Showing 2821 - 2830 of 5707 Items
That’s DOPE: the delayed-onset, prolonged excitation response of a primary auditory interneuron in Gryllus bimaculatus This record is embargoed.
- Embargo End Date: 2025-05-13
Date: 2020-01-01
Creator: Samuel G. Brill-Weil
Access: Embargoed
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.
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.
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.
Accurate transcription of truncated ribosomal DNA templates in a Drosophila cell-free system
Date: 1982-01-01
Creator: B. D. Kohorn, P. M.M. Rae
Access: Open access
- An extract of Drosophila melanogaster Kc cells is shown to give specific and accurate transcription of truncated segments of cloned D. melanogaster ribosomal DNA (rDNA). When clones are digested with restriction enzymes so that the initiation site is flanked by 0.3 kilobase (kb) of nontranscribed spacer and >0.4 kb of external transcribed spacer, RNA polymerase I activity in the extract parallels in vivo rRNA synthesis in selection of the coding strand of template and the site of transcription initiation. When >0.3 kb of the nontranscribed spacer is contiguous with transcribed spacer, in vitro initiations evidently also occur in repeated sequences adjacent to the site of in vivo initiation; when ≤0.4 kb of the external transcribed spacer is present in a segment, expected transcripts are heterogeneous in length or not detectable. Transcription in the cell-free system requires the specific addition of D. melanogaster rDNA: neither D. virilis rDNA, vector plasmid, nor clones of D. melanogaster genes that are transcribed in vivo by RNA polymerases II and III serve as templates in the system. Drosophila rDNA units that have an interruption in the 28S rRNA coding region are not transcribed in vivo, but restriction digests of a recombinant phage DNA that contains such a unit are active as template for in vitro rDNA transcription.
Transient phenomena in ecology
Date: 2018-09-07
Creator: Alan Hastings, Karen C. Abbott, Kim Cuddington, Tessa Francis, Gabriel, Gellner, Ying Cheng Lai
Access: Open access
- The importance of transient dynamics in ecological systems and in the models that describe them has become increasingly recognized. However, previous work has typically treated each instance of these dynamics separately. We review both empirical examples and model systems, and outline a classification of transient dynamics based on ideas and concepts from dynamical systems theory. This classification provides ways to understand the likelihood of transients for particular systems, and to guide investigations to determine the timing of sudden switches in dynamics and other characteristics of transients. Implications for both management and underlying ecological theories emerge.
Bowdoin College - Medical School of Maine Catalogue (1910-1911)
Date: 1911-01-01
Access: Open access
- Bowdoin College Bulletin no. 31
Atmospheric O2/N2 changes, 1993-2002: Implications for the partitioning of fossil fuel CO2 sequestration
Date: 2005-12-01
Creator: Michael L. Bender, David T. Ho, Melissa B. Hendricks, Robert Mika, Mark O., Battle, Pieter P. Tans, Thomas J. Conway, Blake Sturtevant, Nicolas Cassar
Access: Open access
- Improvements made to an established mass spectrometric method for measuring changes in atmospheric O2/N2 are described. With the improvements in sample handling and analysis, sample throughput and analytical precision have both increased. Aliquots from duplicate flasks are repeatedly measured over a period of 2 weeks, with an overall standard error in each flask of 3-4 per meg, corresponding to 0.6-0.8 ppm O2 in air. Records of changes in O2/N2 from six global sampling stations (Barrow, American Samoa, Cape Grim, Amsterdam Island, Macquarie Island, and Syowa Station) are presented. Combined with measurements Of CO2 from the same sample flasks, land and ocean carbon uptake were calculated from the three sampling stations with the longest records (Barrow, Samoa, and Cape Grim). From 1994-2002, We find the average CO2 uptake by the ocean and the land biosphere was 1.7 ± 0.5 and 1.0 ± 0.6 GtC yr -1 respectively; these numbers include a correction of 0.3 Gt C yr-l due to secular outgassing of ocean O2. Interannual variability calculated from these data shows a strong land carbon source associated with the 1997-1998 El Niño event, supporting many previous studies indicating that high atmospheric growth rates observed during most El Niño events reflect diminished land uptake. Calculations of interannual variability in land and ocean uptake are probably confounded by non-zero annual air sea fluxes of O2. The origin of these fluxes is not yet understood. Copyright 2005 by the American Geophysical Union.
Survival Strategies: Historic Preservation, Jewish Community, and the German Democratic Republic
Date: 2020-01-01
Creator: Emily Ann Cohen
Access: Open access
- Following the Second World War, as German Communists worked to establish a new socialist East German state, Jews who survived persecution and imprisonment by the Nazis worked to reestablish a Jewish community at the same time. Though many scholars dismiss the relationship between Jews and the Socialist Unity Party, the ruling party of the German Democratic Republic, as one characterized only by neglect and occasional political exploitation, it was much more nuanced, shaped in large part by the Cold War. Both the party and the Jewish community relied on the other to accomplish their goals, namely, survival in a new world order: The Socialist Unity Party relied on the Jewish community to maintain the German Democratic Republic's claim to legitimacy, and the Jews, few in number, relied on the party for financial support. Despite mutual benefits, however, the state and party nearly always had the upper hand. The power imbalance led Jews to find creative ways to fulfill their needs and, at several points, even prompted protest of the party’s treatment of its Jewish citizens. This paper follows the course of this relationship by focusing on the German Democratic Republic's management of sites of historical significance—which vacillated between outright destruction and dedicated protection—returning particularly to the Jewish cemetery in Berlin-Weissensee, one of the largest Jewish cemeteries in Europe. With this particular lens, this project addresses questions about memory, mythology, and agency in a socialist dictatorship and challenges assumptions about Jewish life in East Germany.