Latest Articles Include:
- Battle lines deepen to save bluefin tuna
- Curr Biol 19(15):R625-R626 (2009)
A ban on the international trade in this lucrative fish is now being considered as current conservation measures have still seen stocks collapse. Nigel Williams reports. - New grids on the block
- Curr Biol 19(15):R626-R627 (2009)
Meeting both carbon emission targets and energy demands may be feasible with DC cables connecting power-thirsty cities to sun-drenched deserts. Michael Gross reports. - Flagging up a neglected killer
- Curr Biol 19(15):R628-R629 (2009)
This year marks the centenary of the discovery by the Brazilian doctor Carlos Chagas of the parasite and insect vectors which cause the disease that carries his name. A new campaign aims to boost work on this major infection in Latin America. Nigel Williams reports. - Collective rationality
- Curr Biol 19(15):R629-R630 (2009)
A new study suggests ant colonies can avoid irrational changes in preference that can be shown by individual animals and humans. Nigel Williams reports. - Masters of the monsoon
- Curr Biol 19(15):R631 (2009)
- Steve Simpson
- Curr Biol 19(15):R632-R633 (2009)
- Fission–fusion populations
Couzin ID Laidre ME - Curr Biol 19(15):R633-R635 (2009)
- Evolution of sound localisation in land vertebrates
Köppl C - Curr Biol 19(15):R635-R639 (2009)
- CNS Evolution: New Insight from the Mud
Benito-Gutiérrez E Arendt D - Curr Biol 19(15):R640-R642 (2009)
Whether the highly centralised nervous systems of chordates and protostomes arose from a common ancestral precursor or independently has been a long-standing debate. Now, analysis of neural gene expression in an evolutionarily important chordate outgroup — the sand-dwelling, hemichordate acorn worms — reveals the presence of a central and peripheral nervous system, suggesting a common origin of central nervous systems. - Cancer: CINful Centrosomes
Bakhoum SF Compton DA - Curr Biol 19(15):R642-R645 (2009)
The regulation of centrosome number is lost in many tumors and the presence of extra centrosomes correlates with chromosomal instability. Recent work now reveals how extra centrosomes cause chromosome mis-segregation in tumor cells. - Recognition Memory: What's New in Novelty Signals?
Brown MW - Curr Biol 19(15):R645-R647 (2009)
A new study indicates that signals distinguishing between new and old stimuli are present very rapidly in the human brain, but only when subjects are motivated by explicit reward instructions. - Reproductive Biology: Receptor-Like Kinases Orchestrate Love Songs in Plants
Berger F - Curr Biol 19(15):R647-R649 (2009)
Genetic studies have identified a family of receptor-like kinases (RLKs) involved in the control of reproduction in the model plant Arabidopsis. Each RLK-dependent signaling pathway is active in cells associated with either male or female gametes. Collectively, these RLKs control the delivery of sperm cells to female gametes. - Small RNAs: How Seeds Remember To Obey Their Mother
Springer NM - Curr Biol 19(15):R649-R651 (2009)
The endosperm is one of two products from the double fertilization event that occurs during sexual reproduction in flowering plants. A series of recent reports highlights the unusual genetic regulatory mechanisms that occur in endosperm and suggests a role for transposon regulation in imprinting. - Gaze Perception: Is Seeing Influenced by Believing?
