Pufferfish helps sort out 'junk' DNA

WASHINGTON -- Sequencing the genes of the pufferfish is yielding clues to the more complex human genetic makeup.

While pufferfish, or fugu, is a delicacy in Japan, it has interested scientists because it has the smallest genome of any vertebrate.

In sequencing its genome, researchers at the Joint Genome Institute in Walnut Creek, Calif., discovered that the pufferfish has about the same number of genes as humans, but without most of the repetitive so-called "junk" DNA that fills out the human genome.

That helps scientists identify genes that are obscured by the repetitive sequences in the human genome, researchers said.

By comparing the human and pufferfish genomes, the researchers said they have been able to predict the existence of about 1,000 human genes that had not been previously identified.

The functions of these hypothetical genes are not yet known, but being able to sort them out from the junk DNA is a step to determining what they do, the researchers said.

Dr. Samuel Aparicio of Cambridge University in England noted that when the puffer and human genomes were compared, researchers found 961 cases where there was a match in the human that didn't overlap an already predicted or known gene.