Science - USA (2022-01-21)

PHASE TRANSITION

On the nucleation of

quasicrystals

Quasicrystal structures are

solids with symmetries of their

atomic arrangements that are

forbidden for periodic crys-

tals. Despite decades of active

research on quasicrystals and

their discovery in nature, the

mechanism of quasicrystal

nucleation remains unclear.

Using high-index saddle

dynamics applied to a Landau

free-energy functional, Yin et al.

obtained an interesting picture

of critical nuclei and minimum

energy paths that could shed

light on how quasicrystals

for structural analysis and will

prove valuable in situations in

which there is rapid development

of antibody-escape variants to

known pathogens such as HIV or

SARS-CoV-2. — PAM

S c i. Ad v. 10.1126/sciadv.abk2039

(2022).

CORONAVIRUS

Veterans’ virus affairs

The US Department of Veterans

Affairs (VA) provides life-long

health care to military person-

nel, and VA data offer a unique

resource for public health surveil-

lance in the United States. Cohn

et al. examined data from over

780,000 individuals to track the

effects of vaccination rollout as

the Delta variant of severe acute

respiratory syndrome coronavirus

2 (SARS-CoV-2) emerged in the

United States between February

and September of 2021. Although

messenger RNA (mRNA) and

viral vector vaccines have

effectively prevented clinically

significant disease, SARS-CoV-2

Delta transmission has surged.

Vaccine breakthrough infections

have predominated in those given

the viral vector vaccine but also

occur among those given mRNA

vaccines. By September 2021,

the protection offered by the viral

vector vaccine during the study

declined to about 13% against

infection and to about 50%

against death. Unvaccinated indi-

viduals remained at the highest

risk of infection, severe disease,

and death. —CA

Science, abm0620, this issue p. 331

PLANT SCIENCE

Block to polyspermy

The next generation needs

enough, but not too many, nuclear

genomes. Zhong et al. show

how the small mustard plant

Edited by Caroline Ash

and Jesse Smith

IN OTHER JOURNALS

Arabidopsis both blocks poly-

spermy and adds second-chance

insurance when the first fertiliza-

tion effort goes awry. Signals from

the synergid cells in the female

gametophyte invite a nearby

pollen tube, which secretes

peptides to block other pollen

tubes from tagging along. The

blockade persists as the pollen

tube grows to its target. If the pol-

len tube successfully releases its

pair of sperm (plants have a dual

fertilization system), the pollen

tube’s signaling system fades to

silence. If the female gametophyte

successfully receives the sperm

nuclei, invitational signals from

the synergid cells also fade to

silence. If, however, fertilization

fails, the persistent signal from the

synergid cells continues to attract

pollen tubes and, because pollen

tube rupture silenced the first

pollen tube’s block to polytuby,

secondary pollen tubes are able

to give another try at fertilization.

— PJ H

Science, abl4683, this issue p. 290

CANCER

A Yes to new therapies?

Patients with hepatocellular carci-

noma (HCC) have few therapeutic

options. The transcriptional coact-

ivators YAP/TAZ are implicated

in HCC development, although

mutations in their genes are not

associated with disease. Guégan

et al. show that the activity of the

tyrosine kinase Yes upstream

of YAP/TAZ promotes HCC cell

proliferation and tumor develop-

ment in a manner dependent on

the phosphorylation and nuclear

translocation of YAP/TAZ. Data

from HCC patients showed that

increased Yes activity, rather than

mutations in Ye s or increased Yes

abundance, was correlated with

poor survival. —JFF

Sci. Signal. 15 , eabj4743 (2022).

SCIENCE science.org 21 JANUARY 2022 • VOL 375 ISSUE 6578 279

Porphyromonas gingivalis, shown here in a computer-created illustration,

associates with periodontal disease and disrupts antiviral defenses.

HOST DEFENSE

Biting into antiviral defense?

T

he oral bacterium Porphyromonas gingivalis has been

implicated in periodontal disease, and Rodriguez-

Hernandez et al. report that it can also interfere with

host antiviral responses in mice. The bacterium disrupts

interferon (IFN)-l production by oral epithelial cells

by the downregulation of IFN-activating transcription fac-

tors. Moreover, P. gingivalis promotes insensitivity to IFN

by enhancing the proteolytic degradation of IFN recep-

tors. Finally, P. gingivalis levels correlate with suppressed

IFN responses in human oral tissues. Future studies will be

needed to tease out whether P. gingivalis overabundance has

clinically relevant effects on viral infection and transmission.

—STS Proc. Natl. Acad. Sci. U.S.A. 118 , e2105170118 (2021).

Microscopy image of an Arabidopsis pistil fi lled with pollen tubes stretching from
IMAGES (LEFT TO RIGHT: ZHONGpollen grains (far right) toward individual ovules.

ET AL

.; KATERYNA KON/SCIENCE SOURCE