Science - USA (2021-07-09)

SCIENCE sciencemag.org 9 JULY 2021 • VOL 373 ISSUE 6551 177

separation into different paths,

and controlled interference as

the single photons are brought

back together again. The results

provide a route for developing

complex optical quantum circuits

for on-chip quantum information

processing. —ISO

Phys. Rev. Lett. 126 , 230503 (2021).

MAGNETISM

A dilute 2D magnet

Recently discovered two-

dimensional (2D) van der Waals

magnets exhibit a number of

appealing properties, such as

a large magnetoresistance.

Most of these materials,

however, need to be cooled to

below room temperature to

exhibit these properties and

are sensitive to environmental

conditions. To address these

issues, Chen et al. exploited

an old idea, doping an oxide

with magnetic atoms, but

this time in 2D rather than

3D. The researchers used

graphitic zinc oxide, a layered

compound in which zinc and

oxygen atoms are arranged in

a hexagonal pattern, and sub-

stituted some zinc atoms with

cobalt. The samples exhibited

ferromagnetism down to

monolayer thickness, even at

room temperature. Extrinsic

mechanisms for magnetism

were excluded with careful

characterization and control

experiments. —JS

Nat. Commun. 12 , 3952 (2021).

NEUROSCIENCE

Breathing in the brain

The effect of respiration on

brain activity is much dis-

cussed. Neuronal activity

is fundamentally rhythmic,

so are breathing rhythms

entrained by typical neuronal

oscillation patterns? Tort et al.

hypothesized that breathing

frequency aids the integration

of widespread information simi-

lar to the proposed function of

other slow-network rhythms in

visual or tactile environmental

sampling. Systematic analysis

revealed strong correlations

between instantaneous breath-

ing frequency and the amplitude

and frequency of theta and

gamma oscillations. Changes in

theta activity preceded changes

in breathing frequency, which in

turn preceded changes in slow-

gamma oscillations. —PRS

J. Neurosci. 41 , 5229 (2021).

RESTORATION ECOLOGY

Seeds of success

This year marks the start of

the United Nations’ Decade

of Ecological Restoration.

Restoration of damaged habi-

tats to a self-sustaining state

(which may not necessarily be

identical to their original state)

requires close collaboration

between ecologists and land

managers. Leger et al. describe

practical aspects of such a

partnership in the restoration

of degraded grassland habitats

in the Great Basin region of

the United States. The authors

compared the restoration

potential of seeds of grass

species sourced from remnant

native habitat with seeds from

commercial sources. The wild-

collected seeds showed more

promising performance, as

measured by phenotypic traits.

In turn, these seeds can be

selected for enhanced agro-

nomic production, increasing

the supply available for more

effective restoration. —AMS

Restor. Ecol. 29 , e13260 (2021).

SYMBIOSIS

Costly symbiont

inheritance

Long-established microbial

symbioses tend toward genome

erosion and increasing host

dependence. Some relation-

ships are so pivotal to host

survival that maintaining a

stable partnership is crucial.

Koga et al. have investigated the

stable inheritance of an insect

bacterial gut symbiont called

Ishikawaella between genera-

tions of its Plataspidae stinkbug

hosts. Ishikawaella has a highly

reduced genome yet provides

essential amino acids for the

bug. The bugs lay eggs in rows

on plants, and capsules hold-

ing symbionts are deposited

among the eggs. The capsule

also contains a combination of

a specialist insect protein the

authors identified as poste-

rior midgut dominant protein

(PMDP) and a symbiont-derived

chaperone molecule, GroEL.

Together, these molecules pro-

tect the delicate Ishikawaella for

the 7 to 10 days it takes for the

eggs to hatch, at which point

the young bugs feed on the

capsule to obtain the vital sym-

bionts. However, the production

of PMDP shortens the life of the

female bugs, which is the price a

mother pays to ensure inheri-

tance. —CA

Proc. Natl. Acad. Sci. U.S.A. 118 ,

e2103957118 (2021).

Satellite view of the East

Troublesome Fire in Grand County,

Colorado, on 20 October 2020

WILDFIRES

Fired up

C

limate warming has sub-

stantially increased wildfire

activity in the western

United States, particularly

during the first two decades

of the 21st century. Higuera et

al. illustrate how destructive this

trend has become by using a

2000-year-long record of wild-

fires in the subalpine forests of

the Rocky Mountains. Their data

show that these forests now are

burning more than at any point

in the past 2000 years, capped

by the extreme fire season of

2020. The current trajectory of
      climate means that this situation
      may be expected only to worsen,
      with unprecedented rates of
      burning projected in many
      western forests by midcentury.
      —HJS
      Proc. Natl. Acad. Sci. U.S.A. 118 ,
      e2103135118 (2021).

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