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  1. Article ; Online: Temperature activated transient receptor potential ion channels from Antarctic fishes

    Julia M. York

    Open Biology, Vol 13, Iss

    2023  Volume 10

    Abstract: Antarctic notothenioid fishes (cryonotothenioids) live in waters that range between −1.86°C and an extreme maximum +4°C. Evidence suggests these fish sense temperature peripherally, but the molecular mechanism of temperature sensation in unknown. ... ...

    Abstract Antarctic notothenioid fishes (cryonotothenioids) live in waters that range between −1.86°C and an extreme maximum +4°C. Evidence suggests these fish sense temperature peripherally, but the molecular mechanism of temperature sensation in unknown. Previous work identified transient receptor potential (TRP) channels TRPA1b, TRPM4 and TRPV1a as the top candidates for temperature sensors. Here, cryonotothenioid TRPA1b and TRPV1a are characterized using Xenopus oocyte electrophysiology. TRPA1b and TRPV1a showed heat-evoked currents with Q10s of 11.1 ± 2.2 and 20.5 ± 2.4, respectively. Unexpectedly, heat activation occurred at a threshold of 22.9 ± 1.3°C for TRPA1b and 32.1 ± 0.6°C for TRPV1a. These fish have not experienced such temperatures for at least 15 Myr. Either (1) another molecular mechanism underlies temperature sensation, (2) these fishes do not sense temperatures below these thresholds despite having lethal limits as low as 5°C, or (3) native cellular conditions modify the TRP channels to function at relevant temperatures. The effects of osmolytes, pH, oxidation, phosphorylation, lipids and accessory proteins were tested. No conditions shifted the activity range of TRPV1a. Oxidation in combination with reduced cholesterol significantly dropped activation threshold of TRPA1b to 11.3 ± 2.3°C, it is hypothesized the effect may be due to lipid raft disruption.
    Keywords notothenioids ; TRP channels ; thermosensation ; ion channels ; Antarctica ; Biology (General) ; QH301-705.5
    Language English
    Publishing date 2023-10-01T00:00:00Z
    Publisher The Royal Society
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: A systems change framework for evaluating academic equity and inclusion in an Ecology and Evolution Graduate Program

    Kelly J. Wallace / Julia M. York

    Ecology and Evolution, Vol 10, Iss 20, Pp 10922-

    2020  Volume 10929

    Abstract: Abstract While academia is moving forward in terms of diversifying recruitment of undergraduate and graduate students, diverse representation is still not found across the academic hierarchy. At the graduate level, new discussions are emerging around ... ...

    Abstract Abstract While academia is moving forward in terms of diversifying recruitment of undergraduate and graduate students, diverse representation is still not found across the academic hierarchy. At the graduate level, new discussions are emerging around efforts to improve the experiences of women and underrepresented minorities through inclusive graduate programming. Inclusive graduate programs are that which actively center and prioritize support for diverse experiences, identities, career goals, and perspectives, from recruitment through graduation. Establishing regular and rigorous evaluation of equity and inclusion efforts and needs is a critical component of this work. This is recognized by funding agencies that increasingly require reporting on inclusion efforts; here, we suggest use of a systems change framework for these evaluations. A systems change approach emphasizes three levels: explicit change (e.g., policies), semi‐explicit change (e.g., power dynamics), and implicit change (e.g., biases). We use the Ecology, Evolution, and Behavior (EEB) PhD Program at the University of Texas at Austin in an exercise to (a) identify areas of concern regarding inclusive programming voiced by graduate students, (b) categorize efforts to address these concerns, and (c) integrating and evaluating which areas of the systems change framework show the greatest progress or potential for progress. We argue this framework is particularly useful for academic systems as they are complex, composed of variable individuals, and must address diverse stakeholder needs.
    Keywords climate ; diversity ; evaluation ; graduate students ; inclusion ; systems change ; Ecology ; QH540-549.5
    Subject code 333
    Language English
    Publishing date 2020-10-01T00:00:00Z
    Publisher Wiley
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: A potential cost of evolving epibatidine resistance in poison frogs

    Julia M. York / Cecilia M. Borghese / Andrew A. George / David C. Cannatella / Harold H. Zakon

    BMC Biology, Vol 21, Iss 1, Pp 1-

    2023  Volume 16

    Abstract: Abstract Background Some dendrobatid poison frogs sequester the toxin epibatidine as a defense against predators. We previously identified an amino acid substitution (S108C) at a highly conserved site in a nicotinic acetylcholine receptor β2 subunit of ... ...

