GENOMES may be able to shed their flab, say Ken Shirasu and his colleagues at
the John Innes Centre in Norwich, Norfolk.
As much as 70 per cent of the DNA in some organisms consists of repetitive
sequences created by 鈥渏umping genes鈥� or retrotransposons鈥攑arasitic bits of
DNA that can copy themselves. Many crops have genomes that are particularly
bloated and 鈥渙bese鈥�. Shirasu, however, discovered that the genome of barley
contains leftover fragments of retrotransposons called single long terminal
repeats, which suggests that large sections of repetitive DNA have been cut
out.
This isn鈥檛 a random process, Shirasu suggests in the latest issue of
Genome Research. Instead he thinks the barley is somehow able to control the
size of its genome, perhaps in response to the environment.
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