In vitro processing of the RNA-2-encoded polyprotein of two nepoviruses: tomato black ring virus and grapevine chrome mosaic virus.

Science.gov (United States)

Demangeat, G; Hemmer, O; Fritsch, C; Le Gall, O; Candresse, T

1991-02-01

In vitro translation of RNA-2 of each of two closely related nepoviruses, tomato black ring virus (TBRV) and grapevine chrome mosaic virus (GCMV), in a rabbit reticulocyte lysate resulted in the synthesis of single polypeptides of 150K and 146K respectively. Processing of these polyproteins occurred after the addition of translation products of homologous RNA-1. The positions of the cleavage products within the polyproteins were determined. From the N to the C terminus, Mr values for the proteins were 50K, 46K and 59K for TBRV and 44K, 46K and 56K for GCMV. TBRV RNA-1 translation products also cleaved the polyproteins encoded by GCMV RNA-2 which suggests that the cleavage sites in the two polyproteins are similar.

Intermolecular cleavage by UmuD-like mutagenesis proteins

Science.gov (United States)

McDonald, John P.; Frank, Ekaterina G.; Levine, Arthur S.; Woodgate, Roger

1998-01-01

The activity of a number of proteins is regulated by self-processing reactions. Elegant examples are the cleavage of the prokaryotic LexA and λCI transcriptional repressors and the UmuD-like mutagenesis proteins. Various studies support the hypothesis that LexA and λCI cleavage reactions are predominantly intramolecular in nature. The recently described crystal structure of the Escherichia coli UmuD′ protein (the posttranslational cleavage product of the UmuD protein) suggests, however, that the region of the protein corresponding to the cleavage site is at least 50 Å away from the catalytic active site. We considered the possibility, therefore, that the UmuD-like proteins might undergo self-processing that, in contrast to LexA and λCI, occurs via an intermolecular rather than intramolecular reaction. To test this hypothesis, we introduced into E. coli compatible plasmids with mutations at either the cleavage or the catalytic site of three UmuD-like proteins. Cleavage of these proteins only occurs in the presence of both plasmids, indicating that the reaction is indeed intermolecular in nature. Furthermore, this intermolecular reaction is completely dependent upon the multifunctional RecA protein and leads to the restoration of cellular mutagenesis in nonmutable E. coli strains. Intermolecular cleavage of a biotinylated UmuD active site mutant was also observed in vitro in the presence of the wild-type UmuD′ protein, indicating that in addition to the intact UmuD protein, the normal cleavage product (UmuD′) can also act as a classical enzyme. PMID:9465040

Synthesis and DNA cleavage activity of Bis-3-chloropiperidines as alkylating agents.

Science.gov (United States)

Zuravka, Ivonne; Roesmann, Rolf; Sosic, Alice; Wende, Wolfgang; Pingoud, Alfred; Gatto, Barbara; Göttlich, Richard

2014-09-01

Nitrogen mustards are an important class of bifunctional alkylating agents routinely used in chemotherapy. They react with DNA as electrophiles through the formation of highly reactive aziridinium ion intermediates. The antibiotic 593A, with potential antitumor activity, can be considered a naturally occurring piperidine mustard containing a unique 3-chloropiperidine ring. However, the total synthesis of this antibiotic proved to be rather challenging. With the aim of designing simplified analogues of this natural product, we developed an efficient bidirectional synthetic route to bis-3-chloropiperidines joined by flexible, conformationally restricted, or rigid diamine linkers. The key step involves an iodide-catalyzed double cyclization of unsaturated bis-N-chloroamines to simultaneously generate both piperidine rings. Herein we describe the synthesis and subsequent evaluation of a series of novel nitrogen-bridged bis-3-chloropiperidines, enabling the study of the impact of the linker structure on DNA alkylation properties. Our studies reveal that the synthesized compounds possess DNA alkylating abilities and induce strand cleavage, with a strong preference for guanine residues. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inferring biome-scale net primary productivity from tree-ring isotopes

Science.gov (United States)

Pederson, N.; Levesque, M.; Williams, A. P.; Hobi, M. L.; Smith, W. K.; Andreu-Hayles, L.

2017-12-01

Satellite estimates of vegetation growth (net primary productivity; NPP), tree-ring records, and forest inventories indicate that ongoing climate change and rising atmospheric CO2 concentration are altering productivity and carbon storage of forests worldwide. The impact of global change on the trends of NPP, however, remain unknown because of the lack of long-term high-resolution NPP data. For the first time, we tested if annually resolved carbon (δ13C) and oxygen (δ18O) stable isotopes from the cellulose of tree rings from trees in temperate regions could be used as a tool for inferring NPP across spatiotemporal scales. We compared satellite NPP estimates from the moderate-resolution imaging spectroradiometer sensor (MODIS, product MOD17A) and a newly developed global NPP dataset derived from the Global Inventory Modeling and Mapping Studies (GIMMS) dataset to annually resolved tree-ring width and δ13C and δ18O records from four sites along a hydroclimatic gradient in Eastern and Central United States. We found strong correlations across large geographical regions between satellite-derived NPP and tree-ring isotopes that ranged from -0.40 to -0.91. Notably, tree-ring derived δ18O had the strongest relation to climate. The results were consistent among the studied tree species (Quercus rubra and Liriodendron tulipifera) and along the hydroclimatic conditions of our network. Our study indicates that tree-ring isotopes can potentially be used to reconstruct NPP in time and space. As such, our findings represent an important breakthrough for estimating long-term changes in vegetation productivity at the biome scale.

Pripper: prediction of caspase cleavage sites from whole proteomes

Directory of Open Access Journals (Sweden)

Salmi Jussi

2010-06-01

Full Text Available Abstract Background Caspases are a family of proteases that have central functions in programmed cell death (apoptosis and inflammation. Caspases mediate their effects through aspartate-specific cleavage of their target proteins, and at present almost 400 caspase substrates are known. There are several methods developed to predict caspase cleavage sites from individual proteins, but currently none of them can be used to predict caspase cleavage sites from multiple proteins or entire proteomes, or to use several classifiers in combination. The possibility to create a database from predicted caspase cleavage products for the whole genome could significantly aid in identifying novel caspase targets from tandem mass spectrometry based proteomic experiments. Results Three different pattern recognition classifiers were developed for predicting caspase cleavage sites from protein sequences. Evaluation of the classifiers with quality measures indicated that all of the three classifiers performed well in predicting caspase cleavage sites, and when combining different classifiers the accuracy increased further. A new tool, Pripper, was developed to utilize the classifiers and predict the caspase cut sites from an arbitrary number of input sequences. A database was constructed with the developed tool, and it was used to identify caspase target proteins from tandem mass spectrometry data from two different proteomic experiments. Both known caspase cleavage products as well as novel cleavage products were identified using the database demonstrating the usefulness of the tool. Pripper is not restricted to predicting only caspase cut sites, but it gives the possibility to scan protein sequences for any given motif(s and predict cut sites once a suitable cut site prediction model for any other protease has been developed. Pripper is freely available and can be downloaded from http://users.utu.fi/mijopi/Pripper. Conclusions We have developed Pripper, a tool for

Blocking Internalization of Phosphatidylethanolamine at Cleavage Furrow of Mitosis as a Novel Mechanism of Anti-Breast Cancer Strategy

National Research Council Canada - National Science Library

Cui, Zhen

2002-01-01

During the formation of cleavage furrow of mitosis, phosphatidylethanolamine (PE) flips from inner leaflet of the plasma membrane to the outer leaflet specifically in the furrow region near the contractile ring...

Blocking Internalization of Phosphatidylethanolamine at Cleavage Furrow of Mitosis as a Novel Mechanism of Anti-Breast-Cancer Strategy

National Research Council Canada - National Science Library

Cui, Zheng

2003-01-01

During the formation of cleavage furrow of mitosis, phosphatidylethanolamine (PE) flips from inner leaflet of the plasma membrane to the outer leaflet specifically in the furrow region near the contractile ring...

[Comparative study of aromatic ring meta-cleavage enzymes in Pseudomonas strains with plasmid and chromosomal genetic control of the catabolism of biphenyl and m-toluate].

Science.gov (United States)

Selifonov, S A; Starozoĭtov, I I

1990-12-01

It was shown that two different enzymes of aromatic ring oxidative meta-cleavage (2,3-dihydroxybiphenyl-1,2-dioxygenase), DBO and catechol-2,3-dioxygenase, C230) function in Pseudomonas strains with a plasmid and chromosomal genetic control of biphenyl and toluate catabolism. A comparative analysis of DBO's and C230's expressed by the pBS241 biphenyl degradative plasmid in P. putida BS893, pBS311 in P. putida U83, chromosomal genes in P. putida BF and C230 from P. putida PaW160 (pWWO) was carried out. It was found that the DBO's of all strains under study are highly specialized enzymes in respect of 2,3-dihydroxybiphenyl cleavage and are also able to cleave 3-methyl-catechol and catechol (but not 4-methylcatechol) at low rates. In contrast with DBO's, in Pseudomonas strains the substrate specificities of all C230's are variable. The C230's expressed by the D-plasmids pBS241 and pBC311 have a moderate affinity for catechol, 3-methyl- and 4-methylcatechol, but are unable to cleave 2,3-dihydroxybiphenyl. The C230 which is encoded by the chromosomal structure gene from P. putida BF is very similar to C230 which codes for the TOL-plasmid pWWO. These plasmid differ from C230's expressed by biphenyl D-plasmids due to their capability to cleave 2,3-dihydroxybiphenyl in addition to catechol cleavage. All DBO's and C230's under study possess a number of properties that are typical for the enzymes having an oxidative meta-cleaving effect. The different roles of these enzymes in biphenyl and toluate catabolism in Pseudomonas strains are discussed.

Oxidation of Benzene by Persulfate in the Presence of Fe(III)- and Mn(IV)-Containing Oxides: Stoichiometric Efficiency and Transformation Products.

Science.gov (United States)

Liu, Haizhou; Bruton, Thomas A; Li, Wei; Buren, Jean Van; Prasse, Carsten; Doyle, Fiona M; Sedlak, David L

2016-01-19

Sulfate radical (SO4(•-)) is a strong, short-lived oxidant that is produced when persulfate (S2O8(2-)) reacts with transition metal oxides during in situ chemical oxidation (ISCO) of contaminated groundwater. Although engineers are aware of the ability of transition metal oxides to activate persulfate, the operation of ISCO remediation systems is hampered by an inadequate understanding of the factors that control SO4(•-) production and the overall efficiency of the process. To address these shortcomings, we assessed the stoichiometric efficiency and products of transition metal-catalyzed persulfate oxidation of benzene with pure iron- and manganese-containing minerals, clays, and aquifer solids. For most metal-containing solids, the stoichiometric efficiency, as determined by the loss of benzene relative to the loss of persulfate, approached the theoretical maximum. Rates of production of SO4(•-) or hydroxyl radical (HO(•)) generated from radical chain reactions were affected by the concentration of benzene, with rates of S2O8(2-) decomposition increasing as the benzene concentration increased. Under conditions selected to minimize the loss of initial transformation products through reaction with radicals, the production of phenol only accounted for 30%-60% of the benzene lost in the presence of O2. The remaining products included a ring-cleavage product that appeared to contain an α,β-unsaturated aldehyde functional group. In the absence of O2, the concentration of the ring-cleavage product increased relative to phenol. The formation of the ring-cleavage product warrants further studies of its toxicity and persistence in the subsurface.

SKI2 mediates degradation of RISC 5'-cleavage fragments and prevents secondary siRNA production from miRNA targets in Arabidopsis.

Science.gov (United States)

Branscheid, Anja; Marchais, Antonin; Schott, Gregory; Lange, Heike; Gagliardi, Dominique; Andersen, Stig Uggerhøj; Voinnet, Olivier; Brodersen, Peter

2015-12-15

Small regulatory RNAs are fundamental in eukaryotic and prokaryotic gene regulation. In plants, an important element of post-transcriptional control is effected by 20-24 nt microRNAs (miRNAs) and short interfering RNAs (siRNAs) bound to the ARGONAUTE1 (AGO1) protein in an RNA induced silencing complex (RISC). AGO1 may cleave target mRNAs with small RNA complementarity, but the fate of the resulting cleavage fragments remains incompletely understood. Here, we show that SKI2, SKI3 and SKI8, subunits of a cytoplasmic cofactor of the RNA exosome, are required for degradation of RISC 5', but not 3'-cleavage fragments in Arabidopsis. In the absence of SKI2 activity, many miRNA targets produce siRNAs via the RNA-dependent RNA polymerase 6 (RDR6) pathway. These siRNAs are low-abundant, and map close to the cleavage site. In most cases, siRNAs were produced 5' to the cleavage site, but several examples of 3'-spreading were also identified. These observations suggest that siRNAs do not simply derive from RDR6 action on stable 5'-cleavage fragments and hence that SKI2 has a direct role in limiting secondary siRNA production in addition to its function in mediating degradation of 5'-cleavage fragments. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Kininogen Cleavage Assay: Diagnostic Assistance for Kinin-Mediated Angioedema Conditions.

Directory of Open Access Journals (Sweden)

Rémi Baroso

Full Text Available Angioedema without wheals (AE is a symptom characterised by localised episodes of oedema presumably caused by kinin release from kininogen cleavage. It can result from a hereditary deficiency in C1 Inhibitor (C1Inh, but it can present with normal level of C1Inh. These forms are typically difficult to diagnose although enhanced kinin production is suspected or demonstrated in some cases.We wanted to investigate bradykinin overproduction in all AE condition with normal C1Inh, excluding cases with enhanced kinin catabolism, and to propose this parameter as a disease biomarker.We retrospectively investigated high molecular weight kininogen (HK cleavage pattern, using gel electrophoresis and immunorevelation. Plasma samples were drawn using the same standardised procedure from blood donors or AE patients with normal C1Inh conditions, normal kinin catabolism, and without prophylaxis.Circulating native HK plasma concentrations were similar in the healthy men (interquartile range: 98-175μg/mL, n = 51 and in healthy women (90-176μg/mL, n = 74, while HK cleavage was lower (p14.4% HK cleavage for men; 33.0% HK cleavage for women, with >98% specificity achieved for all parameters. In plasma from patients undergoing recovery two months after oestrogen/progestin combination withdrawal (n = 13 or two weeks after AE attack (n = 2, HK cleavage was not fully restored, suggesting its use as a post-attack assay.As a diagnostic tool, HK cleavage can offer physicians supportive arguments for kinin production in suspected AE cases and improve patient follow-up in clinical trials or prophylactic management.

New Insight into the Cleavage Reaction of Nostoc sp. Strain PCC 7120 Carotenoid Cleavage Dioxygenase in Natural and Nonnatural Carotenoids

Science.gov (United States)

Heo, Jinsol; Kim, Se Hyeuk

2013-01-01

Carotenoid cleavage dioxygenases (CCDs) are enzymes that catalyze the oxidative cleavage of carotenoids at a specific double bond to generate apocarotenoids. In this study, we investigated the activity and substrate preferences of NSC3, a CCD of Nostoc sp. strain PCC 7120, in vivo and in vitro using natural and nonnatural carotenoid structures. NSC3 cleaved β-apo-8′-carotenal at 3 positions, C-13C-14, C-15C-15′, and C-13′C-14′, revealing a unique cleavage pattern. NSC3 cleaves the natural structure of carotenoids 4,4′-diaponeurosporene, 4,4′-diaponeurosporen-4′-al, 4,4′-diaponeurosporen-4′-oic acid, 4,4′-diapotorulene, and 4,4′-diapotorulen-4′-al to generate novel cleavage products (apo-14′-diaponeurosporenal, apo-13′-diaponeurosporenal, apo-10′-diaponeurosporenal, apo-14′-diapotorulenal, and apo-10′-diapotorulenal, respectively). The study of carotenoids with natural or nonnatural structures produced by using synthetic modules could provide information valuable for understanding the cleavage reactions or substrate preferences of other CCDs in vivo and in vitro. PMID:23524669

Cleavage of nicotinamide adenine dinucleotide by the ribosome-inactivating protein from Momordica charantia.

Science.gov (United States)

Vinkovic, M; Dunn, G; Wood, G E; Husain, J; Wood, S P; Gill, R

2015-09-01

The interaction of momordin, a type 1 ribosome-inactivating protein from Momordica charantia, with NADP(+) and NADPH has been investigated by X-ray diffraction analysis of complexes generated by co-crystallization and crystal soaking. It is known that the proteins of this family readily cleave the adenine-ribose bond of adenosine and related nucleotides in the crystal, leaving the product, adenine, bound to the enzyme active site. Surprisingly, the nicotinamide-ribose bond of oxidized NADP(+) is cleaved, leaving nicotinamide bound in the active site in the same position but in a slightly different orientation to that of the five-membered ring of adenine. No binding or cleavage of NADPH was observed at pH 7.4 in these experiments. These observations are in accord with current views of the enzyme mechanism and may contribute to ongoing searches for effective inhibitors.

Novel carotenoid cleavage dioxygenase catalyzes the first dedicated step in saffron crocin biosynthesis

KAUST Repository

Frusciante, Sarah; Diretto, Gianfranco; Bruno, Mark; Ferrante, Paola; Pietrella, Marco; Prado-Cabrero, Alfonso; Rubio-Moraga, Á ngela L.; Beyer, Peter D.; Gó mez-Gó mez, Lourdes; Al-Babili, Salim; Giuliano, Giovanni

2014-01-01

Crocus sativus stigmas are the source of the saffron spice and accumulate the apocarotenoids crocetin, crocins, picrocrocin, and safranal, responsible for its color, taste, and aroma. Through deep transcriptome sequencing, we identified a novel dioxygenase, carotenoid cleavage dioxygenase 2 (CCD2), expressed early during stigma development and closely related to, but distinct from, the CCD1 dioxygenase family. CCD2 is the only identified member of a novel CCD clade, presents the structural features of a bona fide CCD, and is able to cleave zeaxanthin, the presumed precursor of saffron apocarotenoids, both in Escherichia coli and in maize endosperm. The cleavage products, identified through high-resolution mass spectrometry and comigration with authentic standards, are crocetin dialdehyde and crocetin, respectively. In vitro assays show that CCD2 cleaves sequentially the 7,8 and 7′,8′ double bonds adjacent to a 3-OH-β-ionone ring and that the conversion of zeaxanthin to crocetin dialdehyde proceeds via the C30 intermediate 3-OH-β-apo-8′-carotenal. In contrast, zeaxanthin cleavage dioxygenase (ZCD), an enzyme previously claimed to mediate crocetin formation, did not cleave zeaxanthin or 3-OH-β-apo-8′-carotenal in the test systems used. Sequence comparison and structure prediction suggest that ZCD is an N-truncated CCD4 form, lacking one blade of the β-propeller structure conserved in all CCDs. These results constitute strong evidence that CCD2 catalyzes the first dedicated step in crocin biosynthesis. Similar to CCD1, CCD2 has a cytoplasmic localization, suggesting that it may cleave carotenoids localized in the chromoplast outer envelope.

Novel carotenoid cleavage dioxygenase catalyzes the first dedicated step in saffron crocin biosynthesis

KAUST Repository

Frusciante, Sarah

2014-08-05

Crocus sativus stigmas are the source of the saffron spice and accumulate the apocarotenoids crocetin, crocins, picrocrocin, and safranal, responsible for its color, taste, and aroma. Through deep transcriptome sequencing, we identified a novel dioxygenase, carotenoid cleavage dioxygenase 2 (CCD2), expressed early during stigma development and closely related to, but distinct from, the CCD1 dioxygenase family. CCD2 is the only identified member of a novel CCD clade, presents the structural features of a bona fide CCD, and is able to cleave zeaxanthin, the presumed precursor of saffron apocarotenoids, both in Escherichia coli and in maize endosperm. The cleavage products, identified through high-resolution mass spectrometry and comigration with authentic standards, are crocetin dialdehyde and crocetin, respectively. In vitro assays show that CCD2 cleaves sequentially the 7,8 and 7′,8′ double bonds adjacent to a 3-OH-β-ionone ring and that the conversion of zeaxanthin to crocetin dialdehyde proceeds via the C30 intermediate 3-OH-β-apo-8′-carotenal. In contrast, zeaxanthin cleavage dioxygenase (ZCD), an enzyme previously claimed to mediate crocetin formation, did not cleave zeaxanthin or 3-OH-β-apo-8′-carotenal in the test systems used. Sequence comparison and structure prediction suggest that ZCD is an N-truncated CCD4 form, lacking one blade of the β-propeller structure conserved in all CCDs. These results constitute strong evidence that CCD2 catalyzes the first dedicated step in crocin biosynthesis. Similar to CCD1, CCD2 has a cytoplasmic localization, suggesting that it may cleave carotenoids localized in the chromoplast outer envelope.

A new production technique for wear resistant ring-hammers

Directory of Open Access Journals (Sweden)

Li Shifeng

2011-11-01

Full Text Available Based on a great number of laboratory experiments, a new technique has been developed for producing wear resistant ring-hammers. In this technology, lost foam casting with iron sand was combined to make mold; a special alloy was used to inoculate the molten steel, and proper heat treatment was used to further improve mechanical properties of wear resistant ring-hammers. The influence of this new production technology on the microstructure and mechanical properties of wear resistant ring-hammers was studied. Results show that iron sand molding, having the inherent characteristic of sand molding, changes the type of metallic compounds, refines crystal grains and increases the fineness of microstructure. Practical experience verified that the properties of the ring-hammers produced with this new technique are as follows: tensile strength (Rm 720 MPa, impact toughness (ak > 210 J•cm-2 and hardness > 200 HB. After water quenching from 1,080℃ (holding for 4 h and tempering at 320℃ for 3 h, the best wear resistance is obtained, and the wear resistance is 1.6 times higher than that of common high manganese ring-hammers.

Capillary gas chromatographic analysis of mycolic acid cleavage products, cellular fatty acids, and alcohols of Mycobacterium xenopi.

OpenAIRE

Luquin, M; Lopez, F; Ausina, V

1989-01-01

The fatty acids, alcohols, and mycolic acids of 26 strains of Mycobacterium xenopi were studied by capillary gas chromatography and thin-layer chromatography. All strains contained alpha-, keto-, and omega-carboxymycolates. The primary mycolic acid cleavage product was hexacosanoic acid. The fatty acid patterns and, especially, the presence of 2-docosanol are characteristic markers of M. xenopi.

SKI2 mediates degradation of RISC 5′-cleavage fragments and prevents secondary siRNA production from miRNA targets in Arabidopsis

Science.gov (United States)

Branscheid, Anja; Marchais, Antonin; Schott, Gregory; Lange, Heike; Gagliardi, Dominique; Andersen, Stig Uggerhøj; Voinnet, Olivier; Brodersen, Peter

2015-01-01

Small regulatory RNAs are fundamental in eukaryotic and prokaryotic gene regulation. In plants, an important element of post-transcriptional control is effected by 20–24 nt microRNAs (miRNAs) and short interfering RNAs (siRNAs) bound to the ARGONAUTE1 (AGO1) protein in an RNA induced silencing complex (RISC). AGO1 may cleave target mRNAs with small RNA complementarity, but the fate of the resulting cleavage fragments remains incompletely understood. Here, we show that SKI2, SKI3 and SKI8, subunits of a cytoplasmic cofactor of the RNA exosome, are required for degradation of RISC 5′, but not 3′-cleavage fragments in Arabidopsis. In the absence of SKI2 activity, many miRNA targets produce siRNAs via the RNA-dependent RNA polymerase 6 (RDR6) pathway. These siRNAs are low-abundant, and map close to the cleavage site. In most cases, siRNAs were produced 5′ to the cleavage site, but several examples of 3′-spreading were also identified. These observations suggest that siRNAs do not simply derive from RDR6 action on stable 5′-cleavage fragments and hence that SKI2 has a direct role in limiting secondary siRNA production in addition to its function in mediating degradation of 5′-cleavage fragments. PMID:26464441

MODELS FOR MOUSE CHIMERA PRODUCTION: AGGREGATION OF ES CELLS WITH CLEAVAGE STAGE EMBRYOS

Directory of Open Access Journals (Sweden)

STANCA CLAUDIA

2007-01-01

Full Text Available In a mutant ES cells↔ wild-type embryo chimera, ES cells behave more like epiblastcells. They can contribute to the primitive ectoderm layers, which give rise to all theembryonic tissues and some extraembryonic tissues (Beddington and Robertson,1989, but not to trophectoderm or primitive endoderm. Using transgenic ES celllines, aggregated with cleavage stage host embryo, ES cells can integrate randomlyin the embryo proper. If they will be take part in the formation of ICM (inner cellmass, it will be possible to obtain germline chimera animals. To generate ES cells↔ cleavage stage host embryo chimeras, we used (CD-1 mice as donors of hostembryos as well as recipients of manipulated embryos. For chimera production, weused fluorescent-labeled ES cell line (CD1/EGFP, because in this case we canfollow the fate of ES cells during the embryonic development. We produced thechimers using “aggregation chimera technique”. 8 cells stage zona pellucida free,mouse embryos were aggregated in an aggregation plates, with a clump of ES cells(10 – 15 cells. The chimera embryos were cultivated for 24 hours in the incubator(at 37 °C, 5% CO2 in air. The chimera blastocysts resulted after cultivation, weretransferred to the uterus of the 2.5-dpc pseudo pregnant females.

MODELS FOR MOUSE CHIMERA PRODUCTION: AGGREGATION OF ES CELLS WITH CLEAVAGE STAGE EMBRYOS

Directory of Open Access Journals (Sweden)

CLAUDIA STANCA

2007-05-01

Full Text Available In a mutant ES cells↔ wild-type embryo chimera, ES cells behave more like epiblastcells. They can contribute to the primitive ectoderm layers, which give rise to all theembryonic tissues and some extraembryonic tissues (Beddington and Robertson,1989, but not to trophectoderm or primitive endoderm. Using transgenic ES celllines, aggregated with cleavage stage host embryo, ES cells can integrate randomlyin the embryo proper. If they will be take part in the formation of ICM (inner cellmass, it will be possible to obtain germline chimera animals. To generate ES cells↔ cleavage stage host embryo chimeras, we used (CD-1 mice as donors of hostembryos as well as recipients of manipulated embryos. For chimera production, weused fluorescent-labeled ES cell line (CD1/EGFP, because in this case we canfollow the fate of ES cells during the embryonic development. We produced thechimers using “aggregation chimera technique”. 8 cells stage zona pellucida free,mouse embryos were aggregated in an aggregation plates, with a clump of ES cells(10 – 15 cells. The chimera embryos were cultivated for 24 hours in the incubator(at 37 °C, 5% CO2 in air. The chimera blastocysts resulted after cultivation, weretransferred to the uterus of the 2.5-dpc pseudo pregnant females.

