SCIENCE science.org 5 NOVEMBER 2021 • VOL 374 ISSUE 6568 706-B
RESEARCHEdited by Michael FunkALSO IN SCIENCE JOURNALS
CORONAVIRUS
Keeping schools
open safely
There has been considerable
debate about the role of schools
in the transmission of severe
acute respiratory syndrome
coronavirus 2 (SARS-CoV-2).
In a Perspective, Ladhani and
the sKIDs Investigation Team
discuss the data, which indicate
that although children and staff
can acquire COVID-19 in schools,
these infections largely reflect
community infection rates, and
schools are not a major driver
of transmission when mitigation
measures are in place. Those
mitigations include masking,
distancing, sanitization, air-
quality monitoring, bubbles, and
contact tracing and isolation.
Children can acquire COVID-19
and experience severe disease in
some cases, as well as extended
symptoms called Long Covid,
but children mostly benefit from
being able to attend school and
receive in-person teaching and
other support infrastructure.
—GKA
Science, abj2042, this issue p. 680
RADIOCARBON
Using carbon-14
Carbon-14, or radiocarbon, a
radioactive isotope produced in
the upper atmosphere by cosmic
rays, is rapidly incorporated into
the terrestrial carbon cycle and
provides a way to calculate the
age of carbon-bearing materials
as old as 55,000 years. Heaton
et al. review recent progress that
has allowed the construction of
better radiocarbon age calibra-
tion curves and discuss the new
insights into climate processes,
the Sun, Earth’s geodynamo,
and the carbon cycle that have
emerged from these efforts.
—HJS
Science, abd7096, this issue p. 707
MEMBRANES
Selective subatomic
separations
Membranes are thin materials
used to selectively separate
gases or liquids on a range of
scales from benchtop experi-
ments to industrial processes.
Challenges arise in separat-
ing materials with very similar
sizes or chemical properties,
particularly at the smallest
scales. Kidambi et al. review
advances in using atomically
thin two-dimensional materials
such as graphene or hexagonal
boron nitride for the separation
of subatomic species, including
electrons, hydrogen isotopes,
and gases. The authors explore
the scope to scale up the sizes
of these membranes and their
potential use in applications
relating to energy, microscopy,
and electronics. —MSL
Science, abd7687, this issue p. 708NEURODEVELOPMENT
Synapse stabilization
Early in brain development,
neurons connect to each other
enthusiastically. With develop-
ment, an overabundance of
synapses is winnowed down
to refine efficiently connected
circuits. Inactive synapses are
prime targets for elimination,
whereas active synapses tend
to be retained. Gomez-Castro
et al. took a closer look at how
these choices are made (see the
Perspective by Blum and Lopes).
When postsynaptic adenosine
receptors are muted or do not
find enough extracellular ade-
nosine, synapses get eliminated.
Neurotransmitter-dependent
signaling pathways drive protein
kinase A to phosphorylate the
postsynaptic scaffolding mol-
ecule gephyrin. Together with a
partner synaptogenic membrane
protein, gephyrin is required for
the stabilization of g-aminobu-
tyric acid receptors. Adenosine
receptors thus detect synaptic
activity and in turn drive the
stabilization of synapses thatproduce such activity. —PJH
Science, abk2055, this issue p. 709;
see also abm3902, p. 684IMMUNOLOGY
AMPlifying type 2
immunity
Antimicrobial proteins (AMPs)
are a frontline defense against
pathogenic microorganisms at
mucosal surfaces. These cat-
ionic molecules inactivate their
targets primarily by disrupting
cell walls and membranes. Hu et
al. found that small proline-rich
protein 2A (SPRR2A) is a bacte-
ricidal protein produced in the
gut that targets Gram-positive
bacteria and is phylogenetically
distinct from all other known
AMPs (see the Perspective by
Harris and Wickramasinghe).
SPRR2A production is selec-
tively enhanced by type 2
cytokines such as interleukin-4
and -13, which are elicited by
helminth infection. Mice lacking
SPRR2A are unable to prevent
intestinal bacteria from invad-
ing the intestinal barrier after
helminths damage the intestinal
epithelium. SPRR2A is thus a
critical component of type 2
immunity that protects against
the bacterial invasion and dis-
semination that follow helminth
infection. —STS
Science, abe6723, this issue p. 710;
see also abm3876, p. 682AEROSOL CHEMISTRY
Spontaneous chemistry
on aerosol surface
Interfacial redox chemistry
plays an important role in the
formation of gas molecules
and aerosol particles. However,
the characterization of such
heterogeneous processes is
challenging, so they are often
omitted in chemical kinetics
models. Using ambient-pressure
x-ray photoelectron spectros-
copy combined with molecular
dynamics simulations, Kong
et al. discovered spontaneousredox chemistry promoted by
the surface at the first stages
of the solvation process on a
typical inorganic aerosol surface
of ammonium sulfate (see the
Perspective by Ruiz-Lopez).
Several unexpected species
have been identified as possible
products of a sulfate-reducing
ammonium oxidation reac-
tion, and this may help to
resolve some of the enduring
conundrums of atmospheric
chemistry. The present results
could also be useful for the
development of wastewater
treatments and other industrial
technologies. —YS
Science, abc5311, this issue p. 747
see also abl8914, p. 686ORGANIC CHEMISTRY
Asymmetric carbon
coupling at boron
The Matteson reaction produces
carbon–carbon bonds by cou-
pling halocarbons such as widely
available dichloromethane with
an alkyl substituent on boron.
Sharma et al. report asymmetric
catalysis of this reaction. Their
catalyst, derived from a chiral
thiourea, a boronic ester, and an
alkyl lithium base, appears to
accelerate a chloride abstraction
step through its lithium center.
The product, still bearing a
chloride, can be further modified
through stereospecific displace-
ment to generate a wide variety
of trisubstituted chiral centers.
—JSY
Science, abm0386, this issue p. 752ORGANIC CHEMISTRY
Careful choreography
for a ketone shift
Chemists devote tremendous
effort to the precise place-
ment of oxygens in molecular
frameworks. Wu et al. report
a convenient method to shift
the oxygen in a carbonyl group
to an adjacent carbon center.
After activation of the oxygen to
an alkenyl triflate, cooperative