Science - USA (2021-07-09)

SCIENCE sciencemag.org 9 JULY 2021 • VOL 373 ISSUE 6551 175

INFECTIOUS DISEASE

Anti-infection

immunotherapy

Antibiotic-resistant bacteria

such as methicillin-resistant

Staphylococcus aureus (MRSA)

are increasingly prevalent and

difficult to treat. Alphonse et al.

found that a pan-caspase inhibi-

tor called Q-VD-OPH functioned

as an effective immunotherapy

in mouse models of community-

acquired MRSA, Streptococcus

pyogenes, and Pseudomonas

aeruginosa skin infections. This

inhibitor reduced apoptosis

in neutrophils and monocytes

and increased necroptosis in

macrophages, thereby increasing

tumor necrosis factor production

and infection clearance in mice.

This work suggests a potential

strategy to target bacterial

infections without the use of

antibiotics. —CAC

Sci. Transl. Med. 13 , eabe9887 (2021).

MARTIAN GEOLOGY

Modified clay minerals

on Mars

Sedimentary rocks exposed

in Gale crater on Mars contain

extensive clay minerals. Bristow

et al. analyzed drill samples col-

lected by the Curiosity rover as it

climbed up sedimentary layers in

the crater. They found evidence

of past reactions with liquid

water and sulfate brines, which

could have percolated through

the clay from an overlying sulfate

deposit. Similar sulfate deposits

are widespread across the planet

and represent some of the last

sedimentary rocks to form before

the planet lost its surface liquid

water, so the results inform our

understanding of the geologic

processes that occurred as Mars

dried out. —KTS

Science, abg5449, this issue p. 198

GEOMORPHOLOGY

The limits of

channel offset

The offset of stream channels

across a strike-slip fault offer a

record of long-term slip rates.

The process itself is an interest-

ing case of landscape evolution

because the streams will spill

straight across the fault at

some point and reset the offset.

Dascher-Cousineau et al.

developed a model for this

process that they validated using

observations from the Carrizo

Plain in California. The model

leverages transitions from active

to abandoned stream channels to

determine when and how drain-

age networks in these regions

reorganize and allow quantifica-

tion of both slip and bedload

transport. —BG

Science, abf2320, this issue p. 204

MECHANOCHEMISTRY

Shear selectivity

Chemical reactions typically

proceed by distributing energy

statistically among all accessible

molecular vibrations. Liu et al.

report that external shear forces

can sometimes pry open strained

carbon rings without dissipating

PHYSIOLOGY

Keeping warm when small

S

everal mammal species live in cold-water environments,

enabled by adaptations such as blubber and large size. A

notable exception to this rule is the sea otter, a species that

is orders of magnitude smaller and skinnier than the others.

It is known that the sea otter’s unusually thick fur helps,

but Wright et al. show that they are also internally warmed by

thermogenic leak from skeletal muscle, a process that elevates

their metabolic rate three times above that expected for their size.

This mechanism is present even in infants with immature muscles,

providing these animals with internal warmth from birth. —SNV

Science, abf4557, this issue p. 223

RESEARCH

Edited by Michael Funk

IN SCIENCE JOURNALS

Sea otters use thick fur and thermogenic

uncoupling in skeletal muscle mitochondria

to stay warm in cold waters.

PHOTO: MICHAEL QUINTON/MINDEN PICTURES

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