Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Inner ear of chicken yields clues to human deafness and balance disorders

23.05.2003


Scientists at Washington University School of Medicine in St. Louis have gained new insights into the causes of human deafness and balance disorders by studying the inner ear of chickens.



The research provides new clues as to why birds can replace critical cells in the inner ear and humans cannot. Loss of these so-called sensory hair cells in humans is a leading cause of deafness and impaired balance due to aging, infectious disease and exposure to loud noise. The study will be published in the June 1 issue of the journal Human Molecular Genetics and appears online today.

The team measured the activity of more than 1,800 genes in sensory cells from two regions of the chicken inner ear: the cochlea, where sound is converted into nerve impulses, and the utricle, where balance is sensed. The utricle of birds replaces sensory cells regularly, while the cochlea replaces them when they die. The investigators discovered more than 100 significant differences between the two regions.


The findings provide new insights into the causes of deafness due to aging and the loss of these essential cells. They also may help improve knowledge of how the inner ear develops.

“Ultimately, we hope our work will lead to some form of therapy that will replace these cells when they are lost,” says lead investigator Michael Lovett, Ph.D., professor of genetics and of pediatrics and joint director of the Division of Human Genetics. “We are born with only a few thousand sensory hair cells in each ear, and to maintain hearing and balance we have to keep them for our entire lives.”

At least 30 million Americans suffer from significant hearing loss and balance disorders, Lovett says. One-third of people above age 65 and half of people above age 75 have significant hearing loss. About 80 percent of these problems result from the loss of, or damage to, sensory hair cells. “The cochlea and utricle function nearly identically in birds and humans,” says Mark E. Warchol, Ph.D., associate research scientist at the Central Institute for the Deaf and a research associate professor of otolaryngology and of anatomy and neurobiology at Washington University and a co-author of the paper. “But key differences exist between them allow birds to regenerate these cells. If we can understand those differences, perhaps we can learn how to replace lost or damaged sensory hair cells in humans.”

The investigators used microarray technology to compare the activity of genes from the cochlea and utricle of chickens. Microarrays allow the comparison of thousands of genes at one time to determine which genes are active. Lovett’s group constructed one microarray containing 426 human genes known to be involved in hearing or to be active in the inner ear. A second microarray held 1,422 human genes for transcription factors, proteins that latch onto genes to turn them on or off. The investigators had to use human genes because few genes in the chicken have been identified. (That situation will change with the mapping of the chicken genome, a project now under way at Washington University’s Genome Sequencing Center.)

Warchol’s laboratory isolated and grew the chicken sensory hair cells, then Lovett’s group isolated messenger RNA from these few thousand cells. Messenger RNA is a shortened copy of an active gene, but there are only tiny quantities in the relatively small number of hair cells from each ear. Lovett’s group therefore used special amplification methods that they developed to make multiple copies of each messenger RNA. Each copy of a messenger RNA clings to its corresponding gene on a microarray and thereby labels the gene with its fluorescent dye.

The microarrays used by Lovett and his colleagues showed that about 600 transcription-factor genes were active to some degree in both the chicken cochlea and utricle, and that about 40 were active in only one area. They also identified 20 inner-ear genes and more than 80 transcription-factor genes that differed in their activity levels between the two areas.

Among the study’s surprising findings was that a gene known as GATA3 may be involved in orienting sensory hair cells in the utricle, and that the gene for beta amyloid, which is implicated in the death of neurons during Alzheimer’s disease, is active in the chicken utricle.

“We have no idea yet how important or significant this may be,” Warchol says, “but like much of what we found in this study, it’s a new lead that we want to pursue.”


###

Hawkins RD, Bashiardes S, Helms CA, Hu L, Saccone NL, Warchol ME, Lovett M. Gene expression differences in quiescent versus regenerating hair cells of avian sensory epithelia: implications for human hearing and balance disorders. Human Molecular Genetics, June 1, 2003.

A grant from the National Organization for Hearing Research Foundation supported this research.

The full-time and volunteer faculty of Washington University School of Medicine are the physicians and surgeons of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is one of the leading medical research, teaching and patient-care institutions in the nation. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.

Darrell E. Ward | EurekAlert!
Further information:
http://medinfo.wustl.edu/

More articles from Health and Medicine:

nachricht Organ-on-a-chip mimics heart's biomechanical properties
23.02.2017 | Vanderbilt University

nachricht Researchers identify cause of hereditary skeletal muscle disorder
22.02.2017 | Klinikum der Universität München

All articles from Health and Medicine >>>

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

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>