Search

Summary: The DNA-binding protein of starved cells (Dps) has two distinct cellular functions in Escherichia coli. The spherical Dps dodecamer can store iron and, predominantly in the stationary growth phase, high amounts of Dps protein protect the genome by binding non-specifically to DNA. In this study we investigated the role of Dps in copper homeostasis in growing cells of E. coli. Under reductive aerobic growth conditions that favor a redox shift from Cu(II) to Cu(I) or under anaerobiosis, cells deleted in dps were sensitive to low copper ion concentrations. Deletion of the DNA-binding N-terminus of Dps did not abrogate protection against copper toxicity indicating protection against copper stress is not directly related to DNA binding of Dps. The Dps protein is not a copper-storage protein in vitro or in vivo. In contrast, cells lacking Dps exhibited increased cellular copper concentrations compared to their wild-type parent. Furthermore, overproduction of Dps during growth phase resulted in decreased intracellular copper content under copper stress. [Copyright &y& Elsevier]

Technical limitations restrict routine anaerobe isolation from clinical materials in resource-limited laboratories. An innovative two steps combustion candle jar technique may be suitable for such setup. This system was tried with one case of chronic osteomyelitis developed on supracondyler compound fracture. Porphyromonas spp. was isolated and identified. Vancomycin was recommended based on in vitro sensitivity test, but the leg was amputed after receiving a resistant drug gentamycin. While in another child with hydrocephalous, V-P shunt associated infection by Peptostreptococcus anaerobius was successfully controlled by sensitive drug vancomycin. These two eye-opener cases insisted us for large scale application of the technique. [ABSTRACT FROM AUTHOR]

Abstract: The spreading of vinasse may favour soil anoxia and affect cation exchange capacity (CEC). Our aims were to assess the reliability of CEC measurements in reducing conditions, quantify CEC variations in a ferralsol under changing aeration conditions, and understand the mechanisms involved. In a first experiment, soil slurry was incubated for a succession of 7 oxic, 28 anoxic and 28 oxic days, vinasse being supplied when anoxia began. CEC was measured at intervals by exchanging Mg2+, Cu-trien or Co(NH3)6 3+, the solutions being characterized before and after exchange. In a second experiment, soil CEC was measured after the elution of NH4 + solutions of pH 5 to 7. In a third experiment, we assessed the reduction of Co(NH3)6 3+ by Fe2+ and checked for induced changes by geochemical simulations. During the first oxic period, CEC varied according to method, in the order: Cu-trien

Horizontal gene transfer (HGT) is known to have contributed to the content of eukaryotic genomes, but the direct effects of HGT on eukaryotic evolution are more obscure because many of the best supported cases involve a new gene replacing a functionally similar homologue. Here, several cases of HGT conferring a plausible adaptive advantage are reviewed to examine emerging trends in such transfer events. In particular, HGT seems to play an important role in adaptation to parasitism and pathogenesis, as well as to other specific environmental conditions such as anaerobiosis or nitrogen and iron limitation in marine environments. Most, but not all, of the functionally significant HGT to eukaryotes comes from bacteria, in part due to chance, but probably also because bacteria have greater metabolic diversity to offer. [Copyright &y& Elsevier]

To detect anoxygenic bacteria containing either type 1 or type 2 photosynthetic reaction centers in a single PCR, we designed a degenerate primer set based on the bchY gene. The new primers were validated in silico using the GenBank nucleotide database as well as by PCR on pure strains and environmental DNA. [ABSTRACT FROM AUTHOR]

The article presents a study which evaluates the oxidative stress responses of Streptococcus pneumoniae and define a role for Rgg in the pneumococcus. It determines the oxidative adaptation of S. pneumoniae through the global gene profile of the microorganism in aerobiosis and anaerobiosis while relation of Rgg in pneumococcal oxidative adaptation was found by constructing an isogenic mutant. The results indicate that the S. pneumonia oxidative response is not limited to gene expression.

The article reports that Vitamin B1 is in its active form thiamine pyrophosphate (TPP), an essential cofactor for several key enzymes in the carbohydrate metabolism. It is mentioned that mammals need to salvage crucial nutrient from their diet in order to complement the deficiency of de novo synthesis. In the human pathogenic bacterium Staphylococcus aureus, two operons were identified which are involved in vitamin B1 metabolism. It is mentioned that the kinetic properties of the enzymes as well as the binding of TPP to the in vitro transcribed RNA of the proposed operons suggest that the vitamin B1 homeostasis in S. aureus is strongly regulated at transcriptional as well as enzymatic levels.

Benthic marine organisms such as mollusks are often exposed to periodic oxygen deficiency (due to the tidal exposure and/or seasonal expansion of the oxygen-deficient dead zones) and pollution by metals [e.g., cadmium, (Cd)]. These stressors can strongly affect mollusks' survival; however, physiological mechanisms of their combined effects are not fully understood. We studied the effects of Cd exposure on metabolic responses to prolonged anoxia and subsequent recovery in anoxia-tolerant intertidal mollusks Crassostrea virginica (eastern oysters). Anoxia led to an onset of anaerobiosis indicated by accumulation of L-alanine, acetate, and succinate. Prolonged anoxia (for 6 days) caused a decline in the maximum activity of electron transport chain and ADP-stimulated (state 3) oxygen uptake by mitochondria (MO2), but no change in the resting (state 4) MO2 of oyster mitochondria, along with a slight but significant reduction of mitochondrial respiratory control ratio. During reoxygenation, there was a significant overshoot of mitochondrial MO2 (by up to 70% above the normoxic steady-state values) in control oysters. Mild mitochondrial uncoupling during prolonged shutdown in anoxic tissues and a subsequent strong stimulation of mitochondrial flux during recovery may help to rapidly restore redox status and protect against elevated reactive oxygen species formation in oysters. Exposure to Cd inhibits anaerobic metabolism, abolishes reoxygenation-induced stimulation of mitochondrial MO2, and leads to oxidative stress (indicated by accumulation of DNA lesions) and a loss of mitochondrial capacity during postanoxic recovery. This may result in increased sensitivity to intermittent hypoxia and anoxia in Cd-exposed mollusks and will have implications for their survival in polluted estuaries and coastal zones. [ABSTRACT FROM AUTHOR]

Ducks are well-known to be more tolerant to asphyxia than non-diving birds, but it is not known if their defences include enhanced neuronal hypoxia tolerance. To test this, we compared extracellular recordings of spontaneous activity in the Purkinje cell layer of 400 μm thick isolated cerebellar slices from eider ducks, chickens and rats, before, during and after 60 min hypoxia (95%N2–5%CO2) or chemical anoxia (hypoxia + 2 mM NaCN). Most slices rapidly lost activity in hypoxia, with or without recovery after rinse and return to normoxia (95%O2–5%CO2), but some maintained spontaneous activity throughout the insult. Proportions of ‘surviving’ (i.e. recovering or active) duck slices were significantly higher than for chickens in anoxia, and relative activity levels were higher for ducks than for chickens during hypoxia, anoxia and recovery. Survival of rat slices was significantly poorer than for birds under all conditions. Results suggest that (1) duck cerebellar neurons are intrinsically more hypoxia-tolerant than chicken neurons; (2) avian neurons are more hypoxia-tolerant than rat neurons, and (3) the enhanced hypoxic tolerance of duck neurons largely depended on efficient anaerobiosis since it mainly manifested itself in chemical anoxia. Mechanisms underlying the observed differences in neuronal hypoxic responses remain to be elucidated. [ABSTRACT FROM AUTHOR]

