This press release contains:
Summaries of newsworthy papers:
Planetary science: Moon meets moon
Evolution: Early humans out of the woods
Neuroscience: How vampire bats ‘see’ blood
Climate science: CO2 counters warming in grassland productivity
Neuroscience: Adult neurogenesis linked to depression
Climate science: Reducing non-CO2 greenhouse gas emissions
Climate science: Calcifying phytoplankton sensitive to pH
Cancer: Epigenetic control of cancer?
Climate science: The dust connection
And finally… Growing with your gut
Mention of papers to be published at the same time
Geographical listing of authors
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[1] Planetary science: Moon meets moon (pp 69-72; N&V)
The most striking feature of the Moon’s topography — its hemispherical asymmetry — can be explained by a low-velocity collision with a smaller, companion moon, according to a paper in this week’s Nature. Martin Jutzi and Erik Asphaug present numerical simulations of such a collision, which broadly reproduce the divergent terrain and chemical composition of the Moon’s nearside and farside.
The origin of the Moon’s farside highlands has been the subject of speculation since the first measurement of the Moon’s shape, with suggested explanations ranging from spatial variations in tidal heating to asymmetric bombardment of the lunar surface. Jutzi and Asphaug consider a new possibility — that the highlands formed by the accretion of a companion moon, created at the same time as the Moon and sharing its orbit for tens of millions of years before colliding with it.
Such a collision, between co-orbiting bodies, would take place at relatively low velocity, leading to the accretion of material from the companion onto the Moon, instead of crater formation. In the authors’ simulations, the impact produces a hemispheric accretion layer consistent with the dimensions of the farside highlands, and also displaces the Moon’s subsurface ‘magma ocean’ to the opposite hemisphere, providing an explanation for the concentration of potassium, rare-earth elements and phosphorus in the nearside crust.
CONTACT
Martin Jutzi (University of Bern, Switzerland)
Tel: +41 31 631 4411; E-mail: [email protected]
Maria Zuber (Massachusetts Institute of Technology, Cambridge, MA, USA) N&V author
Tel: +1 617 253 6397; E-mail: [email protected]
[2] Evolution: Early humans out of the woods (pp 51-56; N&V)
The theory that early humans made the transition from woodland to open savannah together with the evolution of bipedality and a change in diet is questioned in Nature this week. A study of historical soil content indicates that woodland became more closed rather than less after hominins became more fully bipedal.
Features of both wooded areas and open environments have an important role in the evolution of mammals, including humans. For early hominins, shade provided by woody plants may have influenced adaptations in thermoregulatory systems or hunting behaviours; in contrast, savannahs may have influenced adaptations to new food sources and bipedalism.
Fossil soils provide information about the vegetation that once grew in them and may provide clues as to the type of ecosystem in which early hominins evolved. Thure Cerling and colleagues demonstrate that stable carbon isotopes in soils can be used obtain this information. They apply this technique to fossil soils from localities associated with early hominins in eastern Africa dating to around six million years ago. The analysis reveals that hominins evolved in a savannah-like environment with less than 40 per cent tree cover, rather than in more closed woodland.
CONTACT
Thure Cerling (University of Utah, Salt Lake City, UT, USA)
Tel: +1 801 581 5558; E-mail: [email protected]
Craig Feibel (Rutgers University, Piscataway, NJ, USA) N&V author
Tel: +1 732 445 2721; E-mail: [email protected]
[3] Neuroscience: How vampire bats ‘see’ blood (pp 88-91; N&V)
A heat-sensitive ion channel that helps vampire bats to locate veins in warm-blooded prey is identified in Nature this week. The channel, located in specialized organs in the vampire bat’s face, provides the animal with the ability to detect infrared radiation, which is seen in only three other vertebrates (all snakes).
David Julius and colleagues show that vampire bats produce a variant of a heat-sensitive ion channel (TRPV1) that is tuned to lower temperatures to act as an infrared detector. TRPV1 is activated by noxious heat (over 43 degrees Celsius), whereas the variant identified in this study has a lower thermal activation threshold (around 30 degrees Celsius). This variant is not seen in other species of bats.
