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Central dogma of genetics maybe not so central
In thousands of genes, RNA is not a faithful copy of DNA
http://www.sciencenews.org/view/generic/id/65063/title/Central_dogma_of_genetics_maybe_not_so_central
By Tina Hesman Saey
Thursday, November 4th, 2010
WASHINGTON — Text messagers and computer gamers aren't alone in the
willful misspelling department. RNA molecules do it too.
RNA molecules aren't always faithful reproductions of the genetic
instructions contained within DNA, a new study shows. The finding
seems to violate a tenet of genetics so fundamental that scientists
call it the central dogma: DNA letters encode information and RNA is
made in DNA's likeness. The RNA then serves as a template to build
proteins.
But a study of RNA in white blood cells from 27 different people shows
that, on average, each person has nearly 4,000 genes in which the RNA
copies contain misspellings not found in DNA.
"It's unbelievable," says Mingyao Li, a geneticist at the University
of Pennsylvania Medical School in Philadelphia. Li presented the
finding November 3 in Washington, D.C., at the annual meeting of the
American Society of Human Genetics.
Scientists already knew that every now and then RNA letters can be
chemically modified or edited — sort of the molecular equivalent of
adding an umlaut to some letters. But those RNA editing events are not
common.
What Li and her colleagues discovered is quite common. RNA molecules
contained misspellings at 20,000 different places in the genome, with
about 10,000 different misspellings occurring in two or more of the
people studied. The most common of the 12 different types of
misspellings was when an A in the DNA was changed to G in the RNA.
That change accounted for about a third of the misspellings.
Some researchers who saw Li's presentation asked whether a virus used
in growing the white blood cells that the researchers studied might be
the source of the shenanigans. Li and her collaborators had wondered
the same thing. In order to rule out the virus, the researchers
analyzed skin cells from the same people and found that RNA
misspellings originally discovered in the white blood cells were also
in the skin cells. And the misspellings aren't just rare, random
mistakes. "When DNA and RNA differ from each other it happens in
nearly every RNA" copy, Li says.
The researchers don't yet know how the RNA misspellings happen. They
could be substitutions made while the RNA copy is being made, or the
changes could happen later. The consequences of the misspellings are
also unknown. For instance, misspellings might cause the RNA to be
degraded faster or interfere with the molecule's ability to make
proteins.
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"Ethics" is simply a last-gasp attempt by deist conservatives and
orthodox dogmatics to keep humanity in ignorance and obscurantism,
through the well tried fermentation of fear, the fear of science and
new technologies.
There is nothing glorious about what our ancestors call history,
it is simply a succession of mistakes, intolerances and violations.
On the contrary, let us embrace Science and the new technologies
unfettered, for it is these which will liberate mankind from the
myth of god, and free us from our age old fears, from disease,
death and the sweat of labour.
Rael
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