Mice appear to thrive without junk DNA

Mice -- and perhaps humans -- can thrive when large amounts of so-called junk DNA are deleted from their genome, according to results of experiments reported in the October 21 issue of Nature.

"It was an architectural approach. If you want to question whether a wall is weight-bearing you remove it and see if the ceiling falls in," said Edward Rubin, director of the US Department of Energy Joint Genome Institute (JGI).

The mouse genome was published nearly two years ago. Mice and humans share 99 per cent of their genes, as well as sequences of junk DNA that have no known function.

Researchers from JGI and the Lawrence Berkeley National Laboratory in California compared the mouse and human genomes and identified regions to delete. They did so in mice embryonic stem cells and generated a strain of mice with the abridged genome, then analysed features such as growth, longevity and molecular and biochemical features.

"By and large, these deletions were tolerated and didn't result in any noticeable changes," said Marcelo Nobrega, who collaborated on the research.

"An important caveat, however, is that no matter how detailed our analyses, our ability to test for a particular characteristic in mice is limited," he added in a statement.

Identifying disposable DNA sequences may narrow the search for genetic causes of disease.

"As far as disease goes, these are probably regions where there may be functions but they are subtle at the best," said Rubin.