Entries tagged with “thesis” from College of Sciences

On February 9, 2012, Vitaliy Shkolnik successfully defended his Master’s thesis, entitled “Purine Metabolite Effects on Growth and Oxidative Signaling in Plants.” His work was conducted in the Department of Biological Sciences at UMass Lowell.

Shkolnik’s work was advised by Dr. Deane Falcone, and supported in part with funding from a grant from Syngenta Biotechnology, a major plant biotechnology research and development firm.

Shkolnik’s research employed the model plant Arabidopsis thaliana with which the Falcone Lab had discovered a unique metabolite signaling system that appears to prime plants to better tolerate stresses such as heat and drought. Major insight into the metabolic changes within the plant was recently unveiled in work in the same lab by graduate student Patrizia Stalder, who completed her PhD in August 2011.

The investigations described in Stadler’s dissertation served as the background for Shkolnik to further dissect possible mechanisms in the stress-tolerant line. Because drought is the cause of up to 50% crop yield losses in agriculture, the work is significant as an enabling technology. The prospect of using such technology in crops is underscored by the interest and support from industry.

Shkolnik’s research focused on investigating the effects of purine metabolites implicated in promoting enhanced growth and tolerance. His work employed developing plant cell cultures to test whether reactive oxygen species were involved in signaling once changes in purine levels were triggered in response to stress, a finding also stemming from Stadler’s PhD research.

The results showed that exogenously provided purines can induce increases in reactive oxygen species and so may be a component of cellular signaling which induces stress tolerance in plants.

Shkolnik also identified an additional metabolite that increases stress tolerance likely by functioning as an antioxidant.

Shkolnik’s thesis readers were Pete Gaines and Michael Graves, both of the Department of Biological Sciences, UMass Lowell.

Arabidopsis thaliana.jpg
Visual phenotype of Arabidopsis thaliana wild-type (WT) and the stress-tolerant oxt1 lines grown under normal and oxidative stress conditions. Left two plates contain normal, non-oxidative stress agar medium (½ MS).  Right two plates contain chemical inhibitors to induce oxidative stress (AT/BSO).  Lower two plates contain a purine (0.4 mM adenosine).  Each plate contains wild-type plants on the upper half and oxt1 on the lower half.  Plants were grown for 21 days under standard conditions.

On November 15, 2011, Andrew Hoell successfully defended his PhD dissertation, entitled “Aspects of Oceanic Forcing of Drought over Southwest Asia and the United States.”  His work was conducted in the department of Environmental, Earth and Atmospheric Sciences, and his PhD will be awarded by UMass Lowell’s School of Marine Sciences. Hoell’s work was advised by Prof. Matthew Barlow, and supported with funding from NSF and NOAA.

Hoell focused on understanding the exceptionally severe drought that affected much of the Northern Hemisphere mid-latitudes during 1998–2002, with maxima over Southwest Asia and the United States. Previous research had suggested that the oceans played an important role in the hemispheric drought.

In his research, Hoell examined the regional and hemispheric circulation response to tropical Indo-west Pacific Ocean convection, for both Southwest Asia and the United States. He studied the relative importance of individual sea surface temperature areas in causing precipitation in the United States.

Hoell developed a linear regression model, and demonstrated good correspondence between the model and measured precipitation in the Southwest and Southeast United States. But the model was not able to reproduce precipitation variability over the Northwest and Central United States, especially Texas.

Hoell’s thesis readers were Joshua Qian (UMass Lowell), Frank Colby (UMass Lowell), and Ellen Douglas (UMass Boston).

Enhanced Indian Ocean precipitation persisted for almost the entire 2007–2008 season in association with severe drought over Southwest Asia. However, a period of suppressed Indian Ocean precipitation during January 2008 reversed the pattern, resulting in damaging floods in the midst of a season long drought.

Andrew Hoell and Prof. Matthew Barlow share a moment during a classroom conversation.
On September 2, 2011, JiSun Im successfully defended her doctoral dissertation in the Department of Chemistry, entitled “Chemiresistors based on thiol-functionalized gold nanoparticles, metal oxides, and their composites for the detection of toxic chemicals.”

Dr. Im’s research was conducted under the supervision of Professor James Whitten. With funding from the Army Research Laboratory, her work focused on developing chemical sensing materials for the detection of toxic chemicals, including volatile organic compounds, explosives, and nerve agents.

During her five-year graduate career at UMass Lowell, Im spearheaded the development of a portable prototype sensor system, nicknamed the “Mini-Mutt.” This instrument uses nano-particles and electrically conducting polymers to detect and identify chemical vapors. A video story about the Mini-Mutt is presently online at www.uml.edu/research.

Dr. Im has accepted a postdoctoral research position at the Massachusetts Institute of Technology.

Dr. JiSun Im (left) and Dr. James Whitten (Professor and Chair, Department of Chemistry)

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