Just passing through - Science · through-guts. GUT EVOLUTION OJust passing through ur...
Transcript of Just passing through - Science · through-guts. GUT EVOLUTION OJust passing through ur...
2 SEPTEMBER 2016 • VOL 353 ISSUE 6303 1001SCIENCE sciencemag.org
antibodies may block the virus
in multiple sites throughout the
body, rather than just at the site
of entry. —KLM
Science, this issue p. 1045
IMMUNOLOGY
Divergent responses, same receptorMacrophages detect infection
or tissue injury with pattern
recognition receptors, including
the Toll-like receptors (TLRs).
Piccinini et al. investigated
how macrophages react to
the bacterial product lipo-
polysaccharide (LPS) and the
extracellular matrix component
tenascin-C, both of which stimu-
late TLR4. Although both stimuli
activated some common signal-
ing pathways, LPS stimulation
predisposed macrophages to
destroy the extracellular matrix,
whereas tenascin-C stimula-
tion induced macrophages to
synthesize matrix components.
Thus, diverse stimuli can trigger
the appropriate inflammatory
or tissue-repair response, even
though they activate the same
receptor. —JFF
Sci. Signal. 9, ra86 (2016).
GLOBAL CHANGE BIOLOGY
Trees surge on the Tibetan PlateauSo many factors affect tree
growth that it is almost impos-
sible to develop a concise idea
of how forests will respond to
global change. Accelerating tree
growth on the Tibetan Plateau
provides an opportunity to
Edited by Kristen Mueller
and Jesse Smith IN OTHER JOURNALS
CELESTIAL MECHANICS
The closest quasi-satellite to EarthA quasi-satellite orbits close to
a planet, circling the Sun with
the same orbital period, but it is
not gravitationally bound to the
planet. The fifth known quasi-
satellite of Earth was discovered
earlier this year: an asteroid
with the snappy name (469219)
2016 HO3. In a recent study, de la
Fuente Marcos and de la Fuente
Marcos investigated its orbit with
numerical simulations, showing
that it will remain an Earth quasi-
satellite for a few centuries. The
asteroid, which is a few dozen
meters across, stays between 38
and 100 times as far away from
Earth as the Moon. This proximity
and its low relative velocity make
the object a tempting target for a
visit by a sample-return mission—
or even by astronauts. —KTS
Mon. Not. R. Astron. Soc. 10.1093/
mnras/stw1972 (2016).
explore the issue. Silva et al.
analyzed stable isotopes of
carbon, oxygen, and nitrogen
in the rings of trees from Tibet
to understand why there has
been a recent surge in growth
during the past ~250 years.
Elevated CO2, changes in water
use efficiency, and perma-
frost thawing may explain the
enhanced growth. —SN
Sci. Adv. 10.1126.sciadv.1501302
(2016).
TEXTILES
Keeping cool without losing your shirtPeople use clothing to retain
warmth in cold weather. But
what about clothing to keep us
cool when it is hot? The chal-
lenge is to find a material that
lets radiation from the human
body pass through but that is
opaque to visible light. Hsu et
al. have created a nanoporous
polyethylene textile that has
both of these characteris-
tics (see the Perspective by
Boriskina). The key feature
of the material is the pore
size, which can be tuned to
absorb visible light while being
almost invisible to mid-infrared
radiation. The material is
water-wicking and strong and
keeps skin much cooler than
cotton. —BG
Science, this issue p. 1019;
see also p. 986
ORGANIC CHEMISTRY
Copper-catalyzed radical relayBreaking C-H bonds can
produce highly reactive carbon
radicals that enzymes can use
to form new bonds to such car-
bon centers. Zhang et al. show
that when the radicals escape
the environs of their forma-
tion, a copper catalyst can also
finely direct their reactivity.
Chiral ligands on copper guide
the asymmetric addition of
a CN group to form a nitrile
product with high enantiose-
lectivity that can be used for
pharmaceutical intermediates.
—JSY
Science, this issue p. 1014
Tibet’s trees are experiencing a
growth spurt.
Comb
jellies have
through-guts.
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GUT EVOLUTION
Just passing through
Our understanding of how guts evolved has included a
long-held misconception. Despite reports dating back
to the 1800s of a gut with more than one opening in
metazoans (jellies and comb jellies), textbooks often
present this group as having a sac-like gut with only
one opening. Presnell et al. housed two species of comb jellies
under laboratory conditions and captured high-resolution
images of their feeding and excretion. Their detailed imaging
revealed that comb jellies do not excrete through the mouth
but rather through multiple anal pores, confirming that they do
indeed possess a through-gut. These results suggest that our
understanding of gut evolution may require a rethink. —SNV
Curr. Biol. 10.1016/j.cub.2016.08.019 (2016).
