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Current Biology
This journal offers authors two options (open access or subscription) to publish research

May 24, 2005

Volume 15Issue 10p886-981, R359-R394
Open Archive

Magazine

  • European Union seeks support for top research council

    • Michael Gross
    Winning research funds from the European Union has often been viewed as complex, opaque and largely geared to more applied work, but plans for a new European Research Council may help change that. Michael Gross reports.
  • Battle for continent standards

    • Nigel Williams
    Nigel Williams reports on an effort to develop common standards within Europe’s diverse higher education systems to promote greater mobility.
  • James W. Valentine

    • James W. Valentine
    Jim Valentine went to college on the GI Bill (a WWII veterans privilege) and has been there ever since; at present he is Professor of Integrative Biology, Emeritus, at UC Berkeley. His early research was on what is now called macroecology, working with fossil marine faunas, leading to a book, Evolutionary Paleoecology of the Marine Biosphere. Those studies continue today, chiefly with colleagues Dave Jablonski and Kaustuv Roy. More recently he became fascinated with the power of findings in molecular developmental biology to explain, or at least to provide a general understanding of, the sorts of morphological patterns found in the fossil record; his latest book, On the Origin of Phyla, examines the events surrounding the Cambrian explosion and their implications for interpreting developmental evolution.
  • Stem cell tensions mount

    • Nigel Williams
    The US has been a major battleground amongst legislators coming to grips with the issue of embryonic stem cell research but the issue is reaching new heights in Italy. Nigel Williams reports.
  • Spiders’ webs

    • Fritz Vollrath
    What is a spider’s web? Webs provide spiders with a means to trap their food and, in some cases, a place to shelter. Webs consist of blends of different silks, cleverly combined for functionality. Take the ‘typical’ orb web of the common garden spider (compare the photo on this page), which has evolved to take out-of-plane loads at optimized deflections. To be able to do so, this web needs to incorporate into one structure the mechanical properties of very different types of silk: the fairly stiff, radius silk threads and the extremely soft, extensible and sticky capture silk threads, which are fixed on the radii by stringy silk cement.
  • In between the sheets

    • Nigel Williams
    A new book of pictures by Robyn Stacey, one of Australia’s finest photographers, published by Cambridge University Press, is a first of its kind. Stacey, along with writer Ashley Hay, throws open the doors of the National Herbarium of New South Wales at the Royal Botanic Gardens, Sydney, to reveal the secret history of Australia’s flora. Herbarium tells the stories about the nature of collecting, those who collected, what they collected and when, and also provides the scientific background to each of the specimens photographed by Stacey.
  • Phylogeography

    • Brent C. Emerson,
    • Godfrey M. Hewitt
    Phylogeography [1] is a young and fast-growing field that analyses the geographical distribution of genealogical lineages. It grew out of the new techniques of the 1980s that made it possible to determine DNA sequence variation from individuals across a species range, and hence to reconstruct gene genealogies. The spatial relationships of such genealogies may be displayed geographically and analysed to deduce the evolutionary history of populations, subspecies and species. In particular, the technical accessibility of mitochondrial (mt)DNA sequences in animal species kindled and fuelled this new field.
  • A left-sided visuospatial bias in birds

    • Bettina Diekamp,
    • Lucia Regolin,
    • Onur Güntürkün,
    • Giorgio Vallortigara
    Humans primarily attend to objects in the left side of space, as shown in cancellation tasks routinely used during neuropsychological testing [1,2]. This asymmetry is thought to arise from a right hemispheric superiority in the control of spatial attentional resources [3], and is assumed to depend on the corpus callosum which mediates fast communication between two specialized hemispheres of the brain [4]. We tested two species of birds in a task that closely matches the cancellation task: the birds were required to explore an area in front of them and to sample grains.
  • Nematode Memory: Now, Where Was I?

    • Catharine H. Rankin
    The nematode Caenorhabditis elegans is able to use tastes, smells and temperature to locate food. New data show that worms can also detect the level of oxygen in the environment and migrate towards an oxygen level associated with food.
  • BMP Signalling: Synergy and Feedback Create a Step Gradient

    • Hilary L. Ashe
    A central theme in the development of multicellular organisms is that fields of cells are patterned by gradients of signalling molecules in a concentration dependent manner. For example, gradients of bone morphogenetic proteins (BMPs), which are members of the TGF-β superfamily, pattern the dorsal–ventral axes in vertebrate and invertebrate embryos [1]. In the Drosophila embryo, this process requires two BMP signalling molecules, Decapentaplegic (Dpp) and Screw (Scw) [2]. Two groups have recently visualised the distribution of Dpp in wild-type and mutant embryos [3,4].
  • DNA Dynamics: Bubble ‘n’ Flip for DNA Cyclisation?

