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1005 Janelia Publications

Showing 1-10 of 1005 results
09/26/16 | Flight of the dragonflies and damselflies.
Bomphrey RJ, Nakata T, Henningsson P, Lin H
Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 2016 Sep 26;371(1704):. doi: 10.1098/rstb.2015.0389

This work is a synthesis of our current understanding of the mechanics, aerodynamics and visually mediated control of dragonfly and damselfly flight, with the addition of new experimental and computational data in several key areas. These are: the diversity of dragonfly wing morphologies, the aerodynamics of gliding flight, force generation in flapping flight, aerodynamic efficiency, comparative flight performance and pursuit strategies during predatory and territorial flights. New data are set in context by brief reviews covering anatomy at several scales, insect aerodynamics, neuromechanics and behaviour. We achieve a new perspective by means of a diverse range of techniques, including laser-line mapping of wing topographies, computational fluid dynamics simulations of finely detailed wing geometries, quantitative imaging using particle image velocimetry of on-wing and wake flow patterns, classical aerodynamic theory, photography in the field, infrared motion capture and multi-camera optical tracking of free flight trajectories in laboratory environments. Our comprehensive approach enables a novel synthesis of datasets and subfields that integrates many aspects of flight from the neurobiology of the compound eye, through the aeromechanical interface with the surrounding fluid, to flight performance under cruising and higher-energy behavioural modes.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'.

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08/17/16 | Membrane dynamics of dividing cells imaged by lattice light-sheet microscopy.
Aguet F, Upadhyayula S, Gaudin R, Chou Y, Cocucci E, He K, Chen B, Mosaliganti K, Pasham M, Skillern W, Legant WR, Liu T, Findlay G, Marino E, Danuser G, Megason S, Betzig E, Kirchhausen T
Molecular Biology of the Cell. 2016 Aug 17:. doi: 10.1091/mbc.E16-03-0164

Membrane remodeling is an essential part for transfer of components to and from the cell surface and membrane-bound organelles, and for changes in cell shape, particularly critical during cell division. Earlier analyses, based on classical optical live-cell imaging, mostly restricted by technical necessity to the attached bottom surface, showed persistent formation of endocytic clathrin pits and vesicles during mitosis. Taking advantage of the resolution, speed, and non-invasive illumination of the newly developed lattice light sheet fluorescence microscope, we reexamined their assembly dynamics over the entire cell surface and showed that clathrin pits form at a lower rate during late mitosis. Full-cell imaging measurements of cell surface area and volume throughout the cell cycle of single cells in culture and in zebrafish embryos showed that the total surface increased rapidly during the transition from telophase to cytokinesis, whereas cell volume increased slightly in metaphase and remained relatively constant during cytokinesis. These applications demonstrate the advantage of lattice light sheet microscopy and enable a new standard for imaging membrane dynamics in single cells and in multicellular assemblies.

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08/17/16 | Satb2 stations neurons along reflex arcs.
Hantman AW, Kaltschmidt JA
Neuron. 2016 Aug 17;91(4):711-3. doi: 10.1016/j.neuron.2016.08.005

The nociceptive flexor withdrawal reflex has an august place in the history of neuroscience. In this issue of Neuron, Hilde et al. (2016) advance our understanding of this reflex by characterizing the molecular identity and circuit connectivity of component interneurons. They assess how a DNA-binding factor Satb2 controls cell position, molecular identity, pre-and postsynaptic targeting, and function of a population of inhibitory sensory relay interneurons that serve to integrate both proprioceptive and nociceptive afferent information.

The nociceptive flexor withdrawal reflex has an august place in the history of neuroscience. In this issue of Neuron, Hilde et al. (2016) advance our understanding of this reflex by characterizing the molecular identity and circuit connectivity of component interneurons. They assess how a DNA-binding factor Satb2 controls cell position, molecular identity, pre-and postsynaptic targeting, and function of a population of inhibitory sensory relay interneurons that serve to integrate both proprioceptive and nociceptive afferent information.

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08/15/16 | Targeted manipulation of neuronal activity in behaving adult flies.
Hampel S, Seeds AM
PeerJ Preprints. 2016 Aug 15;4:e2354v1. doi: 10.7287/peerj.preprints.2354v1

The ability to control the activity of specific neurons in freely behaving animals provides an effective way to probe the contributions of neural circuits to behavior. Wide interest in studying principles of neural circuit function using the fruit fly Drosophila melanogaster has fueled the construction of an extensive transgenic toolkit for performing such neural manipulations. Here we describe approaches for using these tools to manipulate the activity of specific neurons and assess how those manipulations impact the behavior of flies. We also describe methods for examining connectivity among multiple neurons that together form a neural circuit controlling a specific behavior. This work provides a resource for researchers interested in examining how neurons and neural circuits contribute to the rich repertoire of behaviors performed by flies.

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08/10/16 | Natural courtship song variation caused by an intronic retroelement in an ion channel gene.
Ding Y, Berrocal A, Morita T, Longden KD, Stern DL
Nature. 2016 Aug 10:. doi: 10.1038/nature19093

Animal species display enormous variation for innate behaviours, but little is known about how this diversity arose. Here, using an unbiased genetic approach, we map a courtship song difference between wild isolates of Drosophila simulans and Drosophila mauritiana to a 966 base pair region within the slowpoke (slo) locus, which encodes a calcium-activated potassium channel. Using the reciprocal hemizygosity test, we confirm that slo is the causal locus and resolve the causal mutation to the evolutionarily recent insertion of a retroelement in a slo intron within D. simulans. Targeted deletion of this retroelement reverts the song phenotype and alters slo splicing. Like many ion channel genes, slo is expressed widely in the nervous system and influences a variety of behaviours; slo-null males sing little song with severely disrupted features. By contrast, the natural variant of slo alters a specific component of courtship song, illustrating that regulatory evolution of a highly pleiotropic ion channel gene can cause modular changes in behaviour.

