Recruitment patterns and processes in Canadian parkland mallards

An improved ability to assess whether individuals have been added through immigration or natality and lost through emigration or mortality could alleviate several problems in population ecology. Fortunately, advances in stable isotope techniques now allow the movements of individuals to be retraced from tissue values and provide an opportunity to link information about the origins of individuals with demographic rates so that questions about the significance of dispersal can be assessed. I used such an approach by combining feather isotope information with demographic rates derived from capture-mark-recapture of individual mallards (Anas platyrhynchos) breeding in the Canadian aspen parklands, at multiple spatiotemporal scales, to answer questions about population persistence, settling patterns by dispersers, and the fitness of immigrant birds relative to residents. Feather isotope (ä34S, äD, ä15N, and ä13C) values from an independent sample of flightless mallard ducklings sampled from across the mid-continent breeding range was used to validate an existing model used for origin assignments. Spatial resolution analysis within the mid-continent mallard breeding range generally showed a loss in prediction when attempting to assign individuals to more narrowly separated geographic origins among boreal, aspen parkland and prairie regions. For feather äD, spatial resolution may be limited by temporal patterns of local climatic events that produce variability in consumer tissue values. Thus, the use of multiple feather isotope signals would provide more reliable information about the origin of individuals for addressing questions about long-distance dispersal in yearling mallards. Demographic rescue in an apparent population “sink” near Minnedosa, Manitoba, Canada, was due to elevated survival rates from a highly productive group of nesting female mallards using nest tunnels (i.e., an artificial nesting structure) and recruitment of yearling females having natal origins within the aspen parklands. There was little evidence that immigration by yearling females dispersing long-distances was important to annual population growth rates. Consistently high annual survival rates of adult females using nest tunnels lowered the recruitment rates needed for population stability. While tunnel-origin and within-region recruitment of yearling females were nearly equally important to local population growth rate, fine-scale limitations of isotopic origin assignments prevented further assessment of where recruits originated from within the aspen parkland region. Factors related to breeding area settling patterns of yearling females are not well understood despite implications to local population dynamics. The likelihood that immigrant yearling females would settle in a parkland breeding area was positively correlated with local breeding-pair density and the amount of perennial nest cover, but was negatively correlated with the amount of wetlands. Although these relationships were not well estimated, they are most consistent a hypothesis that females were attracted to breeding sites by conspecific cues rather than avoidance. Immigrants comprised an average of 9% (range: 0 – 39% over 22 sites) of yearling recruits; most had natal origins in the U.S. prairie pothole region but a non-trivial number originated from the boreal forest, indicating a high degree of connectedness among breeding regions resulting from long-distance natal dispersal. One of the most frequent explanations for strong site fidelity in breeding female ducks is that females benefit from site familiarity. However, evidence for differential reproductive success between immigrant and resident yearling females was weak, On sites with favourable wetland conditions and low breeding-pair densities immigrant females were more likely to breed and nest successfully than were residents whereas under opposite wetland and pair conditions, resident females were favoured. Thus, the costs and benefits of a natal dispersal decision seemed to vary with social context and environmental conditions, and further work is needed to clarify these processes

Spatial and temporal changes in seasonal range attributes in a declining barren-ground caribou herd

From 1996 to 2015 the Bathurst caribou herd has declined from approximately 349,000 to 20,000 animals. Aboriginal traditional knowledge (TK) has recently observed the later arrival of the herd below the treeline, an attribute of the autumn range. Science also predicts that seasonal range attributes (e.g., area, location) likely vary with population size, and perhaps climate. We used Aboriginal TK and science to identify several seasonal range attributes that were ex­amined for changes through time (decreasing population abundance). Attributes of seasonal ranges for female Bathurst caribou were calculated using satellite radio-collar data from January 1996 through October 2013. Climate data from CircumArctic Rangifer Monitoring and Assessment Network were analyzed for trends from 1979 to 2009. Analyses showed a significant decrease in the area of post-calving and autumn ranges, but no changes in winter and spring ranges. Results supported Aboriginal TK that female caribou have shifted the autumn range farther from the treeline and moved into the forest later in the year. Analysis of climate variables found no trends at the spatio-temporal scale of the post-calving to autumn ranges. Working hypotheses to explain these patterns, which are not mutually exclusive, include reduced predation risk, increased use of core areas at lower population density, and greater utilization of areas of taiga where arboreal and ground lichen availability and accessibility are relatively higher than in the forest. This analysis demonstrates how including Aboriginal TK can lead to stronger connections and results, with potential to provide new and different insights for further investigations

