Science - USA (2022-06-10)

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SCIENCE science.org 10 JUNE 2022 • VOL 376 ISSUE 6598 1179

chiral centers, and selecting just

one of the ballooning number

of diastereomers in such cases

can be daunting. In this context,

de Jesús Cruz et al. report that

product crystallization during

the reaction can supplement the

catalyst’s intrinsic selectivity.

Specifically, the authors used a

chiral base to set one stereo-

center in a Michael addition of

nitroalkanes to ketoamides while

dynamically scrambling the

configurations on the adjacent

carbons. Crystallization then

selects a single diastereomer from

this interconverting mixture. —JSY

Science, abo5048, this issue p. 1224

AGING

Timing eating and fasting

for longevity

Animals fed a limited number of

calories, just enough to avoid mal-

nutrition, show extended health

COMMUNITY ECOLOGY

More predation in

warmer seas

Species richness of many taxa

is higher near the equator, and

ecologists have long hypoth-

esized that this pattern is linked

to stronger interactions between

species (e.g., competition and

predation) in the tropics. However,

empirical evidence showing that

the strength of species interac-

tions varies with latitude is limited.

Ashton et al. tested whether

predation on benthic marine

communities is higher at lower

latitudes. Using a standardized

experiment at 36 sites along the

Pacific and Atlantic coasts of

North and South America, the

authors found both greater preda-

tion intensity (consumption rate)

and stronger impacts on benthic

communities nearer the equator.

These trends were more strongly

related to water temperature

than to latitude, suggesting that

climate warming may influence

top-down control of communi-

ties. —BEL

Science, abc4916, this issue p. 1215

MICROBIOME

Establishing early

diversity

Humans living an urbanized

lifestyle in industrialized countries

tend to have less diverse micro-

biota than people living more rural

existences. Using fecal 16S ribo-

somal RNA sequencing, Olm et al.

found that after the first 6 months

of life, the microbiome of infants

living in contrasting environments

diverged from Bifidobacteria-

dominated assemblages. Deep

metagenomic sequencing

revealed that a large proportion

of the bacterial species detected

in samples from hunter-gatherer

infants were new and were

undetectable in samples from

urbanized children. Gut micro-

biota diversity appears early in the

lives of hunter-gatherer infants

and is traceable to maternal

transmission, with some influence

from the local environment. The

main driver for differences among

gut microbiota originates in life-

style rather than geography. It is

suspected, but still enigmatic, that

such differences in microbiota

have functional implications for

the health of developing children.

—CA

Science, abj2972, this issue p. 1220

ORGANIC CHEMISTRY

Catalysis paired with

crystallization

Asymmetric catalysis often

distinguishes mirror-image

configurations at a single carbon

center. However, many complex

molecules have three or more

Corn smut fungus senses nutrients in its maize

host that trigger its reproductive cycle.

Edited by

Michael Funk

IN SCIENCE JOURNALS

RESEARCH

PLANT SCIENCE

Host plant nurtures fungus

S

ome fungi depend on their living hosts for

sustenance. The corn smut fungus Ustilag

maydis can grow independently but

depends on the host maize plant to repro-

duce. Kretschmer et al. analyzed which

host nutrients are required to support this obli-

gate biotroph’s lifestyle. The fungus responds

to a combination of nutrients, including organic

acids such as malate, which maize uses as a

substrate for C4 photosynthesis. Identification

of dicarboxylate transporters showed that the

ability of the fungus to draw these organic acid

out of the host plant contributes to the patho-

gen’s virulence. With such nutrition ensured,

the fungus can then move through its life cycle.

—PJH Science, abo2401, this issue p. 1187