    • Andrew Travers
    A recent demonstration of the facile in vitro formation of DNA microcircles of fewer than 100 base pairs throws new light on the basis of DNA flexibility.
  • Chromosome Segregation: Aurora B Gets Tousled

    • Christopher T. Richie,
    • Andy Golden
    Aurora B kinases play important roles during mitosis in eukaryotic cells; new work in Caenorhabditis elegans has identified the Tousled kinase TLK-1 as a substrate activator of the model nematode’s AuroraB kinase AIR-2 which acts to ensure proper chromosome segregation during cell division.
  • Immunology: How Do T Cells Recognize Antigen?

    • Kaushik Choudhuri,
    • Alice Kearney,
    • Talitha R. Bakker,
    • P. Anton van der Merwe
    KT cells recognize small fragments of microorganisms (antigens) on the surface of other cells using T cell antigen receptors. The mechanism by which these receptors signal into T cells is controversial, but two recent studies provide important new clues.
  • ATP Synthesis: The World’s Smallest Wind-Up Toy

    • Richard M Berry
    ATP synthase contains two rotary motors coupled back-to-back: the protonmotive force-driven motor F0 pushes the ATP-driven motor F1 in reverse, causing it to synthesize ATP. Half of this process has now been reproduced in vitro, using tiny magnets instead of F0 to drive the reverse rotation of a single F1 molecule.
  • MicroRNAs: All Gone and Then What?

    • Oliver Hobert
    MicroRNAs are abundant gene regulatory factors whose function in animal development and homeostasis is poorly understood. A new study reports the genetic elimination of miRNA function on a full genomic scale and identifies a subfamily of miRNAs involved in brain morphogenesis.
  • Time Perception: Components of the Brain’s Clock

    • Penelope A. Lewis,
    • Vincent Walsh
    We know the human brain contains some kind of clock, but determining its neural underpinnings and teasing apart its components have proven difficult. New work on the parietal cortex illustrates how single unit recording may be able to help.
  • Axis Formation: Redundancy Rules

    • Christof Niehrs
    The role of BMP antagonists in the Spemann-Mangold organizer of vertebrate embryos is a controversial issue. A study using combined knock down of multiple antagonists finally reveals dramatic effects.

Articles

  • A GABAergic Mechanism Is Necessary for Coupling Dissociable Ventral and Dorsal Regional Oscillators within the Circadian Clock

    • Henk Albus,
    • Mariska J. Vansteensel,
    • Stephan Michel,
    • Gene D. Block,
    • Johanna H. Meijer
    Background: Circadian rhythms in mammalian behavior, physiology, and biochemistry are controlled by the central clock of the suprachiasmatic nucleus (SCN). The clock is synchronized to environmental light-dark cycles via the retino-hypothalamic tract, which terminates predominantly in the ventral SCN of the rat. In order to understand synchronization of the clock to the external light-dark cycle, we performed ex vivo recordings of spontaneous impulse activity in SCN slices of the rat.Results: We observed bimodal patterns of spontaneous impulse activity in the dorsal and ventral SCN after a 6 hr delay of the light schedule.
  • The C. elegans Tousled-like Kinase Contributes to Chromosome Segregation as a Substrate and Regulator of the Aurora B Kinase

    • Zhenbo Han,
    • Gary M. Riefler,
    • Jennifer R. Saam,
    • Susan E. Mango,
    • Jill M. Schumacher
    Background: The Aurora kinases control multiple aspects of mitosis, among them centrosome maturation, spindle assembly, chromosome segregation, and cytokinesis. Aurora activity is regulated in part by a subset of Aurora substrates that, once phosphorylated, can enhance Aurora kinase activity. Aurora A substrate activators include TPX2 and Ajuba, whereas the only known Aurora B substrate activator is the chromosomal passenger INCENP.Results: We report that the C. elegans Tousled kinase TLK-1 is a second substrate activator of the Aurora B kinase AIR-2.
  • Experience-Dependent Modulation of C. elegans Behavior by Ambient Oxygen

