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Article Released Wed-23rd-April-2008 17:04 GMT
Contact: Ruth Institution: Nature Publishing Group
 Inside the DNA of a tropical fruit tree

Papayas are not just exotic fruits with nutritional and medicinal benefits, they are also model plants for studying genetics and evolution. Summaries of newsworthy papers include Beetle key to carbon switch, Test-tube recipe makes functioning heart cells, Linking events across a key climate transition and more

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This press release is copyright Nature.

VOL.452 NO.7190 DATED 24 APRIL 2008

This press release contains:

· Summaries of newsworthy papers:

Climate: Beetle key to carbon switch

Stem cells: Test-tube recipe makes functioning heart cells

Black holes: Seeing the light

Vision: Seeing is not behaving

Palaeoclimate: Linking events across a key climate transition

Superconductivity: Does a kink hold the key?

And finally… Inside the DNA of a tropical fruit tree

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

· Geographical listing of authors


Editorial contacts: While the best contacts for stories will always be the authors themselves, in some cases the Nature editor who handled the paper will be available for comment if an author is unobtainable. Editors are contactable via Ruth Francis on +44 20 7843 4562. Feel free to get in touch with Nature's press contacts in London, Washington and Tokyo (as listed at the end of this release) with any general editorial inquiry.

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[1] Climate: Beetle key to carbon switch (pp 987-990)

A severe outbreak of the mountain pine beetle (Dendroctonus ponderosae) is likely to change forests in British Columbia from a small net carbon sink to a large carbon source, according to research published in Nature this week.

The forests are suffering an infestation of mountain pine beetles; this is thought to be because climate change has allowed the creature to extend its range into previously inhospitable areas. Some other forest carbon dynamics models are beginning to address fire disturbances, but this is the first, to investigate insect impacts. Werner Kurz and colleagues use forest inventory and insect monitoring data alongside the Carbon Budget Model of the Canadian Forest Sector to conduct analyses of carbon stock changes with and without the current insect outbreak to demonstrate the magnitude of the impacts.

The change from sink to source, and similar effects caused by other insect pests and forest fires, could put the North American forest carbon sink at risk, and should be taken into account when modelling the impact of climate change on carbon cycling.

In a related news feature in Nature Reports Climate Change, Brian Hoyle says: "If the new study proves prophetic, even more problematic climatic days may lie ahead."

CONTACT

Werner Kurz (Canadian Forest Service, Victoria, BC, Canada)
Tel: +1 250 363 6031; E-mail: wkurz@nrcan.gc.ca


[2] Stem cells: Test-tube recipe makes functioning heart cells (AOP)
DOI: 10.1038/nature06894

***This paper will be published electronically on Nature's website on 23 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 24 April, but at a later date. ***

A US and British research team has successfully grown three types of human heart cells from cultures derived from embryonic stem cells. The achievement is another step towards the test-tube creation of functioning heart tissue for transplants.

Researchers led by Gordon Keller created the cells by supplying embryonic stem cell cultures with a cocktail of growth factors and other molecules involved in development. By supplying the right growth factors at the right time during development, they encouraged the cells to grow into ‘progenitors’ of three different types of cardiac cell, called cardiomyocytes, endothelial cells and vascular smooth muscle cells — each an important constituent of functioning heart muscle.

As Keller and colleagues describe in this week’s Nature, these three cell types could be individually produced by isolating particular types of progenitors, which will help researchers to understand heart development in more detail. What’s more, when the team transplanted a mixture of the three cell types into mice with simulated heart disease, their heart function was significantly improved, offering hope to those aiming to develop this technique for treating human hearts.

CONTACT

Gordon Keller (McEwen Centre for Regenerative Medicine, Toronto, ON, Canada)
Tel: +1 416 581 7694; E-mail: gkeller@uhnresearch.ca


[3] Black holes: Seeing the light (pp 966-969; N&V)

Scientists are one step closer to visualizing the processes occurring at supermassive black holes, which are thought to be at the rotational centre of most galaxies, and which somewhat counter-intuitively emit copious amounts of light as they accrete gas and dust from their surroundings. A paper in this week’s Nature reveals for the first time the structures inside a plasma jet emanating from a supermassive black hole or ‘active galactic nucleus’, and resolves the long-standing mystery of how these jets are formed.

