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This press release is copyright Nature.
VOL.438 NO.7067 DATED 24 NOVEMBER 2005
This press release contains:
* Summaries of newsworthy papers:
* Bacterial engineering: E. coli sees the light
* Biology: Building a case for synthetic biology
* Infectious disease: siRNA-based microbicide stops herpes
* Epidemiology: small group attracts most malarial bites
* Neurobiology: For the brain, less is more
* Condensed matter physics: Time to rethink the pseudogap
* Astronomy: Magnetic field spied inside star's disk
* Systems biology: How cells stay calm inside when it's chaotic outside
* Immunology: In (self) defence of sea squirts
* And finally... Stop in their tracks
* Mention of papers to be published at the same time with the same embargo
* Papers to be published online (AOP)
* Geographical listing of authors
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[1] Bacterial engineering: E. coli sees the light (pp441-442)
Scientists have created a 'living photographic film' made of bacteria. The
system consists of a flat mat of bacteria in which the bacterial cells have
been engineered to produce pigment unless exposed to light, allowing
high-resolution, black-and-white images to be rendered by these living
organisms.
The tiny size of bacterial cells allows the film to achieve tremendously
high resolution - up to 100 megapixels per square inch, say Christopher
Voigt and colleagues, who unveil the system in a Brief Communication in this
week's Nature. They created the film by taking a light-sensing gene from a
photosynthetic microorganism called a cyanobacterium and - via genetic
engineering - transferring it into the cell membranes of the bacterium
Escherichia coli.
These bacteria also carry a gene called lacZ, which produces a black
pigment. But this is connected to the light-sensing gene in such a way that
exposure to light shuts off pigment production, meaning that black-and-white
images can be 'stencilled' onto the mat of bacteria. The authors add that
the technology could also be used to study how bacteria use gene expression
to send signals to one another.
CONTACT
Christopher Voigt (University of California at San Francisco, CA, USA)
Tel: +1 415 502 7050; E-mail: [email protected]
[2] & [3] Biology: Building a case for synthetic biology (pp443-448 &
449-453)
Scientists in the rapidly growing field of 'synthetic biology' advocate
using a reconstructive approach to puzzle together nature's mysteries. In a
review article by Michael Elowitz and David Sprinzak, appearing in this
week's Nature, the authors discuss how synthetic biology could enable us to
better understand genetic pathways. Just as reassembling a clock helps to
illustrate how the device works, building minimal models of gene circuits
from scratch can shed light on biological systems.
In a second review article, also appearing this week in Nature, Drew Endy
elaborates on the idea that synthetic biology is an engineering technology
based on living systems. The author aims to describe the foundations for an
approach that may be used to specify form and function to every piece of DNA
that would eventually result in the building of a biological
system.
CONTACT
Michael Elowitz (California Institute of Technology, Pasadena, CA, USA)
paper no: [2]
Tel: +1 626 395 8871; E-mail: [email protected]
Drew Endy (Massachusetts Institute of Technology, Cambridge, MA, USA) paper
no: [3]
Tel: +1 617 258 5152; E-mail: [email protected]
[4] Infectious disease: siRNA-based microbicide stops herpes (DOI:
10.1038/nature04263)
***This paper will be published electronically on Nature's website on 23
November 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 November, but at a later date.***
Scientists have developed a microbicide that protects mice against the
lethal genital herpesvirus (HSV-2). The approach, described in a paper
published online this week by Nature, relies on RNA interference (RNAi) to
disrupt both infection by and replication of the virus. Judy Lieberman and
her colleagues show that in mice, vaginal delivery of small interfering RNAs
(siRNAs) against two of the viral genes protects the mice against HSV
infection for six days. Notably, the siRNAs did not cause an inflammatory
response, showed an effect when administered after, as well as before,
infection, and were required in amounts that would have a realistic cost if
translated to humans.
