The development of a model of Alpha helix formation for transmembrane peptides

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references (leaf 26).Researchers have studied the folding and binding properties of peptides in water for many years, but only recently has anyone attempted to explore those same tendencies in an environment similar to that of a transmembrane protein incorporated into the phospholipid bilayer of the cell. To this end, we have been working on the synthesis of a group of peptides with the general sequence +H3N-Ala2-Leu3-Ala7-Trp-Ala-X-Ala10-Lys6-COOH, where we will substitute all twenty naturally occurring amino acids into position X. We have successfully synthesized and purified the peptide in which the guest position X is filled by an isoleucine-due to the difficulty of the sequence involved, we have been unable to synthesize and purify eighteen of the remaining nineteen. Peptides, once synthesized, are characterized by MALDI mass spectrometry and HPLC and purified peptides are studied using circular dichroism (CD) spectroscopy to determine the a-helicity. Initial results suggest that the transmembrane environment will indeed alter the propensities of the various amino acid residues to form a-helices, though to what degree still remains to be seen. Once complete, this study should make it possible to determine a system for predicting a-helix formation in membrane proteins and determine the basic rules that guide such helix formation

LAT Perspectives in Detection of High Energy Cosmic Ray Electrons

The GLAST Large Area Telescope (LAT) science objectives and capabilities in the detection of high energy electrons in the energy range from 20 GeV to approx. 1 TeV are presented. LAT simulations are used to establish the event selections. It is found that maintaining the efficiency of electron detection at the level of 30% the residual hadron contamination does not exceed 2-3% of the electron flux. LAT should collect approx. ten million of electrons with the energy above 20 GeV for each year of observation. Precise spectral reconstruction with high statistics presents us with a unique opportunity to investigate several important problems such as studying galactic models of IC radiation, revealing the signatures of nearby sources such as high energy cutoff in the electron spectrum, testing the propagation model, and searching for KKDM particles decay through their contribution to the electron spectrum

Dark Matter in the Coming Decade: Complementary Paths to Discovery and Beyond

In this report we summarize the many dark matter searches currently being pursued through four complementary approaches: direct detection, indirect detection, collider experiments, and astrophysical probes. The essential features of broad classes of experiments are described, each with their own strengths and weaknesses. The complementarity of the different dark matter searches is discussed qualitatively and illustrated quantitatively in two simple theoretical frameworks. Our primary conclusion is that the diversity of possible dark matter candidates requires a balanced program drawing from all four approaches.Comment: Report prepared for the Community Summer Study (Snowmass) 2013, on behalf of Cosmic Frontier Working Groups 1-4 (CF1: WIMP Dark Matter Direct Detection, CF2: WIMP Dark Matter Indirect Detection, CF3: Non-WIMP Dark Matter, and CF4: Dark Matter Complementarity); published versio

Development of a Molecular Genetic Method for Characterizing Amphibian Diets

DEVELOPMENT OF A MOLECULAR GENETIC METHOD FOR CHARACTERIZING AMPHIBIAN DIETS.Alexander Funk* and Todd W. Pierson, Department of Ecology and Evolutionary Biology, University of Tennessee Knoxville, [email protected] Dietary studies can provide key insights into the ecology and behavior of animals. Methods common in dietary studies of amphibians (e.g., gastric lavage, fecal analysis, dissection) often fail to identify prey beyond the level of Order, are time intensive, and can be biased against soft-bodied prey. Here, we are developing a DNA metabarcoding assay to characterize amphibian diets from non-invasive fecal samples. In DNA metabarcoding, barcoding loci from mixed community samples (e.g., feces) are sequenced on a next-generation sequencing platform, and resulting reads are used to identify members of that community (e.g., diet composition). To validate this method, we will prepare COI amplicon libraries from 27 fecal samples collected from wild Blue Ridge two-lined salamander (Eurycea wilderae) during the breeding season. We will sequence these reads on an Illumina MiSeq and compare resulting reads against a reference library of sequences of known identity to characterize invertebrate diet composition. Some of our samples are derived from male E. wilderae with two alternative reproductive tactics-“searching” and “guarding”. Because the latter is more likely to be found in aquatic habitats in the breeding season, we expect to find a great representation of aquatic invertebrates in its diet. We hope that this method will prove to be more accurate and efficient than previous methods, providing a new, versatile tool with which amphibian diets can be characterized and compared

