Microfluidic Devices for Studying Biomolecular Interactions

Microfluidic devices for monitoring biomolecular interactions have been invented. These devices are basically highly miniaturized liquid-chromatography columns. They are intended to be prototypes of miniature analytical devices of the laboratory on a chip type that could be fabricated rapidly and inexpensively and that, because of their small sizes, would yield analytical results from very small amounts of expensive analytes (typically, proteins). Other advantages to be gained by this scaling down of liquid-chromatography columns may include increases in resolution and speed, decreases in the consumption of reagents, and the possibility of performing multiple simultaneous and highly integrated analyses by use of multiple devices of this type, each possibly containing multiple parallel analytical microchannels. The principle of operation is the same as that of a macroscopic liquid-chromatography column: The column is a channel packed with particles, upon which are immobilized molecules of the protein of interest (or one of the proteins of interest if there are more than one). Starting at a known time, a solution or suspension containing molecules of the protein or other substance of interest is pumped into the channel at its inlet. The liquid emerging from the outlet of the channel is monitored to detect the molecules of the dissolved or suspended substance(s). The time that it takes these molecules to flow from the inlet to the outlet is a measure of the degree of interaction between the immobilized and the dissolved or suspended molecules. Depending on the precise natures of the molecules, this measure can be used for diverse purposes: examples include screening for solution conditions that favor crystallization of proteins, screening for interactions between drugs and proteins, and determining the functions of biomolecules

Use of indigenous knowledge and traditional practices in fisheries management: a case of Chisi Island, Lake Chilwa, Zomba

This paper presents results of a study, which examined local ecological knowledge and traditional management practices in lake resources management on Chisi Island. A combination of household questionnaires, semi structured interviews with key informants and focus group discussions were used to collect the required data for the study. The paper also includes review of other scientific studies done in the area to validate the survey results. The study found that Chisi inhabitants have developed and maintained some local ecological knowledge and practices that can have significant implications in scientific studies and on the management of lake resources on the Island. The practices included restricted cutting of Typha, fishing and access in sacred sites and conservation of mabawe. These traditional practices encouraged regeneration and sustainable utilisation of fish. The knowledge systems have been conserved and passed on from generation to generation through religious beliefs, taboos and myths. Some indigenous knowledge systems have been eroded over the past years due to changes in social structures, immigration and advent of new religions, adoption of new resource harvesting techniques and changes in life styles. Although these knowledge systems were not specifically meant for conservation of natural resources, the study argues that to achieve sustainable designs or implementation of natural resource management projects, there is need to integrate relevant existing indigenous knowledge systems that promote conservation of resources.Keywords: sustainable utilisation and conservation

Tethered Particle Motion Reveals that LacI·DNA Loops Coexist with a Competitor-Resistant but Apparently Unlooped Conformation

AbstractThe lac repressor protein (LacI) efficiently represses transcription of the lac operon in Escherichia coli by binding to two distant operator sites on the bacterial DNA and causing the intervening DNA to form a loop. We employed single-molecule tethered particle motion to observe LacI-mediated loop formation and breakdown in DNA constructs that incorporate optimized operator binding sites and intrinsic curvature favorable to loop formation. Previous bulk competition assays indirectly measured the loop lifetimes in these optimized DNA constructs as being on the order of days; however, we measured these same lifetimes to be on the order of minutes for both looped and unlooped states. In a range of single-molecule DNA competition experiments, we found that the resistance of the LacI-DNA complex to competitive binding is a function of both the operator strength and the interoperator sequence. To explain these findings, we present what we believe to be a new kinetic model of loop formation and DNA competition. In this proposed new model, we hypothesize a new unlooped state in which the unbound DNA-binding domain of the LacI protein interacts nonspecifically with nonoperator DNA adjacent to the operator site at which the second LacI DNA-binding domain is bound

Imaging Active Infection in vivo Using D-Amino Acid Derived PET Radiotracers.

Occult bacterial infections represent a worldwide health problem. Differentiating active bacterial infection from sterile inflammation can be difficult using current imaging tools. Present clinically viable methodologies either detect morphologic changes (CT/ MR), recruitment of immune cells (111In-WBC SPECT), or enhanced glycolytic flux seen in inflammatory cells (18F-FDG PET). However, these strategies are often inadequate to detect bacterial infection and are not specific for living bacteria. Recent approaches have taken advantage of key metabolic differences between prokaryotic and eukaryotic organisms, allowing easier distinction between bacteria and their host. In this report, we exploited one key difference, bacterial cell wall biosynthesis, to detect living bacteria using a positron-labeled D-amino acid. After screening several 14C D-amino acids for their incorporation into E. coli in culture, we identified D-methionine as a probe with outstanding radiopharmaceutical potential. Based on an analogous procedure to that used for L-[methyl-11C]methionine ([11C] L-Met), we developed an enhanced asymmetric synthesis of D-[methyl-11C]methionine ([11C] D-Met), and showed that it can rapidly and selectively differentiate both E. coli and S. aureus infections from sterile inflammation in vivo. We believe that the ease of [11C] D-Met radiosynthesis, coupled with its rapid and specific in vivo bacterial accumulation, make it an attractive radiotracer for infection imaging in clinical practice

