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Metabolic Engineering in Plants to Control Source/sink Relationship and Biomass Distribution

Metabolic Engineering in Plants to Control Source/sink Relationship and Biomass Distribution

Date: August 2013
Creator: Lahiri, Ipsita
Description: Traditional methods like pruning and breeding have historically been used in crop production to divert photoassimilates to harvested organs, but molecular biotechnology is now poised to significantly increase yield by manipulating resource partitioning. It was hypothesized that metabolic engineering in targeted sink tissues can favor resource partitioning to increase harvest. Raffinose Family Oligosaccharides (RFOs) are naturally occurring oligosaccharides that are widespread in plants and are responsible for carbon transport, storage and protection against cold and drought stress. Transgenic plants (GRS47, GRS63) were engineered to generate and transport more RFOs through the phloem than the wild type plants. The transgenic lines produced more RFOs and the RFOs were also detected in their phloem exudates. But the 14CO2 labeling and subsequent thin layer chromatography analysis showed that the RFOs were most likely sequestered in an inactive pool and accumulate over time. Crossing GRS47 and GRS63 lines with MIPS1 plants (that produces more myo-inositol, a substrate in the RFO biosynthetic pathway) did not significantly increase the RFOs in the crossed lines. For future manipulation of RFO degradation in sink organs, the roles of the endogenous α-galactosidases were analyzed. The alkaline α-galactosidases (AtSIP1 and AtSIP2 in Arabidopsis) are most likely responsible for digesting RFOs ...
Contributing Partner: UNT Libraries
Metabolic Engineering of Raffinose-Family Oligosaccharides in the Phloem Reveals Alterations in Patterns of Carbon Partitioning and Enhances Resistance to Green Peach Aphid

Metabolic Engineering of Raffinose-Family Oligosaccharides in the Phloem Reveals Alterations in Patterns of Carbon Partitioning and Enhances Resistance to Green Peach Aphid

Date: August 2010
Creator: Cao, Te
Description: Phloem transport is along hydrostatic pressure gradients generated by differences in solute concentration between source and sink tissues. Numerous species accumulate raffinose-family oligosaccharides (RFOs) in the phloem of mature leaves to accentuate the pressure gradient between source and sinks. In this study, metabolic engineering was used to generate RFOs at the inception of the translocation stream of Arabidopsis thaliana, which transports predominantly sucrose. To do this, three genes, GALACTINOL SYNTHASE, RAFFINOSE SYNTHASE and STACHYOSE SYNTHASE, were expressed from promoters specific to the companion cells of minor veins. Two transgenic lines homozygous for all three genes (GRS63 and GRS47) were selected for further analysis. Sugars were extracted and quantified by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), and 21-day old plants of both lines had levels of galactinol, raffinose, and stachyose approaching 50% of total soluble sugar. All three exotic sugars were also identified in phloem exudates from excised leaves of transgenic plants whereas levels were negligible in exudates from wild type leaves. Differences in starch accumulation or degradation between wild type and GRS63 and GRS47 lines were not observed. Similarly, there were no differences in vegetative growth between wild type and engineered plants, but engineered plants flowered ...
Contributing Partner: UNT Libraries
Metabolic Syndrome and Psychosocial Factors