Langton SR - Curr Biol 19(15):R651-R653 (2009)
Gaze perception has been thought to be stimulus-driven. This view is challenged by a new demonstration that a gaze direction aftereffect can be influenced by beliefs about the gazer's ability to see. - Chemical Signalling: Laser on the Fly Reveals a New Male-Specific Pheromone
Levine JD Millar JG - Curr Biol 19(15):R653-R655 (2009)
A study using laser desorption/ionization mass spectrometry has identified new oxygenated compounds in cuticular lipids of the fruit fly Drosophila melanogaster; one such compound, when transferred to females during mating, renders the females unattractive to males for days. - Taste Perception: How Sweet It Is (To Be Transcribed by You)
Mainland JD Matsunami H - Curr Biol 19(15):R655-R656 (2009)
In mammals, sweet taste is mediated largely by a single receptor. New work shows that polymorphisms in the promoter region of one subunit contribute to variation in sweet perception in the human population. - Converging Pathways in Lifespan Regulation
Narasimhan SD Yen K Tissenbaum HA - Curr Biol 19(15):R657-R666 (2009)
The processes that determine an organism's lifespan are complex and poorly understood. Yet single gene manipulations and environmental interventions can substantially delay age-related morbidity. In this review, we focus on the two most potent modulators of longevity: insulin/insulin-like growth factor 1 (IGF-1) signaling and dietary restriction. The remarkable molecular conservation of the components associated with insulin/IGF-1 signaling and dietary restriction allow us to understand longevity from a multi-species perspective. We summarize the most recent findings on insulin/IGF-1 signaling and examine the proteins and pathways that reveal a more genetic basis for dietary restriction. Although insulin/IGF-1 signaling and dietary restriction pathways are currently viewed as being independent, we suggest that these two pathways are more intricately connected than previously appreciated. We highlight that numerous interactions between these two pathways can occur at mu! ltiple levels. Ultimately, both the insulin/IGF-1 pathway and the pathway that mediates the effects of dietary restriction have evolved to respond to the nutritional status of an organism, which in turn affects its lifespan. - A New Male Sex Pheromone and Novel Cuticular Cues for Chemical Communication in Drosophila
Yew JY Dreisewerd K Luftmann H Müthing J Pohlentz G Kravitz EA - Curr Biol 19(15):1245-1254 (2009)
Background In many insect species, cuticular hydrocarbons serve as pheromones that can mediate complex social behaviors. In Drosophila melanogaster, several hydrocarbons including the male sex pheromone 11-cis-vaccenyl acetate (cVA) and female-specific 7,11-dienes influence courtship behavior and can function as cues for short-term memory associated with the mating experience. Behavioral and physiological studies suggest that other unidentified chemical communication cues are likely to exist. To more fully characterize the hydrocarbon profile of the D. melanogaster cuticle, we applied direct ultraviolet laser desorption/ionization orthogonal time-of-flight mass spectrometry (UV-LDI-o-TOF MS) and analyzed the surface of intact fruit flies at a spatial resolution of approximately 200 μm. Results We report the chemical and spatial characterization of 28 species of cuticular hydrocarbons, including a new major class of oxygen-containing compounds. Via UV-LDI MS, pheromones previously shown to be expressed exclusively by one sex, e.g., cVA, 7,11-heptacosadiene, and 7,11-nonacosadiene, appear to be found on both male and female flies. In males, cVA colocalizes at the tip of the ejaculatory bulb with a second acetylated hydrocarbon named CH503. We describe the chemical structure of CH503 as 3-O-acetyl-1,3-dihydroxy-octacosa-11,19-diene and demonstrate a behavioral role for this compound as a long-lived inhibitor of male courtship. Like cVA, CH503 is transferred from males to females during mating. Unlike cVA, CH503 remains on the surface of females for at least 10 days. Conclusions Oxygenated hydrocarbons comprise a major previously undescribed class of compounds on the Drosophila cuticular surface. A newly discovered long-chain acetate, CH503, serves as a mediator of courtship-related chemical communication. - ITCH K63-Ubiquitinates the NOD2 Binding Protein, RIP2, to Influence Inflammatory Signaling Pathways
Tao M Scacheri PC Marinis JM Harhaj EW Matesic LE Abbott DW - Curr Biol 19(15):1255-1263 (2009)
