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25 SEPTEMBER 2015 • VOL 349 ISSUE 6255 1501SCIENCE sciencemag.org
insertion sites by a specific DNA
binding protein, Sap1, which
forms DNA replication–fork
barriers.
Science, this issue p. 1549
IMMUNOLOGY
Mitochondria signal ’eat me’Cardiolipin becomes exposed
if mitochondria become
damaged. Under these cir-
cumstances it becomes an
“eat me” signal. Cardiolipin is
a phospholipid found in the
inner mitochondrial membrane
and in bacterial membranes.
Balasubramanian et al. show
that cardiolipin stimulates
macrophages to phagocytose
the damaged cells. But it also
inhibits cytokine production
from macrophages when they
encounter bacterial lipopoly-
saccharide, which resembles
cardiolipin in structure. — JFF
Sci. Signal. 8, ra95 (2015).
EVOLUTIONARY ECOLOGY
Climate change decoupling mutualismMany coevolved species have
precisely matched traits. For
example, long-tongued bumble-
bees are well adapted for
obtaining nectar from flowers
with long petal tubes. Working
at high altitude in Colorado,
Miller-Struttmann et al. found
that long-tongued bumblebees
have decreased in number
significantly over the past 40
Edited by Kristen Mueller
and Jesse H. Smith IN OTHER JOURNALS
DEVELOPMENT
A wild hair day for micePetting your cat backward will
probably elicit a not-so-friendly
response. This is because
a cat’s fur grows from hair
follicles that have a specific
orientation. Proteins that
make up the planar cell polar-
ity (PCP) signaling pathway,
which regulate the polarization
of groups of cells on a plane,
help orient hair follicle growth
in many vertebrates. Chang et
al. now report on an intriguing
mouse strain that has a ridge of
hair across their backs where
the hair follicles are oriented
in the opposite direction.
Mutations in the genes that
encode Frizzled 6, a PCP pro-
tein, and Astrotactin2, known
EVOLUTIONARY ECOLOGY
Successional specialism in forests
In forests, different tree species tend to occupy different stages
of ecological succession, a process whereby the species
structure of a particular habitat changes over time. However,
scientists do not fully understand the evolutionary relation-
ships behind these patterns. Letcher et al. studied this in
tropical forest tree species across a gradient of precipitation.
Specialism for particular stages of succession tended to be
more conserved in related species in wet forest species than
in dry forest species. More extreme environmental differences
between early and late successional habitats in wet forest than in
dry forest may cause this pattern, leading to successional niche
similarity within species-rich rainforest tree lineages. — AMS
J. Ecol. 103, 1276 (2015).
Generalist bees replace specialists as climate warms
The types of tree
species present in
forests evolve over time
years. Short-tongued species,
which are able to feed on many
types of flowers, are replac-
ing them. This shift seems to
be a direct result of warming
summers reducing flower
availability, making generalist
bumblebees more successful
than specialists and resulting
in the disruption of long-held
mutualisms. — SNV
Science, this issue p. 1541
VIROLOGY
Therapeutic opportunity knocks The urinary tract of most
adults harbors JC polyomavirus
(JCV) asymptomatically but
persistently. In immunocom-
promised individuals, JCV can
opportunistically infect the
brain to cause the debilitating
and frequently fatal disease
progressive multifocal leuko-
encephalopathy (PML). No
treatments are currently avail-
able for PML, but two papers
have identified and exploited
a gap in immune responses to
JCV. Ray et al. report that JCV
strains found in the cerebro-
spinal fluid of PML patients
have mutations that prevent
antibody neutralization and
that these blind spots can be
overcome by vaccination. Jelcic
et al. suggest that broadly
neutralizing antibodies derived
from a patient who recovered
from PML can also be used
therapeutically. — ACC
Sci. Transl. Med. 7, 306ra151, 306ra150 (2015).
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1502 25 SEPTEMBER 2015 • VOL 349 ISSUE 6255 sciencemag.org SCIENCE
RESEARCH | IN OTHER JOURNALS
for its role in guiding migrating
neurons, are responsible for giv-
ing the mice such a wild hairdo.
