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92 FROM THE LABS
TECHNOLOGY REVIEW /
REPRINTED BY PERMISSION FROM MACMILLAN PUBLISHERS LTD: NATURE METHODS, COPYRIGHT 2007
WHY IT MATTERS: Wi-Fi tends to
be unreliable. A number of factors can
interfere with a signal, from hard-
ware malfunctions and software bugs
to interference from microwave ovens
and cordless phones. What s more, the
degree of in uence these factors have
can change quickly, making Wi-Fi fail-
ures di cult to anticipate and diag-
nose. An efficient way to pinpoint
problems would make them much
easier to correct.
METHODS: The researchers
installed 192 radios to monitor tra c
throughout the university s computer
science building. To infer wireless
activity that wasn t measured directly,
they developed novel algorithms that
extracted clues from the measured
data. Using both the measured and
the inferred data, they were able to
determine how much each interfering
factor contributed to Wi-Fi problems.
The researchers think the technology
could be implemented quickly. They
say manufacturers could easily equip
routers with tra c-monitoring hard-
ware, along with software that ana-
lyzes network activity.
NEXT STEPS: The researchers will
explore the technical challenges of
deploying the system and maintain-
ing constant network analysis.
A new fluorescent marker illuminates
tissue deep within living animals
SOU RCE: "Bright Far-Red Fluorescent
Protein for Whole-Body Imaging"
Dmitriy Chudakov et al.
Nature Methods 4: 741--746
RESULTS: Using genetic-engineering
techniques, scientists have altered a
red protein found in sea anemones to
create a uorescent marker that can
be used to study living tissue deep in
WHY IT MATTERS: The light from
existing uorescent markers is di cult
to detect through layers of tissue, so the
use of such markers has been limited to
dissected or surface tissue or to trans-
parent animals, such as wor ms. This
new marker emits light in the far-red
part of the spectrum, which can better
pass through living tissue. That means
the marker can be used in live animals
to help researchers track molecular and
cellular activity, such as the rapid divi-
sion of cancer cells, in real time.
METHODS: By inducing both ran-
dom and directed mutations in the
anemone protein, scientists altered
it to create new compounds that are
brighter than the original one. They
then tested the new proteins both in
frogs and in human cells, showing that
they shine much more brightly than
those previously available.
NEXT STEPS: Collaborators of the
scientists will soon begin testing the
proteins in mice. Although the markers
aren t bright enough for whole-body
imaging of humans, they might even-
tually be used to image human tumors
that are near the surface of the skin,
such as melanoma and breast cancer.
The First Diploid
Sequence of an
The highly accurate sequence
suggests that our genetic code is five
times as variable as we thought
SOURCE: "The Diploid Genome
Sequence of an Individual Human"
Samuel Levy et al.
PLoS Biology 5: e254
RESULTS: Genomics pioneer Craig
Venter and his colleagues have gen-
erated a highly accurate sequence of
Venter s genome, one that includes the
DNA sequences inherited from both
his mother and his father.
WHY IT MATTERS: The genome
sequence generated by the Human
Genome Project, the massive, distrib-
uted e ort to sequence human DNA
that was completed in 2003, was a
milestone in the history of biology.
But the DNA sequence produced by
the project represented just one set of
chromosomes (every human has two
sets, one inherited from each parent),
and it drew on DNA samples from
many individuals. As a result, it didn t
re ect some of the variability between
individuals. Venter s diploid genome
suggests that genetic variation between
individuals is approximately 0.5 per-
cent, not the 0.1 percent that earlier
sequencing projects suggested.
METHODS: In the new study,
researchers used a method of gene
sequencing called Sanger sequencing.
The method is more expensive than
newer approaches, but it generates lon-
ger strings of DNA that are easier to
assemble into a complete genome.
NEXT STEPS: Venter and his col-
leagues plan to add phenotypic infor-
mation, such as medical records and
physical characteristics, to the database
housing his genome. This will allow
scientists to begin analyzing an indi-
vidual s genomic information in the
context of his or her actual traits.
Scientists engineered this three-month-
old frog to make a new fluorescent
protein in its muscle tissues.
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