The Energetics of Ion-Pair and Hydrogen-Bonding Interactions in a Helical Peptide

A single pair of Glu and Lys residues has been placed at four different spacings, and in both orientations, in an otherwise neutral alanineglutamine peptide helix, and the contribution to helix stability of the different Glu-Lys interactions has been measured. The contribution from the interaction of each charged side chain with the helix macrodipole has also been determined. A side-chain interaction between Gln and Glu, when the spacing is (i, i+4), has been detected and quantified. The interactions have been divided into contributions from hydrogen bonds (independent of the concentration of NaC1) and from electrostatic interactions (present in 10 mM NaCl, absent in 2.5 M NaCl). The major results are as follows: (1) The (i, i+3) and (i, i+4) Glu-Lys interactions are helix-stabilizing and are similar in strength to each other, regardless of the orientation of the side chains. (2) Hydrogen bonds provide the major contribution to these side-chain interactions, as shown by the following facts. First, the major part of the interaction observed in 10 mM NaCl, pH 7, is still present in 2.5 M NaCl. Second, the interaction found at pH 2 is equally as strong as that found in 2.5 M NaCl at pH 7. (3) The (i, i+4) Gln-Glu side-chain hydrogen bond is as strong as the hydrogen-bond component of the Glu-Lys interaction at both pH 2 and pH 7. The Gln-Glu interaction differs from the Glu-Lys interaction in being specific both for the orientation and the spacing of the residues. (4) No significant hydrogen-bonding interaction was found for the (i, i+1) or (i, i+2) Glu-Lys spacings, either at pH 2 or at pH 7, in 2.5 M NaCl. At 10 mM NaCl and pH 7, these spacings show a helix-destabilizing electrostatic interaction which probably results from stabilization of the coil conformation

Auditory In-Vehicle Technologies to Support Older Drivers

OBJECTIVES Population aging, in combination with improved health care and more active lifestyles well into advanced age, have resulted in an increased number of older adults driving more miles than ever before. Unfortunately, these older drivers are over-represented in motor vehicle crashes and crash-related fatalities. Rather than the risk-tasking behaviors observed in young drivers, the collisions of older drivers frequently involve perceptual-cognitive errors. Advanced in-vehicle technologies have the potential to function as sensory-cognitive aids and may offset the negative impact of age-related changes in sensory and cognitive abilities. Collision Avoidance Systems (CASs) function as sensory aids to augment hazard detection capabilities, and therefore may be of particular benefit to older drivers. Navigation aids can offset the working memory requirements of wayfinding, and auditory guidance directions may reduce the visual demands of searching for street signs and reading maps. However, these advanced systems also have the potential to increase the information processing demands of the driving task or distract drivers, particularly if they are not designed in accordance with the sensory and perceptual capabilities of older adults. A series of experiments aimed at examining the impact of sensory-cognitive characteristics of auditory navigational aids on driver wayfinding, performance on a visual peripheral detection task, and neurophysiological, behavioral and subjective indices of driver mental workload and performance were conducted. METHODS Results of two investigations will be discussed. The first investigation examined the impact of amplitude level on working memory. Older adults frequently exhibit reduced complex working memory span. However, recent evidence indicates that increasing a sound’s amplitude increases its duration in echoic memory (Baldwin, in press). Based on these findings, we hypothesized that increasing the amplitude of verbal material would improve working memory efficiency. RESULTS In support of this hypothesis, a strong positive correlation between the amplitude level at which the verbal material was presented and complex working memory span as measured by a version of Daneman and Carpenter’s (1980) Listening span task was observed. This positive relationship OBJECTIVES Population aging, in combination with improved health care and more active lifestyles well into advanced age, have resulted in an increased number of older adults driving more miles than ever before. Unfortunately, these older drivers are over-represented in motor vehicle crashes and crash-related fatalities. Rather than the risk-tasking behaviors observed in young drivers, the collisions of older drivers frequently involve perceptual-cognitive errors. Advanced in-vehicle technologies have the potential to function as sensory-cognitive aids and may offset the negative impact of age-related changes in sensory and cognitive abilities. Collision Avoidance Systems (CASs) function as sensory aids to augment hazard detection capabilities, and therefore may be of particular benefit to older drivers. Navigation aids can offset the working memory requirements of wayfinding, and auditory guidance directions may reduce the visual demands of searching for street signs and reading maps. However, these advanced systems also have the potential to increase the information processing demands of the driving task or distract drivers, particularly if they are not designed in accordance with the sensory and perceptual capabilities of older adults. A series of experiments aimed at examining the impact of sensory-cognitive characteristics of auditory navigational aids on driver wayfinding, performance on a visual peripheral detection task, and neurophysiological, behavioral and subjective indices of driver mental workload and performance were conducted. METHODS Results of two investigations will be discussed. The first investigation examined the impact of amplitude level on working memory. Older adults frequently exhibit reduced complex working memory span. However, recent evidence indicates that increasing a sound’s amplitude increases its duration in echoic memory (Baldwin, in press). Based on these findings, we hypothesized that increasing the amplitude of verbal material would improve working memory efficiency. RESULTS In support of this hypothesis, a strong positive correlation between the amplitude level at which the verbal material was presented and complex working memory span as measured by a version of Daneman and Carpenter’s (1980) Listening span task was observed. This positive relationshi

