This press release contains:
• Summaries of newsworthy papers:
Malaria: A giant leap
Climate: A Northern Hemisphere oceanic cold snap
Physics: X-ray specs
Comment: Nuclear power, for and against
Geoscience: How to weaken a fault
Genetics: Chromosome count can go up as well as down
Photochemistry: Probing the first step in vision
And finally… Salmonella in ménage à trois
• Mention of papers to be published at the same time with the same embargo
• Geographical listing of authors
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[1] Malaria: A giant leap (pp 420-425; N&V)
The human malaria parasite evolved from a gorilla parasite after a single host transfer event according to research published in Nature this week.
The evolutionary origin of the human malaria parasite Plasmodium falciparum has been much debated. Beatrice Hahn and colleagues’ genetic analysis of almost 3,000 faecal samples from wild-living African apes demonstrates that western gorilla parasites are most closely related to the human parasite. The team show that human P. falciparum is of gorilla origin, and not as reported previously of chimpanzee, bonobo or ancient human origin.
Author contact
Beatrice Hahn (University of Alabama, Birmingham, AL, USA)
Tel: +1 205 934 0412
E-mail: [email protected]
Edward Holmes (Pennsylvania State University, University Park, PA, USA) N&V author
Tel: +1 814 863 4689
E-mail: [email protected]
[2] Climate: A Northern Hemisphere oceanic cold snap (pp 444-447)
The surface temperature of the Northern Hemisphere oceans decreased abruptly around 1970, according to a report in this week’s Nature. This surface cooling, of about 0.3 ºC in only four years, seems to account for much of the apparent hiatus in global warming that occurred in the mid-twentieth century.
The slight cooling of the Earth’s surface in the middle part of last century is usually attributed to an increase in sulphate aerosols in the lower atmosphere, or to a natural oscillation in ocean temperatures. The fact that anthropogenic aerosol emissions increased most rapidly at this time in the northern continents has also been linked to observed differences in temperature trends in the Northern and Southern hemispheres — with the south warming more rapidly than the north in mid-century.
David Thompson and colleagues have revisited twentieth-century temperature records, using an analytical method that suppresses the effects of short-term climate variability while preserving the time resolution of the data. The decrease in Northern Hemisphere sea surface temperature uncovered by this method appears to be too rapid to be explained by anthropogenic aerosols, or by currently understood ocean temperature oscillations. The suddenness of this ocean cooling event is reminiscent of the type of ‘abrupt climate change’ that has been inferred from the palaeoclimate record, but which has previously been obscured by the treatment of historical sea surface temperature data.
Author contact
David Thompson (Colorado State University, Fort Collins, CO, USA)
Tel: +1 970 491 3338
E-mail: [email protected]
[3] Physics: X-ray specs (pp 436-439; N&V)
Three-dimensional X-ray imaging is moving towards the nanoworld, according to research published in Nature this week. The researchers combine a powerful X-ray imaging technique with a method of tomographic reconstruction in order to generate three-dimensional maps of an object, having exquisite sensitivity to tiny density variations at the nanoscale.
Ptychographic X-ray imaging is a powerful technique for extracting detailed phase contrast — and hence structural — information for weakly absorbing objects. Pierre Thibault and colleagues show how such a technique can be combined with methods for tomographic reconstruction to generate full three-dimensional maps of the object under investigation: this combination of techniques is sensitive to density variations of less than 1 per cent, and can resolve structural variations as small as 100 nanometres. High-resolution quantitative tomography of this type may find applications in biomedicine and in microanalysis of fossils, as well as in materials science.
Author contact
Pierre Thibault (Technical University of Munich, Garching, Germany)
Tel: +49 89 289 14397
E-mail: [email protected]
Henry Chapman (DESY, Hamburg, Germany) N&V author
Tel: +49 40 8998 4155
E-mail: [email protected]
Comment: Nuclear power, for and against (pp 391-393)
Two Comment pieces in Nature this week put the cases for and against a nuclear future for the United States. Building nuclear power plants is the best clean alternative to coal in the near future, argue Charles D. Ferguson and Lindsey E. Marburger. Not so, counter J. Doyne Farmer and Arjun Makhijani: nuclear power is a costly mistake, and better options are at hand.
