The when of Mediterranean water outflow

sciencemag.org SCIENCE

body size. Dinosaur metabolism

seems to have been neither fast

nor slow, but somewhere in the

middle—so, dinosaurs did not

fully regulate their internal tem-

perature but they were also not

entirely at the whim of the envi-

ronment; neither slow goliaths

nor supercharged reptiles. — SNV

Science, this issue p. 1268

NONHUMAN GENETICS

Male chimps evolve faster with ageChimpanzees are evolving

faster than humans. Venn et al.

examined the genetics of three

generations of western chimpan-

zees and found that overall the

mutation rate is similar between

humans and chimpanzees.

However, while male humans had

three to four times the mutation

rate of females, in chimpanzees

the sex difference was even

higher, with a male mutation rate

five to six times that of females.

Blame aging dads. For every extra

year of the father’s age, baby

1238 13 JUNE 2014 • VOL 344 ISSUE 6189

Edited by Stella HurtleyI N SC IENCE J O U R NA L S

RESEARCH

NEURONAL REPAIR

Improving stroke recovery by timing treatmentPatients recovering from strokes

often fight a long uphill battle,

with mixed results. Studying

the effect of physical training

on regeneration from damaged

nerves in a model of stroke in

rats, Wahl et al. show that timing

matters. First, the researchers

gave the rats a stroke, which

damaged their ability to reach

for food pellets with their

forelimbs. The researchers then

gave them physical training and

treated them with an antibody to

encourage neural regeneration.

The rats improved more when

the researchers waited until

after the antibody treatment to

start the training. Damaged cir-

cuits, it seems, need a little time

to regrow before being called

into action. — PJH


DINOSAUR PHYSIOLOGY

Not too fast, not too slow, somewhere in betweenIn early depictions, dinosaurs

lumbered slowly, dragging their

tails. More recently, we have

imagined them lifting their tails

and running. The question boils

down to whether dinosaurs had

energetic systems closer to those

of rapidly metabolizing mammals

and birds, or to those of slower

reptiles that do not internally

regulate their body temperature.

However, determining the meta-

bolic rate of extinct organisms

is no easy task. Grady et al. ana-

lyzed a huge data set on growth

rate in both extinct and living

species, using a method that

considers body temperature and

PALEOCEANOGRAPHY

The when of Mediterranean water outflow

The trickle of water that began to flow from the

Mediterranean Sea into the Atlantic Ocean after the

opening of the Strait of Gibraltar turned into a veritable

flood by the end of the Pliocene 2 to 3 million years ago.

It then began to influence large-scale ocean circulation

in earnest. Hernández-Molina et al. describe marine sedi-

ment cores collected by an ocean drilling expedition (see

the Perspective by Filippelli). The results reveal a detailed

history of the timing of Mediterranean outflow water activity

and show how the addition of that warm saline water to the

cooler less-salty waters of the Atlantic was related to climate

changes, deep ocean circulation, and plate tectonics. — HJS

Science, this issue p. 1244; see also p. 1228

Integrated Ocean Drilling Program expedition in the Gibraltar gateway.

body size. Dinosaur metabolism

seems to have b

NAL REPAIR

ing stroke recovery ng treatme t

AL REPAIR

Crayfish can become nervous too in stressful situations Fossat et al. p. 1293

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SCIENCE sciencemag.org

chimpanzees exhibited approxi-

mately one extra mutation. This

finding will inform future studies

of primate evolution. — LMZ


QUANTUM GASES

Tilting just right makes atoms tunnelOne of the most fascinating

phenomena in the quantum

world is the ability of particles to

go through an energy barrier — a

process called quantum tunnel-

ing. Meinert et al. studied the

dynamics of quantum tunneling

in an optical lattice of strongly

interacting atoms. When the

lattice was suddenly tilted, the

atoms, originally each in their

own lattice site, tunneled to non-

neighboring sites. — JS


CANCER IMAGING

Taking a broader view of cancer imagingMany people think the best way

to visualize tumors is to target

imaging agents to specific cancers

at the molecular level. Kuo et al.

feel differently: They developed

a new class of small molecules,

called alkylphosphocholine (APC)

analogs, which are broadly taken

up by nearly all cancers, without

such molecular specificity.

