Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nerve cells’ power plants caught in a traffic jam

04.08.2005


Nerve cells need lots of energy to work properly, and the energy needs to be delivered to the right place at the right time. By inducing a mutation in fruit flies, researchers have figured out that a particular gene governs the movement of cells’ energy-producing units, called mitochondria.


This image shows a neuromuscular junction, where a nerve cell connects to a muscle cell and delivers a signal to the muscle. The blue-and-black striped background is the muscle cell and the green dots are the neuron’s power plants, or mitochondria. The mitochondria move within the nerve cell along the pathways called microtubules, shown here in red. Photo credit: (c) 2005 Greg Macleod & Konrad Zinsmaier.



Rather than moving to the ends of the cells, or synapses, where cell-to-cell communication takes place, mitochondria in mutant fruit flies just piled up in the center of the cell. Even so, the mutant cells could still transmit signals, although not as well.

The findings are surprising because scientists had thought any disruption in normal mitochondrial behavior would be lethal in the embryo stage. Instead, the mutant fruit fly larvae survive for five days, although they don’t live to adulthood.


"Everyone believed that mitochondria are essential at synapses -- and this is wrong," said Konrad E. Zinsmaier, the University of Arizona associate professor of neuroscience who led the research team. "The mutation allows us to study what mitochondria are really good for." The finding provides scientists with additional insight into how nerve cells work and provides a basis for understanding how such dysfunctions cause neurodegenerative diseases.

The researchers will publish their findings in the August 4 issue of the journal Neuron. A complete list of authors and their affiliations can be found at the end of this release.

Little is known about what causes mitochondria to become dysfunctional and how they contribute to neurological disorders. To learn more about what could go wrong with the energy units, Zinsmaier and his colleagues induced a mutation in the fruit fly mitochondrial protein, dMiro. dMiro stands for Drosophila mitochondrial Rho-like GTPase.

Molecular motors shuttle mitochondria within cells along cellular highways called microtubules. Normally, the mitochondria travel the length of the neuron until they reach the synapse. The mutation in the dMiro protein disabled the motor, disrupting the normal pattern of mitochondrial distribution.

The nerves’ synapses are where one nerve cell connects and communicates with other cells. For example, muscle cells contract when they receive the proper signals from nerve cells. Abnormal mitochondrial distribution within a neuron alters its ability to signal properly to adjoining muscle or nerve cells.

Instead of cruising smoothly along the microtubules, the mitochondria in mutant cells become caught in a traffic jam at the entrance ramp, located in the cell’s center.

Even though the synapses of the mutants are entirely devoid of mitochondria, the neuronal function remained intact at low levels of stimulation. But at high levels of stimulation, the mutated nerve cells failed.

Zinsmaier is now questioning the purpose of the mitochondria at the synapse. "How important are mitochondria?" he said. "We were surprised at how long the system could survive without them." Zinsmaier explained that there may be a compensatory mechanism in place that is able to deal with minor mitochondrial dysfunction within the nerve.

Besides providing energy, mitochondria carry out other tasks important for cell survival. One important mitochondrial task is taking up excess calcium. Calcium is the main ingredient for proper neuron function. Too much calcium can lead to cell death. Zinsmaier hypothesizes that there could be a specialized communication system established within neurons involving another cell component that cooperates with mitochondria to properly store calcium.

While he has begun to piece together several theories, Zinsmaier explained that it remains unclear exactly how the compensation occurs. "The real surprise is that there are mechanisms in place that can manage the system somehow," he said. "We didn’t know about them."

The findings made by Zinsmaier and his colleagues have significant implications for neurobiologists, who may now begin looking more closely at defects in mitochondrial transport. Alterations in this process may help explain how and why human neurological diseases, such as muscular dystrophy and spastic paraplegia, develop.

Mari N. Jensen | EurekAlert!
Further information:
http://www.arizona.edu

More articles from Life Sciences:

nachricht Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>