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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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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

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Broadening the source for hot spotsBrent Grocholski

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