The team point out that future therapies blocking HSV in humans
could help curb the spread of HIV, as HSV-2 infection assists HIV
transmission.
CONTACT
Judy Lieberman (The CBR Institute for Biomedical Research, Harvard Medical
School, Boston, MA, USA)
Tel: +1 617 278 3106; E-mail: [email protected]
[5] Epidemiology: small group attracts most malarial bites (pp492-495)
The prevalence of malaria in African communities is not evenly spread
between individuals, according to a mathematical study published in this
week's Nature. Rather than people being at equal risk of infection, the
analysis shows that around 20% of people receive some 80% of infectious
mosquito bites. Targeting those people who are bitten most may therefore
help to maximize the impact of anti-malaria initiatives.
David Smith and his colleagues set out to determine the relationship between
'parasite ratio' - the proportion of people infected with the malaria
pathogen, Plasmodium falciparum - and 'entomological inoculation rate', the
rate at which people are bitten by infectious mosquitoes. By analysing data
previously collected from some 90 African villages, they discovered that
this relationship is highly skewed, so that relatively few individuals
receive most of the infections.
The results also show that a single bout of malaria is not enough to confer
immunity thereafter, and that repeated infections in childhood are necessary
for such immunity to arise. Because of this, and the skewed relationship
between parasite ratio and inoculation rate, a halving of the rate of
infectious bites will result in only a 4% drop in the proportion of people
infected. However, the authors add, identifying those most at risk of
infectious bites could show where best to target public-health efforts.
CONTACT
David Smith (Fogarty International Center, National Institute of Health,
Bethesda, MD, USA)
Tel: +1 301 496 1932; Email: [email protected]
To arrange interviews with David Smith please contact:
John Makulowich, Communications Director (Fogarty International Center,
National Institute of Health, Bethesda, MD, USA)
Tel: +1 301 402 8614, Cell: +1 301 728 4702; E-mail: [email protected]
[6] Neurobiology: For the brain, less is more (pp500-503)
Our visual short-term memory has a very limited capacity: despite the
presence of numerous objects in our environment, our awareness is limited to
only a few objects at any given time. A new study appearing in this week's
Nature suggests that, in a visual task, the fewer irrelevant items you keep
in mind, the more capacity you have for remembering the important things.
Edward Vogel and his colleagues showed college students a screen with
coloured dots, and compared their ability to remember what they saw in the
presence or absence of distractor dots. By recording the subjects'
performance and looking at brain activity, the scientists discovered that
people who kept the irrelevant distractor objects in mind were less
efficient at remembering relevant objects than those who were more
selective. The authors found that this selection efficiency varies
substantially from person to person, but that they could use a subject's
visual memory capacity as a good predictor of their filtering ability.
CONTACT
Edward Vogel (University of Oregon, Eugene, OR, USA)
Tel: +1 541 346 4905; E-mail: [email protected]
[7] Condensed matter physics: Time to rethink the pseudogap (pp474-478; N&V)
A surprise finding has linked the physics of two of the most important
classes of materials in condensed matter physics. The paper appears in this
week's Nature but seems to raise more questions than answers.
High-temperature copper-oxide superconductors possess a puzzling feature -
the so-called 'pseudogap' - reflecting the fact that electronic excitations
are different along different directions of the crystal lattice. Until now,
the pseudogap had only been seen in superconductors, and physicists
therefore assumed that it was intimately linked to superconductivity.
But now, Zhi-xun Shen and colleagues have discovered a pseudogap state in a
magnetic manganite compound - a material that is very different from a
superconductor. By shining photons of light at the manganite, the team were
able to map very accurately the energy and momentum of electrons within the
solid. They found, rather surprisingly, that even in manganite - where
electrons are expected to move around easily because of its metallic nature
- the electron movement is strongly tied to the motion of the crystal
lattice. Ultimately this interaction gives rise to the pseudogap.
This now raises the question: how important is the pseudogap for the
high-temperature superconductors? Physicists may need to rejig their ideas.
