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| Heidelberg, 6 March 2007 |
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| An architectural plan of the cell
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![The electron tomogram of a complete yeast cell reveals the cellular architecture. It shows plasma membrane, microtubules and light vacuoles [green], nucleus, dark vacuoles and dark vesicles [gold], mitochondria and large dark vesicles [blue] and light vesicles [pink].](press06mar07_s.jpg) |
The electron tomogram of a complete yeast cell reveals the cellular
architecture. It shows plasma membrane, microtubules and light vacuoles
[green], nucleus, dark vacuoles and dark vesicles [gold], mitochondria and
large dark vesicles [blue] and light vesicles [pink].
Picture by Johanna Höög, EMBL |
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Scientists produce the first high resolution 3D image of a complete eukaryotic cell
Press
Release 6 March 2007 [PDF]
Downloadable picture [2 MB]
Swedish
Like our body every cell has a skeleton
that provides it with a shape, confers rigidity and protects its
fragile inner workings. The cytoskeleton is built of long protein
filaments that assemble into networks whose overall architecture
and fine detail can only be revealed with high resolution electron
microscopy images. Researchers at the European Molecular
Biology Laboratory [EMBL] and the University of Colorado have
now obtained the first 3D visualisation of a complete eukaryotic
cell at a resolution high enough to resolve the cytoskeleton's precise
architectural plan in fission yeast. The image of this unicellular
organism will be published in this week's issue of the journal
Developmental Cell and reveals remarkable insights into the fine
structure of the cytoskeleton as well as its interactions with other
parts of the cell.
A key component of the cytoskeleton are long, tube-like filaments
called microtubules. They are dynamic structures built of constantly
growing and shrinking rows of elementary proteins called
tubulins. To increase their rigidity, microtubules associate in bundles
and interact with stabilizing proteins in complex networks,
which are essential for many cellular processes such as polar
growth.
"To really understand the architecture of the cytoskeleton you
have to see the entire cell in three dimensions," says Claude
Antony, whose team carried out the research at EMBL, "but at the
same time you need a very good resolution to be able to investigate
its structural details. It is impossible to obtain such detailed
images of a eukaryotic cell with normal microscopes."
To bridge the gap between global overview and structural detail
Antony's team collaborated with yeast and electron microscopy
expert Richard McIntosh at the University of Colorado. Using a
technique called electron tomography, Johanna Höög, PhD student
Antony's lab, took pictures of sequential sections of a yeast
cell from many different angles through an electron microscope
and combined these snapshots into a 3D reconstruction on the
computer. A similar principle is used to generate brain scans.
For the first time they could see directly what previous studies in
fission yeast only suggested. In times when a cell is not dividing, a
microtubule bundle consists of 4-5 individual filaments that are
physically connected with each other via minute bridges likely
formed by proteins. In the networks created through this
crosslinking the orientation of microtubules is crucial. The filaments
are polar structures, their two ends grow and shrink at different
rates. The study created a precise map indicating the location
of all growing and shrinking microtubule ends in the cell.
The images also shed light on other important functions of
microtubules, revealing that the cytoskeleton determines the correct
positioning of mitochondria, the energy-producing
organelles, throughout the cell.
"Our 3D image of fission yeast can serve as a reference map of the
cell for all biologists interested in its architecture," says Johanna
Höög. "You can extract information about all sorts of cellular
structures and processes from it or use it to place findings into the
spatial context of the cell."
Yeast is one of the most commonly used model organisms in biology.
It has many similarities with higher eukaryotes, including
multicellular organisms. Many of the insights gained into its cellular
organisation are likely to apply also to mammals. In mammalian
nerve cells, for example, microtubule bundles similar to
those observed in yeast are essential for the transmission of the
signal from cell to cell.
Source Article
J.L. Höög, C. Schwartz, A.T. Noon, E.T. O'Toole, D.N. Mastronarde, J.R. McIntosh & C. Antony. Organization of interphase microtubules
in fission yeast analyzed by electron tomography, Developmental Cell, 6 March 2007
Press Contact
Anna-Lynn Wegener
Press Officer
EMBL Heidelberg
Tel: +49 6221 387-8452
Email: wegener@embl.de |
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![The electron tomogram of a complete yeast cell reveals the cellular architecture. It shows plasma membrane, microtubules and light vacuoles [green], nucleus, dark vacuoles and dark vesicles [gold], mitochondria and large dark vesicles [blue] and light vesicles [pink].](press06mar07_l.jpg)