Faculty Scholarship
Showing 551 - 560 of 733 Items
Erratum: The 'obligate diploid' Candida albicans forms mating-competent haploids (Nature (2013) 494 (55-59) DOI: 10.1038/nature11865)
Date: 2016-02-11
Creator: Meleah A. Hickman, Guisheng Zeng, Anja Forche, Matthew P. Hirakawa, Darren, Abbey, Benjamin D. Harrison, Yan Ming Wang, Ching Hua Su, Richard J. Bennett, Yue Wang, Judith Berman
Access: Open access
An Arabidopsis serine/threonine kinase homologue with an epidermal growth factor repeat selected in yeast for its specificity for a thylakoid membrane protein
Date: 1992-01-01
Creator: Bruce D. Kohorn, Steven Lane, Tracy A. Smith
Access: Open access
- A number of molecules have recently been described that effect the correct transport and assembly of cytoplasmically synthesized proteins to cellular membranes. To identify proteins that bind or modify other proteins during the process of membrane translocation, we developed a yeast selection scheme that employs the yeast transcriptional activator GAL4. This selection facilitates the isolation of cDNAs that encode proteases and binding proteins for known target peptide sequences. We report the isolation of an Arabidopsis cDNA encoding a polypeptide that can interact with the amino terminus of a light-harvesting chlorophyll a/b-binding protein (LHCP), a cytoplasmically synthesized protein that is integral to the chloroplast thylakoid membrane. The cDNA was selected in yeast from an Arabidopsis expression library for its ability to inhibit a transcriptional activator GAL4-LHCP fusion protein, but not inhibit native GAL4 protein. The LHCP aminoterminal sequences included in the fusion protein are known to regulate LHCP biogenesis and function. The Arabidopsis cDNA encodes a 595-amino acid protein with at least two functional domains, one with similarity to the family of proteinserine/threonine kinases and another that contains an epidermal growth factor repeat. The identification of an EGF repeat in Arabidopsis indicates that the motif is conserved between the plant and animal kingdoms. Hybridization studies indicate that this gene is likely to be present in other genera of plants. Its mRNA is detected in green leaves but not in other plant tissues or in etiolated plants. The specificity in yeast and the expression pattern in plants together are suggestive of a role for this protein kinase in the assembly or regulation of LHCP.
Surface symmetries and PSL2(p)
Date: 2007-05-01
Creator: Murad Özaydin, Charlotte Simmons, Jennifer Taback
Access: Open access
- We classify, up to conjugacy, all orientation-preserving actions of PSL2(p) on closed connected orientable surfaces with spherical quotients. This classification is valid in the topological, PL, smooth, conformal, geometric and algebraic categories and is related to the Inverse Galois Problem. © 2006 American Mathematical Society.
Combinatorial properties of Thompson's group F
Date: 2004-07-01
Creator: Sean Cleary, Jennifer Taback
Access: Open access
- We study some combinatorial consequences of Blake Fordham's theorems on the word metric of Thompson's group F in the standard two generator presentation. We explore connections between the tree pair diagram representing an element w of F, its normal form in the infinite presentation, its word length, and minimal length representatives of it. We estimate word length in terms of the number and type of carets in the tree pair diagram and show sharpness of those estimates. In addition we explore some properties of the Cayley graph of F with respect to the two generator finite presentation. Namely, we exhibit the form of "dead end" elements in this Cayley graph, and show that it has no "deep pockets". Finally, we discuss a simple method for constructing minimal length representatives for strictly positive or negative words.
Bounding the number of cycles of O.D.E.S in Rn
Date: 2001-01-01
Creator: M. Farkas, P. Van Den Driessche, M. L. Zeeman
Access: Open access
- Criteria are given under which the boundary of an oriented surface does not consist entirely of trajectories of the C1 differential equation ẋ = f(x) in Rn. The special case of an annulus is further considered, and the criteria are used to deduce sufficient conditions for the differential equation to have at most one cycle. A bound on the number of cycles on surfaces of higher connectivity is given by similar conditions. ©2000 American Mathematical Society.
String calculation of QCD Wilson loops on arbitrary surfaces
Date: 1995-01-01
Creator: Stephen G. Naculich, Harold A. Riggs
Access: Open access
- Compact string expressions are found for nonintersecting Wilson loops in SU(N) Yang-Mills theory on any surface (orientable or nonorientable) as a weighted sum over covers of the surface. All terms from the coupled chiral sectors of the 1/N expansion of the Wilson loop expectation values are included. © 1995 The American Physical Society.
Ploidy variation in fungi: Polyploidy, aneuploidy, and genome evolution
Date: 2017-07-01
Creator: Robert T. Todd, Anja Forche, Anna Selmecki
Access: Open access
- The ability of an organism to replicate and segregate its genome with high fidelity is vital to its survival and for the production of future generations. Errors in either of these steps (replication or segregation) can lead to a change in ploidy or chromosome number. While these drastic genome changes can be detrimental to the organism, resulting in decreased fitness, they can also provide increased fitness during periods of stress. A change in ploidy or chromosome number can fundamentally change how a cell senses and responds to its environment. Here, we discuss current ideas in fungal biology that illuminate how eukaryotic genome size variation can impact the organism at a cellular and evolutionary level. One of the most fascinating observations from the past 2 decades of research is that some fungi have evolved the ability to tolerate large genome size changes and generate vast genomic heterogeneity without undergoing canonical meiosis.
