An architectural plan of the cell

Mar 06, 2007
Fission Yeast Cell
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). Credit: Johanna Höög, EMBL Heidelberg

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 visualization 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 in 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: European Molecular Biology Laboratory

Explore further: How do our muscles work? Scientists reveal important new insights into muscle protein

add to favorites email to friend print save as pdf

Related Stories

Rare new species of plant: Stachys caroliniana

29 minutes ago

The exclusive club of explorers who have discovered a rare new species of life isn't restricted to globetrotters traveling to remote locations like the Amazon rainforests, Madagascar or the woodlands of the ...

New terahertz device could strengthen security

33 minutes ago

We are all familiar with the hassles that accompany air travel. We shuffle through long lines, remove our shoes, and carry liquids in regulation-sized tubes. And even after all the effort, we still wonder if these procedures ...

European space plane set for February launch

42 minutes ago

Europe's first-ever "space plane" will be launched on February 11 next year, rocket firm Arianespace said Friday after a three-month delay to fine-tune the mission flight plan.

Space station rarity: Two women on long-term crew

43 minutes ago

For the 21st-century spacewoman, gender is a subject often best ignored. After years of training for their first space mission, the last thing Samantha Cristoforetti and Elana Serova want to dwell on is the ...

Recommended for you

Genomes of malaria-carrying mosquitoes sequenced

11 hours ago

Nora Besansky, O'Hara Professor of Biological Sciences at the University of Notre Dame and a member of the University's Eck Institute for Global Health, has led an international team of scientists in sequencing ...

Bitter food but good medicine from cucumber genetics

11 hours ago

High-tech genomics and traditional Chinese medicine come together as researchers identify the genes responsible for the intense bitter taste of wild cucumbers. Taming this bitterness made cucumber, pumpkin ...

New button mushroom varieties need better protection

15 hours ago

A working group has recently been formed to work on a better protection of button mushroom varieties. It's activities are firstly directed to generate consensus among the spawn/breeding companies to consider ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.