1,119 research outputs found
The Impacts of GM Seed Technology on Cotton: Cost of Production in Mississippi, 1996 - 2005
Genetically modified (GM) cotton varieties have changed many aspects of cotton production in the United States. The rapid adoption of GM cotton varieties in Mississippi has allowed producers to alter certain production practices because of added benefits gained from GM varieties. This study analyses some of the effects of certain changes in some of the most relevant components of cotton production on yield that stem from the adoption of GM varieties in Mississippi by comparing production functions from 1996 and 2005.Mississippi cotton production, Genetically Modified cotton varieties, structural change, production function., Crop Production/Industries,
Gene expression patterns in heterozygous Plk4 murine embryonic fibroblasts
<p>Abstract</p> <p>Background</p> <p>The polo-like kinases (Plks) are a group of serine/threonine kinases which have roles in many aspects of cellular function including the regulation of mitotic activity and cellular stress responses. This study focuses on Plk4, the most divergent member of the Plk family, which is necessary for proper cellular proliferation. More specifically, alterations in Plk4 levels cause significantly adverse mitotic defects including abnormal centrosome duplication and aberrant mitotic spindle formation. We sought to clarify the effect of reduced Plk4 levels on the cell by examining transcript profiles of <it>Plk4 </it>wild-type and heterozygous mouse embryonic fibroblasts (MEFs). Subsequently, the levels of several key proteins involved in the DNA damage response were examined.</p> <p>Results</p> <p>143 genes were found to be significantly up-regulated in the heterozygous MEFs compared to their wild-type counterparts, while conversely, 9 genes were down-regulated. Numerous genes with increased transcript levels in heterozygous MEFs were identified to be involved in p53-dependent pathways. Furthermore, examination of the promoter regions of all up- and down-regulated genes revealed that the majority contained putative p53 responsive elements.</p> <p>An analysis of transcript levels in MEFs after exposure to either ionizing or ultraviolet radiation revealed a significant change between wild type and heterozygous MEFS for Plk4 transcript levels upon only UV exposure. Furthermore, changes in protein levels of several important cell check-point and apoptosis regulators were examined, including p53, Chk1, Chk2, Cdc25C and p21. In heterozygous MEFs, p53, p21 and Chk2 protein levels were at significantly higher levels. Furthermore, p53 activity was increased 5 fold in the <it>Plk4 </it>heterozygous MEFs.</p> <p>Conclusion</p> <p>Global transcript profiles and levels of key proteins involved in cellular proliferation and DNA damage pathways were examined in wild-type and <it>Plk4 </it>heterozygous MEFs. It was determined that Plk4 haploinsufficiency leads to changes in the levels of RNA accumulation for a number of key cellular genes as well as changes in protein levels for several important cell cycle/DNA damage proteins. We propose a model in which reduced Plk4 levels invoke an increase in p53 levels that leads to the aforementioned changes in global transcription profiles.</p
A Post-Amadori Inhibitor Pyridoxamine Also Inhibits Chemical Modification of Proteins by Scavenging Carbonyl Intermediates of Carbohydrate and Lipid Degradation
Reactive carbonyl compounds are formed during autoxidation of carbohydrates and peroxidation of lipids. These compounds are intermediates in the formation of advanced glycation end products (AGE) and advanced lipoxidation end products (ALE) in tissue proteins during aging and in chronic disease. We studied the reaction of carbonyl compounds glyoxal (GO) and glycolaldehyde (GLA) with pyridoxamine (PM), a potent post-Amadori inhibitor of AGE formation in vitro and of development of renal and retinal pathology in diabetic animals. PM reacted rapidly with GO and GLA in neutral, aqueous buffer, forming a Schiff base intermediate that cyclized to a hemiaminal adduct by intramolecular reaction with the phenolic hydroxyl group of PM. This bicyclic intermediate dimerized to form a five-ring compound with a central piperazine ring, which was characterized by electrospray ionization-liquid chromatography/mass spectrometry, NMR, and x-ray crystallography. PM also inhibited the modification of lysine residues and loss of enzymatic activity of RNase in the presence of GO and GLA and inhibited formation of the AGE/ALE N(epsilon)-(carboxymethyl)lysine during reaction of GO and GLA with bovine serum albumin. Our data suggest that the AGE/ALE inhibitory activity and the therapeutic effects of PM observed in diabetic animal models depend, at least in part, on its ability to trap reactive carbonyl intermediates in AGE/ALE formation, thereby inhibiting the chemical modification of tissue proteins
Adhesive Joining of Composite Laminates Using Epoxy Resins with Stoichiometric Offset
