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  • 1
    Publication Date: 1990-01-01
    Print ISSN: 0032-2474
    Electronic ISSN: 1475-3057
    Topics: Ethnic Sciences , Geography
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  • 2
    Publication Date: 1994-09-01
    Description: Water soluble compounds were extracted from the dominant cryptogams of the Windmill Islands, Wilkes Land, and compared with standard polyols, sugars and amino acids using 13C nuclear magnetic resonance (NMR) spectroscopy. Previous findings for sugars and polyols from gas liquid chromatorgraphy were validated and extended. Arabitol, ribitol and mannitol were confirmed as the major soluble carbohydrate compounds in all lichen species examined. Sucrose, fructose and glucose, but no polyols were detected in two species of moss. Sorbitol was confirmed as a major component of the algae Prasiola crispa and Schizogonium murale. Mesotaenium bergrenii was confirmed to contain sucrose and glucose. No significant quantities of sugars or polyols or any other compound were found in extracts of the red snow alga Chloromonas sp.1. Amino acids were detected in the majority of cryptogam samples and were particularly abundant in the algae P. crispa and S. murale. In the latter species the total identified acids ranged from 13.5–66mg g-1 dry weight. In addition to the common amino acid components of proteins, betaine and γ-amino-butyric acid were detected, the latter being particularly abundant, being found widely in the moss, lichen and algae. Several unknown carbohydrates were characterized. Usnea sphacelata, U. antarctica and Pseudephebe minuscula contained a deoxy-hexitol, Grimmia antarctici contained resonance peaks consistent with a trisaccharide containing a sucrose moiety and Umbilicaria decussata possibly contained a glucose-arabitol dimer. 13C NMR was confirmed as a powerful tool for the characterization of low molecular weight constituents of Antarctic cryptogams.
    Print ISSN: 0954-1020
    Electronic ISSN: 1365-2079
    Topics: Biology , Geography , Geosciences
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  • 3
    Publication Date: 1994-03-01
    Description: In the cold Antarctic environment labile organic compounds may accumulate in soil due to relatively low utilization rates by heterotrophic microorganisms. Microbial fermentation of these compounds might contribute to the development of strongly acid soils. To test this and assess concentrations, extracts of a range of soils in the Windmill Islands, Budd Coast were analysed by GLC and HPLC for the presence of low molecular weight sugars, polyols and organic acids. Concentrations of sugars and polyols up to 3300 mg g−1 were detected in cryptogam dominated soils. Some, such as trehalose, may have principally originated in the soil microflora. Soils from occupied penguin rookeries were found to possess oxalic, acetic, propionic and succinic acids at levels up to 1000 mg g−1 soil. Most other soils, however, lacked these acids at detectable levels (1–5 mg g−1 soil). No correlation was established between organic acid accumulation and soil pH although those dominated by moss and lichen had been acidified significantly when compared with barren soils. Thus while substantial pools of these readily utilized carbohydrates were probably present in cryptogam dominated soils, there was little accumulation of organic acids which could account for the acidity of mineral soils typical of the Windmill Islands.
    Print ISSN: 0954-1020
    Electronic ISSN: 1365-2079
    Topics: Biology , Geography , Geosciences
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  • 4
    Publication Date: 1992-12-01
    Description: Healthy samples of Grimmia antarctici (turf and cushion ecodemes), Ceratodon purpureus, Bryum pseudotriquetrum and Cephaloziella exiliflora were collected in late summer in Wilkes Land together with senescing and dead G. antarctici material. Plant material was subjected to leaching in water and up to 16 freeze-thaw cycles. Gas chromatography revealed that following 16 days immersion, loss of carbohydrates (mainly glucose and fructose) was relatively low (c. 10–29% of the total sugar pool) for healthy material, with the loss of 69% from the dead G. antarctici material. Freeze-thaw cycles greatly increased rates of sucrose leakage and led to a 2–3 times rise in total sugar loss in all samples except the dead brown tissue which was not significantly different from the leached control treatment. After 16 freeze-thaw cycles Bryum pseudotriquetrum had lost 65% of total sugar pool. Losses for other species were below 28%. Differential thermal analyses showed freezing points of tissue varied from −8.3 to −3.5°C with dead material having the highest freezing temperatures. There was no significant correlation within species of freezing temperature changes with progressive sugar loss. The results are discussed in relation to nutrient cycling, soil microbial activity and the viability of bryophyte species in the Antarctic environment.
    Print ISSN: 0954-1020
    Electronic ISSN: 1365-2079
    Topics: Biology , Geography , Geosciences
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