Barrett, The Honors College Thesis/Creative Project Collection
Barrett, The Honors College at Arizona State University proudly showcases the work of undergraduate honors students by sharing this collection exclusively with the ASU community.
Barrett accepts high performing, academically engaged undergraduate students and works with them in collaboration with all of the other academic units at Arizona State University. All Barrett students complete a thesis or creative project which is an opportunity to explore an intellectual interest and produce an original piece of scholarly research. The thesis or creative project is supervised and defended in front of a faculty committee. Students are able to engage with professors who are nationally recognized in their fields and committed to working with honors students. Completing a Barrett thesis or creative project is an opportunity for undergraduate honors students to contribute to the ASU academic community in a meaningful way.
Displaying 1 - 3 of 3
Description
I am evaluating the genomic basis of a model of heat tolerance in which organisms succumb to warming when their demand for oxygen exceeds their supply. This model predicts that tolerance of hypoxia should correlate genetically with tolerance of heat. To evaluate this prediction, I tested heat and hypoxia tolerance in several genetic lines of Drosophila melanogaster. I hypothesized that genotypes that can fly better at high temperatures are also able to fly well at hypoxia. Genotypes from the Drosophila Genetic Reference Panel (DGRP) were assessed for flight at hypoxia and normal temperature (12% O2 and 25°C) as well as normoxia and high temperature (21% O2 and 39°C). After testing 66 lines from the DGRP, the oxygen- and capacity-limited thermal tolerance theory is supported; hypoxia-resistant lines are more likely to be heat-resistant. This supports previous research, which suggested an interaction between the tolerance of the two environmental variables. I used this data to perform a genome-wide association study to find specific single-nucleotide polymorphisms associated with heat tolerance and hypoxia tolerance but found no specific genomic markers. Understanding factors that limit an organism’s stress tolerance as well as the regions of the genome that dictate this phenotype should enable us to predict how organisms may respond to the growing threat of climate change.
ContributorsFredette-Roman, Jacob Daniel (Author) / Angilletta, Michael (Thesis director) / VandenBrooks, John (Committee member) / Youngblood, Jacob (Committee member) / School of Life Sciences (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Hypoxia-responses help coordinate the growth of oxygen-transporting tissues with the growth of other tissues during development. In Drosophila, hypoxia strongly affects development with flies being reared in a low oxygen environment showing smaller body sizes and diminished tracheal growth. The primary regulator of cellular hypoxic-responses is the hypoxia-inducible factor (HIF), and under normoxic conditions, HIF-alpha is hydroxylated by prolyl hydroxylase domain (PHD) on a proline residue inside the alpha leading to the proteins proteasome degradation downstream. However, in response to reduced oxygen, cells accumulate HIF- alpha, which then joins with the constituent HIF-beta in the cytosol, forming a HIF- alpha/beta heterodimer. Which, in turn, enters the nucleus and binds to hypoxic response elements, activating the hypoxic response genes. Hyperoxia has recently been shown to stimulates metabolic rates only at the last stage Drosophila's larval development (L3), indicating oxygen limitation occurs towards the end of development. Green fluorescent protein (GFP) was added to the oxygen-dependent domain of Drosophila HIF- Alpha (Sima) and a monomeric red fluorescent protein with a nuclear localization signal (mRFP-nls) was added to a protein under the same ubiquitin-69E promoter but is not affected by changing O2 levels. Using a Leica SP5 AOBS Spectral Confocal, third instar larvae were analyzed at the cellular level with attention focused on HIF- signaling in the central nervous system (CNS). L3 Drosophila were divided into groups of 0-12h, 12-24h, 24-48h, and 48-60h corresponding to their development. In each group, flies were either treated for 10-12 hours in 5% O2 or were left normoxic before fixation. What was overwhelmingly found is that HIF-signaling was most prominent during their early development (0-12h), with a significant decline as age increased (P=<0.001). There was also an observed hypoxic effect as animals treated in lower oxygen concentrations had significantly higher HIF signaling (P=<0.001). However, this effect still declines as larvae continued developing. This data supports the idea that internal hypoxia does not become severe during late third instar growth but may occur during the actual molt of the flies.
ContributorsWerkhoven, Simon (Author) / Harrison, Jon (Thesis director) / VandenBrooks, John (Committee member) / School of Molecular Sciences (Contributor) / School of International Letters and Cultures (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
I am evaluating a notion that stems from a controversial hypothesis of heat stress. The oxygen- and capacity-limited thermal tolerance (OCLTT) hypothesis predicts a positive correlation between the tolerance of hypoxia and the tolerance of heat in animals, where the notion claims that these animals must be metabolically active. To evaluate this notion, I tested heat coma recovery in several genetic lines of Drosophila melanogaster and compared it to data collected in prior studies. I hypothesized that the correlations between hypoxia tolerance and heat coma recovery would be similar to correlations found in Teague et al. (2017) and Fredette-Roman et al. (2020). After testing 65 lines from the Drosophila Genetic Reference Panel (DGRP), the notion was supported and provided evidence for the validity of OCLTT. Additional work is needed to enhance our understanding of the limitations of heat tolerance and doing such will generate more accurate models and predictions on how animals will respond to climate change.
ContributorsBabarinde, Oluwatosin Abimbola (Author) / Angilletta, Michael (Thesis director) / VandenBrooks, John (Committee member) / Youngblood, Jacob (Committee member) / School of Life Sciences (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05