Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


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


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:

More articles from Health and Medicine:

nachricht NIH scientists describe potential antibody treatment for multidrug-resistant K. pneumoniae
14.03.2018 | NIH/National Institute of Allergy and Infectious Diseases

nachricht Researchers identify key step in viral replication
13.03.2018 | University of Pittsburgh Schools of the Health Sciences

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: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

TRAPPIST-1 planets provide clues to the nature of habitable worlds

21.03.2018 | Physics and Astronomy

The search for dark matter widens

21.03.2018 | Materials Sciences

Natural enemies reduce pesticide use

21.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>