A ‘blazar’ is a particular type of active galactic nucleus, which possesses a pair of plasma jets streaming from the accreting black hole at near-light speeds. These jets have been modelled, but until now scientists have been unable to locate their precise origin or picture exactly how they are formed.

Alan P. Marscher and colleagues report sequences of high-resolution radio images and optical polarization measurements of the blazar known as ‘BL Lacertae’. The data reveal a bright feature in the jet that causes a double flare of radiation at different wavelengths. The authors are able to verify that the jet starts in a region with a twisting, helical magnetic field and locate the initial activity within the zone where the jet is accelerated and focused.

CONTACT
Alan Marscher (Boston University, MA , USA)
Tel: +1 617 353 5029; E-mail: marscher@bu.edu

David Meier (California Institute of Technology, Pasadena, CA, USA) N&V author
Tel: +1 818 354 3074; E-mail: dlm@sgra.jpl.nasa.gov


[4] Vision: Seeing is not behaving (AOP)
DOI: 10.1038/nature06829

***This paper will be published electronically on Nature's website on 23 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 24 April, but at a later date. ***

The ability to ‘see’ images can be separated from other modes of light detection, according to research in Nature this week. The work may have implications for people with troubled sleep or seasonal depression, suggesting that they could benefit from light detection and melatonin suppression tests even if they have normal sight.

Retinal rods and cones are photosensitive nerve cells needed not only for pattern vision but also for non-image-forming light detection processes such as the pupillary reflex — controlling the amount of light let into the eye — and circadian rhythm regulation.

Samer Hattar and colleagues genetically removed intrinsically photosensitive retinal ganglion cells — one of several cell types receiving input from rods and cones in mice. They observed that the mice retained their pattern vision but showed deficits in photoentrainment — the ability to train circadian rhythms to external light — and pupillary light reflex. This illustrates that there are two distinct pathways for the two different aspects of light detection.

CONTACT
Samer Hattar (Johns Hopkins University, Baltimore, MD, USA)
Tel: +1 410 516 4231; E-mail: shattar@jhu.edu

[5] Palaeoclimate: Linking events across a key climate transition (pp 979-982)

The Earth experienced a dramatic climate transition some 34 million years ago, when the Antarctic underwent extraordinarily rapid glaciation. A paper in this week's Nature looks into the connection between this glaciation and a deepening of the calcite compensation depth — the ocean depth at which the rate of calcium carbonate input from surface waters equals the rate of dissolution.

Agostino Merico and colleagues used a global model to test competing ideas put forward to explain the events triggering the climate transition. These include an increase in organic carbon burial rates, an increase in weathering of silicate rock, an increase in global siliceous (versus calcareous) plankton export production and a shift of global calcium carbonate sedimentation from shelf to deep ocean basins.

The researchers found that a drop in sea level — with a shift in calcium carbonate partitioning between the ocean shelf and the deep sea — could best explain the link between the deepening of the calcite compensation depth and the Antarctic glaciation.

CONTACT

Agostino Merico (GKSS Research Centre, Geesthacht, Germany)
Tel: +49 4152 871 502; E-mail: agostino.merico@gkss.de


[6] Superconductivity: Does a kink hold the key? (pp 975-978)

Even after two decades of investigation, it is still a mystery how some copper oxide compounds can become superconducting at relatively high temperatures. A paper in this week’s Nature rules out one possible explanation.

Steven Louie and colleagues home in on an anomalous kink — hoped to hold the key to the problem — that appears under certain conditions in the photoemission spectrum of a lanthanum–strontium derivative of copper oxide nicknamed LSCO. This kink has been attributed to interactions between electrons and bosons — either phonons or spin fluctuations — in the material. The team’s calculations within the conventional formalism now rule out the possibility of a phonon contribution. The kink must therefore be explained by other effects, such as spin excitations or novel phonon mechanisms. Researchers have focused on the kink anomaly in the belief that it may hold the key to understanding high-temperature superconductivity.

