April 27, 2009
A six-year effort by an international consortium of researchers has resulted in the genome sequence of the domestic cow. Published in the journal Science, this is the first full genome sequence of any ruminant (4-chambered stomach) species. Using a Hereford cow as the DNA source, they found that the cattle genome contains a minimum of 22,000 genes. The researchers note that the cow genome is more similar to that of humans than to the genomes of mice or rats, but appears to have undergone significant reorganization, perhaps due to domestication. Mooving immediately to milk the sequence information, a second article in the same issue used thousands of variations in the sequence at a single DNA base (called single nucleotide-polymorphisms or SNPs) to characterize the genetic diversity among different cattle breeds. The information offers udderly significant opportunities for cattle breeders to select for features that they want. Dr. Harris A. Lewin of the University of Illinois at Urbana-Champaign notes in an accompanying commentary that “The barnyard door is now open. We can expect that any animal with medically or agriculturally useful traits will be sequenced and resequenced.” Researchers will no doubt be rushing to steak their claims.