“At least 28 new 1,000-megawatt reactors will have to be built by 2035 just to keep nuclear providing the business-as-usual level of 20% of US electricity needs,” write Ferguson and Marburger. It is imperative, they argue, that applications for new reactors “be approved and that policy and economic steps are taken to ensure their success”.
“The costs of nuclear power, from the cash investment to the risks of proliferation, disaster and environmental harm, are simply too high,” respond Farmer and Makhijani — especially when many of the true costs are obscured by government subsidies. They present calculations to show that “there are plenty of workable alternatives with low-to-
Author contact
Charles D. Ferguson (Federation of American Scientists, Washington DC, USA)
E-mail: [email protected]
J. Doyne Farmer (Santa Fe Institute, Santa Fe, New Mexico, USA,
E-mail: [email protected]
[4] Geoscience: How to weaken a fault (pp 452-455)
Powdered rock only lubricates faults in the Earth’s crust during earthquake rupture, suggests a Nature paper this week. Rock powder is found in nearly every type of fault setting in the Earth's crust, and this dynamic lubrication mechanism provides an explanation for many earthquake properties.
Identifying the mechanisms that control fault weakening during rupture is one of the most central aspects of earthquake physics. Some of the factors thought to play a part, such as frictional heating, or the formation of silica gel in quartz-rich rocks, only occur at certain depths in the crust, and do not apply to all types of rock.
Ze'ev Reches and David Lockner reconstructed earthquake stress and slip rate conditions in the laboratory using solid blocks of granite. The simulated fault zone was quickly worn down to form a fine-grain rock powder or 'gouge', which reduced the fault's strength by 2–3 times. Afterwards, the powder rapidly aged and the fault regained its strength in a matter of hours to days. As this dynamic gouge lubricant can form in a wide range of fault configurations, compositions and temperatures, it may provide a comprehensive new mechanism to explain earthquake instability.
Author contact
Ze’ev Reches (University of Oklahoma, Norman, OK, USA)
Tel: +1 405 325 3157
E-mail: [email protected]
[5] Genetics: Chromosome count can go up as well as down (AOP)
DOI: 10.1038/nature09414
***This paper will be published electronically on Nature's website on 22 September 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 23 September, but at a later date. ***
Mouse liver cells can increase or decrease their chromosome content, a Nature paper suggests. The resulting genetic diversity is thought to help safeguard the liver against injury.
Liver cells are said to be polyploid — they contain more than two paired sets of chromosomes. Andrew Duncan and colleagues now show that mouse liver cells can increase their ploidy by failed cell division, or decrease their ploidy by an unusual form of cell division called multipolar mitosis. This means that the normal mouse liver contains a genetically heterogeneous mix of cells — individual liver cells have their own unique genotype with different chromosome mixtures.
It is thought that the strategy is part and parcel of the liver’s regenerative capacity, allowing ‘genetically robust’ cells to be selected from a pre-existing pool of diverse genotypes after injury. Also of interest is the fact that multipolar mitosis is usually associated with cancer cells, where it yields offspring that die. Here, multipolar mitosis yields viable cells, meaning that chromosomal instability is not necessarily associated with cancer.
Author conatct
Andrew Duncan (Oregon Health & Science University, Portland, OR, USA)
Tel: +1 503 494 6889
E-mail: [email protected]
[6] Photochemistry: Probing the first step in vision (pp 440-443; N&V)
An ultrafast spectroscopy experiment probing the photochemical reaction that initiates vision has provided the most compelling evidence yet for the involvement of an elusive phenomenon known as a conical intersection. Giulio Cerullo and colleagues present their experimental results, supported by theoretical simulations, in this week’s Nature.
The fastest and most efficient photochemical reactions are thought to involve molecular geometries for which an excited electronic state of the parent molecule has the same energy as the ground electronic state of the product molecule. These ‘conical intersections’ have so far eluded direct observation, because of the extremely fast passage of the reacting molecule through the intersection, and the rapid evolution of the energy gap between the two electronic states as the reaction proceeds.
