Effect of Water Content on the Glass Transition Temperature of Calcium Maltobionate and its Application to the Characterization of Non-Arrhenius Viscosity Behavior

To understand the fundamental physical properties of calcium maltobionate (MBCa), its water sorption isotherm, glass transition temperature (T _g), and viscosity (η) were investigated and compared with those of maltobionic acid (MBH) and maltose. Although amorphous maltose crystalized at water activity (a _w) higher than 0.43, MBCa and MBH maintained an amorphous state over the whole a _w range. In addition, MBCa had a higher T _g and greater resistance to water plasticizing than MBH and maltose. These properties of MBCa likely originate from the strong interaction between MBCa and water induced by electrostatic interactions. Moreover, the effects of temperature and water content on η of an aqueous MBCa solution were evaluated, and its behavior was described using a semi-empirical approach based on a combination of T _g extrapolated by the Gordon-Taylor equation and a non-Arrhenius formula known as the Vogel–Fulcher–Tammann equation. This result will be useful for understating the effect of MBCa addition on the solution’s properties.     

Phylogeographic-based conservation implications for the New Zealand long-tailed bat, (<Emphasis Type="Italic">Chalinolobus tuberculatus</Emphasis>): identification of a single ESU and a candidate population for genetic rescue

The New Zealand long-tailed bat (Chalinolobus tuberculatus) is an endemic species threatened with extinction. Since the arrival of humans, massive deforestation has occurred and invasive mammalian predators were introduced. As a result, C. tuberculatus’ distribution shrank dramatically and became fragmented. To aid the management of the remaining populations, two Evolutionary Significant Units (ESUs) were designated: one on each of New Zealand’s main islands. We utilised mitochondrial sequence data (cytb, 703 bp) and 10 nuclear DNA microsatellite loci to reconstruct the demographic history of this species, to characterise the level of genetic diversity in remaining populations, and to assess the current connectivity between them. Our results indicate that the North Island, with the highest genetic diversity, served as a glacial refuge, with a loss of diversity following the path recolonization to the south of the South Island. However, our data are also consistent with continued, or at least very recent, genetic exchange between colonies across the species distribution. The only exception is the Hanging Rock colony on the east coast of the South Island, which appears to be isolated. Thus, there was no support for the previously designated ESUs. Signatures of past population declines were found in three colonies, the most extreme of which was found in Hanging Rock. Consequently, we recommend that it be genetically rescued via translocation from a donor population. In general, future management priorities should treat Chalinolobus tuberculatus as a single unit, focusing on maintaining connectivity between remaining populations, together with continued roost protection and pest control.     

Age and sex-dependent effects of landscape cover and trapping on the spatial genetic structure of the stone marten (<Emphasis Type="Italic">Martes foina</Emphasis>)

Maintenance of genetic variation is of critical importance for wild populations since low levels limit the species’ ability to respond to different threats (diseases, predators, environmental changes) in both the long and the short term. Human activities could impact the genetic variation of wild species in multiple ways, including via fragmentation and harvesting. We used an individual-based landscape genetics approach to describe the impact of landscape elements and trapping pressure on the spatial genetic structure of a large sample (n = 370) of the stone marten (Martes foina) in central-eastern France (Bresse). An analysis of isolation-by-resistance using a causal modeling approach showed an influence of landscape cover and/or trapping pressure on gene flow according to age and sex class. Overall, the connectivity in the study area is provided mainly by vegetation cover, while roads and open areas partially impede it. Unexpectedly for this “urban adapter” species, buildings could reduce gene flow. We also emphasized the sex-dependent effect of trapping on gene flow. Genetic differentiation in males was influenced by trapping pressure and landscape structure while only the latter influenced genetic differentiation in females. A stronger isolation by distance in males than in females suggested that at the scale of the study area, males are more exposed to trapping pressure, which reduces effective dispersal. Overall, the combination of both landscape and trapping costs might create an ‘ecological trap’ that could disrupt gene flow, leading to a north–south division in the study area.     