The spreading of vinasse on soils may favor not only anoxia but also mineral alterations and metal mobilization. Our aims were to record the geochemical changes occurring in a ferralsol subjected to vinasse input and anaerobiosis, and to check for soil resilience after a return to aerobic conditions. Soil slurries were therefore incubated under successive 7 d of aerobic, 0 to 28 d of anaerobic, and 28 d of aerobic conditions, vinasse being supplied at one of three levels when anaerobiosis began. At several dates, the slurry solution was characterized (pH and organic and mineral compounds) and Mn and Fe oxidation states in solids were assessed. Before incubations, about 20% ofthe Fe in solids was already reduced, whereas almost all Mn was found as Mn(IV). During the first aerobic period, mobilized metals included Pb, Zn, Ni, Cu, and Cr. After vinasse input during the first 14 d of anaerobiosis, the principal biotransformations were fermentation and true acetogenesis; Fe and Mn were mobilized during this period (up to 4.05 and 6.2 mmol L-1, respectively), and most Mn and an unknown but small fraction of Fe in solids were reduced. During the subsequent 14 d of anaerobiosis, only acetoclastic methanogenesis was observed. The return to aerobic conditions led to rapid oxidative immobilization of Fe, desorption of exchangeable Fe(II), and the partial immobilization of other metals (Ca, Mg, K, Na, Mn, Pb, and Ni). Manganese was not oxidized, and there was no return to the initial conditions for Fe and Mn in solids. [ABSTRACT FROM AUTHOR]

The phage shock protein (Psp) system found in enterobacteria is induced in response to impaired inner membrane integrity (where the Psp response is thought to help maintain the proton motive force of the cell) and is implicated in the virulence of pathogens such as Yersinia and Salmonella. We provided evidence that the two-component ArcAB system was involved in induction of the Psp response in Escherichia coli and now report that role of ArcAB is conditional. ArcAB, predominantly through the action of ArcA regulated genes, but also via a direct ArcB–Psp interaction, is required to propagate the protein IV (pIV)-dependent psp-inducing signal(s) during microaerobiosis, but not during aerobiosis or anaerobiosis. We show that ArcB directly interacts with the PspB, possibly by means of the PspB leucine zipper motif, thereby allowing cross-communication between the two systems. In addition we demonstrate that the pIV-dependent induction of psp expression in anaerobiosis is independent of PspBC, establishing that PspA and PspF can function as a minimal Psp system responsive to inner membrane stress. [ABSTRACT FROM AUTHOR]

Abstract: Nonlinear dynamics is ubiquitous in engineering systems. As some parameters are varied bifurcations arise in the state variables. Generically, when one parameter changes, Hopf and fold bifurcations are found. Other ones can also be present due to special systems characteristics, such as symmetries. Knowing in advance the significant bifurcation scenario, a novel approach to control can be considered. We compute the normal form corresponding to such a bifurcation and we take this model as the nominal model of the plant. Then we design a nonlinear control which takes advantage of the precise bifurcation scenario. This general method is applied, in this paper, to an anaerobic digester. We will control the process with an adaptive controller. Specifically, we want to compare with the case that the nominal plant is considered as a linear model, such as it is typical in adaptive control techniques. Our proposed method has more benefits in signal control effort, faster convergence rate and low error. This paper shows how the combination of appropriated nonlinear dynamic techniques such as bifurcations and normal forms, and nonlinear control, can give rise to an improvement of the traditional methodology. [Copyright &y& Elsevier]

Analysis reveals that there is limited overlap in the sets of transcripts that show significant changes in abundance during anaerobiosis in different plant species. This may be due to the fact that a combination of primary effects, changes due to the presence or absence of oxygen, and secondary effects, responses to primary changes or tissue and developmental responses, are measured together and not differentiated from each other. In order to dissect out these responses, the effect of the presence or absence of oxygen was investigated using three different experimental designs using rice (Oryza sativa) as a model system. A total of 110 metabolites and 9,596 transcripts were found to change significantly in response to oxygen availability in at least one experiment. However, only one-quarter of these showed complementary responses to oxygen in all three experiments, allowing the core response to oxygen availability to be defined. A total of 10 metabolites and 1,136 genes could be defined as aerobic responders (up-regulated in the presence of oxygen and down-regulated in its absence), and 13 metabolites and 730 genes could be defined as anaerobic responders (up-regulated in the absence of oxygen and down-regulated in its presence). Defining core sets of transcripts that were sensitive to oxygen provided insights into alterations in metabolism, specifically carbohydrate and lipid metabolism and the putative regulatory mechanisms that allow rice to grow under anaerobic conditions. Transcript abundance of a specific set of transcription factors was sensitive to oxygen availability during all of the different experiments conducted, putatively identifying primary regulators of gene expression under anaerobic conditions. Combined with the possibility of selective transcript degradation, these transcriptional processes are involved in the core response of rice to anaerobiosis. [ABSTRACT FROM AUTHOR]

Abstract: Listeria adhesion protein (LAP), an alcohol acetaldehyde dehydrogenase homolog (lmo1634) in Listeria monocytogenes, promotes bacterial adhesion to intestinal epithelial cells in vitro. Investigation of the effect of anaerobiosis, an intrinsic gastrointestinal condition, on LAP expression and LAP-mediated infection should elucidate its significance during intestinal infection. The influence of anaerobiosis on LAP expression was determined by growing L. monocytogenes wild type (WT), and lap-deficient (KB208) and -complemented (CKB208) strains anaerobically and monitoring LAP in secreted, cell wall, and whole-cell protein fractions. The effect of anaerobiosis on LAP-mediated infection was evaluated in cell culture adhesion assays and mouse infection models. Additionally, the role of secretory system SecA2 in LAP secretion was investigated. Anaerobic growth induced significant increases in level of lap transcript and protein secretion, and secretion was SecA2-dependent. Anaerobiosis facilitated greater LAP-mediated adhesion of L. monocytogenes to cultured intestinal cells. Oral administration of WT, KB208 and CKB208 to mice confirmed that LAP is essential for full virulence, and anaerobically-grown WT exhibited greater translocation to liver and spleen relative to aerobically-grown organisms. LAP, a SecA2-dependent secreted virulence factor, plays an important role during intestinal infection, particularly when L. monocytogenes is subjected to an anaerobic environment. [Copyright &y& Elsevier]

Bacteria have evolved different systems to tightly control both cytosolic and envelope copper concentration to fulfil their requirements and at the same time, avoid copper toxicity. We have previously demonstrated that, as in Escherichia coli, the Salmonella cue system protects the cytosol from copper excess. On the other hand, and even though Salmonella lacks the CusCFBA periplasmic copper efflux system, it can support higher copper concentrations than E. coli under anaerobic conditions. Here we show that the Salmonella cue regulon is also responsible for the control of copper toxicity in anaerobiosis. We establish that resistance in this condition requires a novel CueR-controlled gene named cueP. A Δ cueP mutant is highly susceptible to copper in the absence of oxygen, but shows a faint phenotype in aerobic conditions unless other copper-resistance genes are also deleted, resembling the E. coli CusCFBA behaviour. Species that contain a cueP homologue under CueR regulation have no functional CusR/CusS-dependent Cus-coding operon. Conversely, species that carry a CusR/CusS-regulated cus operon have no cueP homologues. Even more, we show that the CueR-controlled cueP expression increases copper resistance of a Δ cus E. coli. We posit that CueP can functionally replace the Cus complex for periplasmic copper resistance, in particular under anaerobic conditions. [ABSTRACT FROM AUTHOR]

