SCIENCE sciencemag.org 4 JANUARY 2019 • VOL 363 ISSUE 6422 39

RESEARCHEdited by Stella Hurtley

I N SC IENCE J O U R NA L S

VIROLOGY

Mobile detection of Lassa virus Lassa fever is a hemorrhagic viral

disease endemic to West Africa.

Usually, each year sees only a

smattering of cases reported, but

hospitalized patients risk a 15%

chance of death. Responding to

fears that a 10-fold surge in cases

in Nigeria in 2018 signaled an

incipient outbreak, Kafetzopoulou

et al. performed metagenomic

nanopore sequencing directly

from samples from 120 patients

(see the Perspective by Bhadelia).

Results showed no strong

evidence of a new strain emerg-

ing nor of person-to-person

transmission; rather, rodent

contamination was the main

source. To prevent future escala-

tion of this disease, we need to

understand what triggers the

irruption of rodents into human

dwellings. —CA

Science, this issue p. 74;

see also p. 30

PROTEIN TRANSLOCATION

Posttranslational translocon architectureAbout a third of proteins are

transported into endoplasmic

reticulum by the universally

conserved Sec61 protein-

conducting channel. Itskanov

and Park determined a cryo–

electron microscopy structure

of the Sec complex from yeast,

which mediates posttranslational

translocation of many secretory

proteins across the endoplasmic

reticulum membrane. The study

reveals how Sec63 activates

the Sec61 channel for substrate

polypeptide insertion. The

structure also explains the

mutually exclusive binding of

Sec63 and the ribosome to the

channel. —SMH

Science, this issue p. 84

CHEMICAL PHYSICS

C60 at high resolution It generally takes more energy

for molecules to vibrate than to

rotate. A vibrational absorption

band thus encompasses many

distinct concurrent rotational

transitions, but these tend to blur

together when the molecules

have more than a few atoms.

Changala et al. succeeded in cool-

ing C60

fullerenes sufficiently to

obtain rotational resolution within

a C–C stretching band. Success

hinged on careful optimization

of argon buffer gas flow. Such

quantum state–resolved features

could aid characterization of

fullerene-type compounds in

exotic environments such as

interstellar space. —JSY

Science, this issue p. 49

ATOMIC PHYSICS

Making a strongly coupled plasma Plasmas—gases of ionized

atoms and electrons—are

naturally formed at high temper-

atures, such as those reached in

the interiors of stars. Describing

plasmas theoretically is tricky

when they are in the strongly

coupled regime; reaching that

regime in the laboratory would

provide a valuable benchmark

for theory. To that end, Langin

et al. worked with a cold plasma

created out of atoms of stron-

tium that were ionized by laser

light (see the Perspective by

Bergeson). They used lasers to

cool the ions down to about 50

CROWD DYNAMICS

A crowd that flows like water

The behavior of large numbers of insects, animals, and

other flocks is often based on rules about individual inter-

actions. Bain and Bartolo applied a fluid-like model to the

behavior of marathon runners as they walked up to the

start line of the Chicago Marathon (see the Perspective by

Ouellette). They observed nondamping linear waves with the

same speed for different starting corrals of runners and at dif-

ferent races around the world. Their model should apply both

to this type of polarized crowd as well as to other groups, which

may help guide crowd management. —BG

Science, this issue p. 46; see also p. 27

Runners moving down Columbus Drive at the Chicago Marathon, October 2017

Fluorinated aryl groups couple to form nanographenes Kolmer et al., p. 57

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sciencemag.org SCIENCE40 4 JANUARY 2019 • VOL 363 ISSUE 6422

millikelvin, reaching the desired

strongly coupled regime. —JS

Science, this issue p. 61;

see also p. 33

PALEONTOLOGY

A proto-mammalian giant Early terrestrial amniotes evolved

into two groups: the sauropsids,

which led to the bird and dinosaur

lineages, and the synapsids,

which led to mammals. Synapsids

were diverse during the Permian

but were greatly reduced after the

end-Permian extinction (about

252 million years ago). The few

groups that survived into the

Triassic were mostly small and

retained a sprawling gait. Sulej

and Niedźwiedzki, however,

describe a dicynodont from

the Late Triassic of Poland that

is as large as some coexisting

dinosaurs and appears to have

had an erect gait—like modern

mammals. Thus, megaherbivores

in the Triassic were not only dino-

saurs. —SNV

Science, this issue p. 78

SOCIAL SCIENCES

Deadliest 100 days of the HolocaustMore than 25% of the approxi-

mately 6 million Jews murdered

during the Holocaust were killed

in one 100-day period in 1942.

