Cincinnati -- A team of scientists from the University of Cincinnati, the Jackson Laboratory in Bar Harbor, Maine and Northern Illinois University have mapped the first gene known to cause age-related hearing loss in mice.
The researchers reported in the current issue of the journal Hearing Research that they used microsatellite DNA markers to map the age-related hearing loss (Ahl) gene to mouse Chromosome 10. Ahl appears be to a single gene, recessive trait.
The researchers worked with the C57BL/6J inbred strain of mice, the most commonly studied strain in age-related hearing loss research. Its abbreviated name is the B6 mouse.
Larry Erway, professor of biological sciences at the University of Cincinnati, said the mapping work involved traditional and time-consuming genetic crosses as well as the newer DNA microsatellite techniques.
"We started the genetic cross in 1991," said Erway. The mice were produced at the Jackson Laboratory and sent here. I reared the animals and aged them to two years of age."
Tissue samples demonstrated that the Ahl gene was on Chromosome 10, but the research team then did an additional three years of work to confirm their results. This part of the research involved back-crossing the wildtype or normal gene from another strain with normal hearing to the mice with hearing loss. This produced a genetically similar, or congenic, strain with normal hearing. The only difference was the replacement of the mutant Ahl gene with the gene for normal hearing. Because the new congenic strain had normal hearing, and the only difference between the two strains was a single stretch of Chromosome 10, that was further evidence of the location of the Ahl gene.
The researchers used two different techniques to document
hearing loss in the mice. The first is called ABR for auditory-
evoked brainstem response which measures the reception and
transmission of nerve signals in the brain. As mice lose their
hearing, it requires a louder a
Contact: Chris Curran
University of Cincinnati