Abstract: The optimization of total solids in the feed (%TS) and alkalinity ratio (γ) for H2 production from organic solid wastes under thermophilic regime was carried out using response surface methodology based on a central composite design. The total solids levels were 20.9, 23.0, 28.0, 33.0 and 35.1% whereas the levels of alkalinity ratio (defined as g phosphate alkalinity/g dry substrate) were 0.15, 0.20, 0.30, 0.41 and 0.45. High levels of TS and γ affected in a negative way the H2 productivity and yield; both response variables significantly increased upon decreasing the TS content and alkalinity ratio. The highest H2 productivity and yield were 463.7NmL/kg-d and 54.8NmL/gVSrem, respectively, predicted at 20.9% TS and alkalinity ratio 0.25 (0.11gCaCO3/g dry substrate). The alkalinity requirements for hydrogenogenic processes were lower than those reported for methanogenic processes (0.11 vs. 0.30gCaCO3/gCOD). Adequate alkalinity ratio was necessary to maintain optimal biological activity for hydrogen production; however, excessive alkalinity negatively affected process performance probably due to an increase of osmotic pressure. Interestingly, reactor pH depended only on the alkalinity ratio, thus the buffer capacity was able to maintain a constant pH independently of TS levels. At γ =0.15–0.30 the pHs were in the range 5.56–5.95, which corresponded to the highest hydrogen productivities and yields. Finally, the highest metabolite accumulation corresponded with the highest removal efficiencies but not with high H2 productivities and yields. Therefore, it seems that organic matter removal was channeled toward solvent generation instead of hydrogen production at high TS and γ levels. This is the first study that shows the requirements of alkalinity in solid substrate fermentation conditions for H2 production processes and their interaction with the content of total solids in the feed. [Copyright &y& Elsevier]

Introduction Wingate anaerobic test is an all-out test, which gives information about maximal anaerobic power. The aim of the study was to show characteristics of standard and modified versions of Wingate anaerobic test (WAnT), and to determine and explain the differences in observed parameters due to the measurement protocol applied. Matherial and methods The testing was conducted on 30 male non sportsmen, who performed usual everyday activities. The following parameters were measured: peak power or anaerobic power, mean power as a mean value of power during the whole test and explosive power or acceleration. Modified versions were performed with 5 s or 10 s delay of maximal cycling activity, during which the person was slowly pedaling. Results The average values of parameters Peak power and Explosive power in our participants were 622.20±134.57 W and 89.26 ±28.57 W/s, respectively. In modification 1 Peak Power and Explosive Power were 680.25±133.43 W and 100.60±12.77 W/s, and in modification 2 they were 685.95±135.68 W and 100.30±10.09 W/s. Significant differences were found in both parameters between the standard and modified versions, but there was no significant difference between two modified versions. The mean power parameter was not considered in the discussion, because of the fact that modified versions were shortened, and it was not a valid measurement for this parameter. Discusion and conclusion The difference between standard and modified versions can be explained by the difference between test and retest probes, and also because of modification of protocol which can partially influence the results of testing. [ABSTRACT FROM AUTHOR]

The transcriptional activator Gcn4p is considered the master regulator of amino acid metabolism in Saccharomyces cerevisiae and is required for the transcriptional response to amino acid starvation. Here it is shown that Gcn4p plays a previously undescribed role in regulating adaptation to anaerobic growth. A gcn4 mutant exhibited a highly extended lag phase after a shift to anaerobiosis that was the result of L-serine depletion. In addition, the one-carbon metabolism and purine biosynthesis transcriptional regulator Bas1p were strictly required for anaerobic growth on minimal medium, and this was similarly due to L-serme limitation in bas1 mutants. The induction of one-carbon metabolism during anaerobiosis is needed to increase the supply of L-serine from the glycine and threonine pathways. Using a number of experimental approaches, we demonstrate that these transcription regulators play vital roles in regulating L-serine biosynthesis in the face of increased demand during adaptation to anaerobiosis. This increased L-serine requirement is most likely due to anaerobic remodeling of the cell wall, involving de novo synthesis of a large number of very serine-rich mannoproteins and an increase in the total serine content of the cell wall. During anaerobic starvation for L-serine, this essential amino acid is preferentially directed to the cell wall, indicating the existence of a regulatory mechanism to balance competing cellular demands. [ABSTRACT FROM AUTHOR]

Abstract: Calli induced from Solanum torvum stem explants were inoculated with Ralstonia solanacearum under partial vacuum. All calli showed a hypersensitive response after infiltration. Furthermore, amine oxidase activity with aldehyde and H2O2 production was detected in semi-purified cell walls of calli infiltrated by the bacteria. Due to its preferential affinity for monoamines, this enzyme is supposed to have monoamine oxidase-like (MAO-like) activity. Moreover, the presence of hydroxyl radicals in the aromatic cycle alters the oxidative deamination kinetics of potential substrates. Indeed, the oxidation of dopamine (+2, OH) was shown to be faster than that of tyramine (+1, OH), which in turn was faster than that of phenylethylamine (0, OH). The MAO-like catalytic activity was significantly inhibited by some reducing agents such as sodium bisulphite and cysteine, and also by tryptamine under anaerobiosis. This latter result suggested that the prosthetic group of the MAO-like enzyme could be a tyrosine-derived 6-hydroxytopaquinone structure. Finally, the sigmoid kinetics of the MAO-like enzyme in semi-purified cell walls did not correspond to that expected for a purified MAO, suggesting that the kinetics were affected by some factors present in cell walls. [Copyright &y& Elsevier]

Pasteurized and unfermented milks supplemented with probiotic bacteria are appearing on the market. It then becomes a challenge to ascertain the undesirable contamination microbiota in the presence of a largely superior population of probiotic bacteria. A method to enumerate the contaminating microbial microbiota in such probiotic-enriched milks was developed. The probiotic cultures, Lactobacillus rhamnosus Lb-Immuni-T™ and Bifidobacterium animalis subsp. lactis BB-12®, were added to a pasteurized unfermented milk to reach a minimum of 1 billion CFU per 250 mL portion, as ascertained by plating on de Man - Rogosa - Sharpe (MRS) agar in anaerobic conditions. No growth of B. animalis subsp. lactis BB-12 was noted on plate count agar (PCA) or Petrifilm™ plates, and the presence of this culture did not affect standard plate counts (SPC) of contaminating bacteria. However, L. rhamnosus formed colonies on PCA and Petrifilm™ plates. Attempts were thus made to inhibit the growth of the probiotic lactobacilli in PCA. The addition of 2% sodium phosphate (SP) or 5% glycerophosphate (GP) inhibited the growth of the lactobacilli in broths, but pin-point colonies of L. rhamnosus Lb-Immuni-T nevertheless appeared on PCA supplemented with phosphates. SPC could be obtained on PCA + 2% SP by only counting the large colonies, but this resulted in a significant (4.4 fold) underestimation of SPC values. On Petrifilm™ AC, at dilutions 0 to 2, all colonies were considered as being contaminants, while at dilutions 3 and 4, only large colonies were counted for SPC determinations. There was a direct correlation (R2 = 0.99) between SPC values with Petrifilm™ in uninoculated milks and those obtained on probiotic-enriched milks. The high correlation obtained over the 102 to 106 CFU/mL range of SPC values show that this Petrifilm™ method is appropriate to evaluate the microbiological quality of pasteurized milks enriched with L. rhamnosus Lb-Immuni-T and B. animalis subsp. lactis BB-12. [ABSTRACT FROM AUTHOR]