In addition to identifying the channel responsible for infrared detection, examining the protein sequence of this channel in other mammals uncovers genetic relationships between vampire bats and other species. The work supports a view that vampire bats are closer, in evolutionary terms, to cows, moles and dogs than to rodents.
CONTACT
David Julius (University of California, San Francisco, CA, USA)
Tel: +1 415 476 0431; E-mail: [email protected]
M. Brock Fenton (University of Western Ontario, London, Canada) N&V author
Tel: +1 519 661 2111 ext: 86464; E-mail: [email protected]
[4] Climate science: CO2 counters warming in grassland productivity (AOP)
DOI: 10.1038/nature10274
*** This paper will be published electronically on Nature's website on 03 August at 1800 London time / 1300 US Eastern Time (which is also when the embargo lifts) as part of our AOP (ahead of print) programme. Although we have included it on this release to avoid multiple mailings it will not appear in print on 04 August, but at a later date. ***
Rising levels of CO2 in the atmosphere may counteract the drying effect of increasing temperatures on grassland productivity, by improving the efficiency of water use, according to research in Nature this week.
The productivity of grasslands is primarily limited by water. Predicted warmer and CO2-enriched conditions in the future will affect the two major photosynthetic-pathway classes of plants — C4 (‘warm season’) and C3 (‘cool season’) — but it is unclear which will be favoured. Jack Morgan and colleagues show that elevated temperatures, which cause desiccation, favour C4 grasses. However, C3 grasses are more competitive with elevated CO2, which induces stomatal closure, reduces leaf transpiration and improves water-use efficiency. Thus, the authors find that in semi-arid grasslands, the effect of increased atmospheric CO2 can cancel out the desiccating effects of moderate warming.
CONTACT
Jack Morgan (US Department of Agriculture, Fort Collins, CO, USA)
Tel: +1 970 217 4766; E-mail: [email protected]
[5] Neuroscience: Adult neurogenesis linked to depression (AOP)
DOI: 10.1038/nature10287
*** This paper will be published electronically on Nature's website on 03 August at 1800 London time / 1300 US Eastern Time (which is also when the embargo lifts) as part of our AOP (ahead of print) programme. Although we have included it on this release to avoid multiple mailings it will not appear in print on 04 August, but at a later date. ***
An inability to form new neurons in adult life may be linked to depression, a mouse study in this week’s Nature suggests.
The adult brain continually generates new neurons, a phenomenon well documented in the hippocampus, a brain region rich in stress hormone receptors. Heather Cameron and colleagues now show that blocking adult hippocampal neurogenesis disrupts endocrine and behavioural stress responses and causes depressive ‘symptoms’, such as a decreased preference for sucrose.
The data implicate adult-born hippocampal neurons in the regulation of the stress response and support a direct role for adult neurogenesis in depressive illness. This is important because better understanding of the link between stress and depression should aid the development of more effective treatments.
CONTACT
Heather Cameron (National Institute of Mental Health, Bethesda, MD, USA)
Tel: +1 301 496 3814; E-mail: [email protected]
[6] Climate science: Reducing non-CO2 greenhouse gas emissions (pp 43-50)
Substantial cuts in CO2 emissions are needed to reduce the greenhouse effect, but the impact of other greenhouse gases on Earth’s climate should not be overlooked. Reducing emissions of non-CO2 greenhouse gases could represent a fast approach to addressing climate change caused by human activity, according to a Review article in this week’s Nature.
Non-CO2 greenhouse gases, such as methane, nitrous oxide and CFCs, have a warming effect on our climate but receive far less attention than CO2. Summarizing current knowledge on non-CO2 greenhouse gases, Stephen Montzka and colleagues reveal that reducing these emissions could reduce the warming influences of greenhouse gases far more quickly than could be achieved by cutting CO2 alone. The authors explain that the climate system can respond rapidly to reduced emissions of non-CO2 greenhouse gases because they tend to have a shorter atmospheric lifetime than CO2.
