Aluminum resistance of mycorrhizal plants

Aluminum (Al) in acidic soils is toxic to plants, affecting growth, water uptake, and nutrient assimilation. Aluminum resistance of plants has been ascribed to organic acid exudation from roots and changes in plant physiology resulting from the arbuscular mycorrhizal (AM) fungal symbiosis. This dissertation describes four studies that address questions regarding Al resistance of mycorrhizal plants.;In chapter 2, Liriodendron tulipifera, a common tree species in northeastern U.S. forests, was inoculated with several species of AM fungi and exposed to Al. Biomass and plant nutritional data showed that the AM species Glomus clarum conferred the most benefit to plant hosts. Organic acids exuded from roots, which can chelate and detoxify Al in root zones, appeared to be related the observed benefit of plants colonized by this species. In chapters 3 and 5, when Andropogon virginicus, an early successional species that colonizes disturbed soils, was inoculated with several AM species and isolates, plants colonized by G. clarum were larger than plants colonized by other species. However, organic acid exudation was not clearly associated with the growth benefits observed in plants in these experiments. In chapter 5, trends in the data showed that, under Al exposure, plants were larger when colonized by AM inoculum cultivated under prior Al exposure. The combined results of these studies illustrate functional variation among AM fungi and the importance of AM diversity in ecosystems. Additionally, cultivation of AM fungi under stressful conditions could enhance the stress resistance of AM fungi through the selection of stress resistance genotypes.;A field study, described in chapter 4, explored the relationship between plant succession and Al availability on the extreme soils of an abandoned coal mine. Concentrations of phytotoxic Al were low in vegetated areas compared to non-vegetated ones. Soil solution pH and organic acid concentrations were higher in vegetated locations at the end of the growing season and may be related to increased exudation as plants reached maturity or increases in decomposing leaf litter from senescing plants. Initial colonization of extreme sites by A. virginicus may ameliorate the low pH and Al conditions, facilitating ecological succession with other plant species

The dental calculus metabolome in modern and historic samples.

INTRODUCTION: Dental calculus is a mineralized microbial dental plaque biofilm that forms throughout life by precipitation of salivary calcium salts. Successive cycles of dental plaque growth and calcification make it an unusually well-preserved, long-term record of host-microbial interaction in the archaeological record. Recent studies have confirmed the survival of authentic ancient DNA and proteins within historic and prehistoric dental calculus, making it a promising substrate for investigating oral microbiome evolution via direct measurement and comparison of modern and ancient specimens. OBJECTIVE: We present the first comprehensive characterization of the human dental calculus metabolome using a multi-platform approach. METHODS: Ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) quantified 285 metabolites in modern and historic (200 years old) dental calculus, including metabolites of drug and dietary origin. A subset of historic samples was additionally analyzed by high-resolution gas chromatography-MS (GC-MS) and UPLC-MS/MS for further characterization of metabolites and lipids. Metabolite profiles of modern and historic calculus were compared to identify patterns of persistence and loss. RESULTS: Dipeptides, free amino acids, free nucleotides, and carbohydrates substantially decrease in abundance and ubiquity in archaeological samples, with some exceptions. Lipids generally persist, and saturated and mono-unsaturated medium and long chain fatty acids appear to be well-preserved, while metabolic derivatives related to oxidation and chemical degradation are found at higher levels in archaeological dental calculus than fresh samples. CONCLUSIONS: The results of this study indicate that certain metabolite classes have higher potential for recovery over long time scales and may serve as appropriate targets for oral microbiome evolutionary studies

Constructing musical associations through instruments : the role of the instrument maker in the maker-instrument-player network within the neo-medievalist gothic music scene

Many studies of musical instruments have shown the ways in which instruments embody and negotiate cultural and social significance and meaning, but little of this work has focused on the makers of those instruments. According to Alfred Gell, artisans infuse "intentionalities" into their wares that embody the agency of the artisan. In this thesis, I address the agency of makers of musical instruments to gain a better understanding of the roles they play in defining how instruments acquire their social and cultural meanings. These meanings are constantly in flux and, in turn, inform the maker's decisions and assist in formulating a maker's role within a musical community. Makers interact with community members primarily through the construction of their instruments as part of what I have called a Maker-Instrument-Player network. Drawing on Actor-Network Theory, I outline some of the ways in which musical instruments afford associations and engender exchanges within a musical community, and I unpack the complexities of the maker's role. Based on ethnographic case studies which feature contemporary builders of early music instruments and performers of neo-Medievalist Gothic music with whom they interact, I examine the agency and impact of instrument makers on musical processes. This includes analysis of playing techniques, concepts of authenticity and historical accuracy, perceptions of modernity and tradition, sensibilities of craftsmanship, the economics and marketing involved, and the physical attributes of the instruments themselves.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Asplenium scolopendrium

Pteridophyte

NOTES ON THE ALGAE OF GEORGIAN BAY

Volume: 15Start Page: 88End Page: 9