Evolution or
Creation?
DNA
more complex than first thought, study finds
Research
may speed up process of treatment and prevention
-
Rick Weiss, The Washington Post (June
2007)
The
first concerted effort to understand all the inner workings of the DNA molecule
is overturning a host of long-held assumptions about the nature of genes and their
role in human health . . . scientists reported last week.
The
new perspective reveals DNA to be not just a string of biological code but a dauntingly
complex operating system that processes many more kinds of information than previously
appreciated. The findings, from a project involving hundreds of scientists in
11 countries and detailed in 29 papers published last week, confirm growing suspicions
that the stretches of "junk DNA" flanking hardworking genes are not
junk at all.
But
the study goes further, indicating for the first time that the vast majority of
the 3 billion "letters" of the human genetic code are busily toiling
at an array of previously invisible tasks. The new work also overturns the conventional
notion that genes are discrete packets of information arranged like beads on a
thread of DNA.
Instead,
many genes overlap one another and share stretches of molecular code. As with
phone lines that carry many voices at once, that arrangement has prompted . .
. complex switching, splicing and silencing mechanisms – mostly located between
genes – to sort out the interwoven messages.
The
new picture of the inner workings of DNA probably will require some rethinking
in the search for genetic patterns that dispose people to diseases such as diabetes,
cancer and heart disease, the scientists said, but ultimately the findings are
likely to speed the development of ways to prevent and treat a variety of illnesses.
One
implication is that many, and perhaps most, genetic diseases come from errors
in the DNA between genes rather than within the genes, which have been the focus
of molecular medicine.
Complicating
the picture, it turns out that genes and the DNA sequences that regulate their
activity are often far apart along the 6-foot-long strands of DNA intricately
packaged inside each cell.
How
they communicate is still largely a mystery.
Altogether,
the new project shows that the simple sequence of DNA letters revealed to great
fanfare by the $3 billion Human Genome Project in 2003 was but a skeletal version
of the human construction manual. It is the alphabet, but not much more, for a
syntactically complicated language of life that scientists are just now beginning
to learn.
"There's
a lot more going on than we thought," said Dr. Francis Collins, director
of the National Human Genome Research Institutes of Health that financed most
of the $42 million project.
The findings come from the Encyclopedia of DNA Elements project, nicknamed Encode. While much of the decades-long effort to understand DNA's role in health and disease has been driven by scientists' interest in particular genes, Encode focused on a representative 1 percent of the genome. Using a variety of experimental and computational approaches, the researchers sought to catalogue everything going on there.