CONTACT
Stephen Montzka (National Oceanic and Atmospheric Administration (NOAA), Boulder, CO, USA)
Please note this author is travelling.
E-mail: [email protected]
Edward Dlugokencky (NOAA, Boulder, CO, USA) Co-author
Tel: +1 303 497 6228; E-mail: [email protected]
James Butler (NOAA, Boulder, CO, USA) Co-author
Tel: +1 303 497 6898; E-mail: [email protected]
[7] Climate science: Calcifying phytoplankton sensitive to pH (pp 80-83; N&V)
The environmentally important, carbon-fixing phytoplankton called coccolithophores are sensitive to ocean acidification, a Nature paper suggests.
The single-celled organisms, which are covered in calcium carbonate plates called coccoliths, are responsible for a large part of modern oceanic carbonate production, yet their response to ocean acidification has been unclear. Using both contemporary surface water samples and fossil sediment cores, Luc Beaufort and colleagues show that an increase in dissolved carbon dioxide causes a decrease in calcification and coccolith mass.
Other calcifying organisms, such as corals and foraminifera, are also thought to be threatened by increasing carbon dioxide levels and ocean acidification, and the authors caution that entire marine calcifying communities could be affected in future.
CONTACT
Luc Beaufort (CNRS and Université Aix-Marseille, Aix-en-Provence, France)
Tel: +33 442 97 15 71; E-mail: [email protected]
David Hutchins (University of Southern California, Los Angeles, CA, USA) N&V author
Tel: +1 213 740 5616; E-mail: [email protected]
[8] Cancer: Epigenetic control of cancer? (AOP)
DOI: 10.1038/nature10334
*** This paper will be published electronically on Nature's website on 03 August at 1800 London time / 1300 US Eastern Time (which is also when the embargo lifts) as part of our AOP (ahead of print) programme. Although we have included it on this release to avoid multiple mailings it will not appear in print on 04 August, but at a later date. ***
The small-molecule inhibitor JQ1 may prove useful in the treatment of acute myeloid leukaemia (AML), a Nature paper suggests.
The drug delays disease progression and improves survival in mouse models of AML, and inhibits the proliferation of cultured human AML cells, Christopher Vakoc and colleagues report.
The molecule works by binding to and blocking the activity of Brd4, a protein that the team show is required for maintenance of the disease. Brd4 acts by influencing the expression of the cancer-promoting gene Myc, which itself induces a gene expression programme that drives tumorigenesis by altering the chemical composition of nuclear proteins, without change in DNA sequence. The study therefore highlights the potential of JQ1 as a therapeutically useful inhibitor, which could be used to treat AML via the elusive Myc cancer pathway.
CONTACT
Christopher Vakoc (Cold Spring Harbor Laboratory, NY, USA)
Tel: +1 516 367 5045; E-mail: [email protected]
[9] Climate science: The dust connection (AOP)
DOI: 10.1038/nature10310
*** This paper will be published electronically on Nature's website on 03 August at 1800 London time / 1300 US Eastern Time (which is also when the embargo lifts) as part of our AOP (ahead of print) programme. Although we have included it on this release to avoid multiple mailings it will not appear in print on 04 August, but at a later date. ***
Evidence of a strong link between increased dust supply to the Southern Ocean and the intense ice ages of the past million years is presented in this week’s Nature. A high-resolution sedimentary record from the South Atlantic ocean extends a previously inferred connection between dust and climate back through the past four million years, and indicates that dust may have intensified climate cooling, through ‘iron fertilization’ of the Southern Ocean.
Wind-blown dust can influence global climate by absorbing solar radiation, and also by supplying iron and other essential micronutrients to the ocean. In the Southern Ocean, where the major nutrients phosphorus and nitrogen are plentiful, iron supplied by dust can fertilize marine ecosystems, increasing their ability to remove carbon dioxide from the atmosphere. Records of wind-blown dust preserved in Antarctic ice cores have revealed correlations between dust and glacial–interglacial cycles, but these records allow only an indirect inference of the supply of dust and iron to the ocean, and extend back only 0.8 million years (Myr).
