Behavioral and histological inflammatory analysis of a single, mild traumatic brain injury and repeated subconcussive brain injury using a rodent model.

Subconcussive (SC) impacts have become a growing concern within the neuroscience community regarding the immediate and long-lasting effects of sports-related injuries. While a single low-level impact, i.e., a subconcussion, may not cause cerebral perturbations, it has been increasingly recognized that repeated SC exposure can induce deleterious effects. Therefore, determining the lower limits of systematic perturbation resulting from multiple SC impacts is of critical importance in expanding our understanding of cerebral vulnerability and recovery. Currently, there is a lack of correlation between a mild traumatic brain injury (mTBI) and repeated SC impacts with respect to injury biomechanics. Moreover, the cumulative threshold for repetitive low-level impacts is currently undefined. Thus, this research was designed to determine the pathophysiological differences between a single impact of an mTBI and repeated SC impacts with a subdivided cumulative kinetic energy of the single mTBI impact. In order to address this gap in knowledge, the present investigation employed a surgery-free, closed-head, weight drop injury device capable of producing repeatable, head impacts within a rat model. General locomotion and anxiety-like behavior were assessed using an Open Field Test and motor coordination dysfunction was measured using the rotarod assay. Neuroinflammation was measured using immunohistochemical assessment of astrogliosis (GFAP) and microgliosis (Iba-1) within the hippocampus. Additionally, immunohistochemical assessment of neuronal loss (NeuN) was measured within the hippocampus. To investigate the tolerance and the persistence of cerebral vulnerability following a single mTBI and repeated subconcussive impacts, measurement outcomes were assessed over two-time points (3- and 7-days) post final impact. Although injury groups were not statistically different from their associated sham groups with respect to behavioral outcomes; on average, RSC injury rats displayed a significant increase in anxious-like behavior after 7-days of recovery compared to the single mTBI group. From an inflammatory perspective, both mTBI and RSC injury groups led to extensive microgliosis in the gray matter following 3-days post-impact. Overall, this work’s findings do not provide evidence in support of the notion that repeated subconcussive impacts do result in behavioral disturbances and neuroinflammation, that do not manifest following a single mTBI of the same energy input

Response of Grassland Birds to Agricultural Intensity at Different Spatial Scales in Texas

The decline in grassland birds is often associated with habitat loss due to intensity of conversion to agricultural lands and the alterations of natural disturbances. We sought to identify agricultural effects at differing scales that correlate to Texas grassland bird abundance, especially northern bobwhite (Colinus virginianus). Ninety-five roadside routes were surveyed in 20 Texas counties ranging from the Oklahoma border to the coastal plains. We conducted point counts in May and June from 2013 to 2016. To estimate the coarse effects of agriculture on bird abundance at a county level, we used number of cattle and area of farmland used per crop type amongst other data from the National Agriculture Statistics Service (NASS, 2012) for analyses. For estimates at finer scales, including the scale of individual routes and points, we obtained annual agricultural data and GIS layers from the NASS. We determined the predictive ability of each agricultural type via linear models and stepwise selection. From 2013 to 2016, we detected 32,373 individual birds, including 5,329 northern bobwhite, from 150,423 point count surveys. Our preliminary results revealed that agriculture only affects a few species at a county level. The top models for rufous-crowned sparrows (Aimophila ruficeps) and field sparrows (Spizella pusilla) included only one predictor from the full model - the number of cattle per county (R2 = 0.10; R2 = 0.29). The top model for yellow-billed cuckoos (Coccyzus americanus) included cattle per county and year, while the best model was found for dickcissels (Spiza americana), which included year and the proportions of woodland agriculture and pasture (R2 = 0.23; R2 = 0.33). While our results may indicate that agriculture impacts some species on coarse scales, it appears that bobwhite are likely impacted only on smaller scales and further analysis will be needed to identify specific impacts of agriculture on these scales

Synergism and context dependency of interactions between arbuscular mycorrhizal fungi and rhizobia with prairie legume

Biotic interactions play primary roles in major theories of the distribution and abundance of species, yet the nature of these biotic interactions can depend upon the larger ecological community. Leguminous plants, for example, commonly associate with both arbuscular mycorrhizal fungi (AMF) and rhizobia bacteria, and the pairwise interactions may depend upon the presence or identity of the third partner. To determine if the dynamics of plant–AMF and plant–rhizobia interactions are affected by the alternate symbiont, we manipulated the presence and identity of each symbiont, as well as levels of the nutrients supplied by each symbiont (nitrogen and phosphorus), on the growth of prairie legume Amorpha canescens. We found strong synergistic effects of AMF and rhizobia inoculation on plant biomass production that were independent of nutrient levels. AMF and rhizobia responses were each influenced by the other, but not in the same direction. AMF infection increased root nodule number and mass, but rhizobia inoculation decreased AMF hyphal colonization of roots. The relative benefits of each combination of symbionts depended upon phosphorus level. The effect of nitrogen was also contingent on the biotic environment where nitrogen addition decreased nodulation, but this decrease was reduced with coinfection by AMF. Our results demonstrate a strong contingency on the co-occurrence of AMF and rhizobia for the long-term fitness of A. canescens, and suggest that the belowground community is critical for the success of this species in tallgrass prairies

Fish Assemblages of the Upper Little Sioux River Basin, Iowa, USA: Relationships with Stream Size and Comparison with Historical Assemblages

