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Xylan is an important part of plant biomass and represents a renewable raw material for biorefineries. Contrary to cellulose, the structure of hemicellulose is quite complex. Therefore, the biodegradation of xylan needs the cooperation of many enzymes. For industrial production of xylanase multienzyme complexes (cocktails) and selected monocomponent xylanases, different Trichoderma reesei mutants and recombinants are used. T. reesei QM 6a (wild-type parent of best existing mutants) was selected as a starting material in the 1960s when the modern in-depth analytical methods were not yet in use. Therefore, screening of fungi genetically close to T. reesei in biodegradation of xylan may have a scientific value. Fifteen different strains from Trichoderma section Longibrachiatum have been tested for extracellular xylan-degrading enzyme production on three carbon sources (wheat straw, corn fiber, and eucalyptus wood) in shake flask cultivation. The enzyme activities were evaluated by traditional colorimetric enzyme assays and by HPLC and matrix assisted laser desorption/ionization time-of-flight mass spectrometry. Degradation of xylan was studied on four different xylan-rich model substrates. T. reesei CPK 155, Trichoderma parareesei TUB F-2535, and Trichoderma gracile TUB F-2543 isolates were equally good or better in degradation of the wheat arabinoxylan (WAX) and corn fiber alcohol insoluble solids as hydolysis substrates than the well-known T. reesei QM 6a and RUT C30 strains. Though Trichoderma saturnisporum ATCC 18903 gave relatively low volumetric enzyme activities by traditional colorimetric assays, it could release quite large amount of hydrolysis products (mono- and oligosaccharides) from WAX. Therefore, these fungi may be potential candidates for further experiments. Enzyme production on wheat straw and corn fiber carbon sources was more effective than on eucalyptus wood

In a paper published fifteen years ago, Gorman et al. (Nature 391, 479–481) made precise claims about how sensitive the African wild dog is to kleptoparasitism by spotted hyaenas Crocuta crocuta and lions Panthera leo. These claims are regularly referred to in the literature, and so far, they have remained unchallenged. However, careful perusal of their paper and analysis of the available data on energy intake and expenditure by wild dogs show that their claims are unfounded. Contrary to Gorman et al., wild dogs can usually take loss of food by kleptoparasitism in their stride. We present the calculations of the energy budget of wild dogs that remain implicit in the paper by Gorman et al.

Biodegradation rates of benzoate and related aromatic compounds, 3-nitrobenzoate, 4-chlorobenzoate, 4-chlorophenol, and 2,4-dichlorophenol by unexposed (unacclimated) and long-term exposed (acclimated) biomass were quantified using a modified fed-batch technique. The acclimated biomass was taken after approximately 1-year of operation from three lab-scale sequencing batch reactors (SBR). These reactors were operated under various cycling electron acceptor conditions with a continuous feed of a synthetic wastewater containing biogenic and nonbiogenic chemicals including benzoate, 3-nitrobenzoate, and 4-chlorophenol, but not 4-chlorobenzoate or 2,4-dichlorophenol. The unexposed biomass was taken from a full-scale wastewater treatment plant, which constituted one of the original sources of inoculum for the lab-scale SBRs. The acclimated biomass manifested high removal rates of benzoate and related aromatic compounds with additional removal of structurally similar chemicals (4-chlorobenzoate and 2,4-dichlorophenol). The unacclimated biomass showed no removal of 3-nitrobenzoate, 4-chlorobenzoate or 2,4-dichlorophenol. Addition of biogenic substrates reduced the degradation of most aromatic compounds tested, but it enhanced 2,4-dichlorophenol removal. Biodegradation rates of each aromatic compound with the biomass from the anoxic/aerobic SBR were further determined under anaerobic (absence of aeration and NO3-), anoxic (no aeration, but with surplus NO3-), standard oxygen (DO > 0.2 mg/L), and elevated oxygen (DO > 25 mg/L) conditions. The removal rate of both benzoate and 3-nitrobenzoate decreased under anaerobic condition but not under the anoxic condition; 4-chlorophenol biodegradation, on the other hand, was reduced significantly under both anoxic and anaerobic conditions. The removal rates of aromatic compounds, particularly those of 3-nitrobenzoate and 2,4-dichlorophenol, increased significantly under elevated dissolved oxygen conditions. Our results demonstrated that when the biochemical conditions shifted from oxygen-respiration to nitrate respiration, to anaerobiosis, the biodegradation rates of test aromatic compounds decreased or ceased.

The heavy metal thallium is an emerging pollutant among the most potentially toxic species to which human populations are exposed. Its harmful effects on living organisms are well-known at high doses, typical of acute intoxication. Its harmful effects at low doses are by far less known. In a previous paper, we reported a TlCl-induced metabolic shift to lactate and ethanol production in living hippocampal HN9.10e neurons that appeared after a single short exposure (48 h) at low doses (1-100 μg/L). This metabolic shift to lactate and ethanol suggests a marked impairment of cell bioenergetics. In this work, we provide detailed evidence for TlCl-induced changes of neuronal morphology and mitochondrial activity. Confocal microscopy and fluorescent probes were used to qualitatively and quantitatively analyze, at the subcellular level, living HN9.10e neurons during and after TlCl exposure. An early onset mitochondrial dysfunction appeared, associated with signs of cellular deregulation such as neurite shortening, loss of substrate adhesion, and increase of cytoplasmic calcium. The dose-dependent alteration of mitochondrial ROS (mtROS) level and of transmembrane mitochondrial potential (ΔΨm) has been observed also for very low TlCl doses (1 μg/L). The treatment with the ATP synthase inhibitor oligomycin revealed a severe impairment of the mitochondrial function, more significant than that measured by the simple quantification of the tetramethylrhodamine methyl ester (TMRM) fluorescence. These results highlight that mitochondria are a key subcellular target of TlCl neurotoxicity. The transmembrane mitochondrial potential was significantly correlated with the ethanol concentration in cell culture medium ( P < 0.001, r = -0.817), suggesting that ethanol could be potentially used as a biomarker of mitochondrial impairment.

