4,459 research outputs found

    Comparative ecology of two South American foxes, Dusicyon griseus and D culpaeus

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    Culpeo (Dusicyon culpaeus) and South American grey fox (D. griseus) have comparable ranges, but the factors determining local and geographic distribution are unknown. I first review the best documented cases of sympatry in canids, and discuss the implications this analysis has on canid conservation. I then compare the behavioral ecology of grey and culpeo fox in Torres del Paine National Park, Chile and review hypothetical factors that determine their distribution when sympatric;The number of sympatric canids per area seems to be determined by a combination of biogeographical history, human intervention, and environmental diversity and productivity. Sympatric canid species either segregate in different habitats or utilize different food resources, but do not do both. Interactions among sympatric canid species may have important conservation and management implications because canid community structure often changes after a species\u27 range expansion, extirpation, or reintroduction;From 1986 through 1989, 44 grey and 19 culpeo fox were monitored using radio telemetry techniques. European hare (Lepus capensis) was the most common vertebrate found in grey fox feces (45%), followed by guanaco (Lama guanicoe, 14%) and Akodon species (13%). European hare accounted for 69% of the prey items and rodents 20% in culpeo fox feces. Yearly diets were significantly different. Grey fox were more omnivorous than culpeo fox. I suggest that differences in feeding habits were attributable to differences in food availability;Home ranges of culpeo fox were significantly larger than those of grey fox, but did not differ between sexes or among seasons. Home ranges of both species were interspersed but did not overlap. There were significant differences in fox use of habitat. Grey fox were located more in upland shrub transition habitat and in areas of medium habitat-density. Culpeo fox were found more in thickets of trees and in areas of high vegetative-density. Habitat use was related to availability. Interference competition by culpeo fox or exploitation competition may have been important in determining fox distribution. Based on fox energy requirements, it seems that the distribution of grey and culpeo fox in southern Chile is determined in part by the distribution and local density of European hare

    Development of a rural wine culture in Iowa

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    The project documents the process of creating a geographically-based identity for grapes and wine production in eastern Iowa

    A Mixed Methods Approach to Identifying Administration Issues Pertinent in Interscholastic Sports

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    The purpose of this study was to investigate three propositions: a) What are the administration issues most pertinent to interscholastic sport today, as well as the next five years?, b) How important are those administration issues to athletic administrators?, and c) What are the potential implications of those pertinent administration issues to practicing athletic administrators? The literature provides a general overview of relevant issues surrounding interscholastic athletics. However, the importance and implications of relevant issues to practicing high school athletic administrators are difficult to discern. To answer the first proposition, the Minnesota State High School League (MSHSL) provided 10 contemporary administration issues that were most pertinent to interscholastic sport today, as well as the next five years. To answer the second proposition, a Likert-Scale was created so that practicing athletic administrators could rate each issue on a scale of 5 = extremely important to 1 = very little importance. A national study was conducted with athletic directors from the National Interscholastic Athletic Administrators Association (N = 170) annual conference. A one-tailed ANOVA was executed to determine significant differences among the 10 administration issues identified by the MSHSL. Four issues were found to be significant; Athletic Facilities, Athletic Training, Health Issues and Travel Teams. A Games-Howell post hoc was executed to determine significant differences across geographical regions of the United States. For the third proposition, semi-structured interviews were completed to provide insight on the implications for practicing athletic administrators. The results offer insight from which further investigations could be conducted to continue building on policies that influence interscholastic athletic administrators’ day-to-day accountability when overseeing their athletic programs

    Resource Acquisition in the Presence of a Novel Stimulus by Coyotes of Different Social Rank

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    This study investigated the acquisition of food by hand-reared coyotes, Canis latrans, of different social rank in a familiar area with and without novel objects (safe and potentially unsafe conditions). The first objective was to test the hypothesis that dominant animals are more hesitant than subordinates in approaching food in the presence of a novel stimulus. The results were that dominant pups usually were the first to feed in the absence of novel stimulus, and subordinate pups were the first to feed when novel objects were present

