Matching Items (653)
Description
It is well known that deficiencies in key chemical elements (such as phosphorus, P) can reduce animal growth; however, recent empirical data have shown that high levels of dietary nutrients can also reduce animal growth. In ecological stoichiometry, this phenomenon is known as the "stoichiometric knife edge," but its underlying

It is well known that deficiencies in key chemical elements (such as phosphorus, P) can reduce animal growth; however, recent empirical data have shown that high levels of dietary nutrients can also reduce animal growth. In ecological stoichiometry, this phenomenon is known as the "stoichiometric knife edge," but its underlying mechanisms are not well-known. Previous work has suggested that the crustacean zooplankter Daphnia reduces its feeding rates on phosphorus-rich food, causing low growth due to insufficient C (energy) intake. To test for this mechanism, feeding rates of Daphnia magna on algae (Scenedesmus acutus) differing in C:P ratio (P content) were determined. Overall, there was a significant difference among all treatments for feeding rate (p < 0.05) with generally higher feeding rates on P-rich algae. These data indicate that both high and low food C:P ratio do affect Daphnia feeding rate but are in contradiction with previous work that showed that P-rich food led to strong reductions in feeding rate. Additional experiments are needed to gain further insights.
ContributorsSchimpp, Sarah Ann (Author) / Elser, James (Thesis director) / Neuer, Susanne (Committee member) / Peace, Angela (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / School of Sustainability (Contributor)
Created2014-05
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Description
Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the

Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergent evolution.
ContributorsLi, Dianfan (Author) / Stansfeld, Phillip J. (Author) / Sansom, Mark S. P. (Author) / Keogh, Aaron (Author) / Vogeley, Lutz (Author) / Howe, Nicole (Author) / Lyons, Joseph A. (Author) / Aragao, David (Author) / Fromme, Petra (Author) / Fromme, Raimund (Author) / Basu, Shibom (Author) / Grotjohann, Ingo (Author) / Kupitz, Christopher (Author) / Rendek, Kimberley (Author) / Weierstall, Uwe (Author) / Zatsepin, Nadia (Author) / Cherezov, Vadim (Author) / Liu, Wei (Author) / Bandaru, Sateesh (Author) / English, Niall J. (Author) / Gati, Cornelius (Author) / Barty, Anton (Author) / Yefanov, Oleksandr (Author) / Chapman, Henry N. (Author) / Diederichs, Kay (Author) / Messerschmidt, Marc (Author) / Boutet, Sebastien (Author) / Williams, Garth J. (Author) / Seibert, M. Marvin (Author) / Caffrey, Martin (Author) / College of Liberal Arts and Sciences (Contributor) / School of Molecular Sciences (Contributor) / Biodesign Institute (Contributor) / Applied Structural Discovery (Contributor) / Department of Physics (Contributor)
Created2015-12-17
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Description
Large quantities of sodic and alkaline bauxite residue are produced globally as a by-product from alumina refineries. Ecological stoichiometry of key elements [nitrogen (N) and phosphorus (P)] plays a critical role in establishing vegetation cover in bauxite residue sand (BRS). Here we examined how changes in soil chemical properties over

Large quantities of sodic and alkaline bauxite residue are produced globally as a by-product from alumina refineries. Ecological stoichiometry of key elements [nitrogen (N) and phosphorus (P)] plays a critical role in establishing vegetation cover in bauxite residue sand (BRS). Here we examined how changes in soil chemical properties over time in rehabilitated sodic and alkaline BRS affected leaf N to P stoichiometry of native species used for rehabilitation. Both Ca and soil pH influenced the shifts in leaf N:P ratios of the study species as supported by consistently significant positive relationships (P < 0.001) between these soil indices and leaf N:P ratios. Shifts from N to P limitation were evident for N-fixing species, while N limitation was consistently experienced by non-N-fixing plant species. In older rehabilitated BRS embankments, soil and plant indices (Ca, Na, pH, EC, ESP and leaf N:P ratios) tended to align with those of the natural ecosystem, suggesting improved rehabilitation performance. These findings highlight that leaf N:P stoichiometry can effectively provide a meaningful assessment on understanding nutrient limitation and productivity of native species used for vegetating highly sodic and alkaline BRS, and is a crucial indicator for assessing ecological rehabilitation performance.
ContributorsGoloran, Johnvie B. (Author) / Chen, Chengrong (Author) / Phillips, Ian R. (Author) / Elser, James (Author) / College of Liberal Arts and Sciences (Contributor) / School of Life Sciences (Contributor)
Created2015-10-07
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Description
Phytochromes are a family of photoreceptors that control light responses of plants, fungi and bacteria. A sequence of structural changes, which is not yet fully understood, leads to activation of an output domain. Time-resolved serial femtosecond crystallography (SFX) can potentially shine light on these conformational changes. Here we report the