A Study of the Correlation between Endoscopic and Histological Diagnoses in Gastroduodenitis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72433/1/j.1572-0241.1987.tb01777.x.pd

Weak lensing observations of the "dark" cluster MG2016+112

We investigate the possible existence of a high-redshift (z=1) cluster of galaxies associated with the QSO lens system MG2016+112. From an ultra-deep R- and less deep V- and I-band Keck images and a K-band mosaic from UKIRT, we detect ten galaxies with colors consistent with the lensing galaxy within 225h^{-1} kpc of the z=1.01 lensing galaxy. This represents an overdensity of more than ten times the number density of galaxies with similar colors in the rest of the image. We also find a group of seven much fainter objects closely packed in a group only 27h^{-1} kpc north-west of the lensing galaxy. We perform a weak lensing analysis on faint galaxies in the R-band image and detect a mass peak of a size similar to the mass inferred from X-ray observations of the field, but located 64" northwest of the lensing galaxy. From the weak lensing data we rule out a similar sized mass peak centered on the lensing galaxy at the 2 sigma level.Comment: 9 pages, 10 figures, submitted to A&A version with figure 4 at higher resolution can be downloaded from http://www.mpa-garching.mpg.de/~clowe/mg2016aa.ps.g

High-complexity extracellular barcoding using a viral hemagglutinin

While single-cell sequencing technologies have revealed tissue heterogeneity, resolving mixed cellular libraries into cellular clones is essential for many pooled screens and clonal lineage tracing. Fluorescent proteins are limited in number, while DNA barcodes can only be read after cell lysis. To overcome these limitations, we used influenza virus hemagglutinins to engineer a genetically encoded cell-surface protein barcoding system. Using antibodies paired to hemagglutinins carrying combinations of escape mutations, we developed an exponential protein barcoding system which can label 128 clones using seven antibodies. This study provides a proof of principle for a strategy to create protein-level cell barcodes that can be used in vivo in mice to track clonal populations

Quantitative investigation of the short-range magnetic correlations in candidate quantum spin liquid NaYbO2_2

We present a neutron diffraction study of NaYbO$_2$, a candidate quantum spin liquid compound hosting a geometrically frustrated triangular lattice of magnetic Yb$^{3+}$ ions. We observe diffuse magnetic scattering that persists to at least 20 K, demonstrating the presence of short-range magnetic correlations in this system up to a relatively high energy scale. Using reverse Monte Carlo and magnetic pair distribution function analysis, we confirm the predominant antiferromagnetic nature of these correlations and show that the diffuse scattering data can be well described by noninteracting layers of XY spins on the triangular lattice. We rule out Ising spins and short-range-ordered stripe or 120$^{\circ}$ phases as candidate ground states of NaYbO$_2$. These results are consistent with a possible QSL ground state in NaYbO$_2$ and showcase the benefit of combined reciprocal- and real-space analysis of materials with short-range magnetic correlations

It's a dry heat: Quantifying effects of increasing atmospheric moisture demand on native Oklahoma trees

Anthropogenic climate change is predicted to alter precipitation frequency and intensity across Oklahoma in the coming decades, leading to an increase in the frequency, intensity, and duration of extreme events such as soil drought. Concurrently, temperature is predicted to continue rising, causing an ever-increasing atmospheric demand from plants. While the effect of soil droughts has been extensively studied in recent years, the impact of ever-increasing atmospheric droughts on trees is less characterized. Trees regulate photosynthesis though the interactive effects of availability of soil water (supply) and atmospheric demand for water (Vapor Pressure Deficit, VPD). Using recent innovations, and a novel experimental design, we set out to test gas exchange response for three native Oklahoma tree species to varying levels of VPD, with the hypothesis that drought adapted species would be less sensitive to increasing VPD. Two of the species, Quercus stellata and Quercus marilandica, often occur on unfavorable dry sites, while Cercis canadensis is found in riparian areas and wet forest interiors. We exposed six trees of each species to a range of VPDs, between 1kPa and 3kPa, at a constant temperature under well-watered conditions. We measured rates of carbon assimilation and stomatal conductance at five intervals across our VPD measurement range using a LI-COR LI-6800 infrared gas analyzer. Relative rates of carbon assimilation and stomatal conductance decreased as VPD increased across taxa. However, C. canadensis decreased carbon assimilation much quicker than the Quercus species as VPD increased in support of our hypothesis. Our results provide a preliminary understanding of photosynthetic response across a range of VPDs for deciduous forest trees in Oklahoma. Additionally, our methods provide a clear and repeatable way forward, as we aim to disentangle the effects of soil and atmospheric drought on photosynthetic rates in future experiments.Lew Wentz FoundationPlant Biology, Ecology and Evolutio

Reduction of Erosion Risk in Adult Patients with Implanted Ports

To reduce the percent of port erosion per year to at or below the number reported in the literature.https://digitalcommons.centracare.com/nursing_posters/1004/thumbnail.jp