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Article Released Wed-16th-April-2008 18:22 GMT
Contact: Ruth Institution: Nature Publishing Group
 Cell biology: Reconstituting the blood

Summaries of newsworthy papers include Why fishing magnifies fluctuations in fish abundance, Measuring a fractional electron charge, Helping the immune system, An ancient record of methane emissions, Raising the 'anti' and Sequencing gets personal


This press release is copyright Nature.

VOL.452 NO.7189 DATED 17 APRIL 2008

This press release contains:

· Summaries of newsworthy papers:

Cell biology: Reconstituting the blood

Population dynamics: Why fishing magnifies fluctuations in fish abundance

Atomic physics: Measuring a fractional electron charge

Cancer: Helping the immune system

Palaeoclimatology: An ancient record of methane emissions

Spintronics: Raising the 'anti'

And finally… Sequencing gets personal

· Mention of papers to be published at the same time with the same embargo

· Geographical listing of authors

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[1] Cell biology: Reconstituting the blood (AOP)

DOI: 10.1038/nature06869

***This paper will be published electronically on Nature's website on 16 April 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 17 April, but at a later date. ***

Blood contains an assortment of specialist cells, all of which derive ultimately from self-renewing master cells known as haematopoietic (or blood-forming) stem cells. A paper online in Nature has discovered how to confer the ‘everlasting’ property of these stem cells on to multipotent progenitor cells — their otherwise short-lived descendants.

Michael Clarke and colleagues genetically engineered mice devoid of three key genes, all normally regulated by another gene, known as Bmi1, that is essential for self-renewal of stem cells. They found that multipotent progenitor cells in these mice had acquired the capacity to self-renew as well, enabling the researchers to reconstitute the blood system in recipient mice that had been lethally irradiated to destroy their bone marrow.

In removing the genetic constraints limiting the longevity of multipotent progenitors, the team may have uncovered a clue as to how these cells could turn malignant in blood cancers.


Michael Clarke (Stanford University, Palo Alto, CA, USA)
Tel: +1 650 498 5852; E-mail:

[2] Population dynamics: Why fishing magnifies fluctuations in fish abundance (pp 835-839; N&V)

With many of the world’s fisheries in decline, it has become crucial to understand how depleted populations can be rebuilt. A paper in this week’s Nature shows that this is likely to be not just about rebuilding biomass, but also about restoring age and size structure within populations.

George Sugihara and colleagues looked into why exploited fish stocks tend to fluctuate more than unexploited ones. They analysed a 50-year-old record of fished and unfished species living in the same environment — originally set up by the California sardine fishery after its collapse in the 1940s to distinguish environmental causes from fishing effects.

The team examined three mechanisms that might account for the magnified fluctuations caused by fishing. Could they be simply due to variations in fishing pressure? Or perhaps populations dominated by small young fish left behind by commercial fishing might be less able to dampen the effects of variability in environmental factors such as wind patterns and sea-surface temperatures. The authors say that both may contribute, but the biggest factor is that these age-truncated populations are intrinsically less stable meaning that they are more likely to show cycles of boom and bust regardless of environmental variability. This makes them more susceptible to local extinction, with potentially damaging consequences for commercial fisheries.


George Sugihara (Scripps Institution of Oceanography, University of California San Diego, CA, USA)
Tel: +1 858 534 5582; E-mail:

Nils Stenseth (University of Oslo, Norway) N&V author
Tel: +47 22 85 44 00 ext 4584; E-mail:

[3] Atomic physics: Measuring a fractional electron charge (pp 829-834; N&V)

Electron charge is one of the most elementary units that we know, so it may come as a surprise that fractional electron charges can exist at all. But they do in the so-called fractional quantum Hall effect, where electrons are confined within a two-dimensional system and strongly interact with each other. So far, mostly odd-denominator fractional charges have been seen — such as a third, a fifth or a seventh of an electron charge — but a paper this week in Nature reports the observation of quarter-electron-charge 'quasiparticles'.

By manipulating the experimental conditions appropriately, quasiparticles with a fractional electron charge can be created. Merav Dolev and colleagues generated their quasiparticles with a quarter of an electron charge in an ultraclean, two-dimensional electron gas.

These quasiparticles are of considerable interest, as they have been predicted to possess the right properties to enable a novel and exotic form of quantum computation, based on topological braiding of these particles, which would be far more error-proof than conventional quantum computing approaches.


Merav Dolev (Weizman institute, Rehovot, Israel)
Tel: +972 8 9342519; E-mail:

Eduardo Fradkin (University of Illinois Urbana-Champaign, IL, USA) N&V author
Tel: +1 217 333 4409; E-mail:

[4] Cancer: Helping the immune system (AOP)
DOI: 10.1038/nature06868

***This paper will be published electronically on Nature's website on 16 April 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 17 April, but at a later date. ***

Researchers identify a protein involved in blood circulation in tumours and demonstrate that deleting it opens up the tumour to the immune system. The team believe that the protein, RGS5, could be a target for anti-cancer therapy, in particular when combined with approaches that also enhance an anti-tumour immune response.

Formation of new blood vessels in solid tumours, termed angiogenesis, enables tumour enlargement. In Nature this week, Ruth Ganss and colleagues establish a previously unknown role of RGS5, a signalling molecule, in this process and show that it alters blood vessels. They removed Rgs5 gene function, which leads to normalization of blood vessels within the tumour and allows more immune cells to target it. They conclude that their finding expands potential therapeutic opportunities.

