SCIENCE science.org 29 OCTOBER 2021 • VOL 374 ISSUE 6567 576-B
RESEARCHEdited by Michael FunkALSO IN SCIENCE JOURNALS
NEUROSCIENCE
The source of memory
Where are memories formed
and stored? The answers to this
question could have wide-rang-
ing implications. In a Perspective,
Shin et al. discuss their hypoth-
esis that layer 1 of the neocortex
is where long-term semantic
memory is formed and stored.
The pyramidal neurons that
comprise the neocortex are ide-
ally suited to this role because
there are numerous inputs
from other regions of the brain,
allowing features and context to
be programmed together in one
cell. Understanding this process,
as well as how memories are
retrieved, could be informative
for memory disorders, learning,
and even how artificial intel-
ligence networks are designed.
—GKA
Science, abk1859, this issue p. 538
IMMUNOLOGY
The clock is ticking for
senescent cells
Senescent cells promote
their own recognition and
removal through the immune
system by generating a
bioactive secretome called
the senescence-associated
secretory phenotype (SASP).
Sturmlechner et al. report
that the cell cycle regulator
p21 directs an early form of
the SASP, which they call the
p21-activated secretory pheno-
type (PASP) (see the Perspective
by Reen and Gil). As part of the
PASP, the chemokine CXCL14
attracts macrophages, which
monitor stressed cells express-
ing elevated p21. If stressed
cells recuperate and p21 levels
return to normal within 4 days,
then macrophages disengage
from their targets. Otherwise,
macrophages recruit cytotoxic
T cells that facilitate target cell
removal. Other cell cycle regula-
tors such as p16 can induce
many factors overlapping with
the PASP, but p21 uniquely drives
this CXCL14-mediated “timer”
mechanism of senescent cell
immunosurveillance. —STS
Science, abb3420, this issue p. 577;
see also abm3229, p. 534INDIGENOUS PEOPLES
Long-term impacts of
land dispossession
To date, we lack precise esti-
mates of the extent to which
Indigenous peoples in parts of
North America were dispos-
sessed of their lands and forced
to migrate by colonial settlers,
as well as how present-day tribal
lands compare to their original
lands. Farrell et al. constructed
a new dataset within the
boundaries of the current-day
United States and found that
Indigenous land density and
spread in has been reduced by
nearly 99% (see the Perspective
by Fixico). Present-day tribal
lands are more vulnerable to cli-
mate change and contain fewer
resources. Research and policy
implications of these findings are
discussed. —TSR
Science, abe4943, this issue p. 578;
see also abl6288, p. 536CORONAVIRUS
The bat connectionThe heterogeneity of COVID-19
makes it challenging to predict
the course of infection in an
individual. Upon virus infection,
interferons (IFNs) generate
the initial signals for cellular
defenses. Knowing that defects
in IFN signaling are associated
with more severe COVID-19,
Wickenhagen et al. used IFN-
stimulated gene expression
screening on human lung cells
from which they identified a
gene for 2 9 -5 9 -oligoadenylate
synthetase 1 (OAS1) (see the
Perspective by Schoggins). OAS1
stimulates RNase L to inhibit the
virus with a surprising degree
of specificity, targeting the
membranous organelles in which
it replicates. In most mammals,OAS1 is attached to membranes
by a prenyl group. However,
billions of humans do not have
the prenylated OAS1 haplotype,
including many experiencing
severe COVID-19. The same is
true for horseshoe bats, prolific
sources of betacoronaviruses,
because of an ancient ret-
rotransposition event. —CA
Science, abj3624, this issue p. 579;
see also abm3921, p. 535POLYMER CHEMISTRY
Polyethylene with a
nickel’s worth of CO
The biggest problem with poly-
ethylene, the most abundantly
manufactured plastic, is that it
doesn’t break down easily once it
is discarded. Chemists have long
sought to introduce small quan-
tities of carbon monoxide (CO)
into polyethylene chains to pro-
mote photodegradation, but too
much CO tends to jump in and
spoil the plastic’s other proper-
ties. Baur et al. report that nickel
catalysts coordinated by bulky
phosphinophenolate ligands
can catalyze ethylene polymer-
ization with approximately 1%
CO incorporation, preserving
tensile strength while promoting
degradation under ultraviolet
exposure (see the Perspective by
Sobkowicz). —JSY
Science, abi8183, this issue p. 604;
see also abm2306, p. 540SUPERCONDUCTIVITY
Measuring the effective
charge
At low enough temperatures,
superconductors are capable of
conducting electricity without
any resistance because of the
formation of so-called Cooper
pairs of electrons. Cooper pairs
typically form at the same
critical temperature at which
superconductivity sets in. In cer-
tain materials, they are thought
to form above that tempera-
ture, but showing this property
directly in an experiment istricky. Bastiaans et al. used
tunneling noise spectroscopy to
measure the effective charge of
current carriers in the disordered
superconductor titanium nitride.
As expected, below the criti-
cal temperature, the effective
charge was equal to two electron
charges. However, this behavior
persisted above the critical tem-
perature, indicating that electron
pairs exist in that regime. —JS
Science, abe3987, this issue p. 608PLASMONICS
Switching a polymer
Electrically switchable metasur-
faces and plasmonic materials
will enable the development of
active nanophotonic technol-
ogy. Karst et al. show that a
metallic polymer can be used for
electrical switching of plasmonic
nanoantenna resonances. The
plasmonic resonance can be
completely switched ON and
OFF with switching speeds up
to 30 hertz (video rate), low
switching voltages of ±1 volt
(complementary metal-oxide
semiconductor compatible),
and a transmission modulation
depth of 100%. The results could
have applications in nanopho-
tonic devices such as those used
in augmented and virtual reality
imaging applications. —ISO
Science, abj3433, this issue p. 612SKIN INFLAMMATION
IL-12 curtails cutaneous
inflammation
Psoriasis is primarily a type
3 immune response–driven
pathology, motivating the
development of interleukin-23
(IL-23)–neutralizing therapies.
Despite the initial clinical suc-
cess of monoclonal antibodies
targeting the shared IL-12/
IL-23 p40 subunit, the supe-
rior efficacy of IL-23–specific
antibodies suggests that sparing
IL-12 is beneficial. To investigate
the cell-type-specific role of
IL-12 signaling during pso-
riasiform inflammation, Zwicky