19,961 research outputs found
Organic poultry production and forage digestibility
The current experiments were conducted to evaluate organic poultry production and the digestibility of organic feeds and pasture forages. A performance study was conducted to determine the effect of exogenous non-starch polysaccharide (NSP) enzyme supplementation on the performance and carcass characteristics of organically-reared broiler chickens. The addition of an exogenous NSP enzyme cocktail improved the performance and carcass characteristics of organically-reared broilers given access to pasture only in spring months. Pasture forages may contribute digestible nutrients to poultry; however, this contribution has not been evaluated in past research. A digestibility study was conducted to determine the nitrogen-corrected apparent metabolizable energy (AMEn) and nitrogen-corrected true metabolizable energy (TME n) of organic broiler diets and pasture forages. Additionally, the true amino acid digestibility (TAAD) of pasture forages was evaluated using poultry as the model. Poultry given access to pasture can meet a portion of their nutrient requirements through pasture access
Self-Selected vs. Assigned Writing Topics: The Effects Topics Have on First Graders\u27 Writing Performance
When asked about early writing experiences in school, many adults have memories of writing papers on topics such as “What I Want to Learn in School This Year” or “My Favorite Trip.” The teacher probably thought that if the topic was of interest to her students, they would become motivated to write. In essence, the purpose for writing most often comes from the teacher, and not the students. Rarely are students allowed to choose their own topics for writing assignments. The focus of writing instruction is usually, therefore, is teacher-centered rather than child-centered. It has historically been the child\u27s task to ascertain just what the teacher wants in a writing piece
Topography Study of FIXa: Generation of a Lipid Anchored Molecular Ruler with Attached Inhibitor
Blood coagulation, an important hemostatic property, is directed through activation of proteolytic enzymes known as serine proteases to generate a fibrin plug. Using multiple proteases allows for localized and precise regulation of blood coagulation within the circulatory system. Factor IX, a serine protease, is a key activator in the coagulation cascade by activating Factor X. For activation of FX to occur, FIXa must be in proper conformation on the platelet surface with cofactor FVIIIa to increase enzymatic abilities of FIXa a billion-fold. Current research looks at structure and function of FIXa yet neglects structural plasticity on the membrane, with function of FIX clearly being related to conformation on the platelet. The role of this investigation was to study the optimal reactive topography of FIXa by generating AMRI, Adjustable height Molecular Ruler with attached Inhibitor. AMRI composed of three primary regions contains an Anchor region, Linker region, and Inhibitor. AMRI was generated using the protein anchoring sequence LAGC to fixate to a lipid surface. A height adjustable linker area was then required between the anchor and inhibitor regions of AMRI to ensure proper vertical height of inhibitor. The linker sequence EAAAK forms a rigid structure with a vertical height of 7.5A above the membrane surface, thus we repeated this sequence to achieve a specific desired height. Completing the protein’s linker region is a flexible linker at end of the rigid set. That flexible linker ensures the inhibitor will fit in FIXa active site. Finishing the AMRI complex is a PN2-KPI inhibitor, which has been demonstrated to fit and inhibit the catalytic site of FIXa. Therefore, AMRI should allow for determination of optimal reactive height of the FIXa active site without affecting structural conformation. Through the generation of AMRI, a greater insight into blood coagulation will be gained, along with potential for site specific anticoagulant clinical applications
Repatriation from expedition ship in South America
This is my first hand account, being on board as part of the expedition team — in the role of a field guide / geology lecturer / zodiac driver / general naturalist — during the entire COVID-19 crisis as it unfolded on the ship.https://dc.ewu.edu/covid/1018/thumbnail.jp
Impactite and pseudotachylite from Roter Kamm Crater, Namibia
Pseudotachylite is known to occur in a variety of geologic settings including thrust belts (e.g., the Alps and the Himalayas) and impact craters such as Roter Kamm, Namibia. Controversy exists, however, as to whether pseudotachylite can be produced by shock brecciation as well as by tectonic frictional melting. Also open to debate is the question of whether pseudotachylites form by frictional fusion or by cataclasis. It was speculated that the pseudotachylite at Roter Kamm was formed by extensional settling and adjustment of basement blocks during 'late modification stage' of impact. The occurrence of pseudotachylite in association with rocks resembling quenched glass bombs and melt breccias in a relatively young crater of known impact origin offers a rare opportunity to compare features of these materials. Petrographic, x-ray diffraction, and electron microprobe analyses of the impactites and pseudotachylites are being employed to determine the modes of deformation and to assess the role of frictional melting and comminution of adjacent target rocks
Serotonin Modulates Oscillations of the Membrane Potential in Isolated Spinal Neurons from Lampreys
Studies were performed on spinal neurons from lampreys isolated by an enzymatic/mechanical method using pronase. The effects of 100 µM serotonin (5-HT) on membrane potential oscillations induced by a variety of excitatory amino acids were studied. 5-HT was found to depolarize branched cells (presumptive motoneurons and interneurons) by 2–6 mV without inducing membrane potential oscillations. However, when oscillations were already present because of an excitatory amino acid, 5-HT changed the parameters of these oscillations, increasing the amplitudes of all types of oscillations, increasing the frequency of irregular oscillations, and increasing the duration of the depolarization plateaus accompanied by action potentials. Serotonin modulation of the effects of excitatory amino acids and the electrical activity of cells in the neural locomotor network facilitates motor activity and leads to increases in the contraction of truncal muscles and more intense movements by the animal. The possible mechanisms of receptor coactivation are discussed, along with increases in action potential frequency and changes in the parameters of the locomotor rhythm
The Effects of Serotonin on Functionally Diverse Isolated Lamprey Spinal Cord Neurons
The experiments reported here showed that application of serotonin (5-hydroxytryptamine, 5-HT) (100 µ M) did not induce any significant current through the membranes of any of the spinal neurons studied (n = 62). At the same time, the membranes of most motoneurons and interneurons (15 of 18) underwent slight depolarization (2–6 mV) in the presence of 5-HT, which was not accompanied by any change in the input resistance of the cells. Depolarization to 10–20 mV occurred in some cells (3 of 18) of these functional groups, this being accompanied by 20–60% decreases in input resistance. The same concentration of 5-HT induced transient low-amplitude depolarization of most sensory spinal neurons (dorsal sensory cells), this changing smoothly to long-term hyperpolarization by 2–7 mV. The input resistance of the cell membranes in these cases showed no significant change (n = 8). Data were obtained which provided a better understanding of the mechanism by which 5-HT modulates the activity of spinal neurons. Thus, 5-HT facilitates chemoreceptive currents induced by application of NMDA to motoneurons and interneurons, while the NMDA responses of dorsal sensory cells were decreased by 5-HT. 5-HT affected the post-spike afterresponses of neurons. 5-HT significantly decreased the amplitude of afterhyperpolarization arising at the end of the descending phase of action potentials in motoneurons and interneurons and increased the amplitude of afterdepolarization in these types of cells. In sensory spinal neurons, 5-HT had no great effect on post-spike afterresponses. The results obtained here support the suggestion that 5-HT significantly modulates the activity of spinal neurons of different functional types. 5-HT facilitates excitation induced by subthreshold depolarization in motoneurons and some interneurons, facilitating the generation of rhythmic discharges by decreasing afterhyperpolarization. In sensory cells, 5-HT enhances inhibition due to hyperpolarization, suppressing NMDA currents. The differences in the effects of 5-HT on functionally diverse neurons are presumed to be associated with the combination of different types of 5-HT receptors on the membranes of these types of spinal neurons
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