for National Geographic News
Researchers have finished mapping the genome of the domestic dog.
The results show among other things that dogs, mice, and humans share a core set of DNA.
A rough sequencing of a poodle's genome was reported in 2003, but it covered only about 75 percent of the genes.
This time, "we have sequenced 99 percent of the genome of a female boxer," said Kerstin Lindblad-Toh, a geneticist at the Broad Institute of Harvard University and MIT in Cambridge, Massachusetts. She is the lead author of the dog-gene study, which appears tomorrow in the journal Nature.
The researchers also examined DNA from ten different dog breeds to spot genetic differences between them.
The comparison could help scientists find the genetic roots of dog behavior and physiology andperhaps most importantlyhelp them identify genes that cause diseases in both dogs and humans.
Dogs, Mice, and Humans
The researchers obtained the gene data from Tasha, a female boxer picked from a selection of dogs made available by breeding clubs and veterinary schools.
The geneticists sequenced the 2.4 billion "letters" of the dog's DNA code, representing 39 chromosome pairs. Humans by comparison have 23 chromosome pairs.
"The boxer genome sequence is big step towards the goal of having a complete reference sequence for a dog genome," said Ewen Kirkness, a molecular biologist at the Institute for Genomic Research in Rockville, Maryland, who led the 2003 poodle study and co-authored the new study.
Scientists had previously found that about 5 percent of the human genome sequence appears in the mouse genome. The new study shows that 5 percent of the human genome is also shared with dogs.
Significantly, the sequences that are conserved in all three species are virtually the same.
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