Matching Items (237)
Grasshoppers Regulate N: P Stoichiometric Homeostasis by Changing Phosphorus Contents in Their Frass
Description
Nitrogen (N) and phosphorus (P) are important limiting nutrients for plant production and consumer performance in a variety of ecosystems. As a result, the N:P stoichiometry of herbivores has received increased attention in ecology. However, the mechanisms by which herbivores maintain N:P stoichiometric homeostasis are poorly understood. Here, using a field manipulation experiment we show that the grasshopper Oedaleus asiaticus maintains strong N:P stoichiometric homeostasis regardless of whether grasshoppers were reared at low or high density. Grasshoppers maintained homeostasis by increasing P excretion when eating plants with higher P contents. However, while grasshoppers also maintained constant body N contents, we found no changes in N excretion in response to changing plant N content over the range measured. These results suggest that O. asiaticus maintains P homeostasis primarily by changing P absorption and excretion rates, but that other mechanisms may be more important for regulating N homeostasis. Our findings improve our understanding of consumer-driven P recycling and may help in understanding the factors affecting plant-herbivore interactions and ecosystem processes in grasslands.
ContributorsZhang, Zijia (Author) / Elser, James (Author) / Cease, Arianne (Author) / Zhang, Ximei (Author) / Yu, Qiang (Author) / Han, Xingguo (Author) / Zhang, Guangming (Author) / College of Liberal Arts and Sciences (Contributor) / School of Life Sciences (Contributor) / Julie Ann Wrigley Global Institute of Sustainability (Contributor) / School of Sustainability (Contributor)
Created2014-08-04
Description
Viral protein U (Vpu) is a type-III integral membrane protein encoded by Human Immunodeficiency Virus-1 (HIV- 1). It is expressed in infected host cells and plays several roles in viral progeny escape from infected cells, including down-regulation of CD4 receptors. But key structure/function questions remain regarding the mechanisms by which the Vpu protein contributes to HIV-1 pathogenesis. Here we describe expression of Vpu in bacteria, its purification and characterization. We report the successful expression of PelB-Vpu in Escherichia coli using the leader peptide pectate lyase B (PelB) from Erwinia carotovora. The protein was detergent extractable and could be isolated in a very pure form. We demonstrate that the PelB signal peptide successfully targets Vpu to the cell membranes and inserts it as a type I membrane protein. PelB-Vpu was biophysically characterized by circular dichroism and dynamic light scattering experiments and was shown to be an excellent candidate for elucidating structural models.
ContributorsDeb, Arpan (Author) / Johnson, William (Author) / Kline, Alexander (Author) / Scott, Boston (Author) / Meador, Lydia (Author) / Srinivas, Dustin (Author) / Martin Garcia, Jose Manuel (Author) / Dorner, Katerina (Author) / Borges, Chad (Author) / Misra, Rajeev (Author) / Hogue, Brenda (Author) / Fromme, Petra (Author) / Mor, Tsafrir (Author) / ASU Biodesign Center Immunotherapy, Vaccines and Virotherapy (Contributor) / College of Liberal Arts and Sciences (Contributor) / School of Life Sciences (Contributor) / Biodesign Institute (Contributor) / School of Molecular Sciences (Contributor) / Applied Structural Discovery (Contributor) / Personalized Diagnostics (Contributor)
Created2017-02-22
Description
A large fraction of the world grasslands and savannas are undergoing a rapid shift from herbaceous to woody-plant dominance. This land-cover change is expected to lead to a loss in livestock production (LP), but the impacts of woody-plant encroachment on this crucial ecosystem service have not been assessed. We evaluate how tree cover (TC) has affected LP at large spatial scales in rangelands of contrasting social–economic characteristics in the United States and Argentina. Our models indicate that in areas of high productivity, a 1% increase in TC results in a reduction in LP ranging from 0.6 to 1.6 reproductive cows (Rc) per km[superscript 2]. Mean LP in the United States is 27 Rc per km[superscript 2], so a 1% increase in TC results in a 2.5% decrease in mean LP. This effect is large considering that woody-plant cover has been described as increasing at 0.5% to 2% per y. On the contrary, in areas of low productivity, increased TC had a positive effect on LP. Our results also show that ecological factors account for a larger fraction of LP variability in Argentinean than in US rangelands. Differences in the relative importance of ecological versus nonecological drivers of LP in Argentina and the United States suggest that the valuation of ecosystem services between these two rangelands might be different. Current management strategies in Argentina are likely designed to maximize LP for various reasons we are unable to explore in this effort, whereas land managers in the United States may be optimizing multiple ecosystem services, including conservation or recreation, alongside LP.