Bacterial biomass in warm-core Gulf Stream ring 82-B: mesoscale distributions, temporal changes and production

Science.gov (United States)

Ducklow, Hugh

1986-11-01

The distribution of bacterioplankton biomass and productivity in warm-core Gulf Stream ring 82-B generally corresponded to the physical and dynamical structure of the ring. Mean cell volumes were uniform for 4 months, but were larger by a factor of 2-3 in the high velocity (frontal) region (HVR) near the ring edge. As a result of this gradient and higher abundances, water column biomass and production were highest in the front, which appeared to be a local maximum in those properties. In this regard bacterioplankton contrasted strongly to phytoplankton, which exhibited strong local maxima at the center of the ring in June. In April when the water column inside the ring was isothermal to 450 m, bacterial biomass and production were low and uniform to 250 and 50 m, respectively. Bacterioplankton responded dramatically to the vernal restratification of the ring. In June when the surface layer was characterized by a strong pycnocline at 10-40 m, bacterial biomass and production often had strong subsurface maxima, and were 3 and 5 times greater than in April, respectively. Abundance exceeded 1.5 × 10 9 cells l -1 at ring center and exceeded 3 × 10 9 l -1 in the HVR. Turnover rates for the euphotic zone bacterioplankton as a whole were 0.24 d -1 in April, 0.56 d -1 in June, and 0.27 d -1 in August at ring center. Bacterial production averaged 12% of hourly primary production (range 1-32%), suggesting that bacteria control a significant and sometimes large portion of the carbon cycling in the euphotic zone. These data suggest that warm-core rings are sites of enhanced variability of bacterioplankton properties in the open sea. Furthermore, the data strongly support recent work showing that frontal zones are sites of locally enhanced bacterial biomass and production. In the ring system as a whole, the euphotic zone bacterioplankton biomass and production were comparable to and occasionally greater than the biomass and production of the >64 μm zooplankton, especially in

Fe-Catalyzed Oxidative Cleavage of Unsaturated Fatty Acids

NARCIS (Netherlands)

Spannring, P.

2013-01-01

The oxidative cleavage of unsaturated fatty acids into aldehydes or carboxylic acids gives access to valuable products. The products can be used as chemical building blocks, as emulsifiers or in the paint or polymer industry. Ozonolysis is applied industrially to cleave the fatty acid oleic acid

NMR characterization of foldedness for the production of E3 RING domains

NARCIS (Netherlands)

Huang, A.; de Jong, R.N.; Folkers, G.E.; Boelens, R.

2010-01-01

We summarize the use of NMR spectroscopy in the production and the screening of stability and foldedness of protein domains, and apply it to the RING domains of E3 ubiquitin-ligases. RING domains are involved in specific interactions with E2 ubiquitin-conjugating enzymes and thus play an essential

Supplementary data for the mechanism for cleavage of three typical glucosidic bonds induced by hydroxyl free radical

Directory of Open Access Journals (Sweden)

Yujie Dai

2017-12-01

Full Text Available The data presented in this article are related to the research article entitled “The mechanism for cleavage of three typical glucosidic bonds induced by hydroxyl free radical” (Dai et al., 2017 [1]. This article includes the structures of three kinds of disaccharides such as maltose, fructose and cellobiose, the diagrammatic sketch of the hydrogen abstraction reaction of the disaccharides by hydroxyl radical, the structure of the transition states for pyran ring opening of moiety A and cleavage of α(1→2 glycosidic bond starting from the hydrogen abstraction of C6–H in moiety A of sucrose, the transition state structure for cleavage of α(1→2 glycosidic bond starting from the hydrogen abstraction of C1′-H in moiety B of sucrose, the transition state structure, sketch for the reaction process and relative energy change of the reaction pathway for direct cleavage of α(1→4 glycosidic bond starting from hydrogen abstraction of C6′–H of moiety B of maltose.

Poly(ADP-ribose) polymerase-1 and its cleavage products differentially modulate cellular protection through NF-kB-dependent signaling

Science.gov (United States)

Castri, Paola; Lee, Yang-ja; Ponzio, Todd; Maric, Dragan; Spatz, Maria; Bembry, Joliet; Hallenbeck, John

2014-01-01

Poly(ADP-ribose) polymerase-1 (PARP-1) and its cleavage products regulate cell viability and NF-kB activity when expressed in neurons. PARP-1 cleavage generates a 24kDa (PARP-124) and an 89kDa fragment (PARP-189). Compared to WT (PARP-1WT), the expression of an uncleavable PARP-1 (PARP-1UNCL) or of PARP-124 conferred protection from oxygen/glucose deprivation (OGD) or OGD/restoration of oxygen and glucose (ROG) damage in vitro, whereas expression of PARP-189 was cytotoxic. Viability experiments were performed in SH-SY5Y, a human neuroblastoma cell line, as well as in rat primary cortical neurons. Following OGD, the higher viability in the presence of PARP-1UNCL or PARP-124 was not accompanied with decreased formation of poly(ADP-riboses) or higher NAD levels. PARP-1 is a known cofactor for NF-kB, hence we investigated whether PARP-1 cleavage influences the inflammatory response. All PARP-1 constructs mimicked PARP-1WT in regards to induction of NF-kB translocation into the nucleus and its increased activation during ischemic challenge. However, expression of PARP-189 construct induced significantly higher NF-kB activity than PARP-1WT; and the same was true for NF-kB-dependent iNOS promoter binding activity. At a protein level, PARP-1UNCL and PARP-124 decreased iNOS (and lower levels of iNOS transcript) and COX-2, and increased Bcl-xL. The increased levels of NF-kB and iNOS transcriptional activities, seen with cytotoxic PARP-189, were accompanied by higher protein expression of COX-2 and iNOS (and higher levels of iNOS transcript) and lower protein expression of Bcl-xL. Taken together, these findings suggest that PARP-1 cleavage products may regulate cellular viability and inflammatory responses in opposing ways during in vitro models of “ischemia”. PMID:24333653

Caspase activation increases beta-amyloid generation independently of caspase cleavage of the beta-amyloid precursor protein (APP).

Science.gov (United States)

Tesco, Giuseppina; Koh, Young Ho; Tanzi, Rudolph E

2003-11-14

The amyloid precursor protein (APP) undergoes "alternative" proteolysis mediated by caspases. Three major caspase recognition sites have been identified in the APP, i.e. one at the C terminus (Asp720) and two at the N terminus (Asp197 and Asp219). Caspase cleavage at Asp720 has been suggested as leading to increased production of Abeta. Thus, we set out to determine which putative caspase sites in APP, if any, are cleaved in Chinese hamster ovary cell lines concurrently with the increased Abeta production that occurs during apoptosis. We found that cleavage at Asp720 occurred concurrently with caspase 3 activation and the increased production of total secreted Abeta and Abeta1-42 in association with staurosporine- and etoposide-induced apoptosis. To investigate the contribution of caspase cleavage of APP to Abeta generation, we expressed an APP mutant truncated at Asp720 that mimics APP caspase cleavage at the C-terminal site. This did not increase Abeta generation but, in contrast, dramatically decreased Abeta production in Chinese hamster ovary cells. Furthermore, the ablation of caspase-dependent cleavage at Asp720, Asp197, and Asp219 (by site-directed mutagenesis) did not prevent enhanced Abeta production following etoposide-induced apoptosis. These findings indicate that the enhanced Abeta generation associated with apoptosis does not require cleavage of APP at its C-terminal (Asp720) and/or N-terminal caspase sites.

Aromatic products from reaction of lignin model compounds with UV-alkaline peroxide

International Nuclear Information System (INIS)

Sun, Y.P.; Wallis, A.F.A.; Nguyen, K.L.

1997-01-01

A series of guaiacyl and syringyl lignin model compounds and their methylated analogues were reacted with alkaline hydrogen peroxide while irradiating with UV light at 254 nm. The aromatic products obtained were investigated by gas chromatography-mass spectrometry (GC-MS). Guaiacol, syringol and veratrol gave no detectable aromatic products. However, syringol methyl ether gave small amounts of aromatic products, resulting from ring substitution and methoxyl displacement by hydroxyl radicals. Reaction of vanillin and syringaldehyde gave the Dakin reaction products, methoxy-1,4-hydroquinones, while reaction of their methyl ethers yielded benzoic acids. Acetoguaiacone, acetosyringone and their methyl ethers afforded several hydroxylated aromatic products, but no aromatic products were identified in the reaction mixtures from guaiacylpropane and syringylpropane. In contrast, veratrylpropane gave a mixture from which 17 aromatic hydroxylated compounds were identified. It is concluded that for phenolic lignin model compounds, particularly those possessing electrondonating aromatic ring substituents, ring-cleavage reactions involving superoxide radical anions are dominant, whereas for non-phenolic lignin models, hydroxylation reactions through attack of hydroxyl radicals prevail

Synthesis of a natural product-inspired eight-membered ring lactam library via ring-closing metathesis.

Science.gov (United States)

Brown, Neil; Xie, Baohan; Markina, Nataliya; Vandervelde, David; Perchellet, Jean-Pierre H; Perchellet, Elisabeth M; Crow, Kyle R; Buszek, Keith R

2008-09-01

We have prepared a novel speculative eight-membered lactam demonstration library based on the skeletal structure of the potent antitumor marine natural product octalactin A. The basic scaffold was readily constructed in a convergent fashion via ring-closing metathesis chemistry from the corresponding diene amides. A cursory examination of the biological properties of the library validates the relevance and significance of these structures.

Analysis by the reductive-cleavage method of linkage positions in a polysaccharide containing 4-linked D-glucopyranosyluronic residues.

Science.gov (United States)

Vodonik, S A; Gray, G R

1988-04-01

The fate of 4-linked D-glucopyranosyluronic residues under reductive-cleavage conditions was investigated by using the Klebsiella aerogenes type 54 strain A3 capsular polysaccharide. Treatment of the fully methylated polysaccharide with triethylsilane and trimethylsilyl trifluoromethanesulfonate in dichloromethane, followed by in situ acetylation, yielded 1,5-anhydro-2,3,4,6-tetra-O-methyl-D-glucitol, 3,4-di-O-acetyl-1,5-anhydro-2,6-di-O-methyl-D-glucitol, and 3-O-acetyl-1,5-anhydro-2,4-di-O-methyl-L-fucitol, as expected, but the expected product of reductive cleavage of the 4-linked D-glucopyranosyluronic residue, namely, methyl 3-O-acetyl-2,6-anhydro-4,5-di-O-methyl-L-gulonate, was not observed. Instead, methyl 2-O-acetyl-3,6-anhydro-4,5-di-O-methyl-L-gulonate (6) was identified as the sole product of reductive cleavage of the 4-linked D-glucopyranosyluronic residue. That compound 6 arose as a result of rearrangement during reductive cleavage rather than by reductive cleavage of a 5-linked D-glucofuranosyluronic residue, was established by reductive cleavage of the fully methylated polysaccharide following reduction of its ester groups with either lithium aluminum hydride or lithium aluminum deuteride. The products of the latter reductive cleavage were the same as before, except for the absence of 6 and the presence of 4,6-di-O-acetyl-1,5-anhydro-2,3-di-O-methyl-D-glucitol, or its 6,6-dideuterio isomer. Although the reductive-cleavage technique is suitable for the direct analysis of polysaccharides containing 4-linked D-glucopyranosyluronic residues, it does not establish whether the uronic residue is a 4-linked pyranoside or a 5-linked furanoside. The expected product is, however, derived from the 4-linked D-glucopyranosyluronic residue after sequential methylation, reduction of its ester group and reductive cleavage.

Calicivirus 3C-like proteinase inhibits cellular translation by cleavage of poly(A)-binding protein.

Science.gov (United States)

Kuyumcu-Martinez, Muge; Belliot, Gaël; Sosnovtsev, Stanislav V; Chang, Kyeong-Ok; Green, Kim Y; Lloyd, Richard E

2004-08-01

Caliciviruses are single-stranded RNA viruses that cause a wide range of diseases in both humans and animals, but little is known about the regulation of cellular translation during infection. We used two distinct calicivirus strains, MD145-12 (genus Norovirus) and feline calicivirus (FCV) (genus Vesivirus), to investigate potential strategies used by the caliciviruses to inhibit cellular translation. Recombinant 3C-like proteinases (r3CL(pro)) from norovirus and FCV were found to cleave poly(A)-binding protein (PABP) in the absence of other viral proteins. The norovirus r3CL(pro) PABP cleavage products were indistinguishable from those generated by poliovirus (PV) 3C(pro) cleavage, while the FCV r3CL(pro) products differed due to cleavage at an alternate cleavage site 24 amino acids downstream of one of the PV 3C(pro) cleavage sites. All cleavages by calicivirus or PV proteases separated the C-terminal domain of PABP that binds translation factors eIF4B and eRF3 from the N-terminal RNA-binding domain of PABP. The effect of PABP cleavage by the norovirus r3CL(pro) was analyzed in HeLa cell translation extracts, and the presence of r3CL(pro) inhibited translation of both endogenous and exogenous mRNAs. Translation inhibition was poly(A) dependent, and replenishment of the extracts with PABP restored translation. Analysis of FCV-infected feline kidney cells showed that the levels of de novo cellular protein synthesis decreased over time as virus-specific proteins accumulated, and cleavage of PABP occurred in virus-infected cells. Our data indicate that the calicivirus 3CL(pro), like PV 3C(pro), mediates the cleavage of PABP as part of its strategy to inhibit cellular translation. PABP cleavage may be a common mechanism among certain virus families to manipulate cellular translation.

Evolutionarily distinct carotenoid cleavage dioxygenases are responsible for crocetin production in Buddleja davidii.

Science.gov (United States)

Ahrazem, Oussama; Diretto, Gianfranco; Argandoña, Javier; Rubio-Moraga, Ángela; Julve, José Manuel; Orzáez, Diego; Granell, Antonio; Gómez-Gómez, Lourdes

2017-07-20

Crocetin, one of the few colored apocarotenoids known in nature, is present in flowers and fruits and has long been used medicinally and as a colorant. Saffron is the main source of crocetin, although a few other plants produce lower amounts of this apocarotenoid. Notably, Buddleja davidii accumulates crocetin in its flowers. Recently, a carotenoid dioxygenase cleavage enzyme, CCD2, has been characterized as responsible for crocetin production in Crocus species. We searched for CCD2 homologues in B. davidii and identified several CCD enzymes from the CCD1 and CCD4 subfamilies. Unexpectedly, two out of the three CCD4 enzymes, namely BdCCD4.1 and BdCCD4.3, showed 7,8;7',8' activity in vitro and in vivo over zeaxanthin. In silico analyses of these enzymes and CCD2 allowed the determination of key residues for this activity. Both BdCCD4 genes are highly expressed during flower development and transcripts levels parallel the accumulation of crocins in the petals. Phylogenetic analysis showed that BdCCD4.2 grouped with almost all the characterized CCD4 enzymes, while BdCCD4.1 and BdCCD4.3 form a new sub-cluster together with CCD4 enzymes from certain Lamiales species. The present study indicates that convergent evolution led to the acquisition of 7,8;7',8' apocarotenoid cleavage activity in two separate CCD enzyme families. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Polycystin-1 Cleavage and the Regulation of Transcriptional Pathways

Science.gov (United States)

Merrick, David; Bertuccio, Claudia A.; Chapin, Hannah C.; Lal, Mark; Chauvet, Veronique; Caplan, Michael J.

2013-01-01

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic cause of end stage renal disease, affecting ~1 in 1,000 people. The disease is characterized by the development of numerous large fluid filled renal cysts over the course of decades. These cysts compress the surrounding renal parenchyma and impair its function. Mutations in two genes are responsible for ADPKD. The protein products of both of these genes, polycystin-1 and polycystin-2, localize to the primary cilium and participate in a wide variety of signaling pathways. Polycystin-1 undergoes several proteolytic cleavages that produce fragments that manifest biological activities. Recent results suggest that the production of polycystin-1 cleavage fragments is necessary and sufficient to account for at least some, although certainly not all, of the physiological functions of the parent protein. PMID:23824180

Vertebrate Embryonic Cleavage Pattern Determination.

Science.gov (United States)

Hasley, Andrew; Chavez, Shawn; Danilchik, Michael; Wühr, Martin; Pelegri, Francisco

2017-01-01

The pattern of the earliest cell divisions in a vertebrate embryo lays the groundwork for later developmental events such as gastrulation, organogenesis, and overall body plan establishment. Understanding these early cleavage patterns and the mechanisms that create them is thus crucial for the study of vertebrate development. This chapter describes the early cleavage stages for species representing ray-finned fish, amphibians, birds, reptiles, mammals, and proto-vertebrate ascidians and summarizes current understanding of the mechanisms that govern these patterns. The nearly universal influence of cell shape on orientation and positioning of spindles and cleavage furrows and the mechanisms that mediate this influence are discussed. We discuss in particular models of aster and spindle centering and orientation in large embryonic blastomeres that rely on asymmetric internal pulling forces generated by the cleavage furrow for the previous cell cycle. Also explored are mechanisms that integrate cell division given the limited supply of cellular building blocks in the egg and several-fold changes of cell size during early development, as well as cytoskeletal specializations specific to early blastomeres including processes leading to blastomere cohesion. Finally, we discuss evolutionary conclusions beginning to emerge from the contemporary analysis of the phylogenetic distributions of cleavage patterns. In sum, this chapter seeks to summarize our current understanding of vertebrate early embryonic cleavage patterns and their control and evolution.

Stimulation of NADH-dependent microsomal DNA strand cleavage by rifamycin SV.

Science.gov (United States)

Kukiełka, E; Cederbaum, A I

1995-04-15

Rifamycin SV is an antibiotic anti-bacterial agent used in the treatment of tuberculosis. This drug can autoxidize, especially in the presence of metals, and generate reactive oxygen species. A previous study indicated that rifamycin SV can increase NADH-dependent microsomal production of reactive oxygen species. The current study evaluated the ability of rifamycin SV to interact with iron and increase microsomal production of hydroxyl radical, as detected by conversion of supercoiled plasmid DNA into the relaxed open circular state. The plasmid used was pBluescript II KS(-), and the forms of DNA were separated by agarose-gel electrophoresis. Incubation of rat liver microsomes with plasmid plus NADH plus ferric-ATP caused DNA strand cleavage. The addition of rifamycin SV produced a time- and concentration-dependent increase in DNA-strand cleavage. No stimulation by rifamycin SV occurred in the absence of microsomes, NADH or ferric-ATP. Stimulation occurred with other ferric complexes besides ferric-ATP, e.g. ferric-histidine, ferric-citrate, ferric-EDTA, and ferric-(NH4)2SO4. Rifamycin SV did not significantly increase the high rates of DNA strand cleavage found with NADPH as the microsomal reductant. The stimulation of NADH-dependent microsomal DNA strand cleavage was completely blocked by catalase, superoxide dismutase, GSH and a variety of hydroxyl-radical-scavenging agents, but not by anti-oxidants that prevent microsomal lipid peroxidation. Redox cycling agents, such as menadione and paraquat, in contrast with rifamycin SV, stimulated the NADPH-dependent reaction; menadione and rifamycin SV were superior to paraquat in stimulating the NADH-dependent reaction. These results indicate that rifamycin SV can, in the presence of an iron catalyst, increase microsomal production of reactive oxygen species which can cause DNA-strand cleavage. In contrast with other redox cycling agents, the stimulation by rifamycin SV is more pronounced with NADH than with NADPH as the

Computational study of hydrogen shifts and ring-opening mechanisms in α-pinene ozonolysis products

DEFF Research Database (Denmark)

Kurtén, Theo; Rissanen, Matti P.; Mackeprang, Kasper

2015-01-01

, sterically unhindered) H-shifts of all four peroxy radicals formed in the ozonolysis of α-pinene using density functional (ωB97XD) and coupled cluster [CCSD(T)-F12] theory. In contrast to the related but chemically simpler cyclohexene ozonolysis system, none of the calculated H-shifts have rate constants...... products in the α-pinene ozonolysis system, additional ring-opening reaction mechanisms breaking the cyclobutyl ring are therefore needed. We further investigate possible uni- and bimolecular pathways for opening the cyclobutyl ring in the α-pinene ozonolysis system....

Liberation of methyl acrylate from metallalactone complexes via M-O ring opening (M = Ni, Pd) with methylation agents

KAUST Repository

Lee, S. Y Tina; Ghani, Amylia Abdul; D'Elia, Valerio; Cokoja, Mirza; Herrmann, Wolfgang A.; Basset, Jean-Marie; Kü hn, Fritz

2013-01-01

Ring opening of various nickela- and palladalactones induced by the cleavage of the M-O bond by methyl trifluoromethanesulfonate (MeOTf) and methyl iodide (MeI) is examined. Experimental evidence supports the mechanism of ring opening by the alkylating agent followed by β-H elimination leading to methyl acrylate and a metal-hydride species. MeOTf shows by far higher efficiency in the lactone ring opening than any other methylating agent including the previously reported methyl iodide. © 2013 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

Carbon Dioxide Utilization by the Five-Membered Ring Products of Cyclometalation Reactions

Science.gov (United States)

Omae, Iwao

2016-01-01

In carbon dioxide utilization by cyclometalated five-membered ring products, the following compounds are used in four types of applications: 1. 2-Phenylpyrazole iridium compounds, pincer phosphine iridium compounds and 2-phenylimidazoline iridium compounds are used as catalysts for both formic acid production from CO2 and H2, and hydrogen production from the formic acid. This formic acid can be a useful agent for H2 production and storage for fuel cell electric vehicles. 2. Other chemicals, e.g., dimethyl carbonate, methane, methanol and CO, are produced with dimethylaminomethylphenyltin compounds, pincer phosphine iridium compounds, pincer phosphine nickel compound and ruthenium carbene compound or 2-phenylpyridine iridium compounds, and phenylbenzothiazole iridium compounds as the catalysts for the reactions with CO2. 3. The five-membered ring intermediates of cyclometalation reactions with the conventional substrates react with carbon dioxide to afford their many types of carboxylic acid derivatives. 4. Carbon dioxide is easily immobilized at room temperature with immobilizing agents such as pincer phosphine nickel compounds, pincer phosphine palladium compounds, pincer N,N-dimethylaminomethyltin compounds and tris(2-pyridylthio)methane zinc compounds. PMID:28503084

Carotenoid-cleavage activities of crude enzymes from Pandanous amryllifolius.

Science.gov (United States)

Ningrum, Andriati; Schreiner, Matthias

2014-11-01

Carotenoid degradation products, known as norisoprenoids, are aroma-impact compounds in several plants. Pandan wangi is a common name of the shrub Pandanus amaryllifolius. The genus name 'Pandanus' is derived from the Indonesian name of the tree, pandan. In Indonesia, the leaves from the plant are used for several purposes, e.g., as natural colorants and flavor, and as traditional treatments. The aim of this study was to determine the cleavage of β-carotene and β-apo-8'-carotenal by carotenoid-cleavage enzymes isolated from pandan leaves, to investigate dependencies of the enzymatic activities on temperature and pH, to determine the enzymatic reaction products by using Headspace Solid Phase Microextraction Gas Chromatography/Mass Spectrophotometry (HS-SPME GC/MS), and to investigate the influence of heat treatment and addition of crude enzyme on formation of norisoprenoids. Crude enzymes from pandan leaves showed higher activity against β-carotene than β-apo-8'-carotenal. The optimum temperature of crude enzymes was 70°, while the optimum pH value was 6. We identified β-ionone as the major volatile reaction product from the incubations of two different carotenoid substrates, β-carotene and β-apo-8'-carotenal. Several treatments, e.g., heat treatment and addition of crude enzymes in pandan leaves contributed to the norisoprenoid content. Our findings revealed that the crude enzymes from pandan leaves with carotenoid-cleavage activity might provide a potential application, especially for biocatalysis, in natural-flavor industry. Copyright © 2014 Verlag Helvetica Chimica Acta AG, Zürich.

Design, synthesis and structure-activity relationships studies on the D ring of the natural product triptolide.

Science.gov (United States)

Xu, Hongtao; Tang, Huanyu; Feng, Huijin; Li, Yuanchao

2014-02-01

Triptolide is a diterpene triepoxide natural product isolated from Tripterygium wilfordii Hook F, a traditional Chinese medicinal herb. Triptolide has previously been shown to possess antitumor, anti-inflammatory, immunosuppressive, and antifertility activities. Earlier reports suggested that the five-membered unsaturated lactone ring (D ring) is essential for potent cytotoxicity, however, to the best of our knowledge, systematic structure-activity relationship studies have not yet been reported. Here, four types of D ring-modified triptolide analogues were designed, synthesized and evaluated against human ovarian (SKOV-3) and prostate (PC-3) carcinoma cell lines. The results suggest that the D ring is essential to potency, however it can be modified, for example to C18 hydrogen bond acceptor and/or donor furan ring analogues, without complete loss of cytotoxic activity. Interestingly, evaluation of the key series of C19 analogues showed that this site is exquisitely sensitive to polarity. Together, these results will guide further optimization of this natural product lead compound for the development of potent and potentially clinically useful triptolide analogues. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

New insights into the by-product fatigue mechanism of the photo-induced ring-opening in diarylethenes.

Science.gov (United States)

Mendive-Tapia, David; Perrier, Aurélie; Bearpark, Michael J; Robb, Michael A; Lasorne, Benjamin; Jacquemin, Denis

2014-09-14

The photochromic properties of diarylethenes, some of the most studied class of molecular switches, are known to be controlled by non-adiabatic decay at a conical intersection seam. Nevertheless, as their fatigue-reaction mechanism - leading to non-photochromic products - is yet to be understood, we investigate the photo-chemical formation of the so-called by-product isomer using three complementary computational methods (MMVB, CASSCF and CASPT2) on three model systems of increasing complexity. We show that for the ring-opening reaction a transition state on S1(2A) involving bond breaking of the penta-ring leads to a low energy S1(2A)/S0(1A) conical intersection seam, which lies above one of the transition states leading to the by-product isomer on the ground state. Therefore, radiationless decay and subsequent side-product formation can take place explaining the photo-degradation responsible for the by-product generation in diarylethene-type molecules. The effect of dynamic electron correlation and the possible role of inter-system crossing along the penta-ring opening coordinate are discussed as well.

Post-transcription cleavage generates the 3' end of F17R transcripts in vaccinia virus

International Nuclear Information System (INIS)

D'Costa, Susan M.; Antczak, James B.; Pickup, David J.; Condit, Richard C.

2004-01-01

Most vaccinia virus intermediate and late mRNAs possess 3' ends that are extremely heterogeneous in sequence. However, late mRNAs encoding the cowpox A-type inclusion protein (ATI), the second largest subunit of the RNA polymerase, and the late telomeric transcripts possess homogeneous 3' ends. In the case of the ATI mRNA, it has been shown that the homogeneous 3' end is generated by a post-transcriptional endoribonucleolytic cleavage event. We have determined that the F17R gene also produces homogeneous transcripts generated by a post-transcriptional cleavage event. Mapping of in vivo mRNA shows that the major 3' end of the F17R transcript maps 1262 nt downstream of the F17R translational start site. In vitro transcripts spanning the in vivo 3' end are cleaved in an in vitro reaction using extracts from virus infected cells, and the site of cleavage is the same both in vivo and in vitro. Cleavage is not observed using extract from cells infected in the presence of hydroxyurea; therefore, the cleavage factor is either virus-coded or virus-induced during the post-replicative phase of virus replication. The cis-acting sequence responsible for cleavage is orientation specific and the factor responsible for cleavage activity has biochemical properties similar to the factor required for cleavage of ATI transcripts. Partially purified cleavage factor generates cleavage products of expected size when either the ATI or F17R substrates are used in vitro, strongly suggesting that cleavage of both transcripts is mediated by the same factor

Amyloid-β production via cleavage of amyloid-β protein precursor is modulated by cell density.