Stone used an unusual dataset

of railway transportation records

to show that during this period,

the Nazis murdered more than

1.47 million Jews, a kill rate that

is 10 times higher than previous

estimates. Contradicting contem-

porary analyses of the Holocaust,

the author shows that Operation

Reinhard was exceptionally

violent in its extreme kill rate,

number, and proportion of the

population murdered, even when

compared to other 20th-century

genocides. —PJB

Sci. Adv. 10.1126/

sciadv.aau7292 (2018).

PROKARYOTIC IMMUNITY

Additional, diverse CRISPR systems CRISPR systems have been

revolutionizing molecular biol-

ogy. Mining the metagenomic

database, Yan et al. system-

atically discovered additional

subtypes of type V CRISPR-Cas

systems. The additional Cas12

effectors displayed a range of

activities, including target and

collateral cleavage of single-

stranded RNA and DNA, as well as

double-stranded DNA nicking and

cleavage. These diverse nuclease

activities suggest how an ancient

transposase may have evolved

into various type V effectors and

expand the nucleic acid detec-

tion and genome-editing toolbox.

—SYM

Science, this issue p. 88

DRUG DEVELOPMENT

A long-lasting poison scavengerNerve agents are neurotoxic

compounds found in pesticides

and chemical weapons. They

act by blocking the transmis-

sion of nerve impulses to the

muscles, and exposure can be

fatal within minutes. Zhang et al.

developed a nanoparticle-based

bioscavenger that breaks down

organophosphate nerve agents

into innocuous compounds.

Prophylactic treatment of rats

and guinea pigs confirmed

low immunogenicity

and good biodistribu-

tion. Treated animals

were protected from

repeated exposure

to the nerve agent

sarin over 7 days. This

nanoscavenger might

thus help prevent nerve-

agent poisoning in

at-risk subjects. —MM

Sci. Transl. Med. 11,

eaau7091 (2019).

HUMAN GENETICS

Alzheimer’s disease in admixed peopleSeveral genes have been identi-

fied that increase the risk of

late-onset genetic disorders,

such as Alzheimer’s disease

(AD). Specifically, the ApoE «4

allele is associated with a higher

risk of developing AD. However,

individuals of African ancestry

that carry this variant appear

to be less prone to developing

AD. Rajabli et al. examined AD

cases and controls in admixed

individuals of Puerto Rican

and African-American descent

and found that individuals who

carried an African ApoE «4

background had less risk of

developing the disease. It seems

the African variant of ApoE «4

contains protective genetic

variants. —LMZ

PLOS Genet. 14, e1007791 (2018).

PLANT SCIENCE

Essential metal for plantsAlthough zinc (Zn) is an essen-

tial micronutrient for plants and

humans, much of the world’s

agricultural land is deficient in Zn.

Sinclair et al. studied plants that

are unable to deliver Zn into their

own xylem. The plant shoots were

thus internally starved regardless

of whether Zn was available from

the root. The Zn-starved shoots

signaled to roots to increase Zn

supplies. In response, the roots

up-regulated expression of the

genes encoding metal transport/

tolerance protein 2 (MTP2) and

heavy metal ATPase 2 (HMA2).

Local Zn deficiency in roots left

these same genes unaffected. It

seems that Zn taken up in lateral

roots is transported into the

endoplasmic reticulum by MTP2,

thus gaining access to the inter-

cellular symplastic network. The

Zn then progresses from outer

epidermal cells toward the core

of the root, where it is exported

by HMA2 into the xylem for trans-

port to the shoot. The shoot asks

for what it needs, and the root

delivers. —PJH

Plant Cell 30, 2463 (2018).

SKIN

Roots of acne Most people experience a bout

of acne at some stage in their

life. For an unlucky few, the skin

Edited by Caroline Ash

and Jesse SmithIN OTHER JOURNALS

Transport records have been analyzed to

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RESEARCH | IN SCIENCE JOURNALS

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41-B 4 JANUARY 2019 • VOL 363 ISSUE 6422 sciencemag.org SCIENCE

RESEARCH

OPTICS

Exceptional points in optics Many complex systems operate

with loss. Mathematically, these

systems can be described as

non-Hermitian. A property of

such a system is that there can

exist certain conditions—excep-

tional points—where gain and

loss can be perfectly balanced

and exotic behavior is predicted

to occur. Optical systems gener-

ally possess gain and loss and so

are ideal systems for explor-

ing exceptional point physics.

