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  1. Article ; Online: Avian binocular vision

    Luke P Tyrrell / Esteban Fernández-Juricic

    PLoS ONE, Vol 12, Iss 3, p e

    It's not just about what birds can see, it's also about what they can't.

    2017  Volume 0173235

    Abstract: With the exception of primates, most vertebrates have laterally placed eyes. Binocular vision in vertebrates has been implicated in several functions, including depth perception, contrast discrimination, etc. However, the blind area in front of the head ... ...

    Abstract With the exception of primates, most vertebrates have laterally placed eyes. Binocular vision in vertebrates has been implicated in several functions, including depth perception, contrast discrimination, etc. However, the blind area in front of the head that is proximal to the binocular visual field is often neglected. This anterior blind area is important when discussing the evolution of binocular vision because its relative length is inversely correlated with the width of the binocular field. Therefore, species with wider binocular fields also have shorter anterior blind areas and objects along the mid-sagittal plane can be imaged at closer distances. Additionally, the anterior blind area is of functional significance for birds because the beak falls within this blind area. We tested for the first time some specific predictions about the functional role of the anterior blind area in birds controlling for phylogenetic effects. We used published data on visual field configuration in 40 species of birds and measured beak and skull parameters from museum specimens. We found that birds with proportionally longer beaks have longer anterior blind areas and thus narrower binocular fields. This result suggests that the anterior blind area and beak visibility do play a role in shaping binocular fields, and that binocular field width is not solely determined by the need for stereoscopic vision. In visually guided foragers, the ability to see the beak-and how much of the beak can be seen-varies predictably with foraging habits. For example, fish- and insect-eating specialists can see more of their own beak than birds eating immobile food can. But in non-visually guided foragers, there is no consistent relationship between the beak and anterior blind area. We discuss different strategies-wide binocular fields, large eye movements, and long beaks-that minimize the potential negative effects of the anterior blind area. Overall, we argue that there is more to avian binocularity than meets the eye.
    Keywords Medicine ; R ; Science ; Q
    Subject code 590
    Language English
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: A novel cellular structure in the retina of insectivorous birds

    Luke P. Tyrrell / Leandro B. C. Teixeira / Richard R. Dubielzig / Diana Pita / Patrice Baumhardt / Bret A. Moore / Esteban Fernández-Juricic

    Scientific Reports, Vol 9, Iss 1, Pp 1-

    2019  Volume 10

    Abstract: Abstract The keen visual systems of birds have been relatively well-studied. The foundations of avian vision rest on their cone and rod photoreceptors. Most birds use four cone photoreceptor types for color vision, a fifth cone for achromatic tasks, and ... ...

    Abstract Abstract The keen visual systems of birds have been relatively well-studied. The foundations of avian vision rest on their cone and rod photoreceptors. Most birds use four cone photoreceptor types for color vision, a fifth cone for achromatic tasks, and a rod for dim-light vision. The cones, along with their oil droplets, and rods are conserved across birds – with the exception of a few shifts in spectral sensitivity – despite taxonomic, behavioral and ecological differences. Here, however, we describe a novel photoreceptor organelle in a group of New World flycatchers (Empidonax spp.) in which the traditional oil droplet is replaced with a complex of electron-dense megamitochondria surrounded by hundreds of small, orange oil droplets. The photoreceptors with this organelle were unevenly distributed across the retina, being present in the central region (including in the fovea), but absent from the retinal periphery and the area temporalis of these insectivorous birds. Of the many bird species with their photoreceptors characterized, only the two flycatchers described here (E. virescens and E. minimus) possess this unusual retinal structure. We discuss the potential functional significance of this unique sub-cellular structure, which might provide an additional visual channel for these small predatory songbirds.
    Keywords Medicine ; R ; Science ; Q
    Subject code 590
    Language English
    Publishing date 2019-10-01T00:00:00Z
    Publisher Nature Publishing Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: The Ethics of Reintroducing Large Carnivores

    A Lee / A M Laird / L Brann / C Coxon / A J Hamilton / L A Lawhon / J A Martin / N Rehnberg / B P Tyrrell / Z Welch / B Hale / P S Alagona

    Conservation & Society, Vol 19, Iss 1, Pp 80-

    The Case of the California Grizzly

    2021  Volume 90

    Abstract: Efforts to reintroduce species to portions of their historic ranges are growing in number and kind. These include proposals and projects to reintroduce large carnivores in areas where these species have been absent for decades. Reintroductions, like all ... ...