Science.gov (United States)

Zhang, Can; Browne, Andrew; Divito, Jason R; Stevenson, Jesse A; Romano, Donna; Dong, Yuanlin; Xie, Zhongcong; Tanzi, Rudolph E

2010-01-01

Mounting evidence suggests that Alzheimer's disease (AD) is caused by the accumulation of the small peptide, amyloid-β (Aβ), a proteolytic cleavage product of amyloid-β protein precursor (AβPP). Aβ is generated through a serial cleavage of AβPP by β- and γ-secretase. Aβ40 and Aβ42 are the two main components of amyloid plaques in AD brains, with Aβ42 being more prone to aggregation. AβPP can also be processed by α-secretase, which cleaves AβPP within the Aβ sequence, thereby preventing the generation of Aβ. Little is currently known regarding the effects of cell density on AβPP processing and Aβ generation. Here we assessed the effects of cell density on AβPP processing in neuronal and non-neuronal cell lines, as well as mouse primary cortical neurons. We found that decreased cell density significantly increases levels of Aβ40, Aβ42, total Aβ, and the ratio of Aβ42: Aβ40. These results also indicate that cell density is a significant modulator of AβPP processing. Overall, these findings carry profound implications for both previous and forthcoming studies aiming to assess the effects of various conditions and genetic/chemical factors, e.g., novel drugs on AβPP processing and Aβ generation in cell-based systems. Moreover, it is interesting to speculate whether cell density changes in vivo may also affect AβPP processing and Aβ levels in the AD brain.

Cleavage and creep fracture of rock salt

International Nuclear Information System (INIS)

Chan, K.S.; Munson, D.E.; Bodner, S.R.

1996-01-01

The dominant failure mechanism in rock salt at ambient temperature is either cleavage or creep fracture. Since the transition of creep fracture to cleavage in a compressive stress field is not well understood, failure of rock salt by cleavage and creep fracture is analyzed in this paper to elucidate the effect of stress state on the competition between these two fracture mechanisms. For cleavage fracture, a shear crack is assumed to cause the formation and growth of a symmetric pair of wing cracks in a predominantly compressive stress field. The conditions for wing-crack instability are derived and presented as the cleavage fracture boundary in the fracture mechanism map. Using an existing creep fracture model, stress conditions for the onset of creep fracture and isochronous failure curves of specified times-to-rupture are calculated and incorporated into the fracture mechanism map. The regimes of dominance by cleavage and creep fracture are established and compared with experimental data. The result indicates that unstable propagation of cleavage cracks occurs only in the presence of tensile stress. The onset of creep fracture is promoted by a tensile stress, but can be totally suppressed by a high confining pressure. Transition of creep fracture to cleavage occurs when critical conditions of stress difference and tensile stress for crack instability are exceeded

Token ring technology report

CERN Document Server

2013-01-01

Please note this is a Short Discount publication. This report provides an overview of the IBM Token-Ring technology and products built by IBM and compatible vendors. It consists of two sections: 1. A summary of the design trade-offs for the IBM Token-Ring. 2. A summary of the products of the major token-ring compatible vendors broken down by adapters and components, wiring systems, testing, and new chip technology.

Lipase catalyzed HEMA initiated ring-opening polymerization: In situ formation of mixed polyester methacrylates by transesterification

NARCIS (Netherlands)

Takwa, M.; Xiao, Y.; Simpson, N.; Malmstrom, E.; Hult, K.; Koning, C.E.; Heise, A.; Martinelle, M.

2008-01-01

2-Hydroxyethyl methacrylate (HEMA) was used as initiator for the enzymatic ring-opening polymerization (ROP) of ¿-pentadecalactone (PDL) and e-caprolactone (CL). The lipase B from Candida antarctica was found to catalyze the cleavage of the ester bond in the HEMA end group of the formed polyesters,

Influence of ring growth rate on damage development in hot ring rolling

NARCIS (Netherlands)

Wang, C.; Geijselaers, H. J.M.; Omerspahic, E.; Recina, V.; van den Boogaard, A. H.

2015-01-01

As an incremental forming process of bulk metal, ring rolling provides a cost effective process route to manufacture seamless rings. In the production of hot rolled rings, defects such as porosity can sometimes be found in high alloyed steel, manufactured from ingots having macro-segregation. For

On zero divisor graph of unique product monoid rings over Noetherian reversible ring

Directory of Open Access Journals (Sweden)

Ebrahim Hashemi

2016-02-01

Full Text Available Let $R$ be an associative ring with identity and $Z^*(R$ be its set of non-zero zero divisors.  The zero-divisor graph of $R$, denoted by $Gamma(R$, is the graph whose vertices are the non-zero  zero-divisors of  $R$, and two distinct vertices $r$ and $s$ are adjacent if and only if $rs=0$ or $sr=0$.  In this paper, we bring some results about undirected zero-divisor graph of a monoid ring over reversible right (or left Noetherian ring $R$. We essentially classify the diameter-structure of this graph and show that $0leq mbox{diam}(Gamma(Rleq mbox{diam}(Gamma(R[M]leq 3$. Moreover, we give a characterization for the possible diam$(Gamma(R$ and diam$(Gamma(R[M]$, when $R$ is a reversible Noetherian ring and $M$ is a u.p.-monoid. Also, we study relations between the girth of $Gamma(R$ and that of $Gamma(R[M]$.

Groups, rings, modules

CERN Document Server

Auslander, Maurice

2014-01-01

This classic monograph is geared toward advanced undergraduates and graduate students. The treatment presupposes some familiarity with sets, groups, rings, and vector spaces. The four-part approach begins with examinations of sets and maps, monoids and groups, categories, and rings. The second part explores unique factorization domains, general module theory, semisimple rings and modules, and Artinian rings. Part three's topics include localization and tensor products, principal ideal domains, and applications of fundamental theorem. The fourth and final part covers algebraic field extensions

Preparation for electron ring - plasma ring merging experiments in RECE-MERGE

International Nuclear Information System (INIS)

Taggart, D.; Sekiguchi, A.; Fleischmann, H.H.

1986-01-01

The formation of a mixed-CT using relativistic electron rings and gun-produced plasma rings by MERGE-ing them axially is simulated. This process is similar to the axial stacking of relativistic electron rings in RECE-Christa. The results of their first plasm production experiment are reported here. After study of the gun-produced plasma's properties is completed, the gun will be mounted at the downstream end of the vacuum tank and the source of relativistic electron rings will be at the upstream end. The two rings, formed at opposite ends of the tank, will be translated axially and merged

Biogeochemical modelling vs. tree-ring data - comparison of forest ecosystem productivity estimates

Science.gov (United States)

Zorana Ostrogović Sever, Maša; Barcza, Zoltán; Hidy, Dóra; Paladinić, Elvis; Kern, Anikó; Marjanović, Hrvoje

2017-04-01

Forest ecosystems are sensitive to environmental changes as well as human-induce disturbances, therefore process-based models with integrated management modules represent valuable tool for estimating and forecasting forest ecosystem productivity under changing conditions. Biogeochemical model Biome-BGC simulates carbon, nitrogen and water fluxes, and it is widely used for different terrestrial ecosystems. It was modified and parameterised by many researchers in the past to meet the specific local conditions. In this research, we used recently published improved version of the model Biome-BGCMuSo (BBGCMuSo), with multilayer soil module and integrated management module. The aim of our research is to validate modelling results of forest ecosystem productivity (NPP) from BBGCMuSo model with observed productivity estimated from an extensive dataset of tree-rings. The research was conducted in two distinct forest complexes of managed Pedunculate oak in SE Europe (Croatia), namely Pokupsko basin and Spačva basin. First, we parameterized BBGCMuSo model at a local level using eddy-covariance (EC) data from Jastrebarsko EC site. Parameterized model was used for the assessment of productivity on a larger scale. Results of NPP assessment with BBGCMuSo are compared with NPP estimated from tree ring data taken from trees on over 100 plots in both forest complexes. Keywords: Biome-BGCMuSo, forest productivity, model parameterization, NPP, Pedunculate oak

Trichomonas vaginalis Metalloproteinase Induces mTOR Cleavage of SiHa Cells

Science.gov (United States)

Quan, Juan-Hua; Choi, In-Wook; Yang, Jung-Bo; Zhou, Wei; Cha, Guang-Ho; Zhou, Yu; Ryu, Jae-Sook

2014-01-01

Trichomonas vaginalis secretes a number of proteases which are suspected to be the cause of pathogenesis; however, little is understood how they manipulate host cells. The mammalian target of rapamycin (mTOR) regulates cell growth, cell proliferation, cell motility, cell survival, protein synthesis, and transcription. We detected various types of metalloproteinases including GP63 protein from T. vaginalis trophozoites, and T. vaginalis GP63 metalloproteinase was confirmed by sequencing and western blot. When SiHa cells were stimulated with live T. vaginalis, T. vaginalis excretory-secretory products (ESP) or T. vaginalis lysate, live T. vaginalis and T. vaginalis ESP induced the mTOR cleavage in both time- and parasite load-dependent manner, but T. vaginalis lysate did not. Pretreatment of T. vaginalis with a metalloproteinase inhibitor, 1,10-phenanthroline, completely disappeared the mTOR cleavage in SiHa cells. Collectively, T. vaginalis metallopeptidase induces host cell mTOR cleavage, which may be related to survival of the parasite. PMID:25548410

Microstructure and cleavage in lath martensitic steels

International Nuclear Information System (INIS)

Morris, John W Jr; Kinney, Chris; Pytlewski, Ken; Adachi, Y

2013-01-01

In this paper we discuss the microstructure of lath martensitic steels and the mechanisms by which it controls cleavage fracture. The specific experimental example is a 9Ni (9 wt% Ni) steel annealed to have a large prior austenite grain size, then examined and tested in the as-quenched condition to produce a relatively coarse lath martensite. The microstructure is shown to approximate the recently identified ‘classic’ lath martensite structure: prior austenite grains are divided into packets, packets are subdivided into blocks, and blocks contain interleaved laths whose variants are the two Kurjumov–Sachs relations that share the same Bain axis of the transformation. When the steel is fractured in brittle cleavage, the laths in the block share {100} cleavage planes and cleave as a unit. However, cleavage cracks deflect or blunt at the boundaries between blocks with different Bain axes. It follows that, as predicted, the block size governs the effective grain size for cleavage. (paper)

Study of chi production properties at the CERN Intersecting Storage Rings

International Nuclear Information System (INIS)

Kourkoumelis, C.; Resvanis, L.K.; Filippas, T.A.; Fokitis, E.; Fabjan, C.W.; Fields, T.; Fowler, E.; Lissauer, D.; Mannelli, I.; Mouzourakis, P.; Nappi, A.; Willis, W.J.; Goldberg, M.

1979-01-01

The inclusive production of electron pairs with and without additional photons was measured at the CERN Intersecting Storage Rings (ISR). The investigation of J/psi particles with associated photons indicated that 47 +- 8% of the J/psi were produced via the photonic decay of one of the chi(3.5) states. The upper limit of the production cross-section ratio times the branching ratio into electron pairs of psi' relative to J/psi was found to be 2% at centre-of-mass energy of √s = 62 GeV. (Auth.)

Ion production and trapping in electron rings

International Nuclear Information System (INIS)

Gluckstern, R.C.; Ruggiero, A.G.

1979-08-01

The electron beam in the VUV and X-ray rings of NSLS will ionize residual gas by collisions. Positive ions will be produced with low velocity, and will be attracted by the electron beam to the beam axis. If they are trapped in stable (transverse) orbits, they may accumulate, thereby increasing the ν/sub x,z/ of the individual electrons. Since the accumulated ions are unlikely to be of uniform density, a spread in ν/sub x,z/ will also occur. Should these effects be serious, it may be necessary to introduce clearing electrodes, although this may increase Z/n in the rings, thereby adding to longitudinal instability problems. The seriousness of the above effect for the VUV and X-ray rings is estimated

Cleavage sites in the polypeptide precursors of poliovirus protein P2-X

International Nuclear Information System (INIS)

Selmer, B.L.; Hanecak, R.; Anderson, C.W.; Wimmer, E.

1981-01-01

Partial amino-terminal sequence analysis has been performed on the three major polypeptide products (P2-3b, P2-5b, and P2-X) from the central region (P2) of the poliovirus polyprotein, and this analysis precisely locates the amino termini of these products with respect to the nucleotide sequence of the poliovirus RNA genome. Like most of the products of the replicase region (P3), the amino termini of P2-5b and P2-X are generated by cleavage between glutamine and glycine residues. Thus, P2-5b and P2-X are probably both produced by the action of a singly (virus-encoded.) proteinase. The amino terminus of P2-3b, on the other hand, is produced by a cleavage between the carboxy-terminal tyrosine of VP1 and the glycine encoded by nucleotides 3381-3383. This result may suggest that more than one proteolytic activity is required for the complete processing of the poliovirus polyprotein

Modeling and inferring cleavage patterns in proliferating epithelia.

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Ankit B Patel

2009-06-01

Full Text Available The regulation of cleavage plane orientation is one of the key mechanisms driving epithelial morphogenesis. Still, many aspects of the relationship between local cleavage patterns and tissue-level properties remain poorly understood. Here we develop a topological model that simulates the dynamics of a 2D proliferating epithelium from generation to generation, enabling the exploration of a wide variety of biologically plausible cleavage patterns. We investigate a spectrum of models that incorporate the spatial impact of neighboring cells and the temporal influence of parent cells on the choice of cleavage plane. Our findings show that cleavage patterns generate "signature" equilibrium distributions of polygonal cell shapes. These signatures enable the inference of local cleavage parameters such as neighbor impact, maternal influence, and division symmetry from global observations of the distribution of cell shape. Applying these insights to the proliferating epithelia of five diverse organisms, we find that strong division symmetry and moderate neighbor/maternal influence are required to reproduce the predominance of hexagonal cells and low variability in cell shape seen empirically. Furthermore, we present two distinct cleavage pattern models, one stochastic and one deterministic, that can reproduce the empirical distribution of cell shapes. Although the proliferating epithelia of the five diverse organisms show a highly conserved cell shape distribution, there are multiple plausible cleavage patterns that can generate this distribution, and experimental evidence suggests that indeed plants and fruitflies use distinct division mechanisms.

Auto-production of biosurfactants reverses the coffee ring effect in a bacterial system

Science.gov (United States)

Sempels, Wouter; de Dier, Raf; Mizuno, Hideaki; Hofkens, Johan; Vermant, Jan

2013-04-01

The deposition of material at the edge of evaporating droplets, known as the ‘coffee ring effect’, is caused by a radially outward capillary flow. This phenomenon is common to a wide array of systems including colloidal and bacterial systems. The role of surfactants in counteracting these coffee ring depositions is related to the occurrence of local vortices known as Marangoni eddies. Here we show that these swirling flows are universal, and not only lead to a uniform deposition of colloids but also occur in living bacterial systems. Experiments on Pseudomonas aeruginosa suggest that the auto-production of biosurfactants has an essential role in creating a homogeneous deposition of the bacteria upon drying. Moreover, at biologically relevant conditions, intricate time-dependent flows are observed in addition to the vortex regime, which are also effective in reversing the coffee ring effect at even lower surfactant concentrations.

Influence of the austenitizing temperature in the cleavage facet size of Niocor 2

International Nuclear Information System (INIS)

Darwish, F.A.I.; Teixeira, J.C.G.; Fernandes, R.A.; Juer, S.

1983-01-01

Convetional Charpy specimens of Niocor 2 steel cooled in air from various austenitizing temperatures were fractured at -196 0 C so as to insure failure by cleavage. The cleavage facet size distribution was determined and then correlated with the grain size and other aspects of the microstructure. The results that the average facet size can be increased through a coarsening of the microstructure. For the case where the γ→α transformation products are predominantely acicular, the facet size is shown to depend on substructural aspects primarily the lath packet size. (Author) [pt

Drosha regulates gene expression independently of RNA cleavage function

DEFF Research Database (Denmark)

Gromak, Natalia; Dienstbier, Martin; Macias, Sara

2013-01-01

Drosha is the main RNase III-like enzyme involved in the process of microRNA (miRNA) biogenesis in the nucleus. Using whole-genome ChIP-on-chip analysis, we demonstrate that, in addition to miRNA sequences, Drosha specifically binds promoter-proximal regions of many human genes in a transcription......-dependent manner. This binding is not associated with miRNA production or RNA cleavage. Drosha knockdown in HeLa cells downregulated nascent gene transcription, resulting in a reduction of polyadenylated mRNA produced from these gene regions. Furthermore, we show that this function of Drosha is dependent on its N......-terminal protein-interaction domain, which associates with the RNA-binding protein CBP80 and RNA Polymerase II. Consequently, we uncover a previously unsuspected RNA cleavage-independent function of Drosha in the regulation of human gene expression....

Multiplicative Structure and Hecke Rings of Generator Matrices for Codes over Quotient Rings of Euclidean Domains

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Hajime Matsui

2017-12-01

Full Text Available In this study, we consider codes over Euclidean domains modulo their ideals. In the first half of the study, we deal with arbitrary Euclidean domains. We show that the product of generator matrices of codes over the rings mod a and mod b produces generator matrices of all codes over the ring mod a b , i.e., this correspondence is onto. Moreover, we show that if a and b are coprime, then this correspondence is one-to-one, i.e., there exist unique codes over the rings mod a and mod b that produce any given code over the ring mod a b through the product of their generator matrices. In the second half of the study, we focus on the typical Euclidean domains such as the rational integer ring, one-variable polynomial rings, rings of Gaussian and Eisenstein integers, p-adic integer rings and rings of one-variable formal power series. We define the reduced generator matrices of codes over Euclidean domains modulo their ideals and show their uniqueness. Finally, we apply our theory of reduced generator matrices to the Hecke rings of matrices over these Euclidean domains.

Tinkering at the main-ring lattice

Energy Technology Data Exchange (ETDEWEB)

Ohnuma, S.

1982-08-23

To improve production of usable antiprotons using the proton beam from the main ring and the lossless injection of cooled antiprotons into the main ring, modifications of the main ring lattice are recommended.

Secondary isotope effects on alpha-cleavage reactions

International Nuclear Information System (INIS)

Ingemann, S.; Hammerum, S.

1980-01-01

Kinetic deuterium isotope effects on mass spectral reactions have in several instances been utilized to provide structural information and to answer mechanistic questions. Typically, the influence of the deuterium label on the rate of one of a number of competing reactions has been studied. Secondary isotope effects have usually been assumed to be relatively insignificant in comparison with the observed kinetic effects, even though various workers have shown that secondary isotope effects may indeed exert a considerable influence on the rates of competing simple cleavages. Recent studies have provided quantitative data to show that the mere presence of deuterium atoms up to six bonds away may influence the rate of a simple cleavage reaction. In relation to an investigation of rearrangements accompanying simple cleavage reactions, a semi-quantitative measure was needed of the variation of the secondary isotope effect with the number of bonds between the deuterium label and the point of rupture. The influence has therefore been examined of the presence of remote deuterium atoms on a typical simple cleavage reaction, the α-cleavage of aliphatic amines. As a model compound, N-methyldipentylamine was chosen, systematically labelled with deuterium. (author)

Regulation of proteolytic cleavage of brain-derived neurotrophic factor precursor by antidepressants in human neuroblastoma cells

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Lin PY

2015-10-01

Full Text Available Pao-Yen Lin1,2 1Department of Psychiatry, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, 2Center for Translational Research in Biomedical Sciences, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan Abstract: Evidence has supported the role of brain-derived neurotrophic factor (BDNF in antidepressant effect. The precursor of BDNF (proBDNF often exerts opposing biological effects on mature BDNF (mBDNF. Hence, the balance between proBDNF and mBDNF might be critical in total neurotrophic effects, leading to susceptibility to or recovery from depression. In the current study, we measured the protein expression levels of proBDNF, and its proteolytic products, truncated BDNF, and mBDNF, in human SH-SY5Y cells treated with different antidepressants. We found that the treatment significantly increased the production of mBDNF, but decreased the production of truncated BDNF and proBDNF. These results support that antidepressants can promote proBDNF cleavage. Further studies are needed to clarify whether proBDNF cleavage plays a role in antidepressant mechanisms. Keywords: antidepressant, mature BDNF, neurotrophic effect, proBDNF cleavage 

Maximizing Selective Cleavages at Aspartic Acid and Proline Residues for the Identification of Intact Proteins

Science.gov (United States)

Foreman, David J.; Dziekonski, Eric T.; McLuckey, Scott A.

2018-04-01

A new approach for the identification of intact proteins has been developed that relies on the generation of relatively few abundant products from specific cleavage sites. This strategy is intended to complement standard approaches that seek to generate many fragments relatively non-selectively. Specifically, this strategy seeks to maximize selective cleavage at aspartic acid and proline residues via collisional activation of precursor ions formed via electrospray ionization (ESI) under denaturing conditions. A statistical analysis of the SWISS-PROT database was used to predict the number of arginine residues for a given intact protein mass and predict a m/z range where the protein carries a similar charge to the number of arginine residues thereby enhancing cleavage at aspartic acid residues by limiting proton mobility. Cleavage at aspartic acid residues is predicted to be most favorable in the m/z range of 1500-2500, a range higher than that normally generated by ESI at low pH. Gas-phase proton transfer ion/ion reactions are therefore used for precursor ion concentration from relatively high charge states followed by ion isolation and subsequent generation of precursor ions within the optimal m/z range via a second proton transfer reaction step. It is shown that the majority of product ion abundance is concentrated into cleavages C-terminal to aspartic acid residues and N-terminal to proline residues for ions generated by this process. Implementation of a scoring system that weights both ion fragment type and ion fragment area demonstrated identification of standard proteins, ranging in mass from 8.5 to 29.0 kDa. [Figure not available: see fulltext.

Quantification of DNA cleavage specificity in Hi-C experiments.

Science.gov (United States)

Meluzzi, Dario; Arya, Gaurav

2016-01-08

Hi-C experiments produce large numbers of DNA sequence read pairs that are typically analyzed to deduce genomewide interactions between arbitrary loci. A key step in these experiments is the cleavage of cross-linked chromatin with a restriction endonuclease. Although this cleavage should happen specifically at the enzyme's recognition sequence, an unknown proportion of cleavage events may involve other sequences, owing to the enzyme's star activity or to random DNA breakage. A quantitative estimation of these non-specific cleavages may enable simulating realistic Hi-C read pairs for validation of downstream analyses, monitoring the reproducibility of experimental conditions and investigating biophysical properties that correlate with DNA cleavage patterns. Here we describe a computational method for analyzing Hi-C read pairs to estimate the fractions of cleavages at different possible targets. The method relies on expressing an observed local target distribution downstream of aligned reads as a linear combination of known conditional local target distributions. We validated this method using Hi-C read pairs obtained by computer simulation. Application of the method to experimental Hi-C datasets from murine cells revealed interesting similarities and differences in patterns of cleavage across the various experiments considered. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Dataset of cocoa aspartic protease cleavage sites

Directory of Open Access Journals (Sweden)

Katharina Janek

2016-09-01

Full Text Available The data provide information in support of the research article, “The cleavage specificity of the aspartic protease of cocoa beans involved in the generation of the cocoa-specific aroma precursors” (Janek et al., 2016 [1]. Three different protein substrates were partially digested with the aspartic protease isolated from cocoa beans and commercial pepsin, respectively. The obtained peptide fragments were analyzed by matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF-MS/MS and identified using the MASCOT server. The N- and C-terminal ends of the peptide fragments were used to identify the corresponding in-vitro cleavage sites by comparison with the amino acid sequences of the substrate proteins. The same procedure was applied to identify the cleavage sites used by the cocoa aspartic protease during cocoa fermentation starting from the published amino acid sequences of oligopeptides isolated from fermented cocoa beans. Keywords: Aspartic protease, Cleavage sites, Cocoa, In-vitro proteolysis, Mass spectrometry, Peptides

Caspase-2 cleavage of tau reversibly impairs memory.

Science.gov (United States)

Zhao, Xiaohui; Kotilinek, Linda A; Smith, Benjamin; Hlynialuk, Chris; Zahs, Kathleen; Ramsden, Martin; Cleary, James; Ashe, Karen H

2016-11-01

In Alzheimer's disease (AD) and other tauopathies, the tau protein forms fibrils, which are believed to be neurotoxic. However, fibrillar tau has been dissociated from neuron death and network dysfunction, suggesting the involvement of nonfibrillar species. Here we describe a novel pathological process in which caspase-2 cleavage of tau at Asp314 impairs cognitive and synaptic function in animal and cellular models of tauopathies by promoting the missorting of tau to dendritic spines. The truncation product, Δtau314, resists fibrillation and is present at higher levels in brains from cognitively impaired mice and humans with AD. The expression of tau mutants that resisted caspase-2 cleavage prevented tau from infiltrating spines, dislocating glutamate receptors and impairing synaptic function in cultured neurons, and it prevented memory deficits and neurodegeneration in mice. Decreasing the levels of caspase-2 restored long-term memory in mice that had existing deficits. Our results suggest an overall treatment strategy for re-establishing synaptic function and restoring memory in patients with AD by preventing tau from accumulating in dendritic spines.

Cleavage events and sperm dynamics in chick intrauterine embryos.

Directory of Open Access Journals (Sweden)

Hyung Chul Lee

Full Text Available This study was undertaken to elucidate detailed event of early embryogenesis in chicken embryos using a noninvasive egg retrieval technique before oviposition. White Leghorn intrauterine eggs were retrieved from 95 cyclic hens aged up to 54-56 weeks and morphogenetic observation was made under both bright field and fluorescent image in a time course manner. Differing from mammals, asymmetric cleavage to yield preblastodermal cells was observed throughout early embryogenesis. The first two divisions occurred synchronously and four polarized preblastodermal cells resulted after cruciform cleavage. Then, asynchronous cleavage continued in a radial manner and overall cell size in the initial cleavage region was smaller than that in the distal area. Numerous sperms were visible, regardless of zygotic nuclei formation. Condensed sperm heads were present mainly in the perivitelline space and cytoplasm, and rarely in the yolk region, while decondensed sperm heads were only visible in the yolk. In conclusion, apparent differences in sperm dynamics and early cleavage events compared with mammalian embryos were detected in chick embryo development, which demonstrated polarized cleavage with penetrating supernumerary sperm into multiple regions.

In vivo analysis of the Notch receptor S1 cleavage.

Directory of Open Access Journals (Sweden)

Robert J Lake

2009-08-01

Full Text Available A ligand-independent cleavage (S1 in the extracellular domain of the mammalian Notch receptor results in what is considered to be the canonical heterodimeric form of Notch on the cell surface. The in vivo consequences and significance of this cleavage on Drosophila Notch signaling remain unclear and contradictory. We determined the cleavage site in Drosophila and examined its in vivo function by a transgenic analysis of receptors that cannot be cleaved. Our results demonstrate a correlation between loss of cleavage and loss of in vivo function of the Notch receptor, supporting the notion that S1 cleavage is an in vivo mechanism of Notch signal control.

