593-B 6 MAY 2022 • VOL 376 ISSUE 6593 science.org SCIENCERESEARCHCORONAVIRUS
Omicron and
reinfection risk
So far, our experience with
pandemic coronavirus has
been that the emergence of
new variants is not detected
until there has been substantial
community transmission. Early
in November 2021, South African
scientists spotted reinfections
consistent with the timing of the
emergence of the Omicron vari-
ant (B.1.1.529). In a population
largely untouched by vaccines
but widely infected, Pulliam
et al. found that Beta or Delta
variants rarely caused reinfec-
tion. However, after 31 October
2021, individuals were found
who had had three experiences
of infection (see the Perspective
by Zelner and Eisenberg). The
culprit was the rapidly emerging
Omicron variant, with multiple
mutations in the Spike protein.
This variant’s chief advantage
is its ability to evade naturally
acquired immunity. Fortunately,
the Omicron variant does not
fully evade vaccine-derived
immunity, but only those privi-
leged to have been vaccinated
can benefit. —CA
Science, abn4947, this issue p. 596;
see also abp9498, p. 579PHYSIOLOGY
Understanding
heat-induced necrosis
Z-DNA binding protein 1 (ZBP1),
a sensor for Z–nucleic acids, is
implicated in necrosis caused
by heat stress in the worm
Caenorhabditis elegans. Yuan et
al. examined the roles of proteins
that regulate necrosis in worms
undergoing heat stroke. The pro-
tein kinase receptor-interacting
protein kinase 3 (RIPK3) led
to activation of mixed lineage
kinase domain-like (MLKL) and
Caspase-8, and all were required
for heat-induced death. ZBP1 is
a RIPK3 and necrosis activator
and it appeared to contribute
to heat-induced necrosis in theworms. This response did not
require the nucleic acid–sensing
domain of ZBP1. Transcription
of ZBP1 was enhanced by heat
shock transcription factor 1
(HSF1). —LBR
Science, abg5251, this issue p.609CATA LYS I S
Peroxide as needed
Hydrogen peroxide for com-
mercial applications is currently
mass produced through an
indirect process that involves
reduction and reoxidation of a
quinone. The trouble with mak-
ing it straight from the elements
is that concentrated mixtures
of hydrogen and oxygen are
dangerously explosive. Lewis et
al. report that direct peroxide
synthesis at safe concentrations
is compatible with a current
industrial method for produc-
ing cyclohexanone oxime, a key
precursor to nylon. The protocol
could potentially offer substan-
tial efficiency advantages for
manufacturing a high-volume
bulk chemical. —JSY
Science, abl4822, this issue p. 615QUANTUM OPTICS
A quantum frequency
converter
Practical quantum tech-
nologies require interfacing of
several subsystems operat-
ing in widely different spectral
regions. However, most current
approaches offer only very
small frequency shifts and
limited tunability. Tyumenev et
al. demonstrate efficient (up to
70%) quantum state–preserving
photon frequency up-conversion
by molecular modulation in
hydrogen gas–filled antiresonant
photonic crystal fibers (see
the Perspective by Sokolov).
By combining a high-intensity
coherent pump pulse with a
(low-intensity) quantum source
based on parametric down-
conversion (generating pairs
of signal and idler photons),
the authors show that the idlerphotons could be up-converted
by 125 terahertz using a
Raman-scattering process. The
process is general and should
be applicable to other quantum
sources. —ISO
Science, abn1434, this issue p. 621;
see also abo2358, p. 575ICE SHEETS
The deeper story
Shallow, dynamic subglacial
water systems provide lubri-
cation that facilitates the
movement of overlying ice. But
are these thin layers the whole
story? Gustafson et al. show
that the subglacial sediments
beneath Whillans Ice Stream in
West Antarctica are saturated
with a mixture of fossil seawa-
ter and freshwater from the
glacier (see the Perspective
by Chu). This groundwater,
extending downward for more
than a kilometer, contains more
than 10 times as much fluid
volume as the shallow hydro-
logic system above and actively
exchanges with it. Therefore, it
has the potential to modulate
ice streaming and subglacial
biogeochemical reactions. —HJS
Science, abm3301, this issue p. 640;
see also abo1266, p. 577CONSERVATION
Population size
and risk of extinction
The vaquita porpoise is one of
the most endangered ani-
mals in the world, with only
an estimated 10 individuals
remaining. To determine the
risk of extinction caused by
inbreeding depression, Robinson
et al. sequenced and examined
20 vaquita genomes to deter-
mine their heterozygosity and
ancestral population size (see
the Perspective by Grueber
and Sunnucks). The authors
determined that the long-term
population size of vaquitas has
been low for a marine mam-
mal, with approximately
1000 years of stable genomicdiversity. Genomic comparisons
with other cetacean species
and modeling indicated that
vaquitas are unlikely to suffer
from inbreeding depression.
Therefore, if the risk of bycatch
mortality caused by fishermen
can be eliminated, then there is a
chance that this species will not
go extinct. —LMZ
Science, abm1742, this issue p. 635;
see also abp9874, p. 574ECOTOXICOLOGY
Sunscreen turned toxic
Coral reefs face many serious
threats from human activity.
Sunscreens can cause reef
damage, and although the
precise mechanisms involved
are still under study, some
localities have already phased
out common components such
as oxybenzone. Using a sea
anemone as a model system,
Vuckovic et al. found that
oxybenzone is modified within
cells by attachment of glucose,
turning it from a sunscreen into
a potent photosensitizer (see
the Perspective by Hansel). The
glycoside conjugate is concen-
trated within the algal symbionts
of anemones and corals, and
bleached anemones are more
susceptible to damage when
exposed to ultraviolet light and
oxybenzone, suggesting that the
algae provide some protection to
their hosts. These experiments
add to our understanding of reef
damage by sunscreens and may
help to inform policy and new
sunscreen development. —MAF
Science, abn2600, this issue p. 644;
see also abo4627, p. 578FERROELECTRICS
Ultrathin
ferroelectric films
The electrical properties of
ferroelectrics can be changed
with an electric field, making
them attractive materials for
computer hardware applica-
tions. Cheema et al. show that
extremely thin films of zirconiumEdited by Michael FunkALSO IN SCIENCE JOURNALS
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