Background The inability to coordinate the signaling pathways that lead to proper cytokine responses characterizes the pathogenesis of inflammatory diseases such as Crohn's disease. The Crohn's disease susceptibility protein, NOD2, helps coordinate cytokine responses upon intracellular exposure to bacteria, and this signal coordination by NOD2 is accomplished, in part, through K63-linked polyubiquitin chains that create binding surfaces for the scaffolding of signaling complexes. Results In this work, we show that the NOD2 signaling partner, RIP2, is directly K63-polyubiquitinated by ITCH, an E3 ubiquitin ligase that when lost genetically causes widespread inflammatory disease at mucosal surfaces. We show that ITCH is responsible for RIP2 polyubiquitination in response to infection with listeria monocytogenes. We also show that NOD2 can bind polyubiquitinated RIP2 and that whereas ITCH E3 ligase activity is required for optimal NOD2:RIP2-induced p38 and JNK activation, ITCH inhibits NOD2:RIP2-induced nuclear factor kappa B (NFκB) activation. This effect can be seen independently at the whole-genome level by microarray analysis of muramyl dipeptide (MDP)-treated Itch−/− primary macrophages. Conclusions These findings suggest that ITCH helps regulate NOD2-dependent signal transduction pathways and, as such, may be involved in the pathogenesis of NOD2-mediated inflammatory disease. - Centralization of the Deuterostome Nervous System Predates Chordates
Nomaksteinsky M Röttinger E Dufour HD Chettouh Z Lowe CJ Martindale MQ Brunet JF - Curr Biol 19(15):1264-1269 (2009)
The origin of the chordate central nervous system (CNS) is unknown. One theory is that a CNS was present in the first bilaterian and that it gave rise to both the ventral cord of protostomes and the dorsal cord of deuterostomes (reviewed in [1]). Another theory (reviewed in [2]) proposes that the chordate CNS arose by a dramatic process of dorsalization and internalization from a diffuse nerve net coextensive with the skin of the animal, such as enteropneust worms (Hemichordata, Ambulacraria) are supposed to have [3]. We show here that juvenile and adult enteropneust worms in fact have a bona fide CNS, i.e., dense agglomerations of neurons associated with a neuropil, forming two cords, ventral and dorsal. The latter is internalized in the collar as a chordate-like neural tube. Contrary to previous assumptions, the greater part of the adult enteropneust skin is nonneural, although elements of the peripheral nervous system (PNS) are found there. We use molecular markers ! to show that several neuronal types are anatomically segregated in the CNS and PNS. These neuroanatomical features, whatever their homologies with the chordate CNS, imply that nervous system centralization predates the evolutionary separation of chordate and hemichordate lineages. - Thatcher Effect in Monkeys Demonstrates Conservation of Face Perception across Primates
Adachi I Chou DP Hampton RR - Curr Biol 19(15):1270-1273 (2009)
Accurate recognition of individuals is a foundation of social cognition. The remarkable ability of humans to distinguish among thousands of similar faces depends on sensitivity to unique configurations of facial features, including subtle differences in the relative placement of the eyes and mouth [1] and [2]. Determining whether similar perceptual processes underlie individual recognition in nonhuman primates is important for both the study of cognitive evolution and the appropriate use of primate models in social cognition research. In humans, some of the best evidence for a keen sensitivity to the configuration of features in faces comes from the "Thatcher effect." This effect shows that it is difficult to detect changes in the orientation of the eyes and mouth in an image of an inverted face, even though identical changes are unmistakable in an upright face [3] and [4]. Here, we demonstrate for the first time that a nonhuman primate species also exhibits the Th! atcher effect. This direct evidence of configural face perception in monkeys, collected under testing conditions that closely parallel those used with humans, indicates that perceptual mechanisms for individual recognition have been conserved through primate cognitive evolution. - Social Cognition Modulates the Sensory Coding of Observed Gaze Direction
Teufel C Alexis DM Todd H Lawrance-Owen AJ Clayton NS Davis G - Curr Biol 19(15):1274-1277 (2009)
