842-B 22 MAY 2020 • VOL 368 ISSUE 6493 sciencemag.org SCIENCE
RESEARCH
;SOCIAL ENVIRONMENT
Social animals need
connection
Much research over the past
decade or so has revealed that
health and lifespan in humans,
highly social animals, are
reduced with social adversity.
We humans are not the only
animals that are social, however,
and similar research has shown
that other social mammals are
similarly influenced by isolation
and adversity. Snyder-Mackler
et al. reviewed the relationships
between social environment
and many aspects of health and
well-being across nonhuman
mammals and investigated the
similarities between these and
patterns in humans. They found
many of the same threats and
responses across social mam-
mals. —SNV
Science, this issue p. 843
MEDICINE
Correcting blindness
Retinal diseases are a major
cause of blindness but numer-
ous developments offer hope
that blindness can be reversed.
In a Perspective, Dowling
discusses advances in visual
prostheses to detect light and
transmit it to the brain, in using
gene therapy to correct inherited
blindness, and in applying regen-
erative approaches, including
the implantation of stem cells,
to restore visual circuitry. Many
of these approaches are being
tested in the clinical setting, and
if they are successful, sight could
be restored in a substantial num-
ber of patients blinded by retinal
diseases. —GKA
Science, this issue p. 827
CORONAVIRUS
Drug repurposing
Given the urgent need to find
treatments for cases of severe
coronavirus disease 2019
(COVID-19), repurposing of exist-
ing drugs known to be safe in
humans could be a promising
option. In a Perspective, Guy et
al. discuss the underlying ratio-
nale for, and how to prioritize,
testing of drugs developed for
other applications. Considering
the coronavirus replication cycle,
certain drugs such as hydroxy-
chloroquine, chloroquine, and
remdesivir could have promis-
ing activity against COVID-19.
However, the authors urge
caution in relying on studies in
cells and results from prelimi-
nary clinical trials involving small
numbers of patients. Moreover,
the side effects of some of these
drugs should also be balanced
against possible gains. —GKA
Science, this issue p. 829PLANT SCIENCE
Fungal disease meets
its match
Fusarium head blight (FHB),
caused by a fungus, reduces
wheat crop yield and introduces
toxins into the harvest. From
the assembly of the genome
of Thinopyrum elongatum, a
wild relative of wheat used in
breeding programs to improve
cultivated wheat, Wang et
al. cloned a gene that can
address both problems (see
the Perspective by Wulff and
Jones). The encoded glutathione
S-transferase detoxifies the
trichothecene toxin and, when
expressed in wheat, confers
resistance to FHB. —PJH
Science, this issue p. 844;
see also p. 822WATER RESOURCES
Dowsing for danger
Arsenic is a metabolic poison
that is present in minute quanti-
ties in most rock materials and,
under certain natural conditions,
can accumulate in aquifers and
cause adverse health effects.
Podgorski and Berg used
measurements of arsenic in
groundwater from ~80 previous
studies to train a machine-
learning model with globally
continuous predictor variables,including climate, soil, and
topography (see the Perspective
by Zheng). The output global
map reveals the potential for
hazard from arsenic contami-
nation in groundwater, even in
many places where there are
sparse or no reported measure-
ments. The highest-risk regions
include areas of southern and
central Asia and South America.
Understanding arsenic hazard
is especially essential in areas
facing current or future water
insecurity. —MAF
Science, this issue p. 845;
see also p. 818TOPOLOGICAL OPTICS
Topological insulators go
nonlinear
Whereas solid-state insulators
tend to be fixed by material
properties, photonic topologi-
cal insulators can be designed
at will to mimic a variety of
scenarios and complex interac-
tions. Mukherjee and Rechtsman
go beyond the linear optical
regime that has been studied
to date and show that photonic
topological insulators can also
exhibit nonlinear optical features
(see the Perspective by Ablowitz
and Cole). Their array of laser-
written waveguides can support
solitons, which are also found
to exhibit topological features,
performing cyclotron-like orbits
associated with the topology of
the lattice. The nonlinear proper-
ties provide a rich playground
for further exploration, with the
possibility of mimicking other
interacting bosonic systems.
—ISO
Science, this issue p. 856;
see also p. 821METROLOGY
Good timing for
microwave technology
Timing standards around the
world define the second using
atomic clocks, specifically the
microwave frequencies emittedfrom trapped atoms. Optical
clocks, which are based on opti-
cal transitions of atoms, operate
at much higher frequency and
have been shown to exhibit
better stability. Nakamura et al.
demonstrate a framework that
carries the improved stability
of the optical domain over to
microwaves (see the Perspective
by Curtis). In addition to
contributing to the eventual
redefinition of the second based
on optical clocks, this work will
also lead to improvements in
microwave-based technologies
such as astronomical imaging
and geodesy through very long
baseline interferometry, radar,
communications, and navigation
systems. —ISO
Science, this issue p. 889;
see also p. 825DEVICE TECHNOLOGY
DNA bricks build
nanotube transistors
Semiconducting carbon nano-
tubes (CNTs) are an attractive
platform for field-effect tran-
sistors (FETs) because they
potentially can outperform
silicon as dimensions shrink.
Challenges to achieving superior
performance include creating
highly aligned and dense arrays
of nanotubes as well as removing
coatings that increase contact
resistance. Sun et al. aligned
CNTs by wrapping them with
single-stranded DNA handles and
binding them into DNA origami
bricks that formed an array of
channels with precise intertube
pitches as small as 10.4 nanome-
ters. Zhao et al. then constructed
single and multichannel FETs
by attaching the arrays to a
polymer-templated silicon wafer.
After adding metal contacts
across the CNTs to fix them to
the substrate, they washed away
all of the DNA and then deposited
electrodes and gate dielectrics.
The FETs showed high on-state
performance and fast on-off
switching. —PDS
Science, this issue p. 874, p. 878Edited by Michael FunkALSO IN SCIENCE JOURNALS
Published by AAAS