Dissecting the theories of lanthanide magnetic resonance

The NMR relaxation and chemical shift behaviour of isostructural series of macrocyclic lanthanide(III) complexes has been investigated. The 1H, 31P and 19F longitudinal relaxation rates of multiple series of lanthanide(III) complexes (Tb, Dy, Ho, Er, Tm, Yb) have been measured in solution at five magnetic field strengths in the range 4.7 to 16.5 Tesla. The electronic relaxation time, T1e, is a function of both the lanthanide(III) ion and the local ligand field. Analysis of the field-dependent nuclear relaxation rates, based on Solomon-Bloembergen Morgan theory, describing the paramagnetic enhancement of the nuclear relaxation rates, has allowed reliable estimates of the electronic relaxation times, T1e. It has been shown that in systems of high symmetry, the electronic relaxation times are directly proportional to the ligand field and that in some cases changing the ligand field can have a greater effect on the nuclear relaxation rates than lanthanide selection. The chemical shift data for the series of lanthanide(III) complexes were analysed. The pseudocontact shift of lanthanide(III) complexes is described by Bleaney’s theory of magnetic anisotropy. Most of the assumptions in this theory were shown to be questionable. In particular for systems in low symmetry significant deivations between the experimental chemical shifts and those predicted by theory were found. The low symmetry systems exhibit crystal field splittings of the same order of magnitude as the spin-orbit coupling. The possibility of a mixing of the electronic energy levels of the lanthanide(III) ion has to be considered. The effect of the coordination environment on the magnetic susceptibility was investigated using a variety of methods. Significant deviation (10 – 20%) from the theoretical values was observed in systems of low symmetry. These investigations show that paramagnetic relaxation enhancements and magnetic susceptibility are dependent on the ligand field. Applying this knowledge allows the design of more efficient paramagnetic probes, as needed in PARASHIFT magnetic resonance

Validity of Wrist-worn Physical Activity Monitors to Measure Heart Rate

Numerous physical activity monitors exist and are used to track and improve fitness levels. Due to the increasing popularity of these devices, newer products have been developed that measure heart rate (HR) at the wrist. Little is known about how accurate these devices are at measuring HR at the wrist and how they compare to each other. PURPOSE: To determine how accurately HR was measured by three different wrist-worn physical activity monitors. METHODS: Recreationally active men (n=9) and women (n=3) participated in this study. The average age and weight of participants was 22 ± 3 years and 73.9 ± 12 kg. TomTom Cardio (TT), Fitbit Surge (FB) and Microsoft Band (MB) physical activity monitors were used. The TT, FB, and MB were randomly assigned to the right or left wrist for each participant. The testing procedure included speeds of 2, 3, 4, 5, and 6 mph with each speed lasting three minutes. HR was measured by electrocardiography (ECG) using standard limb lead II and by the three different physical activity monitors. HR was recorded from each device every minute throughout the duration of the procedure. Pearson product moment correlations and bias between electrocardiography (ECG) and physical activity monitors with 95% limits of agreement (Bland-Altman analysis) were calculated. Repeated measures ANOVA [Speed x Device] were also calculated. Statistical significance was set at pRESULTS: At 2 mph and 3 mph, only TT HR was significantly correlated with ECG heart rate (r=0.693, p=0.012 and r=0.592, p=0.043). At 4 mph and 6 mph TT was significantly correlated with ECG (r=0.911, pCONCLUSION: With increasing speeds, physical activity monitors more accurately measure HR but individuals should be aware that these devices may overestimate HR during slower walking speeds

Effects of Chronic Sleep Restriction during Early Adolescence on the Adult Pattern of Connectivity of Mouse Secondary Motor Cortex

Cortical circuits mature in stages, from early synaptogenesis and synaptic pruning to late synaptic refinement, resulting in the adult anatomical connection matrix. Because the mature matrix is largely fixed, genetic or environmental factors interfering with its establishment can have irreversible effects. Sleep disruption is rarely considered among those factors, and previous studies have focused on very young animals and the acute effects of sleep deprivation on neuronal morphology and cortical plasticity. Adolescence is a sensitive time for brain remodeling, yet whether chronic sleep restriction (CSR) during adolescence has long-term effects on brain connectivity remains unclear. We used viral-mediated axonal labeling and serial two-photon tomography to measure brain-wide projections from secondary motor cortex (MOs), a high-order area with diffuse projections. For each MOs target, we calculated the projection fraction, a combined measure of passing fibers and axonal terminals normalized for the size of each target. We found no homogeneous differences in MOs projection fraction between mice subjected to 5 days of CSR during early adolescence (P25–P30, ≥50% decrease in daily sleep, n=14) and siblings that slept undisturbed (n=14). Machine learning algorithms, however, classified animals at significantly above chance levels, indicating that differences between the two groups exist, but are subtle and heterogeneous. Thus, sleep disruption in early adolescence may affect adult brain connectivity. However, because our method relies on a global measure of projection density and was not previously used to measure connectivity changes due to behavioral manipulations, definitive conclusions on the long-term structural effects of early CSR require additional experiments