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)