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This press release is copyright Nature. VOL.441 NO.7091 DATED 18 MAY 2006
This press release contains:
· Summaries of newsworthy papers:
Medicine: Novel antibiotic fights hospital killers
Evolution: Human and chimp ancestors may have interbred after evolutionary split
Astronomy: Star is the parent of three middleweights
Genetics: Chromosome 1 completes the set
Astronomy: Dwarf galaxy formation prevented by reionization
Evolution: Single mutation changes cheats into model citizens
Plant development: 'Living fossil' gives clue to first flowering plants
Optoelectronics: A short story of LEDs
Microbiology: Can't live, if living is without you
And finally… Monkey codewords
· Mention of papers to be published at the same time with the same embargo
· Geographical listing of authors
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[1] Medicine: Novel antibiotic fights hospital killers (pp 358-361; N&V)
In a much-needed blow against rising antibiotic resistance, a team led by Jun Wang report in this week’s Nature that it has discovered a potent natural antibiotic that kills many Gram-positive bacteria, including some of the biggest hospital threats: methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE).
The researchers screened 250,000 natural product extracts in whole-cell and biochemical assays, and hit upon platensimycin, a small molecule manufactured by a strain of Streptomyces platensis from a South African soil sample.
Platensimycin, which represents a previously unknown class of antibiotics, acts by blocking enzymes involved in the synthesis of fatty acids, the building blocks of lipids. No existing antibiotics target fatty-acid synthesis in this way. The antibiotic clears mice of S. aureus infection and does not appear to cause toxic side effects.
CONTACT
Marjorie Moeling (Director, Merck Research Laboratories Communications & Policy)
Tel: +1 215 652 1467; E-mail: [email protected]
Eric D. Brown (McMaster University, Hamilton, Canada)
Tel: +1 905 525 9140 x22392; E-mail: [email protected]
[2] Evolution: Human and chimp ancestors may have interbred after evolutionary split (AOP)
DOI: 10.1038/nature04789
***This paper will be published electronically on Nature's website on 17 May 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 18 May, but at a later date.***
The evolutionary split between the ancestors of modern humans and chimpanzees occurred more recently - and was far more complex - than previously thought, as indicated by a rigorous comparison of our respective genetic sequences. The analysis shows a wide spread of divergences between modern human and chimp genetic sequences.
The study, led by David Reich and reported in this week's Nature suggests that after the hominin and chimp lineages initially split, more than 6.3 million years ago, they exchanged genes before a final split more recently. The interval between initial and final split could have been as long as 4 million years.
This research calls into question the status as hominins of early fossils such as Toumaï (Sahelanthropus tchadensis) and Millennium Man (Orrorin tugenensis), which date from this interval. But the split itself was far from simple - different regions of the genomes show huge variation in the degree of divergence between human and chimpanzee sequences. The X chromosomes show particular similarity, a fact that could be explained by the theory that the two lineages re-hybridized with one another thousands or even millions of years after previously parting company.
CONTACT
David Reich (Harvard Medical School, Boston, MA, USA)
Tel: +1 617 432 6548; E-mail: [email protected]
[3] Astronomy: Star is the parent of three middleweights (pp 305-309; N&V)
An international team of astronomers has discovered a remarkable solar system around a nearby star, consisting of three medium-sized planets each about the same mass as Neptune. They report their findings in Nature this week.
Over 170 extrasolar planets — those outside our own Solar System — have been discovered so far, and among them there are 17 known multi-planet systems. All of those seen previously have included at least one giant planet, about the size of Jupiter. But the new extrasolar system seen by Christophe Lovis and colleagues is different: the largest of the three planets it contains is no more than about 18 times as massive as the Earth, which is about the same as the mass of Neptune. The other two have masses about 10 and 12 times that of the Earth.
These medium-sized planets are orbiting a star called HD 69830, which, at a distance of 41 light years, is barely visible with the naked eye, towards the southern constellation of Puppis. The planets have orbital periods (the time taken to orbit the star) ranging from 8.7 to 197 days. Lovis and colleagues think that the two innermost planets are rocky, rather like Mercury, while the outer one has a gaseous atmosphere surrounding a rocky core. They believe that it lies within the star's habitable zone, in which liquid water — often considered a prerequisite for life — can exist on the planet's surface.
CONTACT
Christophe Lovis (Université de Genève, Sauverny, Switzerland)
Tel : +41 22 379 2407 ; E-mail: [email protected]
David Charbonneau (Harvard University, Cambridge, MA, USA)
Tel: +1 617 496 6515; E-mail: [email protected]
[4] Genetics: Chromosome 1 completes the set (pp 315-321)
This week’s Nature reports the finished DNA sequence of human chromosome 1 — the final human chromosome to be completed and published — along with a detailed annotation of its genes and other features, such as duplicated regions and single nucleotide polymorphisms (SNPs).
