Plant and habitat use by Black‐breasted Pufflegs (Eriocnemis nigrivestis), a critically endangered hummingbird

Black‐breasted Pufflegs (Eriocnemis nigrivestis) are hummingbirds endemic to Ecuador and are considered critically endangered because of their limited distribution, a population estimated at fewer than 1000 individuals, and ongoing habitat degradation. From November 2013 to June 2016, we examined the foraging preferences of these hummingbirds using a combination of direct observations, time‐lapse cameras, and motion‐detection software. We first identified 21 species of ornithophilous plants distributed among five sites in the northwestern flanks of the Pichincha volcano in northwest Ecuador. We then monitored these plant species using time‐lapse cameras and recorded 144 visits by Black‐breasted Pufflegs to seven of the 21 species. Most visits (128 of 144 visits, 89%) were to just two species of plants, Macleania rupestris and Palicourea fuchsioides, the latter of which is also an endemic and threatened species. In addition, Black‐breasted Pufflegs were only observed in the most pristine habitats. Given the potential negative effects of climate change for species in the tropical Andes plus the possible loss and degradation of habitat resulting from human activities, efforts are needed to conserve habitats currently used by Black‐breasted Pufflegs, recover degraded habitats, and connect isolated patches of suitable habitat. Our results concerning species of flowering plants used most by Black‐breasted Pufflegs (P. fuchsioides and M. rupestris) should help guide any habitat restoration initiatives.     

Towards a biomechanics-based technique for assessing myocardial contractility: an inverse problem approach

This work presents the initial development and implementation of a novel 3D biomechanics-based approach to measure the mechanical activity of myocardial tissue, as a potential non-invasive tool to assess myocardial function. This technique quantifies the myocardial contraction forces developed within the ventricular myofibers in response to electro-physiological stimuli. We provide a 3D finite element formulation of a contraction force reconstruction algorithm, along with its implementation using magnetic resonance (MR) data. Our algorithm is based on an inverse problem solution governed by the fundamental continuum mechanics principle of conservation of linear momentum, under a first-order approximation of elastic and isotropic material conditions. We implemented our technique using a subject-specific ventricle model obtained by extracting the left ventricular anatomical features from a set of high-resolution cardiac MR images acquired throughout the cardiac cycle using prospective electrocardiographic gating. Cardiac motion information was extracted by non-rigid registration of the mid-diastole reference image to the remaining images of a 4D dataset. Using our technique, we reconstructed dynamic maps that show the contraction force distribution superimposed onto the deformed ventricle model at each acquired frame in the cardiac cycle. Our next objective will consist of validating this technique by showing the correlation between the presence of low contraction force patterns and poor myocardial functionality.     

Ecological implications of extreme events: footprints of the 2010 earthquake along the Chilean coast

Deciphering ecological effects of major catastrophic events such as earthquakes, tsunamis, volcanic eruptions, storms and fires, requires rapid interdisciplinary efforts often hampered by a lack of pre-event data. Using results of intertidal surveys conducted shortly before and immediately after Chile's 2010 M(w) 8.8 earthquake along the entire rupture zone (ca. 34-38°S), we provide the first quantification of earthquake and tsunami effects on sandy beach ecosystems. Our study incorporated anthropogenic coastal development as a key design factor. Ecological responses of beach ecosystems were strongly affected by the magnitude of land-level change. Subsidence along the northern rupture segment combined with tsunami-associated disturbance and drowned beaches. In contrast, along the co-seismically uplifted southern rupture, beaches widened and flattened increasing habitat availability. Post-event changes in abundance and distribution of mobile intertidal invertebrates were not uniform, varying with land-level change, tsunami height and coastal development. On beaches where subsidence occurred, intertidal zones and their associated species disappeared. On some beaches, uplift of rocky sub-tidal substrate eliminated low intertidal sand beach habitat for ecologically important species. On others, unexpected interactions of uplift with man-made coastal armouring included restoration of upper and mid-intertidal habitat seaward of armouring followed by rapid colonization of mobile crustaceans typical of these zones formerly excluded by constraints imposed by the armouring structures. Responses of coastal ecosystems to major earthquakes appear to vary strongly with land-level change, the mobility of the biota and shore type. Our results show that interactions of extreme events with human-altered shorelines can produce surprising ecological outcomes, and suggest these complex responses to landscape alteration can leave lasting footprints in coastal ecosystems.     

