| June
14, 2007--The
human genome sequencing begets a logical question: How are
our genetic instructions decoded by cells into biological
functions? This week’s Nature
published results from a four-year project to identify and
analyze functional elements taken from a minute fraction
of the human genome. The findings suggest our genetic
blueprint is not a simple one, but a complex network in
which genes, along with regulatory elements and other
types of DNA sequences that do not code for proteins,
interact in overlapping ways.
The Encyclopedia of DNA
Elements (ENCODE) Project is a public research consortium
launched by the National Human Genome Research Institute
in September 2003. ENCODE’s mission is to identify all
functional elements in the human genome sequence in three
phases: a pilot project phase, a technology development
phase, and a planned production phase.
For the pilot of the
ENCODE Project, 35 groups provided over 200 data sets,
comprising around 1% of the human genome. From this
strategically selected cross section, Ewan Birney (from
the European Molecular Biology Laboratory’s European
Bioinformatics Institute in Hinxton, England) and an
international consortium derived a number of exciting new
insights into both the nature and evolution of DNA
sequences important for biological function.
For
example, most of the DNA studied appears to be transcribed
into RNA, and these DNA transcripts overlap extensively.
This does not support the traditional view that the human
genome contains a relatively small set of discrete genes
alongside a vast amount of biologically inactive DNA.
The
team also found that around 50% of the genome's functional
elements appear to be able to change sequence more freely
than expected across mammalian evolution. This suggests
the existence of a large pool of neutral functional
elements that are biochemically active but provide no
specific benefit (e.g., in terms of survival or
reproduction) to the organism, which may serve as a
“warehouse” for natural selection.
Twenty-eight
companion papers appear in the June issue of Genome
Research.
Copyright
2007, Cambridge Healthtech Institute. All Rights Reserved.
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