Biotransformation of the high-molecular weight polycyclic aromatic hydrocarbon (PAH) benzo[k]fluoranthene by Sphingobium sp. strain KK22 and identification of new products of non-alternant PAH biodegradation by liquid chromatography electrospray ionization tandem mass spectrometry.

Science.gov (United States)

Maeda, Allyn H; Nishi, Shinro; Hatada, Yuji; Ozeki, Yasuhiro; Kanaly, Robert A

2014-03-01

A pathway for the biotransformation of the environmental pollutant and high-molecular weight polycyclic aromatic hydrocarbon (PAH) benzo[k]fluoranthene by a soil bacterium was constructed through analyses of results from liquid chromatography negative electrospray ionization tandem mass spectrometry (LC/ESI(-)-MS/MS). Exposure of Sphingobium sp. strain KK22 to benzo[k]fluoranthene resulted in transformation to four-, three- and two-aromatic ring products. The structurally similar four- and three-ring non-alternant PAHs fluoranthene and acenaphthylene were also biotransformed by strain KK22, and LC/ESI(-)-MS/MS analyses of these products confirmed the lower biotransformation pathway proposed for benzo[k]fluoranthene. In all, seven products from benzo[k]fluoranthene and seven products from fluoranthene were revealed and included previously unreported products from both PAHs. Benzo[k]fluoranthene biotransformation proceeded through ortho-cleavage of 8,9-dihydroxy-benzo[k]fluoranthene to 8-carboxyfluoranthenyl-9-propenic acid and 9-hydroxy-fluoranthene-8-carboxylic acid, and was followed by meta-cleavage to produce 3-(2-formylacenaphthylen-1-yl)-2-hydroxy-prop-2-enoic acid. The fluoranthene pathway converged with the benzo[k]fluoranthene pathway through detection of the three-ring product, 2-formylacenaphthylene-1-carboxylic acid. Production of key downstream metabolites, 1,8-naphthalic anhydride and 1-naphthoic acid from benzo[k]fluoranthene, fluoranthene and acenaphthylene biotransformations provided evidence for a common pathway by strain KK22 for all three PAHs through acenaphthoquinone. Quantitative analysis of benzo[k]fluoranthene biotransformation by strain KK22 confirmed biodegradation. This is the first pathway proposed for the biotransformation of benzo[k]fluoranthene by a bacterium. © 2013 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Biotransformation of the high-molecular weight polycyclic aromatic hydrocarbon (PAH) benzo[k]fluoranthene by Sphingobium sp. strain KK22 and identification of new products of non-alternant PAH biodegradation by liquid chromatography electrospray ionization tandem mass spectrometry

Science.gov (United States)

Maeda, Allyn H; Nishi, Shinro; Hatada, Yuji; Ozeki, Yasuhiro; Kanaly, Robert A

2014-01-01

A pathway for the biotransformation of the environmental pollutant and high-molecular weight polycyclic aromatic hydrocarbon (PAH) benzo[k]fluoranthene by a soil bacterium was constructed through analyses of results from liquid chromatography negative electrospray ionization tandem mass spectrometry (LC/ESI(–)-MS/MS). Exposure of Sphingobium sp. strain KK22 to benzo[k]fluoranthene resulted in transformation to four-, three-and two-aromatic ring products. The structurally similar four-and three-ring non-alternant PAHs fluoranthene and acenaphthylene were also biotransformed by strain KK22, and LC/ESI(–)-MS/MS analyses of these products confirmed the lower biotransformation pathway proposed for benzo[k]fluoranthene. In all, seven products from benzo[k]fluoranthene and seven products from fluoranthene were revealed and included previously unreported products from both PAHs. Benzo[k]fluoranthene biotransformation proceeded through ortho-cleavage of 8,9-dihydroxy-benzo[k]fluoranthene to 8-carboxyfluoranthenyl-9-propenic acid and 9-hydroxy-fluoranthene-8-carboxylic acid, and was followed by meta-cleavage to produce 3-(2-formylacenaphthylen-1-yl)-2-hydroxy-prop-2-enoic acid. The fluoranthene pathway converged with the benzo[k]fluoranthene pathway through detection of the three-ring product, 2-formylacenaphthylene-1-carboxylic acid. Production of key downstream metabolites, 1,8-naphthalic anhydride and 1-naphthoic acid from benzo[k]fluoranthene, fluoranthene and acenaphthylene biotransformations provided evidence for a common pathway by strain KK22 for all three PAHs through acenaphthoquinone. Quantitative analysis of benzo[k]fluoranthene biotransformation by strain KK22 confirmed biodegradation. This is the first pathway proposed for the biotransformation of benzo[k]fluoranthene by a bacterium. PMID:24325265

Seneca Valley Virus Suppresses Host Type I Interferon Production by Targeting Adaptor Proteins MAVS, TRIF, and TANK for Cleavage.

Science.gov (United States)

Qian, Suhong; Fan, Wenchun; Liu, Tingting; Wu, Mengge; Zhang, Huawei; Cui, Xiaofang; Zhou, Yun; Hu, Junjie; Wei, Shaozhong; Chen, Huanchun; Li, Xiangmin; Qian, Ping

2017-08-15

Seneca Valley virus (SVV) is an oncolytic RNA virus belonging to the Picornaviridae family. Its nucleotide sequence is highly similar to those of members of the Cardiovirus genus. SVV is also a neuroendocrine cancer-selective oncolytic picornavirus that can be used for anticancer therapy. However, the interaction between SVV and its host is yet to be fully characterized. In this study, SVV inhibited antiviral type I interferon (IFN) responses by targeting different host adaptors, including mitochondrial antiviral signaling (MAVS), Toll/interleukin 1 (IL-1) receptor domain-containing adaptor inducing IFN-β (TRIF), and TRAF family member-associated NF-κB activator (TANK), via viral 3C protease (3C pro ). SVV 3C pro mediated the cleavage of MAVS, TRIF, and TANK at specific sites, which required its protease activity. The cleaved MAVS, TRIF, and TANK lost the ability to regulate pattern recognition receptor (PRR)-mediated IFN production. The cleavage of TANK also facilitated TRAF6-induced NF-κB activation. SVV was also found to be sensitive to IFN-β. Therefore, SVV suppressed antiviral IFN production to escape host antiviral innate immune responses by cleaving host adaptor molecules. IMPORTANCE Host cells have developed various defenses against microbial pathogen infection. The production of IFN is the first line of defense against microbial infection. However, viruses have evolved many strategies to disrupt this host defense. SVV, a member of the Picornavirus genus, is an oncolytic virus that shows potential functions in anticancer therapy. It has been demonstrated that IFN can be used in anticancer therapy for certain tumors. However, the relationship between oncolytic virus and innate immune response in anticancer therapy is still not well known. In this study, we showed that SVV has evolved as an effective mechanism to inhibit host type I IFN production by using its 3C pro to cleave the molecules MAVS, TRIF, and TANK directly. These molecules are crucial for

Rings of continuous functions, symmetric products, and Frobenius algebras

International Nuclear Information System (INIS)

Buchstaber, Viktor M; Rees, E G

2004-01-01

A constructive proof is given for the classical theorem of Gel'fand and Kolmogorov (1939) characterising the image of the evaluation map from a compact Hausdorff space X into the linear space C(X)* dual to the ring C(X) of continuous functions on X. Our approach to the proof enabled us to obtain a more general result characterising the image of the evaluation map from the symmetric products Sym n (X) into C(X)*. A similar result holds if X=C m and leads to explicit equations for symmetric products of affine algebraic varieties as algebraic subvarieties in the linear space dual to the polynomial ring. This leads to a better understanding of the algebra of multisymmetric polynomials. The proof of all these results is based on a formula used by Frobenius in 1896 in defining higher characters of finite groups. This formula had no further applications for a long time; however, it has appeared in several independent contexts during the last fifteen years. It was used by A. Wiles and R.L. Taylor in studying representations and by H.-J. Hoehnke and K.W. Johnson and later by J. McKay in studying finite groups. It plays an important role in our work concerning multivalued groups. Several properties of this remarkable formula are described. It is also used to prove a theorem on the structure constants of Frobenius algebras, which have recently attracted attention due to constructions taken from topological field theory and singularity theory. This theorem develops a result of Hoehnke published in 1958. As a corollary, a direct self-contained proof is obtained for the fact that the 1-, 2-, and 3-characters of the regular representation determine a finite group up to isomorphism. This result was first published by Hoehnke and Johnson in 1992

Quantitative characterization of cleavage and hydrogen-assisted quasi-cleavage fracture surfaces with the use of confocal laser scanning microscopy

International Nuclear Information System (INIS)

Merson, E.; Kudrya, A.V.; Trachenko, V.A.; Merson, D.; Danilov, V.; Vinogradov, A.

2016-01-01

“True” cleavage (TC) and quasi-cleavage (QC) fracture surfaces of low-carbon steel specimens tested in liquid nitrogen and after hydrogen charging respectively were investigated by quantitative confocal laser scanning microscopy (CLSM) and conventional scanning electron microscopy (SEM) with electron-backscattered diffraction (EBSD). Topological and crystallographic features of the TC fracture surface are found in good agreement with the generally accepted cleavage mechanism: TC facets diameters correspond to those of grains; the crack path strictly follows the crystallographic orientation of grains and the most of the cleavage cracks are parallel to {100} planes. On the 2D SEM images, the QC facets appeared resembling the TC ones in terms of river line patterns, shapes and sizes. However, the substantial differences between the topography of these two kinds of fracture surfaces were revealed by 3D CLSM: the average misorientation angle between QC facets and the roughness of the QC fracture surface were much lower than those measured for TC. It is demonstrated that all these features are attributed to the specific fracture mechanism operating during hydrogen-assisted cracking.

Quantitative characterization of cleavage and hydrogen-assisted quasi-cleavage fracture surfaces with the use of confocal laser scanning microscopy

Energy Technology Data Exchange (ETDEWEB)

Merson, E. [Institute of Advanced Technologies, Togliatti State University, 445667 (Russian Federation); Kudrya, A.V.; Trachenko, V.A. [Department of Physical Metallurgy and the Physics of Strength, NUST MISiS, Moscow 119490 (Russian Federation); Merson, D. [Institute of Advanced Technologies, Togliatti State University, 445667 (Russian Federation); Laboratory for Advanced Materials, Kazan Federal University, Naberezhnye Chelny 423812, Republic of Tatarstan (Russian Federation); Danilov, V. [Institute of Advanced Technologies, Togliatti State University, 445667 (Russian Federation); Vinogradov, A. [Institute of Advanced Technologies, Togliatti State University, 445667 (Russian Federation); Department of Engineering Design and Materials, Norwegian University of Science and Technology – NTNU, N-7491 Trondheim (Norway)

2016-05-17

“True” cleavage (TC) and quasi-cleavage (QC) fracture surfaces of low-carbon steel specimens tested in liquid nitrogen and after hydrogen charging respectively were investigated by quantitative confocal laser scanning microscopy (CLSM) and conventional scanning electron microscopy (SEM) with electron-backscattered diffraction (EBSD). Topological and crystallographic features of the TC fracture surface are found in good agreement with the generally accepted cleavage mechanism: TC facets diameters correspond to those of grains; the crack path strictly follows the crystallographic orientation of grains and the most of the cleavage cracks are parallel to {100} planes. On the 2D SEM images, the QC facets appeared resembling the TC ones in terms of river line patterns, shapes and sizes. However, the substantial differences between the topography of these two kinds of fracture surfaces were revealed by 3D CLSM: the average misorientation angle between QC facets and the roughness of the QC fracture surface were much lower than those measured for TC. It is demonstrated that all these features are attributed to the specific fracture mechanism operating during hydrogen-assisted cracking.

Fermentation products of solvent tolerant marine bacterium Moraxella spp. MB1 and its biotechnological applications in salicylic acid bioconversion.

Directory of Open Access Journals (Sweden)

Solimabi Wahidullah

Full Text Available As part of a proactive approach to environmental protection, emerging issues with potential impact on the environment is the subject of ongoing investigation. One emerging area of environmental research concerns pharmaceuticals like salicylic acid, which is the main metabolite of various analgesics including aspirin. It is a common component of sewage effluent and also an intermediate in the degradation pathway of various aromatic compounds which are introduced in the marine environment as pollutants. In this study, biotransformation products of salicylic acid by seaweed, Bryopsis plumosa, associated marine bacterium, Moraxella spp. MB1, have been investigated. Phenol, conjugates of phenol and hydroxy cinnamic acid derivatives (coumaroyl, caffeoyl, feruloyl and trihydroxy cinnamyl with salicylic acid (3-8 were identified as the bioconversion products by electrospray ionization mass spectrometry. These results show that the microorganism do not degrade phenolic acid but catalyses oxygen dependent transformations without ring cleavage. The degradation of salicylic acid is known to proceed either via gentisic acid pathway or catechol pathway but this is the first report of biotransformation of salicylic acid into cinnamates, without ring cleavage. Besides cinnamic acid derivatives (9-12, metabolites produced by the bacterium include antimicrobial indole (13 and β-carbolines, norharman (14, harman (15 and methyl derivative (16, which are beneficial to the host and the environment.

Functional analysis of coordinated cleavage in V(D)J recombination.

Science.gov (United States)

Kim, D R; Oettinger, M A

1998-08-01

V(D)J recombination in vivo requires a pair of signals with distinct spacer elements of 12 and 23 bp that separate conserved heptamer and nonamer motifs. Cleavage in vitro by the RAG1 and RAG2 proteins can occur at individual signals when the reaction buffer contains Mn2+, but cleavage is restricted to substrates containing two signals when Mg2+ is the divalent cation. By using a novel V(D)J cleavage substrate, we show that while the RAG proteins alone establish a moderate preference for a 12/23 pair versus a 12/12 pair, a much stricter dependence of cleavage on the 12/23 signal pair is produced by the inclusion of HMG1 and competitor double-stranded DNA. The competitor DNA serves to inhibit the cleavage of substrates carrying a 12/12 or 23/23 pair, as well as the cutting at individual signals in 12/23 substrates. We show that a 23/33 pair is more efficiently recombined than a 12/33 pair, suggesting that the 12/23 rule can be generalized to a requirement for spacers that differ from each other by a single helical turn. Furthermore, we suggest that a fixed spatial orientation of signals is required for cleavage. In general, the same signal variants that can be cleaved singly can function under conditions in which a signal pair is required. However, a chemically modified substrate with one noncleavable signal enables us to show that formation of a functional cleavage complex is mechanistically separable from the cleavage reaction itself and that although cleavage requires a pair of signals, cutting does not have to occur simultaneously at both. The implications of these results are discussed with respect to the mechanism of V(D)J recombination and the generation of chromosomal translocations.

Di-µ-hydroxo Bridge Cleavage Reactions between [Co(nta)(µ-OH)] 2 ...

African Journals Online (AJOL)

NJD

2004-04-22

Apr 22, 2004 ... subsequent rate determining steps to form presumably a ligand-substituted, mono-bridged complex, [(nta)(OH)Co-µ-. OH-Co(nta)(L)]2– (L = py/dmap). The latter decomposes rapidly to form the products. The preferred pathway for these bridge cleavage seemed to be the reaction of the mono-µ-hydroxo-.

Photochemical Ring-Opening Reaction in 2(1H)-Pyrimidinones: A Matrix Isolation Study

OpenAIRE

Lapinski, Leszek; Rostkowska, Hanna; Khvorostov, Artem; Fausto, Rui; Nowak, Maciej J.

2003-01-01

Photoreactions induced by UV-B (290−320 nm) irradiation were studied for 1-methyl-2(1H)-pyrimidinone and 1-methylcytosine monomers isolated in low-temperature inert gas matrixes. A Norrish type I α-cleavage reaction leading to open-ring conjugated isocyanate was observed for 1-methyl-2(1H)-pyrimidinone. The structure of the photoproduct was identified by comparison of its experimental IR spectrum with the spectrum theoretically calculated at the DFT(B3LYP)/6-31++G(d,p) level. The main indicat...

Alkali metal control over N-N cleavage in iron complexes.

Science.gov (United States)

Grubel, Katarzyna; Brennessel, William W; Mercado, Brandon Q; Holland, Patrick L

2014-12-03

Though N2 cleavage on K-promoted Fe surfaces is important in the large-scale Haber-Bosch process, there is still ambiguity about the number of Fe atoms involved during the N-N cleaving step and the interactions responsible for the promoting ability of K. This work explores a molecular Fe system for N2 reduction, particularly focusing on the differences in the results obtained using different alkali metals as reductants (Na, K, Rb, Cs). The products of these reactions feature new types of Fe-N2 and Fe-nitride cores. Surprisingly, adding more equivalents of reductant to the system gives a product in which the N-N bond is not cleaved, indicating that the reducing power is not the most important factor that determines the extent of N2 activation. On the other hand, the results suggest that the size of the alkali metal cation can control the number of Fe atoms that can approach N2, which in turn controls the ability to achieve N2 cleavage. The accumulated results indicate that cleaving the triple N-N bond to nitrides is facilitated by simultaneous approach of least three low-valent Fe atoms to a single molecule of N2.

Essential role of cyclophilin A for hepatitis C virus replication and virus production and possible link to polyprotein cleavage kinetics.

Directory of Open Access Journals (Sweden)

Artur Kaul

2009-08-01

Full Text Available Viruses are obligate intracellular parasites and therefore their replication completely depends on host cell factors. In case of the hepatitis C virus (HCV, a positive-strand RNA virus that in the majority of infections establishes persistence, cyclophilins are considered to play an important role in RNA replication. Subsequent to the observation that cyclosporines, known to sequester cyclophilins by direct binding, profoundly block HCV replication in cultured human hepatoma cells, conflicting results were obtained as to the particular cyclophilin (Cyp required for viral RNA replication and the underlying possible mode of action. By using a set of cell lines with stable knock-down of CypA or CypB, we demonstrate in the present work that replication of subgenomic HCV replicons of different genotypes is reduced by CypA depletion up to 1,000-fold whereas knock-down of CypB had no effect. Inhibition of replication was rescued by over-expression of wild type CypA, but not by a mutant lacking isomerase activity. Replication of JFH1-derived full length genomes was even more sensitive to CypA depletion as compared to subgenomic replicons and virus production was completely blocked. These results argue that CypA may target an additional viral factor outside of the minimal replicase contributing to RNA amplification and assembly, presumably nonstructural protein 2. By selecting for resistance against the cyclosporine analogue DEBIO-025 that targets CypA in a dose-dependent manner, we identified two mutations (V2440A and V2440L close to the cleavage site between nonstructural protein 5A and the RNA-dependent RNA polymerase in nonstructural protein 5B that slow down cleavage kinetics at this site and reduce CypA dependence of viral replication. Further amino acid substitutions at the same cleavage site accelerating processing increase CypA dependence. Our results thus identify an unexpected correlation between HCV polyprotein processing and CypA dependence

Essential role of cyclophilin A for hepatitis C virus replication and virus production and possible link to polyprotein cleavage kinetics.

Science.gov (United States)

Kaul, Artur; Stauffer, Sarah; Berger, Carola; Pertel, Thomas; Schmitt, Jennifer; Kallis, Stephanie; Zayas, Margarita; Lopez, Margarita Zayas; Lohmann, Volker; Luban, Jeremy; Bartenschlager, Ralf

2009-08-01

Viruses are obligate intracellular parasites and therefore their replication completely depends on host cell factors. In case of the hepatitis C virus (HCV), a positive-strand RNA virus that in the majority of infections establishes persistence, cyclophilins are considered to play an important role in RNA replication. Subsequent to the observation that cyclosporines, known to sequester cyclophilins by direct binding, profoundly block HCV replication in cultured human hepatoma cells, conflicting results were obtained as to the particular cyclophilin (Cyp) required for viral RNA replication and the underlying possible mode of action. By using a set of cell lines with stable knock-down of CypA or CypB, we demonstrate in the present work that replication of subgenomic HCV replicons of different genotypes is reduced by CypA depletion up to 1,000-fold whereas knock-down of CypB had no effect. Inhibition of replication was rescued by over-expression of wild type CypA, but not by a mutant lacking isomerase activity. Replication of JFH1-derived full length genomes was even more sensitive to CypA depletion as compared to subgenomic replicons and virus production was completely blocked. These results argue that CypA may target an additional viral factor outside of the minimal replicase contributing to RNA amplification and assembly, presumably nonstructural protein 2. By selecting for resistance against the cyclosporine analogue DEBIO-025 that targets CypA in a dose-dependent manner, we identified two mutations (V2440A and V2440L) close to the cleavage site between nonstructural protein 5A and the RNA-dependent RNA polymerase in nonstructural protein 5B that slow down cleavage kinetics at this site and reduce CypA dependence of viral replication. Further amino acid substitutions at the same cleavage site accelerating processing increase CypA dependence. Our results thus identify an unexpected correlation between HCV polyprotein processing and CypA dependence of HCV

Cleavage specificity analysis of six type II transmembrane serine proteases (TTSPs using PICS with proteome-derived peptide libraries.

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Olivier Barré

Full Text Available Type II transmembrane serine proteases (TTSPs are a family of cell membrane tethered serine proteases with unclear roles as their cleavage site specificities and substrate degradomes have not been fully elucidated. Indeed just 52 cleavage sites are annotated in MEROPS, the database of proteases, their substrates and inhibitors.To profile the active site specificities of the TTSPs, we applied Proteomic Identification of protease Cleavage Sites (PICS. Human proteome-derived database searchable peptide libraries were assayed with six human TTSPs (matriptase, matriptase-2, matriptase-3, HAT, DESC and hepsin to simultaneously determine sequence preferences on the N-terminal non-prime (P and C-terminal prime (P' sides of the scissile bond. Prime-side cleavage products were isolated following biotinylation and identified by tandem mass spectrometry. The corresponding non-prime side sequences were derived from human proteome databases using bioinformatics. Sequencing of 2,405 individual cleaved peptides allowed for the development of the family consensus protease cleavage site specificity revealing a strong specificity for arginine in the P1 position and surprisingly a lysine in P1' position. TTSP cleavage between R↓K was confirmed using synthetic peptides. By parsing through known substrates and known structures of TTSP catalytic domains, and by modeling the remainder, structural explanations for this strong specificity were derived.Degradomics analysis of 2,405 cleavage sites revealed a similar and characteristic TTSP family specificity at the P1 and P1' positions for arginine and lysine in unfolded peptides. The prime side is important for cleavage specificity, thus making these proteases unusual within the tryptic-enzyme class that generally has overriding non-prime side specificity.

Mechanisms of Bond Cleavage during Manganese Oxide and UV Degradation of Glyphosate: Results from Phosphate Oxygen Isotopes and Molecular Simulations.

Science.gov (United States)

Jaisi, Deb P; Li, Hui; Wallace, Adam F; Paudel, Prajwal; Sun, Mingjing; Balakrishna, Avula; Lerch, Robert N

2016-11-16

Degradation of glyphosate in the presence of manganese oxide and UV light was analyzed using phosphate oxygen isotope ratios and density function theory (DFT). The preference of C-P or C-N bond cleavage was found to vary with changing glyphosate/manganese oxide ratios, indicating the potential role of sorption-induced conformational changes on the composition of intermediate degradation products. Isotope data confirmed that one oxygen atom derived solely from water was incorporated into the released phosphate during glyphosate degradation, and this might suggest similar nucleophilic substitution at P centers and C-P bond cleavage both in manganese oxide- and UV light-mediated degradation. The DFT results reveal that the C-P bond could be cleaved by water, OH - or • OH, with the energy barrier opposing bond dissociation being lowest in the presence of the radical species, and that C-N bond cleavage is favored by the formation of both nitrogen- and carbon-centered radicals. Overall, these results highlight the factors controlling the dominance of C-P or C-N bond cleavage that determines the composition of intermediate/final products and ultimately the degradation pathway.

Impaired Cleavage of Preproinsulin Signal Peptide Linked to Autosomal-Dominant Diabetes

Science.gov (United States)

Liu, Ming; Lara-Lemus, Roberto; Shan, Shu-ou; Wright, Jordan; Haataja, Leena; Barbetti, Fabrizio; Guo, Huan; Larkin, Dennis; Arvan, Peter

2012-01-01

Recently, missense mutations upstream of preproinsulin’s signal peptide (SP) cleavage site were reported to cause mutant INS gene-induced diabetes of youth (MIDY). Our objective was to understand the molecular pathogenesis using metabolic labeling and assays of proinsulin export and insulin and C-peptide production to examine the earliest events of insulin biosynthesis, highlighting molecular mechanisms underlying β-cell failure plus a novel strategy that might ameliorate the MIDY syndrome. We find that whereas preproinsulin-A(SP23)S is efficiently cleaved, producing authentic proinsulin and insulin, preproinsulin-A(SP24)D is inefficiently cleaved at an improper site, producing two subpopulations of molecules. Both show impaired oxidative folding and are retained in the endoplasmic reticulum (ER). Preproinsulin-A(SP24)D also blocks ER exit of coexpressed wild-type proinsulin, accounting for its dominant-negative behavior. Upon increased expression of ER–oxidoreductin-1, preproinsulin-A(SP24)D remains blocked but oxidative folding of wild-type proinsulin improves, accelerating its ER export and increasing wild-type insulin production. We conclude that the efficiency of SP cleavage is linked to the oxidation of (pre)proinsulin. In turn, impaired (pre)proinsulin oxidation affects ER export of the mutant as well as that of coexpressed wild-type proinsulin. Improving oxidative folding of wild-type proinsulin may provide a feasible way to rescue insulin production in patients with MIDY. PMID:22357960

Glycoside bond cleavage in the radiolysis of aqueous solutions of methylglycosides and disaccharides

International Nuclear Information System (INIS)

Shadyro, O.I.; Kisel', R.M.

2007-01-01

The kinetics of formation of methylglycoside and disaccharide radiolysis products resulting from the O-glycoside bond cleavage under the action of 137 Cs γ-radiation (0-2.5 kGy radiation doses, 0.28 Gy/s dose rate) was studied, and the yields of these products were determined. It was found that oxygen inhibits these processes. The findings suggest that the fragmentation reaction of C' 2 radicals plays an important role in the formation of carbohydrate degradation products in the radiolysis of aqueous carbohydrate solutions [ru

Cleavage sites within the poliovirus capsid protein precursors

International Nuclear Information System (INIS)

Larsen, G.R.; Anderson, C.W.; Dorner, A.J.; Semler, B.L.; Wimmer, E.

1982-01-01

Partial amino-terminal sequence analysis was performed on radiolabeled poliovirus capsid proteins VP1, VP2, and VP3. A computer-assisted comparison of the amino acid sequences obtained with that predicted by the nucleotide sequence of the poliovirus genome allows assignment of the amino terminus of each capsid protein to a unique position within the virus polyprotein. Sequence analysis of trypsin-digested VP4, which has a blocked amino terminus, demonstrates that VP4 is encoded at or very near to the amino terminus of the polyprotein. The gene order of the capsid proteins is VP4-VP2-VP3-VP1. Cleavage of VP0 to VP4 and VP2 is shown to occur between asparagine and serine, whereas the cleavages that separate VP2/VP3 and VP3/VP1 occur between glutamine and glycine residues. This finding supports the hypothesis that the cleavage of VP0, which occurs during virion morphogenesis, is distinct from the cleavages that separate functional regions of the polyprotein

Virtual Exploration of the Ring Systems Chemical Universe.