The feasibility of long-term (>3 years), low-temperature (4–15°C) and anaerobic bioreactor operation, for the treatment of acidified wastewater, was investigated. A hybrid, expanded granular sludge bed–anaerobic filter bioreactor was seeded with a mesophilic inoculum and employed for the mineralization of moderate-strength (3.75–10kg chemical oxygen demand (COD)m−3) volatile fatty acid-based wastewaters at 4–15°C. Bioprocess performance was assessed in terms of COD removal efficiency (CODRE), methane biogas concentration, and yield, and biomass retention. Batch specific methanogenic activity assays were performed to physiologically characterise reactor biomass. Despite transient disimprovements, CODRE and methane biogas concentrations exceeded 80% and 65%, respectively, at an applied organic loading rate (OLR) of 10kgCODm−3 d−1 between 9.5 and 15°C (sludge loading rate (SLR), 0.6kgCODkg[VSS]−1 d−1). Over 50% of the granular sludge bed was lost to disintegration during operation at 9.5°C, warranting a reduction in the applied OLR to 3.75–5kgCODm−3 d−1 (SLR, c. 0.4–0.5kgCODkg[VSS]−1 d−1). From that point forward, remarkably stable and efficient performance was observed during operation at 4–10°C, with respect to CODRE (≥82%), methane biogas concentration (>70%) and methane yields (>4lMethane d−1), suggesting the adaptation of our mesophilic inoculum to psychrophilic operating conditions. Physiological activity assays indicated the development of psychroactive syntrophic and methanogenic populations, including the emergence of putatively psychrophilic propionate-oxidising and hydrogenotrophic methanogenic activity. The data suggest that mesophilic inocula can physiologically adapt to sub-optimal operational temperatures: treatment efficiencies and sludge loading rates at 4°C (day, 1243) were comparable to those achieved at 15°C (day 0). Furthermore, long-term, low-temperature bioreactor operation may act as a selective enrichment for psychrophilic methanogenic activity from mesophilic inocula. The observed efficient and stable bioprocess performance highlights the potential for long-term, low-temperature bioreactor operation. [Copyright &y& Elsevier]

Waterlogging is a serious problem which affects crop growth and yield in low-lying, rainfed areas. Most of the rainy-season crops, especially legumes, and to a lesser extent maize and rice are affected by flooding leading to hypoxic or even anoxic conditions. Lack of oxygen shifts the energy metabolism from aerobic mode to anaerobic mode, which in turn adversely affects nutrient and water uptake; so the plants show wilting even when surrounded by excess water. Gaseous plant hormone ethylene plays an important role in modifying the plant's response to oxygen deficiency. Plants normally adapted to growing under waterlogged conditions have mechanisms to cope with this stress in the form of aerenchyma formation, increased availability of soluble sugars, greater activity of glycolytic pathway and fermentation enzymes. Both alcoholic and lactic acid fermentation help in maintaining lower redox potential (low NADH/NAD ratio), and thereby play an important role in anaerobic stress tolerance. Other important biomolecules which are induced under waterlogging, are nonsymbiotic haemoglobins and nitric oxide. Interaction of nonsymbiotic haemoglobins and nitric oxide has been suggested as an alternative to the fermentation pathway, which also rules out the production of toxic alcohol and lactic acid, the latter being the major cause of cytoplasmic acidosis. Waterlogging stress also results in the production of reactive oxygen species, and induction of antioxidant defence enzymes. Waterlogging-induced production of ethylene, H2O2 and NO is also involved in signalling and induction of various defence-related genes leading to synthesis of proteins/enzymes imparting hypoxia tolerance. [ABSTRACT FROM AUTHOR]

Though the affinity of iron oxides and hydroxides for phosphorus (P) is thought to limit growth and productivity of plants on iron-rich acidic soils in humid tropical climate, tall trees are found in tropical rainforests, and vigorous growth occurs in herbaceous vegetation in the humid tropical climate of the Andamans. Our study reports how high rainfall influences Bray and Kurtz P-1 extractable P, water filled pore space (WFPS), microbial biomass carbon (MB-C) and phosphorus (MB-P) in the gravelly-sandy-loamy soils in three major land use systems: moist-evergreen forest, semi-evergreen forest and homegarden, in the equatorial humid tropical climate of South Andaman island of India. In addition, an ex-situ experiment investigated how labile carbon (glucose) under different soil-water regimes [25% field capacity (FC) and 100% FC] affected the P in the soils under the land use systems. WFPS, across the land use systems, was more than two times higher during the high rainfall than dry spell (72–80 hr after the high rainfall). The extractable P, across the land use systems, increased about 5 to 6 fold during the high rainfall than dry spell. The increase was the highest in the homegarden and lowest in moist-evergreen forest. The extractable P was positively correlated with the WFPS. MB-C and MB-P were lower during the high rainfall than dry spell in all the land use systems. In the ex-situ experiment, the extractable P increased 1.4 to 1.7 fold more in water (100% FC) + glucose than water (100% FC) alone treatment. Water at 25% FC did not increase the extractable P in the soils under all the land use systems. After cessation of the high rainfall, WFPS declined quickly within 2-hr in the upper layer (0–5 cm) of the soils. These indicate that the high rainfall together with labile carbon increases the extractable P through anaerobiosis, whereas, quick decline in the WFPS (0–5 cm) following cessation of the high rainfall helps its uptake by plants and microflora. [ABSTRACT FROM AUTHOR]

Background: The Escherichia coli heterodimeric HU protein is a small DNA-bending protein associated with the bacterial nucleoid. It can introduce negative supercoils into closed circular DNA in the presence of topoisomerase I. Cells lacking HU grow very poorly and display many phenotypes. Methodology/Principal Findings: We analyzed the transcription profile of every Escherichia coli gene in the absence of one or both HU subunits. This genome-wide in silico transcriptomic approach, performed in parallel with in vivo genetic experimentation, defined the HU regulon. This large regulon, which comprises 8% of the genome, is composed of four biologically relevant gene classes whose regulation responds to anaerobiosis, acid stress, high osmolarity, and SOS induction. Conclusions/Significance: The regulation a large number of genes encoding enzymes involved in energy metabolism and catabolism pathways by HU explains the highly pleiotropic phenotype of HU-deficient cells. The uniform chromosomal distribution of the many operons regulated by HU strongly suggests that the transcriptional and nucleoid architectural functions of HU constitute two aspects of a unique protein-DNA interaction mechanism. [ABSTRACT FROM AUTHOR]

