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Black Widows on an Urban Heat Island: Understanding Physiological Responses to Global Change

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The steroid hormone 20-hydroxyecdysone (20E) controls molting in arthropods. The timing of 20E production, and subsequent developmental transitions, is regulated by a variety of factors including nutrition and photoperiod. Environmental factors, such as temperature, play a critical role in regulation

The steroid hormone 20-hydroxyecdysone (20E) controls molting in arthropods. The timing of 20E production, and subsequent developmental transitions, is regulated by a variety of factors including nutrition and photoperiod. Environmental factors, such as temperature, play a critical role in regulation as well. The increasing prevalence of urban heat islands (UHI), or areas with elevated temperature due to retained heat by built structures, in response to rapid urbanization has made it critical to understand how organisms respond to elevating global temperatures. Some arthropods, such as the Western black widow spider, Latrodectus hesperus, appear to thrive under UHI conditions, but the physiological mechanism underlying their success has not been explored. Recently, we have shown that L. hesperus, a troublesome urban pest, in fact responds to urban heat island conditions in Phoenix, AZ with delayed development, reduced body mass, and increased mortality. Here we look at the relationship between 20E levels and development in spiderlings reared under desert (27ᵒC), intermediate (30ᵒC), and urban (33ᵒC) temperatures, filling a noticeable gap in not only understanding ecdysteroids’ role in arachnid development but how incremental changes in environmental conditions affect the regulation of this process. Developmental progression and hemolymph 20E titers were recorded for several families of spiders collected from across the urban Phoenix area with data spanning from day 55 to 75 of development, focusing on the second developmental instar. We found that 33°C, but not 30°C, led to 1) a significantly higher production of 20E throughout development, 2) a reduced and delayed molt-inducing 20E peak, and 3) noticeable reductions in growth rate and mass. At 30°C, a variable response is seen in molt timing, without the negative impacts on size and mortality as seen at 33°C, suggesting that at UHI temperatures, the optimal developmental temperature threshold has been surpassed.

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2019-05

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Analysis of Retinoid X Receptor (RXR) Homodimerization Driven by RXR Ligands Using Yeast Two-Hybrid

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Bexarotene (Targretin®) is an FDA approved drug used to treat cutaneous T-cell lymphoma (CTCL), as well as off-label treatments for various cancers and neurodegenerative diseases. Previous research has indicated that bexarotene has a specific affinity for retinoid X receptors

Bexarotene (Targretin®) is an FDA approved drug used to treat cutaneous T-cell lymphoma (CTCL), as well as off-label treatments for various cancers and neurodegenerative diseases. Previous research has indicated that bexarotene has a specific affinity for retinoid X receptors (RXR), which allows bexarotene to act as a ligand-activated-transcription factor and in return control cell differentiation and proliferation. Bexarotene targets RXR homodimerization to drive transcription of tumor suppressing genes; however, adverse reactions occur simultaneously when bound to other nuclear receptors. In this study, we used novel bexarotene analogs throughout 5 iterations synthesized in the laboratory of Dr. Wagner to test for their potency and ability to bind RXR. The aim of our study is to quantitatively measure RXR homodimerization driven by bexarotene analogs using a yeast two-hybrid system. Our results suggests there to be several compounds with higher protein activity than bexarotene, particularly in generations 3.0 and 5.0. This higher affinity for RXR homodimers may help scientists identify a compound that will minimize adverse effects and toxicity of bexarotene and serve as a better cancer treatment alternative.

