Showing 961 - 970 of 2040 Items
A genomewide survey argues that every zygotic gene product is dispensable for the initiation of somatic homolog pairing in Drosophila
Date: 2008-11-01
Creator: Jack R. Bateman
C. Ting Wu
Access: Open access
- Studies from diverse organisms show that distinct interchromosomal interactions are associated with many developmental events. Despite recent advances in uncovering such phenomena, our understanding of how interchromosomal interactions are initiated and regulated is incomplete. During the maternal-to-zygotic transition (MZT) of Drosophila embryogenesis, stable interchromosomal contacts form between maternal and paternal homologous chromosomes, a phenomenon known as somatic homolog pairing. To better understand the events that initiate pairing, we performed a genomewide assessment of the zygotic contribution to this process. Specifically, we took advantage of the segregational properties of compound chromosomes to generate embryos lacking entire chromosome arms and, thus, all zygotic gene products derived from those arms. Using DNA fluorescence in situ hybridization (FISH) to assess the initiation of pairing at five separate loci, this approach allowed us to survey the entire zygotic genome using just a handful of crosses. Remarkably, we found no defect in pairing in embryos lacking any chromosome arm, indicating that no zygotic gene product is essential for pairing to initiate. From these data, we conclude that the initiation of pairing can occur independently of zygotic control and may therefore be part of the developmental program encoded by the maternal genome. Copyright © 2008 by the Genetics Society of America.
Site-specific transformation of Drosophila via φC31 integrase-mediated cassette exchange
Date: 2006-06-30
Creator: Jack R. Bateman
Anne M. Lee
C. Ting Wu
Access: Open access
- Position effects can complicate transgene analyses. This is especially true when comparing transgenes that have inserted randomly into different genomic positions and are therefore subject to varying position effects. Here, we introduce a method for the precise targeting of transgenic constructs to predetermined genomic sites in Drosophila using the φC31 integrase system in conjunction with recombinase-mediated cassette exchange (RMCE). We demonstrate the feasibility of this system using two donor cassettes, one carrying the yellow gene and the other carrying GFP. At all four genomic sites tested, we observed exchange of donor cassettes with an integrated target cassette carrying the mini-white gene. Furthermore, because RMCE-mediated integration of the donor cassette is necessarily accompanied by loss of the target cassette, we were able to identify integrants simply by the loss of mini-white eye color. Importantly, this feature of the technology will permit integration of unmarked constructs into Drosophila, even those lacking functional genes. Thus, φC31 integrase-mediated RMCE should greatly facilitate transgene analysis as well as permit new experimental designs. Copyright © 2006 by the Genetics Society of America.
Υ(1S)→γ+noninteracting particles
Date: 1995-01-01
Creator: R. Balest
K. Cho
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
H. A. Cho
D. M. Coffman
D. S. Crowcroft
P. S. Drell
D. Dumas
R. Ehrlich
P. Gaidarev
R. S. Galik
M. Garcia-Sciveres
B. Geiser
B. Gittelman
S. W. Gray
D. L. Hartill
B. K. Heltsley
S. Henderson
C. D. Jones
S. L. Jones
Access: Open access
- We consider the decay of Υ(1S) particles produced at CESR into a photon which is observed by the CLEO detector plus particles which are not seen. These could be real particles which fall outside of our acceptance, or particles which are noninteracting. We report the results of our search fo the process Υ(1S)→γ+''unseen'' for photon energies >1 GeV, obtaining limits for the case where ''unseen'' is either a single particle or a particle-antiparticle pair. Our upper limits represent the highest sensitivity measurements for such decays to date. © 1995 The American Physical Society.
The role of adjuvant in mediating antigen structure and stability
Date: 2012-01-01
Creator: Latoya Jones Braun
Aimee M. Eldridge
Jessica Cummiskey
Kelly K. Arthur
Deborah S., Wuttke
Access: Open access
- The purpose of this study was to probe the fate of a model antigen, a cysteine-free mutant of bacteriophage T4 lysozyme, to the level of fine structural detail, as a consequence of its interaction with an aluminum (Al)-containing adjuvant. Fluorescence spectroscopy and differential scanning calorimetry were used to compare the thermal stability of the protein in solution versus adsorbed onto an Al-containing adjuvant. Differences in accessible hydrophobic surface areas were investigated using an extrinsic fluorescence probe, 8-Anilino-1-naphthalenesulfonic acid (ANS). As has been observed with other model antigens, the apparent thermal stability of the protein decreased following adsorption onto the adjuvant. ANS spectra suggested that adsorption onto the adjuvant caused an increase in exposure of hydrophobic regions of the protein. Electrostatic interactions drove the adsorption, and disruption of these interactions with high ionic strength buffers facilitated the collection of two-dimensional 15N heteronuclear single quantum coherence nuclear magnetic resonance data of protein released from the adjuvant. Although the altered stability of the adsorbed protein suggested changes to the protein's structure, the fine structure of the desorbed protein was nearly identical to the protein's structure in the adjuvant-free formulation. Thus, the adjuvant-induced changes to the protein that were responsible for the reduced thermal stability were not observed upon desorption. © 2011 Wiley Periodicals, Inc.
