Showing 111 - 120 of 722 Items
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.
Data Set for North American Colleges and Universities with Italian and Digital Humanities Programs
Date: 2016-09-13
Creator: Crystal Hall
Access: Open access
- This data set represents a first attempt to identify the North American colleges and universities that offer Italian courses at any level and also have support for digital humanities (DH) pedagogy or scholarship at any level. The list of schools with Italian programs was developed using the American Association of Teachers of Italian (AATI) list of undergraduate and graduate programs and College Source as of July 2016. The list was supplemented by checking if institutions listed with CenterNet (for Digital Humanities Centers) also have Italian programs. Overall, 10% of the Italian programs identified were not included in the AATI list, from the level of service courses through Masters degree. A search of each institution’s website was then performed to determine the level of DH resources available. Based on this collected data, 70% of North American colleges and universities that offer Italian also offer support for digital humanities courses or research through a center/lab, courses, major or minor programs, certificates, or graduate programs. A supplemental code sheet is available. Further analysis is provided in the author’s working paper “Digital Humanities & Italian Studies: Intersections and Oppositions” that is part of the State of the Discipline symposium organized by Wellesley College, October 1, 2016. (The data has been updated since the circulation of that paper, so numbers may not match.) The topic will be addressed in more detail based on the related survey and presentation at MLA 2017.
Magni, isabella, lia markey, and maddalena signorini, eds. Italian paleography. other.
Date: 2020-01-01
Creator: Crystal Hall
Access: Open access
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.
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 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.
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.
Analysis of the yeast arginine methyltransferase Hmt1p/Rmt1p and its in vivo function. Cofactor binding and substrate interactions
Date: 2000-02-04
Creator: Anne E. McBride
Valerie H. Weiss
Heidi K. Kim
James M. Hogle
Pamela A., Silver
Access: Open access
- Many eukaryotic RNA-binding proteins are modified by methylation of arginine residues. The yeast Saccharomyces cerevisiae contains one major arginine methyltransferase, Hmt1p/Rmt1p, which is not essential for normal cell growth. However, cells missing HMT1 and also bearing mutations in the mRNA-binding proteins Np13p or Cbp80p can no longer survive, providing genetic backgrounds in which to study Hmt1p function. We now demonstrate that the catalytically active form of Hmt1p is required for its activity in vivo. Amino acid changes in the putative Hmt1p S-adenosyl-L-methionine-binding site were generated and shown to be unable to catalyze methylation of Np13p in vitro and in vivo or to restore growth to strains that require HMT1. In addition these mutations affect nucleocytoplasmic transport of Np13p. A cold- sensitive mutant of Hmt1p was generated and showed reduced methylation of Np13p, but not of other substrates, at 14 °C. These results define new aspects of Hmt1 and reveal the importance of its activity in vivo.
Optical proxy for phytoplankton biomass in the absence of photophysiology: Rethinking the absorption line height
Date: 2013-01-01
Creator: Collin S. Roesler
Andrew H. Barnard
Access: Open access
- The pigment absorption peak in the red waveband observed in phytoplankton and particulate absorption spectra is primarily associated with chlorophyll-a and exhibits much lower pigment packaging compared to the blue peak. The minor contributions to the signature by accessory pigments can be largely removed by computing the line height absorption at 676 nm above a linear background between approximately 650 nm and 715 nm. The line height determination is also effective in removing the contributions to total or particulate absorption by colored dissolved organic matter and non-algal particles, and is relatively independent of the effects of biofouling. The line height absorption is shown to be significantly related to the extracted chlorophyll concentration over a large range of natural optical regimes and diverse phytoplankton cultures. Unlike the in situ fluorometric method for estimating chlorophyll, the absorption line height is not sensitive to incident irradiance, in particular non-photochemical quenching. The combination of the two methods provides a combination of robust phytoplankton biomass estimates, pigment based taxonomic information and a means to estimate the photosynthetic parameter, , the irradiance at which photosynthesis transitions from light limitation to light saturation. © 2013 The Authors. E K