THE CYTOSKELETAL SYSTEM OF THE NONMAMMALIAN VERTEBRATE ERYTHROCYTE.
Item
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Title
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THE CYTOSKELETAL SYSTEM OF THE NONMAMMALIAN VERTEBRATE ERYTHROCYTE.
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Identifier
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AAI8302491
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identifier
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8302491
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Creator
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BARTELT, DIANA CLAIRE.
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Contributor
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Willam D. Cohen
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Date
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1982
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, General
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Abstract
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Nonmammalian vertebrate erythrocytes are flattened elliptical nucleated cells with relatively few cytoplasmic organelles. Their cytoskeleton consists of a peripheral bundle of microtubules (marginal band; MB), surrounded by a cell surface associated cytoskeleton (SAC) and contains transcellular structures attached to the nucleus which include intermediate filaments. Dogfish erythrocyte cytoskeletons were examined for structural organization by phase contrast light microscopy and transmission electron microscopy. Anucleate dogfish erythrocyte cytoskeletons, consisting of MB and SAC, were prepared. Microtubules of dogfish erythrocyte MBs are cold labile in vivo. Anucleate cytoskeletons prepared from cooled cells devoid of MBs, contained spectrin-like proteins, actin, and possibly vimentin and goblin as their major protein constituents. Marginal bands, isolated from cytoskeletons, contained tubulin as their only major protein constituent.;Dogfish erythrocytes exhibited calcium-dependent changes in morphology when incubated with ionophore A23187. Calmodulin, a known mediator of the effects of calcium on both soluble and cytoskeletal proteins, was detected in erythrocyte lysates. Anucleate dogfish erythrocyte cytoskeletons bound calmodulin in a calcium-dependent manner, and contained one major calcium-dependent calmodulin-binding protein (CBP). CBP, with an apparent molecular weight of 245,000, comigrated with the upper bands of both dogfish and human spectrin. CBP was localized to the SAC, and was extracted with dogfish spectrin under conditions of low ionic strength. CBP was identified as fodrin, a protein localized in the SAC of non-erythroid cells of both non-mammalian and mammalian origin. Antibody to fodrin reacted strongly with CBP and weakly with human spectrin. Anti-human spectrin antibody bound to the lower band of dogfish spectrin and goblin, but not to CBP. These data suggest that spectrin diverged from fodrin during the evolution of erythrocytes from elliptical nucleated cells containing MBs in non-mammalian vertebrates to anucleate biconcave discoid cells, lacking these structures, in mammalian vertebrates.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Biology
