Making the paper: Josef Penninger
Nature 462, 388 (2009). doi:10.1038/7272388a
Protein involved in bone breakdown helps regulate body temperature.
Making the paper: Josef Penninger
Nature 462, 388 (2009). doi:10.1038/7272388a
Protein involved in bone breakdown helps regulate body temperature.
Nature 462, 388 (2009). doi:10.1038/7272388b
First authorThat humans use visual information in processing speech is well known, as is the fact that people produce tiny puffs of air when making certain speech sounds. But until now nobody had succeeded in determining whether listeners use the tactile information produced by
Nature 462, 388 (2009). doi:10.1038/7272388c
In the ninth instalment of “The Scientific Tourist in London”, Matt Brown explores the London School of Hygiene and Tropical Medicine (http://network.nature.com/hubs/london/blog/2009/11/12/the-scientific-tourist-in-london-9-famous-men-of-public-health). Built in 1926, the building's art deco elegance “has been tastefully matched with a modern atrium and theatre complex”, writes Brown.
Nature 462, 389 (2009). doi:10.1038/462389a
Japan's effort to make budget allocations by public hearing could be good for the country and for science, but not as currently planned.
Nature 462, 389 (2009). doi:10.1038/462389b
Britain's main opposition party needs policies for research and for universities.
Nature 462, 390 (2009). doi:10.1038/462390a
The US Food and Drug Administration cannot fulfil its mandate without a serious funding boost.
Nature 462, 392 (2009). doi:10.1038/462392a
Nature 462, 392 (2009). doi:10.1038/462392b
Science326, 1100–1103 (2009) 10.1126/science.1179504The collapse of large animal populations, including mammoths and mastodons, in North America may have set off widespread ecosystem changes and occurred before major climatic events that have been put forward as causes of
Nature 462, 392 (2009). doi:10.1038/462392c
Nature 462, 392 (2009). doi:10.1038/462392d
Cell139, 791–801 (2009) 10.1016/j.cell.2009.08.049Little is known about how the body forms the tubing that snakes through many organs. Henrik Semb of Lund University in Sweden and his colleagues tracked pancreas development (pictured) in mice and showed that
Nature 462, 392 (2009). doi:10.1038/462392e
Astrophys. J.706, 1020–1035 (2009) 10.1088/0004-637X/706/2/1020Recent space-based observations of distant galaxies show that many are shining unexpectedly brightly at near-infrared wavelengths.Erin Mentuch of the University of Toronto in Canada and her colleagues say that disks of material
Nature 462, 392 (2009). doi:10.1038/462392f
Nature 462, 393 (2009). doi:10.1038/462393a
J. Cell Biol.187, 513–524 (2009) 10.1083/jcb.200907047When stem cells in the rat testes are at a developmental crossroads, they are able to make their decision independently of their surroundings, according to Zhuoru Wu and her colleagues at the
Nature 462, 393 (2009). doi:10.1038/462393b
J. Neurosci.29, 14484–14495 (2009) 10.1523/JNEUROSCI.1768-09.2009Neuroscientists have generally assumed that there is little difference in how adult rats and mice regulate the generation of new brain cells. But a study by Jason Snyder and his colleagues at the
Nature 462, 393 (2009). doi:10.1038/462393c
Nature 462, 393 (2009). doi:10.1038/462393d
Nature 462, 393 (2009). doi:10.1038/462393e
Author: Philippe Ciais
A geoscientist is astounded by Earth's huge frozen carbon deposits.I believe that the vulnerability of soil carbon to warming is one of the largest sources of uncertainty in the projection of future climate change. If, in a warmer world, bacteria decompose organic soil matter
Nature 462, 411 (2009). doi:10.1038/462411a
Author: Kevan A. C. Martin
As someone who has spent the past 25 years charting brain circuits, I am baffled by the view expressed in your Technology Feature that “sadly, ... pretty much” nothing has happened in my field since the early 1980s (Nature461, 1149–1152
Nature 462, 411 (2009). doi:10.1038/462411b
Author: R. J. Berry
The Church in England did not generally react so “badly” to Darwin's ideas as readers of your Editorial may be led to believe (Nature461, 1173–1174; 10.1038/4611173b2009).Reverend Charles Kingsley, Regius Professor at the University of Cambridge, UK,
Nature 462, 411 (2009). doi:10.1038/462411c
Author: David J. Hill
You question in an Editorial the determination of death for organ-transplant purposes in the United States, where explantation can go ahead once all functions of the entire brain have irreversibly ceased (
Nature 462, 411 (2009). doi:10.1038/462411d
Author: Sergio U. Dani
The pessimism expressed in your Naturejobs feature about the prospects for life sciences in Brazil is justified (Nature461, 1308–1309; 2009). Unfortunately, the country's science enterprise depends as much on its societal values as on its booming economy and wealth of natural
Nature 462, 412 (2009). doi:10.1038/462412a
Author: Paul Arthur Berkman
Lessons are still being learnt from the Antarctic Treaty, adopted 50 years ago this week. It set a visionary precedent for governing regions and resources beyond national jurisdictions, says Paul Arthur Berkman.