Chromosome 1 is the largest of the human chromosomes, containing approximately 8% of all human genetic information. It is packed with 3,141 genes and 991 pseudogenes, report Simon Gregory and his colleagues, making it one of the most gene-dense chromosomes in humans.
Over 350 human diseases are associated with alterations of chromosome 1, and its sequence should help track down those for which the corresponding genes remain unknown. Also, by searching for regions that vary between different populations around the world, the team has identified key spots where natural selection seems to be acting.
CONTACT
Simon Gregory (Duke University, Durham, NC, USA)
Tel: +1 919 684 0726; E-mail: [email protected]
Please note the author is travelling and it may be easier to reach him through
Don Powell (Press Officer, The Wellcome Trust Sanger Institute, Hinxton, UK)
Tel: +44 1223 494 956; E-mail: [email protected]
[5] Astronomy: Dwarf galaxy formation prevented by reionization (pp 322-324)
When the first stars and galaxies formed, their light stripped electrons from neutral gases in the Universe to produce charged ions, a process known as ‘reionization’. Observations now suggest that, in line with current theories, this process suppressed the formation of dwarf galaxies and favoured the growth of more massive collections of stars.
In this week’s Nature, J. Stuart B. Wyithe and Abraham Loeb show that most of the radiation emitted by galaxies immediately after reionization came from relatively large galaxies, hundreds of times bigger than those thought to have caused the reionization.
They predict that future astronomical surveys should detect a population of dwarf galaxies responsible for the reionization that ultimately prevented further dwarf galaxy formation.
CONTACT
Abraham Loeb (Harvard University, Cambridge, MA, USA)
Tel: +1 617 496 6808; E-mail: [email protected]
[6] Evolution: Single mutation changes cheats into model citizens (pp 310-314; N&V)
A single genetic change is enough to completely reform one's character — at least in the soil-dwelling bacterium Myxococcus xanthus. A simple mutation converts these microbes from selfish cheaters to social team players, a discovery that may show how simple changes can underpin the evolution of relatively complex forms of cooperation.
During hard times, M. xanthus forms fruiting bodies composed of hardy spores — a collaborative process that allows resources to be pooled, but which relatively few individuals survive. This system is open to cheating by strains that do not bother to form these aggregations, but nonetheless reap the benefits of the nutrients provided.
But when researchers led by Gregory Velicer mixed the cheating and socially responsible strains together under alternating conditions of stress and plenty, they noticed a surprising result: the strain that ultimately evolved was a cooperative strain that produced more surviving cells than either of the two original strains. And when they sequenced the genetic sequence of the strains, they found that the cheaters' newly found social conscience was due to a single-letter change in the DNA code.
The researchers, reporting in this week’s Nature, christened the new strain Phoenix, because it rescued the bacterial population from the ashes of almost certain doom at the hands of the cheaters. "A virulent cheater that threatens a population will necessarily result in strong natural selection for strategies that can re-evolve sociality in its wake," explains Kevin Foster in an accompanying News and Views article.
CONTACT
Gregory Velicer (Max-Planck Institute for Developmental Biology, Tubingen, Germany)
Tel: +9 70 7160 11462; E-mail: [email protected]
Kevin Foster (Harvard University, Cambridge, MA, USA)
Tel: +1 617 496 5544; E-mail: [email protected]
[7] Plant development: 'Living fossil' gives clue to first flowering plants (pp 337-340)
Flowering plants are found almost everywhere, but their origins are far from understood — Charles Darwin called the problem an "abominable mystery". An analysis of a 'living fossil' species now shows that the very first flowering plants might have arisen during a period of intense evolutionary experimentation.
The discovery, reported by William Friedman in this week's Nature, revolves around the egg sac of Amborella trichopoda, a relic species remaining from an ancient lineage. During development, the female part of this plant's reproductive apparatus, called the embryo sac, has a different number of cells compared with the corresponding structure in most of today's flowering species.
This unsuspected variability suggests that flowering plants may have arisen during a time when plant development was particularly flexible — a situation that may have allowed for the evolution of the seemingly costly business of producing flowers.
CONTACT
William Friedman (University of Colorado, Boulder, CO, USA)
Tel: +1 303 492 3082; E-mail: [email protected]
[8] Optoelectronics: A short story of LEDs (pp 325-328; N&V)
Increasing the data storage density of optical memory devices such as compact disks means making the data spots smaller. This in turn means that the light beams used to read out the data have to have ever-shorter wavelengths. In Nature this week, Yoshitaka Taniyasu and colleagues report a light-emitting diode (LED) with the shortest wavelength of any such device to date, which emits deep into the ultraviolet part of the spectrum.
The research could lead not only to ultraviolet LEDs but to short-wavelength lasers. And these could find applications not just in optical data storage but also in biomedicine and water purification, where for example ultraviolet light is used to burn up hazardous organic matter.
