Evolution of Xenopus Tropicalis MC2R: Expression and Activation

The structure and functional relationship between the melanocortin-2 receptor (MC2R) and adrenocorticotropic hormone (ACTH) is the most complex of the melanocortin gene family. Prior studies had been done on amniote tetrapod MC2Rs (e.g., mammals); this study analyzed the expression and activation of MC2R by an anamniote tetrapod, Xenopus tropicalis (xtMC2R). An immunofluorescence approach, done on the expression of xtMC2R in Chinese Hamster Ovary cells (CHO cells), indicated that the trafficking of xtMC2R to the plasma membrane required co-expression with a tetrapod MRAP1(melanocortin-1 receptor accessory protein). A cAMP-reporter assay was used to show that xtMC2R can activated by human ACTH(1-24, but not by α-MSH. These two properties are also observed for human MC2R, and are common for tetrapod MC2Rs in general. Alanine-substitution analogs of hACTH(1-24) were used to deduce a possible mechanism for the activation of xtMC2R. These studies showed that alanine substitutions to the HFRW motif in hACTH(1-24) eliminated activation of the receptor. Furthermore, the alanine-substitution analysis revealed that positions 15 and 16 in the KKRRP motif are more important for the activation of xtMC2R than positions, 17 through 19. Finally, the alanine-substitution assays coupled with analysis of internally truncated analogs of the GKPVG motif resulted in decreased or complete elimination of xtMC2R activation. These data were used to construct a proposed three step model for the activation of MC2R. The final goal of this thesis was to identify the region of the receptor involved in the docking of the KKRRP motif of ACTH. Based on a model of MC2R, these experiments used alanine substitution site-directed mutagenesis to analyze the transmembrane 4 (TM4), extracellular loop 2 (EL2), and transmembrane 5 (TM5) region of xtMC2R. These experiments revealed that the following mutations had the greatest effect on the sensitivity (EC50 value) of xtMC2R: I/A175, F/A178, and I/A184. These results were compared to site-directed mutagenesis studies done on human and rainbow trout MC2Rs. Collectively, these analyses revealed that all three MC2Rs have docking sites for the KKRRP motif of ACTH that are similar in general location, and mostly similar in 3-dimensional structure, but that are not identical. The evolutionary implications of these observations are discussed

Study Away with SFA: The Opportunity for Accessible Cross Cultural Learning

Study Away was proposed by our professor as an accessible alternative to traditional study abroad programs. Accessible because it is more affordable and it opens up this cross cultural opportunity to students who may be undocumented. We traveled the country for five weeks in a Mercedes sprinter van exploring places such as Palo Duro Canyon State Park, Albuquerque, the Great Lakes, New York City, the Appalachian Mountains, and New Orleans to name a few. Throughout, we engaged in critical conversations and opportunities for self-growth. This presentation will share our perspectives regarding study away as it compares to study abroad

Synthesis of stereochemically-biased spiropyrans by microwave-promoted, one-pot alkylation-condensation

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordA microwave-assisted, two-step, one-pot synthesis of spiropyrans has been developed. This process was used to synthesise a range of sterically-congested spiropyrans from readily available precursors, employing environmentally benign solvents. The unusual substituent pattern possessed by these structures has been shown to influence the stereoselectivity of spiropyran ring-closure

Developing an Intranet Resource to Compile and Disseminate Animal Welfare Information for Library Liaisons

The project’s goal is to create and maintain a comprehensive database containing subject-specific information. The information is used to serve as a key resource for grant support and enhance the ethical treatment of animals. A library Intranet allows librarian liaisons to conduct database searches and prepare customized reports for campus researchers. EndNote software is utilized, due to a campus site license

Phytoplankton in the Damariscotta River Estuary

This research project examined the distribution of phytoplankton in the Damariscotta River, as well as environmental factors, such as nutrients, light, and physical conditions, in order to assess the estuary’s ability to sustain additional farms

Mechanical Dispersion of a Semi-Solid Binder in a Wet Granulation Process

High viscosity surfactant pastes have recently gained popularity in the production of high efficiency laundry detergents due to their ability to increase surfactant loading in granules. When using high viscosity semi-solid binders a unique challenge is presented because it forces granules to be formed primarily by mechanical dispersion; a relatively poorly understood process. Developing mechanistic models of this process will enhance knowledge of mechanical dispersion processes and improve process development for granules produced using this method. Experiments to determine the effect of three process parameters; paste temperature, impeller RPM, and time were carried out in a lab-scale granulator. Binder temperature was varied between 40-60 degrees Celsius to cover paste temperatures from solidification to decomposition. Impeller RPM was varied between 600 -1200 RPM to capture the full range of potential industrial impeller velocities. Mixing time was varied from zero to ten seconds; the time scale of the industrial process. The particle size distribution for the process was determined to rely primarily on mixing time especially at impeller speeds above 900 RPM where fully developed annular flow occurs in the mixer. The Sauter mean diameter of particles was determined to be linearly related to mixing RPM, while temperature was shown to have little effect on the Sauter mean diameter. Experimental data was in relatively good agreement with values predicted by an existing breakage simulation, but could be improved upon. These conclusions will be used in developing a breakage kernel for the process based on material properties