Nature 462, 414 (2009). doi:10.1038/462414a
Author: Henner Busemann
Henner Busemann enjoys a hymn to the passionate collectors who fuelled the science of meteorites.
Nature 462, 415 (2009). doi:10.1038/462415a
Author: Devorah Bennu
In the United States, earning a bachelor's degree is recognized as the most important factor for reducing economic inequality and increasing social mobility. But since the mid-1970s, university graduation rates have stagnated and disparities in educational outcomes have risen both among ethnic minorities and among
Nature 462, 416 (2009). doi:10.1038/462416a
Author: Philip Ball
When asked what his Third Symphony meant, Ludwig van Beethoven is said to have sat down at the piano and begun playing it. Analogously, a physicist might write down Erwin Schrödinger's wave equation as an 'explanation' of quantum theory. But even this formula was Schrödinger's
Nature 462, 417 (2009). doi:10.1038/462417a
Authors: Nicholas K. Dulvy & John D. Reynolds
The common skate is not at all common: this large marine fish has 'critically endangered' status. That it turns out to be not one species, but two, is a sharp reminder that good taxonomy must underpin conservation.
Nature 462, 418 (2009). doi:10.1038/462418a
Authors: Thomas Gebhardt & Francis R. Carbone
Killer T cells were thought to patrol the body unhindered, freely gaining access to sites of infection. But it seems that, at least in some body tissues, helper T cells must pave the way for killer T-cell entry.
Nature 462, 419 (2009). doi:10.1038/462419a
Authors: Michael E. Flatté
Electrical injection and detection of spin-polarized electrons in a silicon chip have now been demonstrated at room temperature, paving the way to the development of low-power semiconductor spintronics circuitry.
Nature 462, 420 (2009). doi:10.1038/462420a
Authors: Anthony G. Lee
When it comes to proteins and their environments, opposites repel. So how is the highly charged, polar helix of a transmembrane ion channel accommodated by a non-polar membrane? Easily, if the charges are buried.
Nature 462, 421 (2009). doi:10.1038/462421a
Authors: Judith G. Cohen
Observations of star clusters in the Milky Way defy the view that the constituents of these systems are almost invariably chemically alike. The outlying clusters could be the tattered relics of once larger systems.
Nature 462, 422 (2009). doi:10.1038/462422a
50 Years agoThe appearance of Radiocarbon Supplement Vol. 1 of the American Journal of Science marks an important step forward in the publication of radiocarbon dates. In the past, date lists have appeared at irregular intervals in a number of journals, making it
Nature 462, 423 (2009). doi:10.1038/462423a
Authors: Thoru Pederson
Trailblazer in the study of protein synthesis.
