Highly Stable Plasmonic Nanostructures on a Nickel-Sputtered Glass and Polymeric Optical Fiber Sensors

Plasmonics - This study shows development of highly sensitive and stable localized surface plasmon resonance (LSPR)-active U-bent glass and polymeric optical fiber (GOF and POF) sensor probes by a...     

Explaining geographical variation in the isotope composition of mouse lemurs (Microcebus)

Aim We sought to quantify geographical variation in the stable isotope values of mouse lemurs (Microcebus) and to determine whether this variation reflects trophic differences among populations or baseline isotopic differences among habitats. If the latter pattern is demonstrated, then Microcebus can become a proxy for tracking baseline habitat isotopic variability. Establishing such a baseline is crucial for identifying niche partitioning in modern and ancient communities. Location We studied five species of Microcebus from eight distinct habitats across Madagascar. Methods We compared isotopic variation in C₃ plants and Microcebus fur within and among localities. We predicted that carbon and nitrogen isotope values of Microcebus should: (1) vary as a function of abiotic variables such as rainfall and temperature, and (2) covary with isotopic values in plants. We checked for trophic differences among Microcebus populations by comparing the average difference between mouse lemur and plant isotope values for each locality. We then used multiple regression models to explain spatial isotope variation in mouse lemurs, testing a suite of explanatory abiotic variables. Results We found substantial isotopic variation geographically. Ranges for mean isotope values were similar for both Microcebus and plants across localities (carbon 3.5–4.0‰; nitrogen 10.5–11.0‰). Mean mouse lemur and plant isotope values were lowest in cool, moist localities and highest in hot, dry localities. Rainfall explained 58% of the variation in Microcebus carbon isotope values, and mean plant nitrogen isotope values explained 99.7% of the variation in Microcebus nitrogen isotope values. Average differences between mouse lemur and plant isotope values (carbon 5.0‰; nitrogen 5.9‰) were similar across localities. Main conclusions Isotopic data suggest that trophic differences among Microcebus populations were small. Carbon isotope values in mouse lemurs were negatively correlated with rainfall. Nitrogen isotope values in Microcebus and plants covaried. Such findings suggest that nitrogen isotope values for Microcebus are a particularly good proxy for tracking baseline isotopic differences among habitats. Our results will facilitate future comparative research on modern mouse lemur communities, and ecological interpretations of extinct Holocene communities.     

Improving consensus structure by eliminating averaging artifacts

Background  

Common structural biology methods (i.e., NMR and molecular dynamics) often produce ensembles of molecular structures. Consequently, averaging of 3D coordinates of molecular structures (proteins and RNA) is a frequent approach to obtain a consensus structure that is representative of the ensemble. However, when the structures are averaged, artifacts can result in unrealistic local geometries, including unphysical bond lengths and angles.     

A microfluidic competitive immuno-aggregation assay for high sensitivity cell secretome detection

We report a high-sensitivity cell secretome detection method using competitive immuno-aggregation and a micro-Coulter counter. A target cell secretome protein competes with anti-biotin-coated microparticles (MPs) to bind with a biotinylated antibody (Ab), causing decreased aggregation of the functionalized MPs and formation of a mixture of MPs and aggregates. In comparison, without the target cell secretome protein, more microparticles are functionalized, and more aggregates are formed. Thus, a decrease in the average volume of functionalized microparticles/aggregates indicates an increase in cell secretome concentration. This volume change is measured by the micro-Coulter counter, which is used to quantitatively estimate the cell secretome concentration. Vascular endothelial growth factor (VEGF), one of the key cell secretome proteins that regulate angiogenesis and vascular permeabilization, was used as the target protein to demonstrate the sensing principle. A standard calibration curve was generated by testing samples with various VEGF concentrations. A detection range from 0.01 ng/mL to 100.00 ng/mL was achieved. We further demonstrated the quantification of VEGF concentration in exogenous samples collected from the secretome of human mesenchymal stem cells (hMSCs) at different incubation times. The results from the assay agree well with the results of a parallel enzyme-linked immunoabsorbent assay (ELISA) test, indicating the specificity and reliability of the competitive immuno-aggregation assay. With its simple structure and easy sample preparation, this assay not only enables high sensitivity detection of VEGF but also can be readily extended to other types of cell secretome analysis as long as the specific Ab is known.     

Dimensions of global population projections: what do we know about future population trends and structures?

The total size of the world population is likely to increase from its current 7 billion to 8–10 billion by 2050. This uncertainty is because of unknown future fertility and mortality trends in different parts of the world. But the young age structure of the population and the fact that in much of Africa and Western Asia, fertility is still very high makes an increase by at least one more billion almost certain. Virtually, all the increase will happen in the developing world. For the second half of the century, population stabilization and the onset of a decline are likely. In addition to the future size of the population, its distribution by age, sex, level of educational attainment and place of residence are of specific importance for studying future food security. The paper provides a detailed discussion of different relevant dimensions in population projections and an evaluation of the methods and assumptions used in current global population projections and in particular those produced by the United Nations and by IIASA.     

Circadian regulation of visually evoked potentials in the domestic pigeon, Columba livia

The avian circadian and visual systems are integrally related and together influence many aspects of birds' behavior and physiology. Certainly, light cycles and their visual perception are the major zeitgebers for circadian rhythms, but do circadian rhythms affect vision? To assess whether visual function is regulated on a circadian basis, flash-evoked electroretinograms (ERGs) and vision-evoked potentials (VEPs) from the optic tectum (TeO) were recorded simultaneously in domestic pigeons at different circadian phases in a light-dark regime (LD) and in constant darkness (DD), while feeding activity was measured to determine circadian phase. In both LD and DD, the amplitudes of ERG b-waves were higher during the day than at night and latencies of a- and b-waves were longer at night. The median effective intensity for ERG a-wave was marginally higher during the day than during the night, indicating greater sensitivity at night, but this rhythm did not persist in DD. The amplitudes of TeO VEPs were also greater during the day, and latencies were greater at night in LD and DD. Together, the data indicate that a circadian clock regulates pigeon visual function at several integrative levels.     

Generation of human antibody fragments against <Emphasis Type="Italic">Streptococcus mutans</Emphasis>using a phage display chain shuffling approach

Background  

Common oral diseases and dental caries can be prevented effectively by passive immunization. In humans, passive immunotherapy may require the use of humanized or human antibodies to prevent adverse immune responses against murine epitopes. Therefore we generated human single chain and diabody antibody derivatives based on the binding characteristics of the murine monoclonal antibody Guy's 13. The murine form of this antibody has been used successfully to prevent Streptococcus mutans colonization and the development of dental caries in non-human primates, and to prevent bacterial colonization in human clinical trials.