Gaze direction is an important social signal in both human and nonhuman primates, providing information about conspecifics' attention, interests, and intentions [1], [2], [3] and [4]. Single-unit recordings in macaques have revealed neurons selective for others' specific gaze direction [5] and [6]. A parallel functional organization in the human brain is indicated by gaze-adaptation experiments, in which systematic distortions in gaze perception following prolonged exposure to static face images reveal dynamic interactions in local cortical circuitry [7] and [8]. However, our understanding of the influence of high-level social cognition on these processes in monkeys and humans is still rudimentary. Here we show that the attribution of a mental state to another person determines the way in which the human brain codes observed gaze direction. Specifically, we convinced observers that prerecorded video sequences of an experimenter gazing left or right were a live video li! nk to an adjacent room. The experimenter wore mirrored goggles that observers believed were either transparent such that the person could see, or opaque such that the person could not see. The effects of adaptation were enhanced under the former condition relative to the latter, indicating that high-level sociocognitive processes shape and modulate sensory coding of observed gaze direction. - Location-Specific Cortical Activation Changes during Sleep after Training for Perceptual Learning
Yotsumoto Y Sasaki Y Chan P Vasios CE Bonmassar G Ito N Náñez JE Shimojo S Watanabe T - Curr Biol 19(15):1278-1282 (2009)
Visual perceptual learning is defined as performance enhancement on a sensory task and is distinguished from other types of learning and memory in that it is highly specific for location of the trained stimulus. The location specificity has been shown to be paralleled by enhancement in functional magnetic resonance imaging (fMRI) signal in the trained region of V1 [1], [2] and [3] after visual training. Although recently the role of sleep in strengthening visual perceptual learning has attracted much attention, its underlying neural mechanism has yet to be clarified. Here, for the first time, fMRI measurement of human V1 activation was conducted concurrently with a polysomnogram during sleep with and without preceding training for visual perceptual learning. As a result of predetermined region-of-interest analysis of V1, activation enhancement during non-rapid-eye-movement sleep after training was observed specifically in the trained region of V1. Furthermore, improvem! ent of task performance measured subsequently to the post-training sleep session was significantly correlated with the amount of the trained-region-specific fMRI activation in V1 during sleep. These results suggest that as far as V1 is concerned, only the trained region is involved in improving task performance after sleep. - Blue and Yellow Signal Cleaning Behavior in Coral Reef Fishes
Cheney KL Grutter AS Blomberg SP Marshall NJ - Curr Biol 19(15):1283-1287 (2009)
Marine cleaning symbioses are classic examples of mutualism: cleaners remove and consume ectoparasites from "client" fish, while clients benefit from a reduction in ectoparasites [1] and [2]. However, how clients recognize cleaners and decide not to eat them is unclear. Color and body pattern are thought to be important in signaling cleaning services to coral reef fish [1], [3] and [4]; in this study, we tested the long-held belief that cleaner fish display a blue "guild" coloration [5], [6] and [7]. Via color analytical techniques and phylogenetic comparisons, we show that cleaner fish are more likely to display a blue coloration, in addition to a yellow coloration, compared to noncleaner fish. Via theoretical vision models, we show that, from the perspective of potential signal receivers, blue is the most spectrally contrasting color against coral reef backgrounds, whereas yellow is most contrasting against blue water backgrounds or against black lateral stri! pes. Finally, behavioral experiments confirm that blue within the cleaner fish pattern attracts more client reef fish to cleaning stations. Cleaner fish have evolved some of the most conspicuous combinations of colors and patterns in the marine environment, and this is likely to underpin the success of the cleaner-client relationship on the reef. - Allelic Polymorphism within the TAS1R3 Promoter Is Associated with Human Taste Sensitivity to Sucrose
Fushan AA Simons CT Slack JP Manichaikul A Drayna D - Curr Biol 19(15):1288-1293 (2009)
Human sweet taste perception is mediated by the heterodimeric G protein-coupled receptor encoded by the TAS1R2 and TAS1R3 genes [1], [2], [3], [4], [5], [6] and [7]. Variation in these genes has been characterized [8], but the functional consequences of such variation for sweet perception are unknown. We found that two C/T single-nucleotide polymorphisms (SNPs) located at positions −1572 (rs307355) and −1266 (rs35744813) upstream of the TAS1R3 coding sequence strongly correlate with human taste sensitivity to sucrose and explain 16% of population variability in perception. By using a luciferase reporter assay, we demonstrated that the T allele of each SNP results in reduced promoter activity in comparison to the C alleles, consistent with the phenotype observed in humans carrying T alleles. We also found that the distal region of the TAS1R3 promoter harbors a composite cis-acting element that has a strong silencing effect on promoter activity. We conclude that the ! rs307355 and rs35744813 SNPs affect gene transcription by altering the function of this regulatory element. A worldwide population survey reveals that the T alleles of rs307355 and rs35744813 occur at lowest frequencies in European populations. We propose that inherited differences in TAS1R3 transcription account for a substantial fraction of worldwide differences in human sweet taste perception. - Reward Motivation Accelerates the Onset of Neural Novelty Signals in Humans to 85 Milliseconds