We characterized the fish assemblages in second to fifth order streams of the upper Little Sioux River basin in northwest Iowa, USA and compared our results with historical surveys. The fish assemblage consisted of over twenty species, was dominated numerically by creek chub, sand shiner, central stoneroller and other cyprinids, and was dominated in biomass by common carp. Most of the species and the great majority of all individuals present were at least moderately tolerant to environmental degradation, and biotic integrity at most sites was characterized as fair. Biotic integrity declined with increasing stream size, and degraded habitat in larger streams is a possible cause. No significant changes in species richness or the relative distribution of species\u27 tolerance appear to have occurred since the 1930s

Characteristics and Risk of Microgrid Outages from a Complex Systems Point of View

Cordova is a town of approximately 2,000 people located on the southern coast of Alaska. A power grid for a town this size, with a large seasonal fishing economy, is considered a moderate to large sized microgrid in terms of power produced. Understanding the vulnerabilities and risks of failures in such a grid is important for planning and operations. Investigating these characteristics in the context of complex system dynamics is a novel approach. The analysis of Cordova’s microgrid is a case study relevant to a large class of microgrid communities. We analyze the outage data based on size, cause characteristics and load demand on the system and find long time correlations and power laws in the failure size distributions. Finally we apply a risk metric to give a single numerical value to the risk of an outage occurring during certain time periods and under certain conditions

Contributions of Spore Secondary Metabolites to UV-C Protection and Virulence Vary in Different Aspergillus fumigatus Strains

Fungi are versatile organisms which thrive in hostile environments, including the International Space Station (ISS). Several isolates of the human pathogen Aspergillus fumigatus have been found contaminating the ISS, an environment with increased exposure to UV radiation. Secondary metabolites (SMs) in spores, such as melanins, have been shown to protect spores from UV radiation in other fungi. To test the hypothesis that melanin and other known spore SMs provide UV protection to A. fumigatus isolates, we subjected SM spore mutants to UV-C radiation. We found that 1,8-dihydroxynaphthalene (DHN)-melanin mutants of two clinical A. fumigatus strains (Af293 and CEA17) but not an ISS-isolated strain (IF1SW-F4) were more sensitive to UV-C than their respective wild-type (WT) strains. Because DHN-melanin has been shown to shield A. fumigatus from the host immune system, we examined all DHN mutants for virulence in the zebrafish model of invasive aspergillosis. Following recent studies highlighting the pathogenic variability of different A. fumigatus isolates, we found DHN-melanin to be a virulence factor in CEA17 and IF1SW-F4 but not Af293. Three additional spore metabolites were examined in Af293, where fumiquinazoline also showed UV-C-protective properties, but two other spore metabolites, monomethylsulochrin and fumigaclavine, provided no UV-C-protective properties. Virulence tests of these three SM spore mutants indicated a slight increase in virulence of the monomethylsulochrin deletion strain. Taken together, this work suggests differential roles of specific spore metabolites across Aspergillus isolates and by types of environmental stress

Anticipating and Managing Future Trade-offs and Complementarities between Ecosystem Services

This paper shows how, with the aid of computer models developed in close collaboration with decision makers and other stakeholders, it is possible to quantify and map how policy decisions are likely to affect multiple ecosystem services in future. In this way, potential trade-offs and complementarities between different ecosystem services can be identified, so that policies can be designed to avoid the worst trade-offs, and where possible, enhance multiple services. The paper brings together evidence from across the Rural Economy and Land Use Programme’s Sustainable Uplands project for the first time, with previously unpublished model outputs relating to runoff, agricultural suitability, biomass, heather cover, age, and utility for Red Grouse (Lagopus scotica), grass cover, and accompanying scenario narratives and video. Two contrasting scenarios, based on policies to extensify or intensify land management up to 2030, were developed through a combination of interviews and discussions during site visits with stakeholders, literature review, conceptual modeling, and process-based computer models, using the Dark Peak of the Peak District National Park in the UK as a case study. Where extensification leads to a significant reduction in managed burning and grazing or land abandonment, changes in vegetation type and structure could compromise a range of species that are important for conservation, while compromising provisioning services, amenity value, and increasing wildfire risk. However, where extensification leads to the restoration of peatlands damaged by former intensive management, there would be an increase in carbon sequestration and storage, with a number of cobenefits, which could counter the loss of habitats and species elsewhere in the landscape. In the second scenario, land use and management was significantly intensified to boost UK self-sufficiency in food. This would benefit certain provisioning services but would have negative consequences for carbon storage and water quality and would lead to a reduction in the abundance of certain species of conservation concern. The paper emphasizes the need for spatially explicit models that can track how ecosystem services might change over time, in response to policy or environmental drivers, and in response to the changing demands and preferences of society, which are far harder to anticipate. By developing such models in close collaboration with decision makers and other stakeholders, it is possible to depict scenarios of real concern to those who need to use the research findings. By engaging these collaborators with the research findings through film, it was possible to discuss adaptive options to minimize trade-offs and enhance the provision of multiple ecosystem services under the very different future conditions depicted by each scenario. By preparing for as wide a range of futures as possible in this way, it may be possible for decision makers to act rapidly and effectively to protect and enhance the provision of ecosystem services in the face of unpredictable future change.Additional co-authors: Nanlin Jin, Brian J Irvine, Mike J Kirkby, William E Kunin, Christina Prell, Claire H Quinn, Bill Slee, Sigrid Stagl, Mette Termansen, Simon Thorp, and Fred Worral