Genetic diversity and spatial genetic structure of African wild dogs (<Emphasis Type="Italic">Lycaon pictus</Emphasis>) in the Greater Limpopo transfrontier conservation area

The Greater Limpopo Transfrontier Conservation Area (GLTFCA) is one of the last refuges for the endangered African wild dog and hosts roughly one-tenth of the global population. Wild dogs in this area are currently threatened by human encroachment, habitat fragmentation and scarcity of suitable connecting habitat between protected areas. We derived genetic data from mitochondrial and nuclear markers to test the following hypotheses: (i) demographic declines in wild dogs have caused a loss of genetic variation, and (ii) Zimbabwean and South African populations in the GLTFCA have diverged due to the effects of isolation and genetic drift. Genetic patterns among five populations, taken with comparisons to known information, illustrate that allelic richness and heterozygosity have been lost over time, presumably due to effects of inbreeding and genetic drift. Genetic structuring has occurred due to low dispersal rates, which was most apparent between Kruger National Park and the Zimbabwean Lowveld. Immediate strategies to improve gene flow should focus on increasing the quality of habitat corridors between reserves in the GLTFCA and securing higher wild dog survival rates in unprotected areas, with human-mediated translocation only undertaken as a last resort.     

Antifungal Signature: Physicochemical and Structural In Silico Analysis of Some Antifungal Peptides

High throughput screening of antifungal peptide libraries have generated large number of information on peptide activities. However scientists are still struggling to explain the specific antifungal protein motifs resulting in their activities. So a thorough antifungal peptide optimization is required. To design and predict secondary structure of synthetic as well as natural antifungal peptide using in silico approaches, various parameters such as their sequences, physicochemical characterization, structures and functions should taken care to ensure a successful prediction. The primary interest of this study is to determine the properties that stabilize bonds of helices and coils of antifungal peptides along with their domains. Fifty different antifungal peptides have been analyzed in this study which were retrieved from uniprot and pdb databases and were characterized thoroughly using in silico tools. The present analysis showed that most of the antifungal peptides were hydrophobic in nature due to high content of nonpolar residues where as the functional domains were hydrophilic because of the presence of more polar residues. Many disulphide bonds were noticed in these peptides because of the presence of high cysteine residues which may be regarded as a positive factor for stability of linear helices and coils. Maximum number of random coils were observed in the domains of the studied peptides. The present study thus indicated that the peptidal domains of antifungal peptides contain structurally conserve signature though they are evolutionary diverse. Thus the present in silico models are able to guide the antifungal peptide design in a meaningful way.     

Intensive determination of storage condition effects on human plasma metabolomics

Introduction

Human plasma metabolomics offer powerful tools for understanding disease mechanisms and identifying clinical biomarkers for diagnosis, efficacy prediction and patient stratification. Although storage conditions can affect the reliability of data from metabolites, strict control of these conditions remains challenging, particularly when clinical samples are included from multiple centers. Therefore, it is necessary to consider stability profiles of each analyte.

Objectives

The purpose of this study was to extract unstable metabolites from vast metabolome data and identify factors that cause instability.

Method

Plasma samples were obtained from five healthy volunteers, were stored under ten different conditions of time and temperature and were quantified using leading-edge metabolomics. Instability was evaluated by comparing quantitation values under each storage condition with those obtained after ?80 °C storage.

Result

Stability profiling of the 992 metabolites showed time- and temperature-dependent increases in numbers of significantly changed metabolites. This large volume of data enabled comparisons of unstable metabolites with their related molecules and allowed identification of causative factors, including compound-specific enzymatic activity in plasma and chemical reactivity. Furthermore, these analyses indicated extreme instability of 1-docosahexaenoylglycerol, 1-arachidonoylglycerophosphate, cystine, cysteine and N⁶-methyladenosine.

Conclusion

A large volume of data regarding storage stability was obtained. These data are a contribution to the discovery of biomarker candidates without misselection based on unreliable values and to the establishment of suitable handling procedures for targeted biomarker quantification.