Nature 462, 425 (2009). doi:10.1038/462425a
Authors: Rosamund Daw & Stefano Tonzani
Biomaterials research has come of age. Since antiquity, humans have been taking whatever substances are at hand — natural materials, glass, metals or polymers — and using them to replace body parts that have been damaged by disease or injury. But it is only recently,
Nature 462, 426 (2009). doi:10.1038/nature08601
Authors: Nathaniel Huebsch & David J. Mooney
Biomaterials, traditionally defined as materials used in medical devices, have been used since antiquity, but recently their degree of sophistication has increased significantly. Biomaterials made today are routinely information rich and incorporate biologically active components derived from nature. In the future, biomaterials will assume an
Nature 462, 433 (2009). doi:10.1038/nature08602
Authors: Matthias P. Lutolf, Penney M. Gilbert & Helen M. Blau
Proper tissue function and regeneration rely on robust spatial and temporal control of biophysical and biochemical microenvironmental cues through mechanisms that remain poorly understood. Biomaterials are rapidly being developed to display and deliver stem-cell-regulatory signals in a precise and near-physiological fashion, and serve as powerful
Nature 462, 442 (2009). doi:10.1038/nature08603
Authors: Peter Fratzl & Friedrich G. Barth
Living organisms use composite materials for various functions, such as mechanical support, protection, motility and the sensing of signals. Although the individual components of these materials may have poor mechanical qualities, they form composites of polymers and minerals with a remarkable variety of functional properties.
Nature 462, 449 (2009). doi:10.1038/nature08604
Authors: Jeffrey A. Hubbell, Susan N. Thomas & Melody A. Swartz
The engineering of materials that can modulate the immune system is an emerging field that is developing alongside immunology. For therapeutic ends such as vaccine development, materials are now being engineered to deliver antigens through specific intracellular pathways, allowing better control of the way in
Nature 462, 461 (2009). doi:10.1038/nature08605
Authors: David A. Giljohann & Chad A. Mirkin
The promise of point-of-care medical diagnostics — tests that can be carried out at the site of patient care — is enormous, bringing the benefits of fast and reliable testing and allowing rapid decisions on the course of treatment to be made. To this end,
Nature 462, 467 (2009). doi:10.1038/nature08610
Authors: Yi Wang, Yongjian Huang, Jiawei Wang, Chao Cheng, Weijiao Huang, Peilong Lu, Ya-Nan Xu, Pengye Wang, Nieng Yan & Yigong Shi
FocA is a representative member of the formate–nitrite transporter family, which transports short-chain acids in bacteria, archaea, fungi, algae and parasites. The structure and transport mechanism of the formate–nitrite transporter family remain unknown. Here we report the crystal structure of Escherichia coli FocA at
Nature 462, 473 (2009). doi:10.1038/nature08542
Authors: Dmitriy Krepkiy, Mihaela Mihailescu, J. Alfredo Freites, Eric V. Schow, David L. Worcester, Klaus Gawrisch, Douglas J. Tobias, Stephen H. White & Kenton J. Swartz
Despite the growing number of atomic-resolution membrane protein structures, direct structural information about proteins in their native membrane environment is scarce. This problem is particularly relevant in the case of the highly charged S1–S4 voltage-sensing domains responsible for nerve impulses, where interactions with the lipid
Nature 462, 480 (2009). doi:10.1038/nature08565
Authors: Jae-Woo Lee, Young-Woon Kang, Jina Lee & Young-Wook Lee
The most massive globular cluster in the Milky Way, ω Centauri, is thought to be the remaining core of a disrupted dwarf galaxy, as expected within the model of hierarchical merging. It contains several stellar populations having different heavy elemental abundances supplied by supernovae—a process known as metal enrichment. Although M 22 appears to be similar to ω Cen, other peculiar globular clusters do not. Therefore ω Cen and M 22 are viewed as exceptional, and the presence of chemical inhomogeneities in other clusters is seen as ‘pollution’ from the intermediate-mass asymptotic-giant-branch stars expected in normal globular clusters. Here we report Ca abundances for seven globular clusters and compare them to ω Cen. Calcium and other heavy elements can only be supplied through numerous supernovae explosions of massive stars in these stellar systems, but the gravitational potentials of the present-day clusters cannot preserve most of the ejecta from such explosions. We conclude that these globular clusters, like ω Cen, are most probably the relics of more massive primeval dwarf galaxies that merged and disrupted to form the proto-Galaxy.
