For more Genes & Cells stories,
visit www.sciencenews.org
African genes get shuffled faster
NEWS BRIEFS
PRDM9 works a bit like a mail carrier
delivering mail to certain addresses:
Where it stops along a chromosome,
recombination can happen. The variant
of the protein more common in people
of West African descent can read more
addresses, so it makes more stops than
the version of the protein usually found
in Europeans.
A second new map similarly found
that West Africans have a higher recombination rate than people
of European heritage.
African-American and
African-Caribbean people
have an intermediate rate,
researchers at UCLA and
collaborators report online
July 20 in Nature Genetics.
The intermediate level
is consistent with the idea
that PRDM9 is in charge of
recombination, says John
Both maps were created to improve
studies aimed at finding genes that contribute to common diseases. The results
indicate that maps for many more ethnic
groups should be made, Novembre says.
The findings might also help explain
why Africa has so much human genetic
diversity. Researchers thought it was
because people who stayed in Africa
never had their diversity reduced
through genetic bottlenecks the way
people whose ancestors migrated out of
Africa did, Reich says. The new studies
suggest that more recombination, due to
the hot spots, may also have contributed
to greater diversity, he says. s
People of
West African
ancestry have
about 2,500
recombination
hot spots that
are inactive
in people
of European
ancestry.
By Tina Hesman Saey
Two new genetic maps of African-Americans reveal that people of West
African descent have more hot spots
where chromosomes mix and match
genes than people of European heritage.
Until recently scientists knew next to
nothing about the process in humans
that mixes and matches parents’ genes to
create a unique combination in a child,
Human Genetics at Oxford
University in England.
This process, known as
recombination, also helps
chromosomes stick together
in pairs until it is time to
separate during egg and
sperm production.
Previously, scientists
could trace recombination only in families and
thought that the exchange of genetic
information happened at random. These
ne w studies are the first to describe a way
to use unrelated people to map genetic
shuffling in populations. The studies also
demonstrate that the genetic handover
actually takes place at predetermined
locations on chromosomes. “They make
real contributions to methodology, and
they really tell you something about biology,” says Spencer, who was not involved
in either study.
People of West African ancestry have
about 2,500 recombination hot spots
that are inactive in people of European
ancestry, David Reich of Harvard Medical School, Simon Myers of Oxford and a
large team of collaborators report online
July 20 in Nature.
A variant of a protein called PRDM9 is
responsible for creating the extra recombination hot spots, the team shows.
Centenarian genetics
study retracted
Scientists still can’t predict who
will live to be 100. A study pub-
lished online in Science last year
claimed to have found a genetic
signature of longevity. But other
researchers protested that techni-
cal problems invalidated the data
(SN: 7/31/10, p. 10). Researchers
at Boston University and colleagues
removed the suspect data and
reanalyzed the results. The cor-
rected findings were not strong
enough for publication in Science,
peer reviewers determined. The
journal says there was no miscon-
duct on the part of the researchers,
but asked the team to retract the
publication. The researchers
agreed but stand by their results
and say they will seek publication
elsewhere. The retraction appears
in the July 22 Science.
— Tina Hesman Saey
Eye of newt regenerates
Shakespeare’s witches might be
happy to learn that one of their
favorite ingredients is a renew-
able resource. Newts’ ability to
regenerate the lenses of their
eyes is not hampered by aging or
repeated injury, an international
team of researchers reports
online July 12 in Nature Com-
munications. Mammals, including
humans, lose the ability to renew
body parts with age, but newts
don’t seem to have that problem.
In the new study, newts regrew
lenses 18 times in 16 years, with
no loss of lens quality. Figuring
out how newts regenerate body
parts may help improve antiaging
therapies for people.
— Tina Hesman Saey
www.sciencenews.org
August 13, 2011 | SCIENCE NEWS | 17
