Browsing by Subject "translation"
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Item Breakup of a liquid jet(2019-10-20) Weber, ConstantinThe breakup phenomena (drop and wave formation) which can be observed at moderate velocities were investigated theoretically. Rotation-symmetric disturbances lead to drop formation. The breakup time is constant for every liquid and jet thickness at low velocities; the breakup length increases with the velocity. Wave formation is explained by the influence of aerodynamic forces and theoretical laws are derived which agree in character with the experiments.Item Cloning of wheat germ eukaryotic initiation factor eIF2(2009) Parekh, Priyanka; Karen BrowningEukaryotic Initiation Factor 2 (eIF2) is a protein complex found in eukaryotes involved in the initiation of translation. eIF2 consists of three non-identical subunits (α, β, and γ) and is required for the translation of virtually all mRNA transcripts. eIF2 forms a ternary complex with GTP and Met-tRNAi Met, which then associates with the 40S ribosomal subunit. This 43S preinitiation complex scans the mRNA transcript for the AUG initiation codon, at which time eIF2’s GTP is hydrolyzed to GDP and eIF2-GDP dissociates from the 40S subunit. A guanine nucleotide exchange factor called eIF2B is required to reform eIF2-GTP, which can now facilitate a new round of translation initiation. In many eukaryotic systems, eIF2 has been documented as a site of regulation of translation via phosphorylation at a conserved serine residue on the α subunit. These studies have found that phosphorylated eIF2 (eIF2[αP]) binds eIF2B with a much higher affinity than non-phosphorylated eIF2. Since eIF2B is typically present at less than half the cellular concentration of eIF2, the result of this strong binding is sequestration of eIF2B and inhibition of its nucleotide exchange activity. Because only eIF2-GTP can bind Met-tRNAi Met, the result is inhibition of eIF2’s ternary complex formation, and thus inhibition of protein synthesis. Most studies exploring this mechanism of translational control have focused on yeast and mammalian systems. However, in higher plants, regulation of translation by phosphorylation of eIF2α has not been shown to occur in vivo to date. Although homologous genes of all five eIF2B subunits have been identified in plants, the eIF2B protein complex has not yet been isolated from plants. Similarly, though a gene with homology to an eIF2α-kinase from yeast (gcn2) has been identified in plants, phosphorylation of eIF2 in a plant translational lysate system has not yet been shown to inhibit translation. The difference of the binding affinity of eIF2 for GDP and GTP is not nearly as severe as that found in other eukaryotic systems, suggesting that a recycling factor (eIF2B) and phosphorylation of eIF2α may play a less critical regulatory role in plants. There are significant differences between plants and animals in their responses to environmental stress, and therefore methods of translational regulation may also be different. In order to explore the extent of regulation via phosphorylation of eIF2α in plants, and to uncover other plant-specific regulation on eIF2, it is necessary to be able to express the eIF2 complex in a manipulable bacterial system. This will allow mutagenesis of the three subunits to probe structure and function. This thesis reports the use of recombinant methods to construct a single expression vector containing all three genes of eIF2 from T. aestivum (wheat), with the goal of subsequent expression of eIF2α, β, and γ as a functional complex in E. coli.Item "A Community Unlike Any Other": Incorporating Fansubbers into Corporate Capitalism on Viki.com(2018-05) Woodhouse, TayloreViki.com, founded in 2008, is a streaming site that offers Korean (and other East Asian) television programs with subtitles in a variety of languages. Unlike other K-drama distribution sites that serve audiences outside of South Korea, Viki utilizes fan-volunteers, called fansubbers, as laborers to produce its subtitles. Fan subtitling and distribution of foreign language media in the United States is a rich fan practice dating back to the 1980s, and Viki is the first corporate entity that has harnessed the productive power of fansubbers. In this thesis, I investigate how Viki has been able to capture the enthusiasm and productive capacity of fansubbers. Particularly, I examine how Viki has been able to monetize fansubbing in while still staying competitive with sites who employee trained, professional translators. I argue that Viki has succeeded in courting fansubbers as laborers by co-opting the concept of the “fan community.” I focus on how Viki strategically speaks about the community and builds its site to facilitate the functioning of its community so as to encourage fansubbers to view themselves as semi-professional laborers instead of amateur fans. In reframing the role of the fansubbing community, Viki creates a new image for what being a fansubber means and why fansubbing is valuable that emphasizes creating value for Viki over creating value for the fan community.Item Expression and purification of recombinant wheat translation initiation factor eIF2(2010) Tzeng, Shinetin; Karen BrowningProteins carry out the activities for cellular growth and maintenance in a timely and space-specific manner, so the formation of proteins from their genetic counterparts, or translation, must be tightly controlled. Regulation occurs primarily during the initiation step of