Strong yet creeping megathrust faults

sciencemag.org SCIENCE1016 29 AUGUST 2014 • VOL 345 ISSUE 6200

HUMAN MICROBIOTA

Signature microbes follow you from house to houseHouseholders share more than habitation; they also share inhab-itants. In a diverse sample of U.S. homes, Lax et al. found that peo-ple and animals sharing homes shared their microbial communi-ties (microbiota) too, probably because of skin shedding and

RESEARCH

hand and foot contamination. When families moved, their microbiological “aura” followed. If one person left the home even for a few days, their contribution to the microbiome diminished. These findings have implications not only for household identity and composition, but also for indicators of the members’ health and well-being. — CA

Science, this issue p. 1048

STELLAR DISTANCES

Distance score settledfor Seven SistersMost of us have seen the Pleiades star cluster in the night sky, one of the few groups of physically related stars that are separately visible to the naked eye. In spite of its proximity to us, its distance has been disputed. Melis et al. settle the controversy

with astrometric measurements from radio interferometry that reveal a distance of 136.2 parsecs (see the Perspective by Girardi). Other methods yielded similar values, but the trusted astrome-try satellite Hipparcos measured only 120.2 parsecs. The new result alleviates the concern that astronomers would need to adjust their stellar evolution mod-els to align with the Hipparcos distance. — MMM

Science, this issue p. 1029; see also p. 1001

EARTHQUAKE DYNAMICS

Strong yet creeping megathrust faultsPowerful faults in subduction zones, called “megathrust faults,” produce the largest earthquakes on Earth. Gao and Wang use heat flow data to show that when the faults subduct jagged sea floor, they generate tamer earthquakes than do faults that subduct smooth sea floor. The rugged sea floor brings irregularities into the fault that cause it to deform slowly over time, which results in a comparatively higher fault strength and lower seismicity. The finding has a direct impact on assessing regional earthquake and tsunami hazards. — BG


EVOLUTIONARY GENOMICS

Rabbits softly swept to domestication When people domesticate animals, they select for tame-ness and tolerance of humans. What else do they look for? To identify the selective pressures that led to rabbit domestication,

I N SC IENCE J O U R NA L SEdited by Melissa McCartney and Margaret Moerchen

CONSERVATION ECONOMICS

Cost-effective conservation on private land

How affordable is biodiversity conservation in a fragmented landscape? Banks-Leite et al. asked this question for the biodiversity hotspot of the Brazilian Atlantic Forest. An annual investment of <10% of Brazil’s agricultural subsidies could support effective ecological restoration on private lands. This would increase biodiversity in set-aside land to the same level observed in protected areas. The cost-effectiveness of this scheme suggests a path

forward for conservation strategies in other similarly mixed landscapes, too. — AMS


Squeezing out changes in a borosilicate glass structureEdwards et al., p. 1027

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Carneiro et al. sequenced a

domestic rabbit genome and

compared it to that of its wild

brethren (see the Perspective

by Lohmueller). Domestication

did not involve a single gene

changing, but rather many gene

alleles changing in frequency

between tame and domestic

rabbits, known as a soft selective

sweep. Many of these alleles

have changes that may affect

brain development, supporting

the idea that tameness involves

changes at multiple loci. — LMZ


IMMUNOLOGY

Cutting out a kinase for T cell survivalSufficient numbers of T cells

are required in the body to fight

pathogens. To survive, T cells

need to receive signals through

both the T cell receptor and the

interleukin-7 receptor. However,

constant interleukin-7 receptor

activation causes T cells to die,

so the T cell receptor intermit-

tently blocks the activity of the

interleukin-7 receptor. Signaling

through the interleukin-7 recep-

tor requires the kinase Jak1. Katz

et al. found that T cells contained

very little Jak1 protein and that it

was unstable. When researchers

activated the T cell receptor, they

generated increased amounts of

microRNA. The microRNA pre-

vented the T cells from producing

new Jak1 protein and interfered

with the ability of the interleu-

kin-7 receptor to signal. — JFF

Sci. Signal. 7, ra83 (2014).

CELL MIGRATION IN 3D

Push me, pull you, that’s the way to movePrimary cells, derived directly

from human tissue, exhibit

different behaviors in shape

and signaling within three-

dimensional (3D) or 2D spaces.

When the pressure within the cell

increases, cells display limb-like

bumps, which they use to move

through their 3D environment.