    • Benny H.H. Cheung,
    • Merav Cohen,
    • Candida Rogers,
    • Onder Albayram,
    • Mario de Bono
    Background: Ambient oxygen (O2) influences the behavior of organisms from bacteria to man. In C. elegans, an atypical O2 binding soluble guanylate cyclase (sGC), GCY-35, regulates O2 responses. However, how acute and chronic changes in O2 modify behavior is poorly understood.Results: Aggregating C. elegans strains can respond to a reduction in ambient O2 by a rapid, reversible, and graded inhibition of roaming behavior. This aerokinetic response is mediated by GCY-35 and GCY-36 sGCs, which appear to become activated as O2 levels drop and to depolarize the AQR, PQR, and URX neurons.
  • Presynaptic Spectrin Is Essential for Synapse Stabilization

    • Jan Pielage,
    • Richard D. Fetter,
    • Graeme W. Davis
    Background: Precise neural circuitry is established and maintained through a regulated balance of synapse stabilization and disassembly. Currently, little is known about the molecular mechanisms that specify synapse stability versus disassembly.Results: Here, we demonstrate that presynaptic spectrin is an essential scaffold that is required to maintain synapse stability at the Drosophila neuromuscular junction (NMJ). Loss of presynaptic spectrin leads to synapse disassembly and ultimately to the elimination of the NMJ.

Reports

  • The Pungency of Garlic: Activation of TRPA1 and TRPV1 in Response to Allicin

    • Lindsey J. Macpherson,
    • Bernhard H. Geierstanger,
    • Veena Viswanath,
    • Michael Bandell,
    • Samer R. Eid,
    • SunWook Hwang,
    • Ardem Patapoutian
    Garlic’s pungent flavor has made it a popular ingredient in cuisines around the world and throughout history. Garlic’s health benefits have been elevated from folklore to clinical study [1–5]. Although there is some controversy as to the efficacy of garlic, garlic products are one of the most popular herbal supplements in the U.S. [6]. Chemically complex, garlic contains different assortments of sulfur compounds depending on whether the cloves are intact, crushed, cooked, or raw [7]. Raw garlic, when cut and placed on the tongue or lips, elicits painful burning and prickling sensations through unknown mechanisms.
  • Functional Genomics of the Cilium, a Sensory Organelle

    • Oliver E. Blacque,
    • Elliot A. Perens,
    • Keith A. Boroevich,
    • Peter N. Inglis,
    • Chunmei Li,
    • Adam Warner,
    • Jaswinder Khattra,
    • Rob A. Holt,
    • Guangshuo Ou,
    • Allan K. Mah,
    • Sheldon J. McKay,
    • Peter Huang,
    • Peter Swoboda,
    • Steve J.M. Jones,
    • Marco A. Marra,
    • David L. Baillie,
    • Donald G. Moerman,
    • Shai Shaham,
    • Michel R. Leroux
    Cilia and flagella play important roles in many physiological processes, including cell and fluid movement, sensory perception, and development [1]. The biogenesis and maintenance of cilia depend on intraflagellar transport (IFT), a motility process that operates bidirectionally along the ciliary axoneme [1, 2]. Disruption in IFT and cilia function causes several human disorders, including polycystic kidneys, retinal dystrophy, neurosensory impairment, and Bardet-Biedl syndrome (BBS) [3–5]. To uncover new ciliary components, including IFT proteins, we compared C.
  • The Murine Polycomb Group Protein Eed Is Required for Global Histone H3 Lysine-27 Methylation

    • Nathan D. Montgomery,
    • Della Yee,
    • Andrew Chen,
    • Sundeep Kalantry,
    • Stormy J. Chamberlain,
    • Arie P. Otte,
    • Terry Magnuson
    PcG proteins mediate heritable transcriptional silencing by generating and recognizing covalent histone modifications. One conserved PcG complex, PRC2, is composed of several proteins including the histone methyltransferase (HMTase) Ezh2, the WD-repeat protein Eed, and the Zn-finger protein Suz12. Ezh2 methylates histone H3 on lysine 27 (H3K27) [1–4], which serves as an epigenetic mark mediating silencing. H3K27 can be mono-, di-, or trimethylated (1mH3K27, 2mH3K27, and 3mH3K27, respectively) [5].
  • A REC8-Dependent Plant Shugoshin Is Required for Maintenance of Centromeric Cohesion during Meiosis and Has No Mitotic Functions

