Faculty Scholarship
Showing 101 - 110 of 733 Items
Dismantling the bacterial glycocalyx: Chemical tools to probe, perturb, and image bacterial glycans
Date: 2021-07-15
Creator: Phuong Luong, Danielle H. Dube
Access: Open access
- The bacterial glycocalyx is a quintessential drug target comprised of structurally distinct glycans. Bacterial glycans bear unusual monosaccharide building blocks whose proper construction is critical for bacterial fitness, survival, and colonization in the human host. Despite their appeal as therapeutic targets, bacterial glycans are difficult to study due to the presence of rare bacterial monosaccharides that are linked and modified in atypical manners. Their structural complexity ultimately hampers their analytical characterization. This review highlights recent advances in bacterial chemical glycobiology and focuses on the development of chemical tools to probe, perturb, and image bacterial glycans and their biosynthesis. Current technologies have enabled the study of bacterial glycosylation machinery even in the absence of detailed structural information.
Post-translational modification directs nuclear and hyphal tip localization of Candida albicans mRNA-binding protein Slr1
Date: 2017-05-01
Creator: Chaiyaboot Ariyachet, Christian Beißel, Xiang Li, Selena Lorrey, Olivia, Mackenzie, Patrick M. Martin, Katharine O'Brien, Tossapol Pholcharee, Sue Sim, Heike Krebber, Anne E. McBride
Access: Open access
- The morphological transition of the opportunistic fungal pathogen Candida albicans from budding to hyphal growth has been implicated in its ability to cause disease in animal models. Absence of SR-like RNA-binding protein Slr1 slows hyphal formation and decreases virulence in a systemic candidiasis model, suggesting a role for post-transcriptional regulation in these processes. SR (serine–arginine)-rich proteins influence multiple steps in mRNA metabolism and their localization and function are frequently controlled by modification. We now demonstrate that Slr1 binds to polyadenylated RNA and that its intracellular localization is modulated by phosphorylation and methylation. Wildtype Slr1-GFP is predominantly nuclear, but also co-fractionates with translating ribosomes. The non-phosphorylatable slr1-6SA-GFP protein, in which six serines in SR/RS clusters are substituted with alanines, primarily localizes to the cytoplasm in budding cells. Intriguingly, hyphal cells display a slr1-6SA-GFP focus at the tip near the Spitzenkörper, a vesicular structure involved in molecular trafficking to the tip. The presence of slr1-6SA-GFP hyphal tip foci is reduced in the absence of the mRNA-transport protein She3, suggesting that unphosphorylated Slr1 associates with mRNA–protein complexes transported to the tip. The impact of SLR1 deletion on hyphal formation and function thus may be partially due to a role in hyphal mRNA transport.
The Impact of Ride-Hailing Services on Public Transportation Use: A Discontinuity Regression Analysis
Date: 2017-05-26
Creator: Nicole Sadowsky, Erik Nelson
Access: Open access
- Since 2011, the private ride-hailing companies Uber and Lyft have expanded into more and more US cities. We use regression discontinuity design to examine the impact of Uber and Lyft’s entry on public transportation use in the US’ largest urban areas. In most cases, entry into cities by the two ride-hailing companies was staggered: Uber entered first followed some months later by Lyft. We find that public transportation use increased in an urban area, all else equal, immediately following the first entry. However, we find that the spike in public transportation use after first entry disappeared following the entry of the second company. In fact there is some evidence that monthly public transportation ridership levels fell below their pre-first entry levels. In other words, the joint presence of the two major private ride-hailing services transformed ride-hailing services from a public transportation complement to a public transportation substitute, at least in the studied urban areas. We speculate that the first entrant complemented public transportation use for some in an urban area by solving the “last-mile” problem and by providing a potentially safer option at night when public transportation service has been reduced. However, we speculate the second entrant is likely to have spurred price competition in the urban area’s ride-hailing duopoly market and an increase in ride-hailing car supply. This competitive effect could have tipped the scales, making an entire trip with a ride-hailing service more cost-effective and convenient than splitting a trip between a ride-share company and public transportation.