    The Dynamic Proliferation of CanSINEs Mirrors the Complex Evolution of Feliforms

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    Background: Repetitive short interspersed elements (SINEs) are retrotransposons ubiquitous in mammalian genomes and are highly informative markers to identify species and phylogenetic associations. Of these, SINEs unique to the order Carnivora (CanSINEs) yield novel insights on genome evolution in domestic dogs and cats, but less is known about their role in related carnivores. In particular, genome-wide assessment of CanSINE evolution has yet to be completed across the Feliformia (cat-like) suborder of Carnivora. Within Feliformia, the cat family Felidae is composed of 37 species and numerous subspecies organized into eight monophyletic lineages that likely arose 10 million years ago. Using the Felidae family as a reference phylogeny, along with representative taxa from other families of Feliformia, the origin, proliferation and evolution of CanSINEs within the suborder were assessed. Results: We identified 93 novel intergenic CanSINE loci in Feliformia. Sequence analyses separated Feliform CanSINEs into two subfamilies, each characterized by distinct RNA polymerase binding motifs and phylogenetic associations. Subfamily I CanSINEs arose early within Feliformia but are no longer under active proliferation. Subfamily II loci are more recent, exclusive to Felidae and show evidence for adaptation to extant RNA polymerase activity. Further, presence/absence distributions of CanSINE loci are largely congruent with taxonomic expectations within Feliformia and the less resolved nodes in the Felidae reference phylogeny present equally ambiguous CanSINE data. SINEs are thought to be nearly impervious to excision from the genome. However, we observed a nearly complete excision of a CanSINEs locus in puma (Puma concolor). In addition, we found that CanSINE proliferation in Felidae frequently targeted existing CanSINE loci for insertion sites, resulting in tandem arrays. Conclusions: We demonstrate the existence of at least two SINE families within the Feliformia suborder, one of which is actively involved in insertional mutagenesis. We find SINEs are powerful markers of speciation and conclude that the few inconsistencies with expected patterns of speciation likely represent incomplete lineage sorting, species hybridization and SINE-mediated genome rearrangement

    Millisecond Pulsars: Detectable Sources of Continuous Gravitational Waves?

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    Laboratory searches for the detection of gravitational waves have focused on the detection of burst signals emitted during a supernova explosion, but have not resulted in any confirmed detections. An alternative approach has been to search for continuous wave (CW) gravitational radiation from the Crab pulsar. In this paper, we examine the possibility of detecting CW gravitational radiation from pulsars and show that nearby millisecond pulsars are generally much better candidates. We show that the minimum strain h_c ~ 10E-26 that can be detected by tuning an antenna to the frequency of the milli- second pulsar PSR 1957+20, with presently available detector technology, is orders of magnitude better than what has been accomplished so far by observing the Crab pulsar, and within an order of magnitude of the maximum strain that may be produced by it. In addition, we point out that there is likely to be a population of rapidly rotating neutron stars (not necessarily radio pulsars) in the solar neighborhood whose spindown evolution is driven by gravitational radiation. We argue that the projected sensitivity of modern resonant detectors is sufficient to detect the subset of this population that lies within 0.1 kpc of the sun.Comment: 17 pages (including 2 Postscript figures), LaTeX file, uses AASTeX macros, accepted for publication in the Astrophysical Journa

    The Role of Gene Duplication and Unconstrained Selective Pressures in the Melanopsin Gene Family Evolution and Vertebrate Circadian Rhythm Regulation