Nature 462, 483 (2009). doi:10.1038/nature08581
Authors: F. R. Ferraro, E. Dalessandro, A. Mucciarelli, G. Beccari, R. M. Rich, L. Origlia, B. Lanzoni, R. T. Rood, E. Valenti, M. Bellazzini, S. M. Ransom & G. Cocozza
Globular star clusters are compact and massive stellar systems old enough to have witnessed the entire history of our Galaxy, the Milky Way. Although recent results suggest that their formation may have been more complex than previously thought, they still are the best approximation to a stellar population formed over a relatively short timescale (less than 1 Gyr) and with virtually no dispersion in the iron content. Indeed, only one cluster-like system (ω Centauri) in the Galactic halo is known to have multiple stellar populations with a significant spread in iron abundance and age. Similar findings in the Galactic bulge have been hampered by the obscuration arising from thick and varying layers of interstellar dust. Here we report that Terzan 5, a globular-cluster-like system in the Galactic bulge, has two stellar populations with different iron contents and ages. Terzan 5 could be the surviving remnant of one of the primordial building blocks that are thought to merge and form galaxy bulges.
Nature 462, 487 (2009). doi:10.1038/nature08566
Authors: Y. Kozuka, M. Kim, C. Bell, B. G. Kim, Y. Hikita & H. Y. Hwang
Semiconductor heterostructures provide an ideal platform for studying high-mobility, low-density electrons in reduced dimensions. The realization of superconductivity in heavily doped diamond, silicon, silicon carbide and germanium suggests that Cooper pairs eventually may be directly incorporated in semiconductor heterostructures, but these newly discovered superconductors are currently limited by their extremely large electronic disorder. Similarly, the electron mean free path in low-dimensional superconducting thin films is usually limited by interface scattering, in single-crystal or polycrystalline samples, or atomic-scale disorder, in amorphous materials, confining these examples to the extreme ‘dirty limit’. Here we report the fabrication of a high-quality superconducting layer within a thin-film heterostructure based on SrTiO3 (the first known superconducting semiconductor). By selectively doping a narrow region of SrTiO3 with the electron-donor niobium, we form a superconductor that is two-dimensional, as probed by the anisotropy of the upper critical magnetic field. Unlike in previous examples, however, the electron mobility is high enough that the normal-state resistance exhibits Shubnikov–de Haas oscillations that scale with the perpendicular field, indicating two-dimensional states. These results suggest that delta-doped SrTiO3 provides a model system in which to explore the quantum transport and interplay of both superconducting and normal electrons. They also demonstrate that high-quality complex oxide heterostructures can maintain electron coherence on the macroscopic scales probed by transport, as well as on the microscopic scales demonstrated previously.
Nature 462, 491 (2009). doi:10.1038/nature08570
Authors: Saroj P. Dash, Sandeep Sharma, Ram S. Patel, Michel P. de Jong & Ron Jansen
The control and manipulation of the electron spin in semiconductors is central to spintronics, which aims to represent digital information using spin orientation rather than electron charge. Such spin-based technologies may have a profound impact on nanoelectronics, data storage, and logic and computer architectures. Recently it has become possible to induce and detect spin polarization in otherwise non-magnetic semiconductors (gallium arsenide and silicon) using all-electrical structures, but so far only at temperatures below 150 K and in n-type materials, which limits further development. Here we demonstrate room-temperature electrical injection of spin polarization into n-type and p-type silicon from a ferromagnetic tunnel contact, spin manipulation using the Hanle effect and the electrical detection of the induced spin accumulation. A spin splitting as large as 2.9 meV is created in n-type silicon, corresponding to an electron spin polarization of 4.6%. The extracted spin lifetime is greater than 140 ps for conduction electrons in heavily doped n-type silicon at 300 K and greater than 270 ps for holes in heavily doped p-type silicon at the same temperature. The spin diffusion length is greater than 230 nm for electrons and 310 nm for holes in the corresponding materials. These results open the way to the implementation of spin functionality in complementary silicon devices and electronic circuits operating at ambient temperature, and to the exploration of their prospects and the fundamental rules that govern their behaviour.