Science.gov (United States)

Visini, Ricardo; Arús-Pous, Josep; Awale, Mahendra; Reymond, Jean-Louis

2017-11-27

Here, we explore the chemical space of all virtually possible organic molecules focusing on ring systems, which represent the cyclic cores of organic molecules obtained by removing all acyclic bonds and converting all remaining atoms to carbon. This approach circumvents the combinatorial explosion encountered when enumerating the molecules themselves. We report the chemical universe database GDB4c containing 916 130 ring systems up to four saturated or aromatic rings and maximum ring size of 14 atoms and GDB4c3D containing the corresponding 6 555 929 stereoisomers. Almost all (98.6%) of these ring systems are unknown and represent chiral 3D-shaped macrocycles containing small rings and quaternary centers reminiscent of polycyclic natural products. We envision that GDB4c can serve to select new ring systems from which to design analogs of such natural products. The database is available for download at www.gdb.unibe.ch together with interactive visualization and search tools as a resource for molecular design.

A new cultural cleavage in post-modern society

Directory of Open Access Journals (Sweden)

Jan-Erik Lane

2007-09-01

Full Text Available The attitudes towards gender and homosexuality tend to be linked at the micro level (individuals, which explains the political saliency of this newly emerging cleavage. At the macro level (country, the main finding is that the value orientations towards gender and homosexuality are strongly embedded in the basic cultural or civilisation differences among countries. As developing countries modernise and enter post-modernity, they will also experience the gender cleavage, especially when they adhere to an individualistic culture. Cultural cleavages in the post-modern society, whether in rich or developing countries, can only be properly researched by the survey method. It opens up a large area for both micro and macro analyses in the social sciences.

Unexpected tolerance of alpha-cleavage of the prion protein to sequence variations.

Directory of Open Access Journals (Sweden)

José B Oliveira-Martins

Full Text Available The cellular form of the prion protein, PrP(C, undergoes extensive proteolysis at the alpha site (109K [see text]H110. Expression of non-cleavable PrP(C mutants in transgenic mice correlates with neurotoxicity, suggesting that alpha-cleavage is important for PrP(C physiology. To gain insights into the mechanisms of alpha-cleavage, we generated a library of PrP(C mutants with mutations in the region neighbouring the alpha-cleavage site. The prevalence of C1, the carboxy adduct of alpha-cleavage, was determined for each mutant. In cell lines of disparate origin, C1 prevalence was unaffected by variations in charge and hydrophobicity of the region neighbouring the alpha-cleavage site, and by substitutions of the residues in the palindrome that flanks this site. Instead, alpha-cleavage was size-dependently impaired by deletions within the domain 106-119. Almost no cleavage was observed upon full deletion of this domain. These results suggest that alpha-cleavage is executed by an alpha-PrPase whose activity, despite surprisingly limited sequence specificity, is dependent on the size of the central region of PrP(C.

Unusual reactions of diazocarbonyl compounds with α,β-unsaturated δ-amino esters: Rh(II-catalyzed Wolff rearrangement and oxidative cleavage of N–H-insertion products

Directory of Open Access Journals (Sweden)

Valerij A. Nikolaev

2016-08-01

Full Text Available Rh(II-сatalyzed reactions of aroyldiazomethanes, diazoketoesters and diazodiketones with α,β-unsaturated δ-aminoesters, in contrast to reactions of diazomalonates and other diazoesters, give rise to the Wolff rearrangement and/or oxidative cleavage of the initially formed N–H-insertion products. These oxidation processes are mediated by Rh(II catalysts possessing perfluorinated ligands. The formation of pyrrolidine structures, characteristic for catalytic reactions of diazoesters, was not observed in these processes at all.

Comparative and phylogenetic perspectives of the cleavage process in tailed amphibians.

Science.gov (United States)

Desnitskiy, Alexey G; Litvinchuk, Spartak N

2015-10-01

The order Caudata includes about 660 species and displays a variety of important developmental traits such as cleavage pattern and egg size. However, the cleavage process of tailed amphibians has never been analyzed within a phylogenetic framework. We use published data on the embryos of 36 species concerning the character of the third cleavage furrow (latitudinal, longitudinal or variable) and the magnitude of synchronous cleavage period (up to 3-4 synchronous cell divisions in the animal hemisphere or a considerably longer series of synchronous divisions followed by midblastula transition). Several species from basal caudate families Cryptobranchidae (Andrias davidianus and Cryptobranchus alleganiensis) and Hynobiidae (Onychodactylus japonicus) as well as several representatives from derived families Plethodontidae (Desmognathus fuscus and Ensatina eschscholtzii) and Proteidae (Necturus maculosus) are characterized by longitudinal furrows of the third cleavage and the loss of synchrony as early as the 8-cell stage. By contrast, many representatives of derived families Ambystomatidae and Salamandridae have latitudinal furrows of the third cleavage and extensive period of synchronous divisions. Our analysis of these ontogenetic characters mapped onto a phylogenetic tree shows that the cleavage pattern of large, yolky eggs with short series of synchronous divisions is an ancestral trait for the tailed amphibians, while the data on the orientation of third cleavage furrows seem to be ambiguous with respect to phylogeny. Nevertheless, the midblastula transition, which is characteristic of the model species Ambystoma mexicanum (Caudata) and Xenopus laevis (Anura), might have evolved convergently in these two amphibian orders.

Mechanisms for lymphocytic choriomeningitis virus glycoprotein cleavage, transport, and incorporation into virions

International Nuclear Information System (INIS)

Kunz, Stefan; Edelmann, Kurt H.; Torre, Juan-Carlos de la; Gorney, Robert; Oldstone, Michael B.A.

2003-01-01

The glycoprotein (GP) of lymphocytic choriomeningitis virus (LCMV) serves as virus attachment protein to its receptor on host cells and is a key determinant for cell tropism, pathogenesis, and epidemiology of the virus. The GP of LCMV is posttranslationally cleaved by the subtilase SKI-1/S1P into two subunits, the peripheral GP1, which is implicated in receptor binding, and the transmembrane GP2 that is structurally similar to the fusion active membrane proximal portions of the glycoproteins of other enveloped viruses. The present study shows that cleavage by SKI-1/S1P is not required for cell surface expression of LCMVGP on infected cells but is essential for its incorporation into virions and for the production of infectious virus particles. In absence of SKI-1/S1P cleavage, cell-to-cell propagation of the virus was markedly reduced. Further, proteolytic processing of LCMVGP depends on the presence of a cluster of basic amino acids at the C-terminus of the cytoplasmic domain of GP2, a structural motif that is conserved in Old World arenaviruses. The effect of the truncation of the cytoplasmic tail on cleavage suggests a structural interdependence between the cytoplasmic domain and the ectodomains of LCMVGP

The Saturnian rings

International Nuclear Information System (INIS)

Alfven, H.

1975-09-01

The structure of the Saturnian rings is traditionally believed to be due to resonances caused by Mimas (and possibly other satellites). It is shown that both theoretical and observational evidence rule out this interpretation. The increased observational accuracy on one hand and the increased understanding of the cosmogonic processes on the other makes it possible to explain the structure of the ring system as a product of condensation from a partially corotating plasma. In certain respects the agreement between theory and observations is about 1%. (Auth.)

Fast cleavage of phycocyanobilin from phycocyanin for use in food colouring.

Science.gov (United States)

Roda-Serrat, Maria Cinta; Christensen, Knud Villy; El-Houri, Rime Bahij; Fretté, Xavier; Christensen, Lars Porskjær

2018-02-01

Phycocyanins from cyanobacteria are possible sources for new natural blue colourants. Their chromophore, phycocyanobilin (PCB), was cleaved from the apoprotein by solvolysis in alcohols and alcoholic aqueous solutions. In all cases two PCB isomers were obtained, while different solvent adducts were formed upon the use of different reagents. The reaction is believed to take place via two competing pathways, a concerted E2 elimination and a S N 2 nucleophilic substitution. Three cleavage methods were compared in terms of yield and purity: conventional reflux, sealed vessel heated in an oil bath, and microwave assisted reaction. The sealed vessel method is a new approach for fast cleavage of PCB from phycocyanin and gave at 120°C the same yield within 30min compared to 16h by the conventional reflux method (P<0.05). In addition the sealed vessel method resulted in improved purity compared to the other methods. Microwave irradiation increased product degradation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Detection of nucleic acid sequences by invader-directed cleavage

Science.gov (United States)

Brow, Mary Ann D.; Hall, Jeff Steven Grotelueschen; Lyamichev, Victor; Olive, David Michael; Prudent, James Robert

1999-01-01

The present invention relates to means for the detection and characterization of nucleic acid sequences, as well as variations in nucleic acid sequences. The present invention also relates to methods for forming a nucleic acid cleavage structure on a target sequence and cleaving the nucleic acid cleavage structure in a site-specific manner. The 5' nuclease activity of a variety of enzymes is used to cleave the target-dependent cleavage structure, thereby indicating the presence of specific nucleic acid sequences or specific variations thereof. The present invention further relates to methods and devices for the separation of nucleic acid molecules based by charge.

On (m, n)-absorbing ideals of commutative rings

Indian Academy of Sciences (India)

with respect to various ring theoretic constructions and study (m, n)-absorbing ideals in several commutative rings. For example, in a Bézout ring or a Boolean ring, an ideal is an (m, n)-absorbing ideal if and only if it is an n-absorbing ideal, and in an almost. Dedekind domain every (m, n)-absorbing ideal is a product of at ...

Controllable laser thermal cleavage of sapphire wafers

Science.gov (United States)

Xu, Jiayu; Hu, Hong; Zhuang, Changhui; Ma, Guodong; Han, Junlong; Lei, Yulin

2018-03-01

Laser processing of substrates for light-emitting diodes (LEDs) offers advantages over other processing techniques and is therefore an active research area in both industrial and academic sectors. The processing of sapphire wafers is problematic because sapphire is a hard and brittle material. Semiconductor laser scribing processing suffers certain disadvantages that have yet to be overcome, thereby necessitating further investigation. In this work, a platform for controllable laser thermal cleavage was constructed. A sapphire LED wafer was modeled using the finite element method to simulate the thermal and stress distributions under different conditions. A guide groove cut by laser ablation before the cleavage process was observed to guide the crack extension and avoid deviation. The surface and cross section of sapphire wafers processed using controllable laser thermal cleavage were characterized by scanning electron microscopy and optical microscopy, and their morphology was compared to that of wafers processed using stealth dicing. The differences in luminous efficiency between substrates prepared using these two processing methods are explained.

Apple ring rot-responsive putative microRNAs revealed by high-throughput sequencing in Malus × domestica Borkh.

Science.gov (United States)

Yu, Xin-Yi; Du, Bei-Bei; Gao, Zhi-Hong; Zhang, Shi-Jie; Tu, Xu-Tong; Chen, Xiao-Yun; Zhang, Zhen; Qu, Shen-Chun

2014-08-01

MicroRNAs (miRNAs) are small non-coding RNAs, which silence target mRNA via cleavage or translational inhibition to function in regulating gene expression. MiRNAs act as important regulators of plant development and stress response. For understanding the role of miRNAs responsive to apple ring rot stress, we identified disease-responsive miRNAs using high-throughput sequencing in Malus × domestica Borkh.. Four small RNA libraries were constructed from two control strains in M. domestica, crabapple (CKHu) and Fuji Naga-fu No. 6 (CKFu), and two disease stress strains, crabapple (DSHu) and Fuji Naga-fu No. 6 (DSFu). A total of 59 miRNA families were identified and five miRNAs might be responsive to apple ring rot infection and validated via qRT-PCR. Furthermore, we predicted 76 target genes which were regulated by conserved miRNAs potentially. Our study demonstrated that miRNAs was responsive to apple ring rot infection and may have important implications on apple disease resistance.

Ternary iron(II) complex with an emissive imidazopyridine arm from Schiff base cyclizations and its oxidative DNA cleavage activity.

Science.gov (United States)

Mukherjee, Arindam; Dhar, Shanta; Nethaji, Munirathinam; Chakravarty, Akhil R

2005-01-21

The ternary iron(II) complex [Fe(L')(L")](PF6)3(1) as a synthetic model for the bleomycins, where L' and L" are formed from metal-mediated cyclizations of N,N'-(2-hydroxypropane-1,3-diyl)bis(pyridine-2-aldimine)(L), is synthesized and structurally characterized by X-ray crystallography. In the six-coordinate iron(ii) complex, ligands L' and L" show tetradentate and bidentate chelating modes of bonding. Ligand L' is formed from an intramolecular attack of the alcoholic OH group of L to one imine moiety leading to the formation of a stereochemically constrained five-membered ring. Ligand L" which is formed from an intermolecular reaction involving one imine moiety of L and pyridine-2-carbaldehyde has an emissive cationic imidazopyridine pendant arm. The complex binds to double-stranded DNA in the minor groove giving a Kapp value of 4.1 x 10(5) M(-1) and displays oxidative cleavage of supercoiled DNA in the presence of H2O2 following a hydroxyl radical pathway. The complex also shows photo-induced DNA cleavage activity on UV light exposure involving formation of singlet oxygen as the reactive species.

The Fine Structure of Herman Rings

DEFF Research Database (Denmark)

Fagella, Nuria; Henriksen, Christian

2017-01-01

We study the geometric structure of the boundary of Herman rings in a model family of Blaschke products of degree 3 (up to quasiconformal deformation). Shishikura’s quasiconformal surgery relates the Herman ring to the Siegel disk of a quadratic polynomial. By studying the regularity properties...

Aromatics saturation, opening and cleavage technology for middle distillates

Energy Technology Data Exchange (ETDEWEB)

Oballa, M.C.; Simanzhenkov, V.; Kim, G. [NOVA Chemicals Corp., Calgary, AB (Canada)

2009-07-01

In order to address environmental concerns, there is a need to develop technologies to reformulate or adjust the quality of transportation fuels. The purpose is to reduce the concentration of the compounds which negatively affect the air that people breathe. One of those targeted is the aromatics content of diesel, because high aromatics content results in low cetane number of diesel, as well as higher emission of particulate matter. Less conventional sources of hydrocarbon feedstock such as oil from oil sands and/or shale oil are being exploited in Alberta. These feeds contain multiple fused aromatic ring compounds. NOVA Chemicals would like to use these potentially abundant liquids as feed, but they must first be transformed into a more user friendly state. This paper discussed the development of a process technology that could saturate the aromatic rings, open up the saturated rings and cleave them to get smaller paraffinic molecules. The products then comprised of lower paraffins are suitable as feed to steam crackers for the production of ethylene and propylene, higher paraffins suitable for blending into gasoline and mono aromatic ring compounds which may be further treated through alkylation of benzene to ethylbenzene and dealkylation to styrene. The paper discussed the process steps and highlighted the catalysts. Research results were also shown. It was concluded that the critical technology gaps, as well as solutions, which would enable overcoming the challenges related to handling of aromatic bitumen feedstock, entail the development of two different catalysts, which are on two different technology platforms. 7 refs., 3 tabs., 5 figs.

Hemoglobin cleavage site-specificity of the Plasmodium falciparum cysteine proteases falcipain-2 and falcipain-3.

Directory of Open Access Journals (Sweden)

Shoba Subramanian

Full Text Available The Plasmodium falciparum cysteine proteases falcipain-2 and falcipain-3 degrade host hemoglobin to provide free amino acids for parasite protein synthesis. Hemoglobin hydrolysis has been described as an ordered process initiated by aspartic proteases, but cysteine protease inhibitors completely block the process, suggesting that cysteine proteases can also initiate hemoglobin hydrolysis. To characterize the specific roles of falcipains, we used three approaches. First, using random P(1 - P(4 amino acid substrate libraries, falcipain-2 and falcipain-3 demonstrated strong preference for cleavage sites with Leu at the P(2 position. Second, with overlapping peptides spanning alpha and beta globin and proteolysis-dependent (18O labeling, hydrolysis was seen at many cleavage sites. Third, with intact hemoglobin, numerous cleavage products were identified. Our results suggest that hemoglobin hydrolysis by malaria parasites is not a highly ordered process, but rather proceeds with rapid cleavage by falcipains at multiple sites. However, falcipain-2 and falcipain-3 show strong specificity for P(2 Leu in small peptide substrates, in agreement with the specificity in optimized small molecule inhibitors that was identified previously. These results are consistent with a principal role of falcipain-2 and falcipain-3 in the hydrolysis of hemoglobin by P. falciparum and with the possibility of developing small molecule inhibitors with optimized specificity as antimalarial agents.

Storage Rings

International Nuclear Information System (INIS)

Fischer, W.

2010-01-01

Storage rings are circular machines that store particle beams at a constant energy. Beams are stored in rings without acceleration for a number of reasons (Tab. 1). Storage rings are used in high-energy, nuclear, atomic, and molecular physics, as well as for experiments in chemistry, material and life sciences. Parameters for storage rings such as particle species, energy, beam intensity, beam size, and store time vary widely depending on the application. The beam must be injected into a storage ring but may not be extracted (Fig. 1). Accelerator rings such as synchrotrons are used as storage rings before and after acceleration. Particles stored in rings include electrons and positrons; muons; protons and anti-protons; neutrons; light and heavy, positive and negative, atomic ions of various charge states; molecular and cluster ions, and neutral polar molecules. Spin polarized beams of electrons, positrons, and protons were stored. The kinetic energy of the stored particles ranges from 10 -6 eV to 3.5 x 10 12 eV (LHC, 7 x 10 12 eV planned), the number of stored particles from one (ESR) to 1015 (ISR). To store beam in rings requires bending (dipoles) and transverse focusing (quadrupoles). Higher order multipoles are used to correct chromatic aberrations, to suppress instabilities, and to compensate for nonlinear field errors of dipoles and quadrupoles. Magnetic multipole functions can be combined in magnets. Beams are stored bunched with radio frequency systems, and unbunched. The magnetic lattice and radio frequency system are designed to ensure the stability of transverse and longitudinal motion. New technologies allow for better storage rings. With strong focusing the beam pipe dimensions became much smaller than previously possible. For a given circumference superconducting magnets make higher energies possible, and superconducting radio frequency systems allow for efficient replenishment of synchrotron radiation losses of large current electron or positron beams

Nitrile anion cyclization with epoxysilanes followed by Brook rearrangement/ring-opening of cyclopropane nitriles/alkylation.

Science.gov (United States)

Okugawa, Seigo; Masu, Hyuma; Yamaguchi, Kentaro; Takeda, Kei

2005-12-09

[reactions: see text] The reaction of delta-silyl-gamma,delta-epoxypentanenitrile derivatives 9-12 with a base and an alkylating agent affords (Z)-delta-siloxy-gamma,delta-unsaturated pentanenitrile derivatives via a tandem process that involves the formation of a cyclopropane derivative by epoxy nitrile cyclization followed by Brook rearrangement and an anion-induced cleavage of the cyclopropane ring. Exclusive formation of a (Z)-derivative from trans-epoxides is explained by the reaction pathway that involves a backside displacement of the epoxide by the alpha-nitrile carbanion and the O-Si bond formation followed by concerted processes involving Brook rearrangement and the anti-mode of eliminative ring fission of the cyclopropane from the rotamer 19. The fact that (E)-isomers are exclusively obtained from cis-epoxides and alpha-cyclopropyl-alpha-silylcarbinol derivative 26 provides experimental support for the proposed pathway.

Full Length Research Paper Curcumin induces cleavage of -catenin ...

African Journals Online (AJOL)

β-Catenin/Tcf-4 signaling pathway plays important roles in colorectal tumorigenesis. RT-PCR, western blotting and immunoprecipitation were used to study the effects of curcumin on β-catenin/Tcf-4 signaling pathway in HT-29 cells. Treatment of curcumin could induce cleavage of β-catenin and the cleavage could be ...

Thermal catalytic oxidation of octachloronaphthalene over anatase TiO2 nanomaterial and its hypothesized mechanism

Science.gov (United States)

Su, Guijin; Li, Qianqian; Lu, Huijie; Zhang, Lixia; Huang, Linyan; Yan, Li; Zheng, Minghui

2015-12-01

As an environmentally-green technology, thermal catalytic oxidation of octachloronaphthalene (CN-75) over anatase TiO2 nanomaterials was investigated at 300 °C. A wide range of oxidation intermediates, which were investigated using various techniques, could be of three types: naphthalene-ring, single-benzene-ring, and completely ring-opened products. Reactive oxygen species on anatase TiO2 surface, such as O2-• and O2-, contributed to oxidative degradation. Based on these findings, a novel oxidation degradation mechanism was proposed. The reaction at (101) surface of anatase TiO2 was used as a model. The naphthalene-ring oxidative products with chloronaphthols and hydroxyl-pentachloronaphthalene-dione, could be formed via attacking the carbon of naphthalene ring at one or more positions by nucleophilic O2-. Lateral cleavage of the naphthalene ring at different C1-C10 and C4-C9, C1-C2 and C4-C9, C1-C2 or and C3-C4 bond positions by electrophilic O2-• could occur. This will lead to the formation of tetrachlorophenol, tetrachloro-benzoic acid, tetrachloro-phthalaldehyde, and tetrachloro-acrolein-benzoic acid, partially with further transformation into tetrachlorobenzene-dihydrodiol and tetrachloro-salicylic acid. Unexpectedly, the symmetric half section of CN-75 could be completely remained with generating the intricate oxidative intermediates characteristically containing tetrachlorobenzene structure. Complete cleavage of naphthalene ring could produce the ring-opened products, such as formic and acetic acids.

Photooxidative cleavage of 4(1H)-quinolinones to 2-acylaminobenzoic acids and derivatives

Energy Technology Data Exchange (ETDEWEB)

Staskun, B. (University of the Witwatersrand, Johannesburg (South Africa). Dept. of Chemistry); Foote, C.S. (California Univ., Los Angeles (USA). Dept. of Chemistry)

1984-12-01

4(1H)-Quinolinones undergo oxidative cleavage to afford the corresponding 2-acylaminobenzoic acids when subjected to dye-sensitized photooxygenation in methanol-aqueous sodium hydroxide solution. The derived 2-aminobenzoic acid was the predominant product in certain instances. The reaction, with singlet oxygen suggested as the active species, provides an alternative methodology for access to nuclear- substituted anthranilic acids and derivatives.

Copper-Catalyzed Oxidative Reaction of β-Keto Sulfones with Alcohols via C-S Bond Cleavage: Reaction Development and Mechanism Study.

Science.gov (United States)

Du, Bingnan; Wang, Wenmin; Wang, Yang; Qi, Zhenghang; Tian, Jiaqi; Zhou, Jie; Wang, Xiaochen; Han, Jianlin; Ma, Jing; Pan, Yi

2018-02-16

A Cu-catalyzed cascade oxidative radical process of β-keto sulfones with alcohols has been achieved by using oxygen as an oxidant. In this reaction, β-keto sulfones were converted into sulfinate esters under the oxidative conditions via cleavage of C-S bond. Experimental and computational studies demonstrate that a new pathway is involved in this reaction, which proceeds through the formation of the key four-coordinated Cu II intermediate, O-O bond homolysis induced C-S bond cleavage and Cu-catalyzed esterification to form the final products. This reaction provides a new strategy to sulfonate esters and enriches the research content of C-S bond cleavage and transformations. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Affect of Presenilin Mutations on APP Cleavage; Insights into the Pathogenesis of FAD

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Nuomin eLi

2016-03-01

Full Text Available Alzheimer disease (AD is characterized by progressive memory loss, reduction in cognitive functions, and damage to the brain. The β-amyloid precursor protein can be sequentially cleaved by β- secretase and γ-secretase. Mutations in the presenilin1（PS1） are the most common cause of Familial Alzheimer’s disease ( FAD. PS1 mutations can alter the activity of γ-secretase on the cleavage of the β-amyloid precursor protein, causing increased Aβ production. Previous studies show that the βAPP-C-terminal fragment is first cleaved by β-scretase, primarily generating long fragments of Aβ48 and Aβ49, followed by the stepwise cleavage of every three amino acid residues at the C terminus, resulting in Aβ48-, 45-, 42 line and Aβ49-, 46-, 43-, 40 line. Here, we used LC-MS/MS to analyze unique peptides IAT, VVIA, ITL，TVI，IVI through sequential cleavage, combined with ELISA to test the level of Aβ42 and Aβ40 for validation. The results show that most FAD mutant PS1 can alter the level of Aβ42 and Aβ40 monitored by the Aβ42/Aβ40 ratio. Among them, 6 mutants (I143T, H163P, S170F, Q223R, M233V and G384A affect the Aβ42/40 ratio through both Aβ49-40 and Aβ48-38 lines; L166P through decreasing the Aβ49-40 line, 6 mutants (I143V, M146V, G217A, E280A, L381V and L392V through increasing the Aβ48-42 line. More importantly, we found some mutations can affect the γ-secretase cleavage preference of α-CTF and β-CTF. In conclusion, we found that the FAD PS1 mutations mainly increase the generation of Aβ42 by decreasing the cleavage of Aβ42-Aβ38 and Aβ43-Aβ40.

Study of hydroxylation of benzene and toluene using a micro-DBD plasma reactor

International Nuclear Information System (INIS)

Sekiguchi, H; Ando, M; Kojima, H

2005-01-01

The hydroxylation behaviour of benzene and toluene were studied using a micro-plasma reactor, where an atmospheric non-thermal plasma was generated by a dielectric barrier discharge (DBD). The results indicated that oxidation products primarily consisted of phenol and C 4 -compounds for benzene hydroxylation, whereas cresol, benzaldehyde, benzylalcohol and C 4 -compounds were detected for toluene hydroxylation. By taking into consideration the reaction mechanism in the plasma reactor, these products were classified into (1) oxidation of the aromatic ring and functional group on the ring and (2) cleavage of the aromatic ring or dissociation of the functional group on the ring

Altered cleavage patterns in human tripronuclear embryos and their association to fertilization method

DEFF Research Database (Denmark)

Joergensen, Mette Warming; Agerholm, Inge; Hindkjaer, Johnny

2014-01-01

PURPOSE: To analyze the cleavage patterns in dipronuclear (2PN) and tripronuclear (3PN) embryos in relation to fertilization method. METHOD: Time-lapse analysis. RESULTS: Compared to 2PN, more 3PN IVF embryos displayed early cleavage into 3 cells (p ... stage (p embryos, the 2nd and 3rd cleavage cycles were completed within the expected time frame. However, timing of the cell divisions within the cleavage cycles differed between the two groups. In contrast......, the completion of the 1st, 2nd, and 3rd cleavage cycle was delayed, but with a similar division pattern for 3PN ICSI compared with the 2PN ICSI embryos. 3PN, more often than 2PN ICSI embryos, displayed early cleavage into 3 cells (p = 0.03) and arrested development from the compaction stage and onwards (p = 0...

Using Ring Strain to Control 4π-Electrocyclization Reactions: Torquoselectivity in Ring Closing of Medium-Ring Dienes and Ring Opening of Bicyclic Cyclobutenes.

