Increase in takeover protection and firm knowledge accumulation strategy

Ministry of Education, Singapore under its Academic Research Funding Tier 1http://dx.doi.org/10.5465/aomafr.2012.0226 is AOM Proceedings version</p

Motorized Photomodulator:Making A Non-photoresponsive Supramolecular Gel Switchable by Light

Introducing photo-responsive molecules offers an attractive approach for remote and selective control and dynamic manipulation of material properties. However, it remains highly challenging how to use a minimal amount of photo-responsive units to optically modulate materials that are inherently inert to light irradiation. Here we show that the application of a light-driven rotary molecular motor as a "motorized photo-modulator" to endow a typical H-bond-based gel system with the ability to respond to light irradiation creating a reversible sol-gel transition. The key molecular design feature is the introduction of a minimal amount (1 mol%) of molecular motor into the supramolecular network as a photo-switchable non-covalent crosslinker. Advantage is taken of the subtle interplay of the large geometry change during photo-isomerization of the molecular motor guest and the dynamic nature of a supramolecular gel host system. As a result, a tiny amount of molecular motors is enough to switch the mechanical modulus of the entire supramolecular systems. This study proves the concept of designing photo-responsive materials with minimum use of non-covalent light-absorbing units.</p

Assessing the performance of a multi-nested ocean circulation model using satellite remote sensing and in situ observations

This study presents a multi-nested ocean circulation model developed recently for the central Scotian Shelf. The model consists of four submodels downscaling from the eastern Canadian Shelf to the central Scotian Shelf. The model is driven by tides, river discharges, and atmospheric forcing. The model results are validated against observations, including satellite remote sensing data from GHRSST and Aquarius and in situ measurements taken by tide gauges, a marine buoy, ADCPs and CTDs. The ocean circulation model is able to capture variations of sea level, hydrography and the Nova Scotia Current on timescales of days to seasons over the central Scotian Shelf. Model results are used in a process study to examine the effect of tidal mixing and wind-driven coastal upwelling in the formation of cold surface waters along the coast of Nova Scotia

Isolation and characterization of a novel podovirus which infects burkholderia pseudomallei

Burkholderia pseudomallei is a saprophytic soil bacterium and the etiological agent that causes melioidosis. It is naturally resistant to many antibiotics and therefore is difficult to treat. Bacteriophages may provide an alternative source of treatment. We have isolated and characterised the bacteriophage ΦBp-AMP1. The phage is a member of the Podoviridae family and has a genome size of ~ 45 Kb. Molecular data based on the gene which encodes for the phage tail tubular protein suggests that the phage is distinct from known phages but related to phages which infect B. thailandensis and Ralstonia spp. The phage ΦBp-AMP1 is the first B. pseudomallei podovirus to be isolated from the environment rather than being induced from a bacterial culture. It has a broad host range within B. pseudomallei and can infect all 11 strains that we tested it on but not related Burkholderia species. It is heat stable for 8 h at 50°C but not stable at 60°C. It may potentially be a useful tool to treat or diagnose B. pseudomallei infections as it can lyse several strains of clinical relevance

Diversity, Dynamics and Therapeutic Application of Clostridioides difficile Bacteriophages

Clostridioides difficile causes antibiotic-induced diarrhoea and pseudomembranous colitis in humans and animals. Current conventional treatment relies solely on antibiotics, but C. difficile infection (CDI) cases remain persistently high with concomitant increased recurrence often due to the emergence of antibiotic-resistant strains. Antibiotics used in treatment also induce gut microbial imbalance; therefore, novel therapeutics with improved target specificity are being investigated. Bacteriophages (phages) kill bacteria with precision, hence are alternative therapeutics for the targeted eradication of the pathogen. Here, we review current progress in C. difficile phage research. We discuss tested strategies of isolating C. difficile phages directly, and via enrichment methods from various sample types and through antibiotic induction to mediate prophage release. We also summarise phenotypic phage data that reveal their morphological, genetic diversity, and various ways they impact their host physiology and pathogenicity during infection and lysogeny. Furthermore, we describe the therapeutic development of phages through efficacy testing in different in vitro, ex vivo and in vivo infection models. We also discuss genetic modification of phages to prevent horizontal gene transfer and improve lysis efficacy and formulation to enhance stability and delivery of the phages. The goal of this review is to provide a more in-depth understanding of C. difficile phages and theoretical and practical knowledge on pre-clinical, therapeutic evaluation of the safety and effectiveness of phage therapy for CDI

Diverse Temperate Bacteriophage Carriage in Clostridium difficile 027 Strains

The hypervirulent Clostridium difficile ribotype 027 can be classified into subtypes, but it unknown if these differ in terms of severity of C. difficile infection (CDI). Genomic studies of C. difficile 027 strains have established that they are rich in mobile genetic elements including prophages. This study combined physiological studies, electron microscopy analysis and molecular biology to determine the potential role of temperate bacteriophages in disease and diversity of C. difficile 027.We induced prophages from 91 clinical C. difficile 027 isolates and used transmission electron microscopy and pulsed-field gel electrophoresis to characterise the bacteriophages present. We established a correlation between phage morphology and subtype. Morphologically distinct tailed bacteriophages belonging to Myoviridae and Siphoviridae were identified in 63 and three isolates, respectively. Dual phage carriage was observed in four isolates. In addition, there were inducible phage tail-like particles (PT-LPs) in all isolates. The capacity of two antibiotics mitomycin C and norfloxacin to induce prophages was compared and it was shown that they induced specific prophages from C. difficile isolates. A PCR assay targeting the capsid gene of the myoviruses was designed to examine molecular diversity of C. difficile myoviruses. Phylogenetic analysis of the capsid gene sequences from eight ribotypes showed that all sequences found in the ribotype 027 isolates were identical and distinct from other C. difficile ribotypes and other bacteria species.A diverse set of temperate bacteriophages are associated with C. difficile 027. The observed correlation between phage carriage and the subtypes suggests that temperate bacteriophages contribute to the diversity of C. difficile 027 and may play a role in severity of disease associated with this ribotype. The capsid gene can be used as a tool to identify C. difficile myoviruses present within bacterial genomes

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Upper Paleozoic coal measures and unconventional natural gas systems of the Ordos Basin, China

Upper Paleozoic coal measures in the Ordos Basin consist of dark mudstone and coal beds and are important source rocks for gas generation. Gas accumulations include coal-bed methane (CBM), tight gas and conventional gas in different structural areas. CBM accumulations are mainly distributed in the marginal area of the Ordos Basin, and are estimated at 3.5 × 1012 m3. Tight gas accumulations exist in the middle part of the Yishan Slope area, previously regarded as the basin-centered gas system and now considered as stratigraphic lithologic gas reservoirs. This paper reviews the characteristics of tight gas accumulations: poor physical properties (porosity < 8%, permeability < 0.85 × 10−3 μm2), abnormal pressure and the absence of well-defined gas water contacts. CBM is a self-generation and self-reservoir, while gas derived from coal measures migrates only for a short distance to accumulate in a tight reservoir and is termed near-generation and near-reservoir. Both CBM and tight gas systems require source rocks with a strong gas generation ability that extends together over wide area. However, the producing area of the two systems may be significantly different