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08/05/16 | Drosophila larval to pupal switch under nutrient stress requires IP3R/Ca(2+) signalling in glutamatergic interneurons.
Jayakumar S, Richhariya S, Reddy OVenkateswara, Texada MJ, Hasan G
eLife. 2016 Aug 5;5:. doi: 10.7554/eLife.17495

Neuronal circuits are known to integrate nutritional information, but the identity of the circuit components is not completely understood. Amino acids are a class of nutrients that are vital for the growth and function of an organism. Here, we report a neuronal circuit that allows Drosophila larvae to overcome amino acid deprivation and pupariate. We find that nutrient stress is sensed by the class IV multidendritic cholinergic neurons. Through live calcium imaging experiments, we show that these cholinergic stimuli are conveyed to glutamatergic neurons in the ventral ganglion through mAChR. We further show that IP3R-dependent calcium transients in the glutamatergic neurons convey this signal to downstream medial neurosecretory cells (mNSCs). The circuit ultimately converges at the ring gland and regulates expression of ecdysteroid biosynthetic genes. Activity in this circuit is thus likely to be an adaptation that provides a layer of regulation to help surpass nutritional stress during development.

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08/03/16 | Real-time imaging of Huntingtin aggregates diverting target search and gene transcription.
Li L, Liu H, Dong P, Li D, Legant WR, Grimm JB, Lavis LD, Betzig E, Tjian R, Liu Z
eLife. 2016 Aug 03;5:. doi: 10.7554/eLife.17056

The presumptive altered dynamics of transient molecular interactions in vivo contributing to neurodegenerative diseases have remained elusive. Here, using single-molecule localization microscopy, we show that disease-inducing Huntingtin (mHtt) protein fragments display three distinct dynamic states in living cells - 1) fast diffusion, 2) dynamic clustering and 3) stable aggregation. Large, stable aggregates of mHtt exclude chromatin and form 'sticky' decoy traps that impede target search processes of key regulators involved in neurological disorders. Functional domain mapping based on super-resolution imaging reveals an unexpected role of aromatic amino acids in promoting protein-mHtt aggregate interactions. Genome-wide expression analysis and numerical simulation experiments suggest mHtt aggregates reduce transcription factor target site sampling frequency and impair critical gene expression programs in striatal neurons. Together, our results provide insights into how mHtt dynamically forms aggregates and disrupts the finely-balanced gene control mechanisms in neuronal cells.

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08/02/16 | The genome of the crustacean Parhyale hawaiensis: a model for animal development, regeneration, immunity and lignocellulose digestion.
Kao D, Lai AG, Stamataki E, Rosic S, Konstantinides N, Jarvis E, Di Donfrancesco A, Pouchkina-Stantcheva N, Semon M, Grillo M, Bruce H, Kumar S, Siwanowicz I, Le A, Lemire A, Extavour C, Browne W, Wolff C, Averof M, et al
bioRxiv. 2016 Aug 02:065789. doi: 10.1101/065789

Parhyale hawaiensis is a blossoming model system for studies of developmental mechanisms and more recently adult regeneration. We have sequenced the genome allowing annotation of all key signaling pathways, small non-coding RNAs and transcription factors that will enhance ongoing functional studies. Parhayle is a member of the Malacostraca, which includes crustacean food crop species. We analysed the immunity related genes of Parhyale as an important comparative system for these species, where immunity related aquaculture problems have increased as farming has intensified. We also find that Parhyale and other species within Multicrustacea contain the enzyme sets necessary to perform lignocellulose digestion (wood eating), suggesting this ability may predate the diversification of this lineage. Our data provide an essential resource for further development of the Parhyale model. The first Malacostracan genome sequence will underpin ongoing comparative work in important food crop species and research investigating lignocellulose as energy source.

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08/01/16 | Midbody remnant licenses primary cilia formation in epithelial cells.
Ott CM
The Journal of Cell Biology. 2016 Aug 1;214(3):237-9. doi: 10.1083/jcb.201607046

Tethered midbody remnants dancing across apical microvilli, encountering the centrosome, and beckoning forth a cilium-who would have guessed this is how polarized epithelial cells coordinate the end of mitosis and the beginning of ciliogenesis? New evidence from Bernabé-Rubio et al. (2016. J. Cell Biol supports this emerging model.

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07/29/16 | Bright photoactivatable fluorophores for single-molecule imaging.
Lavis LD, Grimm JB, English BP, Choi H, Muthusamy AK, Mehl BP, Dong P, Brown TA, Lippincott-Schwartz J, Liu Z, Lionnet T
bioRxiv. 2016 Jul 29:066779. doi: 10.1101/066779

Small molecule fluorophores are important tools for advanced imaging experiments. The development of self-labeling protein tags such as the HaloTag and SNAP-tag has expanded the utility of chemical dyes in live-cell microscopy. We recently described a general method for improving the brightness and photostability of small, cell-permeable fluorophores, resulting in the novel azetidine-containing "Janelia Fluor" (JF) dyes. Here, we refine and extend the utility of the JF dyes by synthesizing photoactivatable derivatives that are compatible with live cell labeling strategies. These compounds retain the superior brightness of the JF dyes once activated, but their facile photoactivation also enables improved single-particle tracking and localization microscopy experiments.

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