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The Raelian Movement
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A mystery solved: How genes are selectively silenced
http://www.biologynews.net/archives/2010/10/18/a_mystery_solved_how_genes_are_selectively_silenced.html?utm_id=1000&utm_source=Newsletter&utm_medium=Email&utm_campaign=Newsletter
October 18, 2010 08:16 PM
Our genetic material is often compared to a book. However, it is not
so much like a novel to be read in one piece, but rather like a
cookbook. The cell reads only those recipes which are to be cooked at
the moment. The recipes are the genes; 'reading' in the book of the
cell means creating RNA copies of individual genes, which will then be
translated into proteins.
The cell uses highly complex, sophisticated regulatory mechanisms to
make sure that not all genes are read at the same time. Particular
gene switches need to be activated and, in addition, there are
particular chemical labels in the DNA determining which genes are
transcribed into RNA and which others will be inaccessible, i.e. where
the book literally remains closed. The biological term for this is
epigenetic gene regulation.
Among the epigenetic mechanisms which are well studied is the
silencing of genes by methyl groups. This is done by specialized
enzymes called methyltransferases which attach methyl labels to
particular 'letters' of a gene whereby access to the whole gene is
blocked. "One of the great mysteries of modern molecular biology is:
How do methyltransferases know where to attach their labels in order
to selectively inactivate an individual gene?" says Professor Ingrid
Grummt of the German Cancer Research Center (DKFZ).
Grummt has now come much closer towards unraveling this mystery. She
has focused on studying those text passages in the genetic material
which do not contain any recipes. Nevertheless, these texts are
transcribed into RNA molecules in a controlled manner. "These
so-called noncoding RNAs do not contain recipes for proteins. They are
important regulators in the cell which we are just beginning to
understand," says Ingrid Grummt.
In her most recent work, Grummt and her co-workers have shown for the
first time that epigenetic regulation and regulation by noncoding RNAs
interact. The scientists artificially introduced a noncoding RNA
molecule called pRNA into cells. As a result, methyl labels are
attached to a particular gene switch so that the genes behind it are
not read. The trick is that pRNA exactly matches (is complementary to)
the DNA sequence of this gene switch. The investigators found out that
pRNA forms a kind of plait, or triple helix, with the two DNA strands
in the area of this gene switch. Methyltransferases, in turn, are able
to specifically dock to this 'plait' and are thus directed exactly to
the place where a gene is to be blocked.
More than half of our genetic material is transcribed into noncoding
RNA. This prompts Ingrid Grummt to speculate: "It is very well
possible that there are exactly matching noncoding RNA molecules for
all genes that are temporarily silenced. This would explain how such a
large number of genes can be selectively turned on and off."
Source : Helmholtz Association of German Research Centres
"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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