Science_-_6_March_2020

SCIENCE sciencemag.org 6 MARCH 2020 • VOL 367 ISSUE 6482 1087

Edited by Caroline Ash

and Jesse Smith

IN OTHER JOURNALS

ORGANIC CHEMISTRY

Sulfurous glue for

heterocycles

Palladium catalysts can stitch

together a wide variety of carbon-

based aromatic rings, but they

often get hung up if both rings

contain nitrogen. Qin et al. report

that a sulfur reagent can help fill

this gap. Specifically, they show

that isopropyl sulfinyl chloride

can react successively with two

Grignard-activated heterocycles,

such as pyridine rings, and then

couple them together by elimina-

tion. The reaction was compatible

with a wide variety of five- and

PHOTOSYNTHESIS

Bulky lipids for light-harvesting control

L

ipid membranes are extraordinarily complex, with many

different acyl chains, head groups, and proteins contributing

to their shape, curvature, and fluidity. In membranes with

specialized functions, such as the thylakoid membranes

within chloroplasts, these properties can influence the func-

tion of the embedded membrane proteins. Tietz et al. measured

changes in the behavior of proteoliposome-reconstituted light-

harvesting complex II, a protein that normally gathers light for

photosystem II, in the presence or absence of the non–bilayer-

forming lipid monogalactosyldiacylglycerol. In this assay, the

lipid stimulated energy quenching, which would divert light

energy into heat and be photoprotective in high-intensity light.

The authors suggest that changes in lateral membrane pressure

caused by the bulky lipids may influence pigment conformations

within the protein and thus alter the amount of light energy mov-

ing through the system. —MAF

J. Biol. Chem. 295 , 1857 (2020).

Behavioral patterns in fruit f ies, Drosophila melanogaster, vary by individual.

Model of the light-harvesting complex II trimer structure for membranes

containing only bilayer-forming lipids

Key to generating individual

diversity in the population is

the inherent chaos of normal

development. A set of neurons

in the visual system is wired up

in a variable manner, result-

ing in brain circuit asymmetry

unique to each fly that guides

its line-walking behavior. With

more asymmetry in its brain

circuit, a fly is better able to

orient to the line. —PJH

Science, this issue p. 1112

NEUROSCIENCE

Human brain activity

during memory

Animal studies suggest that

sequence replay of neuronal

activity may underlie memory

retrieval and consolidation.

However, there is no direct

evidence that the replay of

spiking activity sequences is

important for these processes

in the human brain. Vaz et

al. simultaneously recorded

single-unit spikes, local field

potential, and intracranial

electroencephalography

signals in the brain while

participants performed a

memory task. Sharp wave

ripple oscillations in the

temporal lobe cortex reflected

bursts of neural spiking,

and these bursts of spikes

organized into sequences

during memory formation.

These sequences were

replayed during successful

memory retrieval. The extent

of sequence replay during cor-

rect recall was related to the

extent to which cortical spik-

ing activity was coupled with

ripples in the medial temporal

lobe. —PRS

Science, this issue p. 1131

PHOTO: NG IMAGES/ALAMY STOCK PHOTO

5-ethynyl-uridine (EU) in single

cells (scEU-seq), which allows

estimation of RNA transcrip-

tion and degradation rates.

When examining intestinal

organoid cells, scEU-seq data

can be used to discern between

transcription and degradation

during development, indicat-

ing that this method can be

applied to better understand

the relationship between gene

expression and RNA degrada-

tion during development. —LMZ

Science, this issue p. 1151

CELL SURFACE MAPPING

Pinpointing proteins

To develop drugs that target a

specific cell surface protein, it’s

helpful to know which other pro-

teins reside in its vicinity. Geri et

al. report a light-triggered label-

ing technique that improves the

spatial resolution for this type of

mapping. Specifically, they rely

on a photocatalyst with a very

short energy-transfer range to

activate a carbene-based label

that can only diffuse a short dis-

tance in water before reacting.

They showcase the technique by

mapping the environment of the

programmed-death ligand 1 (PD-

L1) protein on B cell surfaces, a

system of considerable interest

in cancer immunotherapy. —JSY

Science, this issue p. 1091

NEURODEVELOPMENT

Diversity from

development

When given a line to follow, some

fruit flies do so carefully and

others weave. Linneweber et al.

now show that these behaviors

are stable for an individual but

diverse in an isogenic population.

Published by AAAS