Abstract: We have found the transcript of one of at least six ferredoxin encoding genes of the green alga Chlamydomonas reinhardtii, FDX5, strongly accumulating in anaerobiosis, indicating a vital role of the encoded protein in the anaerobic metabolism of the cells. According to absorption and electron paramagnetic resonance spectroscopy, Fdx5 is a plant-type [2Fe2S]-ferredoxin with a redox potential similar to that of the ferredoxin PetF. However, although Fdx5 seems to be located in the chloroplast, it is not able to photoreduce nicotinamide adenine dinucleotide phosphate (NADP+) via ferredoxin-NADP-reductase, nor to be an electron donor to the plastidic [FeFe]-hydrogenase HydA1. Thus, Fdx5 seems to have a special role in a yet to be identified anaerobic pathway. [Copyright &y& Elsevier]

Background and Aims: The lack of knowledge about key traits in field environments is a major constraint to germplasm improvement and crop management because waterlogging-prone environments are highly diverse and complex, and the mechanisms of tolerance to waterlogging include a large range of traits. A model is proposed that waterlogging tolerance is a product of tolerance to anaerobiosis and high microelement concentrations. This is further evaluated with the aim of prioritizing traits required for waterlogging tolerance of wheat in the field. [ABSTRACT FROM PUBLISHER]

Abstract: Pathogenesis of the facultative anaerobe Vibrio cholerae takes place at the gut under low oxygen concentrations. To identify proteins which change their expression level in response to oxygen availability, proteomes of V. cholerae El Tor C7258 grown in aerobiosis, microaerobiosis and anaerobiosis were compared by two-dimensional electrophoresis. Twenty-six differentially expressed proteins were identified which are involved in several processes including iron acquisition, alanine metabolism, purine synthesis, energy metabolism and stress response. Moreover, two proteins implicated in exopolysaccharide synthesis and biofilm formation were produced at higher levels under microaerobiosis and anaerobiosis, which suggests a role of oxygen deprivation in biofilm development in V. cholerae. In addition, six proteins encoded at the Vibrio pathogenicity island attained the highest expression levels under anaerobiosis, and five of them are required for colonization: three correspond to toxin-coregulated pilus biogenesis components, one to soluble colonization factor TcpF and one to accessory colonization factor A. Thus, anaerobiosis promotes synthesis of colonization factors in V. cholerae El Tor, suggesting that it may be a key in vivo signal for early stages of the pathogenic process of V. cholerae. [Copyright &y& Elsevier]

In this study, the method of using high concentrated oxygen water to purify the bottom sediment was confirmed to be effective. The high concentrated oxygen dissolver was developed and the lab scale experiment was performed. High rate, high efficiency oxygen dissolver was developed, the optimum running condition of the apparatus and the method of producing high concentrated oxygen water was discussed and determined in this study. In addition, the effective prevention of phosphorus release from anaerobic bottom sediment was also studied. As a result, it is found that high concentrated oxygen water was effective for prevention of phosphorus release from anaerobic bottom sediment. On the basis of the fundamental knowledge from the laboratory-scale study, pilot scale apparatus was set up and the pilot study was carried out. It is showed that the introduction of high concentrated oxygen water did not destroy the thermocline of dam reservoir. [ABSTRACT FROM AUTHOR]

Transcript quantification techniques usually rely on purified mRNAs. We report here a solution-based sandwich hybridization assay for the quantification of mRNAs from Escherichia coli without the need of prior RNA isolation. This assay makes use of four DNA oligonucleotide probes adjacently hybridizing to target RNA in clarified cell extracts. Two helper probes facilitate the hybridization of a detection and a capture probe. The latter is biotin labeled, allowing binding to streptavidin-coated paramagnetic beads and the separation of the RNA-DNA hybrid from cellular constituents. Added antidigoxigenin Fab fragments conjugated to alkaline phosphatase bind to the digoxigenin-labeled detection probe, completing the sandwich of the paramagnetic bead, mRNA, probes, and alkaline phosphatase. The target transcript can be quantified by assessing phosphatase activity on a substrate that is converted into a fluorescent product. The amount of target mRNA is calculated from the fluorescence output and from a calibration curve for a known concentration of in vitro-synthesized target mRNA. This technique was used in time course experiments to investigate the expression of three genes responsible for the copper resistance of E. coli. The induction of gene expression by copper cations was rapid, but under aerobic conditions, the levels of expression returned to low, prestress levels within minutes. In anaerobiosis, high-level expression continued for at least 1 h. When cultures were shifted from anaerobiosis to aerobiosis, expression levels were diminished within minutes to prestress levels. The improved technique presented here is relatively simple, has very high degrees of sensitivity and robustness, is less laborious than other RNA quantification methods, and is not negatively affected by genomic DNA. These characteristics make it a powerful complementary application to genetic reporter fusions and to reverse transcription.PCR. [ABSTRACT FROM AUTHOR]

Growing interest has been shown in the continuous production of high-value products such as extracellular secondary metabolites used in the biotechnology, bioremediation and pharmaceutical industries. These high-value extracellular secondary metabolites are mostly produced in submerged fermentations. However, the use of continuous membrane bioreactors was determined to be highly productive. A novel membrane bioreactor, classified as a membrane gradostat reactor (MGR) was developed to immobilize biofilms to produce extracellular secondary metabolites continuously using an externally unskinned and internally skinned membrane. Anaerobic zones were identified in the MGR system when air was used for aeration. To improve the MGR system, limitations related to the performance of the bioreactor were determined using P. chrysosporium. A DO penetration depth of ±450μm was identified after 264 h, with the anaerobic zone thickness reaching ~1,943μm in the immobilised biofilms. The penetration ratio, decreased from 0.42 after 72 h to 0.14 after 264 h. This led to the production of ethanol in the range of 10 to 56 mg/L in the MCMGR and 7 to 54 mg/L in SCMGR systems. This was attributed to an increase in β-glucan within immobilised biofilms when an oxygen enriched aeration source was used. Increasing lipid peroxidation and trace element accumulation was observed with the use of an oxygen enriched aeration source. [ABSTRACT FROM AUTHOR]

Abstract: Intestinal microbes live in diminished or deprived oxygen conditions. Facultative anaerobic bacteria of the family Enterobacteriaceae ferment glucose in the gut using two main pathways: mixed acid and neutral fermentations. The aim of the present study was to clarify the roles of these fermentations in an in vitro model. Acid-producing Escherichia coli ATCC 25922 and neutral end-products producing Klebsiella mobilis ATCC 13048 were cultured in a Portable Microbe Enrichment Unit (PMEU) which permitted the selection of the gas phase in standardized conditions. In the butanediol production experiments also Klebsiella pneumoniae ssp. pneumoniae IIIa2 E111 strain was also used. Two isomers of 2,3-butanediol were observed in both aerobic and microaerobic Klebsiella cultures. During 7h cultures both E. coli and K. mobilis grew from densities of some million up to some billions per ml. The growth was almost equal in both aerobic and microaerobic conditions. In anaerobic conditions a balance prevailed in mixed E. coli and Klebsiella cultures between the species (final pH was 5.8–6.1), whereas in aerobic conditions the klebsiellas were favoured, and the pH rose up to about 8.5 (in 20h) as in pure Klebsiella cultures. In microaerobic Klebsiella cultures the final pH varied between 6.7 and 7.5. In mixed cultures the growth yields of both bacteria equalled those of the separate pure cultures indicating mutual benefits of the co-existence. Apparently E. coli produced a set of organic acids, which lowered pH. Klebsiellas increased the pH up to 2units probably due to acid conversion in anaerobic conditions to ethanol. We propose that the balance of acid and ethanol as well 2,3-butanediol fermentations contributes to the small bowel pH regulation, which also aids the host in the nutrient uptake in the small intestine. [Copyright &y& Elsevier]

The article provides information on a study concering transcription regulator AIIR. It is stated that purines are degraded through uric acid to yield allantoin. Within anaerobic conditions, allantoin is entirely reduced via carbamoylphosphate to render a nitrogen source. Carbamolyphosphate is also processed to 3-phosphoglycerate via glyoxylate for energy production. The research found out that the DNA-binding transcription factor AIIR, together with the AIIS, plays a relevant role in switching control of two pathways which are nitrogen assimilation and energy production. AIIR has been found to sense both allantoin and glyoxylate and controls a set of genes for the degradation and reutilization of purines.

