Science - USA (2021-12-17)

SCIENCE science.org 17 DECEMBER 2021 • VOL 374 ISSUE 6574 1460-B

RESEARCH

SPIN CHEMISTRY

Quantum oscillations

in radical pairs

The spin dynamics of photoin-
duced radical pairs, involving an
interconversion between singlet
and triplet spin states, plays
an important role in nature, for
example, in avian magnetorecep-
tion. The spin interconversion
is a truly quantum process
with characteristic coherent
oscillations (quantum beats)
that should be reflected in the
reaction kinetics. However, their
experimental observation has
remained challenging. Mims et
al. developed an optical readout
technique that can directly
monitor the singlet-triplet
interconversion quantum beats,
as demonstrated for a photoin-
duced, charge-separated state
of an electron donor–acceptor
dyad (see the Perspective by
Hore). The present work opens
a new way to monitor the spin
evolution in radical pairs, which
will be important not only in
biological physics but also in
organic solar cells and other
practical applications. —YS
Science, abl4254, this issue p. 1470;
see also abm9261, p. 1447

PEROVSKITES

Nitrides join the

perovskite club

Perovskite structured materi-
als have a variety of uses as
photovoltaics, capacitors, and
micromechanical actuators,
along with other applications.
Oxides, halides, and chalcogen-
ides all have large numbers of
perovskite structured materials.
Examples of perovskite nitrides
are conspicuously absent, but
Ta l l e y et al. managed to synthe-
size one (see the Perspective
by Hong). Lanthanum tungsten
nitride in the perovskite structure
turns out to be piezoelectric,
which is ideal for a variety of
applications. Perovskite struc-
tured nitrides are very attractive
because they could easily

integrate with the large number

of nitride-based semiconducting

devices already in use. —BG

Science, abm3466, this issue p. 1488;

see also abm7179, p. 1445

FOREST ECOLOGY

An experimental forest

ecosystem drought

Drought is affecting many of the

world’s forested ecosystems,

but it has proved challenging

to develop an ecosystem-level

mechanistic understanding of

the ways that drought affects

carbon and water fluxes through

forest ecosystems. Werner et al.

used an experimental approach

by imposing an artificial drought

on an entire enclosed ecosys-

tem: the Biosphere 2 Tropical

Rainforest in Arizona (see the

Perspective by Eisenhauer and

Weigelt). The authors show

that ecosystem-scale plant

responses to drought depend on

distinct plant functional groups,

differing in their water-use

strategies and their position in

the forest canopy. The balance

of these plant functional groups

drives changes in carbon and

water fluxes, as well as the

release of volatile organic com-

pounds into the atmosphere.

—AMS

Science, abj6789, this issue p. 1514;

see also abn1406, p. 1442

BIOTECHNOLOGY

Reading amino acids

by nanopore

Nanopore technology enables

sensing of minute chemical

changes at the single-molecule

level by detecting differences

in an ion current as mol-

ecules are drawn through a

membrane-embedded pore.

The sensitivity is sufficient to

discriminate between nucleotide

bases in nanopore sequenc-

ing, and other applications of

this technology are promising.

Brinkerhoff et al. developed a

nanopore-based, single-molecule

approach in which a protein

was sequentially scanned in

single-amino-acid steps through

the narrow construction of a

nanopore, and ion currents were

monitored to resolve differences

in the amino acid sequence along

the peptide backbone (see the

Perspective by Bošković and

Keyser). The peptide reader was

capable of reliably detecting

single-amino-acid substitu-

tions within individual peptides.

An individual protein could be

re-read many times, yielding very

high read accuracy in variant

identification. These proof-of-

concept nanopore experiments

constitute a promising basis for

the development of a single-mol-

ecule protein sequencer. —DJ

Science, abl4381, this issue p. 1509;

see also abn0001, p. 1443

CARBON CAPTURE

A hydrophobic CO

2

physisorbent

Most materials for carbon diox-

ide (CO 2 ) capture of fossil fuel

combustion, such as amines,

rely on strong chemisorption

interactions that are highly

selective but can incur a large

energy penalty to release CO 2.

Lin et al. show that a zinc-based

metal organic framework mate-

rial can physisorb CO 2 and incurs

a lower regeneration penalty. Its

binding site at the center of the

pores precludes the formation

of hydrogen-bonding networks

between water molecules. This

durable material can prefer-

entially adsorb CO 2 at 40%

relative humidity and maintains

its performance under flue gas

conditions of 150°C. —PDS

Science, abi7281, this issue p. 1464

LIVER DISEASE

Halting a hepatocyte

lipotoxicity driver

Despite its prevalence and

seriousness, nonalcoholic

steatohepatitis (NASH) still

lacks a treatment. Zhang et

al. show that the lipoxygenase

ALOX12 increases NASH severity

in mice, pigs, and macaques

independently of its enzymatic

function by stabilizing acetyl-

CoA carboxylase 1 (ACC1),

altering lysosomal degradation,

increasing hepatocyte inflamma-

tion, and impeding ketogenesis.

In a separate study, Zhang et

al. demonstrate that a small

molecule effectively disrupts

the ALOX12-ACC1 interaction in

vivo, halting the development of

liver steatosis, inflammation, and

fibrosis in mice and macaque

models of NASH without eliciting

the hyperlipidemia that typically

results from inhibiting the more

canonical enzymatic function of

ACC1. —CAC

Sci. Transl. Med. 13 ,

eabg8116, eabg8117 (2021).

METABOLISM

Insulin resistance

from IP

3

Rs

Dysregulation of calcium

homeostasis in adipose tissue

is associated with lipid accu-

mulation and obesity. Guney

et al. investigated the role of

IP 3 Rs, ligand-gated channels

that release Ca2+ from intracel-

lular stores, in adipose tissue

inflammation during obesity.

IP 3 R levels and activity increased

in the adipose tissue of mice

fed a high-fat diet. Mice lacking

IP 3 R1/2 in adipocytes still gained

weight when fed a high-fat diet

but had reduced inflammatory

cell infiltration of adipose tissue

and did not develop some of the

adverse metabolic effects of

obesity, such as insulin resis-

tance. —WW

Sci. Signal. 14 , eabf2059 (2021).

MEDICINE

Targeting the

endocannabinoid system

The endocannabinoid sys-

tem has diverse functions

throughout the body, affecting

neural development, neuron

Edited by Michael Funk

ALSO IN SCIENCE JOURNALS