Elater and capsule wall differentiation in selected hepatics: A comparison to xylogenesis.
Item
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Title
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Elater and capsule wall differentiation in selected hepatics: A comparison to xylogenesis.
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Identifier
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AAI9207101
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identifier
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9207101
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Creator
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Mankiewicz, Julie A.
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Contributor
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Adviser: Dominick V. Basile
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Date
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1991
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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, Botany | Biology, Cell
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Abstract
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Hepatic elaters possess annular to helical secondary cell wall thickenings with as-yet unknown materials selectively deposited in these thickenings at maturity. These cells possess a striking similarity to higher plant protoxylem at the light microscope level. Differentiation was examined at the light and electron microscope levels, and compared to xylogenesis. Histochemical and biochemical analyses were utilized to attempt to determine whether lignin deposition occurred.;This is the first report in elaters of processes of secondary cell wall deposition nearly identical to that reported in xylogenesis, including microtubular arrays correlated with the direction of microfibril orientation in developing walls. Two phenomena strikingly different from xylogenesis were observed: severing of plasmodesmatal connections with adjoining cells prior to differentiation, and deposition of two successive waves of natively electron-dense materials during maturation of the secondary thickenings.;Histochemical and biochemical analyses of P. epiphylla sporangia revealed no strong evidence for the presence of lignin. While IKI-H{dollar}\sb2{dollar}SO{dollar}\sb4{dollar} reactions were similar to that of lignified cells, Maule and phloroglucinol tests were negative. Thioacidolysis extraction revealed a complete absence of {dollar}\beta{dollar}-0-4 lignin in all mosses and liverworts tested. While pyrolysis of P. epiphylla sporangia yielded breakdown products characteristic of guaicyl and hydroxyphenyl lignin, including those with vinyl and propenyl side chains, it was suspected that these results were due to phenolics other than lignin. To support this, saponification coupled with gas-chromatography revealed the presence of lignin precursors p-coumaric and ferulic acids in both ester and ether linked forms. UV microscopy demonstrated that ferulic acid was present in all primary walls but absent or obscured in the secondary thickenings. It is suggested that, rather than lignin, these ferulic and p-coumaric acids may be responsible for the putative lignin breakdown products produced during pyrolysis.
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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.