     

Effect of Cadmium Ion on alpha-Glucosidase: An Inhibition Kinetics and Molecular Dynamics Simulation Integration Study

α-Glucosidase is a critical metabolic enzyme that produces glucose molecules by catalyzing carbohydrates. The aim of this study is to elucidate biological toxicity of Cd²⁺ based on α-glucosidase activity and conformational changes. We studied Cd²⁺-mediated inactivation as well as conformational modulation of α-glucosidase by using kinetics coupled with simulation of molecular dynamics. The enzyme was significantly inactivated by Cd²⁺ in a reversibly binding behavior, and Cd²⁺ binding induced a non-competitive type of inhibition reaction (the K _i was calculated as 0.3863 ± 0.033 mM). Cd²⁺ also modulated regional denaturation of the active site pocket as well as overall partial tertiary structural change. In computational simulations using molecular dynamics, simulated introduction of Cd²⁺ induced in a depletion of secondary structure by docking Cd²⁺ near the saccharides degradation at the active site, suggesting that Cd²⁺ modulating enzyme denaturation. The present study elucidated that the binding of Cd²⁺ triggers conformational changes of α-glucosidase as well as inactivates catalytic function, and thus suggests an explanation of the deleterious effects of Cd²⁺ on α-glucosidase.     

Can Carnosine Prevent the Aging-Induced Changes of Blood Platelet and Brain Regional Monoamine Oxidase-A mRNA in Relation to its Activity?

It is well known that the monoamine oxidase (MAO) activity deregulates during aging along with anti-oxidant activity. Carnosine (β-Ala-l-His) is an endogenous dipeptide biomolecule, having both anti-oxidant and anti-glycating properties. The present study deals with the effect of carnosine on aging-induced changes in MAO-A mRNA expression of brain regions and blood platelets in relation to their MAO-A activity. Results showed that aging significantly and characteristically increased the brain regional MAO-A mRNA whereas, in blood platelets it was significantly reduced with an increase in blood platelet counts. Carnosine attenuated both aging-induced (i) increase in brain regional MAO-A mRNA expression and blood platelet count, (ii) decrease in blood platelet MAO-A mRNA expression and its (platelet MAO-A) activity without affecting the young rats’ brain regions and platelet. The present results thus suggest that carnosine attenuated and restored the aging-induced (a) increase of platelet count and (b) changes in brain regional and blood platelet MAO-A mRNA expression and (c) decrease in platelet MAO-A activity, towards their respective basal level that were observed in young rats.     

Oxytocin Sustained Release Using Natural Rubber Latex Membranes

The demand for biomaterials with properties that provide sustained release of substances with pharmacological interest is constant. One candidate for applications in this area is the Natural Rubber Latex (NRL) extracted from the rubber tree Hevea brasiliensis. Recent studies indicate the NRL as a matrix for sustained release, showing promising results for biomedical applications such as: can stimulate natural angiogenesis and is capable of adhering cells on its surface, promoting the replacement and regeneration of tissue. So, the NRL is an excellent candidate to propitiate the sustained release of peptides of pharmacological interest such as oxytocin, a hormonal peptide which has the function to promote uterine muscle contractions and reduce bleeding during childbirth, and stimulate the release of breast milk. Results demonstrated that 90 μg mL^?1 (45 %) of the incorporated peptide in Natural Rubber Latex Biomedical (NRLb) functionalized membranes was released at 10 h in phosphate-buffered saline (PBS) solution. Swelling kinetics assay showed that the NRLb membranes are able to absorb over a period of 16 h up to 1.08 grams of water per grams of membrane. Scanning electron microscopy showed that the peptide was adsorbed on the surface and within NRLb membrane. Fourier transform infrared and Derivative Thermogravimetric analysis indicated that oxytocin did not interacted chemically with the membrane. Furthermore, hemolysis of erythrocytes, quantified spectrophotometrically using materials (Oxytocin, NRLb, and NRLb + Oxytocin) showed no hemolytic effects up to 100 μg mL^?1 (compounds and mixtures), indicating no detectable disturbance of the red blood cell membranes. Based on these results it was possible to conclude that the NRLb has shown effectiveness as a model in the release of peptides with pharmacological interest.