Wheel-running mice have helped scientists to identify an altered body clock gene that can make a normal day up to three hours longer.
The altered gene, named 'after hours' or Afh, is a variant of a gene called Fbxl3 which was previously unknown to play a role in keeping mammals internal body clocks running on time.
The discovery was a team effort involving scientists from the Medical Research Council Mammalian Genetics Unit, the MRC Laboratory for Molecular Biology and colleagues based at New York University. The results are published in Science.
By monitoring when and how often the mice chose to run on an exercise wheel the team spotted an alteration in some of the animals' normal rhythms. Instead of following the typical 24-hour-pattern, some of the mice had body clocks that stretched to up to a 27-hour-day.
Closer study of the DNA from the mice then revealed that those on a 27-hour-cycle had the after hours version of the Fbxl3 gene, one of a large family of genes that control the breakdown of specific proteins within body cells.
Dr Patrick Nolan, of the MRC Mammalian Genetics Unit, who led the study said:
‘‘The internal body clocks of mice with the after hours gene run on a longer cycle than mice that have a normal copy of the gene, who like most of us live on a 24-hour-schedule.''
Explaining the finding, he described how the gene might have an effect on the body clock: