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.

PH

OT

OS

(F

RO

M L

EF

T):

CH

EN

PE

LL

ED

/AL

AM

Y S

TO

CK

PH

OT

O;

AN

DR

EY

NE

KR

AS

OV

/AL

AM

Y S

TO

CK

PH

OT

O

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).

CR

ED

ITS

(F

RO

M T

OP

): S

HU

ET

AL

., E

NV

IRO

N.

SC

I. T

EC

HN

OL

. L

ET

T.;

RO

BE

RT

MA

RK

US

/S

CIE

NC

E S

OU

RC

E

A light micrograph of pancreatic islets,

which house insulin-producing b cells

1002 2 SEPTEMBER 2016 • VOL 353 ISSUE 6303

Published by AAAS