Bunzeck N Doeller CF Fuentemilla L Dolan RJ Duzel E - Curr Biol 19(15):1294-1300 (2009)
The neural responses that distinguish novel from familiar items in recognition memory tasks are remarkably fast in both humans and nonhuman primates. In humans, the earliest onsets of neural novelty effects emerge at about 150–200 ms after stimulus onset [1], [2], [3], [4] and [5]. However, in recognition memory studies with nonhuman primates, novelty effects can arise at as early as 70–80 ms [6] and [7]. Here, we address the possibility that this large species difference in onset latencies is caused experimentally by the necessity of using reward reinforcement to motivate the detection of novel or familiar items in nonhuman primates but not in humans. Via magnetoencephalography in humans, we show in two experiments that the onset of neural novelty signals is accelerated from 200 ms to 85 ms if correct recognition memory for either novel or familiar items is rewarded. Importantly, this acceleration is independent of whether the detection of the novel or the familia! r scenes is rewarded. Furthermore, this early novelty effect contributed to memory retrieval because neural reward responses, which were contingent upon novelty detection, followed 100 ms later. Thus, under the contextual influence of reward motivation, behaviorally relevant novelty signals emerge much faster than previously held possible in humans. - Flies Require Bilateral Sensory Input to Track Odor Gradients in Flight
Duistermars BJ Chow DM Frye MA - Curr Biol 19(15):1301-1307 (2009)
Fruit flies make their living "on the fly" in search of attractive food odors. Flies balance the strength of self-induced bilateral visual motion [1] and bilateral wind cues [2], but it is unknown whether they also use bilateral olfactory cues to track odors in flight. Tracking an odor gradient requires comparisons across spatially separated chemosensory organs and has been observed in several walking insects [3], [4] and [5], including Drosophila[6]. The olfactory antennae are separated by a fraction of a millimeter, and most sensory neurons project bilaterally and also symmetrically activate the first-order olfactory relay [7] and [8]; both properties would seem to constrain the capacity for gradient tracking. Nevertheless, using a modified flight simulator that enables maneuvers in the yaw axis [9], we found that flies readily steer directly toward a laterally positioned odor plume. This capability is abolished by occluding sensory input to one antenna. Mechanos! ensory input from the Johnston's organ and olfactory input from the third antennal segment cooperate to direct small-angle yaw turns up the plume gradient. We additionally show that sensory signals from the left antenna contribute disproportionately more to odor tracking than signals from the right, providing further evidence of sensory lateralization in invertebrates [10], [11], [12] and [13]. - Explicit Encoding of Multimodal Percepts by Single Neurons in the Human Brain
Quian Quiroga R Kraskov A Koch C Fried I - Curr Biol 19(15):1308-1313 (2009)
Different pictures of Marilyn Monroe can evoke the same percept, even if greatly modified as in Andy Warhol's famous portraits. But how does the brain recognize highly variable pictures as the same percept? Various studies have provided insights into how visual information is processed along the "ventral pathway," via both single-cell recordings in monkeys [1] and [2] and functional imaging in humans [3] and [4]. Interestingly, in humans, the same "concept" of Marilyn Monroe can be evoked with other stimulus modalities, for instance by hearing or reading her name. Brain imaging studies have identified cortical areas selective to voices [5] and [6] and visual word forms [7] and [8]. However, how visual, text, and sound information can elicit a unique percept is still largely unknown. By using presentations of pictures and of spoken and written names, we show that (1) single neurons in the human medial temporal lobe (MTL) respond selectively to representations of! the same individual across different sensory modalities; (2) the degree of multimodal invariance increases along the hierarchical structure within the MTL; and (3) such neuronal representations can be generated within less than a day or two. These results demonstrate that single neurons can encode percepts in an explicit, selective, and invariant manner, even if evoked by different sensory modalities. - The Conserved NDR Kinase Orb6 Controls Polarized Cell Growth by Spatial Regulation of the Small GTPase Cdc42
