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Current Biology: CB

Ferdinand Marlétaz, Katja T C A Peijnenburg, Taichiro Goto, Noriyuki Satoh, Daniel S Rokhsar
Chaetognaths (arrow worms) are an enigmatic group of marine animals whose phylogenetic position remains elusive, in part because they display a mix of developmental and morphological characters associated with other groups [1, 2]. In particular, it remains unclear whether they are a sister group to protostomes [1, 2], one of the principal animal superclades, or whether they bear a closer relationship with some spiralian phyla [3, 4]. Addressing the phylogenetic position of chaetognaths and refining our understanding of relationships among spiralians are essential to fully comprehend character changes during bilaterian evolution [5]...
January 8, 2019: Current Biology: CB
Yuki Shindo, Amanda A Amodeo
During zygotic genome activation (ZGA), the chromatin environment undergoes profound changes, including the formation of topologically associated domains, refinements in nucleosome positioning on promoters, and the emergence of heterochromatin [1-4]. In many organisms, including Drosophila, ZGA is associated with the end of a period of extremely rapid, exponential cleavage divisions that are facilitated by large maternally provided pools of nuclear components. It is therefore imperative that we understand how the supply of chromatin components relative to the exponentially increasing demand affects nuclear and chromatin composition during early embryogenesis...
January 8, 2019: Current Biology: CB
Shaohong Feng, Qi Fang, Ross Barnett, Cai Li, Sojung Han, Martin Kuhlwilm, Long Zhou, Hailin Pan, Yuan Deng, Guangji Chen, Anita Gamauf, Friederike Woog, Robert Prys-Jones, Tomas Marques-Bonet, M Thomas P Gilbert, Guojie Zhang
Human-induced environmental change and habitat fragmentation pose major threats to biodiversity and require active conservation efforts to mitigate their consequences. Genetic rescue through translocation and the introduction of variation into imperiled populations has been argued as a powerful means to preserve, or even increase, the genetic diversity and evolutionary potential of endangered species [1-4]. However, factors such as outbreeding depression [5, 6] and a reduction in available genetic diversity render the success of such approaches uncertain...
January 6, 2019: Current Biology: CB
Loren J Martin, Erinn L Acland, Chulmin Cho, Wiebke Gandhi, Di Chen, Elizabeth Corley, Basil Kadoura, Tess Levy, Sara Mirali, Sarasa Tohyama, Sana Khan, Leigh C MacIntyre, Erika N Carlson, Petra Schweinhardt, Jeffrey S Mogil
Pain memories are hypothesized to be critically involved in the transition of pain from an acute to a chronic state. To help elucidate the underlying neurobiological mechanisms of pain memory, we developed novel paradigms to study context-dependent pain hypersensitivity in mouse and human subjects, respectively. We find that both mice and people become hypersensitive to acute, thermal nociception when tested in an environment previously associated with an aversive tonic pain experience. This sensitization persisted for at least 24 hr and was only present in males of both species...
January 3, 2019: Current Biology: CB
Guillaume Jacquemet, Aki Stubb, Rafael Saup, Mitro Miihkinen, Elena Kremneva, Hellyeh Hamidi, Johanna Ivaska
Filopodia are adhesive cellular protrusions specialized in the detection of extracellular matrix (ECM)-derived cues. Although ECM engagement at focal adhesions is known to trigger the recruitment of hundreds of proteins ("adhesome") to fine-tune cellular behavior, the components of the filopodia adhesions remain undefined. Here, we performed a structured-illumination-microscopy-based screen to map the localization of 80 target proteins, linked to cell adhesion and migration, within myosin-X-induced filopodia...
January 3, 2019: Current Biology: CB
Jiayu Zhan, Robin A A Ince, Nicola van Rijsbergen, Philippe G Schyns
Over the past decade, extensive studies of the brain regions that support face, object, and scene recognition suggest that these regions have a hierarchically organized architecture that spans the occipital and temporal lobes [1-14], where visual categorizations unfold over the first 250 ms of processing [15-19]. This same architecture is flexibly involved in multiple tasks that require task-specific representations-e.g. categorizing the same object as "a car" or "a Porsche." While we partly understand where and when these categorizations happen in the occipito-ventral pathway, the next challenge is to unravel how these categorizations happen...
January 3, 2019: Current Biology: CB
Esther Klingler, Andres De la Rossa, Sabine Fièvre, Karthikeyan Devaraju, Philipp Abe, Denis Jabaudon
Neurons of the neocortex are organized into six radial layers, which have appeared at different times during evolution, with the superficial layers representing a more recent acquisition. Input to the neocortex predominantly reaches superficial layers (SL, i.e., layers (L) 2-4), while output is generated in deep layers (DL, i.e., L5-6) [1]. Intracortical connections, which bridge input and output pathways, are key components of cortical circuits because they allow the propagation and processing of information within the neocortex...
