Science - USA (2022-03-04)

IMAGE: GUPTA

ET AL.

SCIENCE science.org 4 MARCH 2022 • VOL 375 ISSUE 6584 987

rules affecting transcription,

resulting in predictable changes

within the genome. —LMZ

Science, abg0162, this issue p. 1000

TOPOLOGICAL PHYSICS

A monopole set

in diamond

Magnetic monopoles, hypo-

thetical sources of magnetic

field in three-dimensional

space, have not been observed

as elementary particles.

However, synthetic monopoles

can be engineered in ultra-

cold systems. Going a step

further, Chen et al. used the

quantum levels of a nitrogen

vacancy center in diamond

to observe the effects of a

synthetic tensor monopole: the

generalization of the magnetic

monopole to four dimensions.

The researchers modulated

an applied microwave pulse to

measure the “magnetic” field

emanating from the tensor

monopole and its topological

charge. —JS

Science, abe6437, this issue p. 1017

MOLECULAR KNOTS

Opportune mismatches

The typical approach to mak-

ing molecular knots is to use

metal ions to orient ligand

strands in mutually overlapping

arrangements. Ashbridge et

al. added a Vernier templating

technique to expand the size

and complexity of accessible

knots. Specifically, they intro-

duced a mismatch between the

numbers of coordination sites

on the ligands and on the metal

ions, resulting in an assembly

comprising the lowest common

multiple of sites. A 3:4 stoichi-

ometry produced a 378-atom

trefoil-of-trefoils after ring

closure by olefin metathesis.

—JSY

Science, abm9247, this issue p. 1035

EPIGENETICS

Safeguarding stem cells

Bivalent genes co-occupied by

the epigenetic markers histone

3 trimethyllysine 4 (H3K4me3)

and 27 (H3K27me3) were first

SYNTHETIC GENOMICS

Predicting effects from

genomic changes

Genetic modifications of

organisms can create artifi-

cial, synthetic genomes. Such

changes are forecast to be useful

for understanding the principles

of how genomic context affects

cellular function. However, the

effects of most drastic genomic

movements are unknown, never

having been observed in nature.

Brooks et al. examined a line of

yeast that are easily induced to

move genes within the genome

to determine how the context of

genes affects their expression.

Examining 612 genetic changes,

the authors found differences

in the length and content of

transcripts, which indicates that

the local genetic environment is

important for transcription. From

these experiments, the authors

were able to determine specific

RESEARCH

Edited by

Michael Funk

IN SCIENCE JOURNALS

KIDNEY DISEASE

Fingering FANCD2 in tubular repair

T

he transition from acute kidney injury, characterized by intrinsic repair, to incomplete

repair and chronic damage has been difficult to study. Gupta et al. modeled the transition

from intrinsic to incomplete repair using human kidney organoids. A single exposure to

cisplatin resulted in intrinsic repair, with preserved tubular architecture and up-regulation

of genes associated with homology-directed repair, including Fanconi anemia comple-

mentation group D2 (FANCD2). However, with repeated cisplatin exposure, FANCD2 and RAD51

recombinase (RAD51) were down-regulated, leading to incomplete repair. The DNA ligase IV

inhibitor SCR7 increased FANCD2-mediated repair and ameliorated progression to chronic

injury in the organoids, suggesting that targeting the FANCD2/RAD51 pathway may have the

potential to treat kidney disease. —MN Sci. Transl. Med. 14 , eabj4772 (2022).

Fluorescence microscopy image of proximal tubules in a kidney organoid that have been immunostained

to detect DNA damage markers (green)