wormís genetic code. Rick Weiss, Washington Post.