January 2, 2019: Current Biology: CB
Veronica E Scerra, M Gabriela Costello, Emilio Salinas, Terrence R Stanford
Choices of where to look are informed by perceptual judgments, which locate objects of current value or interest within the visual scene. This perceptual-motor transform is partly implemented in the frontal eye field (FEF), where visually responsive neurons appear to select behaviorally relevant visual targets and, subsequently, saccade-related neurons select the movements required to look at them. Here, we use urgent decision-making tasks to show (1) that FEF motor activity can direct accurate, visually informed choices in the complete absence of prior target-distracter discrimination by FEF visual responses and (2) that such discrimination by FEF visual cells shows an all-or-none reliance on the presence of stimulus attributes strongly associated with saliency-driven attentional allocation...
December 28, 2018: Current Biology: CB
Jelmer M Samplonius, Christiaan Both
Climate warming has altered phenologies of many taxa [1, 2], but the extent differs vastly between [3, 4] and within trophic levels [5-7]. Differential adjustment to climate warming within trophic levels may affect coexistence of competing species, because relative phenologies alter facilitative and competitive outcomes [8, 9], but evidence for this is scant [10, 11]. Here, we report on two mechanisms through which climate change may affect fatal interactions between two sympatric passerines, the resident great tit Parus major and the migratory pied flycatcher Ficedula hypoleuca, competing for nest sites...
December 28, 2018: Current Biology: CB
Pedro Guedes-Dias, Jeffrey J Nirschl, Nohely Abreu, Mariko K Tokito, Carsten Janke, Maria M Magiera, Erika L F Holzbaur
Neurons in the CNS establish thousands of en passant synapses along their axons. Robust neurotransmission depends on the replenishment of synaptic components in a spatially precise manner. Using live-cell microscopy and single-molecule reconstitution assays, we find that the delivery of synaptic vesicle precursors (SVPs) to en passant synapses in hippocampal neurons is specified by an interplay between the kinesin-3 KIF1A motor and presynaptic microtubules. Presynaptic sites are hotspots of dynamic microtubules rich in GTP-tubulin...
December 28, 2018: Current Biology: CB
Kari F Lenhart, Benjamin Capozzoli, Gwen S D Warrick, Stephen DiNardo
Tissue renewal becomes compromised with age. Although defects in niche and stem cell behavior have been implicated in promoting age-related decline, the causes of early-onset aging defects are unknown. We have identified an early consequence of aging in germline stem cells (GSCs) in the Drosophila testis. Aging disrupts the unique program of GSC cytokinesis, with GSCs failing to abscise from their daughter cells. Abscission failure significantly disrupts both self-renewal and the generation of differentiating germ cells...
December 27, 2018: Current Biology: CB
Claire Meissner-Bernard, Yulia Dembitskaya, Laurent Venance, Alexander Fleischmann
Odor memories are exceptionally robust and essential for animal survival. The olfactory (piriform) cortex has long been hypothesized to encode odor memories, yet the cellular substrates for olfactory learning and memory remain unknown. Here, using intersectional, cFos-based genetic manipulations ("Fos tagging"), we show that olfactory fear conditioning activates sparse and distributed ensembles of neurons in the mouse piriform cortex. We demonstrate that chemogenetic silencing of these Fos-tagged piriform ensembles selectively interferes with odor fear memory retrieval but does not compromise basic odor detection and discrimination...
December 24, 2018: Current Biology: CB
Giuseppe Facchetti, Benjamin Knapp, Ignacio Flor-Parra, Fred Chang, Martin Howard
How cell size is determined and maintained remains unclear, even in simple model organisms. In proliferating cells, cell size is regulated by coordinating growth and division through sizer, adder, or timer mechanisms or through some combination [1, 2]. Currently, the best-characterized example of sizer behavior is in fission yeast, Schizosaccharomyces pombe, which enters mitosis at a minimal cell size threshold. The peripheral membrane kinase Cdr2 localizes in clusters (nodes) on the medial plasma membrane and promotes mitotic entry [3]...
December 23, 2018: Current Biology: CB
Steffy B Manjila, Maria Kuruvilla, Jean-Francois Ferveur, Sanjay P Sane, Gaiti Hasan
Insect flight is a complex behavior that requires the integration of multiple sensory inputs with flight motor output. Although previous genetic studies identified central brain monoaminergic neurons that modulate Drosophila flight, neuro-modulatory circuits underlying sustained flight bouts remain unexplored. Certain classes of dopaminergic and octopaminergic neurons that project to the mushroom body, a higher integrating center in the insect brain, are known to modify neuronal output based on contextual cues and thereby organismal behavior...
