WASHINGTON, Nov. 2 (Xinhua) -- Scientists at the
University of Liverpool in Britain have discovered that mice rely on a special
set of proteins to recognize each other, the U.S. journal Current Biology
reported on Friday.
Previous study assumed that another set of genes that
influences mell in vertebrates might be used by animals that identify each other
through scent.
The team found, however, that mice use a highly
specialized set of proteins in their urine to recognize different individuals,
suggesting that this may also be true of other animals.
For many years scientists assumed that a particular
set of genes, called the major histocompatibility complex (MHC), helped animals
to identify individuals within their own species through their scent. Each
individual has a different MHC code. It influences the body's odor and it was
assumed that animals that are sensitive to scents would use these different
odors to recognize each other.
"We found, however, that while female wild mice do
indeed use scent to identify individual males, MHC does not play a part," said
lead author Jane Hurst.
To test this theory, scientists observed how female
mice identify potential mates. Female mice distinguish between dominant and
weaker males, by how fresh a male scent-mark is. A dominant male is able to
scent-mark a territory after excluding its other male competitors, allowing it
to leave a more recent scent-mark than any of its competitors.
The group demonstrated that when faced with two males
with different MHC types, females cannot identify which male left the fresh
territory scents and which left the older scents, indicating that MHC
differences are not sufficient for individual recognition as previously thought.
Instead, they found that a special set of proteins in
the urine of mice allows females to recognize which individual male is dominant.
Professor Hurst added: "These major urinary proteins
(MUPs) actlike a 'chemical barcode' of individual identity. Each individual has
a slightly different set of proteins, allowing each animal to be easily
recognized."
