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 What happens in the cell nucleus after fertilization
06.12.2016 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Simple processing technique could cut cost of organic PV and wearable electronics

06.12.2016 | Materials Sciences

3-D printed kidney phantoms aid nuclear medicine dosing calibration

06.12.2016 | Medical Engineering

Robot on demand: Mobile machining of aircraft components with high precision

06.12.2016 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>