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Characterization Of The Expression Profile Of Polyamine Biosynthetic Genes (Spermidine Synthase) And Polyamine Metabolic Regulation In Arabidopsis, Lin Shao

Doctoral Dissertations

Polyamines are ubiquitously distributed cationic compounds, which play important roles in numerous cellular functions in plants. This study was aimed at elaborating the regulation of polyamine biosynthetic gene expression and polyamine metabolism. The organ/tissue specific expression patterns of two genes encoding the polyamine biosynthetic enzyme spermidine synthase ( AtSPDS1 and AtSPDS2) were studied in Arabidopsis at different developmental stages using promoter::reporter approach. The two homologues showed similar ubiquitous expression with subtle differences being observed in certain tissues (e.g. root, siliques, and embryos). Neither transgenic manipulation by over-expression of AtSPDSI alone nor its concomitant expression with genes encoding other biosynthetic enzymes …

Engineering Lipases And Solvents For Trans/-Esterification Of Used Vegetable Oils, Michael Dore Gagnon

Doctoral Dissertations

Diminishing petroleum reserves and increasing environmental awareness has led to an urgent need to develop alternative fuels, such as biodiesel. However, the conventional method to produce biodiesel uses environmentally harmful chemical catalysts. A relatively new development in the production of biodiesel is through enzymatic trans/- esterification with a lipase catalyst. Despite several advantages, there are a few technical and economical obstacles that limit this process: (1) immiscibility of the hydrophilic methanol and hydrophobic triglyceride which results in the formation of an interface leading to mass transfer resistance, (2) insufficient availability of large quantities of inexpensive lipase suitable for catalysis, and …

Response Of Tree Growth And Water Use Efficiency To Climate And Nitrogen Deposition In A Temperate Deciduous Forest In The Northeastern Us, Katie Jennings

Master's Theses and Capstones

Nitrogen (N) deposition and climate change are altering tree growth and may have important consequences for water use in northeastern forests. Intrinsic water use efficiency (iWUE), the trade-off between water loss and carbon fixed during photosynthesis, directly links forest carbon and water cycles. Dendrochronology and stable isotopes (delta13C and delta18O) were used to assess Quercus velutina growth and iWUE within a chronic N deposition experiment (20+ years of fertilization at low- and high-N rates). Fertilized trees exhibited sustained growth enhancement, with the greatest response observed for high-N trees. All fertilized trees improved their iWUE through increased photosynthetic rates, but was …

Viability Of Butternut (Juglans Cinerea L) In The Northeastern United States: An Assessment Of The Genetic Diversity, Health, And Hybridization And Recruitment Of Butternut In The Northeast, Andre A W Boraks

Master's Theses and Capstones

Butternut (Juglans cinerea) trees are being extirpated from their natural range by means of an epidemic caused by a fungal pathogen. Widespread mortality is reminiscent of past epidemics on American chestnut (Castanea dentata) and American elm (Ulmus americana ). Understanding the course of contemporary decline of this tree species will provide greater insight on processes of potential extinction and the results of management to prevent it.

This thesis applies an interdisciplinary approach to characterize butternut of the northeastern Unites States. While there is evidence of weak genetic structuring, butternut appears to have maintained sufficient dispersal to prevent isolation and inbreeding …