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- Creators: Angilletta, Michael
- Creators: School of Molecular Sciences
- Creators: Bond, Angela
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
Description
We examined the evolutionary morphological responses of Drosophila melanogaster that had evolved at constant cold (16°), constant hot (25°C), and fluctuating (16° and 25°C). Flies that were exposed to the constant low mean temperature developed larger thorax, wing, and cell sizes than those exposed to constant high mean temperatures. Males and females both responded similarly to thermal treatments in average wing and cell size. The resulting cell area for a given wing size in thermal fluctuating populations remains unclear and remains a subject for future research.
ContributorsAdrian, Gregory John (Author) / Angilletta, Michael (Thesis director) / Harrison, Jon (Committee member) / Rusch, Travis (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
Animals are thought to die at high temperatures because proteins and cell membranes lose their structural integrity. Alternatively, a newer hypothesis (the oxygen and capacity limitation of thermal tolerance, or OCLTT) states that death occurs because oxygen supply becomes limited at high temperatures. Consequently, animals exposed to hypoxia are more sensitive to heating than those exposed to normoxia or hyperoxia. We hypothesized that animals raised in hypoxia would acclimate to the low oxygen supply, thereby making them less sensitive to heating. Such acclimation would be expressed as greater heat tolerance and better flight performance in individuals raised at lower oxygen concentrations. We raised flies (Drosophila melanogaster) from eggs to adults under oxygen concentrations ranging from 10% to 31% and measured two aspects of thermal tolerance: 1) the time required for flies to lose motor function at 39.5°C at normoxia (21%), referred to as knock-down time, and 2) flight performance at 37°, 39°, or 41°C and 12%, 21%, or 31% oxygen. Contrary to our prediction, flies from all treatments had the same knock-down time. However, flight performance at hypoxia was greatest for flies raised in hypoxia, but flight performance at normoxia and hyperoxia was greatest for flies raised at hyperoxia. Thus, flight performance acclimated to oxygen supply during development, but heat tolerance did not. Our data does not support the OCLTT hypothesis, but instead supports the beneficial acclimation hypothesis, which proposes that acclimation improves the function of an organism during environmental change.
ContributorsShiehzadegan, Shayan (Co-author) / VadenBrooks, John (Co-author) / Le, Jackie (Co-author) / Smith, Colton (Co-author) / Shiehzadegan, Shima (Co-author) / Angilletta, Michael (Co-author, Thesis director) / VandenBrooks, John (Committee member) / Klok, C. J. (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
The goal of this project was to design and create a genetic construct that would allow for <br/>tumor growth to be induced in the center of the wing imaginal disc of Drosophila larvae, the <br/>R85E08 domain, using a heat shock. The resulting transgene would be combined with other <br/>transgenes in a single fly that would allow for simultaneous expression of the oncogene and, in <br/>the surrounding cells, other genes of interest. This system would help establish Drosophila as a <br/>more versatile and reliable model organism for cancer research. Furthermore, pilot studies were <br/>performed, using elements of the final proposed system, to determine if tumor growth is possible <br/>in the center of the disc, which oncogene produces the best results, and if oncogene expression <br/>induced later in development causes tumor growth. Three different candidate genes were <br/>investigated: RasV12, PvrACT, and Avli.
ContributorsSt Peter, John Daniel (Author) / Harris, Rob (Thesis director) / Varsani, Arvind (Committee member) / School of Molecular Sciences (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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
The non-native mosquito Aedes aegypti has become a common nuisance in Maricopa county. Associated with human settlement, Ae. aegypti is known to reproduce in standing water sources both indoors and outdoors, within vessels such as tires, flowerpots, and neglected swimming pools (Jansen & Beebe, 2010). Ae. aegypti and the related Ae. albopictus are the primary vectors of the arboviral diseases chikungunya, Zika, yellow fever and dengue. Ae. aegypti tends to blood feed multiple times per gonotrophic cycle (cycle of feeding and egg laying) which, alongside a preference for human blood and close association with human habitation, contributes to an increased risk of Ae. aegypti borne virus transmission (Scott & Takken, 2012). Between 2010-2017, 153 travel-associated cases of dengue were reported in the whole of Arizona (Rivera et al., 2020); while there have been no documented locally transmitted cases of Aedes borne diseases in Maricopa county, there are no apparent reasons why local transmission can’t occur in the future via local Aedes aegypti mosquitoes infected after feeding from travelling viremic hosts. Incidents of local dengue transmission in New York (Rivera et al., 2020) and Barcelona (European Center for Disease Control [ECDC], 2019) suggest that outbreaks of Aedes borne arbovirus’ can occur in regions more temperate than the current endemic range of Aedes borne diseases. Further, while the fact that Ae. aegypti eggs have a high mortality rate when exposed to cold temperatures limits the ability for Ae aegypti to establish stable breeding populations in temperate climates (Thomas, Obermayr, Fischer, Kreyling, & Beierkuhnlein, 2012), global increases in temperature will expand the possible ranges of Ae aegypti and Aedes borne diseases.
ContributorsHon, Ruiheng (Author) / Paaijmans, Krijn (Thesis director) / Bond, Angela (Committee member) / Angilletta, Michael (Committee member) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05