Compared to normal cells, cancer

cells have a strong taste for APC

analogs. By attaching fluorescent

13 JUNE 2014 • VOL 344 ISSUE 6189 1239

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Edited by Kristen Mueller

and Jesse SmithIN OTHER JOURNALS

NEUROLOGICAL DISEASE

Skin may hold the key for Parkinson’s In Parkinson’s disease, a degen-

erative movement disorder of

the central nervous system, a

protein called phosphorylated

alpha-synuclein builds up in

neurons, damaging the brain. The

disease is hard to diagnose early

or monitor over time because the

protein builds up so slowly and

so deep inside the brain. Doppler

et al. now report that patient skin

samples hold key insights. The

authors detected phosphorylated

alpha-synuclein in autonomic and

sensory nerves found in the skin

samples in 16 out of 31 people

diagnosed with Parkinson’s

disease and in 0 out of 35 healthy

volunteers. Because skin is far

more accessible than brain tissue,

these observations could lead

to diagnostic tests to identify

and follow the progression of

Parkinson’s disease. — PJH

Acta Neuropathol. 10.1007/s00401-

014-1284-0 (2014).

EDUCATION

Active learning: The twilight of Chem 101?Should professors continue

to use traditional lectures in

labels or radiolabels to the APC

analogs, the researchers could

image more than 50 different

human cancers in animal models,

as well as brain, lung, and liver

tumors in human patients.

These broadly applicable APC-

based agents for imaging—and

possibly for treatment—are now

poised for further translation to

clinical trials. — MLF

Sci. Transl. Med. 6, 240ra75 (2014).

EARTH’S INTERIOR

Cycling water through the transition zoneThe water cycle involves more

than just the water that circulates

between the atmosphere,

oceans, and surface waters. It

extends deep into Earth’s interior

as the oceanic crust subducts, or

slides, under adjoining plates of

crust and sinks into the mantle,

carrying water with it. Schmandt

et al. combined seismological

observations beneath North

America with geodynamical

modeling and high-pressure

and -temperature melting

experiments. They conclude that

the mantle transition zone—

410 to 660 km below Earth’s

surface—acts as a large reservoir

of water. — NW


CANCER METASTASIS

Copper for breast cancer metastasis Many patients with breast cancer

die from metastases, when can-

cer cells spread from the primary

tumor to other sites. Some of the

intracellular proteins that help

cells move from one location

to another can be activated by

a chemical modification called

oxidation. MacDonald et al. found

that the enzyme Memo bound

copper, enhancing the oxida-

tion of proteins involved in cell

movement. Mice with tumors

formed from breast cancer cells

that lacked Memo had fewer lung

metastases, and human patients

with breast cancers that had high

levels of Memo were more likely

to develop metastases. — WW

Sci. Signal. 7, ra56 (2014).

NEUROSCIENCE

Making excitatory synapses slow (or fast)

Glutamate is the most widely used neurotransmitter in the

brain. Glutamate receptors in the mammalian brain are

macromolecular complexes assembled from a pool of

different proteins. Several proteins in these complexes,

including cornichon homolog 2 (CNIH2), are known to

influence the workings of certain glutamate receptors of the

AMPA type, but their precise roles are unknown. Boudkkazi et al.

recorded synaptic transmission between hippocampal neurons

and inhibited CNIH2 expression with small interfering RNAs

to investigate the role CNIH2 plays at different synapses. They

found that CNIH2 profoundly affected the timing of synaptic

transmission—CNIH2 slowed things down, whereas its absence

sped things up. Such careful kinetic regulation is necessary

because speed is more important for some tasks, whereas

reliability, the successful transmission of a signal across the

synapse, is more important for others. — PRS

Neuron 82, 848 (2014).

Glutamate release

in a neuronal synapse.

Published by AAAS

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SCIENCE sciencemag.org 13 JUNE 2014 • VOL 344 ISSUE 6189 1240-B

STEM CELL PLASTICITY

The versatility of epithelial stem cellsStem cells are very important in the maintenance of our bodies’ tissues and organs. Blanpain and Fuchs review how differ-ent populations of naturally lineage-restricted epithelial stem cells and committed progeni-tors can also display remarkable plasticity. These cells can re-acquire long-term self-renewing capacities and multilineage differentiation potential during physiological and regenera-tive conditions. These abilities depend on whether the stem cell remains within its resident niche or has been mobilized to repair a wound. Such cellular plasticity has implications for regenerative medicine and for cancer. — BAP


