Chlorocatechol detection based on a clc operon/reporter gene system

A sensitive and selective sensing system for chlorocatechols (3-chlorocatechol and 4-chlorocatechol) was developed based on Pseudomonas putida bacteria harboring the plasmid pSMM50R-B'. In this plasmid, the regulatory protein of the clc operon, ClcR, controls the expression of the reporter enzyme beta-galactosidase. When bacteria containing components of the clc operon are grown in the presence of chlorocatechols, ClcR activates the clcA promoter, which is located upstream from the beta-galactosidase gene. Thus, the concentration of chlorocatechols can be related to the production of beta-galactosidase in the bacteria. The concentration of beta-galactosidase expressed in the bacteria was determined by measuring the chemiluminescence signal emitted with the use of a 1,2-dioxetane substrate. ClcR has a high specificity for chlorocatechols and provides the sensing system with high selectivity. This was demonstrated by evaluating several structurally related organic compounds as potential interfering agents. Both 3-chlorocatechol and 4-chlorocatechol can be detected with this sensing system at concentrations as low as 8 x 10(-10) and 2 x 10(-9) M, respectively, using a 2-h induction period. In the case of 3-chlorocatechol, a highly selective sensing system was developed that can detect this species at concentrations as low as 6 x 10(-8) M after a 5-min induction period; the presence of 4-chlorocatechol at concentrations as high as 2 x 10(-4) M did not interfere with this system.     

VizCluster and its Application on Classifying Gene Expression Data

Visualization enables us to find structures, features, patterns, and relationships in a dataset by presenting the data in various graphical forms with possible interactions. A visualization can provide a qualitative overview of large and complex datasets, can summarize data, and can assist in identifying regions of interest and appropriate parameters focused on quantitative analysis. Recently, DNA microarray technology provides a broad snapshot of the state of the cell, by measuring the expression levels of thousands of genes simultaneously. Such information can thus be used to analyze different samples by gene expression profiles. It has already had a significant impact on the field of bioinformatics, requiring innovative techniques to efficiently and effectively extract, analyze, and visualize these fast growing data.In this paper, we present a dynamic interactive visualization environment, VizCluster, and its application on classifyinggene expression data. VizCluster takes advantage of graphical visualization methods to reveal underlining data patterns. It combines the merits of both high dimensional projection scatter-plot and parallel coordinate plot. In its core lies a nonlinear projection which maps the n-dimensional vectors onto two-dimensional points. To preserve the information at different scales and yet reduce the typical problem of parallel coordinate plots being messy caused by overlapping lines, a zip zooming viewing method is proposed. Integrated with other features, VizCluster is developed to give a simple, fast, intuitive, and yet powerful view of the data set. Its primary applications are on the classification of samples and evaluation of gene clusters for microarray datasets. Three gene expression datasets are used to illustrate the approach. We demonstrate that VizCluster approach is promising to be used for analyzing and visualizing microarray data sets and further development is worthwhile.     

Effects of succinate on ground beef color and premature browning

The objective of this experiment was to determine the effects of succinate on raw and cooked ground beef color. Chubs (n=10) were divided in half and assigned to either succinate (final w/w concentration of 2.5%) or distilled water. Patties (n=14 per chub half) were assigned to initial day 0 color and each of 6 treatment combinations, created by crossing 3 packaging types (vacuum, high-oxygen/80% O(2), and PVC) with 2 storage times (days 1 and 3). After storage, patties were cooked to either 66 °C or 71 °C. Succinate increased (P<0.05) ground beef pH and metmyoglobin reducing activity but had no effect (P>0.05) on raw a* and chroma values. Moreover, succinate decreased (P<0.05) raw L* values, lipid oxidation, and premature browning for patties packaged in PVC and high-oxygen. Succinate may increase cooked patty redness via its influence on meat pH.     

Development of fish gelatin edible films using extrusion and compression molding

Fish gelatin was plasticized with 20% and 25% glycerol (w/w of gelatin) and used to develop edible films by twin-screw extrusion at 110 and 120 °C followed by compression molding at 80 °C. Tensile and moisture barrier properties and glass transition temperature were then measured and compared with solution-cast films. The films extruded at 110 °C and with 25% glycerol had the highest percent elongation at break of 293 ± 27%. The water vapor permeability values of extruded films (the highest value being 2.9 ± 0.2 g mm h⁻¹ cm⁻² Pa⁻¹) were higher than those of solution-cast films while the glass transition temperatures (T_g) of the extruded films were generally lower than those of solution-cast films. Films with 25% glycerol that were extruded at 110 °C had the lowest T_g (2.10 ± 0.31 °C). This investigation showed that extrusion processing followed by compression molding is a feasible method to produce fish gelatin films for commercial applications in a wide range of food products.     