Polymer matrix composites are used in high performance structures because of their excellent specific strength, toughness and stiffness along the fiber. To realize the full performance advantages of composites, complex, built-up structures must be assembled with adhesive, but uncertainty in bond strength requires manufacturers to install bolts or other crack arrest features to ensure safety in critical applications. The inherent uncertainty in adhesive bonds stems from the material discontinuity at the composite-to-adhesive interfaces, which are susceptible to contamination. In contrast, composites made by co-curing, although limited in size and complexity, result in predictable structures that may be certifiable for commercial aviation with reduced dependence on redundant load paths.1 The pro-posed technology uses a stoichiometric offset of the hardener-to-epoxy ratio on the faying surfaces of laminates. Assembly of the components in a subsequent secondary-co-cure process results in a joint with no material discontinuities
Reliable Bonding of Composite Laminates Using Reflowable Epoxy Resins
Epoxy matrix composites assembled with adhesives maximize the performance of aerospace structures, but the possibility of forming weak bonds requires the installation of redundant fasteners, which add weight and manufacturing cost. Co-cured joints (e.g. unitized composite structures) are immune to weak bonds because the uncured resin undergoes diffusion and mixing through the joint. A means of co-curing complex structures may reduce the need for redundant fasteners in bondlines. To this end, NASA started the AERoBOND project to develop novel joining materials to enable a secondary-co-cure assembly process. Aerospace epoxy resin systems reformulated with offset stoichiometry prevented the resin from advancing beyond the gel point during a conventional autoclave cure cycle up to 180 C. The offset resins were applied to the joining surfaces of laminate preforms as prepreg. Two surfaces with complimentary offset resins were joined using conventional secondary bonding techniques. Preliminary efforts have indicated that the resulting joint has no discernable interface and appears as a conventional co-cured laminate under optical magnification. This report will discuss the initial work performed regarding formulation of the epoxy resin system using calorimetry, rheology, and mechanical testing
An Active Role for the Ribosome in Determining the Fate of Oxidized mRNA
Chemical damage to RNA affects its functional properties and thus may pose a significant hurdle to the translational apparatus; however, the effects of damaged mRNA on the speed and accuracy of the decoding process and their interplay with quality-control processes are not known. Here, we systematically explore the effects of oxidative damage on the decoding process using a well-defined bacterial in vitro translation system. We find that the oxidative lesion 8-oxoguanosine (8-oxoG) reduces the rate of peptide-bond formation by more than three orders of magnitude independent of its position within the codon. Interestingly, 8-oxoG had little effect on the fidelity of the selection process, suggesting that the modification stalls the translational machinery. Consistent with these findings, 8-oxoG mRNAs were observed to accumulate and associate with polyribosomes in yeast strains in which no-go decay is compromised. Our data provide compelling evidence that mRNA-surveillance mechanisms have evolved to cope with damaged mRNA
Implications of squirrelpox virus for successful red squirrel translocations within mainland UK
Remnant red squirrel populations in the UK mainland are threatened by squirrelpox viral disease and the reservoir of the squirrelpox virus, the invasive grey squirrel, is expanding its range. Until this threat can be effectively mitigated, there is a high risk from disease outbreaks, following proposed conservation translocation of red squirrels
1935: Abilene Christian College Bible Lectures - Full Text
Delivered in the auditorium of Abilene Christian College, Abilene, Texas, February 193
Gathering Galaxy Distances in Abundance with Roman Wide-Area Data
The extragalactic distance scale is fundamental to our understanding of
astrophysics and cosmology. In recent years, the surface brightness fluctuation
(SBF) method, applied in the near-IR, has proven especially powerful for
measuring galaxy distances, first with HST and now with a new JWST program to
calibrate the method directly from the tip of the red giant branch (TRGB). So
far, however, the distances from space have been gathered slowly, one or two at
a time. With the Roman Space Telescope, we have the opportunity to measure
uniformly high-quality SBF distances to thousands of galaxies out to hundreds
of Mpc. The impact of these data on cosmology and galaxy studies depends on the
specifics of the survey, including the filter selection, exposure depth, and
(especially) the sky coverage. While the baseline HLWAS survey in four filters
plus the grism would yield useful data, the impact would be limited by the
relatively small area. A more optimal approach would concentrate on the most
efficient passband (F146), adopt an exposure time sufficient to measure good
quality distances well out into the Hubble flow, and then maximize the sky
coverage within the total time constraints. Grism observations over the same
area can provide the needed information on redshifts and spectral energy
distributions for compact sources, while colors for larger objects can be
obtained from lower resolution surveys. The proposed plan will enable accurate
determination of the physical properties of thousands of nearby galaxies, an
independent measure of the Hubble constant with negligible statistical
error, and competitive constraints on .
The resulting data set will be a phenomenal resource for a wide range of
studies in astrophysics and cosmology.Comment: 5 pages; submitted to the call for Roman Core Community Survey white
paper
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