Science.gov (United States)

Boon, Byron A; Green, Aaron G; Liu, Peng; Houk, K N; Merlic, Craig A

2017-05-05

Syntheses of strained cyclic dienes were accomplished via palladium(II)-catalyzed oxidative cyclizations of terminal bis(vinylboronate esters). The reactions generate strained (E,E)-1,3-dienes that undergo spontaneous 4π-electrocyclizations to form bicyclic cyclobutenes. Formation of the cyclobutenes is driven by the strain in the medium-ring (E,E)-1,3-diene intermediate. Thermal ring openings of the cyclobutenes give (Z,Z)-1,3-diene products, again for thermodynamic reasons. DFT calculations verified the thermodynamic versus kinetic control of the reactions, and kinetic studies are in excellent agreement with the calculated energy changes. An extension of the tandem coupling/4π-electrocyclization pathway was demonstrated by a palladium(II)-catalyzed oxidative homocoupling/8π-electrocyclization cascade.

RecA-mediated cleavage reaction of Lambda repressor and DNA ...

African Journals Online (AJOL)

PRECIOUS

2010-01-11

Jan 11, 2010 ... hydrolyze ATP at all, but fulfills RecA functions such as cleavage of Lambda repressor and strand .... DNA binding properties of RecA and may result in an in- .... AMP-PNP there is no cleavage of Lambda repressor (Figure.

Study of reactional conditions of oxidative cleavage reaction of bicyclic {beta}-hydroxy ethers promoted by ruthenium tetroxide; Estudo das condicoes reacionais da reacao de clivagem oxidativa de {beta}-hidroxi eteres biciclicos promovida por tetroxido de rutenio

Energy Technology Data Exchange (ETDEWEB)

Ferraz, Helena M.C.; Scalfo, Alexsandra C. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica; Vilalba, Bruno T.; Longo Junior, Luiz S., E-mail: luiz.longo@unifesp.b [Universidade Federal de Sao Paulo (UNIFESP-EPM), Diadema, SP (Brazil)

2010-07-01

A systematic study of the reaction of {beta}-hydroxy ethers with ruthenium tetraoxide (RuO{sub 4}), generated in situ from ruthenium trichloride and sodium periodate, is presented, leading to nine-membered ring keto-lactones in moderate yields. Three different solvent systems - AcOEt/MeCN/H{sub 2}O, MeCN/H{sub 2}O and DMC/H{sub 2}O - were studied leading to the desired products in lower yields than those obtained with the classical mixture of CCl{sub 4}/MeCN/H{sub 2}O, commonly used in reactions promoted by this oxidant. However, it is noteworthy that these new solvent systems represent greener alternatives to the chlorinated solvents used in the oxidative cleavage of {beta}-hydroxy ethers by RuO{sub 4}. (author)

Acquisition of a novel eleven amino acid insertion directly N-terminal to a tetrabasic cleavage site confers intracellular cleavage of an H7N7 influenza virus hemagglutinin

International Nuclear Information System (INIS)

Hamilton, Brian S.; Sun, Xiangjie; Chung, Changik; Whittaker, Gary R.

2012-01-01

A critical feature of highly pathogenic avian influenza viruses (H5N1 and H7N7) is the efficient intracellular cleavage of the hemagglutinin (HA) protein. H7N7 viruses also exist in equine species, and a unique feature of the equine H7N7 HA is the presence of an eleven amino acid insertion directly N-terminal to a tetrabasic cleavage site. Here, we show that three histidine residues within the unique insertion of the equine H7N7 HA are essential for intracellular cleavage. An asparagine residue within the insertion-derived glycosylation site was also found to be essential for intracellular cleavage. The presence of the histidine residues also appear to be involved in triggering fusion, since mutation of the histidine residues resulted in a destabilizing effect. Importantly, the addition of a tetrabasic site and the eleven amino acid insertion conferred efficient intracellular cleavage to the HA of an H7N3 low pathogenicity avian influenza virus. Our studies show that acquisition of the eleven amino acid insertion offers an alternative mechanism for intracellular cleavage of influenza HA.

Acquisition of a novel eleven amino acid insertion directly N-terminal to a tetrabasic cleavage site confers intracellular cleavage of an H7N7 influenza virus hemagglutinin

Energy Technology Data Exchange (ETDEWEB)

Hamilton, Brian S.; Sun, Xiangjie; Chung, Changik [Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca NY 14853 (United States); New York Center of Excellence for Influenza Research and Surveillance, University of Rochester Medical Center, Rochester NY 14627 (United States); Whittaker, Gary R., E-mail: grw7@cornell.edu [Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca NY 14853 (United States); New York Center of Excellence for Influenza Research and Surveillance, University of Rochester Medical Center, Rochester NY 14627 (United States)

2012-12-05

A critical feature of highly pathogenic avian influenza viruses (H5N1 and H7N7) is the efficient intracellular cleavage of the hemagglutinin (HA) protein. H7N7 viruses also exist in equine species, and a unique feature of the equine H7N7 HA is the presence of an eleven amino acid insertion directly N-terminal to a tetrabasic cleavage site. Here, we show that three histidine residues within the unique insertion of the equine H7N7 HA are essential for intracellular cleavage. An asparagine residue within the insertion-derived glycosylation site was also found to be essential for intracellular cleavage. The presence of the histidine residues also appear to be involved in triggering fusion, since mutation of the histidine residues resulted in a destabilizing effect. Importantly, the addition of a tetrabasic site and the eleven amino acid insertion conferred efficient intracellular cleavage to the HA of an H7N3 low pathogenicity avian influenza virus. Our studies show that acquisition of the eleven amino acid insertion offers an alternative mechanism for intracellular cleavage of influenza HA.

RecA-mediated cleavage activates UmuD for mutagenesis: Mechanistic relationship between transcriptional derepression and posttranslational activation

International Nuclear Information System (INIS)

Nohmi, Takehiko; Battista, J.R.; Dodson, L.A.; Walker, G.C.

1988-01-01

The products of the SOS-regulated umuDC operon are required for most UV and chemical mutagenesis in Escherichia coli. It has been shown that the UmuD protein shares homology with LexA, the repressor of the SOS genes. In this paper the authors describe a series of genetic experiments that indicate that the purpose of RecA-mediated cleavage of UmuD at its bond between Cys-24 and Gly-25 is to activate UmuD for its role in mutagenesis and that the COOH-terminal fragment of UmuD is necessary and sufficient for the role of UmuD in UV mutagenesis. Other genetic experiments are presented that (i) support the hypothesis that the primary role of Ser-60 in UmuD function is to act as a nucleophile in the RecA-mediated cleavage reaction and (ii) raise the possibility that RecA has a third role in UV mutagenesis besides mediating the cleavage of LexA and UmuD

Targeted cleavage of hepatitis E virus 3' end RNA mediated by hammerhead ribozymes inhibits viral RNA replication

International Nuclear Information System (INIS)

Sriram, Bandi; Thakral, Deepshi; Panda, Subrat Kumar

2003-01-01

The 3' end of hepatitis E virus (HEV) contains cis-acting regulatory element, which plays an important role in viral replication. To develop specific replication inhibitor at the molecular level, mono- and di-hammerhead ribozymes (Rz) were designed and synthesized against the conserved 3' end sequences of HEV, which cleave at nucleotide positions 7125 and 7112/7125, respectively. Di-hammerhead ribozyme with two catalytic motifs in tandem was designed to cleave simultaneously at two sites spaced 13 nucleotides apart, which increases the overall cleavage efficiency and prevents the development of escape mutants. Specific cleavage products were obtained with both the ribozymes in vitro at physiological conditions. The inactive control ribozymes showed no cleavage. The ribozymes showed specific inhibition of HEV 3' end fused-luciferase reporter gene expression by ∼37 and ∼60%, respectively in HepG2 cells. These results demonstrate a feasible approach to inhibit the HEV replication to a limited extent by targeting the cis-acting 3' end of HEV with hammerhead ribozymes

The structure of a complex of the lactonohydrolase zearalenone hydrolase with the hydrolysis product of zearalenone at 1.60 Å resolution.

Science.gov (United States)

Qi, Qi; Yang, Wen Jing; Zhou, Hu Jian; Ming, Deng Ming; Sun, Kai Lei; Xu, Tian Yu; Hu, Xiao Jian; Lv, Hong

2017-07-01

Zearalenone hydrolase (ZHD) is an α/β-hydrolase that detoxifies and degrades the lactone zearalenone (ZEN), a naturally occurring oestrogenic mycotoxin that contaminates crops. Several apoenzyme and enzyme-substrate complex structures have been reported in the resolution range 2.4-2.6 Å. However, the properties and mechanism of this enzyme are not yet fully understood. Here, a 1.60 Å resolution structure of a ZHD-product complex is reported which was determined from a C-terminally His 6 -tagged ZHD crystal soaked with 2 mM ZEN for 30 min. It shows that after the lactone-bond cleavage, the phenol-ring region moves closer to residues Leu132, Tyr187 and Pro188, while the lactone-ring region barely moves. Comparisons of the ZHD-substrate and ZHD-product structures show that the hydrophilic interactions change, especially Trp183 N ℇ1 , which shifts from contacting O2 to O12', suggesting that Trp183 is responsible for the unidirectional translational movement of the phenol ring. This structure provides information on the final stage of the catalytic mechanism of zearalenone hydrolysis.

Short RNA guides cleavage by eukaryotic RNase III.

Directory of Open Access Journals (Sweden)

Bruno Lamontagne

Full Text Available In eukaryotes, short RNAs guide a variety of enzymatic activities that range from RNA editing to translation repression. It is hypothesized that pre-existing proteins evolved to bind and use guide RNA during evolution. However, the capacity of modern proteins to adopt new RNA guides has never been demonstrated. Here we show that Rnt1p, the yeast orthologue of the bacterial dsRNA-specific RNase III, can bind short RNA transcripts and use them as guides for sequence-specific cleavage. Target cleavage occurred at a constant distance from the Rnt1p binding site, leaving the guide RNA intact for subsequent cleavage. Our results indicate that RNase III may trigger sequence-specific RNA degradation independent of the RNAi machinery, and they open the road for a new generation of precise RNA silencing tools that do not trigger a dsRNA-mediated immune response.

Kallistatin Ameliorates Influenza Virus Pathogenesis by Inhibition of Kallikrein-Related Peptidase 1-Mediated Cleavage of Viral Hemagglutinin

Science.gov (United States)

Leu, Chia-Hsing; Yang, Mei-Lin; Chung, Nai-Hui; Huang, Yen-Jang; Su, Yu-Chu; Chen, Yi-Cheng; Lin, Chia-Cheng; Shieh, Gia-Shing; Chang, Meng-Ya; Wang, Shainn-Wei; Chang, Yao; Chao, Julie; Chao, Lee

2015-01-01

Proteolytic cleavage of the hemagglutinin (HA) of influenza virus by host trypsin-like proteases is required for viral infectivity. Some serine proteases are capable of cleaving influenza virus HA, whereas some serine protease inhibitors (serpins) inhibit the HA cleavage in various cell types. Kallikrein-related peptidase 1 (KLK1, also known as tissue kallikrein) is a widely distributed serine protease. Kallistatin, a serpin synthesized mainly in the liver and rapidly secreted into the circulation, forms complexes with KLK1 and inhibits its activity. Here, we investigated the roles of KLK1 and kallistatin in influenza virus infection. We show that the levels of KLK1 increased, whereas those of kallistatin decreased, in the lungs of mice during influenza virus infection. KLK1 cleaved H1, H2, and H3 HA molecules and consequently enhanced viral production. In contrast, kallistatin inhibited KLK1-mediated HA cleavage and reduced viral production. Cells transduced with the kallistatin gene secreted kallistatin extracellularly, which rendered them more resistant to influenza virus infection. Furthermore, lentivirus-mediated kallistatin gene delivery protected mice against lethal influenza virus challenge by reducing the viral load, inflammation, and injury in the lung. Taking the data together, we determined that KLK1 and kallistatin contribute to the pathogenesis of influenza virus by affecting the cleavage of the HA peptide and inflammatory responses. This study provides a proof of principle for the potential therapeutic application of kallistatin or other KLK1 inhibitors for influenza. Since proteolytic activation also enhances the infectivity of some other viruses, kallistatin and other kallikrein inhibitors may be explored as antiviral agents against these viruses. PMID:26149981

Inclusive measurements of hyperon production at the CERN Intersecting Storage Rings

International Nuclear Information System (INIS)

Erhan, S.

1979-01-01

Measurements have been made of the inclusive reactions: pp→LAMBDA 0 +x, and pp→anti LAMBDA 0 +x, pp→exactly equal to - +x, pp→SIGMA+-(1385)+x) at equivalent laboratory moments of 1500 GeV/c (√s=53 GeV) and 2100 GeV/c (√s=62 GeV) at the CERN Intersecting Storage Rings (ISR). An estimate of the total LAMBDA 0 and anti LAMBDA 0 inclusive cross sections is presented. The measured data are extrapolated to x = 0 using √s = 44 GeV CERN Intersecting Storage Ring results. The cross sections for LAMBDA 0 and anti LAMBDA 0 are found to be 4.42 +- 0.18 mb and 1.17 +- 0.40 mb at 1500 GeV/c and 4.72 +- 0.18 mb. and 1.37 +- 0.48 mb at 2100 GeV/c respectively. The total exactly equal to - inclusive cross section in the region x > 0.4 is found to be. In addition, results are presented of searches for reactions: pp →(LAMBDA 0 anti LAMBDA 0 ) +x and pp→(LAMBDA 0 LAMBDA 0 )+x. Pair production of LAMBDA 0 anti LAMBDA 0 with x > 0.6 is measured to be 1.7 +-/0.2μb, while LAMBDA 0 LAMBDA 0 cross section in the same x range is less than 1.0 +- 0.1 μb

Molecular mechanism of the intramembrane cleavage of the β-carboxyl terminal fragment of amyloid precursor protein by γ-secretase

Directory of Open Access Journals (Sweden)

Maho eMorishima-Kawashima

2014-11-01

Full Text Available Amyloid β-protein (Aβ plays a central role in the pathogenesis of Alzheimer’s disease, the most common age-associated neurodegenerative disorder. Aβ is generated through intramembrane proteolysis of the β-carboxyl terminal fragment (βCTF of β-amyloid precursor protein (APP by γ-secretase. The initial cleavage by γ-secretase occurs in the membrane/cytoplasm boundary of the βCTF, liberating the APP intracellular domain (AICD. The remaining βCTFs, which are truncated at the C-terminus (longer Aβs, are then cropped sequentially in a stepwise manner, predominantly at three residue intervals, to generate Aβ. There are two major Aβ product lines which generate Aβ40 and Aβ42 with concomitant release of three and two tripeptides, respectively. Additionally, many alternative cleavages occur, releasing peptides with three to six residues. These modulate the Aβ product lines and define the species and quantity of Aβ generated. Here, we review our current understanding of the intramembrane cleavage of the βCTF by γ-secretase, which may contribute to the future goal of developing an efficient therapeutic strategy for Alzheimer’s disease.

Degradation of aromatic compounds in plants grown under aseptic conditions

Energy Technology Data Exchange (ETDEWEB)

Mithaishvili, T.; Ugrekhelidze, D.; Tsereteli, B.; Sadunishvili, T.; Kvesitadze, G. [Durmishidze Inst. of Biochemistry and Biotechnology, Academy of Sciences of Georgia, Tbilisi (Georgia); Scalla, R. [Lab. des Xenobiotiques, INRA, Toulouse (France)

2005-02-01

The aim of the work is to investigate the ability of higher plants to absorb and detoxify environmental pollutants - aromatic compounds via aromatic ring cleavage. Transformation of {sup 14}C specifically labelled benzene derivatives, [1-6-{sup 14}C]-nitrobenzene, [1-6-{sup 14}C]-aniline, [1-{sup 14}C]- and [7-{sup 14}C]-benzoic acid, in axenic seedlings of maize (Zea mays L.), kidney bean (Phaseolus vulgaris L.), pea (Pisum sativum L.) and pumpkin (Cucurbita pepo L.) were studied. After penetration in plants, the above xenobiotics are transformed by oxidative or reductive reactions, conjugation with cell endogenous compounds, and binding to biopolymers. The initial stage of oxidative degradation consists in hydroxylation reactions. The aromatic ring can then be cleaved and degraded into organic acids of the Krebs cycle. Ring cleavage is accompanied by {sup 14}CO{sub 2} evolution. Aromatic ring cleavage in plants has thus been demonstrated for different xenobiotics carrying different substitutions on their benzene ring. Conjugation with low molecular peptides is the main pathway of aromatic xenobiotics detoxification. Peptide conjugates are formed both by the initial xenobiotics (except nitrobenzene) and by intermediate transformation products. The chemical nature of the radioactive fragment and the amino acid composition of peptides participating in conjugation were identified. (orig.)

Unconjugated Bilirubin Inhibits Proteolytic Cleavage of von Willebrand Factor by ADAMTS13 Protease

Science.gov (United States)

Lu, Rui-Nan; Yang, Shangbin; Wu, Haifeng M.; Zheng, X. Long

2015-01-01

Summary Background Bilirubin is a yellow breakdown product of heme catabolism. Increased serum levels of unconjugated bilirubin are conditions commonly seen in premature neonates and adults with acute hemolysis including thrombotic microangiopathy. Previous studies have shown that unconjugated bilirubin lowers plasma ADAMTS13 activity, but the mechanism is not fully understood. Objectives The study is to determine whether unconjugated bilirubin directly inhibits the cleavage of von Willebrand factor (VWF) and its analogs by ADAMTS13. Methods Fluorogenic, SELDI-TOF mass spectrometric assay, and Western blotting analyses were employed to address this question. Results Unconjugated bilirubin inhibits the cleavage of F485-rVWF73-H, D633-rVWF73-H, and GST-rVWF71-11K by ADAMTS13 in a concentration-dependent manner with a half-maximal inhibitory concentration (IC50) of ~13 μM, ~70 μM, and ~17 μM, respectively. Unconjugated bilirubin also dose-dependently inhibits the cleavage of multimeric VWF by ADAMTS13 under denaturing conditions. The inhibitory activity of bilirubin on the cleavage of D633-rVWF73-H and multimeric VWF, but not F485-rVWF73-H, was eliminated after incubation with bilirubin oxidase that converts bilirubin to biliverdin. Furthermore, plasma ADAMTS13 activity in patients with hyperbilirubinemia is lower prior to than after treatment with bilirubin oxidase. Conclusions unconjugated bilirubin directly inhibits ADAMTS13’s ability to cleave both peptidyl and native VWF substrates in addition to its interference with certain fluorogenic assays. Our findings may help proper interpretation of ADAMTS13 results under pathological conditions. Whether elevated serum unconjugated bilirubin has an adverse effect in vivo remains to be determined in our future study. PMID:25782102

Effect of microstructure on the cleavage fracture strength of low carbon Mn-Ni-Mo bainitic steels

International Nuclear Information System (INIS)

Im, Young-Roc; Lee, Byeong-Joo; Oh, Yong Jun; Hong, Jun Hwa; Lee, Hu-Chul

2004-01-01

The effects of the microstructure on the cleavage fracture strength of low carbon Mn-Ni-Mo bainitic steels were examined. A four-point bend test and double-notched bend specimens were used to measure the cleavage fracture strength of the alloys and identify the cleavage initiating micro-cracks, respectively. The cleavage fracture strength and DBTT of Mn-Ni-Mo bainitic steels were strongly affected by the alloy carbon content. The decrease in the alloy carbon content resulted in a decrease in the inter-lath cementite-crowded layers and higher cleavage fracture strength. Micro-cracks that formed across the inter-lath cementite-crowded layers were observed to initiate cleavage fracture. The width of these inter-lath cementite-crowded layers was accepted as a cleavage initiating micro-crack size in the micro-mechanical modeling of the cleavage fracture, and the measured cleavage strength values of the bainitic Mn-Ni-Mo steels were well represented by the modified Griffith relationship

Purification, crystallization and X-ray diffraction analysis of a novel ring-cleaving enzyme (BoxCC) from Burkholderia xenovorans LB400

International Nuclear Information System (INIS)

Bains, Jasleen; Boulanger, Martin J.

2008-01-01

Preliminary X-ray diffraction studies of a novel ring-cleaving enzyme from B. xenovorans LB400 encoded by the benzoate-oxidation (box) pathway. The assimilation of aromatic compounds by microbial species requires specialized enzymes to cleave the thermodynamically stable ring. In the recently discovered benzoate-oxidation (box) pathway in Burkholderia xenovorans LB400, this is accomplished by a novel dihydrodiol lyase (BoxC C ). Sequence analysis suggests that BoxC C is part of the crotonase superfamily but includes an additional uncharacterized region of approximately 115 residues that is predicted to mediate ring cleavage. Processing of X-ray diffraction data to 1.5 Å resolution revealed that BoxC C crystallized with two molecules in the asymmetric unit of the P2 1 2 1 2 1 space group, with a solvent content of 47% and a Matthews coefficient of 2.32 Å 3 Da −1 . Selenomethionine BoxC C has been purified and crystals are currently being refined for anomalous dispersion studies

Ring opening of epoxides with C-nucleophiles.

Science.gov (United States)

Faiz, Sadia; Zahoor, Ameer Fawad

2016-11-01

Ring opening of epoxides has been an area of interest for organic chemists, owing to their reactivity toward nucleophiles. Such reactions yield important products depending on the type of nucleophiles used. This review article covers the synthetic approaches (1991-2015) used for the ring opening of epoxides via carbon nucleophiles.

Seco-B-Ring Steroidal Dienynes with Aromatic D Ring: Design, Synthesis and Biological Evaluation

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Marcin Szybinski

2017-10-01

Full Text Available Continuing our structure-activity studies on the vitamin D analogs with the altered intercyclic seco-B-ring fragment, we designed compounds possessing dienyne system conjugated with the benzene D ring. Analysis of the literature data and the docking experiments seemed to indicate that the target compounds could mimic the ligands with a good affinity to the vitamin D receptor (VDR. Multi-step synthesis of the C/D-ring building block of the tetralone structure was achieved and its enol triflate was coupled with the known A-ring fragments, possessing conjugated enyne moiety, using Sonogashira protocol. The structures of the final products were confirmed by NMR, UV and mass spectroscopy. Their binding affinities for the full-length human VDR were determined and it was established that compound substituted at C-2 with exomethylene group showed significant binding to the receptor. This analog was also able to induce monocytic differentiation of HL-60 cells.

Ring Theory

CERN Document Server

Jara, Pascual; Torrecillas, Blas

1988-01-01

The papers in this proceedings volume are selected research papers in different areas of ring theory, including graded rings, differential operator rings, K-theory of noetherian rings, torsion theory, regular rings, cohomology of algebras, local cohomology of noncommutative rings. The book will be important for mathematicians active in research in ring theory.

Using Tree-Rings and Remote Sensing to Investigate Forest Productivity Response to Landscape Fragmentation in Northeastern Algeria

Science.gov (United States)

Rouini, N.; Lepley, K. S.; Messaoudene, M.

2017-12-01

Remote sensing and dendrochronology are valuable tools in the face of climate change and land use change, yet the connection between these resources remains largely unexploited. Research on forest fragmentation is mainly focused on animal groups, while our work focuses on tree communities. We link tree-rings and remotely-sensed Normalized Difference Vegetation Index (NDVI) using seasonal correlation analysis to investigate forest primary productivity response to fragmentation. Tree core samples from Quercus afares have been taken from two sites within the Guerrouche Forest in northeastern Algeria. The first site is located within a very fragmented area while the second site is intact. Fragmentation is estimated to have occurred with the construction of a road in 1930. We find raw tree-ring width chronologies from each site reveal growth release in the disturbed site after 1930. The means of each chronology for the 1930 to 2016 period are statistically different (p < 0.01). Based on these preliminary results we hypothesize that reconstructed primary productivity (NDVI) will be higher in the fragmented site after fragmentation took place.

Reaction kinetics and oxidation products formation in the degradation of ciprofloxacin and ibuprofen by ferrate(VI).

Science.gov (United States)

Zhou, Zhengwei; Jiang, Jia-Qian

2015-01-01

The treatment of ciprofloxacin (CIP) and ibuprofen (IBU) in test solutions by ferrate(VI) was investigated in this study. A series of jar test was performed in bench-scale at pH 6-9 and ferrate(VI) dose of 1-5 mg L(-1). Results demonstrated that ferrate(VI) removed CIP from test solutions efficiently, with above 70% of reduction under study conditions. In contrary, the removal rates of IBU were very low, less than 25% in all conditions. Raising ferrate(VI) dose improved the treatment performance, while the influence of solution pH was not significant at pH 6-9 compared with that of ferrate(VI) dose. In addition, kinetic studies of ferrate(VI) with both compounds were carried out at pH 8 and pH 9 (20 °C). Ferrate(VI) had a much higher reactivity with CIP than IBU at pH 8 and pH 9, with CIP's apparent second-order rate constants of 113.7±6.3 M(-1) s(-1) and 64.1±1.0 M(-1) s(-1), respectively. The rate constants of ferrate(VI) with IBU were less than 0.2 M(-1) s(-1) at pH 8 and pH 9. Furthermore, seven oxidation products (OPs) were formed during CIP degradation by ferrate(VI). The attack on the piperazinyl ring of the CIP by ferrate(VI) appeared to lead to the cleavage or hydroxylation of the rings, and the attack on the quinolone moiety by ferrate(VI) might lead to the cleavage of the double bond at the six-member heterocyclic ring. No OPs of IBU were detected during ferrate(VI) oxidation due to very small part of IBU was degraded by ferrate(VI). Copyright © 2014 Elsevier Ltd. All rights reserved.

Report of the eRHIC Ring-Ring Working Group

Energy Technology Data Exchange (ETDEWEB)

Aschenauer, E. C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Berg, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Blaskiewicz, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Brennan, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Fedotov, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Fischer, W. [Brookhaven National Lab. (BNL), Upton, NY (United States); Litvinenko, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Montag, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Palmer, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Parker, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Peggs, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ptitsyn, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ranjbar, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Tepikian, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Trbojevic, D. [Brookhaven National Lab. (BNL), Upton, NY (United States); Willeke, F. [Brookhaven National Lab. (BNL), Upton, NY (United States)

2015-10-13

This report evaluates the ring-ring option for eRHIC as a lower risk alternative to the linac-ring option. The reduced risk goes along with a reduced initial luminosity performance. However, a luminosity upgrade path is kept open. This upgrade path consists of two branches, with the ultimate upgrade being either a ring-ring or a linac-ring scheme. The linac-ring upgrade could be almost identical to the proposed linac-ring scheme, which is based on an ERL in the RHIC tunnel. This linac-ring version has been studied in great detail over the past ten years, and its significant risks are known. On the other hand, no detailed work on an ultimate performance ring-ring scenario has been performed yet, other than the development of a consistent parameter set. Pursuing the ring-ring upgrade path introduces high risks and requires significant design work that is beyond the scope of this report.

Perfect state transfer in unitary Cayley graphs over local rings

Directory of Open Access Journals (Sweden)

Yotsanan Meemark

2014-12-01

Full Text Available In this work, using eigenvalues and eigenvectors of unitary Cayley graphs over finite local rings and elementary linear algebra, we characterize which local rings allowing PST occurring in its unitary Cayley graph. Moreover, we have some developments when $R$ is a product of local rings.

