Perspectives of surface plasmon resonance sensors for optimized biogas methanation

Biogas production is becoming significantly viable as an energy source for replacing fossil‐based fuels. The further development of the biogas production process could lead to significant improvements in its potential. Wastewater treatment currently accounts for 3% of the electrical energy load in developed countries, while it could be developed to provide a source of nitrogen and phosphorus, in addition to energy. The improvement of anaerobic digestion (AD) detection technologies is the cornerstone to reach higher methane productivities and develop fully automatized processes to decrease operational costs. New sensors are requested to automatically obtain a better interpretation of the complex and dynamical internal reactor environment. This will require detailed systematic detection in order to realize a near‐optimal production process. In this review, optical fiber‐based sensors will be discussed to assess their potential for use in AD. There is currently a disparity between the complexity of AD, and online detection. By improving the durability, sensitivity, and cost of dissolved H₂ (as well as H₂S, acetic acid, ammonia, and methane) sensor technology, further understanding of the AD process may allow the prevention of process failure. The emergence of surface plasmon resonance (SPR) sensing with optical fibers coupled with the H₂‐sensitive metal palladium, allows detection of dissolved hydrogen in liquid. By implementing these SPR sensors into AD, improvements to the biogas production process, even at small scales, may be achieved by guiding the process in the optimum direction, avoiding the collapse of the biological process. This review intends to assess the feasibility of online, cost‐effective, rapid, and efficient detection of dissolved H₂, as well as briefly assessing H₂S, acetic acid, ammonia, and methane in AD by SPR.     

Positive short-term effects of sheep grazing on the alpine avifauna

Grazing by large herbivores may negatively affect bird populations. This is of great conservation concern in areas with intensive sheep grazing. Sheep management varies substantially between regions, but no study has been performed in less intensively grazed systems. In a fully replicated, landscape scale experiment with three levels of sheep grazing, we tested whether the abundance and diversity of an assemblage of mountain birds were negatively affected by grazing or if grazing facilitated the bird assemblage. Density of birds was higher at high sheep density compared with low sheep density or no sheep by the fourth grazing season, while there was no clear effect on bird diversity. Thus, agricultural traditions and land use politics determining sheep density may change the density of avifauna in either positive or negative directions.     

An effective sample preparation approach for screening the anticancer compound piceatannol using HPLC coupled with UV and fluorescence detection

Piceatannol, compared with the renowned resveratrol, is a better anticancer agent and a superior agent with other biological activities. However, as there are only few plants reported to contain minute quantity of piceatannol, the scarcity of sources greatly impedes the piceatannol-related researches. To explore new sources of piceatannol, we established a sample preparation approach for screening the piceatannol in plants using HPLC-UV-fluorescence detection. When the HPLC is coupled with UV and fluorescence detectors, the decrease of signals in interferences and increase of signal in piceatannol in the fluorescence chromatogram mark clearly the position of the piceatannol peak; ultimately, it allows identification without standards. In this study, we systematically evaluated the factors affecting the extraction efficiency of piceatannol in sample preparation. Of the sample preparation strategies studied, direct solvent extraction and liquid nitrogen treatment followed by solvent extraction gave satisfactory recoveries for both piceatannol and resveratrol. These approaches avoided time-consuming lyophilization procedure. In addition, all procedures must be done in the dark to avoid negative impact of irradiation from fluorescence light on the recoveries of piceatannol and resveratrol. With the present method, we re-examined the plants previously claimed to contain only resveratrol for their piceatannol contents. The species examined included Polygonum cuspidatum, Arachis hypogaea, Vitis thunbergii, and Ampelopsis brevipedunculaata. The results showed, for the first time, all these plants contain piceatannol. The finding implies that the resveratrol-containing plants may also contain piceatannol. The results demonstrate the feasibility of these sample preparation approaches and may further the understanding for the distribution of piceatannol in plants.     

Comparison of isocitrate dehydrogenase from three hyperthermophiles reveals differences in thermostability, cofactor specificity, oligomeric state, and phylogenetic affiliation

With the aim of gaining insight into the molecular and phylogenetic relationships of isocitrate dehydrogenase (IDH) from hyperthermophiles, we carried out a comparative study of putative IDHs identified in the genomes of the eubacterium Thermotoga maritima and the archaea Aeropyrum pernix and Pyrococcus furiosus. An optimum for activity at 90 degrees C or above was found for each IDH. PfIDH and ApIDH were the most thermostable with a melting temperature of 103.7 and 109.9 degrees C, respectively, compared with 98.3 and 98.5 degrees C for TmIDH and AfIDH, respectively. Analytical ultracentrifugation revealed a tetrameric oligomeric state for TmIDH and a homodimeric state for ApIDH and PfIDH. TmIDH and ApIDH were NADP-dependent (K(m)((NADP)) of 55.2 and 44.4 microm, respectively) whereas PfIDH was NAD-dependent (K(m)((NAD)) of 68.3 microm). These data document that TmIDH represents a novel tetrameric NADP-dependent form of IDH and that PfIDH is a homodimeric NAD-dependent IDH not previously found among the archaea. The homodimeric NADP-IDH present in A. pernix is the most common form of IDH known so far. The evolutionary relationships of ApIDH, PfIDH, and TmIDH with all of the available amino acid sequences of di- and multimeric IDHs are described and discussed.     