Phytochromes are a family of photoreceptors that control light responses of plants, fungi and bacteria. A sequence of structural changes, which is not yet fully understood, leads to activation of an output domain. Time-resolved serial femtosecond crystallography (SFX) can potentially shine light on these conformational changes. Here we report the room temperature crystal structure of the chromophore-binding domains of the Deinococcus radiodurans phytochrome at 2.1 Å resolution. The structure was obtained by serial femtosecond X-ray crystallography from microcrystals at an X-ray free electron laser. We find overall good agreement compared to a crystal structure at 1.35 Å resolution derived from conventional crystallography at cryogenic temperatures, which we also report here. The thioether linkage between chromophore and protein is subject to positional ambiguity at the synchrotron, but is fully resolved with SFX. The study paves the way for time-resolved structural investigations of the phytochrome photocycle with time-resolved SFX.
ContributorsEdlund, Petra (Author) / Takala, Heikki (Author) / Claesson, Elin (Author) / Henry, Leocadie (Author) / Dods, Robert (Author) / Lehtivuori, Heli (Author) / Panman, Matthijs (Author) / Pande, Kanupriya (Author) / White, Thomas (Author) / Nakane, Takanori (Author) / Berntsson, Oskar (Author) / Gustavsson, Emil (Author) / Bath, Petra (Author) / Modi, Vaibhav (Author) / Roy Chowdhury, Shatabdi (Author) / Zook, James (Author) / Berntsen, Peter (Author) / Pandey, Suraj (Author) / Poudyal, Ishwor (Author) / Tenboer, Jason (Author) / Kupitz, Christopher (Author) / Barty, Anton (Author) / Fromme, Petra (Author) / Koralek, Jake D. (Author) / Tanaka, Tomoyuki (Author) / Spence, John (Author) / Liang, Mengning (Author) / Hunter, Mark S. (Author) / Boutet, Sebastien (Author) / Nango, Eriko (Author) / Moffat, Keith (Author) / Groenhof, Gerrit (Author) / Ihalainen, Janne (Author) / Stojkovic, Emina A. (Author) / Schmidt, Marius (Author) / Westenhoff, Sebastian (Author) / College of Liberal Arts and Sciences (Contributor) / School of Molecular Sciences (Contributor) / Biodesign Institute (Contributor) / Applied Structural Discovery (Contributor) / Department of Physics (Contributor)
Created2016-10-19
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Description
Serial femtosecond crystallography (SFX) using X-ray free-electron laser sources is an emerging method with considerable potential for time-resolved pump-probe experiments. Here we present a lipidic cubic phase SFX structure of the light-driven proton pump bacteriorhodopsin (bR) to 2.3 Å resolution and a method to investigate protein dynamics with modest sample requirement.

