Laterality and Flight: Concurrent Tests of Side-Bias and Optimality in Flying Tree Swallows

Behavioural side-bias occurs in many vertebrates, including birds as a result of hemispheric specialization and can be advantageous by improving response times to sudden stimuli and efficiency in multi-tasking. However, behavioural side-bias can lead to morphological asymmetries resulting in reduced performance for specific activities. For flying animals, wing asymmetry is particularly costly and it is unclear if behavioural side-biases will be expressed in flight; the benefits of quick response time afforded by side-biases must be balanced against the costs of less efficient flight due to the morphological asymmetry side-biases may incur. Thus, competing constraints could lead to context-dependent expression or suppression of side-bias in flight. In repeated flight trials through an outdoor tunnel with obstacles, tree swallows (Tachycineta bicolor) preferred larger openings, but we did not detect either individual or population-level side-biases. Thus, while observed behavioural side-biases during substrate-foraging and copulation are common in birds, we did not see such side-bias expressed in obstacle avoidance behaviour in flight. This finding highlights the importance of behavioural context for investigations of side-bias and hemispheric laterality and suggests both proximate and ultimate trade-offs between species-specific cognitive ecology and flight biomechanics

Psychology and Theodicy in Aquinas

Page range: 129-15

Electrospinning of poly(ethylene-co-vinyl alcohol) fibers

Solutions of poly(ethylene-co-vinyl alcohol) or EVOH, ranging in composition from 56 to 71wt% vinyl alcohol, can be readily electrospun at room temperature from solutions in 70% 2-propanol/water (rubbing alcohol). The solutions are prepared at 80°C and allowed to cool to room temperature. Interestingly, the solutions are not stable at room temperature and eventually the polymer precipitates after several hours. However, prior to precipitation, electrospinning is extensive and rapid, allowing coverage of fibers on various substrates, including a grounded metal plate, dielectrics interposed between the charged jet and the metal ground, and on the human body. Fiber diameters of ca. 0.2-8.0μm were obtained depending upon the solution concentration, an attractive range for tissue engineering, wound healing, and related applications. Electrospun EVOH mats have been shown to support the culturing of smooth muscle cells and fibroblasts. © 2002 Elsevier Science Ltd. All rights reserved

Aryl Rhodanines Specifically Inhibit Staphylococcal and Enterococcal Biofilm Formation▿ †

Staphylococcus epidermidis and Staphylococcus aureus are the leading causative agents of indwelling medical device infections because of their ability to form biofilms on artificial surfaces. Here we describe the antibiofilm activity of a class of small molecules, the aryl rhodanines, which specifically inhibit biofilm formation of S. aureus, S. epidermidis, Enterococcus faecalis, E. faecium, and E. gallinarum but not the gram-negative species Pseudomonas aeruginosa or Escherichia coli. The aryl rhodanines do not exhibit antibacterial activity against any of the bacterial strains tested and are not cytotoxic against HeLa cells. Preliminary mechanism-of-action studies revealed that the aryl rhodanines specifically inhibit the early stages of biofilm development by preventing attachment of the bacteria to surfaces

Two pole air gap electrospinning: Fabrication of highly aligned, three-dimensional scaffolds for nerve reconstruction

We describe the structural and functional properties of three-dimensional (3D) nerve guides fabricated from poly - caprolactone (PCL) using the air gap electrospinning process. This process makes it possible to deposit nano-to-micron diameter fibers into linear bundles that are aligned in parallel with the long axis of a cylindrical construct. By varying starting electrospinning conditions it is possible to modulate scaffold material properties and void space volume. The architecture of these constructs provides thousands of potential channels to direct axon growth. In cell culture functional assays, scaffolds composed of individual PCL fibers ranging from 400 to 1500 nm supported the penetration and growth of axons from rat dorsal root ganglion. To test the efficacy of our guide design we reconstructed 10 mm lesions in the rodent sciatic nerve with scaffolds that had fibers 1 μm in average diameter and void volumes \u3e90%. Seven weeks post implantation, microscopic examination of the regenerating tissue revealed dense, parallel arrays of myelinated and non-myelinated axons. Functional blood vessels were scattered throughout the implant. We speculate that end organ targeting might be improved in nerve injuries if axons can be directed to regenerate along specific tissue planes by a guide composed of 3D fiber arrays. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

Modern stromatolite phototrophic communities: a comparative study of procaryote and eucaryote phototrophs using variable chlorophyll fluorescence

Stromatolites are laminated organosedimentary structures formed by microbial communities, principally cyanobacteria although eucaryote phototrophs may also be involved in the construction of modern stromatolites. In this study, productivity and photophysiology of communities from stromatolites (laminated) and thrombolites (nonlaminated) were analysed using fluorescence imaging. Sub-samples of mats were excised at Highborne Cay, Bahamas, and cross-sectioned to simultaneously analyse surface, near-surface (1–2 mm), and deeper (2–10 mm) communities. Rapid light curve parameters and nonphotochemical downregulation showed distinct differences between phototroph communities, consistent with the reported quasi-succession of classic stromatolite mat types. Greater productivity was shown by cyanobacteria in Type 1 and Type 3 mats (first and final stage of the succession, Schizothrix gebeleinii and Solentia sp. respectively) and lower productivity within Type 2 mats (intermediate mat type). Eucaryote mat types, dominated by stalked (Striatella sp. and Licmophora sp.) and tube-dwelling (e.g. Nitzschia and Navicula spp.) diatoms, showed greater productivity than cyanobacteria communities, with the exception of Striatella (low productivity) and an unidentified coccoid cyanobacterium (high productivity). Findings indicate comparative variability between photosynthetically active procaryote and eucaryote sub-communities within stromatolites, with a pattern logically following the succession of ‘classic’ mat types, and lower than the productivity of eucaryote dominated ‘nonclassic’ mat types

Identification of a Small-Molecule Entry Inhibitor for Filoviruses▿ †

Ebola virus (EBOV) causes severe hemorrhagic fever, for which therapeutic options are not available. Preventing the entry of EBOV into host cells is an attractive antiviral strategy, which has been validated for HIV by the FDA approval of the anti-HIV drug enfuvirtide. To identify inhibitors of EBOV entry, the EBOV envelope glycoprotein (EBOV-GP) gene was used to generate pseudotype viruses for screening of chemical libraries. A benzodiazepine derivative (compound 7) was identified from a high-throughput screen (HTS) of small-molecule compound libraries utilizing the pseudotype virus. Compound 7 was validated as an inhibitor of infectious EBOV and Marburg virus (MARV) in cell-based assays, with 50% inhibitory concentrations (IC50s) of 10 μM and 12 μM, respectively. Time-of-addition and binding studies suggested that compound 7 binds to EBOV-GP at an early stage during EBOV infection. Preliminary Schrödinger SiteMap calculations, using a published EBOV-GP crystal structure in its prefusion conformation, suggested a hydrophobic pocket at or near the GP1 and GP2 interface as a suitable site for compound 7 binding. This prediction was supported by mutational analysis implying that residues Asn69, Leu70, Leu184, Ile185, Leu186, Lys190, and Lys191 are critical for the binding of compound 7 and its analogs with EBOV-GP. We hypothesize that compound 7 binds to this hydrophobic pocket and as a consequence inhibits EBOV infection of cells, but the details of the mechanism remain to be determined. In summary, we have identified a novel series of benzodiazepine compounds that are suitable for optimization as potential inhibitors of filoviral infection