ContributorsAnadon, Jose Daniel (Author) / Sala, Osvaldo (Author) / Turner II, B. L. (Author) / Bennett, Elena M. (Author) / College of Liberal Arts and Sciences (Contributor) / School of Life Sciences (Contributor) / Julie Ann Wrigley Global Institute of Sustainability (Contributor) / School of Sustainability (Contributor) / School of Geographical Sciences and Urban Planning (Contributor)
Created2014-09-02
Description
We studied the microbial community structure of pilot two-stage membrane biofilm reactors (MBfRs) designed to reduce nitrate (NO[subscript 3]–) and perchlorate (ClO[subscript 4]–) in contaminated groundwater. The groundwater also contained oxygen (O[subscript 2]) and sulfate (SO[2 over 4]–), which became important electron sinks that affected the NO[subscript 3]– and ClO[subscript 4]– removal rates. Using pyrosequencing, we elucidated how important phylotypes of each “primary” microbial group, i.e., denitrifying bacteria (DB), perchlorate-reducing bacteria (PRB), and sulfate-reducing bacteria (SRB), responded to changes in electron-acceptor loading. UniFrac, principal coordinate analysis (PCoA), and diversity analyses documented that the microbial community of biofilms sampled when the MBfRs had a high acceptor loading were phylogenetically distant from and less diverse than the microbial community of biofilm samples with lower acceptor loadings. Diminished acceptor loading led to SO[2 over 4]– reduction in the lag MBfR, which allowed Desulfovibrionales (an SRB) and Thiothrichales (sulfur-oxidizers) to thrive through S cycling. As a result of this cooperative relationship, they competed effectively with DB/PRB phylotypes such as Xanthomonadales and Rhodobacterales. Thus, pyrosequencing illustrated that while DB, PRB, and SRB responded predictably to changes in acceptor loading, a decrease in total acceptor loading led to important shifts within the “primary” groups, the onset of other members (e.g., Thiothrichales), and overall greater diversity.
ContributorsOntiveros-Valencia, Aura (Author) / Tang, Youneng (Author) / Zhao, Heping (Author) / Friese, David (Author) / Overstreet, Ryan (Author) / Smith, Jennifer (Author) / Evans, Patrick (Author) / Rittmann, Bruce (Author) / Krajmalnik-Brown, Rosa (Author) / Biodesign Institute (Contributor) / Swette Center for Environmental Biotechnology (Contributor) / Julie Ann Wrigley Global Institute of Sustainability (Contributor) / School of Sustainability (Contributor)
Created2014-07-01
Description
This thesis project was conducted to create a practical tool to help micro and small local food enterprises identify potential strategies and sources of finance. Currently, many of these enterprises are unable to obtain the financial capital needed to start-up or maintain operations.
Sources and strategies of finance studied and ultimately included in the tool were Loans, Equity, Membership, Crowdfunding, and Grants. The tool designed was a matrix that takes into account various criteria of the business (e.g. business lifecycle, organizational structure, business performance) and generates a financial plan based on these criteria and how they align with the selected business strategies. After strategies are found, stakeholders can search through an institutional database created in conjunction with the matrix tool to find possible institutional providers of financing that relate to the strategy or strategies found.
The tool has shown promise in identifying sources of finance for micro and small local food enterprises in practical use with hypothetical business cases, however further practical use is necessary to provide further input and revise the tool as needed. Ultimately, the tool will likely become fully user-friendly and stakeholders will not need the assistance of another expert helping them to use it. Finally, despite the promise of the tool itself, the fundamental and underlying problem that many of these businesses face (lack of infrastructure and knowledge) still exists, and while this tool can also help capacity-building efforts towards both those seeking and those providing finance, an institutional attitude adjustment towards social and alternative enterprises is necessary in order to further simplify the process of obtaining finance.
