Biological basis of recognition, establishment and maintenance of diatom endosymbiosis in larger foraminifera.
Item
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Title
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Biological basis of recognition, establishment and maintenance of diatom endosymbiosis in larger foraminifera.
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Identifier
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AAI9908302
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identifier
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9908302
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Creator
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Chai, Jianyuan.
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Contributor
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Adviser: John J. Lee
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Date
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1998
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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, Ecology | Biology, Cell | Biology, Oceanography | Biology, Botany
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Abstract
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Evidence shows that the foraminifer Amphistegina lobifera can bear quite a number of different species of diatoms as endosymbionts but treats other diatoms as food. This suggests that the symbiotic diatoms must have something in common that makes them all acceptable to the same host. By comparing the molecular constitution of the organic coat of frustules from 11 species of symbiotic diatoms and 5 species of nonsymbiotic diatoms, a 104kDa glycoprotein (CSSA, Common Symbiotic Surface Antigen) was found only in the symbiotic species. Coating diatoms with the antibody against this protein significantly reduced uptake of the symbiotic species as well as incorporation of these diatoms into the host as symbionts. Apparently this protein is involved in the host-symbiont recognition. Immuno-gold localization indicated that there were receptors for the CSSA on the surface of the host pseudopodia, the primary organic membrane of the cell body, and pore organic linings. This suggests that the host recognizes its potential symbionts through a signal-receptor interaction of their surface molecules. After being internalized by a host, diatoms were liberated from their frustules. The frustules were wrapped in vacuoles with multiple membranes and digested. Removing frustules did not eliminate the CSSA protein from the diatom protoplasts. Immuno-gold labelling showed that this molecule is presented in diatom protoplast, especially on chloroplasts, during and after establishment of endosymbiosis. This suggests that the CSSA is related with the proper function of diatom chloroplasts. When the antibody against CSSA was applied in vivo to a host bearing mature symbiotic diatoms, the symbionts were digested. This means that this protein is not only needed for the initial host-symbiont recognition, it is also necessary for the establishment and maintenance of this symbiotic relationship. A healthy symbiont, during and after the establishment, was closely associated with host organelles such as mitochondria, rough endoplasmic reticulum, and Golgi apparatus. This suggests that the host incorporates symbionts as parts of its own compartments by modifying them and taking over some of their cellular functions.
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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.
