Nematode Makes Scientific History
St. Paul, MN (June 1, 1999) ñ For the first time in history, scientists now have the complete blueprint of the genetic information that makes an animal. British and American scientists, headed by Dr. John Sulston and Dr. Bob Waterston respectively, announced in the 1998 December 11th issue of Science that they completed the sequencing of the whole genome of the tiny soil-dwelling, free-living nematode Caenorhabditis elegans. This landmark biological accomplishment is described on the American Phytopathological SocietyÃs feature home page this month at www.scisoc.org, which highlights the implications for plant nematology in sequencing C. elegans and contains links to related sites.
"For plant nematologists, this accomplishment represents the beginning of an exciting new chapter in efforts to understand plant-associated nematodes," says Joseph Esnard, a nematologist at Cornell University and member of the American Phytopathological Society and Society of Nematologists. "The sequence provides plant nematologists with a supermarket of nematode genes to shop from."
The completion of sequencing the C. elegans genome is also significant from the point of view that it is the first complete sequence of a multicellular organism. Yeast was the first organism with an organized nucleus to have its genome completely sequenced, but it is single-celled.
Caenorhabditis elegans is a hermaphroditic, non-segmented roundworm-like animal with skin, muscles, and alimentary, nervous, excretory, and reproductive systems. It contains 959 cells, of which neurons make up a third. The C. elegans sequencing consortium estimated the genome size to be approximately 97 million DNA base pairs (on six chromosome pairs) that encode more than 19,000 genes.
Plant nematologists have concentrated their research efforts on plant parasitic nematodes, which are obligate parasites, requiring a host to complete their life cycles. Though C. elegans is not a plant parasite, it is thought to have many of the "same" genes as plant parasitic nematodes. Scientists who worked on the C. elegans genome project claim that 40% of the nematode genes are essentially the same as in humans.
"This revelation bodes well for plant nematologists studying ëparasitism-relatedà genes in much closer relatives," says Esnard. "The availability of the genome sequence will facilitate molecular cloning of plant parasitic nematode genes by using primers that match nematode sequences of interest. These are exciting times for plant molecular nematologists because, if gene order is highly conserved, simply sequencing regions adjacent to conserved genes will open up treasures. . . and thatÃs just the beginning."
Fabio Piano, a developmental biologist at Cornell University, agrees and adds that new techniques such as RNA interference, which is the inhibition of gene function through RNA injections, could pave the way to functional analyses in many other nematode species. "In turn, these analyses can be geared toward the discovery of essential nematode genes which can be used as targets for nematode control," Piano says.
For more information on C. elegans, visit the APS June web feature story at www.scisoc.org with photographs and links to additional sites. The American Phytopathological Society (APS) is a professional scientific organization dedicated to the study and control of plant disease with 5,000 members worldwide.
###
RSS