Sources and strategies of finance studied and ultimately included in the tool were Loans, Equity, Membership, Crowdfunding, and Grants. The tool designed was a matrix that takes into account various criteria of the business (e.g. business lifecycle, organizational structure, business performance) and generates a financial plan based on these criteria and how they align with the selected business strategies. After strategies are found, stakeholders can search through an institutional database created in conjunction with the matrix tool to find possible institutional providers of financing that relate to the strategy or strategies found.
The tool has shown promise in identifying sources of finance for micro and small local food enterprises in practical use with hypothetical business cases, however further practical use is necessary to provide further input and revise the tool as needed. Ultimately, the tool will likely become fully user-friendly and stakeholders will not need the assistance of another expert helping them to use it. Finally, despite the promise of the tool itself, the fundamental and underlying problem that many of these businesses face (lack of infrastructure and knowledge) still exists, and while this tool can also help capacity-building efforts towards both those seeking and those providing finance, an institutional attitude adjustment towards social and alternative enterprises is necessary in order to further simplify the process of obtaining finance.
ContributorsDwyer, Robert Francis (Author) / Wiek, Arnim (Thesis director) / Forrest, Nigel (Committee member) / Department of Finance (Contributor) / Department of Information Systems (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
This thesis contains three chapters, all of which involve using culturally inclusive education to explore the experiences of religious undergraduate biology students. The first chapter is an essay entitled "Toward Culturally Inclusive Undergraduate Biology Education," which describes a literature review performed with the aim of characterizing the landscape of cultural competence and related terms for biology educators and biology education researchers. This chapter highlights the use of 16 different terms related to cultural competence and presents these terms, their definitions, and highlights their similarities and differences. This chapter also identifies gaps in the cultural competence literature, and presents a set of recommendations to support better culturally inclusive interventions in undergraduate science education. The second chapter, entitled "Different Evolution Acceptance Instruments Lead to Different Research Findings," describes a study in which the source of 30 years of conflicting research on the relationship between evolution acceptance and evolution understanding was determined. The results of this study showed that different instruments used to measure evolution acceptance sometimes lead to different research results and conclusions. The final chapter, entitled "Believing That Evolution is Atheistic is Associated with Poor Evolution Education Outcomes Among Religious College Students," describes a study characterizing definitions of evolution that religious undergraduate biology students may hold, and examines the impact that those definitions of evolution have on multiple outcome variables. In this study, we found that among the most religious students, those who thought evolution is atheistic were less accepting of evolution, less comfortable learning evolution, and perceived greater conflict between their personal religious beliefs and evolution than those who thought evolution is agnostic.
ContributorsDunlop, Hayley Marie (Author) / Brownell, Sara (Thesis director) / Collins, James (Committee member) / Barnes, M. Elizabeth (Committee member) / School of Human Evolution & Social Change (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Dielectrophoresis has been shown in the recent past to successfully separate bioparticles of very subtle differences at high resolutions using biophysical forces. In this study, we test the biophysical differences of methicillin resistant and susceptible Staph. aureus that are known to have very similar genomes by using a modified gradient insulator-based dielectrophoresis device (g-iDEP). MRSA is commonly seen in hospitals and is the leading killer of infectious bacteria, claiming the lives of around 10,000 people annually. G-iDEP improves many capabilities within the DEP field including sample size, cost, ease of use and analysis time. This is a promising foundation to creating a more clinically optimized diagnostic tool for both separation and detection of bacteria in the healthcare field. The capture on-set potential for fluorescently tagged MRSA (801 ± 34V) is higher than fluorescently tagged MSSA (610 ± 32V), resulting in a higher electrokinetic to dielectrophoretic mobility ratio for MRSA. Since the strains have proven to be genomically similar through sequencing, it is reasonable to attribute this significant biophysical difference to the added PBP2a enzyme in MRSA. These results are consistent with other bacterial studied within in this device and have proven to be reproducible.