Abstract: Microbial fermentation is a potentially important member of a diverse portfolio of methods available for renewable production of hydrogen using biomass as a substrate. A major factor currently limiting commercial viability of fermentative hydrogen production is poor stoichiometric yield per mole of sugar and end-product feedback inhibition. Although several approaches have been tried to enhance microbial hydrogen productivity, genetic engineering technologies for most promising microorganisms are either unavailable or severely limited. Further efforts to overcome existing issues will need to rely on the ability to analyze, predict and engineer microbial metabolism in native H2-producing strains as well as genetically engineerable strains with constructed H2-metabolism. A shift in the type of biomass substrate from starch-based food crops to ligno-cellulosic crops and wastes that are economically and environmentally less costly to produce, yet more difficult to chemically and biologically process, presents technical challenges that are shared by all emerging biofuel technologies. A brief overview of the current status of fermentative H2-production, including a discussion of directly and indirectly related emerging technologies, is presented. [Copyright &y& Elsevier]

Two remarkable scientific events happened recently (Zaitsev, Polikarpov, Egorov et al., 2007, 2008) in the field of the newly developed deep-sea ecology and molismology of the hydrogen sulphide pelocontour in the Black Sea bathyal zone: - discoverys (in 2007) of viable spores of oxybionts in this aggressive zone against openly living oxybionts - those organisms which normally inhabit all three biocycles of the biosphere - the land, the fresh waters and the marine environment as well as - Determination (in 2008) of the safe sojourn duration of the oxybionts' spores by radioisotope dating in layers of the studied pelocontour sediment. Generalization and discussion of these events are presented. [ABSTRACT FROM AUTHOR]

Abstract: A comparative survey of the anaerobic survival potential of four different bivalve species and the interference of associated bacteria has been carried out. Individuals from both subtidal and intertidal environments were considered by selecting the following species: Mytilus edulis (subtidal epifaunal), Spisula subtruncata (subtidal infaunal), Macoma balthica (intertidal infaunal) and Cerastoderma edule (intertidal infaunal). Anaerobiosis was simulated in the laboratory by subjecting individuals to the following conditions: nitrogen atmosphere, air atmosphere and anoxic seawater incubation. Moreover, the effect of the antibiotic CA (chloramphenicol) was investigated, either as a pre-treatment of individuals kept under normoxic conditions for a week or directly added to the anoxic incubation media. According to survival performances of the individuals, intertidal animals that use to cope with tidal fluctuations in the coastline (emersion processes) had an extraordinary greater capacity to survive aerial exposure as compared to both nitrogen gas and anoxic seawater incubations most likely due to their capacity to perform aerobiosis at certain rate from atmospheric oxygen availability. Specifically, Macoma balthica enlarged its survival potential up to 24.8 days (LT50) under air exposure at 12 °C as compared to other specific treatments used here (4.9 days). The latter pattern was also observed, although in a much lower magnitude, for the other intertidal species Cerastoderma edule that survived 3.7 and 4.6 days (LT50) under nitrogen atmosphere and anoxic seawater incubation, respectively as compared to 9.5 days for emersed individuals. In contrast to the subtidal species, aerial exposure of both intertidal species led to a much higher survival performances than incubation of individuals in anoxic media with the presence of antibiotic. Survival capacity of the subtidal species Mytilus edulis and Spisula subtruncata was statistically similar under air and nitrogen atmospheres and anoxic seawater incubation. Then, subtidal species have a limited ability to air breathing as a conclusion of a similar survival in atmospheric and anoxic seawater incubations. Remarkably, M. edulis represented the only exception when considering longer-term survival capacity compared to the LT50 values. Indeed, differences in LT90 values for M. edulis were statistically different, values decreasing significantly from 19.7–19.9 days (under both nitrogen and air atmospheres) to 16.7 days when individuals are incubated in anoxic seawater. This may be due to the adverse effects of anaerobic bacteria that spontaneously proliferate within the static seawater incubations. As well as for S. subtruncata, possible aerobic processes under aerial exposure of mussels seemed to be not significant for the enlargement of its survival potential, since results obtained for both air and nitrogen atmospheres are similar. Pre-treatment with the antibiotic chloramphenicol caused survival capacity to increase by a factor of approx. 2 (M. edulis) and 34–44% (S. subtruncata). In contrast to intertidal species, the direct addition of the antibiotic to the incubation media caused the highest survival performances in both subtidal species. Habitat differences and species-dependent variability must be considered as significant sources of variation when studying the anaerobic performance of individuals using the most common experimental anaerobic techniques to test survival potential. [Copyright &y& Elsevier]

Abstract: The present study showed that the lactate/glucose ratio in the hemolymph of Chasmagnathus granulatus maintained in normoxia (controls) was 4.9, suggesting that lactate is an important substrate for this crab. Periods of hypoxia are part of the biological cycle of this crab, and lactate is the main end product of anaerobiosis in this crab. Our hypothesis was that this lactate would be, therefore, used by gluconeogenic pathway or can be oxidized or excreted to the aquatic medium during hypoxia and post-hypoxia periods in C. granulatus. The concentrations of hemolymphatic lactate in animals in normoxia are high, and are used as an energy substrate. In hypoxia, muscle gluconeogenesis and excretion of lactate to the aquatic medium would contribute significantly in regulating the concentration of circulating lactate. Utilization of these pathways would serve the objective of maintaining the acid-base equilibrium of the organism. Muscle gluconeogenesis participates, during the recovery process, in metabolizing the lactate produced during the period of hypoxia. Lactate excretion to the external medium, was one of the strategies used to decrease the higher hemolymphatic lactate levels. However, oxidation of lactate in the muscle is not a main strategy used by this crab to metabolize lactate in the recovery periods. [Copyright &y& Elsevier]

We report the synthesis and X-ray crystal structures of a series of pyridyl ureas of the type currently topical in anion binding and supramolecular gelation applications, along with their anion-binding ability in solution. The structures of the simple pyridyl ureas are dominated by urea···N(pyridyl) hydrogen bonding, because of steric congestion of the urea carbonyl by intramolecular CH···O interations. However, introducing a further competing synthon in the form of alkenic or π-stacking interactions causes a gradual changeover, through a number of interesting intermediate hydrogen bonding motifs, to the urea α-tape arrangement. [ABSTRACT FROM AUTHOR]