Das M Wiley DJ Chen X Shah K Verde F - Curr Biol 19(15):1314-1319 (2009)
The conserved NDR kinase regulates cell morphogenesis and polarized cell growth in different eukaryotic cells ranging from yeast to neurons [1], [2], [3] and [4]. Although studies have unraveled the mechanism of regulation of NDR kinase activity [4], the mechanism of morphology control by NDR and the effectors that mediate NDR function are unknown. Via a chemical genetic approach, we show that the fission yeast NDR homolog, Orb6 kinase, maintains polarized cell growth at the cell tips by spatially regulating the localization of Cdc42 GTPase, a key morphology regulator. Loss of Orb6 kinase activity leads to the recruitment of Cdc42 GTPase and the Cdc42-dependent formin For3, normally found only at the cell tips, to the cell sides. Furthermore, we show that loss of Orb6 kinase activity leads to ectopic lateral localization of the Cdc42 guanine nucleotide exchange factor (GEF) Gef1, but not of the other Cdc42 GEF, Scd1. Consistent with these observations, gef1 deletion su! ppresses the increased cell diameter phenotype of orb6 mutants. In contrast, the microtubule cytoskeleton and the localization of the microtubule-dependent polarity markers Tea1 and Tea4 are not altered by loss of Orb6 kinase activity. Our findings indicate that the conserved NDR kinase Orb6 regulates cell polarity by spatially restricting the localization and activity of Cdc42 GTPase. - The Mammalian Cos2 Homolog Kif7 Plays an Essential Role in Modulating Hh Signal Transduction during Development
Endoh-Yamagami S Evangelista M Wilson D Wen X Theunissen JW Phamluong K Davis M Scales SJ Solloway MJ de Sauvage FJ Peterson AS - Curr Biol 19(15):1320-1326 (2009)
The Hedgehog (Hh) signaling pathway regulates development in animals ranging from flies to humans. Although its framework is conserved, differences in pathway components have been reported [1], [2], [3] and [4]. A kinesin-like protein, Costal2 (Cos2), plays a central role in the Hh pathway in flies [3] and [5]. Knockdown of a zebrafish homolog of Cos2, Kif7, results in ectopic Hh signaling, suggesting that Kif7 acts primarily as a negative regulator of Hh signal transduction [6]. However, in vitro analysis of the function of mammalian Kif7 and the closely related Kif27 has led to the conclusion that neither protein has a role in Hh signaling [4]. Using Kif7 knockout mice, we demonstrate that mouse Kif7, like its zebrafish and Drosophila homologs, plays a role in transducing the Hh signal. We show that Kif7 accumulates at the distal tip of the primary cilia in a Hh-dependent manner. We also demonstrate a requirement for Kif7 in the efficient localization of Gli3 to cili! a in response to Hh and for the processing of Gli3 to its repressor form. These results suggest a role for Kif7 in coordinating Hh signal transduction at the tip of cilia and preventing Gli3 cleavage into a repressor form in the presence of Hh. - ANXUR1 and 2, Sister Genes to FERONIA/SIRENE, Are Male Factors for Coordinated Fertilization
Miyazaki S Murata T Sakurai-Ozato N Kubo M Demura T Fukuda H Hasebe M - Curr Biol 19(15):1327-1331 (2009)
In sexual reproduction, proper communication and cooperation between male and female organs and tissues are essential for male and female gametes to unite. In flowering plants, female sporophytic tissues and gametophytes direct a male pollen tube toward an egg apparatus, which consists of an egg cell and two synergid cells [1], [2], [3], [4] and [5]. The cell-cell communication between the pollen tube and the egg apparatus makes the tip of pollen tube rupture to release the sperm cell [6] and [7]. To detect male factors involved in this communication, we screened mutants of receptor-like kinases expressed in pollen tubes and characterized ANXUR1 (ANX1) and ANXUR2 (ANX2) genes. Here we report that pollen tubes of anx1/anx2 mutants ruptured before arriving at the egg apparatus, suggesting that ANX1 and ANX2 are male factors controlling pollen tube behavior by directing rupture at proper timing. Furthermore, ANX1 and ANX2 were the most closely related paralogs of a female! factor, FERONIA/SIRENE, controlling pollen tube behavior expressed in synergid cells [7], [8] and [9]. Our findings show that the coordinated behaviors of female and male reproductive apparatuses are regulated by these sister genes, whose duplication might play a role in the evolution of the fertilization system in flowering plants. - Lack of DREAM Protein Enhances Learning and Memory and Slows Brain Aging
- Curr Biol 19(15):1332 (2009)
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