Coronavirus 3CLpro proteinase cleavage sites: Possible relevance to SARS virus pathology

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Blom Nikolaj

2004-06-01

Full Text Available Abstract Background Despite the passing of more than a year since the first outbreak of Severe Acute Respiratory Syndrome (SARS, efficient counter-measures are still few and many believe that reappearance of SARS, or a similar disease caused by a coronavirus, is not unlikely. For other virus families like the picornaviruses it is known that pathology is related to proteolytic cleavage of host proteins by viral proteinases. Furthermore, several studies indicate that virus proliferation can be arrested using specific proteinase inhibitors supporting the belief that proteinases are indeed important during infection. Prompted by this, we set out to analyse and predict cleavage by the coronavirus main proteinase using computational methods. Results We retrieved sequence data on seven fully sequenced coronaviruses and identified the main 3CL proteinase cleavage sites in polyproteins using alignments. A neural network was trained to recognise the cleavage sites in the genomes obtaining a sensitivity of 87.0% and a specificity of 99.0%. Several proteins known to be cleaved by other viruses were submitted to prediction as well as proteins suspected relevant in coronavirus pathology. Cleavage sites were predicted in proteins such as the cystic fibrosis transmembrane conductance regulator (CFTR, transcription factors CREB-RP and OCT-1, and components of the ubiquitin pathway. Conclusions Our prediction method NetCorona predicts coronavirus cleavage sites with high specificity and several potential cleavage candidates were identified which might be important to elucidate coronavirus pathology. Furthermore, the method might assist in design of proteinase inhibitors for treatment of SARS and possible future diseases caused by coronaviruses. It is made available for public use at our website: http://www.cbs.dtu.dk/services/NetCorona/.

Tree-ring footprints of drought variability in last ˜300 years over Kumaun Himalaya, India and its relationship with crop productivity

Science.gov (United States)

Yadav, Ram R.; Misra, Krishna G.; Yadava, Akhilesh K.; Kotlia, Bahadur S.; Misra, Sandhya

2015-06-01

We reconstructed Standardized Precipitation Index (SPI), a metric of drought, using tree-ring width chronologies of Himalayan cedar (Cedrus deodara (Roxb.) G. Don) prepared from two ecologically homogeneous settings in the Kumaun Himalaya, India. The reconstruction employing first principal component of the two site chronologies in linear regression model helped in extending 7-month SPI of May (SPI7-May) back to 1720 CE. The calibration model capturing 60% of variance in the observed SPI series (1902-1967) is the strongest so far from the Indian region. On achieving such a robust tree-ring calibration we are of the opinion that SPI should provide a better option to develop long-term drought records for the data scarce Himalayan region. The SPI reconstruction revealed high year-to-year variability with 1816 (SPI -1.92) and 1737 (SPI +2.33) the driest and the wettest years respectively. The five year mean of reconstructed SPI revealed multiyear droughts in 1920-1924, 1782-1786, 1812-1816, 1744-1748, 1964-1968 and pluvial phases in 1911-1915, 1723-1727, 1788-1792, 1758-1762 and 1733-1737. The SPI7-May was found to be significantly correlated with wheat-barley productivity data of Almora in Kumaun, close to our tree ring sites (r = 0.60, two-tailed p cedar trees are in active vegetation phase of seasonal growth in Almora region. We observed strong and significant correlation in SPI7-May and SPI7-April (r = 0.75, two-tailed p = 0.0001) underpinning that the tree-ring derived SPI7-May could also be taken as a proxy of wheat-barley production in Almora region. This observation also stands for the past as we noted that most of the droughts recorded in our reconstruction (SPI tree rings should serve as an important base line data to quantify the impact of droughts on forest as well as rabi crop productivity in hilly terrains of the Kumaun Himalaya in long-term perspective.

Prediction of proteasome cleavage motifs by neural networks

DEFF Research Database (Denmark)

Kesimir, C.; Nussbaum, A.K.; Schild, H.

2002-01-01

physiological conditions. Our algorithm has been trained not only on in vitro data, but also on MHC Class I ligand data, which reflect a combination of immunoproteasome and constitutive proteasome specificity. This feature, together with the use of neural networks, a non-linear classification technique, make...... the prediction of MHC Class I ligand boundaries more accurate: 65% of the cleavage sites and 85% of the non-cleavage sites are correctly determined. Moreover, we show that the neural networks trained on the constitutive proteasome data learns a specificity that differs from that of the networks trained on MHC...

Fused-Ring Formation by an Intramolecular "Cut-and-Sew" Reaction between Cyclobutanones and Alkynes.

Science.gov (United States)

Deng, Lin; Jin, Likun; Dong, Guangbin

2018-03-01

The development of a catalytic intramolecular "cut-and-sew" transformation between cyclobutanones and alkynes to construct cyclohexenone-fused rings is described herein. The challenge arises from the need for selective coupling at the more sterically hindered proximal position, and can be addressed by using an electron-rich, but less bulky, phosphine ligand. The control experiment and 13 C-labelling study suggest that the reaction may start with cleavage of the less hindered distal C-C bond of cyclobutanones, followed by decarbonylation and CO reinsertion to enable Rh insertion at the more hindered proximal position. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Remarkable weakness against cleavage stress for YBCO-coated conductors and its effect on the YBCO coil performance

International Nuclear Information System (INIS)

Yanagisawa, Y.; Nakagome, H.; Takematsu, T.; Takao, T.; Sato, N.; Takahashi, M.; Maeda, H.

2011-01-01

Cleavage strength for YBCO-coated conductor is extremely low, typically 0.5 MPa. The remarkable weakness is due to cracks on the slit edge of the conductor. The cleavage stress appears on YBCO double pancake coils impregnated with epoxy. The cleavage stress should be avoided in the coil winding. Cleavage strength for an YBCO-coated conductor at 77 K was investigated with a model experiment. The nominal cleavage strength for an YBCO-coated conductor is extremely low, typically 0.5 MPa. This low nominal cleavage strength is due to stress concentration on a small part of the YBCO-coated conductor in cleavage fracture. Debonding by the cleavage stress occurs at the interface between the buffer layer and the Hastelloy substrate. The nominal cleavage strength for a slit edge of the conductor is 2.5-times lower than that for the original edge of the conductor; cracks and micro-peel existing over the slit edge reduce the cleavage strength for the slit edge. Cleavage stress and peel stress should be avoided in coil winding, as they easily delaminate the YBCO-coated conductor, resulting in substantial degradation of coil performance. These problems are especially important for epoxy impregnated YBCO-coated conductor coils. It appears that effect of cleavage stress and peel stress are mostly negligible for paraffin impregnated YBCO-coated conductor coils or dry wound YBCO-coated conductor coils.

Non-gaseous radiolysis products of procaine benzylpenicillin and Na salt 3-ortho-chloro-5-methyl-4-isoxasolyl penicillin

International Nuclear Information System (INIS)

Dziegielewski, J.; Jezowska-Trzebiatowska, B.

1974-01-01

Radiolysis products of procaine benzylpenicillin and Na salt 3-ortho-chlorophenyl-5-methyl-4-isoxasolyl penicillin were isolated and spectroscopic studies were made over the NMR, IR, UV and mass spectrometric ranges. On the basis of the results obtained, the bond breakage sites resulting from irradiation were determined and the modes of radiolysis decomposition were suggested. Irradiation of penicillins has been found to result in decomposition of the β-lactam and thiazolidine rings. Besides, decarboxylation of penicillins and bond cleavages within the amide group were observed as well as dehydrogenation and abstraction of simple hydrocarbons. The role of procaine and crystallization water in the radiolysis of penicillins was determined. (author)

Influence of catalytic activity and reaction conditions on the product distribution in coal liquefaction; Sekitan ekikayu no seiseibutsu bunpu ni taisuru shokubai kassei oyobi hanno joken no eikyo

Energy Technology Data Exchange (ETDEWEB)

Hasuo, H.; Sakanishi, K.; Mochida, I. [Kyushu University, Fukuoka (Japan). Institute of Advanced Material Study

1996-10-28

The NiMo sulfide supported on Ketjen Black (KB) was more effective and yielded lighter oil products containing light fractions with their boiling point below 300{degree}C during the two stage liquefaction combining low temperature and high temperature hydrogenation the conventional NiMo/alumina catalyst and FeS2 catalyst. Although the NiMo/alumina yielded increased oil products during the two stage liquefaction, the lighter oil fractions did not increase and the heavier fractions increased mainly. This suggests that the hydrogenation of aromatic rings and successive cleavage of the rings are necessary for producing the light oil, which is derived from the sufficient hydrogenation of aromatic rings using catalysts. For the two stage reaction with NiMo/KB catalyst, it was considered that sufficient hydrogen was directly transferred to coal molecules at the first stage of the low temperature reaction, which promoted the solubilization of coal and the successive hydrogenation at the high temperature reaction. Thus, high activity of the catalyst must be obtained. It is expected that further high quality distillates can be produced through the optimization of catalysts and solvents at the two stage reaction. 1 ref., 4 figs., 1 tab.

Flanking signal and mature peptide residues influence signal peptide cleavage

Directory of Open Access Journals (Sweden)

Ranganathan Shoba

2008-12-01

Full Text Available Abstract Background Signal peptides (SPs mediate the targeting of secretory precursor proteins to the correct subcellular compartments in prokaryotes and eukaryotes. Identifying these transient peptides is crucial to the medical, food and beverage and biotechnology industries yet our understanding of these peptides remains limited. This paper examines the most common type of signal peptides cleavable by the endoprotease signal peptidase I (SPase I, and the residues flanking the cleavage sites of three groups of signal peptide sequences, namely (i eukaryotes (Euk (ii Gram-positive (Gram+ bacteria, and (iii Gram-negative (Gram- bacteria. Results In this study, 2352 secretory peptide sequences from a variety of organisms with amino-terminal SPs are extracted from the manually curated SPdb database for analysis based on physicochemical properties such as pI, aliphatic index, GRAVY score, hydrophobicity, net charge and position-specific residue preferences. Our findings show that the three groups share several similarities in general, but they display distinctive features upon examination in terms of their amino acid compositions and frequencies, and various physico-chemical properties. Thus, analysis or prediction of their sequences should be separated and treated as distinct groups. Conclusion We conclude that the peptide segment recognized by SPase I extends to the start of the mature protein to a limited extent, upon our survey of the amino acid residues surrounding the cleavage processing site. These flanking residues possibly influence the cleavage processing and contribute to non-canonical cleavage sites. Our findings are applicable in defining more accurate prediction tools for recognition and identification of cleavage site of SPs.

Staggering in the cleavage pattern of E. coli ABC-excinuclease

International Nuclear Information System (INIS)

Myles, G.M.; Van Houten, B.; Sancar, A.

1986-01-01

E. coli ABC excinuclease is a complex of three proteins encoded by the uvrA, uvrB, and uvrC genes. The enzyme repairs DNA mono and diadducts by the single strand cleavage of DNA eight phosphodiester bond 5' and four or five phosphodiester bonds 3' to a DNA lesion and facilitates the removal of the resulting twelve or thirteen nucleotide fragment. In this study, the authors have investigated the excision pattern for ultraviolet (UV) induced diadducts, i.e. cyclobutane pyrimidine dimers and pyrimidine-pyrimidone (6-4) photoproducts. Terminally (5' or 3') labeled DNA was irradiated with 254nm UV and treated with ABC excinuclease before and after photoreactivation of cyclobutane dimers by E. coli DNA photolyase. In this way, the authors were able to differentiate between the cleavage pattern of pyrimidine dimers and of (6-4) photoproducts. Their results show that certain TT cyclobutane dimers and rare TT (6-4) photoproducts are excised by cleavage seven and, less frequently, six phosphodiester bonds to the 5' side of the DNA lesion in addition to the primary cutting site at the eight 5' phosphodiester bond. The 3' cleavage sites are maintained at the fourth and fifth phosphodiester bonds for the these UV induced lesions. These data indicate that the cleavage pattern of the ABC excinuclease may be dependent upon both the type of DNA lesion as well as it surrounding nucleotide sequence. In addition, the authors analysis shows that (6-4) photoproducts are much better substrates for ABC excinuclease than are pyrimidine dimers

Downstream element determines RNase Y cleavage of the saePQRS operon in Staphylococcus aureus.

Science.gov (United States)

Marincola, Gabriella; Wolz, Christiane

2017-06-02

In gram-positive bacteria, RNase J1, RNase J2 and RNase Y are thought to be major contributors to mRNA degradation and maturation. In Staphylococcus aureus, RNase Y activity is restricted to regulating the mRNA decay of only certain transcripts. Here the saePQRS operon was used as a model to analyze RNase Y specificity in living cells. A RNase Y cleavage site is located in an intergenic region between saeP and saeQ. This cleavage resulted in rapid degradation of the upstream fragment and stabilization of the downstream fragment. Thereby, the expression ratio of the different components of the operon was shifted towards saeRS, emphasizing the regulatory role of RNase Y activity. To assess cleavage specificity different regions surrounding the sae CS were cloned upstream of truncated gfp, and processing was analyzed in vivo using probes up- and downstream of CS. RNase Y cleavage was not determined by the cleavage site sequence. Instead a 24-bp double-stranded recognition structure was identified that was required to initiate cleavage 6 nt upstream. The results indicate that RNase Y activity is determined by secondary structure recognition determinants, which guide cleavage from a distance. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Protein cleavage strategies for an improved analysis of the membrane proteome

Directory of Open Access Journals (Sweden)

Poetsch Ansgar

2006-03-01

Full Text Available Abstract Background Membrane proteins still remain elusive in proteomic studies. This is in part due to the distribution of the amino acids lysine and arginine, which are less frequent in integral membrane proteins and almost absent in transmembrane helices. As these amino acids are cleavage targets for the commonly used protease trypsin, alternative cleavage conditions, which should improve membrane protein analysis, were tested by in silico digestion for the three organisms Saccharomyces cerevisiae, Halobacterium sp. NRC-1, and Corynebacterium glutamicum as hallmarks for eukaryotes, archea and eubacteria. Results For the membrane proteomes from all three analyzed organisms, we identified cleavage conditions that achieve better sequence and proteome coverage than trypsin. Greater improvement was obtained for bacteria than for yeast, which was attributed to differences in protein size and GRAVY. It was demonstrated for bacteriorhodopsin that the in silico predictions agree well with the experimental observations. Conclusion For all three examined organisms, it was found that a combination of chymotrypsin and staphylococcal peptidase I gave significantly better results than trypsin. As some of the improved cleavage conditions are not more elaborate than trypsin digestion and have been proven useful in practice, we suppose that the cleavage at both hydrophilic and hydrophobic amino acids should facilitate in general the analysis of membrane proteins for all organisms.

Cleavage and Cell Adhesion Properties of Human Epithelial Cell Adhesion Molecule (HEPCAM)*

Science.gov (United States)

Tsaktanis, Thanos; Kremling, Heidi; Pavšič, Miha; von Stackelberg, Ricarda; Mack, Brigitte; Fukumori, Akio; Steiner, Harald; Vielmuth, Franziska; Spindler, Volker; Huang, Zhe; Jakubowski, Jasmine; Stoecklein, Nikolas H.; Luxenburger, Elke; Lauber, Kirsten; Lenarčič, Brigita; Gires, Olivier

2015-01-01

Human epithelial cell adhesion molecule (HEPCAM) is a tumor-associated antigen frequently expressed in carcinomas, which promotes proliferation after regulated intramembrane proteolysis. Here, we describe extracellular shedding of HEPCAM at two α-sites through a disintegrin and metalloprotease (ADAM) and at one β-site through BACE1. Transmembrane cleavage by γ-secretase occurs at three γ-sites to generate extracellular Aβ-like fragments and at two ϵ-sites to release human EPCAM intracellular domain HEPICD, which is efficiently degraded by the proteasome. Mapping of cleavage sites onto three-dimensional structures of HEPEX cis-dimer predicted conditional availability of α- and β-sites. Endocytosis of HEPCAM warrants acidification in cytoplasmic vesicles to dissociate protein cis-dimers required for cleavage by BACE1 at low pH values. Intramembrane cleavage sites are accessible and not part of the structurally important transmembrane helix dimer crossing region. Surprisingly, neither chemical inhibition of cleavage nor cellular knock-out of HEPCAM using CRISPR-Cas9 technology impacted the adhesion of carcinoma cell lines. Hence, a direct function of HEPCAM as an adhesion molecule in carcinoma cells is not supported and appears to be questionable. PMID:26292218

Characterization of a Non-Canonical Signal Peptidase Cleavage Site in a Replication Protein from Tomato Ringspot Virus.

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Ting Wei

Full Text Available The NTB-VPg polyprotein from tomato ringspot virus is an integral membrane replication protein associated with endoplasmic reticulum membranes. A signal peptidase (SPase cleavage was previously detected in the C-terminal region of NTB-VPg downstream of a 14 amino acid (aa-long hydrophobic region (termed TM2. However, the exact location of the cleavage site was not determined. Using in vitro translation assays, we show that the SPase cleavage site is conserved in the NTB-VPg protein from various ToRSV isolates, although the rate of cleavage varies from one isolate to another. Systematic site-directed mutagenesis of the NTB-VPg SPase cleavage sites of two ToRSV isolates allowed the identification of sequences that affect cleavage efficiency. We also present evidence that SPase cleavage in the ToRSV-Rasp2 isolate occurs within a GAAGG sequence likely after the AAG (GAAG/G. Mutation of a downstream MAAV sequence to AAAV resulted in SPase cleavage at both the natural GAAG/G and the mutated AAA/V sequences. Given that there is a distance of seven aa between the two cleavage sites, this indicates that there is flexibility in the positioning of the cleavage sites relative to the inner surface of the membrane and the SPase active site. SPase cleavage sites are typically located 3-7 aa downstream of the hydrophobic region. However, the NTB-VPg GAAG/G cleavage site is located 17 aa downstream of the TM2 hydrophobic region, highlighting unusual features of the NTB-VPg SPase cleavage site. A putative 11 aa-long amphipathic helix was identified immediately downstream of the TM2 region and five aa upstream of the GAAG/G cleavage site. Based on these results, we present an updated topology model in which the hydrophobic and amphipathic domains form a long tilted helix or a bent helix in the membrane lipid bilayer, with the downstream cleavage site(s oriented parallel to the membrane inner surface.

Influence of feed rate on damage development in hot ring rolling

NARCIS (Netherlands)

Wang, Chao; van den Boogaard, Antonius H.; Omerspahic, E.; Recina, V.; Geijselaers, Hubertus J.M.; Ishikawa, T.; Mori, K.-I.

2014-01-01

As an incremental forming process of bulk metal, ring rolling provides a cost effective process route to manufacture seamless rings. Applications of ring rolling cover a wide range of products in aerospace, automotive and civil engineering industries. Under some process conditions, defects such as

Efficient Low Rank Tensor Ring Completion

OpenAIRE

Wang, Wenqi; Aggarwal, Vaneet; Aeron, Shuchin

2017-01-01

Using the matrix product state (MPS) representation of the recently proposed tensor ring decompositions, in this paper we propose a tensor completion algorithm, which is an alternating minimization algorithm that alternates over the factors in the MPS representation. This development is motivated in part by the success of matrix completion algorithms that alternate over the (low-rank) factors. In this paper, we propose a spectral initialization for the tensor ring completion algorithm and ana...

ASSOCIATIVE RINGS SOLVED AS LIE RINGS

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M. B. Smirnov

2011-01-01

Full Text Available The paper has proved that an associative ring which is solvable of a n- class as a Lie ring has a nilpotent ideal of the nilpotent class not more than 3×10n–2  and a corresponding quotient ring satisfies an identity [[x1, x2, [x3, x4

Quantum correlation properties in Matrix Product States of finite-number spin rings

Science.gov (United States)

Zhu, Jing-Min; He, Qi-Kai

2018-02-01

The organization and structure of quantum correlation (QC) of quantum spin-chains are very rich and complex. Hence the depiction and measures about the QC of finite-number spin rings deserved to be investigated intensively by using Matrix Product States(MPSs) in addition to the case with infinite-number. Here the dependencies of the geometric quantum discord(GQD) of two spin blocks on the total spin number, the spacing spin number and the environment parameter are presented in detail. We also compare the GQD with the total correlation(TC) and the classical correlation(CC) and illustrate its characteristics. Predictably, our findings may provide the potential of designing the optimal QC experimental detection proposals and pave the way for the designation of optimal quantum information processing schemes.

Estudo das condições reacionais da reação de clivagem oxidativa de β-hidróxi éteres bicíclicos promovida por tetróxido de rutênio Study of the conditions of the ruthenium tetraoxide-promoted oxidative cleavage reaction of bicyclic β-hydroxy ethers

Directory of Open Access Journals (Sweden)

Helena M. C. Ferraz

2010-01-01

Full Text Available A systematic study of the reaction of β-hydroxy ethers with ruthenium tetraoxide (RuO4, generated in situ from ruthenium trichloride and sodium periodate, is presented, leading to nine-membered ring keto-lactones in moderate yields. Three different solvent systems - AcOEt/MeCN/H2O, MeCN/H2O and DMC/H2O - were studied leading to the desired products in lower yields than those obtained with the classical mixture of CCl4/MeCN/H2O, commonly used in reactions promoted by this oxidant. However, it is noteworthy that these new solvent systems represent greener alternatives to the chlorinated solvents used in the oxidative cleavage of β-hydroxy ethers by RuO4.

Molecular structure, vibrational spectra and photochemistry of 5-mercapto-1-methyltetrazole

Science.gov (United States)

Gómez-Zavaglia, A.; Reva, I. D.; Frija, L.; Cristiano, M. L.; Fausto, R.

2006-04-01

In this work, 5-mercapto-1-methyltetrazole was studied by low temperature matrix-isolation and solid-state infrared spectroscopy, DFT(B3LYP)/6-311++G(d,p) calculations and photochemical methods. In the low temperature neat solid phase and isolated in an argon matrix, the compound was found to exist in the 1-methyl-1,4-dihydro-5 H-tetrazole-5-thione tautomeric form. The infrared spectra of the compound were fully assigned and correlated with structural properties. In situ UV-irradiation ( λ>235 nm) of the matrix-isolated monomer is shown to induce different photochemical processes, all of them involving cleavage of the tetrazole ring: e.g. (1) molecular nitrogen expulsion, with production of 1-methyl-1 H-diazirene-3-thiol, which is produced in two different conformers; (2) ring cleavage leading to production of methyl isothiocyanate and azide; (3) simultaneous elimination of nitrogen and sulphur with production of N-methylcarbodiimide. Following these photoprocesses, subsequent reactions occur, leading to production of methyl diazene, carbon monosulphide and nitrogen hydride. Spectroscopic evidence of the production of the above-mentioned chemical species is provided.

Specific in vitro cleavage of Mason-Pfizer monkey virus capsid protein: evidence for a potential role of retroviral protease in early stages of infection

International Nuclear Information System (INIS)

Rumlova, Michaela; Ruml, Tomas; Pohl, Jan; Pichova, Iva

2003-01-01

Processing of Gag polyproteins by viral protease (PR) leads to reorganization of immature retroviral particles and formation of a ribonucleoprotein core. In some retroviruses, such as HIV and RSV, cleavage of a spacer peptide separating capsid and nucleocapsid proteins is essential for the core formation. We show here that no similar spacer peptide is present in the capsid-nucleocapsid (CA-NC) region of Mason-Pfizer monkey virus (M-PMV) and that the CA protein is cleaved in vitro by the PR within the major homology region (MHR) and the NC protein in several sites at the N-terminus. The CA cleavage product was also identified shortly after penetration of M-PMV into COS cells, suggesting that the protease-catalyzed cleavage is involved in core disintegration

Beam dynamics in Compton ring gamma sources

Directory of Open Access Journals (Sweden)

Eugene Bulyak

2006-09-01

Full Text Available Electron storage rings of GeV energy with laser pulse stacking cavities are promising intense sources of polarized hard photons which, via pair production, can be used to generate polarized positron beams. In this paper, the dynamics of electron bunches circulating in a storage ring and interacting with high-power laser pulses is studied both analytically and by simulation. Both the common features and the differences in the behavior of bunches interacting with an extremely high power laser pulse and with a moderate pulse are discussed. Also considerations on particular lattice designs for Compton gamma rings are presented.

Optimization and Simulation of Machining Parameters in Radial-axial Ring Rolling Process

Directory of Open Access Journals (Sweden)

Shuiyuan Tang

2011-05-01

Full Text Available Ring rolling is a complicated process, in which rolling parameters influence directly the quality of ring. It is a process method with high productivity and few waste of material, widely used in transportation industry including automotive, shipbuilding, aerospace etc. During the rolling process of large-sized parts, crinkle and hollows often appear on surface, due to inconsistence of rolling motions with the deformation of ring part. Based on radial-axial ring rolling system configuration, motions and forces in rolling process are analyzed, and a dynamic model is formulated. Error of ring's end flatness and roundness are defined as the characteristic parameters of ring quality. The relationship between core roller feed speed, drive roller speed, the upper taper roller feed speed, and quality of ring part are analyzed. The stress and strain of the part are simulated in the Finite Element Method by DEFORM software. The simulation results provide a reference for the definition of ring rolling process parameters. It is able to make the deformation of the part be consistent with the process parameters, and improve product quality considerably.

Ring rolling process simulation for geometry optimization

Science.gov (United States)

Franchi, Rodolfo; Del Prete, Antonio; Donatiello, Iolanda; Calabrese, Maurizio

2017-10-01

Ring Rolling is a complex hot forming process where different rolls are involved in the production of seamless rings. Since each roll must be independently controlled, different speed laws must be set; usually, in the industrial environment, a milling curve is introduced to monitor the shape of the workpiece during the deformation in order to ensure the correct ring production. In the present paper a ring rolling process has been studied and optimized in order to obtain anular components to be used in aerospace applications. In particular, the influence of process input parameters (feed rate of the mandrel and angular speed of main roll) on geometrical features of the final ring has been evaluated. For this purpose, a three-dimensional finite element model for HRR (Hot Ring Rolling) has been implemented in SFTC DEFORM V11. The FEM model has been used to formulate a proper optimization problem. The optimization procedure has been implemented in the commercial software DS ISight in order to find the combination of process parameters which allows to minimize the percentage error of each obtained dimension with respect to its nominal value. The software allows to find the relationship between input and output parameters applying Response Surface Methodology (RSM), by using the exact values of output parameters in the control points of the design space explored through FEM simulation. Once this relationship is known, the values of the output parameters can be calculated for each combination of the input parameters. After the calculation of the response surfaces for the selected output parameters, an optimization procedure based on Genetic Algorithms has been applied. At the end, the error between each obtained dimension and its nominal value has been minimized. The constraints imposed were the maximum values of standard deviations of the dimensions obtained for the final ring.

Effect of Presenilin Mutations on APP Cleavage; Insights into the Pathogenesis of FAD

OpenAIRE

Li, Nuomin; Liu, Kefu; Qiu, Yunjie; Ren, Zehui; Dai, Rongji; Deng, Yulin; Qing, Hong

2016-01-01

Alzheimer disease (AD) is characterized by progressive memory loss, reduction in cognitive functions, and damage to the brain. The β-amyloid precursor protein can be sequentially cleaved by β- secretase and γ-secretase. Mutations in the presenilin1(PS1) are the most common cause of Familial Alzheimer’s disease (FAD). PS1 mutations can alter the activity of γ-secretase on the cleavage of the β-amyloid precursor protein, causing increased Aβ production. Previous studies show that the βAPP-C-ter...