Miri and Alù review the topic of

exceptional points in photonics

and explore some of the possible

exotic behavior that might be

expected from engineering such

systems. —ISO

Science, this issue p. 42

NEUROSCIENCE

Forgetting and receptor removal The trafficking of AMPA recep-

tors to and from the surface

of postsynaptic membranes

regulates synaptic strength

and underlies learning and

memory. Awasthi et al. found

that the integral membrane

protein synaptotagmin-3 (Syt3)

is predominantly found on

postsynaptic endocytic zones

of neurons, where it promotes

AMPA receptor internaliza-

tion (see the Perspective by

Mandelberg and Tsien). In Syt3

overexpressing or knockdown

neurons, synaptic transmis-

sion and short-term plasticity

were unchanged. However, in

neurons from Syt3 knock-

out mice, synaptic long-term

depression was abolished and

decaying long-term potentiation

endured. In Syt3 knockout mice,

spatial learning was unaltered;

however, these animals showed

signs of impaired forgetting and

relearning during the water maze

spatial memory task. —PRS

Science, this issue p. 44;

see also p. 31

IMMUNOLOGY

Commensal-specific T cells are flexible Barrier tissues, like the skin, are

sites where noninvasive com-

mensal microbes constantly

interact with resident T cells.

These encounters can result

in commensal-specific T cell

responses that promote, for

example, host defense and tis-

sue repair. Harrison et al. show

that subsets of skin-resident

commensal-specific interleukin-

17A–producing CD4+ and CD8+

T cells have a dual nature:

They coexpress transcription

factors that direct antagonistic

antimicrobial (type 17) and

antiparasite and pro–tissue

repair (type 2) programs. When

skin is damaged, epithelial cell

alarmins license type 17 T cells

to turn on type 2 cytokines.

Thus, commensal-specific type

17 T cells can direct antimicro-

bial activity under homeostatic

conditions but rapidly turn on

tissue repair in the context of

injury. —STS

Science, this issue p. 43

PLANT SCIENCE

Fixing photosynthetic inefficienciesIn some of our most useful

crops (such as rice and wheat),

photosynthesis produces toxic

by-products that reduce its

efficiency. Photorespiration

deals with these by-products,

converting them into metaboli-

cally useful components, but at

the cost of energy lost. South et

al. constructed a metabolic path-

way in transgenic tobacco plants

that more efficiently recaptures

the unproductive by-products

of photosynthesis with less

energy lost (see the Perspective

by Eisenhut and Weber). In field

trials, these transgenic tobacco

plants were ~40% more produc-

tive than wild-type tobacco

plants. —PJH

Science, this issue p. 45;

see also p. 32

NANOMATERIALS

Nanographenes on oxides The growth of nanographene

islands and ribbons on metal

surfaces can be accomplished

on single-crystal metal surfaces

through carbon-carbon coupling

reactions, but the surfaces of

oxides do not assist these reac-

tions. Kolmer et al. show that

fluorinated aryl groups can be

coupled to form nanographenes

on the rutile surface of titanium

oxide. The fluorine substitution

of the aryl groups was selected

so that as the carbon-fluorine

bonds were thermally activated,

a stepwise process sequentially

added aromatic rings around

a central aryl group until it was

completely substituted. —PDS

Science, this issue p. 57

MESOSCOPIC PHYSICS

A backward current Two-dimensional materials in a

magnetic field can exhibit the so-

called quantum Hall effect. This

regime is characterized by cur-

rents running along the edge of

the sample in the “downstream”

direction determined by the sign

of the magnetic field. Lafont et

al. studied electrical transport in

GaAs-AlGaAs heterostructures,

focusing on a previously less-

studied spin-unpolarized state

in the fractional quantum Hall

regime. By considering various

experimental configurations,

they observed a component of

the charge current flowing in the

opposite, “upstream” direction.

—JS

Science, this issue p. 54

NEUROSCIENCE

Another primary visual cortex Most functional studies in the

visual system have focused on

the cortical representation of

the geniculo-striate pathway

that links the retina to the

cortex. The parallel collicular

pathway is believed to sparsely

project throughout the visual

cortex and have a modulatory

role on cortical responses to

visual stimuli. Beltramo and

Scanziani found a visual cortical

area that is entirely dedicated

to the superior colliculus. This

area can discriminate moving

visual stimuli that the “classical”

primary visual cortex cannot.