Human glutathione transferase A1-1 demonstrates both half-of-the-sites and all-of-the-sites reactivity

A study of the kinetics of a heterodimeric variant of glutathione transferase (GST) A1-1 has led to the conclusion that, although the wild-type enzyme displays all-of-the-sites reactivity in nucleophilic aromatic substitution reactions, it demonstrates half-of-the-sites reactivity in addition reactions. The heterodimer, designed to be essentially catalytically inactive in one subunit due to a single point mutation (D101K), and the two parental homodimers were analyzed with seven different substrates, exemplifying three types of reactions catalyzed by glutathione transferases (nucleophilic aromatic substitution, addition, and double-bond isomerization reactions). Stopped-flow kinetic results suggested that the wild-type GST A1-1 behaved with half-of-the-sites reactivity in a nucleophilic aromatic substitution reaction, but steady-state kinetic analyses of the GST A1-D101K heterodimer revealed that this was presumably due to changes to the extinction coefficient of the enzyme-bound product. In contrast, steady-state kinetic analysis of the heterodimer with three different substrates of addition reactions provided evidence that the wild-type enzyme displayed half-of-the-sites reactivity in association with these reactions. The half-of-the-sites reactivity was shown not to be dependent on substrate size, the level of saturation of the enzyme with glutathione, or relative catalytic rate.     

UV-visible spectral identification of the solution-phase and solid-phase permanganate oxidation reactions of thymine acetic acid

Solution-phase and solid-phase permanganate oxidation reactions of thymine acetic acid were investigated by spectroscopy. The spectral data showed the formation of a stable organomanganese intermediate, which was responsible for the rise in the absorbance at 420 nm. This result enables unambiguous interpretation of the absorbance change at 420 nm, as the intermediate permanganate ions could be isolated on the solid supports.     

Pathogenesis of renal ischemia/reperfusion injury: lessons from knockout mice

Ischemia/reperfusion-induced acute renal failure is a common clinical problem associated with a high morbidity and mortality. Upon hypoxic injury, the depletion of ATP causes mitochondrial dysfunction, and accumulation of intracellular sodium, calcium and reactive oxygen species. Subsequently, multiple enzyme systems including proteases, nitric oxide synthases, phospholipases and endonuclease are activated and responsible for cytoskeleton disruption, membrane damage, and DNA degradation, and eventually cell death. Ischemia/reperfusion injury also activates complement, cytokines, and chemokines, which are cytotoxic themselves, but also attract leukocytes into the ischemic area to cause further damage. The vascular endothelial cell injury and dysfunction prolong ischemia and induce vascular congestion, edema, and further infiltration of inflammatory cells. Many players in renal ischemia/reperfusion injury and their mechanisms have been investigated using genetically manipulated mouse models. In this review, we focus on the information gathered from these studies. Deficiency of the Na/Ca exchanger, inducible nitric oxide synthase, Caspase-1, A3 adenosine receptor, C3, C5, C6, Factor B, or midkine protects the kidney against I/R injury. Conversely, deficiency of the interleukin-1 receptor, osteopontin, C4, or recombination activation gene-1 is not protective, while the absence of adrenomedullin or endothelin receptor B delays the recovery of ischemia/reperfusion injury. The knowledge obtained from these studies provides new direction for designing potential therapeutic agents for treating ischemia/reperfusion injury.     

The use of genetic markers to measure genomic response to selection in livestock

A method to measure genomic response to natural and artificial selection by means of genetic markers in livestock is proposed. Genomic response through several levels of selection was measured using sequential testing for distorted segregation of alleles among selected and nonselected sons, single-sperm typing, and a test with records for growth performance. Statistical power at a significance level of 0.05 was >0.5 for a marker linked to a QTL with recombination fractions 0, 0.10, and 0.20 for detecting genomic responses for gene effects of 0.6, 0.7, and 1.0 phenotypic standard deviations, respectively. Genomic response to artificial selection in six commercial bull sire families comprising 285 half-sib sons selected for growth performance was measured using 282 genetic markers evenly distributed over the cattle genome. A genome-wide test using selected sons was significant (P < 0.001), indicating that selection induces changes in the genetic makeup of commercial cattle populations. Markers located in chromosomes 6, 10, and 16 identified regions in those chromosomes that are changing due to artificial selection as revealed by the association of records of performance with alleles at specific markers. Either natural selection or genetic drift may cause the observed genomic response for markers in chromosomes 1, 7, and 17.     

Haemolymph parameters of Pacific white shrimp (Litopenaeus vannamei) infected with Taura syndrome virus

Pacific white shrimp (Litopenaeus vannamei) were injected with Taura syndrome virus (TSV) to assess shrimp immune responses and survival. TSV-infected shrimp suffered high mortality, but mock-infected and untreated shrimp experienced no mortality. Moribund shrimp were a pale, reddish colour and were lethargic and soft-shelled. Their haemolymph was clear red and coagulated poorly. In TSV-infected shrimp, the total haemocyte count (THC), hyalinocyte and granulocyte counts, and total plasma protein decreased significantly to 21%, 24%, 17% and 56% of untreated control values, respectively. Haemocyanin decreased to 67%, and clottable proteins to 80% of control values (P< 0.01). Copper and calcium ions, haemocytic transglutaminase (TGase) activity and plasma growth inhibitory activity against Vibrio harveyi also decreased significantly. Generation of intrahaemocytic superoxide anion, O(-2), in TSV-infected shrimp was significantly greater (P< 0.05) than in both control groups, no matter whether glucan stimulated or unstimulated. But the relative increase of intrahaemocytic O(-2) generation in TSV-infected shrimp response to glucan stimulation was lower in both controls. Plasma phenoloxidase (PO) activity increased significantly in TSV-infected shrimp. The plasma bacterial agglutinin titre against E. coli and V. harveyi, growth inhibition of E. coli and the concentration of magnesium ions in TSV-infected shrimp did not change significantly.In conclusion, ten of thirteen haemolymph parameters changed significantly during the host-TSV interaction. These parameters might be valuable references of shrimp health status.