A related News & Views article by Peter Littlewood and Simon Kos accompanies
this paper.
CONTACT
Zhi-xun Shen (Stanford University, CA, USA)
Tel: +1 650 725 8254; E-mail: [email protected]
Peter Littlewood (University of Cambridge, UK)
Tel: +44 1223 339 991; E-mail: [email protected]
[8] Astronomy: Magnetic field spied inside star's disk (pp466-469)
The magnetic field inside a growing star's dusty disk, close to the star
itself, has been detected, according to research in this week's Nature.
Young stars can put on weight by consuming material from an accretion disk.
The magnetic field inside this disk helps to slow its rotation, causing
material to fall towards the central star. Although theoretical models
predict this crucial role, the magnetic field close to the star has not
hitherto been directly measured.
Jean-François Donati and colleagues used the ESPaDOnS instrument at the
Canada-France-Hawaii Telescope atop Mauna Kea to study visible light coming
from the FU Orionis system, which contains a young star that is being fed by
a surrounding disk.
Light from FU Orionis is rotated, or polarized, by magnetic fields in the
disk. By measuring this polarization, the astronomers found that the
magnetic field slows down the disk material much more than models predict.
This may explain why the star does not spray out some of the infalling
material as a jet, a feature seen in other star-disk systems.
CONTACT
Jean-François Donati (Observatoire Midi-Pyrénées, Toulouse, France)
Tel: +33 561 332 917, E-mail: [email protected]
[9] Systems biology: How cells stay calm inside when it's chaotic outside
(pp504-507)
Cells have to respond to vastly different environmental signals in a
reliable way. They integrate highly variable inputs on the cell surface into
more exact outputs inside the cell to turn on genes or molecular machines.
This ability to interpret such fluctuations into a defined series of outputs
is termed robustness.
Markus Kollmann and colleagues studied how the bacterium Escherichia
coli achieves such robustness when it turns on its flagellum to move towards
attractive nutrients. They measured changes in the levels of the proteins
involved in this process between different bacterial strains and performed
computer simulations to determine what type of regulatory network the
bacteria need to respond reliably under these varying conditions.
The bacteria, they find, have evolved the simplest possible network
that can provide a robust response in virtually all cells. Similarly economical
networks may be found in other cells including, human cells.
CONTACT
Markus Kollmann (University of Freiburg, Germany)
Tel: +49 761 203 5828, E-mail: [email protected]
[10] Immunology: In (self) defence of sea squirts (pp454-459; N&V)
All animals need to be able to distinguish their own cells from those of
others, such as invading pathogens. In vertebrates, this is achieved by a
set of genes called the major histocompatibility complex (MHC), but this
mechanism of 'histocompatibility' has not been described in non-vertebrate
animals. Scientists have now discovered the first gene that carries out this
function in an invertebrate organism.
A team of researchers, led by Anthony De Tomaso, studied a DNA sequence
called FuHC in the sea squirt Botryllus schlosseri. This organism forms
colonies of genetically identical individuals with a common circulatory
system - where two colonies are expanding side by side, they must therefore
be able to distinguish members of their own colony from those of the
neighbouring one.
As the researchers report in this week's Nature, this recognition depends on
the FuHC gene, which produces one of a range of 'immunoglobulin' proteins
similar to those encoded by the vertebrate MHC locus. This suggests that the
evolutionary roots of histocompatibility extend throughout a wide range of
lineages stretching far into the past. This process may even have been
crucial in shaping the gene pools of some of our earliest ancestors, adds
Gary Litman in an accompanying News and Views article.
CONTACT
Anthony De Tomaso (Stanford University, Pacific Grove, CA, USA)
Tel: +1 831 655 6218, E-mail: [email protected]
Gary Litman (University of South Florida, St. Petersburg, FL, USA)
Tel: +1 727 553 3601, E-mail: [email protected]
[11] And finally... Stop in their tracks (p442)
Foraging ants have evolved a clever 'stop' sign to inform their nestmates of
unrewarding paths according to a Brief Communication in this week's Nature.