Identification of SYWKQCAFNAVSCFamide: A broadly conserved crustacean C-type allatostatin-like peptide with both neuromodulatory and cardioactive properties
Date: 2009-04-15
Creator: Patsy S. Dickinson, Teerawat Wiwatpanit, Emily R. Gabranski, Rachel J. Ackerman, Jake S., Stevens, Christopher R. Cashman, Elizabeth A. Stemmler, Andrew E. Christie
Access: Open access
- The allatostatins comprise three structurally distinct peptide families that regulate juvenile hormone production by the insect corpora allata. A-type family members contain the C-terminal motif -YXFGLamide and have been found in species from numerous arthropod taxa. Members of the B-type family exhibit a -WX6Wamide C-terminus and, like the A-type peptides, appear to be broadly conserved within the Arthropoda. By contrast, members of the C-type family, typified by the unblocked C-terminus -PISCF, a pyroglutamine blocked N-terminus, and a disulfide bridge between two internal Cys residues, have only been found in holometabolous insects, i.e. lepidopterans and dipterans. Here, using transcriptomics, we have identified SYWKQCAFNAVSCFamide (disulfide bridging predicted between the two Cys residues), a known honeybee and water flea C-typelike peptide, from the American lobster Homarus americanus (infraorder Astacidea). Using matrix assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS), a mass corresponding to that of SYWKQCAFNAVSCFamide was detected in the H. americanus brain, supporting the existence of this peptide and its theorized structure. Furthermore, SYWKQCAFNAVSCFamide was detected by MALDI-FTMS in neural tissues from five additional astacideans as well as 19 members of four other decapod infraorders (i.e. Achelata, Anomura, Brachyura and Thalassinidea), suggesting that it is a broadly conserved decapod peptide. In H. americanus, SYWKQCAFNAVSCFamide is capable of modulating the output of both the pyloric circuit of the stomatogastric nervous system and the heart. This is the first demonstration of bioactivity for this peptide in any species.
Targeted identification of glycosylated proteins in the gastric pathogen helicobacter pylori (Hp)
Date: 2013-09-01
Creator: Kanokwan Champasa, Scott A. Longwell, Aimee M. Eldridge, Elizabeth A. Stemmler, Danielle H., Dube
Access: Open access
- Virulence of the gastric pathogen Helicobacter pylori (Hp) is directly linked to the pathogen's ability to glycosylate proteins; for example, Hp flagellin proteins are heavily glycosylated with the unusual nine-carbon sugar pseudaminic acid, and this modification is absolutely essential for Hp to synthesize functional flagella and colonize the host's stomach. Although Hp's glycans are linked to pathogenesis, Hp's glycome remains poorly understood; only the two flagellin glycoproteins have been firmly characterized in Hp. Evidence from our laboratory suggests that Hp synthesizes a large number of as-yet unidentified glycoproteins. Here we set out to discover Hp's glycoproteins by coupling glycan metabolic labeling with mass spectrometry analysis. An assessment of the subcellular distribution of azide-labeled proteins by Western blot analysis indicated that glycoproteins are present throughout Hp and may therefore serve diverse functions. To identify these species, Hp's azide-labeled glycoproteins were tagged via Staudinger ligation, enriched by tandem affinity chromatography, and analyzed by multidimensional protein identification technology. Direct comparison of enriched azide-labeled glycoproteins with a mock-enriched control by both SDS-PAGE and mass spectrometry-based analyses confirmed the selective enrichment of azide-labeled glycoproteins. We identified 125 candidate glycoproteins with diverse biological functions, including those linked with pathogenesis. Mass spectrometry analyses of enriched azide-labeled glycoproteins before and after cleavage of O-linked glycans revealed the presence of Staudinger ligation-glycan adducts in samples only after beta-elimination, confirming the synthesis of O-linked glycoproteins in Hp. Finally, the secreted colonization factors urease alpha and urease beta were biochemically validated as glycosylated proteins via Western blot analysis as well as by mass spectrometry analysis of cleaved glycan products. These data set the stage for the development of glycosylation-based therapeutic strategies, such as new vaccines based on natively glycosylated Hp proteins, to eradicate Hp infection. Broadly, this report validates metabolic labeling as an effective and efficient approach for the identification of bacterial glycoproteins. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.
Increasing forest loss worldwide from invasive pests requires new trade regulations
Date: 2014-10-01
Creator: Bitty A. Roy, Helen M. Alexander, Jennifer Davidson, Faith T. Campbell, Jeremy J., Burdon, Richard Sniezko, Clive Brasier
Access: Open access
- Loss of forests due to non-native invasive pests (including insects, nematodes, and pathogens) is a global phenomenon with profound population, community, ecosystem, and economic impacts. We review the magnitude of pest-associated forest loss worldwide and discuss the major ecological and evolutionary causes and consequences of these invasions. After compiling and analyzing a dataset of pest invasions from 21 countries, we show that the number of forest pest invasions recorded for a given country has a significant positive relationship with trade (as indicated by gross domestic product) and is not associated with the amount of forested land within that country. We recommend revisions to existing international protocols for preventing pest entry and proliferation, including prohibiting shipments of non-essential plants and plant products unless quarantined. Because invasions often originate from taxa that are scientifically described only after their introduction, current phytosanitary regulations - which target specific, already named organisms - Are ineffective.