Showing 1451 - 1460 of 2040 Items
Erratum: Context-dependent protein stabilization by methionine-to- leucine substitution shown in T4 lysozyme (Protein Science (November 3, 1998) 7:3 (772))
Date: 1998-01-01
Creator: L. A. Lipscomb
N. C. Gassner
S. D. Snow
A. M. Eldridge
W. A., Baase
D. L. Drew
B. W. Matthews
Access: Open access
Semileptonic branching fractions of charged and neutral B mesons
Date: 1994-01-01
Creator: M. Athanas
W. Brower
G. Masek
H. P. Paar
J., Gronberg
R. Kutschke
S. Menary
R. J. Morrison
S. Nakanishi
H. N. Nelson
T. K. Nelson
C. Qiao
J. D. Richman
A. Ryd
H. Tajima
D. Sperka
M. S. Witherell
R. Balest
K. Cho
W. T. Ford
D. R. Johnson
K. Lingel
M. Lohner
P. Rankin
J. G. Smith
J. P. Alexander
C. Bebek
K. Berkelman
K. Bloom
T. E. Browder
D. G. Cassel
Access: Open access
- An examination of leptons in (4S) events tagged by reconstructed B meson decays yields semileptonic branching fractions of b-=(10.1±1.8±1. 5)% for charged and b0=(10.9±0.7±1.1)% for neutral B mesons. This is the first measurement for charged B mesons. Assuming equality of the charged and neutral semileptonic widths, the ratio b-b0=0.93±0.18±0.12 is equivalent to the ratio of lifetimes. © 1994 The American Physical Society.
Mitochondrial genotype influences the response to cold stress in the European green crab, Carcinus maenas
Date: 2019-01-01
Creator: Aidan F. Coyle
Erin R. Voss
Carolyn K. Tepolt
David B. Carlon
Access: Open access
- Hybrid zones provide natural experiments in recombination within and between genomes that may have strong effects on organismal fitness. On the East Coast of North America, two distinct lineages of the European green crab (Carcinus maenas) have been introduced in the last two centuries. These two lineages with putatively different adaptive properties have hybridized along the coast of the eastern Gulf of Maine, producing new nuclear and mitochondrial combinations that show clinal variation correlated with water temperature. To test the hypothesis that mitochondrial or nuclear genes have effects on thermal tolerance, we first measured the response to cold stress in crabs collected throughout the hybrid zone, then sequenced the mitochondrial CO1 gene and two nuclear single nucleotide polymorphisms (SNPs) representative of nuclear genetic lineage. Mitochondrial haplotype had a strong association with the ability of crabs to right themselves at 4.5°C that was sex specific: haplotypes originally from northern Europe gave male crabs an advantage while there was no haplotype effect on righting in female crabs. By contrast, the two nuclear SNPs that were significant outliers in a comparison between northern and southern C. maenas populations had no effect on righting response at low temperature. These results add C. maenas to the shortlist of ectotherms in which mitochondrial variation has been shown to affect thermal tolerance, and suggest that natural selection is shaping the structure of the hybrid zone across the Gulf of Maine. Our limited genomic sampling does not eliminate the strong possibility that mito-nuclear co-adaptation may play a role in the differences in thermal phenotypes documented here. Linkage between mitochondrial genotype and thermal tolerance suggests a role for local adaptation in promoting the spread of invasive populations of C. maenas around the world.
From Left to Right? White Evangelical Politicization, GOP Incorporation, and the Effect of Party Affiliation on Group Opinion Change
Date: 2013-05-01
Creator: Devon B Shapiro
Access: Open access
- While most white evangelicals in America have advocated moral, cultural, and social conservatism since the Founding, the group’s fiscal and social welfare preferences have been more volatile. Early 20th century evangelicals tended to be socially conservative, fiscally liberal, and, to the extent that they were politicized, mostly Democratic partisans. Since that time, not only have white evangelicals abandoned the Democratic Party, but also they have largely become fiscal and social welfare conservatives. I attempt to explain that transformation. I first examine the dynamics of white evangelical politicization and GOP incorporation, providing social and historical context to the political and partisan calculations of white evangelicals since the 1970s. Further, I propose a party affiliation effect that helps to explain white evangelical fiscal and social welfare conservatism. This effect asserts that partisanship penetrates individual conceptions of political issues. In the case of white evangelicals, I argue that the group affiliated with the GOP largely on the basis of socio-moral issues and concerns. Partly as a result of that affiliation, group opinion on fiscal policy began to drift to the right, toward the Republican Party status quo. Consistent with this claim, I provide longitudinal analyses of ANES and GSS data that shed light on the timing of opinion changes. As we would expect, white evangelical opinion on economic issues was closer to Democratic partisans during the 1960s and moved moved toward Republicans during the 1980s-1990s.