For decades altitude training has been used by endurance athletes and coaches to enhance sea-level performance. Whether altitude training does, in fact, enhance sea level performance and, if so, by what means has been the subject of a number of investigations. Data produced principally by Levine and Stray-Gundersen have shown that living for 4 weeks at 2500 m, while performing the more intense training sessions near sea level will provide an average improvement in sea level endurance performance (duration of competition: 7–20 min) of approximately 1.5%, ranging from no improvement to 6% improvement. This benefit lasts for at least 3 weeks on return to sea level. Two mechanisms have been shown to be associated with improvement in performance. One is an increase in red cell mass (∼8%) that results in an improved maximal oxygen uptake (∼5%). That must be combined with maintenance of training velocities and oxygen flux to realize the improvement in subsequent sea level performance. We find no evidence of changes in running economy or markers of anaerobic energy utilization. Our results have been obtained in runners ranging from collegiate to elite. Wehrlin et al. have recently confirmed these results in elite orienteers. While there are no specific studies addressing the use of living high, training low in football players, it is likely that an improvement in maximal oxygen uptake, all other factors equal, would enhance football performance. This benefit must be weighed against the time away (4 weeks) from home and competition necessary to gain these benefits. [ABSTRACT FROM AUTHOR]

With the use of technologically constructed hypoxic environments (TCHE) in soccer as our case, we propose four check points from which to evaluate new performance-enhancing technologies in sport. These are (I) Is the technology beneficial, (II) Is it safe, (III) Can fairness be assured, and (IV) Is the technology in line with the spirit of or rationale for sport? The use of TCHE is ambiguous. On the one hand, in situations with grave inequalities between teams due to lack of acclimatization of one team, TCHE can be an efficient means to even the playing field and out of concern for athlete welfare and health. On the other hand, if used as a pure performance-enhancing means to enhance the oxygen-carrying capacity of the blood independent of altitude, it belongs to a category of expert-assisted performance enhancement that may challenge athletic autonomy and the responsibility for one's own performance and, hence, the spirit of sport. [ABSTRACT FROM AUTHOR]

Heterotermes tenuis is a native termite of large negative impact on the Brazilian economy. Many studies have focused on optimizing the baiting method for termite control by improving its use and its efficacy. In order to maximize termite bait consumption, this study aimed to select nutrient solutions which are able to enhance termite feeding. The effects of some sugars and urea on feeding preference of the subterranean termite H. tenuis were determined by double choice feeding tests, and the consumption was evaluated by variation in dry mass of filter paper after 28 days of termite feeding. Most of the solutions tested did not significantly influence feeding of H. tenuis. Termites fed preferentially on filter paper treated with 0.03 g/ml trehalose and 0.015 g/ml urea solutions. The data indicate that trehalose and urea solutions are phagostimulants to H. tenuis, and their future use in bait matrices may increase consumption of baits and improve this control technique. [ABSTRACT FROM AUTHOR]

Abstract: In fungi, the velvet gene, or veA, is involved in the regulation of diverse cellular processes, including control of asexual and sexual development as well as secondary metabolism. This global regulator is conserved in numerous fungal species. Interestingly, in Aspergilli, where most of the studies on veA have been carried out, this gene has been described to mediate development in response to light. In recent years the knowledge of this important regulatory system has expanded through the use of Aspergillus nidulans as a model organism, and through the study of veA orthologs across fungal genera. This review includes information on the current understanding of veA function and its mechanism of action. The fact that veA has only been found in fungi, together with advances in the elucidation of the veA mechanism, might be useful in designing future control strategies to decrease the detrimental effects of fungi while enhancing those qualities that are beneficial. [Copyright &y& Elsevier]

A transition from oxidizing to reducing conditions has long been implicated to increase aqueous As concentrations, for which reductive dissolution of iron (hydr)oxides is commonly implicated as the primary culprit. Confounding our understanding of processes controlling As retention, however, is that reductive transformation of ferrihydrite has recently been shown to promote As retention rather than release. To resolve the role iron phases have in regulating arsenic concentrations, here we examine As desorption from ferrihydrite-coated sands presorbed with As(III); experiments were performed at circumneutral pH under Fe-reducing conditions with the dissimilatory iron reducing bacterium She wanella putrefaciens strain CN-32 over extended time periods. We reveal that with the initial phase of iron reduction, ferrihydrite undergoes transformation to secondary phases and increases As(III) retention (relative to abiotic controls). However, with increased reaction time, cessation of the phase transitions and ensuing reductive dissolution result in prolonged release of As(III) to the aqueous phase. Our results suggest that As(III) retention during iron reduction is temporally dependent on secondary precipitation of iron phases; during transformation to secondary phases, particularly magnetite, As(III) retention is enhanced even relative to oxidized systems. However, conditions that retard secondary transformation (more stable iron oxides or limited iron reducing bacterial activity), or prolonged anaerobiosis, will lead to both the dissolution of ferric (hydr)oxides and release of As(III) to the aqueous phase. [ABSTRACT FROM AUTHOR]

Abstract: The posterior cingulate cortex (PCC) is the brain region displaying the earliest sign of energy hypometabolism in patients with amnestic mild cognitive impairment (MCI) who develop Alzheimer’s disease (AD). In particular, the activity of the mitochondrial respiratory enzyme cytochrome oxidase (C.O.) is selectively inhibited within the PCC in AD. The present study is the first experimental analysis designed to model in animals the localized cortical C.O. inhibition found as the earliest metabolic sign of early-stage AD in human neuroimaging studies. Rats were used to model local inhibition of C.O. by direct injection of the C.O. inhibitor sodium azide into the PCC. Learning and memory were examined in a spatial holeboard task and brains were analyzed using quantitative histochemical, morphological and biochemical techniques. Behavioral results showed that sodium azide-treated rats were impaired in their memory of the baited pattern in probe trials as compared to their training scores before treatment, without non-specific behavioral differences. Brain analyses showed that C.O. inhibition was specific to the PCC, and sodium azide increased lipid peroxidation, gliosis and neuron loss, and lead to a network functional disconnection between the PCC and interconnected hippocampal regions. It was concluded that impaired memory by local C.O. inhibition in the PCC may serve to model in animals a metabolic lesion similar to that found in patients with amnestic MCI and early-stage AD. This model may be useful as an in vivo testing platform to investigate neuroprotective strategies to prevent or reduce the amnestic effects produced by posterior cingulate energy hypometabolism. [Copyright &y& Elsevier]

Abnormal neuronal signaling caused by metabolic changes characterizes several neurological disorders, and in some instances metabolic interventions provide therapeutic benefits. Indeed, altering metabolism either by fasting or by maintaining a low-carbohydrate (ketogenic) diet might reduce epileptic seizures and offer neuroprotection in part because the diet increases mitochondrial biogenesis and brain energy levels. Here we focus on a novel hypothesis that a ketogenic diet-induced change in energy metabolism increases levels of ATP and adenosine, purines that are critically involved in neuron–glia interactions, neuromodulation and synaptic plasticity. Enhancing brain bioenergetics (ATP) and increasing levels of adenosine, an endogenous anticonvulsant and neuroprotective molecule, might help with understanding and treating a variety of neurological disorders. [Copyright &y& Elsevier]