Paleomagnetism and geochronology of the Ecstall pluton in the Coast Mountains of British Columbia: Evidence for local deformation rather than large-scale transport

Samples for geochronologic, geobarometric, and paleomagnetic analyses were collected across the northern portion of the Ecstall pluton southeast of Prince Rupert, British Columbia. Al-in-hornblende geobarometry indicates pressures from 740 ± 10 to 840 ± 30 MPa corresponding to crystallization depths of ∼25 to ∼30 km. U/Pb analyses of zircons from western, central, and eastern localities within the pluton yield crystallization ages of 91.5 ± 1.0 Ma, 90.8 ± 1.0 Ma, and 90.5 ± 1.0 Ma, respectively. Rock magnetic experiments, reflected light microscopy, and thermal demagnetization behavior suggest that natural remanent magnetism is carried by low-Ti titanohematite. Unblocking temperatures of the characteristic remanent magnetization (ChRM) are dominantly in the 560°C to 630°C range, with age of magnetization approximated by the 40Ar/39Ar hornblende ages of 84.2 ± 0.10 Ma on the western margin and 76.4 ± 0.6 Ma in the center of the pluton. Site-mean ChRM directions were isolated for paleomagnetic samples from 23 sites and are distributed along a small circle with subhorizontal axis at ∼340° azimuth. ChRM directions from the central portion of the pluton are concordant with the expected Cretaceous magnetic field direction, while ChRM directions from the western margin are discordant by \u3e70°. Folding of the Ecstall pluton, either during Late Cretaceous west directed thrust transport above the convex upward Prince Rupert Shear Zone or during younger deformation of the pluton and underlying shear zone, can account for the paleomagnetic data and is consistent with the geochronologic, geobarometric, and structural geologic observations

Perturbation Dynamics of the Rumen Microbiota in Response to Exogenous Butyrate

The capacity of the rumen microbiota to produce volatile fatty acids (VFAs) has important implications in animal well-being and production. We investigated temporal changes of the rumen microbiota in response to butyrate infusion using pyrosequencing of the 16S rRNA gene. Twenty one phyla were identified in the rumen microbiota of dairy cows. The rumen microbiota harbored 54.5±6.1 genera (mean ± SD) and 127.3±4.4 operational taxonomic units (OTUs), respectively. However, the core microbiome comprised of 26 genera and 82 OTUs. Butyrate infusion altered molar percentages of 3 major VFAs. Butyrate perturbation had a profound impact on the rumen microbial composition. A 72 h-infusion led to a significant change in the numbers of sequence reads derived from 4 phyla, including 2 most abundant phyla, Bacteroidetes and Firmicutes. As many as 19 genera and 43 OTUs were significantly impacted by butyrate infusion. Elevated butyrate levels in the rumen seemingly had a stimulating effect on butyrate-producing bacteria populations. The resilience of the rumen microbial ecosystem was evident as the abundance of the microorganisms returned to their pre-disturbed status after infusion withdrawal. Our findings provide insight into perturbation dynamics of the rumen microbial ecosystem and should guide efforts in formulating optimal uses of probiotic bacteria treating human diseases

Diversity patterns associated with varying dispersal capabilities as a function of spatial and local environmental variables in small wetlands in forested ecosystems

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. The diversity of species on a landscape is a function of the relative contribution of diversity at local sites and species turnover between sites. Diversity partitioning refers to the relative contributions of alpha (local) and beta (species turnover) diversity to gamma (regional/landscape) diversity and can be influenced by the relationship between dispersal capability as well as spatial and local environmental variables. Ecological theory predicts that variation in the distribution of organisms that are strong dispersers will be less influenced by spatial properties such as topography and connectivity of a region and more associated with the local environment. In contrast, the distribution of organisms with limited dispersal capabilities is often dictated by their limited dispersal capabilities. Small and ephemeral wetlands are centers of biodiversity in forested ecosystems. We sampled 41 small and ephemeral wetlands in forested ecosystems six times over a two-year period to determine if three different taxonomic groups differ in patterns of biodiversity on the landscape and/or demonstrate contrasting relationships with local environmental and spatial variables. We focused on aquatic macroinvertebrates (aerial active dispersers consisting predominantly of the class Insecta), amphibians (terrestrial active dispersers), and zooplankton (passive dispersers). We hypothesized that increasing active dispersal capabilities would lead to decreased beta diversity and more influence of local environmental variables on community structure with less influence of spatial variables. Our results revealed that amphibians had very high beta diversity and low alpha diversity when compared to the other two groups. Additionally, aquatic macroinvertebrate community variation was best explained by local environmental variables, whereas amphibian community variation was best explained by spatial variables. Zooplankton did not display any significant relationships to the spatial or local environmental variables that we measured. Our results suggest that amphibians may be particularly vulnerable to losses of wetland habitat in forested ecosystems as they have high beta diversity. Consequently, the loss of individual small wetlands potentially results in local extirpations of amphibian species in forested ecosystems