    • Olivier Hamant,
    • Inna Golubovskaya,
    • Robert Meeley,
    • Elisa Fiume,
    • Ljuda Timofejeva,
    • Alexander Schleiffer,
    • Kim Nasmyth,
    • W. Zacheus Cande
    During meiosis, sequential release of sister chromatid cohesion (SSC) during two successive nuclear divisions allows the production of haploid gametes from diploid progenitor cells. Release of SSC along chromosome arms allows first a reductional segregation of homologs, and, subsequently, release of centromeric cohesion at anaphase II allows the segregation of chromatids [1–3]. The Shugoshin (SGO) protein family plays a major role in the protection of centromeric cohesion in Drosophila and yeast [4–12].
  • Lethal Giant Larvae Controls the Localization of Notch-Signaling Regulators Numb, Neuralized, and Sanpodo in Drosophila Sensory-Organ Precursor Cells

    • Johanna Langevin,
    • Roland Le Borgne,
    • François Rosenfeld,
    • Michel Gho,
    • François Schweisguth,
    • Yohanns Bellaïche
    Asymmetric distribution of fate determinants is a fundamental mechanism underlying the acquisition of distinct cell fates during asymmetric division. In Drosophila neuroblasts, the apical DmPar6/DaPKC complex inhibits Lethal giant larvae (Lgl) to promote the basal localization of fate determinants [1–3]. In contrast, in the sensory precursor (pI) cells that divide asymmetrically with a planar polarity, Lgl inhibits Notch signaling in the anterior pI daughter cell, pIIb, by a yet-unknown mechanism [4].
  • mRNA Surveillance of Expressed Pseudogenes in C. elegans

    • Quinn M. Mitrovich,
    • Philip Anderson
    Messenger RNAs (mRNAs) that contain premature translation termination codons (PTCs) are targeted for rapid degradation in all eukaryotes tested. The mechanisms of nonsense-mediated mRNA decay (NMD) have been described in considerable detail [1, 2], but the biological roles of NMD in wild-type organisms are poorly understood. mRNAs of wild-type organisms known to be degraded by NMD (“natural targets” of NMD) include by-products of regulated alternative splicing [3–6], out-of-frame mRNAs derived from unproductive gene rearrangements [7, 8], cytoplasmic pre-mRNAs [9, 10], endogenous retroviral and transposon RNAs [11], and mRNAs having upstream open reading frames or other unusual sequence features [11–14].
  • NRG1, a CC-NB-LRR Protein, together with N, a TIR-NB-LRR Protein, Mediates Resistance against Tobacco Mosaic Virus

    • Jack R. Peart,
    • Pere Mestre,
    • Rui Lu,
    • Isabelle Malcuit,
    • David C. Baulcombe
    In animals and plants, innate immunity is regulated by nucleotide binding domain and leucine-rich repeat (NB-LRR) proteins that mediate pathogen recognition and that activate host-cell defense responses [1, 2]. Plant NB-LRR proteins, referred to as R proteins, have amino-terminal domains that contain a coiled coil (CC) or that share similarity with animal Toll and interleukin 1 receptors (TIR) [3]. To investigate R protein function, we are using the TIR-NB-LRR protein N that mediates resistance against tobacco mosaic virus (TMV) [4] through recognition of the TMV p50 protein.
  • Small Nuclear RNAs Encoded by Herpesvirus saimiri Upregulate the Expression of Genes Linked to T Cell Activation in Virally Transformed T Cells

    • Heidi L. Cook,
    • J. Robin Lytle,
    • Hannah E. Mischo,
    • Ming-Jie Li,
    • John J. Rossi,
    • Daniel P. Silva,
    • Ronald C. Desrosiers,
    • Joan A. Steitz
    Seven small nuclear RNAs of the Sm class are encoded by Herpesvirus saimiri (HVS), a γ Herpesvirus that causes aggressive T cell leukemias and lymphomas in New World primates and efficiently transforms T cells in vitro [1–4]. The Herpesvirus saimiri U RNAs (HSURs) are the most abundant viral transcripts in HVS-transformed, latently infected T cells but are not required for viral replication or transformation in vitro [5]. We have compared marmoset T cells transformed with wild-type or a mutant HVS lacking the most highly conserved HSURs, HSURs 1 and 2.

Errata

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