413 research outputs found

    Red-Cockaded Woodpecker Recovery: An Integrated Strategy

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    Populations of the red-cockaded woodpecker (Picoides borealis) have experienced massive declines since European colonization of North America. This is due to extensive habitat loss and alteration. Logging of old-growth pine forests and alteration of the fire regime throughout the historic range of the species were the primary causes of population decline. Listing of the red-cockaded woodpecker under the Endangered Species Act of 1973, as amended, and increased emphasis on management of non-game species have resulted in efforts to recover remnant populations of the red-cockaded woodpecker in many parts of its historic range. Due to extensive research and adaptive management initiatives much is now known about the elements required for both short- and long-term management of viable populations of red-cockaded woodpeckers. A short-term strategy is crucial because currently available habitat, in nearly all populations, is poor in 1 or more critical respects. Consequently, almost all populations require immediate attention in the short term, to insure suitable midstory and understory conditions, adequate availability of suitable cavities, and restoration of demographic viability through improvements in number and distribution of breeding groups. Management techniques including artificial cavities, cavity entrance restrictors, translocation of birds, prescribed fire, and mechanical and chemical control of woody vegetation are available to achieve these needs. In the long term, cost-effective management of red-cockaded woodpecker populations requires a timber management program and prescribed fire regime that will produce and maintain the stand structure characteristic of high quality nesting and foraging habitat, so that additional intensive management specific to the woodpeckers is no longer necessary. Timber management that achieves this goal and still allows substantial timber harvest is feasible. The implementation of a red-cockaded woodpecker management strategy, as outlined above, represents appropriate ecosystem management in the fire-maintained pine ecosystems of the southeastern United States and will ultimately benefit a great number of additional species of plants and animals adapted to this ecosystem

    A generalizable scaffold-based approach for structure determination of RNAs by cryo-EM.

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    Single-particle cryo-electron microscopy (cryo-EM) can reveal the structures of large and often dynamic molecules, but smaller biomolecules (≤50 kDa) remain challenging targets due to their intrinsic low signal to noise ratio. Methods to help resolve small proteins have been applied but development of similar approaches to aid in structural determination of small, structured RNA elements have lagged. Here, we present a scaffold-based approach that we used to recover maps of sub-25 kDa RNA domains to 4.5-5.0 Å. While lacking the detail of true high-resolution maps, these maps are suitable for model building and preliminary structure determination. We demonstrate this method helped faithfully recover the structure of several RNA elements of known structure, and that it promises to be generalized to other RNAs without disturbing their native fold. This approach may streamline the sample preparation process and reduce the optimization required for data collection. This first-generation scaffold approach provides a robust system to aid in RNA structure determination by cryo-EM and lays the groundwork for further scaffold optimization to achieve higher resolution

    Red-Cockaded Woodpecker Status and Management: West Gulf Coastal Plain and Interior Highlands

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    Red-cockaded woodpecker populations declined precipitously following European settlement and expansion and cutting of the original pine forests across the southeastern United States. By 1990 most residual populations lacked demographic viability, existed in degraded habitat, and were isolated from other populations. The primary causes of this situation were harvest of the original pine forests of the southeastern United States, conversion of forested lands to other uses, short-rotation silvicultural practices, and alteration of the fire regime in the regenerated forests. As social and legal mandates changed, management of red-cockaded woodpeckers became a higher priority. Intensive management for red-cockaded woodpeckers is currently practiced on most public and a few private lands that still support populations. Recent population trends and the current status of red-cockaded woodpeckers in Oklahoma, Arkansas, Texas, and Louisiana reflect historical factors and the efficacy of recent management

    An expanded class of histidine-accepting viral tRNA-like structures.