Thus, the superior colliculus, a

phylogenetically ancient struc-

ture, has its own projection in

neocortex that provides this area

with exquisite feature-detection

abilities not found in the classical

primary visual cortex. —PRS

Science, this issue p. 64

CLIMATE CHANGE

Deep Pacific cooling Earth’s climate cooled consider-

ably across the transition from

the Medieval Warm Period to

the Little Ice Age about 700

years ago. Theoretically, owing

to how the ocean circulates, this

cooling should be recorded in

Pacific deep-ocean tempera-

tures, where water that was on

the surface then is found today.

Gebbie and Huybers used an

ocean circulation model and

observations from both the end

of the 19th century and the end

of the 20th century to detect

and quantify this trend. The

ongoing deep Pacific is cooling,

which revises Earth’s overall heat

budget since 1750 downward by

35%. —HJS

Science, this issue p. 70

EVOLUTION

DNA breakage and adaptation Adaptation to new environments

often occurs in similar ways

across different colonization

events. Stickleback fish repre-

sent a classic example of this, in

which repeated colonizations of

freshwater have resulted in the

loss of pelvic hind fins. Previous

work has shown that a pelvic

enhancer gene is involved. Xie et

al. now show that this gene lies

within a region of the genome

Edited by Stella HurtleyALSO IN SCIENCE JOURNALS

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SCIENCE sciencemag.org 4 JANUARY 2019 • VOL 363 ISSUE 6422 41-C

that is prone to double-stranded

DNA breakage owing to a high

thymine-guanine content. This

enhanced region of breakage

could lead to enhanced mutation

rates that facilitate repeated

adaptations to new environ-

ments. —SNV

Science, this issue p. 81

CONSERVATION

The distinctive sound of a biodiverse forestAssessing the state of

biodiversity in a forest is a time-

consuming task that typically

requires detailed on-the-ground

surveys. In a Perspective,

Burivalova et al. explain that

recordings of soundscapes

can provide an easier route to

this information. By record-

ing soundscapes from a forest

over time and comparing them

to a regional baseline, scien-

tists can determine whether a

forest’s ecosystem is healthy

or not. If the soundscape of

a forest spared from conver-

sion becomes impoverished

and altered, an on-the-ground

survey would be warranted. This

approach may be particularly

useful for companies interested

in sustainability certification

or zero-deforestation commit-

ments. —JFU

Science, this issue p. 28

TUBERCULOSIS

Faulty kinase purged by tuberculosis?Rare mutations in genes involved

in interferon-g–dependent

immunity underpin human

genetic susceptibility to severe

mycobacterial diseases,

including primary tuberculosis.

Boisson-Dupuis et al. investi-

gated whether two common

missense variants of the TYK2

Janus kinase that have impaired

catalytic activity conferred an

increased risk of tuberculosis.

Individuals homozygous for

the P1104A (proline to alanine

substitution at residue 1104)

variant of TYK2 are markedly

predisposed to developing

primary tuberculosis, defining

a common monogenic etiol-

ogy for the “white plague.” The

current frequency of the P1104A

allele in European popula-

tions is significantly decreased

compared with its frequency in

ancient European DNA samples.

These findings suggest that

negative selection against the

TYK2 P1104A allele by endemic

tuberculosis in Europe may have

contributed to a slow genetic

purge of this susceptibility allele

during recent millennia. —IW

Sci. Immunol. 3, eaau8714 (2018).

CANCER

Altering membrane potential for cancerPolymorphisms in the G pro-

tein–coupled receptor GPR35

are associated with increased

risk for certain inflammatory

diseases that can progress to

cancer. Schneditz et al. found

that GPR35 promoted the activ-

ity of Na+- and K+-dependent

adenosine triphosphatase

(Na+,K+-dependent ATPase),

a transmembrane pump that

sets the membrane potential in

cells. This effect was enhanced

by a disease-associated GPR35

variant. Stimulation of Na+,K+-

ATPase activity by GPR35

increased glycolysis and pro-

liferation in intestinal epithelial

cells. Na+,K+-ATPase deficiency

or treatment with a pepducin

targeting GPR35 decreased

tumor burden in mouse models

of intestinal cancer. —WW

Sci. Signal. 12, eaau9048 (2019).

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