Lactobacillus rhamnosus R0011 was inoculated in an apple–pear–raspberry juice blend at 4.5 × 109 CFU/250 mL portion, and viability was followed during storage in conditions simulating consumer use. Study parameters were age of the juice (2 or 4 wk), sampling size (one to three 250-mL portions), incubation temperature (between 2 and 7 °C), and atmosphere (aerobic compared with anaerobic). Dependent variables were pH, dissolved oxygen (DO) level, and viable count. The DO level in the unopened PETE commercial bottles decreased from 10% to 3% over a 5-wk storage period at 7 °C. In shaken and opened bottles, DO increased to 15% during the 1st week of storage, irrespective of sampling size. However, agitation of bottles having more that 250 mL of headspace initially increased DO readings to 30% of maximum, but the DO level subsequently dropped to 15% during the 1-wk storage period between samplings. The presence of L. rhamnosus R0011 did not affect the DO data. The pH varied between 3.6 and 3.9, and was not influenced by L. rhamnosus R0011. However, the pH increased on average by 0.1 unit following multiple agitations and samplings. When the juices remained unopened in the PETE bottles, the viable population gradually dropped by 75% over 5 wk of storage at 7 °C, while in opened bottles reduction were only between 20% and 40%. Viability losses under anaerobic conditions were twice as high at 7 °C than at 4 °C. Data show that consumers can expect good viability of L. rhamnosus R0011 over a few weeks of storage in a refrigerator, even if the bottles have been opened and cells are exposed to oxygen. [ABSTRACT FROM AUTHOR]

There are two distinctly different pathways for the catabolism ofl-rhamnose in microorganisms. One pathway with phosphorylated intermediates was described in bacteria; here the enzymes and the corresponding gene sequences are known. The other pathway has no phosphorylated intermediates and has only been described in eukaryotic microorganisms. For this pathway, the enzyme activities have been described but not the corresponding gene sequences. The first enzyme in this catabolic pathway is the NAD-utilizingl-rhamnose 1-dehydrogenase. The enzyme was purified from the yeast Pichia stipitis, and the mass of its tryptic peptides was determined using MALDI-TOF MS. This enabled the identification of the corresponding gene, RHA1. It codes for a protein with 258 amino acids belonging to the protein family of short-chain alcohol dehydrogenases. The ORF was expressed in Saccharomyces cerevisiae. As the gene contained a CUG codon that codes for serine in P. stipitis but for leucine in S. cerevisiae, this codon has changed so that the same amino acid was expressed in S. cerevisiae. The heterologous protein showed the highest activity and affinity withl-rhamnose and a lower activity and affinity withl-mannose andl-lyxose. The enzyme was specific for NAD. A northern blot analysis revealed that transcription in P. stipitis is induced during growth onl-rhamnose but not on other carbon sources. [ABSTRACT FROM AUTHOR]

Abstract: The carcinogen and mutagen, 1-aminoanthracene, was efficiently metabolized by the fungal strain Beauveria bassiana ATCC 7159 to yield three new metabolites identified as 1-acetamido-5-[(4′-O-methyl-β-d-glucopyranosyl)oxy]anthracene, 1-acetamido-8-[(4′-O-methyl-β-d-glucopyranosyl)oxy]anthraquinone, and 1-acetamido-6-[(4′-O-methyl-β-d-glucopyranosyl)oxy]anthraquinone, together with 1-acetamidoanthracene and 1-acetamidoanthraquinone. Formation of these metabolites suggests that the metabolic pathways of 1-aminoanthracene in B. bassiana ATCC 7159 involve acetylation, oxidation, hydroxylation, and O-methylglucosylation. [Copyright &y& Elsevier]

Marine ectotherms, including oysters are exposed to variable environmental conditions in coastal shallow waters and estuaries. In the light of global climate change, additional stressors like pollution might pose higher risk to populations. On the basis of the concept of oxygen- and capacity-limited thermal tolerance in aquatic ectotherms (40), we show that a persistent pollutant, cadmium, can have detrimental effects on oysters (Crassostrea virginica). During acute warming from 20 to 28°C (4°C/48 h) standard metabolic rate (SMR) rose in control and cadmium-exposed (50 µ Cd2+/l) animals, with a consistently higher SMR in Cd-exposed oysters. Additionally, Cd-exposed oysters showed a stronger temperature-dependent decrease in hemolymph oxygen partial pressures. This observation indicates that the effect of temperature on aerobic metabolism was exacerbated due to the additional Cd stress. The oxygen delivery systems could not provide enough oxygen to cover Cd-induced elevated metabolic demands at high temperatures. Interestingly, cardiac performance (measured as the heart rate and hemolymph supply to tissues) rose to a similar extent in control and Cd-exposed oysters with warming indicating that cardiac output was unable to compensate for elevated energy demand in Cd-exposed oysters. Together with the literature data on metal-induced reduction of ventilatory capacity, these findings suggest that synergistic effects of elevated temperatures and cadmium exposure led to oxygen limitation by impaired performance in oxygen supply through ventilation and circulation. Overall, cadmium exposure resulted in progressive hypoxemia in oysters at high temperatures, suggesting that the thermal tolerance window is narrowed in marine ectotherms inhabiting polluted areas compared with pristine environments. [ABSTRACT FROM AUTHOR]

Abstract: Catalase (CAT; EC 1.11.1.6) isolated from leaves of the halophytic plant Mesembryanthemum crystallinum is characterized by a high apparent molecular mass of about 320kDa, and high resistance to denaturing agents (10% ME). SDS-treatment breaks active oligomeric CAT into the less active and putatively dimeric form of 160kDa apparent molecular mass. Three subunits are resolved after denaturing PAGE: 79, 74 and 62kDa. Higher molecular masses of subunits coincide with increased activity of CAT. M. crystallinum leaf CAT reveals a diel variation in the resistance to denaturing factors and the stability of CAT is increased in a light-dependent manner both in C3- and in CAM-induced plants. Unchanged level of leaf CAT transcripts is documented in the diurnal cycle of C3 plants and after salinity-induced crassulacean acid metabolism (CAM). [Copyright &y& Elsevier]

Critical O2 levels which induce modified atmosphere-related browning disorders in ‘Fuyu’ persimmon fruit were determined using controlled atmosphere (CA) storage at two different temperatures. Fruit were harvested at commercial maturity and stored for 4 months under different CA regimes and temperature. In the 2000–2001 season, O2 levels were adjusted to 0.5–0.75 or 0.1–0.3kPa in combination with 5.0–7.5 and 10.0–12.5kPaCO2, respectively, at 0°C. In the 2001–2002 season, two different O2 levels, 0.5 and 0.25kPa O2, were combined with 9.0kPa CO2 at −1.0 and 1.0°C. Incidence of the stylar-end-specific browning (SEB) disorder was almost 0 above the 0.50kPa O2 level regardless of CO2 concentration, whereas it was noticeable at 0.40–0.50kPa, indicating that inductive O2 levels for SEB are below 0.4kPa. Other types of browning such as pitted specks (PS) and pitted blotch browning (PBB) all over the surface occurred at 0.50kPa O2, and the incidence tended to increase at lower O2 levels. Effects of storage temperature on the incidence of browning disorders were not significant except that lower storage temperature enhanced post-storage development of flesh blotch browning. Incidence of SEB was closely related with internal ethanol content, while incidence of PBB did not show clear relationships with the ethanol contents. Tissue specificity of SEB seemed to be closely related to the accumulation of anaerobic metabolites in the stylar-end part of the fruit. [Copyright &y& Elsevier]