Theses and Dissertations
This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students.
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Description
The transient receptor potential channel subfamily V member 1 (TRPV1) functions as the heat and capsaicin receptor. It can be activated by heat, protons, pungent chemicals, and a variety of other endogenous mediators of nociception. TRPV1 is a non-selective cation channel consisting of 6 transmembrane domains (S1-S6), with helices S1-S4 forming the sensing domain and the S5-S6 helices forming the pore domain. Understanding the TRPV1 channel is imperative due to its relation to a variety of human diseases, including cancer, type II diabetes, hyper and hypothermia, and inflammatory disorders of the airways and bladder. Although TRPV1 is the best-studied thermosensitive-TRP channels of all the 28 family members, the molecular underpinning and the contributions of the human TRPV1 pore domain in thermo-sensing remains elusive. Recently, the human TRPV1 sensing domain was found to contribute to heat activation. It was found to undergo a non-denaturing temperature-dependent conformational change. This finding triggered interest in studying the function and the role of the human TRPV1 pore domain in the heat activation process. Specifically, to identify whether heat activation is intrinsic to the pore domain. This thesis paper explores and optimizes the purification protocol of the human TRPV1 pore domain through three different methods. The first method was using a denaturant, the second method was increasing the length of the histidine tags through Q5 insertion, and the third method was incorporating the protein construct into nanodiscs. In addition to the above three methods, size exclusion chromatography and ion-exchange chromatography were utilized after thrombin cleavage to separate the human TRPV1 pore domain from the cleaved MBP deca-histidine tags as well as the impurities.
ContributorsChang, Yu Tzu (Author) / Van Horn, Wade (Thesis director) / Wang, Xu (Committee member) / Cherry, Brian (Committee member) / School of Molecular Sciences (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-12
Description
The entirely soft-tissue anatomy of the octopus arm provides the animal with a large amount of freedom of movement, while still allowing the specimen to support itself despite the lack of a skeletal system. This is made possible through the use of various muscle layers within the octopus arm, which act as muscular hydrostats. Magnetic Resonance imaging of the octopus arm was employed to view the muscle layers within the octopus arm and observe trends and differences in these layers at the proximal, middle, and distal portions of the arms. A total of 39 arms from 6 specimens were imaged to give 112 total imaged sections (38 proximal, 37 middle, 37 distal). Significant increases in both the internal longitudinal muscle layer and the nervous core were found between the proximal and middle, proximal and distal, and middle and distal sections of the arms. This could reflect selection for these structures distally in the octopus arm for predator or other noxious stimuli avoidance. A significant decrease in the transverse muscle layer was found in the middle and distal sections of the arms. This could reflect selection for elongation in the proximal portion of the octopus arm or could be the result of selection for the internal longitudinal muscle layer and nervous core distally. Previous studies on Octopus vulgaris showed a preference for using the proximal arms in the pushing movement of crawling and a preference for using the anterior arms in exploring behaviors (Levy et al., 2015 and Byrne et al., 2006). Differences between the anterior and posterior arms for the transverse muscle layer, internal longitudinal muscle layer, and the nervous core were insignificant, reflecting a lack of structure-function relationships. This could also be due to a low sample size. Differences between the left and right arms for the transverse muscle layer, internal longitudinal muscle layer, and the nervous core were insignificant, supporting previous evidence that left versus right eye and arm preferences in octopus are not population-wide, but individual. Some slight trends can be found for individual arms, but the sample size was too small to make definitive statements regarding differences among specific arms.
ContributorsRoy, Cayla C (Author) / Fisher, Rebecca (Thesis director) / Marvi, Hamid (Committee member) / Cherry, Brian (Committee member) / Watts College of Public Service & Community Solut (Contributor) / School of Life Sciences (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05