QUANTUM NONLOCALITY

Testing nonlocality for many particlesDistant parts of a quantum-mechanical system can be correlated in ways that cannot be described classically—a concept known as nonlocality. Tura et al. propose a simple test for nonlocality in systems with mul-tiple particles. The test involves quantities that should readily be measurable in, for example, cold atom experiments. This is an improvement over currently avail-able tests, which are difficult to implement experimentally. — JS


QUANTUM MECHANICS

Avoiding back-action in quantum measurementsThe very process of measuring a quantum system has an influ-ence on the system through the process of back-action. Suh et al. used a back-action evasion scheme to monitor the motion of a miniature oscillator without influencing its motion (see the

Perspective by Bouwmeester). The scheme should help in the understanding of the fundamental limits associated with measurement and will have practical implications in providing a low-temperature thermometer and a probe of extremely weak forces. — ISO


NEURAL MIGRATION

Dissecting how signaling directs axon growth During development of the nervous system, nerve cells send out projections called axons that must be guided to their proper targets. Netrins are secreted proteins that bind to receptors to either attract or repel the growing axons. Xu et al. present x-ray structures that show that complexes of netrin with two different recep-tors, neogenin and DCC, have different architectures. How netrin signals remains to be understood in detail, but netrin’s ability to create different assem-blies probably plays a role in the diverse signaling outcomes it mediates. — VV


HUMAN GENETICS

The population structure of Native Mexicans The genetics of indigenous Mexicans exhibit substantial geographical structure, some as divergent from each other as are existing populations of Europeans and Asians. By performing genome-wide analy-ses on Native Mexicans from differing populations, Moreno-Estrada et al. successfully recapitulated the pre-Columbian substructure of Mexico. This ancestral structure is evident among cosmopolitan Mexicans and is correlated with subcon-tinental origins and medically relevant aspects of lung func-tion. These findings exemplify

the importance of understand-ing the genetic contributions of admixed individuals. — LMZ


TRANSCRIPTION

Pausing for control of gene expressionPausing during gene transcrip-tion can play a critical role in gene regulation. Vvedenskaya et al. mapped pause sites across the whole genome in actively growing Escherichia coli (see the Perspective by Roberts). Thousands of undocumented pause sites were identified across well-transcribed genes, allowing the definition of a con-sensus pause sequence that is dependent on specific interac-tions of RNA polymerase with the DNA template and nascent RNA transcript. — GR

Science, this issue p. 1285;

see also p. 1226

DISEASE ECOLOGY

Many connections are not always bad for healthContrary to expectations, highly connected populations can experience less impact from infectious disease than isolated groups. What happens to pathogens in natural popula-tions has been poorly studied, because they rarely cause devastating disease outbreaks. Thanks to a long-term study of an inconspicuous fungal-plant disease system, we have now gained some surprising insights. During a 12-year study, Jousimo et al. discovered that clustered and linked host-plant patches showed lower levels of fungal damage and higher fungal extinction rates than more distant patches (see the Perspective by Duffy). This phenomenon is explained by high gene flow and rapid evolu-tion of host resistance within the connected patches. Populations of the modest weed Plantago,

growing on the Åland Islands in the Baltic, were less than 10% infected by the Podosphaera mildew fungus in any given year, but infection turnover was high. These findings have broad implications for ecology, disease biology, conservation, and agri-culture. — CA

Science, this issue p. 1289; see also p. 1229

COMPARATIVE BEHAVIOR

The crayfish that was afraid of the lightWe tend to assume that complex emotions, such as anxiety, only occur in mammals or other cog-nitively complex vertebrates. But a heightened sense of aware-ness and the avoidance of novel or dangerous environments could be helpful for any animal species. Fossat et al. show that crayfish exposed to a stress-ful electric field refuse to enter light arms in a light/dark maze, even after the electric field has been removed. The animals calmed down when they were injected with an anxiolytic drug used to treat anxiety in humans, and they entered the light as normal. The stressed animals had increased levels of the neu-rotransmitter serotonin in the brain, and injections of serotonin induced anxiety-like behavior in control animals. Thus, these invertebrates display a primi-tive form of anxiety that shares a mechanism with the more complex emotions displayed by vertebrates. — SNV


RESEARCH

Edited by Stella HurtleyALSO IN SCIENCE

0613eISIOR1.indd 1240-B 6/18/14 11:06 AM

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The when of Mediterranean water outflow