Serial femtosecond crystallography (SFX) using X-ray free-electron laser sources is an emerging method with considerable potential for time-resolved pump-probe experiments. Here we present a lipidic cubic phase SFX structure of the light-driven proton pump bacteriorhodopsin (bR) to 2.3 Å resolution and a method to investigate protein dynamics with modest sample requirement. Time-resolved SFX (TR-SFX) with a pump-probe delay of 1 ms yields difference Fourier maps compatible with the dark to M state transition of bR. Importantly, the method is very sample efficient and reduces sample consumption to about 1 mg per collected time point. Accumulation of M intermediate within the crystal lattice is confirmed by time-resolved visible absorption spectroscopy. This study provides an important step towards characterizing the complete photocycle dynamics of retinal proteins and demonstrates the feasibility of a sample efficient viscous medium jet for TR-SFX.
ContributorsNogly, Przemyslaw (Author) / Panneels, Valerie (Author) / Nelson, Garrett (Author) / Gati, Cornelius (Author) / Kimura, Tetsunari (Author) / Milne, Christopher (Author) / Milathianaki, Despina (Author) / Kubo, Minoru (Author) / Wu, Wenting (Author) / Conrad, Chelsie (Author) / Coe, Jesse (Author) / Bean, Richard (Author) / Zhao, Yun (Author) / Bath, Petra (Author) / Dods, Robert (Author) / Harimoorthy, Rajiv (Author) / Beyerlein, Kenneth R. (Author) / Rheinberger, Jan (Author) / James, Daniel (Author) / Deponte, Daniel (Author) / Li, Chufeng (Author) / Sala, Leonardo (Author) / Williams, Garth J. (Author) / Hunter, Mark S. (Author) / Koglin, Jason E. (Author) / Berntsen, Peter (Author) / Nango, Eriko (Author) / Iwata, So (Author) / Chapman, Henry N. (Author) / Fromme, Petra (Author) / Frank, Matthias (Author) / Abela, Rafael (Author) / Boutet, Sebastien (Author) / Barty, Anton (Author) / White, Thomas A. (Author) / Weierstall, Uwe (Author) / Spence, John (Author) / Neutze, Richard (Author) / Schertler, Gebhard (Author) / Standfuss, Jorg (Author) / College of Liberal Arts and Sciences (Contributor) / Department of Physics (Contributor) / Department of Chemistry and Biochemistry (Contributor) / Biodesign Institute (Contributor) / Applied Structural Discovery (Contributor) / School of Molecular Sciences (Contributor)
Created2016-08-22
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Description

Serial femtosecond crystallography requires reliable and efficient delivery of fresh crystals across the beam of an X-ray free-electron laser over the course of an experiment. We introduce a double-flow focusing nozzle to meet this challenge, with significantly reduced sample consumption, while improving jet stability over previous generations of nozzles. We

Serial femtosecond crystallography requires reliable and efficient delivery of fresh crystals across the beam of an X-ray free-electron laser over the course of an experiment. We introduce a double-flow focusing nozzle to meet this challenge, with significantly reduced sample consumption, while improving jet stability over previous generations of nozzles. We demonstrate its use to determine the first room-temperature structure of RNA polymerase II at high resolution, revealing new structural details. Moreover, the double flow-focusing nozzles were successfully tested with three other protein samples and the first room temperature structure of an extradiol ring-cleaving dioxygenase was solved by utilizing the improved operation and characteristics of these devices.

ContributorsOberthuer, Dominik (Author) / Knoska, Juraj (Author) / Wiedorn, Max O. (Author) / Beyerlein, Kenneth R. (Author) / Bushnell, David A. (Author) / Kovaleva, Elena G. (Author) / Heymann, Michael (Author) / Gumprecht, Lars (Author) / Kirian, Richard (Author) / Barty, Anton (Author) / Mariani, Valerio (Author) / Tolstikova, Aleksandra (Author) / Adriano, Luigi (Author) / Awel, Salah (Author) / Barthelmess, Miriam (Author) / Dorner, Katerina (Author) / Xavier, P. Lourdu (Author) / Yefanov, Oleksandr (Author) / James, Daniel (Author) / Nelson, Garrett (Author) / Wang, Dingjie (Author) / Calvey, George (Author) / Chen, Yujie (Author) / Schmidt, Andrea (Author) / Szczepek, Michael (Author) / Frielingsdorf, Stefan (Author) / Lenz, Oliver (Author) / Snell, Edward (Author) / Robinson, Philip J. (Author) / Sarler, Bozidar (Author) / Belsak, Grega (Author) / Macek, Marjan (Author) / Wilde, Fabian (Author) / Aquila, Andrew (Author) / Boutet, Sebastien (Author) / Liang, Mengning (Author) / Hunter, Mark S. (Author) / Scheerer, Patrick (Author) / Lipscomb, John D. (Author) / Weierstall, Uwe (Author) / Kornberg, Roger D. (Author) / Spence, John (Author) / Pollack, Lois (Author) / Chapman, Henry N. (Author) / Bajt, Sasa (Author) / College of Liberal Arts and Sciences (Contributor) / Department of Physics (Contributor)
Created2017-03-16
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Description