Cerullo and colleagues used optical pulses lasting less than 20 femtoseconds (20 10−15 seconds), with a broad spectral range extending from the visible to the near-infrared, to track the progress of the rhodopsin molecule through the light-induced conformational change that initiates vision. The close agreement between the authors’ observations and theoretical simulations provides strong evidence for a conical intersection, and allows the authors to create a detailed ‘molecular movie’ of the structural changes that occur as the rhodopsin molecule changes its conformation.
Author contact
Giulio Cerullo (Politecnico di Milano, Italy)
Tel: +39 0223 996164
E-mail: [email protected]
Marco Garavelli (Università degli Studi di Bologna, Italy) – co-author
Tel: +39 051 2099476
E-mail: [email protected]
Todd Martinez (Stanford University, CA, USA) N&V author
Tel: +1 650 736 8860
E-mail: [email protected]
[7] And finally… Salmonella in ménage à trois (pp 426-429; N&V)
Salmonella Typhimurium uses a neat trick to exploit the biology of its host, enabling it to outgrow other intestinal microbes, a Nature paper reveals.
Virulence factors produced by the bacterium trigger intestinal inflammation and the production of oxygen radicals in the gut. Andreas J. Bäumler and colleagues show that these react with host-derived sulphur compounds to form a new respiratory electron acceptor, tetrathionate, which gives the bacterium a growth advantage over competing microbes that lack this ability.
Salmonella's ability to use tetrathionate as a terminal electron acceptor was already known, but the reason for this metabolic feature was a mystery. This paper demonstrates the importance of tetrathionate in the relationship between pathogen, host and other microbes, and shows how this electron acceptor enables the pathogen to 'breathe' in the intestine.
Author contact
Andreas Bäumler (University of California, Davis, CA, USA)
Tel: +1 530 754 7225
E-mail: [email protected]
Samuel Miller (University of Washington, Seattle, WA, USA) N&V author
Tel: +1 206 616 5107
E-mail: [email protected]
ALSO IN THIS ISSUE…
[8] Small RNAs are on the move (pp 415-419)
[9] Water and its influence on the lithosphere–asthenosphere boundary (pp 448-451)
[10] Damage-induced phosphorylation of Sld3 is important to block late origin firing (pp 479-483)
[11] Crystal structures of the CusA efflux pump suggest methionine-mediated metal transport (pp 484-488)
ADVANCE ONLINE PUBLICATION
***These papers will be published electronically on Nature's website on 22 September 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 them on this release to avoid multiple mailings they will not appear in print on 23 September, but at a later date. ***
[12] Crystal structure of the human symplekin–Ssu72–CTD phosphopeptide complex
DOI: 10.1038/nature09391
[13] Structure of a cation-bound multidrug and toxic compound extrusion transporter
DOI: 10.1038/nature09408
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
Canberra: 9
Hobart: 9
CHINA
Shanghai: 12
DEMOCRATIC REPUBLIC OF CONGO
Brazzaville: 1
Kisangani: 1
FRANCE
Gif-sur-Yvette: 3
Montpellier: 1
GERMANY
Essen: 6
Garching: 3
Mulheim an der Ruhr: 6
HUNGARY
Budapest: 9
ICELAND
Reykjavik: 10
ITALY
Bologna: 6
Milan: 6
REPUBLIC OF CAMAROON
Yaoundé: 1
SWIZERLAND
Villigen: 3
Zurich: 3
THAILAND
Chiang Mai: 7
UNITED KINGDOM
Cambridge: 1
Edinburgh: 1
Exeter: 2
Norwich: 2
Oxford: 6
UNITED STATES OF AMERICA
Alabama
Birmingham: 1
California
Berkeley: 6
David: 7, 8
La Jolla: 13
Los Angeles: 10
Menlo Park: 4
San Francisco: 10
Colorado
Fort Collins: 2
Illinois
Argonne: 11
Chicago: 1
Iowa
Ames: 11
Maryland
Bethesda: 1
Frederick: 1
Massachusetts
Boston: 1
Cambridge: 1
Missouri
St Louis: 1
New Mexico
Albuquerque: 1
New York
Albany: 1
Cold Spring Harbor: 8
New York: 12
Oregon
Portland: 5
Texas
College Station: 7
Washington
Seattle: 2
PRESS CONTACTS…
From North America and Canada
Neda Afsarmanesh, Nature New York
Tel: +1 212 726 9231
E-mail: [email protected]
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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