AbstractThe possible effects on cognitive processes of external electric fields, such as those generated by power line pillars and household appliances are of increasing public concern. They are difficult to study experimentally, and the relatively scarce and contradictory evidence make it difficult to clearly assess these effects. In this study, we investigate how, why and to what extent external perturbations of the intrinsic neuronal activity, such as those that can be caused by generation, transmission and use of electrical energy can affect neuronal activity during cognitive processes. For this purpose, we used a morphologically and biophysically realistic three‐dimensional model of CA1 pyramidal neurons. The simulation findings suggest that an electric field oscillating at power lines frequency, and environmentally measured strength, can significantly alter both the average firing rate and temporal spike distribution properties of a hippocampal CA1 pyramidal neuron. This effect strongly depends on the specific and instantaneous relative spatial location of the neuron with respect to the field, and on the synaptic input properties. The model makes experimentally testable predictions on the possible functional consequences for normal hippocampal functions such as object recognition and spatial navigation. The results suggest that, although EF effects on cognitive processes may be difficult to occur in everyday life, their functional consequences deserve some consideration, especially when they constitute a systematic presence in living environments.

Lysozyme-induced fusion of phosphatidylserine (PS) vesicles was studied as a function of pH. Fusion, monitored by lipid-mixing, was measured by following the dilution of pyrene-labelled phosphatidylcholine, incorporated in PS vesicles, into unlabelled bilayers. It is demonstrated that lysozyme-induced fusion is pH-dependent and significant fusion is triggered at pH 5 or below. The interaction of lysozyme with the vesicle bilayer was characterized by measuring resonance energy transfer from tryptophane, present in the protein, to pyrene. It is shown that concomitant with fusion, a strong resonance energy transfer signal appears at pH 5 or below. Furthermore, in monolayer experiments it was found that addition of lysozyme to the subphase caused an increase in surface pressure, when the pH was kept below 5.5. Very low concentrations of lysozyme sufficed to bring about the observed effects. The results are taken to indicate that lysozyme-induced fusion results from penetration of protein into the hydrophobic core of the bilayer, occurring at acidic pH.

The biotransformation of lignocellulose biomasses into fermentable sugars is a very complex procedure including, as one of the most critical steps, the (hemi) cellulose hydrolysis by specific enzymatic cocktails. We explored here, the potential of stable glycoside hydrolases from thermophilic organisms, so far not used in commercial enzymatic preparations, for the conversion of glucuronoxylan, the major hemicellulose of several energy crops. Searches in the genomes of thermophilic bacteria led to the identification, efficient production, and detailed characterization of novel xylanase and α-glucuronidase from Alicyclobacillus acidocaldarius (GH10-XA and GH67-GA, respectively) and a α-glucuronidase from Caldicellulosiruptor saccharolyticus (GH67-GC). Remarkably, GH10-XA, if compared to other thermophilic xylanases from this family, coupled good specificity on beechwood xylan and the best stability at 65 °C (3.5 days). In addition, GH67-GC was the most stable α-glucuronidases from this family and the first able to hydrolyse both aldouronic acid and aryl-α-glucuronic acid substrates. These enzymes, led to the very efficient hydrolysis of beechwood xylan by using 7- to 9-fold less protein (concentrations <0.3 μM) and in much less reaction time (2h vs 12h) if compared to other known biotransformations catalyzed by thermophilic enzymes. In addition, remarkably, together with a thermophilic β-xylosidase, they catalyzed the production of xylose from the smart cooking pre-treated biomass of one of the most promising energy crops for second generation biorefineries. We demonstrated that search by the CAZy Data Bank of currently available genomes and detailed enzymatic characterization of recombinant enzymes allow the identification of glycoside hydrolases with novel and interesting properties and applications.

Excessive alcohol intake frequently results in gastrointestinal discomfort. It is an empirical fact that the severity of gastrointestinal discomfort induced by alcohol abuse is subject to interindividual variation. The aim of this study was to determine whether genetic polymorphism in alcohol dehydrogenase 3 (ADH3) and cytochrome P450 2E1 (CYP2E1), important first-pass enzymes in the metabolism of ethanol, predispose to the development of gastrointestinal symptoms in alcoholics, Blood samples were obtained from 92 adult alcoholics admitted for detoxification. The samples were analyzed for genetic polymorphism in ADH3 and CYP2E1 by polymerase chain reaction followed by restriction fragment length polymorphism analyses. During an interview on the first day of hospital admission, patient characteristics and gastrointestinal symptoms in the week before admission were assessed. A total of 75 of 92 alcoholics (83%) reported symptoms: 66 patients had upper gastrointestinal symptoms (72%), 70 patients had lower gastrointestinal symptoms (76%), and 59 patients reported alarming symptoms (64%). Patients with gastrointestinal symptoms less often abused beer in comparison to those without gastrointestinal symptoms (P = 0.05). The numbers of patients with the homozygous y1y1 genotype, the heterozygous y1y2 genotype, and the homozygous y2y2 genotype in ADH3 who reported gastrointestinal symptoms were 20 (83%), 34 (76%), and 15 (88%), respectively. The number of patients with the heterozygous c1c2 CYP2E1 genotype (5%) and the heterozygous DC CYP2E1 genotype (14%) was low and also unrelated to gastrointestinal symptoms. Our data suggest that the ethanol concentrations of the consumed beverages, and not interindividual variations in the activities of first-pass alcohol-metabolizing enzymes, are associated with gastrointestinal symptoms in alcoholics.