Bodies, Memories, Ghosts, and Objects or Telling a Memory
Date: 2023-01-01
Creator: Natsumi Lynne Meyer
Access: Open access
- I think it started in December 2017, when my Mama sent me to Japan to take care of my grandparents, Baba and Jiji, alone. I had been to Japan almost every year since I was eleven years old, and several times before that too, but this was my first time without Mama. When Mama was there, Japan was filtered through her. I could poke bits of myself through her editing and approval. I could read street signs because of the way she read them, and I could understand my grandparents’ sighs from the timbre of her translation. That December, though, I had to see and hear alone. The tiny shakes in Baba’s legs and the indentation in Jiji’s forehead from when he fell down the stairs crystallized in my memory, and I had to write about it. This project includes a series of creative nonfiction and fiction pieces centered around telling my family stories. Writing from interviews, observations, and generational memories, I weave together these story fragments to discuss Asian American identity and immigration, WWII trauma, aging, and inheritance.
Wall-associated kinases are expressed throughout plant development and are required for cell expansion
Date: 2001-01-01
Creator: T. A. Wagner
B. D. Kohorn
Access: Open access
- The mechanism by which events in the angiosperm cell wall are communicated to the cytoplasm is not well characterized. A family of five Arabidopsis wall-associated kinases (WAKs) have the potential to provide a physical and signaling continuum between the cell wall and the cytoplasm. The WAKs have an active cytoplasmic protein kinase domain, span the plasma membrane, and contain an N terminus that binds the cell wall. We show here that WAKs are expressed at organ junctions, in shoot and root apical meristems, in expanding leaves, and in response to wall disturbances. Leaves expressing an antisense WAK gene have reduced WAK protein levels and exhibit a loss of cell expansion. WAKs are covalently bound to pectin in the cell wall, providing evidence that the binding of a structural carbohydrate by a receptor-like kinase may have significance in the control of cell expansion.
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.
Hydrophobic core but not amino-terminal charged residues are required for translocation of an integral thylakoid membrane protein in vivo
Date: 1996-10-07
Creator: Benoit Baillet
Bruce D. Kohorn
Access: Open access
- The integral membrane protein cytochrome f contains an amino-terminal signal sequence that is required for translocation into the thylakoid membrane. The signal sequence contains a hydrophobic core neighbored by an amino-terminal charged residue. Mutations that introduce charged amino acids into the hydrophobic core are inhibitory to cytochrome f translocation, and thus render cells non-photosynthetic. We have isolated both nuclear and chloroplast suppressors of these mutations by selecting for restoration of photosynthetic growth of Chlamydomonas. Here we describe the characterization of two chloroplast, second site suppressor mutations. Both suppressors remove the positively charged amino acid that borders the amino terminus of the hydrophobic core, and replace this arginine with either a cysteine or a leucine. The existence of these suppressors suggests that the hydrophobic core can be shifted in position within the signal sequence, and analysis of triple mutants in the signal confirms this hypothesis. Thus this signal that mediates translocation into the thylakoid membrane is characterized by a hydrophobic region whose exact amino acid content is not critical, and that need not be flanked on its amino terminus by a charged residue.
A cell wall-associated, receptor-like protein kinase
Date: 1996-09-05
Creator: Zheng Hui He
Masaaki Fujiki
Bruce D. Kohorn
Access: Open access
- Physical connections between higher plant cell walls and the plasma membrane have been identified visually, but the molecules involved in the contact are unknown. We describe here an Arabidopsis thaliana protein kinase, designated Wak1 for wall-associated kinase, whose predicted extracytoplasmic domain contains several epidermal growth factor repeats and identity with a viral movement protein. Wak1 fractionates with insoluble material when plant tissue is ground in a variety of buffers and detergents, suggesting a tight association with the plant extracellular matrix. Immunocytochemistry confirms that Wak1 is associated with the cell wall. Enzymatic digestion of the cell wall allows the release of Wak1 from the insoluble cell wall fraction, and protease experiments indicate that Wak1 likely has a cytoplasmic kinase domain, and the EGF containing domain is extracellular. Wak1 is found in all vegetative tissues of Arabidopsis, and has relatives in other angiosperms, but not Chlamydomonas. We suggest that Wak1 is a good candidate for a physical continuum between the cell wall and the cytoplasm, and since the kinase is cytoplasmic, it also has the potential to mediate signals to the cytoplasm from the cell wall.
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.