Petrie et al. now show that when

the complex of actin and myosin

IN OTHER JOURNALS

HUMAN BEHAVIOR

Incentives work on economists, too!Editors treasure prompt and

informative referees. Chetty et al.

show that modest psychological

and economic nudges can speed

up how rapidly referees return

their reviews without degrading

their quality. In a randomized

experiment involving 1500

referees at the Journal of Public

Economics, they offered some

referees $100 for turning in their

reviews by the 4-week deadline,

whereas they told others, who

had agreed to a 6-week dead-

line, that their delivery dates

would be posted publicly. From a

comparison across these groups

and the non-incentivized controls,

they conclude that 4 weeks is

enough and that both social pres-

sure and money work. — GJC

J. Econ. Perspect. 28, 169 (2014).

PHYSICS

Eliminating the effects of the pesky bulkA material’s imperfections can

greatly influence how well it

conducts electricity. Theoretical

physicists have, however, come

up with the concept of topologi-

cal insulators (TIs): materials

that conduct only at their sur-

face in a way that makes them

contracts, it controls the pres-

sure within cells and therefore

the shape of those protruding

structures (see the Perspective

by DeSimone and Horwitz). The

authors measured internal pres-

sures in migrating mammalian

cells. In the 3D matrix, those cells

have higher pressure that differs

between the front and back of

the cell, which creates a piston

effect. — SMH


PAIN

An enzyme offers a new path to pain controlMany people suffer from uncon-

trolled pain, and new drugs are

needed. Zambelli et al. build on

the fact that aldehydes—mol-

ecules that occur naturally in the

body—can cause pain directly.

Specifically, an enzyme that

degrades aldehydes is a key regu-

lator of pain. Mice with genetically

inactive versions of the enzyme

are extra sensitive to a painful

stimulus. Conversely, revving up

the enzyme with a drug reverses

this effect. New drugs that modu-

late aldehyde levels could benefit

patients, possibly without risk of

addiction. These results may also

explain the greater pain sensitiv-

ity in East Asians, many of whom

carry a relevant mutation. — KLK

Sci. Transl. Med. 6, 251ra119 (2014).

HUMAN BE

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show tha

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Adc17 modifies

proteasomes levels

PROTEOSTASIS

Need proteasomes? Make some!

Cells need to clear out damaged proteins, or they age

and become unhealthy. To do this, cells use tiny protein-

destroying machines called proteasomes. Building

these proteasomes is a complex process, and it’s not

clear how stressed cells can make sure the proteasome

supply meets demand. Working with yeast cells, Hanssum et

al. discovered a protein that helps cells assemble just enough

proteasomes to fit their needs. In a process called chaperoning,

the protein, which they called Adc17, helps pair two proteasomal

proteins, Rpt6 and Rpt3, during proteasome assembly. — SMH

Mol. Cell 10.1016/j.molcel.2014.06.017 (2014).

Edited by Melissa McCartney

and Margaret Moerchen

Aldehyde levels

influence pain

response

Published by AAAS

sciencemag.org SCIENCE1018-B 29 AUGUST 2014 • VOL 345 ISSUE 6200

RESEARCH

CIRCUMSTELLAR DISKS

A cosmic dust stormthat came and wentUnseen planets may still kick up a

lot of dust. While rocky exoplanets

finish their growth, destructive

collisions among them throw off

clouds of fine debris that shine

bright in the infrared. Meng et

al. monitored the star ID8 with

the Spitzer Space Telescope and

observed a rapid thermal flareup

and fadeout within only 2 years.

This modulation is consistent

with recent collisions among

its orbiting protoplanets. Such

dynamic variations in presumed

planet-forming systems encour-

age more studies that exploit the

real-time changes. – MMM


SUPERFLUIDITY

Making a superfluid lithium mixtureAt some of the coldest tempera-

tures achieved in the laboratory,

researchers can coax dilute

gases of atoms into becoming

a superfluid, with the whole gas

behaving as one entity. Bosonic

atoms, which like to congregate

in one state, achieve this willingly.

Fermions, which effectively repel

each other, require more persua-

sion. Ferrier-Barbut et al. made a

superfluid mixture of two gases,

one made up of bosons and

one of fermions. They used two

isotopes of lithium, fermionic 6Li

and bosonic 7Li. When they made

the mixture oscillate, the two

components took turns feeding

energy into each other. – JS


GLASS STRUCTURE

Catching changing boron coordinationLaboratory glassware and

kitchen cookware alike are made

of glass that contains different

cations, including boron, sodium,

and aluminum. Properties of

glass depend on the number and

location of oxygen atoms sur-

rounding each cation. Edwards

et al. combine nuclear magnetic

resonance measurements

with theoretical calculations to

understand structural transfor-

mations in borosilicate glass (see

the Perspective by Youngman).