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2015-05

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Characterization of Second and Third Generation, Novel RXR Selction Agonists for the Treatment of Cutaneous T-Cell Lymphoma

Description

Bexarotene is a commercially produced drug commonly known as Targetin presecribed to treat cutaneous T-cell lymphoma (CTCL). Bex mimics the actions of natural 9-cis retinoic acid in the body, which are derived from Vitamin A in the diet and boost

Bexarotene is a commercially produced drug commonly known as Targetin presecribed to treat cutaneous T-cell lymphoma (CTCL). Bex mimics the actions of natural 9-cis retinoic acid in the body, which are derived from Vitamin A in the diet and boost the immune system. Bex has been shown to be effective in the treatment of multiple types of cancer, including lung cancer. However, the disadvantages of using Bex include increased instances of hypothyroidism and excessive concentrations of blood triglycerides. If an analog of Bex can be developed which retains high affinity RXR binding similar to the 9-cis retinoic acid while exhibiting less interference for heterodimerization pathways, it would be of great clinical significance in improving the quality of life for patients with CTCL. This thesis will detail the biological profiling of additional novel (Generation Two) analogs, which are currently in submission for publication, as well as that of Generation Three analogs. The results from these studies reveal that specific alterations in the core structure of the Bex "parent" compound structure can have dramatic effects in modifying the biological activity of RXR agonists.

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2012-05

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Early Childhood Environment Influence on Personality and Life Outcomes

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This research study evaluated the effects of early childhood environment and the influence parenting style has on the life outcomes among university students who varied in psychopathic traits; demonstrating evidence to show students who scored highly in measures of psychopathy

This research study evaluated the effects of early childhood environment and the influence parenting style has on the life outcomes among university students who varied in psychopathic traits; demonstrating evidence to show students who scored highly in measures of psychopathy used antisocial success seeking strategies to attain common life goals. This study examined the prospect of parenting styles and childhood environment as possible influences on important differences between psychopaths who become involved in the American legal system and those who do not. These differences were identified by asking participants to describe how often they engage in success seeking behaviors by using either prosocial or antisocial methods. Results were based on a hierarchical regression analysis and illustrated psychopathy as a significant predictor for utilizing antisocial success seeking strategic behavior. Such strategies include lying on job applications, accepting credit for the work of others, or winning a competition by cheating. In contrast, our Model determined that parental influence based on measures of paternal and maternal warmth, financial support, and physical and emotional abuse, did not significantly predict either prosocial success seeking strategies or antisocial success seeking strategies. Possible trends relating to childhood environment were identified but were undoubtedly restricted due to the evidently small sample size in this study. Conclusions into this investigation affirm the necessity for additional research into this view of psychopathy and how some psychopaths may be able to utilize their unique traits to their advantage.

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2020-05

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Nuclear Forensics: An In-Depth Analysis of Capabilities, Improvements, and Limitations

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Beginning in the early 1990s, nuclear forensic science is a relatively young field that focuses on “re-establishing the history of nuclear material of unknown origin” (Mayer, et al. 2010, p. 1). Specifically, investigators compare these unknown materials, pre-detonation in this

Beginning in the early 1990s, nuclear forensic science is a relatively young field that focuses on “re-establishing the history of nuclear material of unknown origin” (Mayer, et al. 2010, p. 1). Specifically, investigators compare these unknown materials, pre-detonation in this case, based on their characteristics and process history (Mayer, et al. 2010, p. 1). In 2010, the Committee of Nuclear Forensics made ten recommendations on the procedures that could lead to improvement in investigation methods. In particular, this paper discusses Recommendation 6: “The nuclear forensics community should develop and adhere to standards and procedures that are rooted in the applicable underlying principles that have been recommended for modern forensic science, including calibration using reference standards; cross-comparison with other methods; inter-laboratory comparisons; and identification, propagation, and characterization of uncertainties'' (Committee of Nuclear Forensics, 2010, p. 11). The main objective of this paper is to compile a literature review to determine how this recommendation was followed, if at all, and produce a list of suggestions that could complement any effort towards the improvement of the field. Out of the methods recommended, that which has fostered the most growth has been cross-comparison. For example, the need for human supervision has decreased, which has decreased the need for human error (Reading, et al., 2017, p. 6013). However, areas that would benefit from development are increasing the number of disciplines in the field (Croudace, et al., 2016, p. 128). These conclusions provided the basis for improvements to other existing studies like DNA and fingerprinting.

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2021-12