    Abstract Efforts to reintroduce species to portions of their historic ranges are growing in number and kind. These include proposals and projects to reintroduce large carnivores in areas where these species have been absent for decades. Reintroductions, like all conservation efforts, involve not only empirical and logistical problems, but also complex normative questions. So, what are the obligations, values, permissions, restrictions, and demands that citizens, conservationists, wildlife managers, and other impacted parties must address? This paper attempts to organise, summarise and briefly analyse the diverse suite of common normative arguments concerning large carnivore reintroduction. Clarifying arguments as a methodological approach grounded in environmental ethics sheds light on many implicit ethical presuppositions that underwrite reintroduction efforts. As an example, we use the grizzly bear (Ursus arctos), whose populations have grown in recent years in both Europe and North America. Whereas past efforts to recover grizzlies in the lower 48 U.S. states focused on the Northern Rockies and North Cascades, research, legal proceedings, and other proposals have emerged to return the species to other portions of its historic range, including California. Clarifying ethical arguments that may arise from large carnivore reintroduction can contribute to a more civil public discourse and effective decision-making processes.
    Keywords environmental ethics ; california ; grizzly bears ; large carnivore reintroduction ; restoration ethics ; Ecology ; QH540-549.5
    Subject code 170
    Language English
    Publishing date 2021-01-01T00:00:00Z
    Publisher Wolters Kluwer Medknow Publications
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: FOVEA

    Bret A. Moore / Innfarn Yoo / Luke P. Tyrrell / Bedrich Benes / Esteban Fernandez-Juricic

    PeerJ, Vol 4, p e

    a new program to standardize the measurement of foveal pit morphology

    2016  Volume 1785

    Abstract: The fovea is one of the most studied retinal specializations in vertebrates, which consists of an invagination of the retinal tissue with high packing of cone photoreceptors, leading to high visual resolution. Between species, foveae differ ... ...

    Abstract The fovea is one of the most studied retinal specializations in vertebrates, which consists of an invagination of the retinal tissue with high packing of cone photoreceptors, leading to high visual resolution. Between species, foveae differ morphologically in the depth and width of the foveal pit and the steepness of the foveal walls, which could influence visual perception. However, there is no standardized methodology to measure the contour of the foveal pit across species. We present here FOVEA, a program for the quantification of foveal parameters (width, depth, slope of foveal pit) using images from histological cross-sections or optical coherence tomography (OCT). FOVEA is based on a new algorithm to detect the inner retina contour based on the color variation of the image. We evaluated FOVEA by comparing the fovea morphology of two Passerine birds based on histological cross-sections and its performance with data from previously published OCT images. FOVEA detected differences between species and its output was not significantly different from previous estimates using OCT software. FOVEA can be used for comparative studies to better understand the evolution of the fovea morphology in vertebrates as well as for diagnostic purposes in veterinary pathology. FOVEA is freely available for academic use and can be downloaded at: http://estebanfj.bio.purdue.edu/fovea.
    Keywords Fovea ; Retina ; Foveal pit ; Comparative studies ; Medicine ; R ; Biology (General) ; QH301-705.5
    Subject code 590
    Language English
    Publishing date 2016-04-01T00:00:00Z
    Publisher PeerJ Inc.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Vision in two cyprinid fish

    Diana Pita / Bret A. Moore / Luke P. Tyrrell / Esteban Fernández-Juricic

    PeerJ, Vol 3, p e

    implications for collective behavior

    2015  Volume 1113

    Abstract: Many species of fish rely on their visual systems to interact with conspecifics and these interactions can lead to collective behavior. Individual-based models have been used to predict collective interactions; however, these models generally make ... ...