Kinetic Mechanism of a Partial Folding Reaction. 1. Properties of the Reaction and Effects of Denaturants†

La présente thèse de doctorat consiste en une enquête globale sur le développement de l’humanisme dans le contexte du retour de la cour pontificale en Italie, au moment d’une crise majeure, le Grand Schisme d’Occident. Notre travail se propose, avant toute chose, de nouer les fils de deux histoires généralement conçues comme distinctes et d’en éclairer les interactions. Il s’agit, d’une part, de l’émergence, au tournant du xve siècle, d’une génération d’intellectuels que l’on considère comme ..

Quantification of Transcriptome Responses of the Rumen Epithelium to Butyrate Infusion using RNA-seq Technology

Short-chain fatty acids (SCFAs), such as butyrate, produced by gut microorganisms, play a critical role in energy metabolism and physiology of ruminants as well as in human health. In this study, the temporal effect of elevated butyrate concentrations on the transcriptome of the rumen epithelium was quantified via serial biopsy sampling using RNA-seq technology. The mean number of genes transcribed in the rumen epithelial transcriptome was 17,323.63 ± 277.20 (±SD; N = 24) while the core transcriptome consisted of 15,025 genes. Collectively, 80 genes were identified as being significantly impacted by butyrate infusion across all time points sampled. Maximal transcriptional effect of butyrate on the rumen epithelium was observed at the 72-h infusion when the abundance of 58 genes was altered. The initial reaction of the rumen epithelium to elevated exogenous butyrate may represent a stress response as Gene Ontology (GO) terms identified were predominantly related to responses to bacteria and biotic stimuli. An algorithm for the reconstruction of accurate cellular networks (ARACNE) inferred regulatory gene networks with 113,738 direct interactions in the butyrate-epithelium interactome using a combined cutoff of an error tolerance (ɛ = 0.10) and a stringent P-value threshold of mutual information (5.0 × 10−11). Several regulatory networks were controlled by transcription factors, such as CREBBP and TTF2, which were regulated by butyrate. Our findings provide insight into the regulation of butyrate transport and metabolism in the rumen epithelium, which will guide our future efforts in exploiting potential beneficial effect of butyrate in animal well-being and human health

Impaired receptor-mediated endocytosis by the asialoglycoprotein receptor in ethanol-fed mice: implications for studying the role of this receptor in alcoholic apoptosis

During receptor-mediated endocytosis (RME), extracellular molecules are internalized after being recognized and bound to specific cell surface receptors. In previous studies of the asialoglycoprotein receptor (ASGPR) in rats, we showed that ethanol impairs RME at multiple ASGPR sites. Ethanol administration has been shown to increase apoptosis, and we demonstrated increased sensitization to apoptotic induction in hepatocytes from ethanol-fed rats. Although a physiological role for the ASGPR has not been identified, investigators have shown its involvement in the uptake/clearance of apoptotic cells in vitvo. This suggests a potential role for the ASGPR in the removal of apoptotic cells, and the recent availability of an ASGPR-deficient mouse strain provides an excellent opportunity to examine the role of the ASGPR during ethanol impairment. In this study, we examined ethanol-impaired RME in mice and began the characterization of ASGPR-deficient mice for use in ethanol studies. Similar to our findings with rats, ligand binding, internalization, and degradation were decreased 45-50% in hepatocytes from ethanol-fed wild-type mice. In ASGPR-deficient mice, these parameters did not vary among the chow-fed, pair-fed control, or ethanol groups and were negligible compared with those of wild-type mice. TUNEL analysis of liver sections showed an ethanol-induced increase in apoptotic bodies in all mouse strains with a significant difference in the receptor-deficient mice. Further, the livers of ASGPR-deficient mice had three times more apoptotic bodies, in all feeding groups, compared with wild-type mice. These results support the use of the ASGPR-deficient mouse model for studying ethanol-induced liver injury, specifically ethanol-induced apoptosis

Does the South Carolina Upstate have \u27Isolated Wetlands\u27 and how do they Function? A Prelimiary Analysisn

2010 S.C. Water Resources Conference - Science and Policy Challenges for a Sustainable Futur