For decades, understanding the complexity of behaviors, motivations, and values has interested researchers across various disciplines. So much so that there are numerous terms, frameworks, theories, and studies devoted to understanding these complexities and how they interact and evolve into actions. However, little research has examined how employee behaviors translate

For decades, understanding the complexity of behaviors, motivations, and values has interested researchers across various disciplines. So much so that there are numerous terms, frameworks, theories, and studies devoted to understanding these complexities and how they interact and evolve into actions. However, little research has examined how employee behaviors translate into the work environment, particularly regarding perceived organizational success. This study advances research by quantitatively assessing how a greater number of individual employees’ pro-environmental behaviors are related to the perceived success of environmentally sustainable workplace activities. We have concluded that the more pro-environmental behaviors an employee embodies, the more positively they perceive the success of their local government's sustainable purchasing policy. Additionally, other factors matter, including organizational behaviors, like training, innovation, and reduction of red tape.

ContributorsFox, Angela (Author) / Darnall, Nicole (Thesis advisor) / Bretschneider, Stuart (Committee member) / Behravesh, Shirley-Ann (Committee member) / School of Sustainability (Contributor)
Created2022-04-19
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Description

BACKGROUND: The City of Phoenix initiated the HeatReady program in 2018 to prepare for extreme heat, as there was no official tool, framework, or mechanism at the city level to manage extreme heat. The current landscape of heat safety culture in schools, which are critical community hubs, has received less

BACKGROUND: The City of Phoenix initiated the HeatReady program in 2018 to prepare for extreme heat, as there was no official tool, framework, or mechanism at the city level to manage extreme heat. The current landscape of heat safety culture in schools, which are critical community hubs, has received less illumination. HeatReady Schools—a critical component of a HeatReady City—are those that are increasingly able to identify, prepare for, mitigate, track, and respond to the negative impacts of schoolgrounds heat. However, minimal attention has been given to formalize heat preparedness in schools to mitigate high temperatures and health concerns in schoolchildren, a heat-vulnerable population. This study set out to understand heat perceptions, (re)actions, and recommendations of key stakeholders and to identify critical themes around heat readiness. METHODS: An exploratory sequential mixed-methods case study approach was used. These methods focused on acquiring new insight on heat perceptions at elementary schools through semi-structured interviews using thematic analysis and the Delphi panel. Participants included public health professionals and school community members at two elementary schools—one public charter, one public—in South Phoenix, Arizona, a region that has been burdened historically with inequitable distribution of heat resources due to environmental racism and injustices. RESULTS: Findings demonstrated that 1) current heat safety resources are available but not fully utilized within the school sites, 2) expert opinions support that extreme heat readiness plans must account for site-specific needs, particularly education as a first step, and 3) students are negatively impacted by the effects of extreme heat, whether direct or indirect, both inside and outside the classroom. CONCLUSIONS: From key informant interviews and a Delphi panel, a list of 30 final recommendations were developed as important actions to be taken to become “HeatReady.” Future work will apply these recommendations in a HeatReady School Growth Tool that schools can tailor be to their individual needs to improve heat safety and protection measures at schools.