    Abstract Abstract Background Some dendrobatid poison frogs sequester the toxin epibatidine as a defense against predators. We previously identified an amino acid substitution (S108C) at a highly conserved site in a nicotinic acetylcholine receptor β2 subunit of dendrobatid frogs that decreases sensitivity to epibatidine in the brain-expressing α4β2 receptor. Introduction of S108C to the orthologous high-sensitivity human receptor similarly decreased sensitivity to epibatidine but also decreased sensitivity to acetylcholine, a potential cost if this were to occur in dendrobatids. This decrease in the acetylcholine sensitivity manifested as a biphasic acetylcholine concentration–response curve consistent with the addition of low-sensitivity receptors. Surprisingly, the addition of the β2 S108C into the α4β2 receptor of the dendrobatid Epipedobates anthonyi did not change acetylcholine sensitivity, appearing cost-free. We proposed that toxin-bearing dendrobatids may have additional amino acid substitutions protecting their receptors from alterations in acetylcholine sensitivity. To test this, in the current study, we compared the dendrobatid receptor to its homologs from two non-dendrobatid frogs. Results The introduction of S108C into the α4β2 receptors of two non-dendrobatid frogs also does not affect acetylcholine sensitivity suggesting no additional dendrobatid-specific substitutions. However, S108C decreased the magnitude of neurotransmitter-induced currents in Epipedobates and the non-dendrobatid frogs. We confirmed that decreased current resulted from fewer receptors in the plasma membrane in Epipedobates using radiolabeled antibodies against the receptors. To test whether S108C alteration of acetylcholine sensitivity in the human receptor was due to (1) adding low-sensitivity binding sites by changing stoichiometry or (2) converting existing high- to low-sensitivity binding sites with no stoichiometric alteration, we made concatenated α4β2 receptors in stoichiometry with only high-sensitivity sites. S108C ...
    Keywords Evolution ; Nicotinic acetylcholine receptor ; Poison frog ; Epibatidine ; Epipedobates anthonyi ; Xenopus tropicalis ; Biology (General) ; QH301-705.5
    Subject code 572
    Language English
    Publishing date 2023-06-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Reduced metabolism supports hypoxic flight in the high-flying bar-headed goose (Anser indicus)

    Jessica U Meir / Julia M York / Bev A Chua / Wilhelmina Jardine / Lucy A Hawkes / William K Milsom

    eLife, Vol

    2019  Volume 8

    Abstract: The bar-headed goose is famed for migratory flight at extreme altitude. To better understand the physiology underlying this remarkable behavior, we imprinted and trained geese, collecting the first cardiorespiratory measurements of bar-headed geese ... ...

    Abstract The bar-headed goose is famed for migratory flight at extreme altitude. To better understand the physiology underlying this remarkable behavior, we imprinted and trained geese, collecting the first cardiorespiratory measurements of bar-headed geese flying at simulated altitude in a wind tunnel. Metabolic rate during flight increased 16-fold from rest, supported by an increase in the estimated amount of O2 transported per heartbeat and a modest increase in heart rate. The geese appear to have ample cardiac reserves, as heart rate during hypoxic flights was not higher than in normoxic flights. We conclude that flight in hypoxia is largely achieved via the reduction in metabolic rate compared to normoxia. Arterial [Formula: see text] was maintained throughout flights. Mixed venous PO2 decreased during the initial portion of flights in hypoxia, indicative of increased tissue O2 extraction. We also discovered that mixed venous temperature decreased during flight, which may significantly increase oxygen loading to hemoglobin.
    Keywords bar-headed goose ; hypoxia ; wind tunnel ; high altitude ; metabolic rate ; flight ; Medicine ; R ; Science ; Q ; Biology (General) ; QH301-705.5
    Subject code 610
    Language English
    Publishing date 2019-09-01T00:00:00Z
    Publisher eLife Sciences Publications Ltd
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Morphological and morphometric specializations of the lung of the Andean goose, Chloephaga melanoptera

    John N Maina / Kevin G McCracken / Beverly Chua / Julia M York / William K Milsom

    PLoS ONE, Vol 12, Iss 3, p e

    A lifelong high-altitude resident.

    2017  Volume 0174395

    Abstract: High altitude flight in rarefied, extremely cold and hypoxic air is a very challenging activity. Only a few species of birds can achieve it. Hitherto, the structure of the lungs of such birds has not been studied. This is because of the rarity of such ... ...