translation, a highly involved process that properly positions messenger RNA, methionine-charged initiator transfer RNA, and ribosomes via a family of proteins known as eukaryotic initiation factors (eIFs). One of these proteins is eIF2, a trimeric complex made of eIF2α, eIF2β, and eIF2γ. In mammalian and yeast systems, the phosphorylation of eIF2α by specific kinases and its downstream effects down-regulate global protein synthesis, and the mechanism has been widely studied. However, in plants, evidence suggests that different regulatory pathways may be involved. To ultimately describe the molecular and biochemical basis by which higher plants regulate protein synthesis, studies of mutant eIF2α and the effects of phosphorylation are necessary. To achieve this goal, genes for the three subunits of wheat eIF2 were synthesized de novo by overlapping oligonucleotides that were optimized for E. coli codon usage, and then the genes were cloned into an operon for expression of the complex in E. coli. This particular study focuses on optimizing the conditions for expression and purification of soluble eIF2 complexes. Alterations in the strain of E. coli, growth condition and media, and operon construct were tested to enhance eIF2 expression and solubility, and different methods of purification were applied. However, at this point, the expression and purification of eIF2 still remains unsuccessful.Item The Foreign Language Teachers' Bulletin(University of Texas at Austin, 1914-05-20) University of Texas at AustinItem The formation of drops by nozzles and the breakup of liquid jets(2019-10-20) Ohnesorge, Wolfgang vonShows by means of high-speed motion pictures that the breakup of a jet passes successively through three phases (breakup according to Rayleigh — breakup according to Weber-Haenlein — atomization), and that the transition from one phase to the next occurs at increasing higher Reynolds No's. as a function of a dimensionless term, containing viscosity, surface tension, density, and orifice diameter Z = η / √(σ ρ d) where η is the absolute viscosity, σ is the surface tension, ρ is the density and d is the orifice diameter.Item Impaired Dendritic Expression and Plasticity Of H-Channels in the fmr1(-/Y) Mouse Model of Fragile X Syndrome(2012-03) Brager, Darrin H.; Akhavan, Arvin R.; Johnston, Daniel; Brager, Darrin H.; Akhavan, Arvin R.; Johnston, DanielDespite extensive research into both synaptic and morphological changes, surprisingly little is known about dendritic function in fragile X syndrome (FXS). We found that the dendritic input resistance of CA1 neurons was significantly lower in fmr1(-/y) versus wild-type mice. Consistent with elevated dendritic I-h, voltage sag, rebound, and resonance frequency were significantly higher and temporal summation was lower in the dendrites of fmr1(-/y) mice. Dendritic expression of the h-channel subunit HCN1, but not HCN2, was higher in the CA1 region of fmr1(-/y) mice. Interestingly, whereas mGluR-mediated persistent decreases in Ih occurred in both wildtype and fmr1(-/y) mice, persistent increases in Ih that occurred after LTP induction in wild-type mice were absent in fmr1(-/y) mice. Thus, chronic upregulation of dendritic Ih in conjunction with impairment of homeostatic h-channel plasticity represents a dendritic channelopathy in this model of mental retardation and may provide a mechanism for the cognitive impairment associated with FXS.Item Influence of the Ratio Between the Translation and Contra-Rotating Coating Mechanism on Different Laser Sintering Materials and Their Packing Density(University of Texas at Austin, 2017) Meyer, L.; Wegner, A.; Witt, G.An initial study about the advanced machine parameters and their impact on the packing density of different laser sintering materials was conducted on a self-developed laser sintering machine. Usually, on commercial machines, the ratio between the translational and contra-rotatory movement of the roller is fixed. The standard ratio is established for polyamide 12, but new materials, such as polyamide 6 or polybutylene terephthalate, need adjustable parameters to find optimized composition coating results. In the testing machine, the contra rotating roller can be replaced by a coating blade to generate the powder layers. In Addition to the tests with the roller, two different shapes of coating blades were tested. This allows a comparison between both commercial coating systems in laser sintering machines.Item Letter From Emmett L. Bennett Jr. to Thomas G. Palaima, May 17, 1985(1985-05-17) Bennett, Emmett L., Jr.Item Letter to A. Azzaroli from H.B. Stenzel on 1963-06-20(1963-06-20) Stenzel, Henryk B.Item Letter to H.B. Stenzel from Jean Lewis on 1948-08-26(1948-08-26) Lewis, JeanItem Letter to H.B. Stenzel from M.K. Elias on 1946-02-18(1946-02-18) Elias, Maxim K.Item Letter to H.B. Stenzel from M.K. Elias on 1946-02-20(1946-02-20) Elias, Maxim K.Item Letter to H.B. Stenzel from M.K. Elias on 1946-03-07(1946-03-07) Elias, Maxim K.Item Letter to H.B. Stenzel from M.K. Elias on 1949-01-21(1949-01-21) Elias, Maxim K.Item Letter to H.B. Stenzel from M.K. Elias on 1962-01-01(1962-01-01) Elias, Maxim K.Item Letter to H.B. Stenzel from M.K. Stenzel on 1946-04-20(1946-04-20) Stenzel, M.K.Item Letter to H.B. Stenzel from Raymond C. Moore on 1961-07-05(1961-07-05) Moore, Raymond C.Item Letter to H.B. Stenzel from Roger B. Williams on 1968-06-14(1968-06-14) Williams, Roger B.Item Letter to Henryk B. Stenzel from Raymond C. Moore on 1970-05-01(1970-05-01) Moore, Raymond C.