The Raelian Movement
for those who are not afraid of the future : http://www.rael.org
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On the Trail of the Epigenetic Code: Test System on Drosophila Should
Provide the Key to Histone Function
http://www.sciencedaily.com/releases/2010/10/101011125957.htm
ScienceDaily (Oct. 11, 2010) — Test system on Drosophila should
provide the key to histone function. The genetic inherited material
DNA was long viewed as the sole bearer of hereditary information. The
function of its packaging proteins, the histones, was believed to be
exclusively structural. Additional genetic information can be stored,
however, and passed on to subsequent generations through chemical
changes in the DNA or histones.
Scientists from the Max Planck Institute for Biophysical Chemistry in
Göttingen have succeeded in creating an experimental system for
testing the function of such chemical histone modifications and their
influence on the organism. Chemical modifications to the histones may
constitute an "epigenetic histone code" that complements the genetic
code and decides whether the information from certain regions of the
DNA is used or suppressed.
The research, now available online, appears Nov. 1 in EMBO reports.
How do you get a two-metre-long DNA thread into the cell nucleus? By
winding it into a ball, of course! The DNA is wound around proteins
known as histones, becoming 50,000 times shorter as a result. Other
proteins then aggregate on it to form chromatin and, finally, the
chromosomes. The latter are the product of an ingenious packaging
trick. The five types of histones (H1, H2A, H2B, H3 und H4) fulfil
even more tasks, however, and this is what makes them so fascinating.
Histones can have small chemical attachments, such as acetyl, methyl
and phosphate groups, in different places. These cause the opening of
the chromatin, for example, and hence enable the genetic information
to be read. Conversely, certain areas of the DNA molecule can be
deactivated and rendered unreadable through other modifications, such
as the binding of proteins. Scientists refer to this process as "gene
silencing." "The histone modifications can intervene in the control of
gene activity in this way and, as a result, complement the genetic
code," explains Herbert Jäckle, Director of the Max Planck Institute
for Biophysical Chemistry in Göttingen.
Every time a cell divides, this modification pattern of the histones
is inherited by the daughter cells. The scientists assume that this
epigenetic inheritance is controlled by a cell-specific or
organ-specific "histone code." "This decides whether the cell
machinery has access to the DNA-coded genes or whether the access is
blocked," says Jäckle. The scientists would very much like to crack
this code: for the production of the histones, hundreds of gene copies
are stored in the genome of higher organisms. Therefore, up until now,
it appeared to be impossible to switch off these gene copies and
replace them with genetically-modified histone variants. Researchers
could only create a test system if they managed to do this: if these
variants lack certain docking sites, for example for chemical groups,
certain modifications to the histones could be prevented and it would
then be possible to investigate the extent to which the absence of
these modifications leads to diagnosable defects in the organism.
The Max Planck researchers in Göttingen have now succeeded in
developing a new method for researching the function of all histone
modifications. The cell biologists removed all of the histone genes
from the genome of the fruit fly Drosophila melanogaster. As a result,
the cells could no longer divide. As occurs with normal cell division,
the organism's genome is still doubled through DNA synthesis but the
cell then remains at a standstill in the division cycle and the
organism dies. The situation normalises progressively, however, with
the increasing number of copies of the four histone genes produced:
"Flies with twelve copies of the histone gene cluster ultimately
survive and are capable of reproducing," explains Jäckle's colleague
and project leader Alf Herzig.
It had already been established for multicellular organisms that
several copies of the histone gene are required for the organism to
survive. However, the results obtained by the researchers also
indicate that the cell realises during division that histones are
lacking, and the division of the cell is then halted despite the fact
that DNA has already been doubled -- as is the case during all cell
division processes. "Communication paths clearly exist between the
histone production process and the cell division machinery," says Ufuk
Günesdogan, a doctoral student in the department. Most importantly,
the researchers now have a test system at their disposal into which
histone variants can be channelled for the gradual experimental
examination of the function of histone modification and, ultimately,
the histone code in the organism. It can only be a matter of time now
until the code is finally cracked.
Editor's Note: This article is not intended to provide medical advice,
diagnosis or treatment.
Story Source:
The above story is reprinted (with editorial adaptations by
ScienceDaily staff) from materials provided by
Max-Planck-Gesellschaft.
Journal Reference:
1. Ufuk Günesdogan, Herbert Jäckle, Alf Herzig. A genetic system to
assess in vivo the functions of histones and histone modifications in
higher eukaryotes. EMBO reports, 2010; 11 (10): 772 DOI:
10.1038/embor.2010.124
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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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