Measurement of the branching fraction for γ (1S) → τ+τ-
Date: 1994-12-01
Creator: D. Cinabro
T. Liu
M. Saulnier
R. Wilson
H., Yamamoto
T. Bergfeld
B. I. Eisenstein
G. Gollin
B. Ong
M. Palmer
M. Selen
J. J. Thaler
K. W. Edwards
M. Ogg
A. Bellerive
D. I. Britton
E. R.F. Hyatt
D. B. MacFarlane
P. M. Patel
B. Spaan
A. J. Sadoff
R. Ammar
P. Baringer
A. Bean
D. Besson
D. Coppage
N. Copty
R. Davis
N. Hancock
M. Kelly
S. Kotov
Access: Open access
- We have studied the leptonic decay of the γ (1S) resonance into tau pairs using the CLEO II detector. A clean sample of tau pair events is identified via events containing two charged particles where exactly one of the particles is an identified electron. We find B(γ(1S) → τ+τ-) = (2.61±0.12-0.13+0.09)%. The result is consistent with expectations from lepton universality. © 1994.
Context-dependent protein stabilization by methionine-to-leucine substitution shown in T4 lysozyme
Date: 1998-01-01
Creator: Leigh Ann Lipscomb
Nadine C. Gassner
Sheila D. Snow
Aimee M. Eldridge
Walter A., Baase
Devin L. Drew
Brian W. Matthews
Access: Open access
- The substitution of methionines with leucines within the interior of a protein is expected to increase stability both because of a more favorable solvent transfer team as well as the reduced entropic cost of holding a leucine side chain in a defined position. Together, these two terms are expected to contribute about 1.4 kcal/mol to protein stability for each Met → Leu substitution when fully buried. At the same time, this expected beneficial effect may be offset by steric factors due to differences in the shape of leucine and methionine. To investigate the interplay between these factors, all methionines in T4 lysozyme except at the amino-terminus were individually replaced with leucine. Of these mutants, M106L and M120L have stabilities 0.5 kcal/mol higher than wild-type T4 lysozyme, while M6L is significantly destabilized (-2.8 kcal/mol). M102L, described previously, is also destabilized (-0.9 kcal/mol). Based on this limited sample it appears that methionine-to-leucine substitutions can increase protein stability but only in a situation where the methionine side chain is fully or partially buried, yet allows the introduction of the leucine without concomitant steric interference. The variants, together with methionine-to-lysine substitutions at the same sites, follow the general pattern that substitutions at rigid, internal sites tend to be most destabilizing, whereas replacements at more solvent-exposed sites are better tolerated.
A measurement of B(D+S → φl+ν) B(D+S → φπ+)
Date: 1994-03-31
Creator: F. Butler
X. Fu
G. Kalbfleisch
W. R. Ross
P., Skubic
J. Snow
P. L. Wang
M. Wood
D. N. Brown
J. Fast
R. L. McIlwain
T. Miao
D. H. Miller
M. Modesitt
D. Payne
E. I. Shibata
I. P.J. Shipsey
P. N. Wang
M. Battle
J. Ernst
Y. Kwon
S. Roberts
E. H. Thorndike
C. H. Wang
J. Dominick
M. Lambrecht
S. Sanghera
V. Shelkov
T. Skwarnicki
R. Stroynowski
I. Volobouev
Access: Open access
- Using the CLEO II detector at CESR, we have measured the ratio of branching fractions B(D+S → φl+ν) B(D+S → φπ+) = 0.54 ± 0.05 ± 0.04. We use this measurement to obtain a model dependent estimate of B(D+S → φπ+). © 1994.
Bubbles & Bought-Ins: Reevaluating Price Movements in the Art Market
Date: 2020-01-01
Creator: Silas Wuerth
Access: Open access
- Employs two tests for bubbles in the art market. First, a right-hand forward recursive augmented Dickey-Fuller test to identify explosive price movements. Second, a test for the statistical significance of hedonic regression price index coefficients after controlling for equity market performance. Finds strong evidence for a speculative bubble in the pre-Great Recession "Post-War & Contemporary" market. Evidence for this bubble diminishes but does not dissipate after accounting for the effect of failed sales on index returns.
A Bayesian hierarchical mixture model with continuous-time Markov chains to capture bumblebee foraging behavior
Date: 2021-01-01
Creator: Max Thrush Hukill
Access: Open access
- The standard statistical methodology for analyzing complex case-control studies in ethology is often limited by approaches that force researchers to model distinct aspects of biological processes in a piecemeal, disjointed fashion. By developing a hierarchical Bayesian model, this work demonstrates that statistical inference in this context can be done using a single coherent framework. To do this, we construct a continuous-time Markov chain (CTMC) to model bumblebee foraging behavior. To connect the experimental design with the CTMC, we employ a mixture model controlled by a logistic regression on the two-factor design matrix. We then show how to infer these model parameters from experimental data using Markov chain Monte Carlo and interpret the results from a motivating experiment.
Narrative painting and visual gossip at the early-twentieth-century royal academy
Date: 2009-06-01
Creator: Pamela Fletcher
Access: Open access
- Narrative paintings of modern life were immensely popular at the Royal Academy from the 1850s well into the early twentieth century. Perfectly suited to the Academy's culture of conversation, the pictures invited viewers to respond to the scenes as if they were real life situations, and gossip about the depicted characters as if they were real people. While such responses were routinely derided by critics as evidence of the public's lack of aesthetic sophistication, they offer tantalizing glimpses of the pictures' social lives. This article argues that taking gossip seriously as a mode of engagement with art both amplifies our understanding of the meanings, functions, and pleasures of narrative painting, and suggests specific connections between exhibition culture and the meanings of pictures. Using the richly documented reception of the 'problem pictures' of the 1910s and 1920s as the primary evidence, this article establishes a taxonomy of gossipy modes of engagement with narrative painting, and argues that gossiping about pictures allowed for the performance of individual identity, the creation of social and artistic groups, and connected public and private understandings of the world.