Fundamental limits on constraining primordial non-Gaussianity

We study the cosmic variance limit on constraining primordial non-Gaussianity for a variety of theory-motivated shapes. We consider general arguments for 2D and 3D surveys, with a particular emphasis on the CMB. A scale-invariant N-point correlator can be measured with a signal-to-noise that naively scales with the square root of the number of observed modes. This intuition generally fails for two reasons. First, the signal-to-noise scaling is reduced due to the blurring of the last scattering surface at short distances. This blurring is caused by the combination of projection and damping, but the loss of signal is not due to exponential decay, as both signal and noise are equally damped. Second, the behavior of the N-point correlator in the squeezed and collapsed (for N > 3) limits can enhance the scaling of the signal-to-noise with the resolution, even with a reduced range of momenta probing these limits. We provide analytic estimates for all N-point correlators. We show that blurring affects equilateral-like shapes much more than squeezed ones. We discuss under what conditions the optimistic scalings in the collapsed limit can be exploited. Lastly, we confirm our analytical estimates with numerical calculations of the signal-to-noise for local, orthogonal and equilateral bispectra, and local trispectra. We also show that adding polarization to intensity data enhances the scaling for equilateral-like spectra

Coordinated Rearrangements between Cytoplasmic and Periplasmic Domains of the Membrane Protein Complex ExbB-ExbD of Escherichia coli

SummaryGram-negative bacteria rely on the ExbB-ExbD-TonB system for the import of essential nutrients. Despite decades of research, the stoichiometry, subunit organization, and mechanism of action of the membrane proteins of the Ton system remain unclear. We copurified ExbB with ExbD as an ∼240 kDa protein-detergent complex, measured by light scattering and by native gels. Quantitative Coomassie staining revealed a stoichiometry of ExbB4-ExbD2. Negative stain electron microscopy and 2D analysis showed particles of ∼10 nm diameter in multiple structural states. Nanogold labeling identified the position of the ExbD periplasmic domain. Random conical tilt was used to reconstruct the particles in three structural states followed by sorting of the single particles and refinement of each state. The different states are interpreted by coordinated structural rearrangements between the cytoplasmic domain and the periplasmic domain, concordant with in vivo predictions

Siderophore Transport through Escherichia coli Outer Membrane Receptor FhuA with Disulfide-tethered Cork and Barrel Domains

The hydroxamate siderophore receptor FhuA is a TonB-dependent outer membrane protein of Escherichia coli composed of a C-terminal 22-stranded -barrel occluded by an N-terminal globular cork domain. During siderophore transport into the periplasm, the FhuA cork domain has been proposed to undergo conformational changes that allow transport through the barrel lumen; alternatively, the cork may be completely displaced from the barrel. To probe such changes, site-directed cysteine mutants in the cork domain (L109C and Q112C) and in the barrel domain (S356C and M383C) were created within the putative siderophore transport pathway. Molecular modeling predicted that the double cysteine mutants L109C/S356C and Q112C/M383C would form disulfide bonds, thereby tethering the cork and barrel domains. The double cysteine FhuA mutants were denatured under nonreducing conditions and fluorescently labeled with thiol-specific Oregon Green maleimide. Subsequent SDS-PAGE analysis revealed two distinct species: FhuA containing a disulfide bond and FhuA with free sulfhydryl groups. To address the role of the putative siderophore transport pathway and to evaluate possible rearrangements of the cork domain during ferricrocin transport, disulfide bond formation was enhanced by an oxidative catalyst. Cells containing double cysteine FhuA mutants that were subjected to oxidation during ferricrocin transport exhibited disulfide bond formation to near completion. After disulfide tethering of the cork to the barrel, ferricrocin transport was equivalent to transport by untreated cells. These results demonstrate that blocking the putative siderophore transport pathway does not abrogate ferricrocin uptake. We propose that, during siderophore transport through FhuA, the cork domain remains within the barrel rather than being displaced

Pain associated with pressure injury: A qualitative study of community-based, home-dwelling individuals

© 2017 John Wiley & Sons Ltd. Aims: The aim of this study was to provide deep insights into the pain associated with pressure injuries in home-dwelling individuals using narrative accounts. Background: Pressure injuries or pressure ulcers are burdensome and costly. Prevalence data, surveys and systematic reviews demonstrate that pain associated with pressure injury is widespread, but voices of home-dwelling patients have remained largely unheard. Design: Concurrent mixed methods case study of a UK community of approximately 50,000 adults. Methods: Qualitative interviews, conducted in 2016, of 12 home-dwelling adult participants with a current pressure injury (n = 10), or a recently healed pressure injury (n = 2). Findings: Pain had an adverse impact on activities of daily living, mobility and sleep. Participants described days that were clouded in pain; a pain they felt was poorly understood and often out of control. Thematic content analysis revealed two major themes; these are: Poorly controlled pain: “I just want the pain to go away”; and, Uncertainty for the future: “it almost seems insurmountable.”. Conclusion: Findings of our study support the need to develop an appropriate assessment tool for pressure injury patients in the community to enable healthcare professionals and patients to recognize and manage pressure injury-related pain effectively

