Studies of Fossil and Modern Spore Wall Biomacromolecules using13C Solid State NMR |
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Authors: | HEMSLEY ALAN R; SCOTT ANDREW C; BARRIE PATRICK J; CHALONER WILLIAM G |
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Institution: | Department of Earth Sciences, University of Wales, Cardiff, PO Box 914, Cardiff, CF1 3YE, U.K. Department of Geology, Royal Holloway University of London, Egham, Surrey, U.K. Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London, WC1H 0AJ, U.K. |
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Abstract: | A range of Carboniferous lycophyte megaspore exines have beeninvestigated using13C magic-angle spinning nuclear magneticresonance (MAS NMR) spectroscopy. Their composition differsconsiderably from sporopollenin obtained from an extant lycophyte.The differences observed result in part from varying degreesof diagenesis. Fossil fern spores, gymnosperm megaspore-membranes and pollenhave also been examined. These show a similar composition tothe fossil lycophyte megaspores. The constituent material ofall of these exines differs considerably from the sporopolleninobtained from comparable extant samples. Despite the changesin composition observed on fossilisation, differences in compositionbetween the major groups of plants may be preserved to someextent in the fossil material. Walls of the fossil prasinophyceanalgal cystTasmanites have been examined and these show a greatersimilarity to fossil cuticle and algaenans than to sporopollenins. The effect of oxidative maceration on fossil and modern sporopolleninshas also been investigated. The main influence of oxidativemaceration is the removal of unsaturated carbon environmentssuch as aromatics; this causes fossil spores to be more susceptibleto oxidative maceration than the modern exines. Heating of modernexine material models the alteration of exines by diagenesis.The changes that occur on heating an extant sample to 150225°Cgive a chemical composition that is similar to those of thefossil sporopollenins. 13C solid state NMR; spores; pollen; fossil; Carboniferous lycopsids; ferns; pteridosperm; gymnosperm; oxidative maceration; heating; thermal maturation |
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