Simultaneous hydrogen utilization and in situ biogas upgrading in an anaerobic reactor

The possibility of converting hydrogen to methane and simultaneous upgrading of biogas was investigated in both batch tests and fully mixed biogas reactor, simultaneously fed with manure and hydrogen. Batch experiments showed that hydrogen could be converted to methane by hydrogenotrophic methanogenesis with conversion of more than 90% of the consumed hydrogen to methane. The hydrogen consumption rates were affected by both (hydrogen partial pressure) and mixing intensity. Inhibition of propionate and butyrate degradation by hydrogen (1 atm) was only observed under high mixing intensity (shaking speed 300 rpm). Continuous addition of hydrogen (flow rate of 28.6 mL/(L/h)) to an anaerobic reactor fed with manure, showed that more than 80% of the hydrogen was utilized. The propionate and butyrate level in the reactor was not significantly affected by the hydrogen addition. The methane production rate of the reactor with H₂ addition was 22% higher, compared to the control reactor only fed with manure. The CO₂ content in the produced biogas was only 15%, while it was 38% in the control reactor. However, the addition of hydrogen resulted in increase of pH (from 8.0 to 8.3) due to the consumption of bicarbonate, which subsequently caused slight inhibition of methanogenesis. Biotechnol. Bioeng. 2012; 109:1088–1094. © 2011 Wiley Periodicals, Inc.     

Effects of pH and hydraulic retention time on hydrogen production versus methanogenesis during anaerobic fermentation of organic household solid waste under extreme-thermophilic temperature (70 degrees C)

Two continuously stirred tank reactors were operated with household solid waste at 70 degrees C, for hydrogen and methane production. The individual effect of hydraulic retention time (HRT as 1, 2, 3, 4, and 6 days) at pH 7 or pH (5, 5.5, 6, 6.5, 7) at 3-day HRT was investigated on the hydrogen production versus methanogenesis. It was found that at pH 7, the maximum hydrogen yield was 107 mL-H(2)/g VS(added) (volatile solid added) but no stable hydrogen production was obtained as after some time methanogenesis was initiated at all tested HRTs. This demonstrated that sludge retention time alone was not enough for washing out the methanogens at pH 7 under extreme-thermophilic conditions. Oppositely, we showed that keeping the pH level at 5.5 was enough to inhibit methane and produce hydrogen stably at 3-day HRT. However, the maximum stable hydrogen yield was low at 21 mL-H(2)/g VS(added).     

The common gamma-chain cytokines IL-2, IL-7, IL-15, and IL-21 induce the expression of programmed death-1 and its ligands

The programmed death (PD)-1 molecule and its ligands (PD-L1 and PD-L2), negative regulatory members of the B7 family, play an important role in peripheral tolerance. Previous studies have demonstrated that PD-1 is up-regulated on T cells following TCR-mediated activation; however, little is known regarding PD-1 and Ag-independent, cytokine-induced T cell activation. The common gamma-chain (gamma c) cytokines IL-2, IL-7, IL-15, and IL-21, which play an important role in peripheral T cell expansion and survival, were found to up-regulate PD-1 and, with the exception of IL-21, PD-L1 on purified T cells in vitro. This effect was most prominent on memory T cells. Furthermore, these cytokines induced, indirectly, the expression of PD-L1 and PD-L2 on monocytes/macrophages in PBMC. The in vivo correlate of these observations was confirmed on PBMC isolated from HIV-infected individuals receiving IL-2 immunotherapy. Exposure of gamma c cytokine pretreated T cells to PD-1 ligand-IgG had no effect on STAT5 activation, T cell proliferation, or survival driven by gamma c cytokines. However, PD-1 ligand-IgG dramatically inhibited anti-CD3/CD28-driven proliferation and Lck activation. Furthermore, following restimulation with anti-CD3/CD28, cytokine secretion by both gamma c cytokine and anti-CD3/CD28 pretreated T cells was suppressed. These data suggest that gamma c cytokine-induced PD-1 does not interfere with cytokine-driven peripheral T cell expansion/survival, but may act to suppress certain effector functions of cytokine-stimulated cells upon TCR engagement, thereby minimizing immune-mediated damage to the host.     