Nature 462, 495 (2009). doi:10.1038/nature08519
Authors: A. Biastoch, C. W. Böning, F. U. Schwarzkopf & J. R. E. Lutjeharms
The transport of warm and salty Indian Ocean waters into the Atlantic Ocean—the Agulhas leakage—has a crucial role in the global oceanic circulation and thus the evolution of future climate. At present these waters provide the main source of heat and salt for the surface branch of the Atlantic meridional overturning circulation (MOC). There is evidence from past glacial-to-interglacial variations in foraminiferal assemblages and model studies that the amount of Agulhas leakage and its corresponding effect on the MOC has been subject to substantial change, potentially linked to latitudinal shifts in the Southern Hemisphere westerlies. A progressive poleward migration of the westerlies has been observed during the past two to three decades and linked to anthropogenic forcing, but because of the sparse observational records it has not been possible to determine whether there has been a concomitant response of Agulhas leakage. Here we present the results of a high-resolution ocean general circulation model to show that the transport of Indian Ocean waters into the South Atlantic via the Agulhas leakage has increased during the past decades in response to the change in wind forcing. The increased leakage has contributed to the observed salinification of South Atlantic thermocline waters. Both model and historic measurements off South America suggest that the additional Indian Ocean waters have begun to invade the North Atlantic, with potential implications for the future evolution of the MOC.
Nature 462, 499 (2009). doi:10.1038/nature08552
Authors: Yun Wang, Donald W. Forsyth & Brian Savage
In the past six million years, Baja California has rifted obliquely apart from North America, opening up the Gulf of California. Between transform faults, seafloor spreading and rifting is well established in several basins. Other than hotspot-dominated Iceland, the Gulf of California is the only part of the world’s seafloor-spreading system that has been surrounded by enough seismometers to provide horizontal resolution of upper-mantle structure at a scale of 100 kilometres over a distance great enough to include several spreading segments. Such resolution is needed to address the long-standing debate about the relative importance of dynamic and passive upwelling in the shallow mantle beneath spreading centres. Here we use Rayleigh-wave tomography to image the shear velocity in the upper 200 kilometres or so of the mantle. Low shear velocities similar to those beneath the East Pacific Rise oceanic spreading centre underlie the entire length of the Gulf, but there are three concentrated locations of anomalously low velocities spaced about 250 kilometres apart. These anomalies are 40 to 90 kilometres beneath the surface, at which depths petrological studies indicate that extensive melting of passively upwelling mantle should begin. We interpret these seismic velocity anomalies as indicating that partial melting triggers dynamic upwelling driven by either the buoyancy of retained melt or by the reduced density of depleted mantle.
Nature 462, 502 (2009). doi:10.1038/nature08572
Authors: Bryan Gick & Donald Derrick
Visual information from a speaker’s face can enhance or interfere with accurate auditory perception. This integration of information across auditory and visual streams has been observed in functional imaging studies, and has typically been attributed to the frequency and robustness with which perceivers jointly encounter event-specific information from these two modalities. Adding the tactile modality has long been considered a crucial next step in understanding multisensory integration. However, previous studies have found an influence of tactile input on speech perception only under limited circumstances, either where perceivers were aware of the task or where they had received training to establish a cross-modal mapping. Here we show that perceivers integrate naturalistic tactile information during auditory speech perception without previous training. Drawing on the observation that some speech sounds produce tiny bursts of aspiration (such as English ‘p’), we applied slight, inaudible air puffs on participants’ skin at one of two locations: the right hand or the neck. Syllables heard simultaneously with cutaneous air puffs were more likely to be heard as aspirated (for example, causing participants to mishear ‘b’ as ‘p’). These results demonstrate that perceivers integrate event-relevant tactile information in auditory perception in much the same way as they do visual information.