The new sediment record obtained by Alfredo Martínez-Garcia and colleagues validates the dust–climate connection inferred from ice cores, and extends it back a further 3.2 Myr, to before the beginning of the Pleistocene epoch. The record’s most striking feature, a sharp increase in dust and iron flux about 1.25 Myr ago, coincides with the development of thicker and less stable ice sheets in the Northern Hemisphere, and indicates a role for dust in the emergence of the more severe glacial–interglacial swings that characterized the late Pleistocene.
CONTACT
Alfredo Martínez-Garcia (ETH Zürich, Switzerland)
Tel: +41 44 632 46 96; E-mail: [email protected]
[10] And finally… Growing with your gut (pp 57-62)
The pattern in which intestines are folded within the body cavity is conserved between individuals and characteristic of species. This reproducible form and structure is governed by simple mechanics related to the way the body grows, a paper in this week’s Nature shows.
Throughout development the gut tube, anchored to a muscular sheet called the mesentery, grows faster than the body surrounding it, forcing it to loop. L. Mahadevan and colleagues use developmental experiments (mathematical theory and both computational and physical models) to determine what drives the characteristic looping, focusing on the chick gut. They demonstrate that pattern in which the gut loops is determined solely by the elasticity, geometry and relative rates of growth of the mesentery and gut. This model accounts for variation in gut patterns in a range of species including quail, finch and mouse.
CONTACT
L. Mahadevan (Harvard University, Cambridge, MA, USA)
Tel: +1 617 496 9599; E-mail: [email protected]
ALSO IN THIS ISSUE…
[11] A critical role for TCF-1 in T-lineage specification and differentiation (pp 63-68)
[12] Link between spin fluctuations and electron pairing in copper oxide superconductors (pp 73-75; N&V)
[13] HIV-1 adaptation to NK-cell-mediated immune pressure (pp 96-100)
GEOGRAPHICAL LISTING OF AUTHORS…
The following list of places refers to the whereabouts of authors on the papers numbered in this release. For example, London: 4 - this means that on paper number four, there will be at least one author affiliated to an institute or company in London. The listing may be for an author's main affiliation, or for a place where they are working temporarily. Please see the PDF of the paper for full details.
AUSTRALIA
Cairns: 2
Sydney: 4
AUSTRIA
Vienna: 8
CHINA
Anhui: 10
FRANCE
Aix-en-Provence: 7
Paris: 7
Perpignan: 7
Roscoff: 7
GERMANY
Bremerhaven: 7
Potsdam: 9
KENYA
Nairobi: 2
SPAIN
Barcelona: 9
Bellaterra: 7, 9
SWITZERLAND
Bern: 1
Zürich: 9, 10
UNITED KINGDOM
Edinburgh: 9
London: 13
Oban: 9
Oxford: 7
UNITED STATES OF AMERICA
Arizona
Maricopa: 4
Tucson: 2
California
San Francisco: 3, 8
Santa Cruz: 1
Colorado
Boulder: 6
Fort Collins: 4
Florida
Tampa: 2
Massachusetts
Boston: 8, 10, 13
Cambridge: 10
Maryland
Baltimore: 2, 3, 8
Bethesda: 5
College Park: 12
Frederick: 13
New York
Cold Spring Harbor: 8
Ithaca: 10
Stony Brook: 8
Ohio
Cincinnati: 8
Pennsylvania
Philadelphia: 11
Utah
Salt Lake City: 2
Washington
Redmond: 13
Wyoming
Laramie: 4
VENEZUELA
Caracas: 3
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From Japan, Korea, China, Singapore and Taiwan
Mika Nakano, Nature Tokyo
Tel: +81 3 3267 8751; E-mail: [email protected]
From the UK
Rebecca Walton, Nature, London
Tel: +44 20 7843 4502; E-mail: [email protected]
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