Boron atoms in planar threefold

coordination move out of plane

with increasing pressure to form

trigonal pyramids. Identification

of this type of transition state

connects structural evolution

with stress-induced processes

in amorphous materials. In boro-

silicate glass, the transition leads

to the formation of tetrahedral

fourfold-coordinated boron that

tunes glass properties for use in

numerous applications. – BG


HUMAN GENETICS

Arctic genetics comes in from the cold Despite a well-characterized

archaeological record, the

genetics of the people who

inhabit the Arctic have been

unexplored. Raghavan et al.

sequenced ancient and modern

genomes of individuals from the

North American Arctic (see the

Perspective by Park). Analyses

of these genomes indicate

that the Arctic was colonized

6000 years ago by a migration

separate from the one that gave

rise to other Native American

populations. Furthermore, the

original paleo-inhabitants of the

Arctic appear to have been com-

pletely replaced approximately

700 years ago. – LMZ


ION CHANNEL STRUCTURE

Activating a receptor to excite a neuronTransmitting signals between

nerve cells, occuring at struc-

tures known as synapses, is

critical to processes such as

learning and memory. Fast

transmission occurs when

glutamate is released from a

presynaptic neuron and binds to

ionotropic glutamate receptors

(iGluRs) in the cell membrane of

a postsynaptic neuron. The iGluR

Edited by Melissa McCartney and Margaret MoerchenALSO IN SCIENCE JOURNALS

Published by AAAS

SCIENCE sciencemag.org 29 AUGUST 2014 • VOL 345 ISSUE 6200 1018-C

contains an ion channel that is

transiently opened, to activate

the postsynaptic neuron, but

then closes rapidly. Chen et al.

and Yelshanskaya et al. report

crystal structures in a range of

conformations that together pro-

vide insight into how glutamate

binding causes the channel to

open and how other molecules

that bind to the receptor modu-

late this. The information could

aid in the design of drugs to treat

cognitive impairment or seizure

disorders – VV

Science, this issue p. 1021 and p. 1070

MEMORY ENHANCEMENT

Brain stimulation to improve human memoryThe hippocampus is a crucial

brain area for certain types of

memory. Working with humans,

Wang et al. found that a specific

type of non-invasive brain stimu-

lation improved memory tests

and enhanced information flow

between the hippocampus and

a number of other brain regions.

This increased connectivity was

highly specific for the individual

target areas selected for each

participant. – PRS


CHROMATIN REGULATION

Chromatin mutations disrupt development Histone proteins form the core

packaging material for our

genomic DNA, and covalent

modifications to amino acid

residues in their structure play an

important role in the epigenetic

control of gene expression. Herz

et al. show that specific muta-

tions in the residues that are

normally modified to regulate

expression cause severe disrup-

tion of normal development in

the fruit fly. Similar mutations are

known to be involved in a subtype

of aggressive pediatric brain can-

cers. Insights into the epigenetic

regulatory pathways disrupted

by these mutations in Drosophila

may suggest possible treatments

for human cancers. – GR


GERMINAL CENTERS

T and B cells’ intricate molecular danceGenerating high-affinity antibod-

ies to fight infection is no easy

task. To do so requires multiple

steps, including T cells interact-

ing with antibody-producing

B cells in lymph nodes. These

interactions select B cells

expressing high-affinity antibod-

ies for further proliferation,

ensuring that the immune

response generates high-affinity

antibodies in large quantities.

Shulman et al. use fluorescent

live-cell imaging in mice to

determine the molecular details

of these interactions. They find

that T cells engage B cells in

short-lived mobile contacts

during selection. These contacts

cause T cells to flux calcium

and produce proteins called

cytokines, which probably drive

B cells to proliferate and produce

high-affinity antibodies. – KM


MICROBIAL METABOLISM

Oxidizing hydrogen in place of nitriteMicroorganisms are important

drivers of Earth’s nitrogen cycle.

Many of the organisms responsi-

ble for mediating the reactions of

one phase of nitrogen to another

are thought to be ecologic

specialists. Using a combination

of genomic and experimental

analyses, Koch et al. show that

Nitrospira moscoviensis, a

member of a widely distributed

genus of nitrite-oxidizing bacte-

ria, can oxidize hydrogen instead

of nitrite to support growth when

oxygen is present. Not only does

this ecologic flexibility suggest

a broader distribution of these

organisms in natural settings,

but they may be important in

engineered environments as

well. – NW


PALEOCEANOGRAPHY

El Niño shifted between the center and the EastEl Niño has changed quite a

bit over the past 10,000 years.

During some periods it was less

variable than now, and during

others it shifted from its current

locale toward the central Pacific.

Carré et al. analyzed the shells of

mollusks from Peru to construct

a record of the El Niño–Southern

Oscillation (ENSO) in the eastern

Pacific over the Holocene period.

They compared this record with

other records from the rest of

the Pacific to reveal how much

the strength and frequency of

El Niños changed and how their

positions varied. – HJS


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Strong yet creeping megathrust faults