Science - USA (2020-04-10)

150 10 APRIL 2020 • VOL 368 ISSUE 6487 sciencemag.org SCIENCE

RESEARCH | IN SCIENCE JOURNALS

they visualized dynamic activi-
ties during embryonic organ
formation, including neuro-
transmission and cell division
in the brain, autophagy in the
retina, viral gene delivery, and
placental drug transfer. They
also tracked diverging fates of
human and mouse neural crest
cells in interspecies chimeras.
—BAP
Science, this issue p. 181

SOLAR CELLS

Engineering perovskites

with anions

The bandgap of the perovskite
top layer in tandem silicon
solar cells must be tuned to
~1.7 electron volts. Usually, the
cation composition is varied
because the bromine-rich anion
compositions with wide band-
gaps are structurally unstable.
Kim et al. show that by using
phenethylammonium as a
two-dimensional additive, along
with iodine and thiocyanate,
bromine-rich perovskite films
can be stabilized. A tandem
silicon cell delivered >26%
certified power conversion effi-
ciency, and a perovskite device
maintained 80% of its initial
power conversion efficiency of

20% after 1000 hours under
illumination. —PDS
Science, this issue p. 155

TROPICAL FORESTS

Forest dynamics and

demography

Tropical forest succession
has been viewed mostly by
considering trees in categories
of early-, mid-, and late-succes-
sional species, corresponding
to a fast–slow continuum of life
history strategies. Rüger et al.
now show that the fast–slow
continuum does not capture
the demographic strategy of
the long-lived pioneer spe-
cies, an important component
of many tropical forests (see
the Perspective by Bugmann).
They developed a forest
model that allows for objective
predictions of tropical forest
dynamics and validated the

OLFACTION

Mammalian smell

sensation

Olfactory receptor (OR) genes

are the largest gene repertoire

in the mammalian genome,

representing 2 to 5% of all

protein coding among spe-

cies. Vertebrate OR genes were

thought to have intronless coding

regions, but Barnes et al. have

found that this is not always the

case. They inspected every OR

locus in the human and mouse

reference genomes, taking great

care to ensure consistency of

their annotation within and

between species. For each OR

gene, the structural features, as

well as protein conservation, were

considered to determine protein-

coding potential and to define

the coding sequence. Thirteen

human and 41 mouse OR genes

contained an intact coding

sequence split across two exons,

several of which were previously

considered to be pseudogenes.

—PRS

BMC Genomics 21 , 196 (2020).

NANOPORE MATERIALS

Anion gating of

hydrophobic nanopores

Hydrophobic nanopores can con-

trol ion currents when subjecting

them to external stimuli to induce

model’s predictions against

independent data. These

findings should advance our

understanding of tropical

forest dynamics and facilitate

sustainable tropical forest

management. —AMS

Science, this issue p. 165;

see also p. 128

T CELLS

The skinny on

T cell fatty acid uptake

When T cells take up residence

in a tissue, adaptation to that

tissue is key for their survival.

Frizzell et al. studied metabolic

adaptation of tissue-resident

memory T (TRM) cells at three

different sites: skin, liver, and

small intestine. They found that

TRM cells in each kind of tissue

rely on distinct members of

the fatty acid–binding protein

(FABP) family of proteins for

uptake of fatty acids. By trans-

ferring liver-resident TRM cells

into naïve mice, they found

that FABP expression of these

TRM cells was reprogrammed

by the tissue they ended up

seeding in the recipient mice.

This study reinforces the idea

that immune cells are integral

components of the tissues in

which they reside. —AB

Sci. Immunol. 5 , eaay9283 (2020).

BIOENGINEERING

Acellular advantage

Cell therapy for cardiac

remodeling after myocardial

infarction is therapeutic in part

owing to paracrine effects.

Capitalizing on this feature of

heart tissue regeneration,

K. Huang et al. created acel-

lular cardiac patches from

decellularized myocardium

and encapsulated factors

secreted from human cardiac

stromal cells. Patches retained

potency after cryopreservation

and improved cardiac func-

tion, reduced infarct size, and

increased angiogenesis when

applied to rat and pig hearts

after myocardial infarction.

—CC

Sci. Transl. Med. 12 , eaat9683

(2020).

Porous ellipsoidal a-Fe 2 O 3 nanoparticles made by high-temperature

calcination of b-FeOOH in the presence of polyacrylic acid

Edited by Caroline Ash

and Jesse Smith

IN OTHER JOURNALS

NANOMATERIAL

A hot way to change shape

H

eating cycles are used to transform nanomaterials,

but this can often cause shape deformation or particle

aggregation. Li et al. show that the addition of strong

capping ligands—in this case, polyacrylic acid—can

stabilize shapes or help to control final properties during

the calcination of b-FeOOH ellipsoidal particles. When heated

in air at temperatures of ~350°C, the particles transformed

into porous a- Fe 2 O 3 of similar shape and size, which then

could be reduced to form magnetic Fe 3 O 4 particles. The

authors also demonstrated that the strong ligand technique

worked with b-FeOOH nanorods, Prussian blue nanocubes,

cobalt hydroxide nanoplates, and Ni(OH) 2 nanoplates. —MSL

Chem. Mater. 10.1021/acs.chemmater.0c00573 (2020).

CREDIT: B. LI

ET AL.

, CHEM. MATER.

10.1021/ACS.CHEMMATER.0C00573 (2020)