Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Birth of a neuron: Imaging technique tracks nervous systemgrowth and repair, Cornell-Harvard group reports

12.06.2003


A biomedical-imaging technique that would highlight the cytoskeletal infrastructure of nerve cells and map the nervous system as it develops and struggles to repair itself has been proposed by biophysics researchers at Cornell and Harvard universities.

Reporting in Proceedings of the National Academy of Sciences (PNAS June 10, 2003) , the researchers say that besides the new imaging technique’s obvious applications in studying the dynamics of nervous system development, it could answer the puzzle about which errant pathways initiate damage to brain cells, a key question about the onset of Alzheimer’s disease.

The PNAS report, "Uniform polarity microtubule assemblies imaged in native brain tissue by second harmonic generation microscopy," is the work of Watt W. Webb, professor of applied physics at Cornell and leader of the research program. His laboratory collaborators in the School of Applied and Engineering Physics are graduate students Daniel A. Dombeck and Harshad D. Vishwasrao and research associate Karl A. Kasischke, M.D. Martin Ingelsson and Bradley T. Hyman of Massachusetts General Hospital, the largest teaching hospital of Harvard Medical School, also are collaborators.



In developing nerve cells, microtubules are the pioneering extensions from the cell body that grow to form two kinds of processes: the dendrites (branches that collect and conduct impulses inward to the cell body) and the axon (the single, longer process that conducts impulses away from the neuron cell body). Microtubules, made of tiny polymers, are a major part of the cellular cytoskeleton and are responsible for mechanical support. The proposed imaging procedure capitalizes on a structural polarity that exists in the polymers, making the characteristics at one end different from the other.

The researchers predict that their system to image microtubule polarity deep within living brain tissue could expedite the study of neuronal development and repair, the dynamics of migrating cells and neurodegenerative disease.

"Never before has there been a satisfactory way of detecting polarity in microtubule assemblies in living brain tissue," says Webb. "Now we can follow the development of microtubules in vivo to see how architectural changes are occurring in nerve cells or in any other living cells where microtubules are found."

Dombeck says that changes in microtubule polarity are the key to how neurons grow and find their orientation in the developing brain. The cellular processes are depicted in brilliant detail by the new imaging technique, he notes, because of a quantum physical optics phenomenon called second harmonic generation.

"In sound waves, we can hear the second harmonic of a vibrating guitar string when the guitar body resonates and produces a tone twice as high in pitch as the original tone. The same thing happens with light waves -- although no one knew it until lasers were invented -- when a laser beam hits certain kinds of materials in our bodies," says Dombeck. "Sometimes a second harmonic is generated at exactly twice the energy, or half the wavelength, of the original light. Microtubules with uniform polarity generate a second harmonic, but microtubules with mixed polarity don’t. We get destructive interference instead, so that axons light up, and dendrites and everything else with nonuniform polarity in the microtubules stay dark."

To demonstrate the imaging system, the biophysicists depicted axon bundles and individual axons in rat hippocampal brain tissue as well as axons growing from cell bodies in culture dishes. Other demonstrations in non-neuronal structures showed microtubules in the mitotic spindles of dividing cells, and microtubule-based cilia that line the inner walls of the aquaductus cerebri and waggle to propel fluid through the brainstem. When individual, successive images are assembled into a video, cell division can be followed and the fluid-propelling motion of brainstem duct cilia can be studied in detail.

At the most fundamental level, imaging studies might explain the role of microtubule-polarity in developing brain tissue, helping to decipher how the brain becomes "wired." The technique may even reveal changes in microtubule polarity, showing where, when and why neurofilamentary tangles of axons form with precipitates of tau protein in the brains of Alzheimer’s patients, giving the new technique clinical significance, Webb says.

Funding support for the microtubule polarity studies came from the National Science Foundation, National Institutes of Health, Hellmuth Hertz Foundation, Wenner-Gran Foundation and the Alzheimer’s Association.

David Brand | Cornell News
Further information:
http://www.news.cornell.edu/releases/June03/microtubule.hrs.html
http://www.drbio.cornell.edu/drbio.html
http://www.aep.cornell.edu/eng10_page.cfm

More articles from Life Sciences:

nachricht Antimicrobial substances identified in Komodo dragon blood
23.02.2017 | American Chemical Society

nachricht New Mechanisms of Gene Inactivation may prevent Aging and Cancer
23.02.2017 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

From rocks in Colorado, evidence of a 'chaotic solar system'

23.02.2017 | Physics and Astronomy

'Quartz' crystals at the Earth's core power its magnetic field

23.02.2017 | Earth Sciences

Antimicrobial substances identified in Komodo dragon blood

23.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>