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      Reptile-like physiology in Early Jurassic stem-mammals

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          Abstract

          Despite considerable advances in knowledge of the anatomy, ecology and evolution of early mammals, far less is known about their physiology. Evidence is contradictory concerning the timing and fossil groups in which mammalian endothermy arose. To determine the state of metabolic evolution in two of the earliest stem-mammals, the Early Jurassic Morganucodon and Kuehneotherium, we use separate proxies for basal and maximum metabolic rate. Here we report, using synchrotron X-ray tomographic imaging of incremental tooth cementum, that they had maximum lifespans considerably longer than comparably sized living mammals, but similar to those of reptiles, and so they likely had reptilian-level basal metabolic rates. Measurements of femoral nutrient foramina show Morganucodon had blood flow rates intermediate between living mammals and reptiles, suggesting maximum metabolic rates increased evolutionarily before basal metabolic rates. Stem mammals lacked the elevated endothermic metabolism of living mammals, highlighting the mosaic nature of mammalian physiological evolution.

          Abstract

          Modern mammals are endothermic, but it has not been clear when this type of metabolism evolved. Here, Newham et al. analyse tooth and bone structure in Early Jurassic stem-mammal fossils to estimate lifespan and blood flow rates, which inform about basal and maximum metabolic rates, respectively, and show these stem-mammals had metabolic rates closer to modern ectothermic reptiles than to endothermic mammals.

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          NIH Image to ImageJ: 25 years of image analysis

          For the past twenty five years the NIH family of imaging software, NIH Image and ImageJ have been pioneers as open tools for scientific image analysis. We discuss the origins, challenges and solutions of these two programs, and how their history can serve to advise and inform other software projects.
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            Simultaneous phase and amplitude extraction from a single defocused image of a homogeneous object.

            We demonstrate simultaneous phase and amplitude extraction from a single defocused image of a homogeneous object. Subject to the assumptions explicitly stated in the derivation, the algorithm solves the twin-image problem of in-line holography and is capable of analysing data obtained using X-ray microscopy, electron microscopy, neutron microscopy or visible-light microscopy, especially as they relate to defocus and point projection methods. Our simple, robust, non-iterative and computationally efficient method is applied to data obtained using an X-ray phase contrast ultramicroscope.
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              Life and death: metabolic rate, membrane composition, and life span of animals.

              Maximum life span differences among animal species exceed life span variation achieved by experimental manipulation by orders of magnitude. The differences in the characteristic maximum life span of species was initially proposed to be due to variation in mass-specific rate of metabolism. This is called the rate-of-living theory of aging and lies at the base of the oxidative-stress theory of aging, currently the most generally accepted explanation of aging. However, the rate-of-living theory of aging while helpful is not completely adequate in explaining the maximum life span. Recently, it has been discovered that the fatty acid composition of cell membranes varies systematically between species, and this underlies the variation in their metabolic rate. When combined with the fact that 1) the products of lipid peroxidation are powerful reactive molecular species, and 2) that fatty acids differ dramatically in their susceptibility to peroxidation, membrane fatty acid composition provides a mechanistic explanation of the variation in maximum life span among animal species. When the connection between metabolic rate and life span was first proposed a century ago, it was not known that membrane composition varies between species. Many of the exceptions to the rate-of-living theory appear explicable when the particular membrane fatty acid composition is considered for each case. Here we review the links between metabolic rate and maximum life span of mammals and birds as well as the linking role of membrane fatty acid composition in determining the maximum life span. The more limited information for ectothermic animals and treatments that extend life span (e.g., caloric restriction) are also reviewed.
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                Author and article information