A new global ethic»: A history of the United Nations International Environmental Education Program, 1975-1995
Date: 2020-12-01
Creator: Charles Dorn
Access: Open access
- In 1975, the United Nations, under the auspices of its Educational, Scientific and Cultural Organization (UNESCO) and Environment Program (UNEP), established the International Environmental Education Program (IEEP). For two decades, IEEP aimed to accomplish goals ascribed to it by UNESCO member states and fostered communication across the international community through Connect, the UNESCO-UNEP environmental education newsletter. After reviewing UNESCO’s early involvement with the environment, this study examines IEEP’s development, beginning with its conceptual grounding in the 1968 UNESCO Biosphere Conference. It examines the 1972 United Nations Conference on the Human Environment held in Stockholm, moves on to the UNESCO-UNEP 1975 Belgrade Workshop, and continues with the world’s first intergovernmental conference dedicated to environmental education held in Tbilisi in 1977. The paper then uses Connect to trace changes in the form and content of environmental education. Across two decades, environmental education shifted from providing instruction about nature protection and natural resource conservation to fostering an environmental ethic through a problems-based, interdisciplinary study of the ecology of the total environment to adopting the concept of sustainable development. IEEP ultimately met with mixed success. Yet it was the primary United Nations program assigned the task of creating and implementing environmental education globally and thus offers a particularly useful lens through which to analyze changes in the international community’s understanding of the concept of the environment over time.
State of the Arg: Protein methylation at arginine comes of age
Date: 2001-07-13
Creator: Anne E. McBride, Pamela A. Silver
Access: Open access
The distributional impact of a green payment policy for organic fruit
Date: 2019-02-01
Creator: Erik Nelson, John Fitzgerald, Nathan Tefft
Access: Open access
- Consumer spending on organic food products has grown rapidly. Some claim that organics have ecological, equity, and health advantages over conventional food and therefore should be subsidized. Here we explore the distributive impacts of an organic fruit subsidy that reduces the retail price of organic fruit in the US by 10 percent. We estimate the impact of the subsidy on organic fruit demand in a representative poor, middle income, and rich US household using three analytical methods; including two econometric and one machine learning. We do not find strong evidence of regressive redistribution due to our simulated organic fruit subsidy; the poor household’s relative reaction to the subsidy is not much different than the reaction at the other two households. However, the infra-marginal savings from the subsidy tend to be larger in richer households.
Implementing the Optimal Provision of Ecosystem Services
Date: 2013-08-01
Creator: Stephen Polasky, David Lewis, Andrew Plantinga, Erik Nelson
Access: Open access
- Many ecosystem services are public goods whose provision depends on the spatial pattern of land use. The pattern of land use is often determined by the decisions of multiple private landowners. Increasing the provision of ecosystem services, while beneficial for society as a whole, may be costly to private landowners. A regulator interested in providing incentives to landowners for increased provision of ecosystem services often lacks complete information on landowners’ costs. The combination of spatially-dependent benefits and asymmetric cost information means that the optimal provision of ecosystem services cannot be achieved using standard regulatory or payment for ecosystem services (PES) approaches. Here we show that an auction that pays a landowner for the increased value of ecosystem services generated by the landowner’s actions provides incentives for landowners to truthfully reveal cost information, and allows the regulator to implement the optimal provision of ecosystem services, even in the case with spatially-dependent benefits and asymmetric information.
Measuring the Relative Importance of Different Agricultural Inputs to Global and Regional Crop Yield Growth Since 1975
Date: 2016-09-01
Creator: Erik Nelson, Clare Bates Congdon
Access: Open access
- We identify the agricultural inputs that drove the growth in global and regional crop yields from 1975 to the mid-2000s. We find that improvements in agricultural technology, increased fertilizer use, and changes in crop mix around the world explained most of the gain in global crop yields, although impacts varied across the latitude gradient. Climate change over this time period caused yields to be only slightly lower than they would have been otherwise. In some cases cropland extensification had as much of a negative impact on global and regional yields as climate change. To maintain the momentum in yield growth across the globe 1) use of agricultural chemicals and investment in agricultural technology in the tropics must increase rapidly and 2) international trade in agricultural products must expand significantly.
Magni, isabella, lia markey, and maddalena signorini, eds. Italian paleography. other.
Date: 2020-01-01
Creator: Crystal Hall
Access: Open access