The generation and function of
hair follicles also requires spatial
arrangement of skin cells and
extracellular matrix, which has
been difficult to reproduce in vitro.
To address this challenge, Abaci
et al. used three-dimensional (3D)
printing technology to generate
hair follicle–like microwells in a
three-dimensionally reconstructed
dermis. This allowed them to
arrange human cells critical for
hair growth into a physiologically
relevant configuration. Grafting of
vascularized versions of these skin
constructs onto mice resulted in
the growth of human hair. —PAK
Nat. Commun. 9 , 5301 (2018).SCIENCE sciencemag.org 18 JANUARY 2019 • VOL 363 ISSUE 6424 243(C–H) bonds. The weakest among
them are easy to transform selec-
tively, but the stronger ones tend
to be hard to discriminate. Zhao
et al. report a manganese catalyst
that can selectively oxidize
CH 2 centers in the presence of
aromatic C–H bonds. The catalyst
activates hydrogen peroxide with
the help of chloroacetic acid,
and despite targeting strong
C–H bonds, it tolerates halogen,
oxygen, and nitrogen functional-
ity. The protocol is demonstrated
across a variety of pharmaceuti-
cally relevant compounds. —JSY
Nat. Chem.10.1038/s41557-018-
0175-8 (2018).BIOMEDICINE
Addressing
a hairy problem
Bioengineered skin grafts have
helped many patients who have
suffered considerable skin loss
caused by disease or injury.
However, these grafts often lack
hair follicles, which are critical
for thermoregulation, barrier
function, and wound healing.PHYSICS
Dynamics of repulsive
Fermi gases
Pump-probe techniques,
in which a short light pulse
knocks the system out of
equilibrium and another pulse
is then used to monitor the
dynamics, are commonplace
in solid-state physics. Amico
et al. used such a technique
in a fermionic atomic gas to
study what happens when the
gas is plunged into a regime
where the atoms strongly
repel one another. The nature
of this regime in an even
mixture of two spin states has
been debated—a ferromag-
netic state was expected,
but instead the atoms had a
tendency to form pairs. Here,
the researchers disentangled
the two pathways and found
that correlations consistent
with ferromagnetism initially
increased faster than the
pairs formed, but neither
clearly dominated over the
other. —JS
Phys. Rev. Lett. 121 , 253602 (2018).BIOTECHNOLOGY
Precision CRISPR editing
The most popular gene-editing
tool, CRISPR-Cas9, generates
breaks in the genome that are
subsequently repaired by a mix of
cellular pathways. Yet, the repair
outcomes are not random. Using
machine-learning algorithms to
analyze large amounts of Cas9-
mediated, genome-wide editing
events in a range of cells, Shen et
al., Allen et al., and Chakrabarti et
al. uncovered sequence deter-
minants of repair outcomes and
devised rules to predict editing
products. These findings provide
insights into the repair process
and instruct the design of guide
RNAs to achieve more precise
editing. —SYM
Nature 563 , 646 (2018).
Nat. Biotechnol. 37 , 64 (2019).
Mol. Cell 10.1016/j.molcel.2018.
11.031 (2018).ORGANIC CHEMISTRY
Targeting CH 2 sites
Most organic compounds contain
numerous carbon-hydrogen3D-printed template used to create
GRAPHIC: H. ABACI hair follicles in reconstructed dermis
ET AL.
, NAT. COMMUN.
BIOGEOGRAPHYPathogens at the limits
T
he factors controlling the geographical distribution of organisms are receiving
increasing attention in the context of climate change. Bruns et al. analyze the effects
of a different, little-studied factor—the role of disease in limiting the range of species.
In alpine plants in northwest Italy, they found that a pollinator-transmitted fungus that
causes sterilizing anther-smut infections in meadow flowers occurred throughout
the plant’s range. Reduced population densities of these plants at their range limits does not
affect the distribution of the insect-borne pathogen. Indeed, disease incidence was often
higher at the range limit, perhaps curtailing the plant’s distribution. These findings suggest
that the role of pathogens should receive more attention in biogeographical analysis. —AMS
J. Ecol. 107 , 1 (2019).
Sexually transmitted disease limits the distribution of
European alpine meadow flower populations.Published by AAAS