Worms reveal intron insights Team finds "newborn"
introns by comparing C. elegans and C. briggsae genomes
By Nicole Johnston
Irish researchers have discovered 122 novel introns that
appeared in the genomes of Caenorhabditis elegans and
Caenorhabditis briggsae since the two species diverged 80 to
120 million years ago, shedding light on how new introns
arise and are subsequently spread among genes.
The genomes of both worms contain roughly 100,000 introns,
of which more than 6000 are unique to one species or the
other. Kenneth Wolfe and Avril Coghlan identified 81 new
introns in C. elegans and 41 new introns in C. briggsae. Of
these, 13 are found in genes implicated in premRNA
processing, the authors report in the June 28 PNAS early
online edition.
"We used BLAST [Basic Local Alignment Search Tool] to
identify orthologous genes across all the species (animal
and nematode), and by comparison of all genes, we were
able to find intron sites present in one of the nematodes,
but absent in all other species," Wolfe, from Trinity
College Dublin, told The Scientist. "We therefore inferred
that these gained introns must be less than 100 million
years old."
Their results represent two major findings, said John
Logsdon, an evolutionary biologist at the University of
Iowa. One of these is the finding that introns are
changing a lot, both in terms of gain and loss. "The more
incredibly novel part, is that this is some of the first
evidence of how one intron can give rise to another," he
said. Even more significant is the fact that the authors
used actual sequence data to infer the process by which
introns were gained, rather than relying on phylogenetic
arguments, the conventional approach to studying intron
evolution, he added.
Read the rest at TheScientist.com
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