Horizontal gene transfer of a ColV plasmid has resulted in a dominant avian clonal type of Salmonella enterica serovar Kentucky

Salmonella enterica continues to be a significant cause of foodborne gastrointestinal illness in humans. A wide variety of Salmonella serovars have been isolated from production birds and from retail poultry meat. Recently, though, S. enterica subsp. enterica serovar Kentucky has emerged as one of the prominent Salmonella serovars isolated from broiler chickens. Recent work suggests that its emergence apparently coincides with its acquisition of a ColV virulence plasmid. In the present study, we examined 902 Salmonella isolates belonging to 59 different serovars for the presence of this plasmid. Of the serovars examined, the ColV plasmid was found only among isolates belonging to the serovars Kentucky (72.9%), Typhimurium (15.0%) and Heidelberg (1.7%). We demonstrated that a single PFGE clonal type of S. Kentucky harbors this plasmid, and acquisition of this plasmid by S. Kentucky significantly increased its ability to colonize the chicken cecum and cause extraintestinal disease. Comparison of the completed sequences of three ColV plasmids from S. Kentucky isolated from different geographical locales, timepoints and sources revealed a nearly identical genetic structure with few single nucleotide changes or insertions/deletions. Overall, it appears that the ColV plasmid was recently acquired by a single clonal type S. Kentucky and confers to its host enhanced colonization and fitness capabilities. Thus, the potential for horizontal gene transfer of virulence and fitness factors to Salmonella from other enteric bacteria exists in poultry, representing a potential human health hazard.     

A general model for amyloid fibril assembly based on morphological studies using atomic force microscopy

Based on atomic force microscopy analysis of the morphology of fibrillar species formed during fibrillation of alpha-synuclein, insulin, and the B1 domain of protein G, a previously described model for the assembly of amyloid fibrils of immunoglobulin light-chain variable domains is proposed as a general model for the assembly of protein fibrils. For all of the proteins studied, we observed two or three fibrillar species that vary in diameter. The smallest, protofilaments, have a uniform height, whereas the larger species, protofibrils and fibrils, have morphologies that are indicative of multiple protofilaments intertwining. In all cases, protofilaments intertwine to form protofibrils, and protofibrils intertwine to form fibrils. We propose that the hierarchical assembly model describes a general mechanism of assembly for all amyloid fibrils.     

Enhanced Wound Healing Activity of Undenatured Type I Collagen Isolated from Discarded Skin of Black Sea Gilthead Bream (Sparus aurata) Conditioned as 3D Porous Dressing

Acid-soluble, undenatured, type I collagen (BSC) isolated, for the first time, from gilthead bream skin and the novel fabricated 3D porous wound dressing were analyzed for physicochemical and biological properties, in order to offer a safe alternative to commercial bovine collagen (BC) products. SDS-polyacrylamide analysis confirmed the purity of BSC preparation. The hydroxyproline content and temperature of denaturation of BSC were lower than those of BC, in accordance with the structural data recorded by FT-IR spectroscopy. However, certain concentrations of BSC stimulated the cell metabolism of L929 fibroblasts in a higher proportion than BC. The 3D wound dressing presented high porosity and low surface hydrophobicity that could help cell attachment and growth. The rapid biodegradation of BSC wound dressing could explain the improved in vitro cell migration and wound closure rate. In conclusion, the skin of gilthead bream from the Black Sea coast represented a valuable source for the biomedical industry, providing biocompatible, biodegradable collagen and 3D porous wound dressing, as novel material with enhanced wound healing activity.     

Drought Impacts Survivorship and Reproductive Strategies of an Epiphyllous Leafy Liverwort in Central Amazonia

Understanding how changing precipitation patterns impact the population dynamics of Amazonian plants is necessary for predicting their long‐term survival. Most terrestrial plants are characterized by life cycles intractably slow for evaluating such demographic consequences. Due to the demands of surviving on an ephemeral substrate such as a leaf surface, epiphyllous (leaf‐inhabiting) bryophytes have some of the fastest generation times for terrestrial plants. Considering these advantages, we investigated the demographic consequences of seasonality in precipitation during one‐year of the epiphyllous bryophyte Radula flaccida Gott. (Radulaceae) in a central Amazonian rain forest. In a 1‐ha sized study area, 154 epiphyll colonies from 18 phorophytes of the understory shrub Naucleopsis ulei (Warb.) Ducke (Moraceae) were marked and colony growth, extinction, recolonization, as well as rates of sexual and asexual expression were measured in nine demographic censuses. The probability of survivorship decreased in the dry season due to the synergistic effects of both increased leaf fall (e.g., loss of occupied patches) and colony mortality on persisting leaves. Asexual expression also declined significantly during the driest months; however, sexual expression, as measured by sporophyte density, was not related to seasonality. Logistic regression probabilities also indicate a minimum threshold colony size for optimal sporophyte expression. Lower survivorship and colony growth in the dry season along with reduced sporophyte production in smaller colonies implies that both demographic stability as well as population structure of Amazonian epiphyll species may be compromised whether climate models projecting prolonged droughts for the region are accurate.