CYTOLOGICAL INVESTIGATION OF DIGESTION AND RE-ESTABLISHMENT OF SYMBIOSIS IN THE LARGER BENTHIC FORAMINIFER AMPHISTEGINA LESSONII.
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Title
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CYTOLOGICAL INVESTIGATION OF DIGESTION AND RE-ESTABLISHMENT OF SYMBIOSIS IN THE LARGER BENTHIC FORAMINIFER AMPHISTEGINA LESSONII.
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Identifier
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AAI8508709
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identifier
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8508709
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Creator
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KOESTLER, ROBERT JOHN.
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Contributor
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John J. Lee
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Date
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1985
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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, Oceanography
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Abstract
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The fine structure of specimens of the larger foraminifera Amphistegina lessonii was studied with the aim of clarifying aspects of experimentally induced resynthesis of symbiosis, and comparing that to normal formal uptake.;Normal healthy foraminifera had one to three layers of symbionts within the dorsal and dorsal-lateral regions of cytoplasm, inside the shell. The cytoplasm behind the endosymbionts was dense and filled with vacuoles of all sizes, food particles, and some apparently normal endosymbionts. Undigested algae ultrastructurally similar to the endosymbionts were found in all chambers.;Food organisms Chlorella sp (AT) and Amphora sp (BL 45), and previously isolated and cultured algal endosymbionts Nitzschia laevis and Fragilaria shiloi were all contacted and transported by A. lessonii into the aperture in a similar manner. Fine pseudopodia attached and pulled the captured particles close to the shell and eventually through the aperture into the animal. Digestion of Chlorella sp (AT) and Amphora sp (BL 45) began outside soon after contact. Not all individuals of the endosymbiont species tested were digested. N. laevia were much more resistant to digestion than were F. shiloi.;All of the endosymbionts harbored in A. lessonii had pyrenoids with simple internal lamellae identical to those from cultures of N. laevis, N. panduriformis, and F. shiloi.;Incubation with the herbicide DCMU for 120 h bleached most of A. lessonii's endosymbionts and reduced their total numbers in the cortical cytoplasm. The endosymbionts remaining after DCMU treatment characteristically had closely packed chloroplast lamellae and lacked stored starch.;To explain why some diatoms persist while others are digested, evidence is presented for host selectivity and/or algal survival mechanisms of varying effectiveness. Whether or not the frustule-less diatoms which are found in the animals reproduce within the foraminifera in nature or if they are recruited continually from the environment is not known, but in culture it is clear that depleted populations repopulate their host without addition of new symbionts. Isolations from the field collections and the present experimental results suggest that there is an order of preference among potential endosymbionts. Fragilaria shiloi and Nitzschia panduriformis were low in the order of preference of these brief experiments, and yet they have been frequently isolated from the three collecting sites (Red Sea, Hawaii, and Great Barrier Reef). It is therefore obvious by analogy to the Convoluta roscoffensis system that time or other factors may be involved in selective algal persistence. (Abstract shortened with permission of author.).
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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