The key to the new LEDs is a material called aluminium nitride (AlN). Although this substance is well known, it has not previously been used in light-emitting devices. To enable that, the researchers had to make two types of semiconducting forms of AlN: one in which electrical current is carried by mobile electrons (called n-type), and one where the carriers are positively charged holes (p-type). This was done by doping the material with atoms of either silicon or magnesium. When these films of n-type and p-type AlN are combined in a sandwich structure, the electrons and holes combine, releasing a photon (light particle) of short-wavelength ultraviolet light.
CONTACT
Yoshitaka Taniyasu (NTT Basic Research Laboratories, Atsugi, Japan)
Tel: +81 46 240 3497; E-mail: [email protected]
Asif Khan (University of South Carolina, Columbia, SC, USA)
Tel: +1 803 777 7941; E-mail: [email protected]
[9] Microbiology: Can't live, if living is without you (pp 345-348)
The beneficial relationship between hydrothermal vent tubeworms and their bacterial symbionts is put under the microscope in Nature this week. Although the adult animals are nutritionally dependent on their bacterial partners, the tubeworm larvae are symbiont-free. Monika Bright and colleagues describe a unique model of symbiont acquisition that resembles pathogenic infection.
It has been previously hypothesized that the bacteria colonize the vent tubeworms through their mouths, and eventually form a structure called the trophosome. However, the extreme pressure conditions of the deep sea in which the tubeworms live makes studying any aspect of their biology particularly difficult. Here, the researchers succeeded by using microscopy on tissue samples to demonstrate that the symbionts in fact colonize their juvenile hosts through active infection of the skin accompanied by massive apoptosis of host tissue. Furthermore, the team shows that the trophosome does not originate from gut-derived structures, but from skin-forming tissue.
The researchers believe that this could lead to a re-examination of accepted hypotheses on the evolution of a variety of symbiotic associations.
CONTACT
Monika Bright (University of Vienna, Austria)
Tel: +43 142 775 4331; E-mail: [email protected]
[10] And finally… Monkey codewords (p 303)
Many animals have a range of distinct calls, but stringing words together to convey a message is thought to be uniquely human. But an African monkey species may also be able to pull off a similar trick — it can also combine different calls to express new meanings.
Putty-nosed monkeys (Cercopithecus nictitans) have two basic call sounds: ‘pyows’, used to warn their group of a loitering leopard; and ‘hacks’, used to alert them to a hovering eagle. But they can also combine these calls into strings consisting of several pyows followed by a few hacks. These ‘sentences’ — recorded by Kate Arnold and Klaus Zuberbühler, and described in a Brief Communication in this week’s Nature — seem to function as a command to the group to move away to safer terrain.
The more complex calls may therefore represent an efficient way to use a restricted repertoire. Rather than creating a new sound, the monkeys can encode fresh information by combining two existing ones.
CONTACT
Klaus Zuberbühler (University of St Andrews, UK)
Tel: +44 1334 462 080; E-mail: [email protected]
ALSO IN THIS ISSUE…
[11] Links between annual, Milankovitch and continuum temperature variability (pp 329-332)
[12] Seismic detection of folded, subducted lithosphere at the core–mantle boundary (pp 333-336)
[13] A keratin cytoskeletal protein regulates protein synthesis and epithelial cell growth (pp 362-365)
[14] The mechanism of cell differentiation in Bacillus subtilis (pp 371-374)
[15] Cleavage of pre-tRNAs by the splicing endonuclease requires a composite active site (pp 375-377)
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
Melbourne: 5
AUSTRIA
Vienna: 9
FRANCE
Marseille: 3
Paris: 3
St Michel l’Observatoire: 3
Verrieres-le-Buisson: 3
GERMANY
Tubingen: 6
JAPAN
Atsugi: 8
PORTUGAL
Aveiro: 3
Evora: 3
Lisbon: 3
SPAIN
Madrid: 1
SWITZERLAND
Bern: 3
Sauverny: 3
UNITED KINGDOM
Hinxton: 4
Little Chesterford: 4
London: 4
Oxford: 4, 14
St Andrews: 10
UNITED STATES OF AMERICA
Arizona
Tempe: 12
California
Santa Cruz: 12
Colorado
Boulder: 7
Florida
Tallahassee: 15
Maryland
Baltimore: 13
Massachusetts
Cambridge: 5
Woods Hole: 11
Minnesota
Minneapolis: 12
New Jersey
Rahway: 1
South Plainfield: 15
North Carolina
Durham: 4
Pennsylvania
University Park: 9
Washington
Seattle: 4
PRESS CONTACTS…
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Katie McGoldrick, Nature Washington
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For Japan, Korea, China, Singapore and Taiwan
Rinoko Asami, Nature Tokyo
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For the UK/Europe/other countries not listed above
Ruth Francis, Nature London
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