ContributorsShortridge, Adora (Author) / Walker, William VI (Author) / White, Dave (Committee member) / Guardaro, Melissa (Committee member) / Hondula, David M. (Committee member) / Vanos, Jennifer K. (Committee member) / School of Sustainability (Contributor)
Created2022-04-18
Description
Pima was not the original name for the tribe of the Native Americans that lived along the Gila River, but their name is only one of many changes this tribe has faced due to the influence of outside sources. Pima was a name given to this tribe by the Spaniards

Pima was not the original name for the tribe of the Native Americans that lived along the Gila River, but their name is only one of many changes this tribe has faced due to the influence of outside sources. Pima was a name given to this tribe by the Spaniards during the 1600s. Throughout history the Pima have fought not only for their rights as a nation, but also for the rights of their beloved river, the Gila River. The relationship between the Pima tribe and Gila River is a very strong and deep connection. In fact, the Pima call themselves A-a'tam, which means "the people," and they identify with the Papago, a historical name for the Indians in the Sonoran Desert. A'kimult, which means "river" was added to their name as well. Being known as the River People may fit perfectly with this tribe due to their close knit and respectful relationship with the river over the decades (Russell, "The Pima Indians, 1975). Today the Pima call the Gila River Indian Community their main Tribal headquarters, which is located south of Phoenix. The Gila River Indian Community (GRIC) is part of both the Pinal and Maricopa counties and has a land area of 583.749 square miles ("Brownfields", 2010). Water deprivation and a bleak agricultural economy are challenges facing the Pima, which historically were strong in both areas. The Gila River has gone from a naturally flowing river to a restricted and nearly dried up waterbed. This research paper will examine the changes that both the Pima and the Gila River have undergone since settlers began to claim land in the late 1800's. It is my goal to look into the natural history and ecology of the Gila River and explain how this change has affected the Pima and their sustainability as a tribe. The ultimate goal is to have information easily accessible for reference for future research projects and to ] provide background information to help implement new programs and projects that will benefit the GRIC. Understanding the relationship between the Gila Valley and Pima will present areas where sustainable projects can improve the economy and society as a whole. The Native Americans who will be specifically addressed during this research are the tribes on the GRIC, which comprise the Akimel O-odham (Pima) and Pee Posh (Maricopa). These communities have a resident population of 15,084 and are located in the Maricopa and Pinal counties of central Arizona, to the south and east of metropolitan Phoenix ("Brownfields", 2010). Today the community is 372,000 acres and varies with an elevation of 935 feet to 1,450 feet ("Gila River", 2012). Literature will be the primary area of research along with informal discussions with employees of the GRIC. The Pimas' beliefs, interests, and practices will be addressed and researched; and review of the literature that deals with each problem they have faced as a result of the changing economy and society. By researching the relationship and proposing new ideas to help maintain the GRIC it will assure that the interests of the Pima are the priority. The potential that this research project can offer must encompass cultural sustainability, which is "developing, renewing and maintaining human cultures that create positive, enduring relationships with other peoples and the natural world" (Hawkes, 2001).
ContributorsRagan, McKenzie (Author) / Martinez, David (Thesis director) / Larson, Kelli (Committee member) / Manetta, Carol (Committee member) / Barrett, The Honors College (Contributor) / School of Sustainability (Contributor) / College of Public Programs (Contributor)
Created2012-12
Description
This project aims to provide a contextualized history of the Sky Harbor Neighborhood Association‟s community collective action efforts. The Sky Harbor Neighborhood (SHN) of East Phoenix is bounded on the West by 24th St., on the East by 32nd St., on the North by Roosevelt St., and the South by

This project aims to provide a contextualized history of the Sky Harbor Neighborhood Association‟s community collective action efforts. The Sky Harbor Neighborhood (SHN) of East Phoenix is bounded on the West by 24th St., on the East by 32nd St., on the North by Roosevelt St., and the South by Washington Street. SHN is a majority Latino, low-income, working class community (U.S. Census Bureau, 2010) that faces a variety of challenges including low walkability due to inadequate pedestrian infrastructure, low tree coverage, and crime. East Van Buren St., which has a reputation for being one of Phoenix‟s red-light districts, splits the neighborhood in two. In addition, the SHN lacks some key amenities such as grocery stores and is partly considered a food desert by the United States Department of Agriculture (USDA Economic Research Service, 2012).
ContributorsPearson, Kimberly (Author) / Golub, Aaron (Thesis director) / Wiek, Arnim (Committee member) / York, Abigail (Committee member) / Barrett, The Honors College (Contributor) / College of Liberal Arts and Sciences (Contributor) / School of Sustainability (Contributor)
Created2012-12