Ruth Ganss (Western Australian Institute for Medical Research, Perth, WA, Australia)
Tel: +61 8 9224 0354; E-mail:

[5] Palaeoclimatology: An ancient record of methane emissions (pp 864-867)

The main natural sources of methane are wetlands, ruminants and biomass burning, which each confer the gas with a different carbon isotope signature. Climatic changes may have an influence on methane sources, and a paper in this week’s Nature looks into this possibility by examining variations in atmospheric methane over the last glacial–interglacial transition.

Past fluctuations in methane concentrations in the Northern Hemisphere are largely unexplained, but seem to have paralleled rapid changes in glacial climate. Hubertus Fischer and colleagues have now analysed an ice-core record of carbon isotope ratios in methane over the entire glacial–interglacial transition.

They found that atmospheric methane had a shorter lifetime, and that its carbon content was isotopically much heavier, when the climate was cold, and that wetlands are an important source of methane during warming events but do not contribute significantly to methane emissions during cold climate conditions. Surprisingly, methane emissions from biomass burning stayed more or less the same over the period, irrespective of climate conditions. The authors suggest that their findings could help to improve our understanding of the atmosphere’s oxidative capacity in the past.


Hubertus Fischer (Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany)
Tel: +49 471 4831 1174; E-mail:

[6] Spintronics: Raising the 'anti' (pp 859-863)

The regions of aligned spins — the magnetic domains — in a ferromagnet can influence the electrical properties of the material, so control of domain structure is a promising avenue for manipulating the spins of electrons in the emerging field of 'spintronics'. But what about antiferromagnets, whose domains have no net magnetism and so are more difficult to probe? A paper in this week’s Nature looks at the electrical properties of an antiferromagnet and reveals effects that turn out to be comparable in magnitude to those seen in ferromagnets.

In antiferromagnets, neighbouring magnetic spins are opposed rather than aligned — which explains why these domains show no net magnetism. Ravi Kummamuru and Yeong-Ah Soh made electrical measurements on the archetypical antiferromagnet chromium and, surprisingly, detected pronounced spin-related effects.

These electrical effects are important because they are as large as the highest seen for ferromagnets, and could prove to be of practical value in spintronic devices.

Yeong-Ah Soh (Dartmouth College, Hanover, NH, USA)
Tel: +1 603 646 2738; E-mail:

[7] And finally… Sequencing gets personal (pp 872-876; N&V)

Two months and less than $1 million is all it takes to sequence an individual genome, according to research in Nature this week. The method makes use of the latest parallel sequencing instrument to analyse the genetic code of a single individual, James D. Watson.

Next-generation sequencing technologies are revolutionizing human genomics, promising to yield draft genomes much cheaper and faster. Involving no cloning of Watson’s DNA, Jonathan Rothberg and colleagues make use of such cutting-edge technology. The sequence cost less than US$1 million and a mere two months to produce, compared to the approximately US$100 million reported for sequencing Craig Venter’s genome by traditional methods. The sequence and genetic variation in it constitutes a huge resource for future discoveries, and a step towards the goal of ‘personalized genomes’ and ‘personalized medicine’.

Jonathan Rothberg (Rothberg Institute for Childhood Diseases Research, Guilford, CT, USA)
Tel: +1 203 376 9300; E-mail:

Maynard Olson (University of Washington, Seattle, WA, USA) N&V author
Tel: +1 206 685 7346; E-mail:


[8] Evolvability and hierarchy in rewired bacterial gene networks (pp 840-845; N&V)

[9] A massive binary black-hole system in OJ 287 and a test of general relativity (pp 851-853)

[10] Thermalization and its mechanism for generic isolated quantum systems (pp 854-858)


***These papers will be published electronically on Nature's website on 16 April 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 17 April, but at a later date. ***

[11] Free choice activates a decision circuit between frontal and parietal cortex
DOI: 10.1038/nature06849

[12] Chromatin decouples promoter threshold from dynamic range
DOI: 10.1038/nature06867

[13] Haem homeostasis is regulated by the conserved and concerted functions of HRG-1 proteins
DOI: 10.1038/nature06934


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.

Perth: 4

Beijing: 9

Copenhagen: 5

Kangaslampi: 9
Piikkio: 9

Grenoble: 5

Bremerhaven: 5
Heidelberg: 4, 8, 9
Jena: 11

Athens: 9

Bangalore: 13

Rehovot: 3

Osaka: 9
Otsu: 2

Cracow : 9

Barcelona: 8
La Palma: 9
Madrid: 9

Bern: 5

Keelung: 2
Taipei: 2

Canakkale: 9

Birmingham: 9
London: 2
Oxford: 2


La Jolla: 2
Los Angeles: 10
Palo Alto: 1
San Francisco: 12

Bradford: 7
Guilford: 7
New Haven: 7

Urbana: 6

Bethesda: 13
College Park: 13

Boston: 10, 13
Cambridge: 12

Ann Arbor: 1

New Hampshire
Hanover: 6

New York
Rochester: 1

Philadelphia: 12

Houston: 7

Seattle: 2


For North America and Canada
Katie McGoldrick, Nature Washington
Tel: +1 202 737 2355; E-mail:

For Japan, Korea, China, Singapore and Taiwan
Mika Nakano, Nature Tokyo
Tel: +81 3 3267 8751; E-mail:

For the UK/Europe/other countries not listed above
Jen Middleton, Nature London
Tel: +44 20 7843 4502; E-mail

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Keywords associated to this article: Cell biology, Population dynamics, Atomic physics, Cancer, Palaeoclimatology, Spintronics, Sequencing
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