SCIENCE sciencemag.org 6 DECEMBER 2019 • VOL 366 ISSUE 6470 1209RESEARCH
Spectroscopic dissection
of electron-phonon coupling
Na et al.,p. 1231Edited by Stella HurtleyIN SCIENCE JOURNALS
CONSERVATION ECOLOGY
Vulnerability to
habitat fragmentation
Habitat fragmentation caused
by human activities has con-
sequences for the distribution
and movement of organisms.
Betts et al. present a global
analysis of how exposure to hab-
itat fragmentation affects thecomposition of ecological com-
munities (see the Perspective by
Hargreaves). In a dataset con-
sisting of 4489 animal species,
regions that historically experi-
enced little disturbance tended
to harbor a higher proportion of
species vulnerable to fragmenta-
tion. Species in more frequently
disturbed regions were more
resilient. High-latitude areashistorically experienced more
disturbance and harbor more
resilient species, which suggests
that extinction has removed
fragmentation-sensitive species.
Thus, conservation efforts to
limit fragmentation are particu-
larly important in the tropics.
—AMS
Science, this issue p. 1236;
see also p. 1196B I O CATA LYS I S
Maximal efficiency from
enzyme cascades
Enzymes are highly selective
catalysts that can be useful
for specific transformations in
organic synthesis. Huffman et al.
combined designer enzymes in
a multistep cascade reaction
(see the Perspective by O’Reilly
and Ryan). The approach
eliminates purification steps,
recycles expensive cofactors,
and couples favorable and
unfavorable reactions. With the
target molecule islatravir, an
experimental HIV drug, they
optimized five enzymes by
directed evolution to be compat-
ible with unnatural substrates
and stable in the reaction condi-
tions. Stereochemical purity was
amplified at every enzymatic
step, and the final synthesis
was both atom economical and
efficient. —MAF
Science, this issue p. 1255;
see also p. 1199MESOSCOPIC PHYSICS
Transmitting
quantum states
The coherence of electrons in
mesoscopic structures is thought
to be unlikely to survive in a
disordered environment. Duprez
et al. show that this is not neces-
sarily the case. They studied a
metallic island as an example of
a disordered environment. They
made an electron interferometer
and incorporated the island in
one of the two paths through the
interferometer. At sufficiently low
temperatures and in the quantum
Hall regime, they observed a clear
interference pattern, indicating
successful transmission of then
lingImmunofluorescence
imaging of lymphatics
associated with hair
follicles in mouse skinCREDITS (FROM TOP): NA
ET AL.
; E. FUCHS AND S. GUR-CHOEN/THE ROCKEFELLER UNIVERSITY
STEM CELLSStem cells reshape a lymphatic niche
A
dult stem cells can both self-renew and regenerate new tissue upon demand. They reside in
microenvironments (niches) that balance these decisions to avoid tissue overgrowth, cancer,
and aging. Using murine skin as a model, Gur-Cohen et al. uncovered a lymphatic network of
capillaries associated with the stem cell niche of hair follicles (see the Perspective by Harvey).
Stem cells reshaped their lymphatic environment by switching their secretome to coordinate
lymphatic-niche association. During tissue regeneration, a dynamic change in epithelial-lymphatic
communication remodeled this association, synchronizing stem cell and niche behavior. —BAP
Science, this issue p. 1218; see also p. 1193Published by AAAS