SCIENCE sciencemag.org 5 JUNE 2020 • VOL 368 ISSUE 6495 1078-B
CORONAVIRUS
Applications of antibody
testing
There has been a strong focus
on testing to determine whether
an individual has an active severe
acute respiratory syndrome–
coronavirus 2 (SARS-CoV-2)
infection, but how do we find out
if someone has been infected
in the past? In a Perspective,
Krammer and Simon discuss the
key applications of serological
tests to detect antibodies against
SARS-CoV-2. Serological testing
could answer key questions
about whether neutralizing
antibodies form, and if they
do, serological studies could
assess the duration of immune
protection. Such tests could
also identify recovered patients
with high amounts of antibody
who could donate blood serum
for therapeutic use. In addition,
population serosurveys could
inform mitigation practices,
which could be especially impor-
tant during subsequent predicted
waves of infection. However, it is
important to ensure that tests are
accurate and sufficiently reliable
first. —GKA
Science, this issue p. 1060
COMPUTER SCIENCE
From bottom to top
The doubling of the number of
transistors on a chip every 2
years, a seemly inevitable trend
that has been called Moore’s law,
has contributed immensely to
improvements in computer per-
formance. However, silicon-based
transistors cannot get much
smaller than they are today, and
other approaches should be
explored to keep performance
growing. Leiserson et al. review
recent examples and argue that
the most promising place to look
is at the top of the computing
stack, where improvements in
software, algorithms, and hard-
ware architecture can bring the
much-needed boost. —JS
Science, this issue p. 1079
PLASMID EVOLUTION
Agrobacteria virulence
writ large
Plasmids are widespread among
bacteria and are important
because they spread virulence
and antibiotic resistance traits,
among others. They are horizon-
tally transferred between strains
and species, so it is difficult to
work out their evolution and
epidemiology. Agrobacteria, a
diverse grouping of species that
infect plants, inject oncogenic
Ti and Ri plasmids, which
cause crown galls and hairy
root diseases, respectively. The
upside is that these plasmids
have become valuable biotech-
nological tools. Weisberg et al.
combed through an 80-year-old
collection of Agrobacterium
strains but found a surprisingly
low diversity of plasmids. It is
puzzling how limited the number
of plasmid lineages is despite
reported high levels of plasmid
recombination, but what is clear
is how plant production systems
have influenced plasmid spread
into various genomic backbones.
—CA
Science, this issue p. 1080STRUCTURAL BIOLOGY
Architecture of DNA-
organizing complex
The highly conserved mam-
malian CTC1-STN1-TEN1
(CST) complex is critical for
genome stability and telo-
mere maintenance. Lim et al.
solved the structure of the
human CST complex using
cryo–electron microscopy. CST
forms an unprecedented and
substantial decameric super-
complex triggered by telomeric
single-stranded binding. This
decameric form with single-
stranded DNA–binding capacity
of up to 10 telomeric repeats,
suggested the possibility of CST
organizing telomere overhangs
into compact and restrictive
structures in a manner similar to
the nucleosome’s organizationof double-stranded DNA. This
work provides a platform for
understanding the mechanisms
of various CST functions. —SYM
Science, this issue p. 1081CHEMICAL PHYSICS
Watching electrons
swarm ammonia
Liquid ammonia is unusual in
its capacity to host electrons in
stable solution, with vivid blue
and bronze colors signifying the
low- and high-concentration
regimes, respectively. Buttersack
et al. used photoelectron spec-
troscopy and accompanying
theoretical simulations to track
the precise energetic changes
that ensued as steadily rising
quantities of electrons were
introduced by dissolved lithium,
sodium, or potassium (see the
Perspective by Isborn). The
results point to a gradual transi-
tion from the dilute electrolyte
solution of paired dielectrons to
the more delocalized metallic
structure at the highest concen-
trations. —JSY
Science, this issue p. 1086;
see also p. 1056ORGANIC CHEMISTRY
Hydrogenations that
tolerate N–O bonds
Catalysts that add hydrogen to
carbon-carbon, carbon-nitrogen,
and carbon-oxygen double bonds
are among the most widely used
in synthetic chemistry. They are
particularly adept at delivering
just one of two mirror-image
products. However, they may
also target adjacent bonds in
the compound that would be
better left intact. Mas-Roselló et
al. report that an iridium catalyst
paired with a strong acid can
hydrogenate C=N bonds without
disturbing a weak N–O bond
on the same nitrogen center.
The reactions proceed at room
temperature with high enantiose-
lectivity. —JSY
Science, this issue p. 1098NEUROSCIENCE
Making blind retinas
see again
Photoreceptor degenera-
tion is an important cause of
blindness. Nelidova et al. used
tunable, near-infrared sensors
to render diseased photorecep-
tors light sensitive again (see
the Perspective by Franke and
Vlasits). Gold nanorods capable
of detecting infrared light were
coupled with an antibody to tem-
perature-sensitive ion channels.
When the nanorods absorbed
light and converted it into heat,
the coupled ion channels were
gated by infrared light. In a
mouse model of retinal degen-
eration, these ion channels were
successfully targeted to cone
photoreceptors, and responses
to near infrared light could be
detected. In the primary visual
cortex, more cells responded
to near-infrared stimuli in mice
expressing these ion channels
than in controls. By changing the
length of the gold nanorods, the
system could be tuned to differ-
ent infrared wavelengths. —PRS
Science, this issue p. 1108;
see also p. 1057PALEOECOLOGY
Mangroves under
sea level rise
The rate of sea level rise has
doubled from 1.8 millimeters
per year over the 20th century
to ~3.4 millimeters per year
in recent years. Saintilan et al.
investigated the likely effects
of this increasing rate of rise on
coastal mangrove forest, a tropi-
cal ecosystem of key importance
for coastal protection (see the
Perspective by Lovelock). They
reviewed data on mangrove
accretion 10,000 to 7000 years
before present, when the rate
of sea level rise was even higher
than today as a result of glacial
ice melt. Their analysis sug-
gests an upper threshold of
7 millimeters per year as the
maximum rate of sea level riseEdited by Michael FunkALSO IN SCIENCE JOURNALS
RESEARCH
Published by AAAS