CONTACT

Steven Louie (University of California at Berkeley, CA, USA)
Tel: +1 510 642 1709; E-mail: sglouie@berkeley.edu


[7] And finally… Inside the DNA of a tropical fruit tree (pp 991-996)

Papayas are not just exotic fruits with nutritional and medicinal benefits, they are also model plants for studying genetics and evolution. A paper in this week’s Nature reports a draft DNA sequence of its whole genome and brings some interesting features to light.

Maqsudul Alam and a collaboration of scientists from around the world have produced a genome assembly for ‘SunUp’, a genetically engineered and commercially produced fruit tree that is virus resistant. Comparing the genome sequence with that of a distant relative, the grass Arabidopsis, the authors find that the papaya genome is three times larger but in fact contains fewer genes — which could provide clues about the evolution of seed-producing plants. The sequence contains features that offer insight into the plant’s adaptation to day length in the tropics, and into how it attracts seed-dispersal agents and creates the volatile compounds responsible for its delicious flavour.

CONTACT
Maqsudul Alam (University of Hawaii, Honolulu, HI, USA)
Tel: +1 808 956 0924; E-mail: alam@hawaii.edu

Shaobin Hou (University of Hawaii, Honolulu, HI, USA) Additional author contact
Tel: +1 808 956 0924; E-mail: shaobin@hawaii.edu

Margy Yuen (University of Hawaii, Honolulu, HI, USA) Media contact
Tel: +1 808 956 0924; E-mail: asgpb@hawaii.edu

ALSO IN THIS ISSUE…

[8] Crystal structures of DNA/RNA repair enzymes AlkB and ABH2 bound to dsDNA (pp 961-965)

[9] A topological Dirac insulator in a quantum spin Hall phase (pp 970-974)

[10] Hydrous silicate melt at high pressure (pp 983-986)


ADVANCE ONLINE PUBLICATION

***These papers will be published electronically on Nature's website on 23 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 24 April, but at a later date. ***

[11] NF-kB links innate immunity to the hypoxic response through transcriptional regulation of HIF-1a
DOI: 10.1038/nature06905

[12] Draper-dependent glial phagocytic activity is mediated by Src and Syk family kinase signaling
DOI: 10.1038/nature06901

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.

CANADA:
Toronto: 2
Victoria: 1

CHINA
Tianjin: 7

FINLAND
Kylmala: 3
Piikkio: 3
Turku: 3

GEORGIA
Abastumani: 3

GERMANY
Geesthacht: 5

ITALY
Perugia: 3

RUSSIA
St Petersburg: 3

UNITED KINGDOM
Cardiff: 3
London: 2, 10
Manchester: 4
Oxford: 4
Southampton: 3, 5

UNITED STATES OF AMERICA

Arizona
Tucson: 3

California
Berkeley: 3, 6, 7
Davis: 7
Foster City: 7
La Jolla: 11
San Francisco: 2

Connecticut
New Haven: 10

Georgia
Athens: 7
Atlanta: 3

Hawaii
Aiea: 7
Hilo: 7
Honolulu: 7
Kihei: 7
Pearl City: 7

Illinois
Chicago: 8
Urbana: 7

Indiana
Bloomington: 7
Indianapolis: 2

Louisiana
Baton Rouge: 10

Maryland
Baltimore: 4
College Park: 7
Rockville: 7

Massachusetts
Boston: 3
Worcester: 12

Michigan
Ann Arbor: 3
East Lansing: 7

New Jersey
Piscataway: 7
Princeton: 9

New York
Bronx: 12
New York: 2

North Carolina
Durham: 7

Pennsylvania
University Park: 7

Rhode Island
Providence: 4

Tennessee
Memphis: 7

Texas
College Station: 7

Wisconsin
Madison: 7

PRESS CONTACTS…

For North America and Canada
Katie McGoldrick, Nature Washington
Tel: +1 202 737 2355; E-mail: k.mcgoldrick@naturedc.com

For Japan, Korea, China, Singapore and Taiwan
Mika Nakano, Nature Tokyo
Tel: +81 3 3267 8751; E-mail: m.nakano@natureasia.com

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

About NPG

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Keywords associated to this article: Climate, Stem cells, Black holes, Vision, Palaeoclimate, Superconductivity, DNA, tropical fruit tree
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