Showing 401 - 410 of 733 Items
Pheromones enhance somatosensory processing in newt brains through a vasotocin-dependent mechanism
Date: 2008-07-22
Creator: R. R. Thompson, P. S. Dickinson, J. D. Rose, K. A. Dakin, G. M., Civiello, A. Segerdahl, R. Bartlett
Access: Open access
- We tested whether the sex pheromones that stimulate courtship clasping in male roughskin newts do so, at least in part, by amplifying the somatosensory signals that directly trigger the motor pattern associated with clasping and, if so, whether that amplification is dependent on endogenous vasotocin (VT). Female olfactory stimuli increased the number of action potentials recorded in the medulla of males in response to tactile stimulation of the cloaca, which triggers the clasp motor reflex, as well as to tactile stimulation of the snout and hindlimb. That enhancement was blocked by exposing the medulla to a V1a receptor antagonist before pheromone exposure. However, the antagonist did not affect medullary responses to tactile stimuli in the absence of pheromone exposure, suggesting that pheromones amplify somatosensory signals by inducing endogenous VT release. The ability of VT to couple sensory systems together in response to social stimulation could allow this peptide to induce variable behavioural outcomes, depending on the immediate context of the social interaction and thus on the nature of the associated stimuli that are amplified. If widespread in vertebrates, this mechanism could account for some of the behavioural variability associated with this and related peptides both within and across species. © 2008 The Royal Society.
Entanglement sharing among quantum particles with more than two orthogonal states
Date: 2002-01-01
Creator: Kenneth A. Dennison, William K. Wootters
Access: Open access
- The entanglement sharing among quantum particles was discussed in a system consisting of n d-dimensional quantum particles. The entanglement between each pair was attempted to get optimized. A three particles system was also considered and results showed that the particles shared a greater fraction of their entanglement capacity as the dimension d increased.
Comparison between the fCCZ4 and BSSN formulations of Einstein equations in spherical polar coordinates
Date: 2015-01-01
Creator: N. Sanchis-Gual, P.J. Montero, J.A. Font, E. Müller, T.W., Baumgarte
Access: Open access
Characterization of plexinA and two distinct semaphorin1a transcripts in the developing and adult cricket Gryllus bimaculatus
Date: 2020-03-01
Creator: Hadley W. Horch, Sara B. Spicer, Isabel I.C. Low, Colby T. Joncas, Eleanor D., Quenzer, Hikmah Okoya, Lisa M. Ledwidge, Harrison P. Fisher
Access: Open access
- Guidance cues act during development to guide growth cones to their proper targets in both the central and peripheral nervous systems. Experiments in many species indicate that guidance molecules also play important roles after development, though less is understood about their functions in the adult. The Semaphorin family of guidance cues, signaling through Plexin receptors, influences the development of both axons and dendrites in invertebrates. Semaphorin functions have been extensively explored in Drosophila melanogaster and some other Dipteran species, but little is known about their function in hemimetabolous insects. Here, we characterize sema1a and plexA in the cricket Gryllus bimaculatus. In fact, we found two distinct predicted Sema1a proteins in this species, Sema1a.1 and Sema1a.2, which shared only 48% identity at the amino acid level. We include a phylogenetic analysis that predicted that many other insect species, both holometabolous and hemimetabolous, express two Sema1a proteins as well. Finally, we used in situ hybridization to show that sema1a.1 and sema1a.2 expression patterns were spatially distinct in the embryo, and both roughly overlap with plexA. All three transcripts were also expressed in the adult brain, mainly in the mushroom bodies, though sema1a.2 was expressed most robustly. sema1a.2 was also expressed strongly in the adult thoracic ganglia while sema1a.1 was only weakly expressed and plexA was undetectable.
Exchange Rate Regimes and Nominal Wage Comovements in a Dynamic Ricardian Model
Date: 2013-10-28
Creator: Yao Tang, Yoshinori Kurokawa, Jiaren Pang
Access: Open access
- We construct a dynamic Ricardian model of trade with money and nominal exchange rate. The model implies that the nominal wages of the trading countries are more likely to exhibit stronger positive comovements when the countries fix their bilateral exchange rates. Panel regression results based on data from OECD countries from 1973 to 2012 suggest that countries in the European Monetary Union (EMU) experienced stronger positive wage comovements with their main trade partners. When we restrict the regression to the subsample of the EMU countries, we find a significant increase in wage comovements after these countries joined the EMU in 1999 compared to the pre-euro era. In comparison, when the sample is restricted to the non-EMU countries, we find no evidence that non-currency union pegs affected the wage comovements.