Isocyanide-based multicomponent reactions in drug discovery

This review describes recent advances in the application of isocyanide-based multicomponent reactions (IMCRs) in drug discovery and summarizes the various chemotypes used to probe biological targets. In the past couple of years, IMCR-derived ligands have been used to develop agents against infectious diseases and to interfere with protein-protein interactions. Additionally, they were active against a variety of targets such as enzymes, GPCRs and ion channels. The rational for the chemical biologist to apply such diversity generating chemistries is also discussed.     

Configuration of heptopyranoside and heptofuranoside side chains: 2-anthroate,a powerful chromophore for exciton coupled CD

The absolute configuration of the acyclic side chain of heptopyranosides and heptofuranosides was determined by exciton coupled CD, employing the strongly fluorescent 2-anthroate chromophore. The usage of this chromophore offers significant improvements over previous chemical and spectroscopic procedures since its intense fluorescence greatly facilitates the isolation and HPLC purification at the nanogram scale. The large amplitudes of the bisignate spectra allow CD manipulations in the 1 × 10⁻⁷ M range. Chirality 9:699–712, 1997. © 1997 Wiley-Liss, Inc.     

Novel hits for acetylcholinesterase inhibition derived by docking-based screening on ZINC database

The inhibition of the enzyme acetylcholinesterase (AChE) increases the levels of the neurotransmitter acetylcholine and symptomatically improves the affected cognitive function. In the present study, we searched for novel AChE inhibitors by docking-based virtual screening of the standard lead-like set of ZINC database containing more than 6 million small molecules using GOLD software. The top 10 best-scored hits were tested in vitro for AChE affinity, neurotoxicity, GIT and BBB permeability. The main pharmacokinetic parameters like volume of distribution, free fraction in plasma, total clearance, and half-life were predicted by previously derived models. Nine of the compounds bind to the enzyme with affinities from 0.517 to 0.735?µM, eight of them are non-toxic. All hits permeate GIT and BBB and bind extensively to plasma proteins. Most of them are low-clearance compounds. In total, seven of the 10 hits are promising for further lead optimisation. These are structures with ZINC IDs: 00220177, 44455618, 66142300, 71804814, 72065926, 96007907, and 97159977.     

Active transport of chloride by Anacystis nidulans

Chloride uptake by the cyanobacterium Anacystis nidulans at 38°C is energy dependent showing maximum rate (around 5.10^-7 mol Cl^-xml cell water^-1xmin^-1) and accumulation (up to 160 fold) in light and air. The respective values in air and darkness were 40–70% lower. In the dark under N₂ no uptake was found. Chloride transport had an optimum at pH 6.7 and a K _M of 2.10^-5 M which was pH-independent. It was inhibited by carbonyl cyanide m-chlorophenylhydrazone and N,N′-dicyclohexylcarbodiimide in the light and in the dark, and also to a lesser extent by valinomycin. 3-(3,4-dichlorophenyl)-1,1-dimethylurea in the light caused a moderate stimulation. To obtain information about the energy source of active chloride transport the action of the four inhibitors on membrane potential (determined through the distribution of triphenylmethylphosphonium) and ATP level (determined by the firefly method) was examined. It was found that a high negative membrane potential was unfavorable for chloride accumulation probably by stimulating passive efflux. On the other hand a good correlation between ATP level and chloride transport activity was obtained. Attempts to induce chloride uptake by sudden acidification of the external medium in presence of N,N′-dicyclohexyl-carbodiimide or during anaerobiosis were not successful. Two mechanisms of chloride uptake are discussed:

1. primary active transport by an ATP-dependent pump, and
2. “chemiosmotic” secondary active transport linked to a proton gradient, the present data favoring mechanism a.