December 22, 2018: Current Biology: CB
Stefanie S Schmieder, Claire E Stanley, Andrzej Rzepiela, Dirk van Swaay, Jerica Sabotič, Simon F Nørrelykke, Andrew J deMello, Markus Aebi, Markus Künzler
Intercellular distribution of nutrients and coordination of responses to internal and external cues via endogenous signaling molecules are hallmarks of multicellular organisms. Vegetative mycelia of multicellular fungi are syncytial networks of interconnected hyphae resulting from hyphal tip growth, branching, and fusion. Such mycelia can reach considerable dimensions and, thus, different parts can be exposed to quite different environmental conditions. Our knowledge about the mechanisms by which fungal mycelia can adjust nutrient gradients or coordinate their defense response to fungivores is scarce, in part due to limitations in technologies currently available for examining different parts of a mycelium over longer time periods at the microscopic level...
December 19, 2018: Current Biology: CB
Dayou Zhai, Javier Ortega-Hernández, Joanna M Wolfe, Xianguang Hou, Chunjie Cao, Yu Liu
Pancrustaceans boast impressive diversity, abundance, and ecological impact in the biosphere throughout the Phanerozoic [1]. Molecular clock estimates suggest an early Cambrian divergence for pancrustaceans [2, 3]. Despite the wealth of Palaeozoic exceptional fossiliferous deposits [4-7], the early evolution of Pancrustacea remains elusive given the difficulty of recognizing synapomorphies between Cambrian forms and extant representatives. Although early studies suggested crustacean affinities for Cambrian bivalved euarthropods [8-11], this view has fallen out of favor by recent reappraisals of their morphology [12-16]...
December 19, 2018: Current Biology: CB
Emilie W Olstad, Christa Ringers, Jan N Hansen, Adinda Wens, Cecilia Brandt, Dagmar Wachten, Emre Yaksi, Nathalie Jurisch-Yaksi
Motile cilia are miniature, propeller-like extensions, emanating from many cell types across the body. Their coordinated beating generates a directional fluid flow, which is essential for various biological processes, from respiration to reproduction. In the nervous system, ependymal cells extend their motile cilia into the brain ventricles and contribute to cerebrospinal fluid (CSF) flow. Although motile cilia are not the only contributors to CSF flow, their functioning is crucial, as patients with motile cilia defects develop clinical features, like hydrocephalus and scoliosis...
December 18, 2018: Current Biology: CB
Tom van der Valk, David Díez-Del-Molino, Tomas Marques-Bonet, Katerina Guschanski, Love Dalén
Many endangered species have experienced severe population declines within the last centuries [1, 2]. However, despite concerns about negative fitness effects resulting from increased genetic drift and inbreeding, there is a lack of empirical data on genomic changes in conjunction with such declines [3-7]. Here, we use whole genomes recovered from century-old historical museum specimens to quantify the genomic consequences of small population size in the critically endangered Grauer's and endangered mountain gorillas...
December 18, 2018: Current Biology: CB
Kaining Zhang, Charles D Chen, Ilya E Monosov
The basal forebrain (BF) is a principal source of modulation of the neocortex [1-6] and is thought to regulate cognitive functions such as attention, motivation, and learning by broadcasting information about salience [2, 3, 5, 7-19]. However, events can be salient for multiple reasons-such as novelty, surprise, or reward prediction errors [20-24]-and to date, precisely which salience-related information the BF broadcasts is unclear. Here, we report that the primate BF contains at least two types of neurons that often process salient events in distinct manners: one with phasic burst responses to cues predicting salient events and one with ramping activity anticipating such events...
December 18, 2018: Current Biology: CB
Phillip J Marlow, Scott W J Mooney, Barton L Anderson
The human visual system is remarkably adept at extracting the three-dimensional (3D) shape of surfaces from images of smoothly shaded surfaces (shape from shading). Most research into this remarkable perceptual ability has focused on understanding how the visual system derives a specific representation of 3D shape when it is known (or assumed) that shading and self-occluding contours are the sole causes of image structure [1-11]. But there is an even more fundamental problem that must be solved before any such analysis can take place: how does the visual system determine when it's viewing a shaded surface? Here, we present theoretical analyses showing that there is statistically reliable information generated along the bounding contours of smoothly curved surfaces that the visual system uses to identify surface shading...
December 17, 2018: Current Biology: CB
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