Metabolic Syndrome and Psychosocial Factors

Date: August 2009
Creator: Tweedy, Maureen P.
Description: Metabolic syndrome is a constellation of risk factors, including abdominal obesity, hypertriglyceridemia, low HDL cholesterol, high blood pressure, and high fasting glucose, that commonly cluster together and can result in cardiovascular disease. The prevalence of metabolic syndrome and the components that comprise the syndrome vary by age and by racial/ethnic group. In addition, previous research has indicated that the risk factors contributing to metabolic syndrome may be exacerbated by exposure to perceived stress. This study utilized data from the 2002, 2004, and 2006 Health and Retirement Study (HRS) and National Health and Nutrition Examination Survey (NHANES) data sets. It was hypothesized that depression and anxiety (conceptualized as stress in this study) increase the risk of presenting with metabolic syndrome while social support decreases the risk of metabolic syndrome. While results of cross-sectional analysis do not indicate a significant relationship between depression and metabolic syndrome (t = -.84, ns), longitudinal analysis does indicate a significant relationship between depression and metabolic syndrome over time (t = -5.20, p <.001). However, anxiety is not significantly related to metabolic syndrome when the relationship is examined through cross-sectional analysis (t = -1.51, ns) and longitudinal analysis (&#967;² = 13.83, ns). Similarly, social support is not ...
Contributing Partner: UNT Libraries
Metabolism of Hydrocortisone by X-Irradiated Rat Liver Tissue as Determined by the Porter-Silber Chromagen Method

Metabolism of Hydrocortisone by X-Irradiated Rat Liver Tissue as Determined by the Porter-Silber Chromagen Method

Date: August 1959
Creator: Pryor, Nan Webb
Description: The present study may be considered endocrinological and radiobiological in nature. The endocrinology phase was concerned with studying the changes in endocrine function following the application of a stress agent. X-irradiation was chosen as the stressor in order to determine any difference in effect of this stressor from others which have been studied, e. g. heat, cold, metabolic poisons. Liver slices taken from rats at various time intervals following whole body X-irradiation were tested for their ability to metabolize hydrocortisone from a Krebs-Ringer solution.
Contributing Partner: UNT Libraries
Metabolism of Methylglyoxal by Scenedesmus Quadricauda

Metabolism of Methylglyoxal by Scenedesmus Quadricauda

Date: June 1970
Creator: Rounsavall, Terry Yale
Description: The purpose of this study was to investigate the metabolic pathways of methylglyoxal in S. quadricauda.
Contributing Partner: UNT Libraries
The MetaCombine Project

The MetaCombine Project

Date: December 2004
Creator: Krowne, Aaron; Ingram, Stephen; Pathak, Saurabh & Halbert, Martin
Description: This poster presentation discusses the MetaCombine project, a Mellon-funded effort based at Emory University, with the goal of discovering and developing systems and methods to more meaningfully combine digital libraries, digital library resources, and digital library services.
Contributing Partner: UNT Libraries
Metadata Analysis at the Command-Line

Metadata Analysis at the Command-Line

Date: January 15, 2013
Creator: Phillips, Mark Edward
Description: This article discusses metadata analysis tools, processes, and methodologies aimed at helping to focus limited quality control resources on the areas of the collection where they might have the most benefit.
Contributing Partner: UNT Libraries
Metadata and XML

Metadata and XML

Date: November 7, 2003
Creator: Phillips, Mark Edward
Description: This presentation discusses how XML can help store metadata. The University of North Texas (UNT) Digital Projects Unit developed the UNTL metadata element set with IndexData that tailored the data to meet their needs.
Contributing Partner: UNT Libraries
A Metadata Approach to Preservation of Digital Resources: The University of North Texas Libraries' Experience

A Metadata Approach to Preservation of Digital Resources: The University of North Texas Libraries' Experience

Date: August 2002
Creator: Alemneh, Daniel Gelaw; Hastings, Samantha Kelly & Hartman, Cathy Nelson
Description: Article discussing metadata approaches to preservation of digital resources and the experiences of the University of North Texas (UNT) Libraries.
Contributing Partner: UNT Libraries
Metadata: Batch Editing of MARC Records (work area D)

Metadata: Batch Editing of MARC Records (work area D)

Date: May 2, 2007
Creator: Phillips, Mark Edward & Polyakov, Serhiy
Description: Report for an Institute of Museum and Library Sciences (IMLS) Grant Partner Uplift Project. This reports workflows developed for the conversion of two sets of metadata records and serves the following objectives: research different avenues for the batch import and export of MARC records from popular integrated library systems, identify tools/software which aids in batch editing of MARC records, and document workflow for batch editing MARC records.
Contributing Partner: UNT Libraries