Science - USA (2022-01-28)

400 28 JANUARY 2022 • VOL 375 ISSUE 6579 science.org SCIENCE

RESEARCH | IN OTHER JOURNALS

component called versican
promoted myelopoiesis and leu-
kocytosis. By deleting the gene
for vascular endothelial growth
factor (Vegfr2), angiogenesis
was reduced, and when IL-6 or
versican was eliminated, hema-
topoiesis slowed and myeloid
cells declined. These insights
indicate potential therapeutic
targets. —BAP
Nat. Cardiovasc. Res. 1 , 28 (2022).

MASS SPECTROMETRY

Focusing

nanoparticles in air

Intact viruses and nanopar-
ticles with masses beyond 10
megadaltons, too large to be
detectable using conventional
mass spectrometry, can be
detected with chip-based
nanomechanical resonators.

However, only a tiny fraction of

nanoparticles hit the detector,

and ion-focusing optics that can

improve their efficiency require

additional large vacuum sys-

tems. Erdogan et al. show that a

large polymer sheet around the

chip itself can act as a focus-

ing lens. Nanoparticle ions

generated at ambient pressure

through electrospray ioniza-

tion landed on the polymer. The

charged region focused the

central ion plume into the detec-

tor, leading to a greater than

100-fold increase in efficiency.

Mass spectra of gold and poly-

styrene nanoparticles, as well

as of severe acute respiratory

syndrome coronavirus 2 (SARS-

CoV-2) and bovine herpes virus

viral particles, were obtained in

this way. —PDS

ACS Nano 10.1021/

acsnano.1c08423 (2022).

SUPERNOVAE

The final months

of a dying star

When a sufficiently massive

star runs out of fuel, the core

collapses, leading to a supernova

explosion. Theory predicts that

the progenitor star can evolve

substantially in the months

before the supernova. Jacobson-

Galán et al. analyzed photometry

and spectroscopy of the super-

nova SN 2020tlf, which occurred

in September 2020. They found

a brightening of the progenitor

for about 130 days before the

explosion and an interaction of

the expanding supernova with

dense material close to the

star. The authors infer a sudden

release of energy in the star’s

core due to changing fusion

reactions, which caused the

ejection of substantial material

a few months before the star

exploded. —KTS

Astrophys. J. 924 , 15 (2022).

BIOMATERIALS

Feeling out the healing

Hydrogels have been used to

release drugs or growth factors to

help tissue repair, and the release

of different agents and concen-

trations over time can accelerate

the healing. However, the rate

of release is usually prepro-

grammed into the host matrix.

Li et al. developed a double-

network hydrogel consisting of

phenylboronic acid–cross-linked

polyvinyl alcohol (PVA) and

gelatin nanoparticles to aid in the

repair of diabetic bone defects.

The PVA network will revers-

ibly degrade upon exposure to

reactive oxygen species or high

glucose, whereas the gelatin par-

ticles were designed to respond

to certain proteinases. Therefore,

the hydrogel is able to sense and

respond to the local environment

at the wound site so that the

delivery of drugs is targeted to

each stage of the healing process.

—MSL

Ad v. M a t e r. 10.1002/

adma.202108430 (2021).

SYSTEMS BIOLOGY

Nitrogen stress patterns

Bacterial communities within

an extracellular matrix, called

biofilms, can exhibit a pattern-

forming process that resembles

the repeated patterns found in

the segmentation of animals and

plants. In such a colony, nitrogen

is more available at the edges as

the colony grows. However, Chou

et al. detected cell-autonomous

oscillations in the nitrogen stress

response that result in ring-like

patterns of cellular differen-

tiation in a colony. Because the

nitrogen stress response is linked

to sporulation, this resulted in

patterns of sporulation within the

community. Whether the bacteria

gain advantages from such mul-

ticellular behavior is unclear, but

this work provides an example of

clock-driven pattern formation

previously only ascribed to higher

organisms. —LBR

Cell 185 , 145 (2022). PHOTO: BRYANT ANDERSON/NOAA/AP IMAGES

Humpback whale entangled in

tackle used by the US Pacific

Dungeness crab fishing industry

HUMAN-WILDLIFE CONFLICT

Crabs versus whales

M

any conservation management plans are built on a narrow set of conditions that aim

to both protect species and allow exploitation of natural resources. Climate change is

likely to disrupt many of these given that it shifts the ways in which all species use their

environment. Interactions between the lucrative Dungeness crab fishery and blue and

humpback whale populations have long been managed through temporal and spatial dis-

placement. Samhouri et al. found that an extended marine heat wave during 2014–2016 in the

Northeast Pacific burned a hole in usual management practices that reduce conflict between the

crab fishery and whale migration. During the heat wave, whales shifted their movement patterns,

which led to significant increases in whale entanglement in crab fishing gear when the (already

delayed) crab fishery began. —SNV Proc. R. Soc. London Ser. B 10.1098/rspb.2021.1607 (2021).