1065-B 3 JUNE 2022 • VOL 376 ISSUE 6597 science.org SCIENCE
RESEARCH
Edited by Michael FunkALSO IN SCIENCE JOURNALS
DEVICE TECHNOLOGY
Putting memristors
to work
Memristors, resistors that
change conductivity and act as
memories, are not only being
used in commercial comput-
ing but also have several
applications in computing and
communications. Lanza et al.
reviewed how devices such as
phase-change memories, resis-
tive random-access memories,
and magnetoresistive random-
access memories are being
integrated into silicon electron-
ics. Memristors also are finding
use in artificial intelligence when
integrated in three-dimensional
crossbar arrays for low-power,
non–von Neuman architectures.
Other applications include ran-
dom-number generation for data
encryption and radiofrequency
switches for mobile communica-
tions. —PDS
Science, abj9979, this issue p. 1066
PALEONTOLOGY
Fierce fighters
Since Darwin’s time, giraffes
have been held up as a classic
example of adaptive evolution.
The fact that they browse high
in the canopy due to their long
necks has been considered a
direct result of selection for this
form of foraging. Wang et al.
describe a new Miocene giraffoid
species with helmet-like head-
gear and complex head and neck
joints indicative of intense head-
butting combat. They argue
that selection for such combat
also played a role in shaping the
group’s long necks. —SNV
Science, abl8316, this issue p. 1067
MICROBIOLOGY
Strain-specific single-cell
sequencing
Single-cell methods are the
state of the art in biological
research. Zheng et al. developed
a high-throughput technique
called Microbe-seq designed
to analyze single bacterial cells
from a microbiota. Microbe-seq
uses microfluidics to separate
individual bacterial cells within
droplets and then extract,
amplify, and barcode their
DNA, which is then subjected
to pooled Illumina sequencing.
The technique was tested by
sequencing multiple human fecal
samples to generate barcoded
reads for thousands of single
amplified genomes (SAGs) per
sample. Pooling the SAGs cor-
responding to the same bacterial
species allowed consensus
assemblies of these genomes
to provide insights into strain-
level diversity. It also revealed a
phage association and limits on
horizontal gene-transfer events
between strains. —CA
Science, abm1483, this issue p. 1068I M M U N O L O GY
An expansive view
of immunity’s start
Although recent single-cell
genomics studies have offered
profound insights into the devel-
oping human immune system,
they have not conceptualized
the immune system as a dis-
tributed network across many
tissues. Suo et al. integrated
single-cell RNA sequencing,
antigen-receptor sequencing,
and spatial transcriptomics of
nine prenatal tissues to recon-
struct the immune system’s
development through time
and space. They describe late
acquisition of immune effector
functions by macrophages and
natural killer cells and the matu-
ration of monocytes and T cells
before peripheral tissue seed-
ing. Moreover, they describe
how blood and immune cell
development occurs, not just in
primary hematopoietic organs,
but across peripheral tissues.
Finally, the authors character-
ize the development of various
prenatal innate-like B and T cell
populations, including B1 cells.
—STS
Science, abo0510, this issue p. 1069BIOCHEMISTRY
Hijacking tRNAs to halt
protein synthesis
Molecules that derail translation
can be useful tools and drugs,
but they are also likely to be toxic
unless they are highly specific
for a desired target. Xie et al.
found that adenosine sulfamate
can react to form mimics of
adenylates, which are common
biosynthetic intermediates in
condensation reactions (see
the Perspective by Statsyuk).
Screening a panel of sulfamates,
the authors found a molecule
with a modified base, ML901,
that inhibited the growth of the
malaria parasite Plasmodium
falciparum in vitro and in animals
but was not toxic to human cells.
A key enzyme in protein biosyn-
thesis, tyrosine–transfer RNA
(tyrosine-tRNA) synthetase,
binds ML901 and attaches it to
tyrosine from a tyrosine-tRNA,
producing a dead-end product
that blocks the active site and
inhibits downstream protein syn-
thesis in the parasite. Toxicity of
ML901 for the parasite is specific
because the human enzyme is
unable to catalyze this reaction.
—MAF
Science, abn0611, this issue p. 1071;
see also abq4457, p. 1049CONSERVATION
Ending biodiversity loss
Land conversion is one of the
biggest threats to biodiversity in
the modern world. In two related
papers, the amount of uncon-
verted land and the degree of
connectivity among landscapes
were measured, painting a clear
picture of both what needs to
be protected and the urgency of
this task (see the Perspective by
McGuire and Shipley). Allan et
al. found that 44% of terrestrial
land must be ecologically sound
to prevent major biodiversity
losses. Brennan et al. found that
the most important connectivity
routes among protected areas
remain threatened by conver-
sion. In both cases, the authorsemphasize that much of the
needed area is occupied by
human populations, emphasiz-
ing the importance of improving
sustainable cohabitation and
ecosystem protection in these
regions. —SNV
Science, abl9127, abl8974,
this issue p. 1094, this issue p. 1101;
see also abq0788, p. 1048MEMBRANES
Polymer membranes for
crude oil separation
Organic and aprotic solvents
will typically destroy polymer
separation membranes, thus
making it difficult to separate
organics by this route. Chisca
et al. synthesized polytriazole
membranes through film cast-
ing and non-solvent-induced
phase separation, followed by a
simple thermal treatment step
to induce chemical cross-linking
(see the Perspective by Seo
and Koh). This converted the
polymer into an asymmetric
membrane with an ~10-nm
selective layer showing excel-
lent solvent permeability and
selectivity. The membranes can
enhance the concentration of
hydrocarbons with fewer than
10 carbons and were also used
for the fractionation of crude
oil. —MSL
Science, abm7686, this issue p. 1105;
see also abq3186, p. 1053ECOTOXICOLOGY
Nonlethal effects matter
Glyphosate is one of the most
widely used herbicides globally,
with broad usage in both home
and agricultural settings. Debate
is ongoing as to whether this
chemical threatens vertebrates,
including humans. However, the
nontarget organisms with the
greatest exposure are insects,
a group that is both essen-
tial and seemingly in decline.
Weidenmüller et al. looked
at the impacts of glyphosate
on bumblebees, which are
essential pollinators, and found