It’s a jungle on there: Skin samples
contain rich diversity of bacteria
inventory identifies body’s most microbe-varied locales
News Briefs
skin’s protective barrier. But not every-
By Tina Hesman Saey
one who has the filaggrin variation will
PHILADELPHIA — Most people think get eczema. The new inventory of bac-
of rain forests as hot spots for biologi- teria could help researchers determine
cal diversity, but new research suggests whether people with eczema have an
that belly buttons are also rich ecosys- overactive immune response to bacteria
tems. That’s one finding from the first living on their skin, Chapman says.
attempt to take a large-scale inventory In the new study, dermatologists col-
of microbes on human skin. lected skin scrapings from 21 places on
In recent years scientists have come the bodies of 10 healthy volunteers. Grice
to appreciate people as super organisms, and her colleagues examined genetic
composed not just of human tissue, but diversity in the 16S ribosomal RNA gene
also of microbes galore. Human skin is in bacteria in the samples. Scientists can
covered by a variety use variations in this
of bacteria, viruses, gene to distinguish
fungi and mites, says one type of bacteria
Elizabeth Grice of from another, and the
the National Human technique has been
Genome Research used to sample bac-
Institute in Bethesda, teria living in oceans,
Md. Most of the time, human and mouse
people and their intestines, and even
microbes live in har- Only about 1 percent of bacteria on shower curtains
mony, but people with can be grown in the lab (shown), so and toothbrushes.
skinconditionssuchas scientists are using genomics to Among the most
eczema often struggle figure out what lives on the skin. diverse spots were the
with skin infections. belly button, inner
“The skin is two square meters of forearm, buttocks, theskinbetweenthe
ecosystem,” Grice said November 13 at fingers and the gluteal crease (also known
a meeting of the American Society of as the plumber’s crack). Other body parts
Human Genetics. had a relative dearth of bacterial diver-
Grice presented work she and her col- sity. Cold spots were the greasy spot just
leagues have done to catalog the diver- behind the ear, the crease on the side of
sity of bacteria living on human skin. The the nose, the toe webs and the sternum.
findings could help doctors and scien- A few spots on some volunteers had
tists better understand why some people up to 300 different species of bacteria,
develop skin conditions such as eczema Grice says. Other areas contained as few
and psoriasis while others with similar as three types. The amount of diversity
genetic backgrounds do not. not only varied from body part to body
“We know there is a genetic compo- part, but also from person to person.
nent”toeczema,says Kimberly Chapman The researchers plan to test the
of the Children’s Hospital of Philadelphia, healthy volunteers again in six months
who was not involved in the research. and to recruit volunteers with eczema to
Some people with eczema have a defect see if they have different types of bacte-in filaggrin, a protein that helps form the ria on their skin.
Cancer genome sequenced
For the first time, a complete cancer
genome, and incidentally a complete
female genome, has been decoded,
scientists report online november 5
in Nature. in a study made possible
by faster, cheaper and more sensitive Dna sequencing methods, the
researchers pinpointed eight new
genes that may cause a cell to turn
cancerous. “We need to know the
genetic rules of cancer,” says coauthor
Timothy ley of Washington University
in st. louis. — Laura Sanders
Different division
PHilaDElPHia — Women and men
sometimes do things differently,
right down to divvying up their
genetic legacies. This divvying up is
known as meiosis, a process that
cuts the number of chromosomes
in half during the production of eggs
and sperm. Men do meiosis by the
textbook, but women play it looser
with the process, Terry Hassold of
Washington state University in Pull-
man reported november 12 at the
annual meeting of the american
society of Human Genetics.
in men, chromosome pairs zip
themselves tightly together all along
their length. But in women, Hassold
and his colleagues saw “split ends”
and “bubbles” where the chromo-
somes were not tightly joined. and
women’s chromosomes had fewer
recombination points than expected.
about 5 percent of the pairs of chro-
mosome 21 that were examined had
no evidence of recombination.
recombination is necessary for
proper chromosome segregation,
so the finding could help explain
why women sometimes pass along
the wrong number of chromosomes
to their children, Hassold reported.