Health service provision and the use of pressure-redistributing devices: mixed methods study of community dwelling individuals with pressure injuries

© 2017 Informa UK Limited, trading as Taylor & Francis Group. Background: Health care within the home setting is a vital and growing component of pressure injury (PI) prevention and management. Objectives: To describe the use of health services and pressure-redistributing devices in community dwelling patients with PI’s. Design: Mixed-methods collective case study of a defined, diverse geographic postcode area in the United Kingdom. Methods: Quantitative retrospective analysis of electronic and paper medical records of adult PI patients from 2015 district nursing reports. Qualitative semi-structured interviews of community dwelling adult patients receiving, or received, treatment for PI in 2016. Results: Mandatory reports (n = 103) revealed that 90 patients were supplied with a variety of pressure-redistributing devices but only one-third of patients used the equipment as recommended. Qualitative interviews (n = 12), reported to COREQ guidelines, revealed that patients felt reliant on community health services, and were concerned about the consistency of their care. Conclusions: Authentic patient involvement is required to provide care and interventions that are acceptable to PI patients and can be incorporated into self-care strategies and effectively monitored

Microarray-based comparative genomic profiling of reference strains and selected Canadian field isolates of Actinobacillus pleuropneumoniae

<p>Abstract</p> <p>Background</p> <p><it>Actinobacillus pleuropneumoniae</it>, the causative agent of porcine pleuropneumonia, is a highly contagious respiratory pathogen that causes severe losses to the swine industry worldwide. Current commercially-available vaccines are of limited value because they do not induce cross-serovar immunity and do not prevent development of the carrier state. Microarray-based comparative genomic hybridizations (M-CGH) were used to estimate whole genomic diversity of representative <it>Actinobacillus pleuropneumoniae </it>strains. Our goal was to identify conserved genes, especially those predicted to encode outer membrane proteins and lipoproteins because of their potential for the development of more effective vaccines.</p> <p>Results</p> <p>Using hierarchical clustering, our M-CGH results showed that the majority of the genes in the genome of the serovar 5 <it>A. pleuropneumoniae </it>L20 strain were conserved in the reference strains of all 15 serovars and in representative field isolates. Fifty-eight conserved genes predicted to encode for outer membrane proteins or lipoproteins were identified. As well, there were several clusters of diverged or absent genes including those associated with capsule biosynthesis, toxin production as well as genes typically associated with mobile elements.</p> <p>Conclusion</p> <p>Although <it>A. pleuropneumoniae </it>strains are essentially clonal, M-CGH analysis of the reference strains of the fifteen serovars and representative field isolates revealed several classes of genes that were divergent or absent. Not surprisingly, these included genes associated with capsule biosynthesis as the capsule is associated with sero-specificity. Several of the conserved genes were identified as candidates for vaccine development, and we conclude that M-CGH is a valuable tool for reverse vaccinology.</p

Enhanced Binding of TonB to a Ligand-loaded Outer Membrane Receptor: ROLE OF THE OLIGOMERIC STATE OF TonB IN FORMATION OF A FUNCTIONAL FhuA·TonB COMPLEX

The ferric hydroxymate uptake (FhuA) receptor from Escherichia coli facilitates transport of siderophores ferricrocin and ferrichrome and siderophore-antibiotic conjugates such as albomycin and rifamycin CGP 4832. FhuA is also the receptor for phages T5, T1, 80, UC-1, for colicin M and for the antimicrobial peptide microcin MccJ21. Energy for transport is provided by the cytoplasmic membrane complex TonB·ExbB·ExbD, which uses the proton motive force of the cytoplasmic membrane to transduce energy to the outer membrane. To accomplish energy transfer, TonB contacts outer membrane receptors. However, the stoichiometry of TonB· receptor complexes and their sites of interaction remain uncertain. In this study, analyses of FhuA interactions with two recombinant TonB proteins by analytical ultracentrifugation revealed that TonB forms a 2:1 complex with FhuA. The presence of the FhuA-specific ligand ferricrocin enhanced the amounts of complex but is not essential for its formation. Surface plasmon resonance experiments demonstrated that FhuA·TonB interactions are multiple and have apparent affinities in the nanomolar range. TonB also possesses two distinct binding regions: one in the C terminus of the protein, for which binding to FhuA is ferricrocin-independent, and a higher affinity region outside the C terminus, for which ferricrocin enhances interactions with FhuA. Together these experiments establish that FhuA·TonB interactions are more intricate than originally predicted, that the TonB·FhuA stoichiometry is 2:1, and that ferricrocin modulates binding of FhuA to TonB at regions outside the C-terminal domain of TonB