    Abstract Many species of fish rely on their visual systems to interact with conspecifics and these interactions can lead to collective behavior. Individual-based models have been used to predict collective interactions; however, these models generally make simplistic assumptions about the sensory systems that are applied without proper empirical testing to different species. This could limit our ability to predict (and test empirically) collective behavior in species with very different sensory requirements. In this study, we characterized components of the visual system in two species of cyprinid fish known to engage in visually dependent collective interactions (zebrafish Danio rerio and golden shiner Notemigonus crysoleucas) and derived quantitative predictions about the positioning of individuals within schools. We found that both species had relatively narrow binocular and blind fields and wide visual coverage. However, golden shiners had more visual coverage in the vertical plane (binocular field extending behind the head) and higher visual acuity than zebrafish. The centers of acute vision (areae) of both species projected in the fronto-dorsal region of the visual field, but those of the zebrafish projected more dorsally than those of the golden shiner. Based on this visual sensory information, we predicted that: (a) predator detection time could be increased by >1,000% in zebrafish and >100% in golden shiners with an increase in nearest neighbor distance, (b) zebrafish schools would have a higher roughness value (surface area/volume ratio) than those of golden shiners, (c) and that nearest neighbor distance would vary from 8 to 20 cm to visually resolve conspecific striping patterns in both species. Overall, considering between-species differences in the sensory system of species exhibiting collective behavior could change the predictions about the positioning of individuals in the group as well as the shape of the school, which can have implications for group cohesion. We suggest that more effort should be ...
    Keywords Collective behavior ; Vision ; Zebrafish ; Golden shiner ; Visual acuity ; Medicine ; R ; Biology (General) ; QH301-705.5
    Subject code 590
    Language English
    Publishing date 2015-08-01T00:00:00Z
    Publisher PeerJ Inc.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article: Serologic responses to peptides of Anaplasma phagocytophilum and Borrelia burgdorferi in dogs infested with wild-caught Ixodes scapularis

    Chandrashekar, R / B. Thatcher / J.M. Saucier / M.J. Beall / M.R. Lappin / P. Tyrrell

    veterinary journal. 2017 Aug., v. 226

    2017  

    Abstract: Anaplasma phagocytophilum and Borrelia burgdorferi are both transmitted by Ixodes spp. and are associated with clinical illness in some infected dogs. This study evaluated canine antibody responses to the A. phagocytophilum p44 peptides APH-1 and APH-4 ... ...

    Abstract Anaplasma phagocytophilum and Borrelia burgdorferi are both transmitted by Ixodes spp. and are associated with clinical illness in some infected dogs. This study evaluated canine antibody responses to the A. phagocytophilum p44 peptides APH-1 and APH-4 as well as the B. burgdorferi C6 peptide before and after doxycycline treatment. A total of eight dogs were infested with wild-caught I. scapularis for 1 week. Blood was collected prior to tick attachment and from Days 3–77 to 218–302 with doxycycline treatment beginning on Day 218. Blood was assayed for A. phagocytophilum DNA by PCR assay. Sera was assessed for antibodies by immunofluorescent antibody (IFA) test and ELISA. Anaplasma phagocytophilum DNA was amplified from blood of all dogs by Day 7. Antibodies to APH-4 were detected in serum as early as 14days after tick exposure and six dogs had APH-4 antibodies detected 3–7 days before antibodies against APH-1. All dogs were seropositive for A. phagocytophilum from Days 218 to 302. Antibodies to B. burgdorferi were detected in 6/8 dogs beginning 21days after I. scapularis infestation. Among the five dogs that remained seropositive at Day 218, C6 antibody levels declined on average 81% within 84days of initiating treatment. The results suggest that the APH-4 peptide may be more useful than APH-1 for detecting antibodies earlier in the course of an A. phagocytophilum infection. After doxycycline administration, C6 antibody levels but not APH-1 or APH-4 antibody levels decreased, suggesting a treatment effect on C6 antibody production.
    Keywords Anaplasma phagocytophilum ; antibodies ; antibody formation ; blood serum ; Borrelia burgdorferi ; DNA ; dog diseases ; dogs ; doxycycline ; enzyme-linked immunosorbent assay ; Ixodes scapularis ; peptides ; polymerase chain reaction ; seroprevalence ; ticks
    Language English
    Dates of publication 2017-08
    Size p. 6-11.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 428614-5
    ISSN 1532-2971 ; 0372-5545 ; 1090-0233
    ISSN (online) 1532-2971
    ISSN 0372-5545 ; 1090-0233
    DOI 10.1016/j.tvjl.2017.06.005
    Database NAL-Catalogue (AGRICOLA)

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  7. Article ; Online: P.014 VASCULAR MARKERS OF PREMATURE ATHEROSCLEROSIS IN PAEDIATRIC SYSTEMIC LUPUS ERYTHEMATOSUS AND DISEASE, THERAPY, METABOLIC AND INFLAMMATORY CORRELATES

    T. Bradley* / L. Nukumizu / C. Boros / C. Slorach / P. Tyrrell / M. Cheung / B. McCrindle / E. Silverman

    Artery Research, Vol 1, Iss

    2007  Volume 1

    Keywords Specialties of internal medicine ; RC581-951 ; Diseases of the circulatory (Cardiovascular) system ; RC666-701
    Language English
    Publishing date 2007-06-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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