Nature 462, 505 (2009). doi:10.1038/nature08596
Authors: Reiko Hanada, Andreas Leibbrandt, Toshikatsu Hanada, Shiho Kitaoka, Tomoyuki Furuyashiki, Hiroaki Fujihara, Jean Trichereau, Magdalena Paolino, Fatimunnisa Qadri, Ralph Plehm, Steffen Klaere, Vukoslav Komnenovic, Hiromitsu Mimata, Hironobu Yoshimatsu, Naoyuki Takahashi, Arndt von Haeseler, Michael Bader, Sara Sebnem Kilic, Yoichi Ueta, Christian Pifl, Shuh Narumiya & Josef M. Penninger
Receptor-activator of NF-κB ligand (TNFSF11, also known as RANKL, OPGL, TRANCE and ODF) and its tumour necrosis factor (TNF)-family receptor RANK are essential regulators of bone remodelling, lymph node organogenesis and formation of a lactating mammary gland. RANKL and RANK are also expressed in the central nervous system. However, the functional relevance of RANKL/RANK in the brain was entirely unknown. Here we report that RANKL and RANK have an essential role in the brain. In both mice and rats, central RANKL injections trigger severe fever. Using tissue-specific Nestin-Cre and GFAP-Cre rankfloxed deleter mice, the function of RANK in the fever response was genetically mapped to astrocytes. Importantly, Nestin-Cre and GFAP-Cre rankfloxed deleter mice are resistant to lipopolysaccharide-induced fever as well as fever in response to the key inflammatory cytokines IL-1β and TNFα. Mechanistically, RANKL activates brain regions involved in thermoregulation and induces fever via the COX2-PGE2/EP3R pathway. Moreover, female Nestin-Cre and GFAP-Cre rankfloxed mice exhibit increased basal body temperatures, suggesting that RANKL and RANK control thermoregulation during normal female physiology. We also show that two children with RANK mutations exhibit impaired fever during pneumonia. These data identify an entirely novel and unexpected function for the key osteoclast differentiation factors RANKL/RANK in female thermoregulation and the central fever response in inflammation.
Nature 462, 510 (2009). doi:10.1038/nature08511
Authors: Yusuke Nakanishi, Bao Lu, Craig Gerard & Akiko Iwasaki
CD4+ T helper cells are well known for their role in providing critical signals during priming of cytotoxic CD8+ T lymphocyte (CTL) responses in vivo. T-cell help is required for the generation of primary CTL responses as well as in promoting protective CD8+ memory T-cell development. However, the role of CD4 help in the control of CTL responses at the effector stage is unknown. Here we show that fully helped effector CTLs are themselves not self-sufficient for entry into the infected tissue, but rely on the CD4+ T cells to provide the necessary cue. CD4+ T helper cells control the migration of CTL indirectly through the secretion of IFN-γ and induction of local chemokine secretion in the infected tissue. Our results reveal a previously unappreciated role of CD4 help in mobilizing effector CTL to the peripheral sites of infection where they help to eliminate infected cells.
Nature 462, 514 (2009). doi:10.1038/nature08594
Authors: Tsuneo Hakoyama, Kaori Niimi, Hirokazu Watanabe, Ryohei Tabata, Junichi Matsubara, Shusei Sato, Yasukazu Nakamura, Satoshi Tabata, Li Jichun, Tsuyoshi Matsumoto, Kazuyuki Tatsumi, Mika Nomura, Shigeyuki Tajima, Masumi Ishizaka, Koji Yano, Haruko Imaizumi-Anraku, Masayoshi Kawaguchi, Hiroshi Kouchi & Norio Suganuma
Homocitrate is a component of the iron–molybdenum cofactor in nitrogenase, where nitrogen fixation occurs. NifV, which encodes homocitrate synthase (HCS), has been identified from various diazotrophs but is not present in most rhizobial species that perform efficient nitrogen fixation only in symbiotic association with legumes. Here we show that the FEN1 gene of a model legume, Lotus japonicus, overcomes the lack of NifV in rhizobia for symbiotic nitrogen fixation. A Fix- (non-fixing) plant mutant, fen1, forms morphologically normal but ineffective nodules. The causal gene, FEN1, was shown to encode HCS by its ability to complement a HCS-defective mutant of Saccharomyces cerevisiae. Homocitrate was present abundantly in wild-type nodules but was absent from ineffective fen1 nodules. Inoculation with Mesorhizobium loti carrying FEN1 or Azotobacter vinelandii NifV rescued the defect in nitrogen-fixing activity of the fen1 nodules. Exogenous supply of homocitrate also recovered the nitrogen-fixing activity of the fen1 nodules through de novo nitrogenase synthesis in the rhizobial bacteroids. These results indicate that homocitrate derived from the host plant cells is essential for the efficient and continuing synthesis of the nitrogenase system in endosymbionts, and thus provide a molecular basis for the complementary and indispensable partnership between legumes and rhizobia in symbiotic nitrogen fixation.
