Physics Commons^™

Toward Improving Understanding Of The Structure And Biophysics Of Glycosaminoglycans, Elizabeth K. Whitmore

Electronic Theses and Dissertations

Glycosaminoglycans (GAGs) are the linear carbohydrate components of proteoglycans (PGs) that mediate PG bioactivities, including signal transduction, tissue morphogenesis, and matrix assembly. To understand GAG function, it is important to understand GAG structure and biophysics at atomic resolution. This is a challenge for existing experimental and computational methods because GAGs are heterogeneous, conformationally complex, and polydisperse, containing up to 200 monosaccharides. Molecular dynamics (MD) simulations come close to overcoming this challenge but are only feasible for short GAG polymers. To address this problem, we developed an algorithm that applies conformations from unbiased all-atom explicit-solvent MD simulations of short GAG polymers …

Live Cell Super-Resolution Microscopy Quanitifies An Interaction Between Influenza Hemagglutinin And Phosphatidylinositol 4,5-Bisphosphate, Jaqulin N. Wallace

Electronic Theses and Dissertations

Influenza virus, colloquially known as the flu, is an acute respiratory disease that infects several millions of individuals each year in the U.S. and kills tens of thousands of those infected. Yearly viral vaccines are widely available, however, due to the virus’s high mutation rate, their efficacy varies greatly. Due to the variability in vaccine efficiency against seasonal influenza, and the potential for even more pathogenic versions of influenza to emerge at any time, there is a high demand for a universal treatment option.

Influenza virus hijacks a variety of host cell components in order to replicate. The glycoprotein hemagglutinin …

Biophysical And Stable Isotopic Profiles Of The Salmon Louse Lepeophtheirus Salmonis (Krøyer, 1837), Emma Taccardi

Electronic Theses and Dissertations

The salmon louse Lepeophtheirus salmonis is a parasitic copepod that infects wild and farmed salmonids throughout the northern hemisphere. L. salmonis represents the largest economic hurdle of the Atlantic salmon (Salmo salar) industry, with an estimated annual cost of nearly $1 billion globally due to production losses and anti-parasitic control measures. Salmon farming in Maine has existed for decades and is a critical economic driver, yet the region is underrepresented in global sea lice research. The aim of this work was to examine parasites in the context of animal trophic transfer and characterize physiological condition by quantifying the …

Quantification Of Interactions Between Influenza Hemagglutinin And Host Cell Phosphoinositides By Super-Resolution Microscopy, Matthew T. Parent

Electronic Theses and Dissertations

The influenza viral membrane protein hemagglutinin (HA) forms dense nanoscale clusters on host cell plasma membranes (PM), but the mechanisms that direct HA clustering are not well understood. Previous studies have observed HA associated with actin rich regions of the PM, but there are no known direct interactions between HA and actin. Phosphatidylinositol 4,5-biphosphate (PIP2) is a signaling lipid in the PM which can regulate the actin cytoskeleton, and actin comets initiated by PIP2 are known to be exploited by HA to reach the PM of infected cells. PIP2 is also used by other viruses, such as HIV and Ebola, …

Basic Vision Research With Clinical Applications And Science Education Assessments, Andrew Wilson

Electronic Theses and Dissertations

Visual Acuity (VA) examinations are one of the most commonly conducted medical assessment throughout the world. Recent advances in computer technology allows for new forms of visual assessment to be conducted. In Part I of this thesis I demonstrate the capability of an automated computer program named VISION to assess human visual acuities. Different color combinations of an object against a background emitted from a computer screen are used to examine a variety of human color vision acuities. Results indicated a large difference in acuity scores between human subjects tested with these different color combinations. A single human subject exhibits …

A Study In Cross-Beam Polarization Fluorescence Photoactivation Localization Microscopy On Dendra2-Hemagluttinin In Fixed Nih3t3 Cells, Matthew M. Valles

Electronic Theses and Dissertations

Fluorescence microscopy is popular for its noninvasive properties and its use in imaging multiple species, simultaneously. Furthermore, superresolution fluorescence microscopy (SRFLM) utilizes photoswitchable proteins to improve the lateral resolution of conventional fluorescence microscopy by an order of magnitude. There is little work conducted on the study of excitation laser polarizations and their effect on the number of localizations as well as the brightness of molecules. This thesis attempts to study the effect of excitation wavelength polarization on the number of localizations and the brightness of molecules by comparing two orientations of circularly-polarized, excitation lasers. The first type of orientation involves …

Investigating High Speed Localization Microscopy Through Experimental Methods, Data Processing Methods, And Applications Of Localization Microscopy To Biological Questions, Andrew J. Nelson

Electronic Theses and Dissertations

Fluorescence Photoactivation Localization Microscopy(FPALM) and other super resolution localization microscopy techniques can resolve structures with nanoscale resolution. Unlike techniques of electron microscopy, they are also compatible with live cell and live animal studies, making FPALM and related techniques ideal for answering questions about the dynamic nature of molecular biology in living systems. Many processes in biology occur on rapid sub second time scales requiring the imaging technique to be capable of resolving these processes not just with a high enough spatial resolution, but with an appropriate temporal resolution. To that end, this Dissertation in part investigates high speed FPALM as …

Radon In Ground Water: A Study Of The Measurement And Release Of Waterborne Radon And Modeling Of Radon Variation In Bedrock Wells, Vincente E. Guiseppe

Electronic Theses and Dissertations

Naturally occurring radon gas (222Rn) exists in ground water and drinking water supplies. Research involving radon in ground water requires the ability to accurately measure radon in water. In the absence of a national program, an intercomparison study of laboratories was sanctioned by the State of Maine. The University of Maine research laboratory supplied each laboratory with water samples of various radon concentrations, served as the reference laboratory, and analyzed the results presented here. The external review of the University of Maine laboratory and agreement with some of the participating laboratories verifies its accuracy in measuring radon in water. A …