— BAP
PLOS Genet. 10.1371/journal.pgen.1005532 (2015).
ENERGY ECONOMICS
Uncovering site selection bias Despite internal validity and
massive replication, program
evaluations may bias out-of-
sample predictions and thus
misinform policy discussions.
Allcott analyzed 111 random-
ized controlled trials (RCTs) of
the Opower energy efficiency
intervention, involving 8.6
million U.S. households. Large-
scale replication is intended
to ensure external validity
across RCT sites, populations,
contexts, etc., but energy
utilities were not all equally
willing and able to participate.
Utilities having more environ-
mentalist customers were more
inclined to partner earlier and
to target their most high-con-
suming customers. Thus, earlier
interventions, despite many
replications, overestimated
impacts relative to effects real-
ized in later trials. — BW
Quart. J. Econ. 10.1093/qje/qjv015 (2015).
VIROLOGY
Giant virus varieties keep growingA recent fascinating develop-
ment in basic virology has
been the discovery of “giant”
viruses that are visible by light
microscopy. Legendre et al. now
report a fourth type of giant
virus called Mollivirus siberi-
cum. Like its cousin Pithovirus
sibericum, it can still infect
acanthamoeba (a common soil
protozoan) after being found
in 30,000-year-old Siberian
permafrost. Its diameter spans
0.6 µm, with a 623-kb genome,
but it differs from other giant
viruses in how it replicates, how
its genome is organized, and in
the proteins it encodes. Nearly
65% of the proteins encoded
by Mollivirus have no known
homologs. — BJ
Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1510795112 (2015).
GEOPHYSICS
Broadening the source for hot spotsCertain volcanoes are fed by
plumes of hot material originating
at the very base of Earth’s rocky
mantle. Dynamic arguments
suggest that the conduits feeding
these hot-spot volcanoes should
be narrow, because of the rela-
tively small areas over which they
erupt. French and Romanowicz
use an improved whole-mantle
seismic imaging technique to
show that plumes are actually
quite broad. Their surprising
results imply that plumes are
long-lived and may have a ther-
mochemical origin. The vertical
orientation of conduits suggests
sluggish convection deep within
the mantle. — BG
Nature 10.1038/nature14876 (2015).
LIVER CANCER
Suspicious behavior by a harmless virusEvery year doctors diagnose over
700,000 people worldwide with
liver cancer. The most common
risk factors are alcohol abuse and
chronic infection with hepatitis
B or hepatitis C viruses. A new
study hints at a possible nefari-
ous role of adeno-associated
virus type 2 (AAV2), which infects
about half of all adults with no
obvious adverse effects. Nault
et al. sequenced the genomes of
193 liver tumors and found that
11 harbored AAV2 sequences
integrated near genes previously
linked to cancer development.
The viral sequences altered the
expression of these genes, but
whether the integration events
contributed causally to tumori-
genesis is unclear. Because
modified versions of AAV2 are
used as gene therapy vectors,
answering this question is a
priority. — PAK
Nat. Genet. 10.1038/ng.3389 (2015).
ECOLOGY
Traffic noise effects on birds
Bird populations decline near roads, but teasing
apart the reasons for these declines can be diffi-
cult. To identify how road noise affects migratory
bird species, Ware et al. used traffic noise play-
backs to create a “phantom road” in a road-free
area in Idaho. Overall bird numbers were 31% lower
at the phantom road site than at a quiet control site.
Birds that stayed at the phantom road site had a lower
body condition index, an indicator of fitness.
One reason for the body condition changes is the need
for increased vigilance in a noisy environment, reduc-
ing the time available for foraging. The noise levels
used in the experiment are similar to those in sub-
urban neighborhoods and in many protected areas.
Noise reduction is thus of crucial importance
for conservation. — JFU
Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1504710112 (2015).
Traffic noise repels
and degrades the
fitness of birds like the
MacGilivray’s warbler
Transmission electron micrograph of a Mollivirus particle PH
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Broadening the source for hot spotsBrent Grocholski
DOI: 10.1126/science.349.6255.1501-f (6255), 1501-1502.349Science
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