     

Deletion of the Fission Yeast Homologue of Human Insulinase Reveals a TORC1-Dependent Pathway Mediating Resistance to Proteotoxic Stress

Insulin Degrading Enzyme (IDE) is a protease conserved through evolution with a role in diabetes and Alzheimer''s disease. The reason underlying its ubiquitous expression including cells lacking identified IDE substrates remains unknown. Here we show that the fission yeast IDE homologue (Iph1) modulates cellular sensitivity to endoplasmic reticulum (ER) stress in a manner dependent on TORC1 (Target of Rapamycin Complex 1). Reduced sensitivity to tunicamycin was associated with a smaller number of cells undergoing apoptosis. Wild type levels of tunicamycin sensitivity were restored in iph1 null cells when the TORC1 complex was inhibited by rapamycin or by heat inactivation of the Tor2 kinase. Although Iph1 cleaved hallmark IDE substrates including insulin efficiently, its role in the ER stress response was independent of its catalytic activity since expression of inactive Iph1 restored normal sensitivity. Importantly, wild type as well as inactive human IDE complemented gene-invalidated yeast cells when expressed at the genomic locus under the control of iph1⁺ promoter. These results suggest that IDE has a previously unknown function unrelated to substrate cleavage, which links sensitivity to ER stress to a pro-survival role of the TORC1 pathway.     

Evaluation of the Growth of Salmonellae in Rappaport's Broth and in Muller-Kauffmann's Tetrathionate Broth

S ummary . The behaviour of 70 strains of salmonellae belonging to 44 serotypes in Rappaport's broth and in Muller-Kauffmann's tetrathionate broth was examined. With an inoculum of 5–25 cells, 5 strains did not grow in Rappaport's medium, 2 multiplied slowly and 63 grew strongly in 24 h. With an inoculum of 100–500 organisms all but one strain grew readily in 24 h. In Muller–Kauffmann's tetrathionate broth inoculated with pure cultures of salmonellae, growth of many strains was markedly inhibited, in the absence of added faeces, at 37° and 43°. This inhibition was more severe with light inocula at 43°. The addition of 0.05% (w/v) of salmonella-free human faeces to Muller–Kauffmann's tetrathionate broth, did not stimulate growth of salmonellae. In contrast, the addition of 5% (w/v) of human stools to this medium resulted in a heavy growth of the added salmonellae, especially at 43°.     

Summer Squash Identification by High-Resolution-Melting (HRM) Analysis Using Gene-Based EST–SSR Molecular Markers

Cucurbita pepo (squash, pumpkin, gourd), a worldwide cultivated vegetable of American origin, is extremely variable in fruit characteristics. Most of its widely grown commercial types are known as summer squashes and belong to the elongated forms of C. pepo ssp. pepo (Cocozelle, Vegetable marrow and Zucchini groups). Here, we have integrated the high-resolution-melting (HRM) analysis method with expressed sequence tags–simple sequence repeat (EST–SSR) marker genotyping, in order to facilitate the identification of 36 summer squash landraces originated from Greece. The six EST–SSR loci used were informative and generated a unique melting curve profile of EST-derived microsatellites for each accession allowing their comparison and classification. Moreover, HRM was highly informative, as by using only four microsatellite markers we were able to discriminate 36 summer squash landraces and by using six EST–SSRs. We were able to construct a highly informative and discriminative dendrogram where the 36 genotypes were classified in six distinct clusters. Furthermore, we acquired information about the genes containing the EST–SSRs using bioinformatics tools. We found that the EST–SSRs used in this study were hybridizing to genes involved in stress response to heavy metals and biotic stresses or the production of flavonoids or symporters of important nitrogen sources, like xanthine and uric acid amongst others. The results presented here suggest that the panel of EST–SSR markers used in combination with HRM analysis could be useful in a variety of applications, like squash biodiversity assessment but most importantly in managing squash germplasm to improve breeding programs.