                Contributors
                en12630@bristol.ac.uk
                pam.gill@bristol.ac.uk
                ian.corfe@helsinki.fi
                Journal
                Nat Commun
                Nat Commun
                Nature Communications
                Nature Publishing Group UK (London )
                2041-1723
                12 October 2020
                12 October 2020
                2020
                : 11
                : 5121
                Affiliations
                [1 ]GRID grid.5337.2, ISNI 0000 0004 1936 7603, School of Physiology, Pharmacology & Neuroscience, , University of Bristol, ; Bristol, UK
                [2 ]GRID grid.5491.9, ISNI 0000 0004 1936 9297, Bioengineering Science Research Group, Faculty of Engineering and Physical Sciences, , University of Southampton, ; Southampton, UK
                [3 ]GRID grid.5337.2, ISNI 0000 0004 1936 7603, School of Earth Sciences, , University of Bristol, ; Bristol, UK
                [4 ]GRID grid.35937.3b, ISNI 0000 0001 2270 9879, Earth Sciences Department, , The Natural History Museum, ; London, UK
                [5 ]GRID grid.35937.3b, ISNI 0000 0001 2270 9879, Core Research Laboratories, , The Natural History Museum, ; London, UK
                [6 ]GRID grid.5398.7, ISNI 0000 0004 0641 6373, ESRF, The European Synchrotron, ; Grenoble, France
                [7 ]GRID grid.5491.9, ISNI 0000 0004 1936 9297, School of Biological Sciences, , University of Southampton, ; Southampton, UK
                [8 ]GRID grid.5991.4, ISNI 0000 0001 1090 7501, Swiss Light Source, , Paul Scherrer Institut, ; Villigen, Switzerland
                [9 ]GRID grid.5734.5, ISNI 0000 0001 0726 5157, Institute of Anatomy, , University of Bern, ; Bern, Switzerland
                [10 ]GRID grid.7737.4, ISNI 0000 0004 0410 2071, Institute of Biotechnology, , University of Helsinki, ; Helsinki, Finland
                [11 ]GRID grid.7737.4, ISNI 0000 0004 0410 2071, Department of Agricultural Sciences, , University of Helsinki, ; Helsinki, Finland
                [12 ]GRID grid.7737.4, ISNI 0000 0004 0410 2071, Department of Physics, , University of Helsinki, ; Helsinki, Finland
                [13 ]GRID grid.440504.1, ISNI 0000 0000 8693 4250, Oxford University Museum of Natural History, ; Oxford, UK
                [14 ]GRID grid.5337.2, ISNI 0000 0004 1936 7603, Department of Anthropology and Archaeology, , University of Bristol, ; Bristol, UK
                [15 ]GRID grid.24999.3f, ISNI 0000 0004 0541 3699, Institute for Materials Research, Division of Metallic Biomaterials, , Helmholtz Zentrum Geesthacht, ; Geesthacht, Germany
                [16 ]GRID grid.52593.38, ISNI 0000000123753425, Geomaterials and Applied Mineralogy group, , Geological Survey of Finland, ; Espoo, Finland
                Author information
                http://orcid.org/0000-0002-3365-3943
                http://orcid.org/0000-0001-5957-3581
                http://orcid.org/0000-0001-7728-1021
                http://orcid.org/0000-0002-4323-1824
                http://orcid.org/0000-0002-5960-7769
                http://orcid.org/0000-0003-3388-9187
                http://orcid.org/0000-0003-3269-0299
                http://orcid.org/0000-0003-2306-7040
                http://orcid.org/0000-0003-4797-8965
                http://orcid.org/0000-0001-7499-3576
                http://orcid.org/0000-0002-5962-1683
                http://orcid.org/0000-0002-7562-9423
                http://orcid.org/0000-0002-1824-755X
                Article
                18898
                10.1038/s41467-020-18898-4
                7550344
                33046697
                e9c70184-c740-44af-af09-2fe8420d848f
                © The Author(s) 2020

                Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

                History
                : 1 November 2019
                : 11 September 2020
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                © The Author(s) 2020

                Uncategorized
                palaeontology,animal physiology
                Uncategorized
                palaeontology, animal physiology

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