Researchers have long known that ants communicate via attractive trail
pheromones, leading their fellow ants to food or water. But this research
shows that they use opposing signals to warn of barren trails.
Elva J. H. Robinson and colleagues show that Pharaoh's ants use a
system that includes negative, repellent pheromones with signals
concentrated at decision points - where trails fork.
Exactly how this encourages foraging efficiency is not known. The authors
argue that negative pheromones may complement positive ones or could help
ants to escape from an unnecessarily long route to food that is being
reinforced by attractive signals.
CONTACT
Elva J. H. Robinson (Sheffield University, UK)
Tel: +44 114 222 0149; E-mail: [email protected]
ALSO IN THIS ISSUE...
[12] Experimental implementation of heat-bath algorithmic cooling using
solid-state nuclear magnetic resonance (pp470-473; N&V)
[13] Probing carrier dynamics in nanostructures by picosecond
cathodoluminescence (pp479-482)
[14] Impacts of orbital forcing and atmospheric carbon dioxide on Miocene
ice-sheet expansion (pp483-487)
[15] Density of hydrous silicate melt at the conditions of Earth's deep
upper mantle (pp488-491)
[16] Spatial regulation of b-actin translation by Src-dependent
phosphorylation of ZBP1 (pp512-515; N&V)
[17] Structures of ParB bound to DNA reveal mechanism of partition
complex formation (pp516-519)
[18] An induced-fit mechanism to promote peptide bond formation and
exclude hydrolysis of peptidyl-tRNA (pp520-524)
ADVANCE ONLINE PUBLICATION
***These papers will be published electronically on Nature's website on 23
November 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 November, but at a later date.***
[19] Critical role of TRAF3 in the Toll-like receptordependent and
independent antiviral response
(DOI: 10.1038/nature04374)
[20] Specificity in Toll-like receptor signalling through distinct
effector functions of TRAF3 and TRAF6
(DOI: 01.1038/nature04369)
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: 17
Waterloo: 7, 12
DENMARK
Odense: 20
FRANCE
Grenoble: 8
Toulouse: 8
GERMANY
Bremen: 14
Freiburg: 9
Halle: 16
Heidelberg: 9
Kiel: 14
Munich: 20
JAPAN
Ibaraki: 15
Mito: 15
Tokyo: 7
Tsukuba: 7
KENYA
Nairobi: 5
THE NETHERLANDS
Leiden: 7
SWITZERLAND
Lausanne: 13
UNITED KINGDOM
Oxford: 5
Sheffield: 11
UNITED STATES OF AMERICA
California
Berkeley: 1, 7
La Jolla: 20
Los Angeles: 19
Pacific Grove: 10
Pasadena: 2
San Francisco: 1
Stanford: 7, 10
Connecticut
New Haven: 15, 18
Illinois
Argonne: 7
Maryland
Bethesda: 5
Massachusetts
Boston: 4
Cambridge: 3
New Jersey
Princeton: 5
New York
Bronx: 16
Oregon
Eugene: 6
Portland: 17
Tennessee
Memphis: 20
Texas
Austin: 1
Houston: 17
PRESS CONTACTS...
For North America and Canada
Katie McGoldrick, Nature Washington
Tel: +1 202 737 2355; E-mail: [email protected]
<mailto:[email protected]>
For Japan, Korea, China, Singapore and Taiwan
Rinoko Asami, Nature Tokyo
Tel: +81 3 3267 8751; E-mail: [email protected]
<mailto:[email protected]>
For the UK/Europe/other countries not listed above
Ruth Francis, Nature London
Tel: +44 20 7843 4562; E-mail [email protected]
<mailto:[email protected]>
Katharine Mansell, Nature London
Tel: +44 20 7843 4658; E-mail: [email protected]
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