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    Structured RNA elements are common in the genomes of RNA viruses, often playing critical roles during viral infection. Some viral RNA elements use forms of tRNA mimicry, but the diverse ways this mimicry can be achieved are poorly understood. Histidine-accepting tRNA-like structures (TLSHis) are examples found at the 3 termini of some positive-sense single-stranded RNA (+ssRNA) viruses where they interact with several host proteins, induce histidylation of the RNA genome, and facilitate processes important for infection, to include genome replication. As only five TLSHis examples had been reported, we explored the possible larger phylogenetic distribution and diversity of this TLS class using bioinformatic approaches. We identified many new examples of TLSHis, yielding a rigorous consensus sequence and secondary structure model that we validated by chemical probing of representative TLSHis RNAs. We confirmed new examples as authentic TLSHis by demonstrating their ability to be histidylated in vitro, then used mutational analyses to imply a tertiary interaction that is likely analogous to the D- and T-loop interaction found in canonical tRNAs. These results expand our understanding of how diverse RNA sequences achieve tRNA-like structure and function in the context of viral RNA genomes and lay the groundwork for high-resolution structural studies of tRNA mimicry by histidine-accepting TLSs

    Getting Back to Nature: Feralization in Animals and Plants

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    Formerly domesticated organisms and artificially selected genes often escape controlled cultivation, but their subsequent evolution is not well studied. In this review, we examine plant and animal feralization through an evolutionary lens, including how natural selection, artificial selection, and gene flow shape feral genomes, traits, and fitness. Available evidence shows that feralization is not a mere reversal of domestication. Instead, it is shaped by the varied and complex histories of feral populations, and by novel selection pressures. To stimulate further insight we outline several future directions. These include testing how ‘domestication genes’ act in wild settings, studying the brains and behaviors of feral animals, and comparative analyses of feral populations and taxa. This work offers feasible and exciting research opportunities with both theoretical and practical applications

    Informal Science Engagement via Extension Exhibits: A Pilot Evaluation of Adult State Fairgoers’ Experiences, Attitudes, and Learning at Raising Nebraska

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    Science communication and informal science education collide in the context of Extension state fair exhibits for engaging public audiences in critical agricultural and natural resource issues impacting people’s daily lives. A need exists to employ systematic communication and education theory and techniques to effectively deliver scientific information in informal learning spaces. In an effort to apply and expand systematic instructional design thinking and research in informal science learning, this study piloted a touchscreen iPad survey evaluation (n= 93; ages 19-66) of adult state fairgoers’ demographics, experiences, attitudes, and learning during their visit to a 25,000 square-foot facility featuring an Extension museum-quality exhibit at the Nebraska State Fair in 2016. The exhibit included content such as farmers’ and ranchers’ stories, food security, soil quality, and water flow via natural landscapes and irrigation. Survey results included fairgoers’ demographics and backgrounds, as well as insights into favorite exhibit features, attitudes toward agricultural and environmental issues, and exhibit experience and attitude differences between visitors with agricultural backgrounds versus non-agricultural backgrounds. Results showed respondents were predominantly Caucasian with ties to agriculture, preferred physical and electronic engagement pieces of the exhibit compared to static text panels, and expressed slight changes in attitudes about agriculture with larger shifts in attitudes about the role of science in agriculture. Recommendations include systematically developing Extension informal learning efforts and exhibits such as the one in this study by conducting needs assessments and evaluations, as well as expanding exhibit locations, access, and topics to reach more diverse demographics

    Assessment of risk of insect-resistant transgenic crops to nontarget arthropods

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    An international initiative is developing a scientifically rigorous approach to evaluate the potential risks to nontarget arthropods (NTAs) posed by insect-resistant, genetically modified (IRGM) crops. It adapts the tiered approach to risk assessment that is used internationally within regulatory toxicology and environmental sciences. The approach focuses on the formulation and testing of clearly stated risk hypotheses, making maximum use of available data and using formal decision guidelines to progress between testing stages (or tiers). It is intended to provide guidance to regulatory agencies that are currently developing their own NTA risk assessment guidelines for IRGM crops and to help harmonize regulatory requirements between different countries and different regions of the world
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