Effects of lactate on ground lamb colour stability and mitochondria-mediated metmyoglobin reduction

Previous research suggests that lactate’s colour stabilizing effect in beef is through NADH production and antioxidant activity. However, no research has assessed lactate’s role in lamb colour. Hence, our objectives were to evaluate the effects of lactate on lamb surface discolouration, oxygen consumption, and metmyoglobin reduction. In experiment 1, lactate (final meat concentration = 2.5% w/w) was added to ground lamb (n = 20 carcasses) and patties were stored for 3 days at 1 °C in PVC packaging. Surface colour (CIE L∗ and a∗) and metmyoglobin reducing activity of ground lamb patties were measured. Addition of lactate improved colour stability and metmyoglobin reducing activity (p < 0.05). In experiment 2, mitochondria were isolated from lamb longissimus muscle (n = 3). Addition of lactate–LDH–NAD to mitochondria resulted in significant oxygen consumption and metmyoglobin reduction compared with mitochondrial controls without lactate (p < 0.05). Lactate can improve the colour stability of lamb, possibly by increasing metmyoglobin reducing activity.     

Production of electricity during wastewater treatment using a single chamber microbial fuel cell

Microbial fuel cells (MFCs) have been used to produce electricity from different compounds, including acetate, lactate, and glucose. We demonstrate here that it is also possible to produce electricity in a MFC from domestic wastewater, while atthe same time accomplishing biological wastewater treatment (removal of chemical oxygen demand; COD). Tests were conducted using a single chamber microbial fuel cell (SCMFC) containing eight graphite electrodes (anodes) and a single air cathode. The system was operated under continuous flow conditions with primary clarifier effluent obtained from a local wastewater treatment plant. The prototype SCMFC reactor generated electrical power (maximum of 26 mW m(-2)) while removing up to 80% of the COD of the wastewater. Power output was proportional to the hydraulic retention time over a range of 3-33 h and to the influent wastewater strength over a range of 50-220 mg/L of COD. Current generation was controlled primarily by the efficiency of the cathode. Optimal cathode performance was obtained by allowing passive air flow rather than forced air flow (4.5-5.5 L/min). The Coulombic efficiency of the system, based on COD removal and current generation, was < 12% indicating a substantial fraction of the organic matter was lost without current generation. Bioreactors based on power generation in MFCs may represent a completely new approach to wastewater treatment. If power generation in these systems can be increased, MFC technology may provide a new method to offset wastewater treatment plant operating costs, making advanced wastewater treatment more affordable for both developing and industrialized nations.     

Comparison of quality and shelf life of buffalo meat patties stored at refrigeration temperature

Scientific investigation on the quality changes of processed meat products will boost and sustain the meat production and utilization in buffalo abundant countries. A programme was undertaken to compare the quality of buffalo meat patties made from intensively reared young male, semi extensively reared spent male and female groups and stored at refrigeration temperature (4 ± 1 °C). Buffalo meat patties were evaluated for shelf life attributes by analysing the changes in physicochemical, microbiological and sensory attributes. The overall acceptability of patties was better in spent buffalo group than young male group. Increasing storage time resulted in significantly higher pH, TBARS, total aerobic mesophils, coliforms, Staphylococcus aureus and psychrophilic counts but decreased appearance, flavour, juiciness, tenderness, connective tissue residue and overall acceptability scores of buffalo meat patties. The patties were well acceptable within 20 days in young male group and 25 days in spent buffalo group respectively during refrigerator storage.     

Photon-assisted oxidation and oxide thin film synthesis: A review

The article reviews an oxide materials synthesis approach utilizing photons. Photon-assisted oxide processing is an interesting and unique approach to synthesize ultra-thin oxides at relatively low temperatures. Photon-assisted oxidation can be implemented both during oxide synthesis as well as a post-deposition annealing step. The mechanisms governing photon-assisted oxygen incorporation into growing oxide films, namely, electric field and chemical effects are discussed. Experimental observations on representative oxide structures in the fluorite, rutile and perovskite family are highlighted. It is shown that the technique enables near-room temperature modification of structure and chemistry of oxide surfaces, interfaces with atomic-level control. Oxygen non-stoichiometry can be controllably tuned using this approach in a self-limiting manner. Potential relevance of the processing approach in the context of applications in emerging electronics and energy technologies are pointed out.