Nature 462, 518 (2009). doi:10.1038/nature08587
Authors: Graham Peers, Thuy B. Truong, Elisabeth Ostendorf, Andreas Busch, Dafna Elrad, Arthur R. Grossman, Michael Hippler & Krishna K. Niyogi
Light is necessary for photosynthesis, but its absorption by pigment molecules such as chlorophyll can cause severe oxidative damage and result in cell death. The excess absorption of light energy by photosynthetic pigments has led to the evolution of protective mechanisms that operate on the timescale of seconds to minutes and involve feedback-regulated de-excitation of chlorophyll molecules in photosystem II (qE). Despite the significant contribution of eukaryotic algae to global primary production, little is known about their qE mechanism, in contrast to that in flowering plants. Here we show that a qE-deficient mutant of the unicellular green alga Chlamydomonas reinhardtii, npq4, lacks two of the three genes encoding LHCSR (formerly called LI818). This protein is an ancient member of the light-harvesting complex superfamily, and orthologues are found throughout photosynthetic eukaryote taxa, except in red algae and vascular plants. The qE capacity of Chlamydomonas is dependent on environmental conditions and is inducible by growth under high light conditions. We show that the fitness of the npq4 mutant in a shifting light environment is reduced compared to wild-type cells, demonstrating that LHCSR is required for survival in a dynamic light environment. Thus, these data indicate that plants and algae use different proteins to dissipate harmful excess light energy and protect the photosynthetic apparatus from damage.
Nature 462, 522 (2009). doi:10.1038/nature08576
Authors: Nir Netzer, Jeffrey M. Goodenbour, Alexandre David, Kimberly A. Dittmar, Richard B. Jones, Jeffrey R. Schneider, David Boone, Eva M. Eves, Marsha R. Rosner, James S. Gibbs, Alan Embry, Brian Dolan, Suman Das, Heather D. Hickman, Peter Berglund, Jack R. Bennink, Jonathan W. Yewdell & Tao Pan
Translational fidelity, essential for protein and cell function, requires accurate transfer RNA (tRNA) aminoacylation. Purified aminoacyl-tRNA synthetases exhibit a fidelity of one error per 10,000 to 100,000 couplings. The accuracy of tRNA aminoacylation in vivo is uncertain, however, and might be considerably lower. Here we show that in mammalian cells, approximately 1% of methionine (Met) residues used in protein synthesis are aminoacylated to non-methionyl-tRNAs. Remarkably, Met-misacylation increases up to tenfold upon exposing cells to live or non-infectious viruses, toll-like receptor ligands or chemically induced oxidative stress. Met is misacylated to specific non-methionyl-tRNA families, and these Met-misacylated tRNAs are used in translation. Met-misacylation is blocked by an inhibitor of cellular oxidases, implicating reactive oxygen species (ROS) as the misacylation trigger. Among six amino acids tested, tRNA misacylation occurs exclusively with Met. As Met residues are known to protect proteins against ROS-mediated damage, we propose that Met-misacylation functions adaptively to increase Met incorporation into proteins to protect cells against oxidative stress. In demonstrating an unexpected conditional aspect of decoding mRNA, our findings illustrate the importance of considering alternative iterations of the genetic code.
Nature 462, 534 (2009). doi:10.1038/462534a
Author: Shelly Li
Being human.