Published by AAAS
RESEARCH | IN OTHER JOURNALS
sciencemag.org SCIENCE
BIOPHYSICS
Mechanical coupling of heart cellsMyocytes in adult hearts control
the heartbeat through electri-
cal signaling, which propagates
contractions to neighboring cells.
However, Chiou et al. now report
that the developing heart may
use mechanical coupling between
myocytes instead. The authors
were able to explain the behav-
ior of embryonic hearts with a
model that considers myocytes
as mechanically excitable cells
that contract when exposed to a
sufficient strain. Moreover, block-
ing ion exchange in hearts from
chicken embryos did not prevent
coordinated beating. Thus, the
authors propose that the heart’s
first beats reveal a second mecha-
nism for coordination that could
be relevant to the development
of stem cell–based therapies for
damaged heart tissue. —LBR
Proc. Natl. Acad. Sci. U.S.A. 10.1073/
pnas.1600362113 (2016).
METABOLIC DISEASE
Pacemaker cells for insulin releasePancreatic islets keep blood
glucose levels in check. When
glucose is too high, β cells within
the islets release insulin, which
promotes glucose removal from
the blood. But Johnson et al.
now find that not all β cells play
an equal role in this process.
Optogenetic and photo-pharma-
cological methods revealed that
mouse islets contain a handful
of specialized β cells or “hubs”
with pacemaker properties.
Representing 1 to 10% of total β
cells, hubs functionally wire the
islets to coordinate responsive-
ness to glucose. Exposure to
a proinflammatory milieu, a
condition associated with type
2 diabetes, caused hub failure
and collapse of islet function.
Hub failure may thus underlie
defective insulin release in this
disorder. —PAK
Cell Metab. 10.1016/j.
cmet.2016.06.020 (2016).
INNOVATION ECONOMICS
Measuring impacts of technology on growth Schumpter’s concept of
“creative destruction” reflects
how technological innovation
plays a key role in a dynamic
economy. Questions remain,
though, about how to mea-
sure the scientific versus the
economic impact of a technol-
ogy. Kogan et al. created a new
measure based on identifying
U.S. stock market responses
to the announcement of new
U.S. patents from 1926 to 2010.
Compared with basic cita-
tion metrics, their measure
is a better predictor of firms’
innovation-driven growth. Firms
that experience a one-standard-
deviation increase in innovation
output show 2 to 5% growth over
the next 5 years. Firms that do
not innovate in an industry that
experiences a one-standard-devi-
ation increase in innovation
see their growth decrease by 2 to
5% over the same period. —BW
Quart. J. Econ., in press;
http://papers.ssrn.com/sol3/papers.
cfm?abstract_id=2193068.
NEUROSCIENCE
Brain mapping by barcodeMapping how neurons function-
ally connect over long distances
promises to offer important
insights into brain function.
Although optical and fluorescent
labeling techniques have provided
key information, Kebschull et al.
report a new approach called
MAPseq that capitalizes on the
high throughput of nucleic acid
sequencing. A viral vector is used
to deliver multiple barcoded RNA
fragments into individual neurons.
The neurons then transport
individual RNA barcodes into the
axons that they extend, where
they can be recovered, allowing
for the mapping of thousands of
single neuron projections. To test
the system, the authors mapped
the projections from individual
neurons of the locus coeruleus, a
region of the brain that provides
noradrenaline to the neocortex.
—BJ
Neuron 10.1016/j.neuron.2016.07.036
(2016).
Hydrological units with detectable PFASs
Detected
Not detected
No data
WATER QUALITY
Drinking water—and what else?
Poly- and perfluoroalkyl substances
(PFASs) are everywhere, and they are
persistent. Exposure to these com-
pounds has been linked to several
adverse health effects, so identification
of especially vulnerable populations is
urgently needed. Hu et al. performed a
spatial analysis of PFASs in U.S. drinking
water. Higher reported PFAS levels were
associated with manufacturing sites
and military fire training facilities. In
total, water supplies serving 16 million
residents contained PFASs at or near
minimum reporting levels. Because
many U.S. residents rely on undersam-
pled private wells or small public water
supplies, exposure from drinking water
remains unknown for nearly one-third of
the U.S. population. —NW
Environ. Sci. Technol. Lett. 10.1021/acs.
estlett.6b00260 (2016).
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A light micrograph of pancreatic islets,
which house insulin-producing b cells
1002 2 SEPTEMBER 2016 • VOL 353 ISSUE 6303
Published by AAAS