ContributorsSmithers, Jared (Author) / Hayes, Mark (Thesis director) / Woodbury, Neal (Committee member) / School of Criminology and Criminal Justice (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
The rise in community-associated methicillin-resistant Staphylococcus aureus (MRSA) infections and the ability of the organism to develop resistance to antibiotics necessitate new treatment methods for MRSA. Geopolymers (GPs) are cheap, porous materials that have demonstrated adsorptive capabilities. In this study, GPs were investigated for their ability to adsorb whole MRSA cells and MRSA secreted proteins [culture filtrate proteins (CFPs)] as a complementary method of controlling MRSA infections. GPs have been synthesized with variable pore sizes (meso/macro scale) and further modified with stearic acid (SA) to increase surface hydrophobicity. Four GPs (SA-macroGP, macroGP, SA-mesoGP, and mesoGP) were incubated with whole cells and with CFPs to quantify GP adsorption capabilities. Following MRSA culture incubation with GPs, unbound MRSA cells were filtered and plated to determine cell counts. Following CFP incubation with GPs, unbound CFPs were separated via SDS-PAGE, stained with SYPRO Ruby, and analyzed using densitometry. Results indicate that macroGP was the most effective at adsorbing whole MRSA cells. Visual banding patterns and densitometry quantitation indicate that SA-mesoGP was the most effective at adsorbing CFP. Ultimately, GP-based products may be further developed as nonselective or selective adsorbents and integrated into fibrous materials for topical applications.
ContributorsGanser, Collin (Co-author, Co-author) / Haydel, Shelley E. (Thesis director) / Seo, Don (Committee member) / Borges, Chad (Committee member) / School of Earth and Space Exploration (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Diabesity is a global epidemic affecting millions worldwide. Diabesity is the term given to the link between obesity and Type II diabetes. It is estimated that ~90% of patients diagnosed with Type II diabetes are overweight or have struggled with excess body fat in the past. Type II diabetes is characterized by insulin resistance which is an impaired response of the body to insulin that leads to high blood glucose levels. Adipose tissue, previously thought of as an inert tissue, is now recognized as a major endocrine organ with an important role in the body's immune response and the development of chronic inflammation. It is speculated that adipose tissue inflammation is a major contributor to insulin resistance particular to Type II diabetes. This literature review explores the popular therapeutic targets and marketed drugs for the treatment of Type II diabetes and their role in decreasing adipose tissue inflammation. rAGE is currently in pre-clinical studies as a possible target to combat adipose tissue inflammation due to its relation to insulin resistance. Metformin and Pioglitazone are two drugs already being marketed that use unique chemical pathways to increase the production of insulin and/or decrease blood glucose levels. Sulfonylureas is one of the first FDA approved drugs used in the treatment of Type II diabetes, however, it has been discredited due to its life-threatening side effects. Bariatric surgery is a form of invasive surgery to rid the body of excess fat and has shown to normalize blood glucose levels. These treatments are all secondary to lifestyle changes, such as diet and exercise which can help halt the progression of Type II diabetes patients.
ContributorsRobles, Alondra Maria (Author) / Woodbury, Neal (Thesis director) / Redding, Kevin (Committee member) / Allen, James (Committee member) / Hendrickson, Kirstin (Committee member) / Sanford School of Social and Family Dynamics (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
The purpose of this thesis creative project was to create an educational video to present research findings on the increasingly important issue of human biospecimen preanalytic variables. When a human biospecimen, such as blood, urine, or tissue, is removed from the body, it is subjected to a plethora of variables that are not recorded or regulated in a vast majority of cases. Frequently, these samples arrive at the research or pathology lab with an unknown history, then undergo analysis for translational research purposes, or to guide clinical management decisions. Thus, compromised specimen quality caused by preanalytic variables has substantial, and potentially devastating, downstream effects. To identify the preanalytic variables with the greatest impact on blood and tissue specimen quality, 45 articles were gathered using PubMed and Google Scholar databases and cited. Based on the articles, the top five variables with the most detrimental effects were identified for both blood and tissue samples. Multiple sets of parameters ensuring specimen fitness were compared for each of the five variables for each specimen type. Then, specific parameters guaranteeing the fitness of the greatest number of analytes were verified. To present the research findings in greater detail, a paper was written that focused on identifying the top variables and key parameters to ensure analyte fitness. To present the overall issue in an easy-to-digest format, a storyboard and script were created as a guideline for a final video project. Ultimately, two alternate versions of the video were created to pertain to the audience of choice (one version for patients, one version for professionals). It is the hope that these videos will be used as educational tools to continue efforts to standardize and enforce human biospecimen preanalytic variable parameters. This is a necessary step to improve the accuracy of our biomedical research data and the healthcare of patients worldwide.
ContributorsAzcarate, Heather (Author) / Compton, Carolyn (Thesis director) / LaBaer, Joshua (Committee member) / Borges, Chad (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor)
Created2018-12