SCIENCE sciencemag.org 2 OCTOBER 2020 • VOL 370 ISSUE 6512 71PHOTO: MANAN VATSYAYANA/GETTY IMAGES
obtained a very large heat flux
using only solid materials and
a cooling fan to remove heat
from their device. Torello et al.
used fluids for heat transfer,
leading to a very large temper-
ature difference between the
hot side and the cold side. The
new designs demonstrate the
potential for devices that might
be competitive with vapor com-
pression–based appliances
with further optimization. —BG
Science, this issue p. 129, p. 125SOLAR CELLS
Relieving
unwanted strain
Although the a-phase of
formamidinium lead iodide
(FAPbI 3 ) has a suitable bandgap
for use in solar cells, it must be
stabilized with additional cat-
ions. These compositions can
adversely affect the bandgap
and produce lattice strain that
creates trap sites for charge
carriers. Kim et al. found that
substituting small, equimo-
lar amounts of cesium and
methylenediammonium cations
for formamidinium reduced the
lattice strain and trap densities.
The enhancement in open-
circuit voltage led to a certified
power conversion efficiency
of 24.4%, and encapsulated
devices retained 90% of their
initial efficiency after 400 hours
of maximal power point operat-
ing conditions. —PDS
Science, this issue p. 108SEX DETERMINATION
Two rather than one
For several decades, it has been
believed that the mammalian
sex-determining gene Sry con-
tains a single exon. Miyawaki et
al. have now identified a cryptic
second exon of mouse Sry.
Loss- and gain-of-function anal-
yses revealed that the two-exon
SRY (SRY-T), not the canoni-
cal single exon–encoded SRY
(SRY-S), is the bona fide testis-
determining factor. Sry exon2 is
composed of retrotransposon-
derived sequences. The SRY-S
carboxyl terminus contains a
degradation sequence (degron),Edited by Caroline Ash
and Jesse SmithIN OTHER JOURNALS
CATA LYS I S
A sintering-avoiding
support
Heterogeneous catalysts
containing dispersed metal
nanoparticles (NPs) on sup-
ports such as metal oxides orcarbon can undergo sintering
at high temperatures, a process
in which the diffusion of metal
atoms results in larger NPs with
smaller surface areas. Chen et
al. reduced a melt of NaBH 4 ,
NaNH 2 , and noble metal salts
(Au, Pd, and Pt) to form metalwhereas the SRY-T carboxyl
terminus encoded in the Sry
exon2 is degron free, thereby
conferring protein stability on
SRY-T. —BAP
Science, this issue p. 121DEVELOPMENTAL BIOLOGY
Convergence of
paradigms yields patterns
In embryo development, spatial
patterns of distinct cell types
arise reproducibly. In the
zebrafish spinal cord, neural
progenitors form stereotypic
stripe patterns despite the noisy
instructive signals and large-
scale cellular rearrangement
required during morphogen-
esis. Tsai et al. show that a cell
type–specific adhesion code,
regulated by a Shh morphogen
gradient composed of three
adhesion molecules, provides
adhesion specificity for three
neural progenitor types and
mediates patterning robustness
in the zebrafish spinal cord.
Although insufficient on their
own, the integration of the mor-
phogen gradient and differential
adhesion mechanisms enables
robust pattern formation during
tissue morphogenesis. —BAP
Science, this issue p. 113CORONAVIRUS
How SARS-CoV-2
hides its mRNA
Severe acute respiratory
syndrome coronavirus 2
(SARS-CoV-2) uses a meth-
yltransferase to cap its
messenger RNAs to prevent
them from being recognized by
the host immune system and
ensure their translation in host
cells. Rosas-Lemus et al. solved
crystal structures for the SARS-
CoV-2 methyltransferase in
complex with its methyl donor
and cap structure substrates,
a reaction product, and an
inhibitor. These structures offer
potential strategies for develop-
ing therapeutics that disrupt the
formation of the active methyl-
transferase complex or block its
catalytic activity. —AMV
Sci. Signal. 13 , eabe1202 (2020).Leprosy is a disfiguring mycobacterial infection with a distinctive genetic
signature in some human populations for either susceptibility or protection.IMMUNOGENOMICSLeprosy-associated genetics
L
eprosy, caused by Mycobacterium leprae, occurs
worldwide, but some individuals are more susceptible to
the disease than others. Genes associated with leprosy
have been mapped to the human leukocyte antigen
(HLA) proteins, which are responsible for the regulation
of the immune system. However, the HLA region is quite vari-
able, and mapping specific disease-associated mutations is
difficult. Dallmann-Sauer et al. have succeeded in sequenc-
ing, mapping, and genotyping 11 HLA genes in a case-control
design of 1155 Vietnamese individuals. Four leprosy-
associated amino acid variants were identified within these
genes, which comprised two pairs of linked genes, with one
set conferring susceptibility and one being protective. This
study exemplifies how examination of underrepresented
populations can help to identify genetic factors that may
reveal vulnerabilities to disease around the world. —LMZ
PLOS Pathog. 16 , e1008818 (2020).