    Abstract High altitude flight in rarefied, extremely cold and hypoxic air is a very challenging activity. Only a few species of birds can achieve it. Hitherto, the structure of the lungs of such birds has not been studied. This is because of the rarity of such species and the challenges of preparing well-fixed lung tissue. Here, it was posited that in addition to the now proven physiological adaptations, high altitude flying birds will also have acquired pulmonary structural adaptations that enable them to obtain the large amounts of oxygen (O2) needed for flight at high elevation, an environment where O2 levels are very low. The Andean goose (Chloephaga melanoptera) normally resides at altitudes above 3000 meters and flies to elevations as high as 6000 meters where O2 becomes limiting. In this study, its lung was morphologically- and morphometrically investigated. It was found that structurally the lungs are exceptionally specialized for gas exchange. Atypically, the infundibulae are well-vascularized. The mass-specific volume of the lung (42.8 cm3.kg-1), the mass-specific respiratory surface area of the blood-gas (tissue) barrier (96.5 cm2.g-1) and the mass-specific volume of the pulmonary capillary blood (7.44 cm3.kg-1) were some of the highest values so far reported in birds. The pulmonary structural specializations have generated a mass-specific total (overall) pulmonary morphometric diffusing capacity of the lung for oxygen (DLo2) of 0.119 mlO2.sec-1.mbar-1.kg-1, a value that is among some of the highest ones in birds that have been studied. The adaptations of the lung of the Andean goose possibly produce the high O2 conductance needed to live and fly at high altitude.
    Keywords Medicine ; R ; Science ; Q
    Subject code 590
    Language English
    Publishing date 2017-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article: Oxygen in demand: How oxygen has shaped vertebrate physiology

    Dzal, Yvonne A / Julia M. York / Matthew E. Pamenter / Michelle N. Reichert / Sabine L. Lague / Sarah E.M. Jenkin

    Comparative biochemistry and physiology. 2015 Aug., v. 186

    2015  

    Abstract: In response to varying environmental and physiological challenges, vertebrates have evolved complex and often overlapping systems. These systems detect changes in environmental oxygen availability and respond by increasing oxygen supply to the tissues ... ...

    Abstract In response to varying environmental and physiological challenges, vertebrates have evolved complex and often overlapping systems. These systems detect changes in environmental oxygen availability and respond by increasing oxygen supply to the tissues and/or by decreasing oxygen demand at the cellular level. This suite of responses is termed the oxygen transport cascade and is comprised of several components. These components include 1) chemosensory detectors that sense changes in oxygen, carbon dioxide, and pH in the blood, and initiate changes in 2) ventilation and 3) cardiac work, thereby altering the rate of oxygen delivery to, and carbon dioxide clearance from, the tissues. In addition, changes in 4) cellular and systemic metabolism alters tissue-level metabolic demand. Thus the need for oxygen can be managed locally when increasing oxygen supply is not sufficient or possible. Together, these mechanisms provide a spectrum of responses that facilitate the maintenance of systemic oxygen homeostasis in the face of environmental hypoxia or physiological oxygen depletion (i.e. due to exercise or disease). Bill Milsom has dedicated his career to the study of these responses across phylogenies, repeatedly demonstrating the power of applying the comparative approach to physiological questions. The focus of this review is to discuss the anatomy, signalling pathways, and mechanics of each step of the oxygen transport cascade from the perspective of a Milsomite. That is, by taking into account the developmental, physiological, and evolutionary components of questions related to oxygen transport. We also highlight examples of some of the remarkable species that have captured Bill’s attention through their unique adaptations in multiple components of the oxygen transport cascade, which allow them to achieve astounding physiological feats. Bill’s research examining the oxygen transport cascade has provided important insight and leadership to the study of the diverse suite of adaptations that maintain cellular oxygen content across vertebrate taxa, which underscores the value of the comparative approach to the study of physiological systems.
    Keywords blood pH ; carbon dioxide ; detectors ; homeostasis ; leadership ; mechanics ; metabolism ; oxygen ; phylogeny ; signal transduction ; tissues ; vertebrates
    Language English
    Dates of publication 2015-08
    Size p. 4-26.
    Publishing place Elsevier Inc.
    Document type Article
    ZDB-ID 121246-1
    ISSN 1531-4332 ; 0300-9629 ; 1095-6433
    ISSN (online) 1531-4332
    ISSN 0300-9629 ; 1095-6433
    DOI 10.1016/j.cbpa.2014.10.029
    Database NAL-Catalogue (AGRICOLA)

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