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    Melanopsin is a photosensitive cell protein involved in regulating circadian rhythms and other non-visual responses to light. The melanopsin gene family is represented by two paralogs,OPN4x and OPN4m, which originated through gene duplication early in the emergence of vertebrates. Here we studied the melanopsin gene family using an integrated gene/protein evolutionary approach, which revealed that the rhabdomeric urbilaterian ancestor had the same amino acid patterns (DRY motif and the Y and E conterions) as extant vertebrate species, suggesting that the mechanism for light detection and regulation is similar to rhabdomeric rhodopsins. Both OPN4m and OPN4x paralogs are found in vertebrate genomic paralogons, suggesting that they diverged following this duplication event about 600 million years ago, when the complex eye emerged in the vertebrate ancestor. Melanopsins generally evolved under negative selection (ω = 0.171) with some minor episodes of positive selection (proportion of sites = 25%) and functional divergence (θI = 0.349 and θII = 0.126). The OPN4m and OPN4x melanopsin paralogs show evidence of spectral divergence at sites likely involved in melanopsin light absorbance (200F, 273S and 276A). Also, following the teleost lineage-specific whole genome duplication (3R) that prompted the teleost fish radiation, type I divergence (θI = 0.181) and positive selection (affecting 11% of sites) contributed to amino acid variability that we related with the photo-activation stability of melanopsin. The melanopsin intracellular regions had unexpectedly high variability in their coupling specificity of G-proteins and we propose that Gq/11 and Gi/o are the two G-proteins most-likely to mediate the melanopsin phototransduction pathway. The selection signatures were mainly observed on retinal-related sites and the third and second intracellular loops, demonstrating the physiological plasticity of the melanopsin protein group. Our results provide new insights on the phototransduction process and additional tools for disentangling and understanding the links between melanopsin gene evolution and the specializations observed in vertebrates, especially in teleost fish

    Hearing and dementia: from ears to brain

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    The association between hearing impairment and dementia has emerged as a major public health challenge, with significant opportunities for earlier diagnosis, treatment and prevention. However, the nature of this association has not been defined. We hear with our brains, particularly within the complex soundscapes of everyday life: neurodegenerative pathologies target the auditory brain, and are therefore predicted to damage hearing function early and profoundly. Here we present evidence for this proposition, based on structural and functional features of auditory brain organization that confer vulnerability to neurodegeneration, the extensive, reciprocal interplay between ‘peripheral’ and ‘central’ hearing dysfunction, and recently characterized auditory signatures of canonical neurodegenerative dementias (Alzheimer’s disease, Lewy body disease and frontotemporal dementia). Moving beyond any simple dichotomy of ear and brain, we argue for a reappraisal of the role of auditory cognitive dysfunction and the critical coupling of brain to peripheral organs of hearing in the dementias. We call for a clinical assessment of real-world hearing in these diseases that moves beyond pure tone perception to the development of novel auditory ‘cognitive stress tests’ and proximity markers for the early diagnosis of dementia and management strategies that harness retained auditory plasticit

    Molecular evolution and the role of oxidative stress in the expansion and functional diversification of cytosolic glutathione transferases

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    <p>Abstract</p> <p>Background</p> <p>Cytosolic glutathione transferases (cGST) are a large group of ubiquitous enzymes involved in detoxification and are well known for their undesired side effects during chemotherapy. In this work we have performed thorough phylogenetic analyses to understand the various aspects of the evolution and functional diversification of cGSTs. Furthermore, we assessed plausible correlations between gene duplication and substrate specificity of gene paralogs in humans and selected species, notably in mammalian enzymes and their natural substrates.</p> <p>Results</p> <p>We present a molecular phylogeny of cytosolic GSTs that shows that several classes of cGSTs are more ubiquitous and thus have an older ancestry than previously thought. Furthermore, we found that positive selection is implicated in the diversification of cGSTs. The number of duplicate genes per class is generally higher for groups of enzymes that metabolize products of oxidative damage.</p> <p>Conclusions</p> <p>1) Protection against oxidative stress seems to be the major driver of positive selection in mammalian cGSTs, explaining the overall expansion pattern of this subfamily;</p> <p>2) Given the functional redundancy of GSTs that metabolize xenobiotic chemicals, we would expect the loss of gene duplicates, but by contrast we observed a gene expansion of this family, which likely has been favored by: i) the diversification of endogenous substrates; ii) differential tissue expression; and iii) increased specificity for a particular molecule;</p> <p>3) The increased availability of sequence data from diversified taxa is likely to continue to improve our understanding of the early origin of the different cGST classes.</p
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