Large-scale chromosomal changes and associated fitness consequences in pathogenic fungi
Date: 2014-01-01
Creator: Anja Forche
Access: Open access
- Pathogenic fungi encounter many different host environments to which they must adapt rapidly to ensure growth and survival. They also must be able to cope with alterations in established niches during long-term persistence in the host. Many eukaryotic pathogens have evolved a highly plastic genome, and large-scale chromosomal changes including aneuploidy, and loss of heterozygosity (LOH) can arise under various in vitro and in vivo stresses. Both aneuploidy and LOH can arise quickly during a single cell cycle, and it is hypothesized that they provide a rapid, albeit imprecise, solution to adaptation to stress until better and more refined solutions can be acquired by the organism. While LOH, with the extreme case of haploidization in Candida albicans, can purge the genome from recessive lethal alleles and/or generate recombinant progeny with increased fitness, aneuploidy, in the absence or rarity of meiosis, can serve as a non-Mendelian mechanism for generating genomic variation. © Springer Science+Business Media 2014.
Live imaging and biophysical modeling support a button-based mechanism of somatic homolog pairing in Drosophila
Date: 2021-06-01
Creator: Myron Child, Jack R. Bateman, Amir Jahangiri, Armando Reimer, Nicholas C., Lammers, Nica Sabouni, Diego Villamarin, Grace C. McKenzie-Smith, Justine E. Johnson, Daniel Jost, Hernan G. Garcia
Access: Open access
- 3D eukaryotic genome organization provides the structural basis for gene regulation. In Drosophila melanogaster, genome folding is characterized by somatic homolog pairing, where homologous chromosomes are intimately paired from end to end; however, how homologs identify one another and pair has remained mysterious. Recently, this process has been proposed to be driven by specifically interacting “buttons” encoded along chromosomes. Here, we turned this hypothesis into a quantitative biophysical model to demonstrate that a button-based mechanism can lead to chromosome-wide pairing. We tested our model using live-imaging measurements of chromosomal loci tagged with the MS2 and PP7 nascent RNA labeling systems. We show solid agreement between model predictions and experiments in the pairing dynamics of individual homologous loci. Our results strongly support a button-based mechanism of somatic homolog pairing in Drosophila and provide a theoretical framework for revealing the molecular identity and regulation of buttons.
Locating noctiluca miliaris in the arabian sea: An optical proxy approach
Date: 2014-01-01
Creator: Patricia S. Thibodeau, Collin S. Roesler, Susan L. Drapeau, S. G. Prabhu Matondkar, Joaquim I., Goes, P. Jeremy Werdell
Access: Open access
- Coincident with shifting monsoon weather patterns over India, the phytoplankter Noctiluca miliaris has recently been observed to be dominating phytoplankton blooms in the northeastern Arabian Sea during the winter monsoons. Identifying the exact environmental and/or ecological conditions that favor this species has been hampered by the lack of concurrent environmental and biological observations on time and space scales relevant to ecologic and physiologic processes. We present a bio-optical proxy for N. miliaris measured on highly resolved depth scales coincident with hydrographic observations with the goal to identify conducive hydrographic conditions for the bloom. The proxy is derived from multichannel excitation chlorophyll a fluorescence and is validated with microscopy, pigment composition, and spectral absorption. Phytoplankton populations dominated by either diatoms or other dinoflagellates were additionally discerned. N. miliaris populations in full bloom were identified offshore in low-nutrient and low–N:P ratio surface waters within a narrow temperature and salinity range. These populations transitioned to high-biomass diatom-dominated coastal upwelling populations. A week later, the N. miliaris blooms were observed in declining phase, transitioning to very-low-biomass populations of non–N. miliaris dinoflagellates. There were no clear hydrographic conditions uniquely associated with the N. miliaris populations, although N. miliaris was not found in the upwelling or extremely oligotrophic waters. Taxonomic transitions were not discernible in the spatial structure of the bloom as identified by the ocean color Chl imagery, indicating that in situ observations may be necessary to resolve community structure, particularly for populations below the surface.
Measuring Creative Performance of Teams Through Dynamic Semantic Social Network Analysis
Date: 2013-04-12
Creator: Peter Gloor
Access: Open access
- In this project we compare communication structure and content exchanged by members of creative, interdisciplinary teams of medical researchers, physicians, patients and caretakers with their creative output. We find that longitudinal social networking patterns and word usage predict creative performance. We collected the e-mail archives of 60 members of a community of researchers working on 12 projects improving various aspects of the daily lives of patients of Crohn’s disease. Our results indicate that more creative projects show a decrease in group density, while more actors are involved, and more emails are exchanged, suggesting that a more successful project attracts more attention from many different people. We also found that members of more creative projects use more emotional language, which gets more focused over time.