Fluorescence-based high-throughput screening of dicer cleavage activity.

Science.gov (United States)

Podolska, Katerina; Sedlak, David; Bartunek, Petr; Svoboda, Petr

2014-03-01

Production of small RNAs by ribonuclease III Dicer is a key step in microRNA and RNA interference pathways, which employ Dicer-produced small RNAs as sequence-specific silencing guides. Further studies and manipulations of microRNA and RNA interference pathways would benefit from identification of small-molecule modulators. Here, we report a study of a fluorescence-based in vitro Dicer cleavage assay, which was adapted for high-throughput screening. The kinetic assay can be performed under single-turnover conditions (35 nM substrate and 70 nM Dicer) in a small volume (5 µL), which makes it suitable for high-throughput screening in a 1536-well format. As a proof of principle, a small library of bioactive compounds was analyzed, demonstrating potential of the assay.

[Recent knowledge about intestinal absorption and cleavage of carotenoids].

Science.gov (United States)

Borel, P; Drai, J; Faure, H; Fayol, V; Galabert, C; Laromiguière, M; Le Moël, G

2005-01-01

Our knowledge about intestinal absorption and cleavage of carotenoids has rapidly grown during the last years. New facts about carotenoid absorption have emerged while some controversies about cleavage are close to end. The knowledge of the absorption and conversion processes is indispensable to understand and interpret the perturbations that can occur in the metabolism of carotenoids and vitamin A. Recently, it has been shown that the absorption of certain carotenoids is not passive - as believed for a long time - but is a facilitated process that requires, at least for lutein, the class B-type 1 scavenger receptor (SR-B1). Various epidemiological and clinical studies have shown wide variations in carotenoid absorption from one subject to another, such differences are now explained by the structure of the concerned carotenoid, by the nature of the food that is absorbed with the carotenoid, by diverse exogenous factors like the intake of medicines or interfering components, by diet factors, by genetic factors, and by the nutritional status of the subject. Recently, the precise mechanism of beta-carotene cleavage by betabeta-carotene 15,15' monooxygenase (EC 1.14.99.36) - formerly called beta-carotene 15,15' dioxygenase (ex EC 1.13.11.21) - has been discovered, and a second enzyme which cleaves asymmetrically the beta-carotene molecule has been found. beta-carotene 15,15' monooxygenase only acts on the 15,15' bond, thus forming two molecules of retinal from one molecule of beta-carotene by central cleavage. Even though the betabeta-carotene 15,15' monooxygenase is much more active on the beta-carotene molecule, a study has shown that it can act on all carotenoids. Searchers now agree that other enzymes that can catalyse an eccentric cleavage of carotenoids probably exist, but under physiological conditions the betabeta-carotene 15,15' monooxygenase is by far the most active, and it is mainly effective in the small bowel mucosa and in the liver. However the

Endocytic down-regulation of ErbB2 is stimulated by cleavage of its C-terminus

DEFF Research Database (Denmark)

Lerdrup, Mads; Bruun, Silas; Grandal, Michael Vibo

2007-01-01

inhibition of HSP90 with geldanamycin this cleavage is accompanied by proteasome-dependent endocytosis of ErbB2. However, it is unknown whether C-terminal cleavage is linked to endocytosis. To study ErbB2 cleavage and endocytic trafficking, we fused yellow fluorescent protein (YFP) and cyan fluorescent...

Effects of Cysteamine on Sheep Embryo Cleavage Rates

Directory of Open Access Journals (Sweden)

Sinem Ö. ENGİNLER

2015-01-01

Full Text Available Oxidative stress during in vitro culture leads to defects in development of gametes and embryos. Several antioxidants such as cysteamine, L-ascorbic acid, beta mercaptoethanol, cysteine, glutathione, proteins, vitamins have been used to supplement culture media to counter the oxidative stress. This study was conducted to detect the effect of adding cysteamine to the maturation medium to subsequent cleavage rates of sheep embryos. Totally 604 ovaries were obtained by ten replica and 2060 oocytes were collected. The cumulus oocyte complexes were recovered by the slicing method. A total of 1818 selected oocytes were divided into two groups and used for maturation (88.25%. The first group was created as supplemented with cysteamine (Group A and second group (Group B, control without cysteamine in TCM-199. The two groups were incubated for 24 h at 38.8 °C in an atmosphere of 5% CO2 in humidified air for in vitro maturation (IVM. After IVM, oocytes were fertilized with 50 x 107 / mL fresh ram semen in BSOF medium for 18 h. After fertilization, maturation groups were divided into two subgroups with different culture media: Group AI-SOF (Synthetic Oviduct Fluid medium, Group AII-CR1aa (Charles Rosencrans medium, Group BI-SOF and Group BII-CR1aa were achieved. Cleavage rates were evaluated at day 2. post insemination. The rates of cleavage were detected as 59.54% (184/309, 55.44% (173/312, 65.34% (215/329, 59.34% (200/337 respectively, with showing no statistically significant difference between the groups at the level of P>0.05. In conclusion, supplementing cysteamine to maturation media in TCM-199 did not affect the cleavage rates of sheep embryos in SOF and CR1aa culture media.

Reversible Heterolytic Cleavage of the H-H Bond by Molybdenum Complexes: Controlling the Dynamics of Exchange Between Proton and Hydride

Energy Technology Data Exchange (ETDEWEB)

Zhang, Shaoguang; Appel, Aaron M.; Bullock, R. Morris

2017-05-18

Controlling the heterolytic cleavage of the H-H bond of dihydrogen is critically important in catalytic hydrogenations and in the catalytic oxidation of H2. We show how the rate of reversible heterolytic cleavage of H2 can be controlled over nearly four orders of magnitude at 25 °C, from 2.1 × 103 s-1 to ≥107 s-1. Bifunctional Mo complexes, [CpMo(CO)(κ3-P2N2)]+ (P2N2 = 1,5-diaza-3,7-diphosphacyclooctane with alkyl/aryl groups on N and P), have been developed for heterolytic cleavage of H2 into a proton and a hydride, akin to Frustrated Lewis Pairs. The H-H bond cleavage is enabled by the basic amine in the second coordination sphere. The products of heterolytic cleavage of H2, Mo hydride complexes bearing protonated amines, [CpMo(H)(CO)(P2N2H)]+, were characterized by spectroscopic studies and by X-ray crystallography. Variable temperature 1H, 15N and 2-D 1H-1H ROESY NMR spectra indicated rapid exchange of the proton and hydride. The exchange rates are in the order [CpMo(H)(CO)(PPh2NPh2H)]+ > [CpMo(H)(CO)(PtBu2NPh2H)]+ > [CpMo(H)(CO)(PPh2NBn2H)]+ > [CpMo(H)(CO)(PtBu2NBn2H)]+ > [CpMo(H)(CO)(PtBu2NtBu2H)]+. The pKa values determined in acetonitrile range from 9.3 to 17.7, and show a linear correlation with the logarithm of the exchange rates. Thus the exchange dynamics are controlled through the relative acidity of the [CpMo(H)(CO)(P2N2H)]+ and [CpMo(H2)(CO)(P2N2)]+ isomers, providing a design principle for controlling heterolytic cleavage of H2.

Interactions of tetracationic porphyrins with DNA and their effects on DNA cleavage

Science.gov (United States)

Lebedeva, Natalya Sh.; Yurina, Elena S.; Gubarev, Yury A.; Syrbu, Sergey A.

2018-06-01

The interaction of tetracationic porphyrins with DNA was studied using UV-Vis absorption, fluorescence spectroscopy and viscometry, and the particle sizes were determined. Аs cationic porphyrins, two isomer porphyrins, 3,3‧,3″,3‴-(5,10,15,20-Porphyrintetrayl)tetrakis(1-methylpyridinium) (TMPyP3) and 4,4‧,4″,4‴-(5,10,15,20-Porphyrintetrayl)tetrakis(1-methylpyridinium) (TMPyP4), were studied. They differ in the position of NCH3+ group in phenyl ring of the porphyrins and hence, in degree of freedom of rotation of the phenyl rings about the central macrocycle. It was found that intercalated complexes are formed at DNA/porphyrin molar ratios (R) of 2.2 and 3.9 for TMPyP3 и TMPyP4, respectively. Decreasing R up to 0.4 and 0.8 for TMPyP3 и TMPyP4, respectively, leads mainly to formation of outside complexes due to π-π stacking between the porphyrin chromophores interacting electrostatically with phosphate framework of DNA. Each type of the obtained complexes was characterized using Scatchard approach. It was ascertained that the affinity of TMPyP4 to DNA is stronger than TMPyP3, meanwhile the wedge effect of the latter is higher. The differences between the porphyrin isomers become more evident at irradiation of their complexes with DNA. It was established that irradiation of the intercalated complexes results in DNA fragmentation. In the case of TMPyP4, DNA fragments of different size are formed. The irradiation of the outside DNA/porphyrin complexes leads to cleavage of DNA (TMPyP3 and TMPyP4) and partial destruction of the complex due to photolysis of the porphyrin (TMPyP3).

Mapping Ring Particle Cooling across Saturn's Rings with Cassini CIRS

Science.gov (United States)

Brooks, Shawn M.; Spilker, L. J.; Edgington, S. G.; Pilorz, S. H.; Deau, E.

2010-10-01

Previous studies have shown that the rings' thermal inertia, a measure of their response to changes in the thermal environment, varies from ring to ring. Thermal inertia can provide insight into the physical structure of Saturn's ring particles and their regoliths. Low thermal inertia and quick temperature responses are suggestive of ring particles that have more porous or fluffy regoliths or that are riddled with cracks. Solid, coherent particles can be expected to have higher thermal inertias (Ferrari et al. 2005). Cassini's Composite Infrared Spectrometer has recorded millions of spectra of Saturn's rings since its arrival at Saturn in 2004 (personal communication, M. Segura). CIRS records far infrared radiation between 10 and 600 cm-1 (16.7 and 1000 µm) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermal emission from Saturn's rings peaks in this wavelength range. FP1 spectra can be used to infer ring temperatures. By tracking how ring temperatures vary, we can determine the thermal inertia of the rings. In this work we focus on CIRS observations of the shadowed portion of Saturn's rings. The thermal budget of the rings is dominated by the solar radiation absorbed by its constituent particles. When ring particles enter Saturn's shadow this source of energy is abruptly cut off. As a result, ring particles cool as they traverse Saturn's shadow. From these shadow observations we can create cooling curves at specific locations across the rings. We will show that the rings' cooling curves and thus their thermal inertia vary not only from ring to ring, but by location within the individual rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

SXLS storage ring design

International Nuclear Information System (INIS)

Anon.

1991-01-01

X-ray lithography has emerged as a strong candidate to meet the demands of ever finer linewidths on integrated circuits, particularly for linewidths less than .25 microns. Proximity printing X-ray lithography makes use of soft X-rays to shadow print an image of a mask onto a semiconductor wafer to produce integrated circuits. To generate the required X-rays in sufficient quantities to make commercial production viable, electron storage rings have been proposed as the soft X-ray sources. Existing storage rings have been used to do the initial development work and the success of these efforts has led the lithographers to request that new rings be constructed that are dedicated to X-ray lithography. As a result of a series of workshops held at BNL [10.3] which were attended by both semiconductor and accelerator scientists, the following set of zeroth order specifications' on the light and electron beam of a storage ring for X-ray lithography were developed: critical wavelength of light: λ c = 6 to 10 angstroms, white light power: P = 0.25 to 2.5 watts/mrad, horizontal collection angle per port: θ = 10 to 50 mrad, electron beam sizes: σ x ∼ σ y y ' < 1 mrad

Biomarkers and biometric measures of adherence to use of ARV-based vaginal rings.

Science.gov (United States)

Stalter, Randy M; Moench, Thomas R; MacQueen, Kathleen M; Tolley, Elizabeth E; Owen, Derek H

2016-01-01

Poor adherence to product use has been observed in recent trials of antiretroviral (ARV)-based oral and vaginal gel HIV prevention products, resulting in an inability to determine product efficacy. The delivery of microbicides through vaginal rings is widely perceived as a way to achieve better adherence but vaginal rings do not eliminate the adherence challenges exhibited in clinical trials. Improved objective measures of adherence are needed as new ARV-based vaginal ring products enter the clinical trial stage. To identify technologies that have potential future application for vaginal ring adherence measurement, a comprehensive literature search was conducted that covered a number of biomedical and public health databases, including PubMed, Embase, POPLINE and the Web of Science. Published patents and patent applications were also searched. Technical experts were also consulted to gather more information and help evaluate identified technologies. Approaches were evaluated as to feasibility of development and clinical trial implementation, cost and technical strength. Numerous approaches were identified through our landscape analysis and classified as either point measures or cumulative measures of vaginal ring adherence. Point measurements are those that give a measure of adherence at a particular point in time. Cumulative measures attempt to measure ring adherence over a period of time. Approaches that require modifications to an existing ring product are at a significant disadvantage, as this will likely introduce additional regulatory barriers to the development process and increase manufacturing costs. From the point of view of clinical trial implementation, desirable attributes would be high acceptance by trial participants, and little or no additional time or training requirements on the part of participants or clinic staff. We have identified four promising approaches as being high priority for further development based on the following measurements

Variable context Markov chains for HIV protease cleavage site prediction.

Science.gov (United States)

Oğul, Hasan

2009-06-01

Deciphering the knowledge of HIV protease specificity and developing computational tools for detecting its cleavage sites in protein polypeptide chain are very desirable for designing efficient and specific chemical inhibitors to prevent acquired immunodeficiency syndrome. In this study, we developed a generative model based on a generalization of variable order Markov chains (VOMC) for peptide sequences and adapted the model for prediction of their cleavability by certain proteases. The new method, called variable context Markov chains (VCMC), attempts to identify the context equivalence based on the evolutionary similarities between individual amino acids. It was applied for HIV-1 protease cleavage site prediction problem and shown to outperform existing methods in terms of prediction accuracy on a common dataset. In general, the method is a promising tool for prediction of cleavage sites of all proteases and encouraged to be used for any kind of peptide classification problem as well.

Electric fields, electron production, and electron motion at the stripper foil in the Los Alamos Proton Storage Ring

International Nuclear Information System (INIS)

Plum, M.

1995-01-01

The beam instability at the Los Alamos Proton Storage Ring (PSR) most likely involves coupled oscillations between electrons and protons. For this instability to occur, there must be a strong source of electrons. Investigation of the various sources of electrons in the PSR had begun. Copious electron production is expected in the injection section because this section contains the stripper foil. This foil is mounted near the center of the beam pipe, and both circulating and injected protons pass through it, thus allowing ample opportunity for electron production. This paper discusses various mechanisms for electron production, beam-induced electric fields, and electron motion in the vicinity of the foil

Alanine substitutions in the GXXXG motif alter C99 cleavage by γ-secretase but not its dimerization.

Science.gov (United States)

Higashide, Hidekazu; Ishihara, Seiko; Nobuhara, Mika; Ihara, Yasuo; Funamoto, Satoru

2017-03-01

The amyloid β (Aβ) protein is a major component of senile plaques, one of the neuropathological hallmarks of Alzheimer's disease. Amyloidogenic processing of amyloid precursor protein (APP) by β- and γ-secretases leads to production of Aβ. APP contains tandem triple repeats of the GXXXG motif in its extracellular juxtamembrane and transmembrane regions. It is reported that the GXXXG motif is related to protein-protein interactions, but it remains controversial whether the GXXXG motif in APP is involved in substrate dimerization and whether dimerization affects γ-secretase-dependent cleavage. Therefore, the relationship between the GXXXG motifs, substrate dimerization, and γ-secretase-dependent cleavage sites remains unclear. Here, we applied blue native poly acrylamide gel electrophoresis to examine the effect of alanine substitutions within the GXXXG motifs of APP carboxyl terminal fragment (C99) on its dimerization and Aβ production. Surprisingly, alanine substitutions in the motif failed to alter C99 dimerization in detergent soluble state. Cell-based and solubilized γ-secretase assays demonstrated that increasing alanine substitutions in the motif tended to decrease long Aβ species such as Aβ42 and Aβ43 and to increase in short Aβ species concomitantly. Our data suggest that the GXXXG motif is crucial for Aβ production, but not for C99 dimerization. © 2016 International Society for Neurochemistry.

Prediction of cleavage crack propagation and arrest in a nuclear pressure vessel steel (16MND5) under thermal shock

International Nuclear Information System (INIS)

Yang, Xiaoyu

2015-01-01

The purpose of this PhD study is to predict the propagation and arrest of cleavage cracks in a French PWR vessel steel (16MND5). This is accomplished through use of a local criterion based on the critical stress calculated ahead of crack tip. Previous work has shown that fracture mechanism was cleavage associated with the ductile shear zone between the different planes of cracking. Thus, the critical stress at crack tip depends on stain rate. This thesis consists of numerical optimization, identification and validation of a local criterion based on experiments which have complex thermomechanical loads. The criterion accounts for various crack paths, deepening the knowledge about micro mechanisms during crack propagation in order to justify the established criterion. Criterion identification was carried out by using numerical simulations of tension tests performed on CT (Compact Tension) specimens at four different temperatures (-150 C, -125 C, -100 C and -75 C). The eXtended Finite Element Method (X-FEM) was used in CAST3M FE software to model dynamic crack propagation and arrest. The analysis results in 2D and 3D showed that the critical stress at crack tip increased with the inelastic strain rate. Therefore, a criterion based on the critical stress was established. An analytical model was developed to justify the identified criterion. The critical stress given by the local criterion was considered as the sum of the critical cleavage stress and the stress generated by the deformation of ligaments behind the crack tip. In order to quantify this phenomenon, measurements of ligaments' characteristics have been performed on fracture surfaces and on cross-sections of the specimens. The stress profile of the crack lips generated by ligaments was calculated by modeling of multi-cracks on specimen's cross-section. The contribution of stress generated by ligaments to the critical stress at crack tip was obtained with this method, and then the analytical model of

Changes in Contact Area in Meniscus Horizontal Cleavage Tears Subjected to Repair and Resection.

Science.gov (United States)

Beamer, Brandon S; Walley, Kempland C; Okajima, Stephen; Manoukian, Ohan S; Perez-Viloria, Miguel; DeAngelis, Joseph P; Ramappa, Arun J; Nazarian, Ara

2017-03-01

To assess the changes in tibiofemoral contact pressure and contact area in human knees with a horizontal cleavage tear before and after treatment. Ten human cadaveric knees were tested. Pressure sensors were placed under the medial meniscus and the knees were loaded at twice the body weight for 20 cycles at 0°, 10°, and 20° of flexion. Contact area and pressure were recorded for the intact meniscus, the meniscus with a horizontal cleavage tear, after meniscal repair, after partial meniscectomy (single leaflet), and after subtotal meniscectomy (double leaflet). The presence of a horizontal cleavage tear significantly increased average peak contact pressure and reduced effective average tibiofemoral contact area at all flexion angles tested compared with the intact state (P contact pressure after creation of the horizontal cleavage tear. Repairing the horizontal cleavage tear restored peak contact pressures and areas to within 15% of baseline, statistically similar to the intact state at all angles tested (P contact pressure and reduced average contact area at all degrees of flexion compared with the intact state (P contact area and a significant elevation in contact pressure. These changes may accelerate joint degeneration. A suture-based repair of these horizontal cleavage tears returns the contact area and contact pressure to nearly normal, whereas both partial and subtotal meniscectomy lead to significant reductions in contact area and significant elevations in contact pressure within the knee. Repairing horizontal cleavage tears may lead to improved clinical outcomes by preserving meniscal tissue and the meniscal function. Understanding contact area and peak contact pressure resulting from differing strategies for treating horizontal cleavage tears will allow the surgeon to evaluate the best strategy for treating his or her patients who present with this meniscal pathology. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier

Oxidative cleavage of erucic acid for the synthesis of brassylic acid

Energy Technology Data Exchange (ETDEWEB)

Mohammed J. Nasrullah; Pooja Thapliyal; Erica N. Pfarr; Nicholas S. Dusek; Kristofer L. Schiele; James A. Bahr

2010-10-29

The main focus of this work is to synthesize Brassylic Acid (BA) using oxidative cleavage of Erucic Acid (EA). Crambe (Crambe abyssinica) is an industrial oilseed grown in North Dakota. Crambe has potential as an industrial fatty acid feedstock as a source of Erucic acid (EA). It has approximately 50-60 % of EA, a C{sub 22} monounsaturated fatty acid. Oxidative cleavage of unsaturated fatty acids derived from oilseeds produces long chain (9, 11, and 13 carbon atoms) dibasic and monobasic acids. These acids are known commercial feedstocks for the preparation of nylons, polyesters, waxes, surfactants, and perfumes. Other sources of EA are Rapeseed seed oil which 50-60 % of EA. Rapeseed is grown outside USA. The oxidative cleavage of EA was done using a high throughput parallel pressure reactor system. Kinetics of the reaction shows that BA yields reach a saturation at 12 hours. H{sub 2}WO{sub 4} was found to be the best catalyst for the oxidative cleavage of EA. High yields of BA were obtained at 80 C with bubbling of O{sub 2} or 10 bar of O{sub 2} for 12 hours.

Caspase-Dependent Apoptosis Induced by Telomere Cleavage and TRF2 Loss

Directory of Open Access Journals (Sweden)

Asha S. Multani

2000-07-01

Full Text Available Chromosomal abnormalities involving telomeric associations (TAs often precede replicative senescence and abnormal chromosome configurations. We report here that telomere cleavage following exposure to proapoptotic agents is an early event in apoptosis. Exposure of human and murine cancer cells to a variety of pro-apoptotic stimuli (staurosporine, thapsigargin, anti-Fas antibody, cancer chemotherapeutic agents resulted in telomere cleavage and aggregation, finally their extrusion from the nuclei. Telomere loss was associated with arrest of cells in G2/M phase and preceded DNA fragmentation. Telomere erosion and subsequent large-scale chromatin cleavage were inhibited by overexpression of the anti -apoptotic protein, bcl-2, two peptide caspase inhibitors (BACMK and zVADfmk, indicating that both events are regulated by caspase activation. The results demonstrate that telomere cleavage is an early chromatin alteration detected in various cancer cell lines leading to drug-induced apoptosis, suggest that this event contributes to mitotic catastrophe and induction of cell death. Results also suggest that the decrease of telomeric-repeat binding factor 2 (TRF2 may be the earliest event in the ara-C-induced telomere shortening, induction of endoreduplication and chromosomal fragmentation leading to cell death.

Structural and Biochemical Characterization of Organotin and Organolead Compounds Binding to the Organomercurial Lyase MerB Provide New Insights into Its Mechanism of Carbon–Metal Bond Cleavage

Energy Technology Data Exchange (ETDEWEB)

Wahba, Haytham M. [Département; Faculty; Stevenson, Michael J. [Department; Mansour, Ahmed [Département; Sygusch, Jurgen [Département; Wilcox, Dean E. [Department; Omichinski, James G. [Département

2017-01-03

The organomercurial lyase MerB has the unique ability to cleave carbon–Hg bonds, and structural studies indicate that three residues in the active site (C96, D99, and C159 in E. coli MerB) play important roles in the carbon–Hg bond cleavage. However, the role of each residue in carbon–metal bond cleavage has not been well-defined. To do so, we have structurally and biophysically characterized the interaction of MerB with a series of organotin and organolead compounds. Studies with two known inhibitors of MerB, dimethyltin (DMT) and triethyltin (TET), reveal that they inhibit by different mechanisms. In both cases the initial binding is to D99, but DMT subsequently binds to C96, which induces a conformation change in the active site. In contrast, diethyltin (DET) is a substrate for MerB and the SnIV product remains bound in the active site in a coordination similar to that of HgII following cleavage of organomercurial compounds. The results with analogous organolead compounds are similar in that trimethyllead (TML) is not cleaved and binds only to D99, whereas diethyllead (DEL) is a substrate and the PbIV product remains bound in the active site. Binding and cleavage is an exothermic reaction, while binding to D99 has negligible net heat flow. These results show that initial binding of organometallic compounds to MerB occurs at D99 followed, in some cases, by cleavage and loss of the organic moieties and binding of the metal ion product to C96, D99, and C159. The N-terminus of MerA is able to extract the bound PbVI but not the bound SnIV. These results suggest that MerB could be utilized for bioremediation applications, but certain organolead and organotin compounds may present an obstacle by inhibiting the enzyme.

Pressure modulates the self-cleavage step of the hairpin ribozyme

Science.gov (United States)

Schuabb, Caroline; Kumar, Narendra; Pataraia, Salome; Marx, Dominik; Winter, Roland

2017-03-01

The ability of certain RNAs, denoted as ribozymes, to not only store genetic information but also catalyse chemical reactions gave support to the RNA world hypothesis as a putative step in the development of early life on Earth. This, however, might have evolved under extreme environmental conditions, including the deep sea with pressures in the kbar regime. Here we study pressure-induced effects on the self-cleavage of hairpin ribozyme by following structural changes in real-time. Our results suggest that compression of the ribozyme leads to an accelerated transesterification reaction, being the self-cleavage step, although the overall process is retarded in the high-pressure regime. The results reveal that favourable interactions between the reaction site and neighbouring nucleobases are strengthened under pressure, resulting therefore in an accelerated self-cleavage step upon compression. These results suggest that properly engineered ribozymes may also act as piezophilic biocatalysts in addition to their hitherto known properties.

Ring-Expansion/Contraction Radical Crossover Reactions of Cyclic Alkoxyamines: A Mechanism for Ring Expansion-Controlled Radical Polymerization

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Atsushi Narumi

2018-06-01

Full Text Available Macrocyclic polymers present an important class of macromolecules, displaying the reduced radius of gyration or impossibility to entangle. A rare approach for their synthesis is the ring expansion-controlled radical “vinyl” polymerization, starting from a cyclic alkoxyamine. We here describe ring-expansion radical crossover reactions of cyclic alkoxyamines which run in parallel to chain-propagation reactions in the polymerization system. The radical crossover reactions extensively occurred at 105–125 °C, eventually producing high molecular weight polymers with multiple inherent dynamic covalent bonds (NOC bonds. A subsequent ring-contraction radical crossover reaction and the second ring-expansion radical crossover reaction are also described. The major products for the respective three stages were shown to possess cyclic morphologies by the molecular weight profiles and the residual ratios for the NOC bonds (φ in %. In particular, the high φ values ranging from ca. 80% to 98% were achieved for this cyclic alkoxyamine system. This result verifies the high availability of this system as a tool demonstrating the ring-expansion “vinyl” polymerization that allows them to produce macrocyclic polymers via a one-step vinyl polymerization.

WR stars with ring nebulae

International Nuclear Information System (INIS)

Tutukov, A.

1982-01-01

It is shown that most of usually apparently single nitrogen WR stars with ring emission nebulae around them (WN + Neb) are a probable product of the evolution of a massive close binary with initial masses of components exceeding approximately 20 solar masses. (Auth.)

Computational analysis and modeling of cleavage by the immunoproteasome and the constitutive proteasome

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Lafuente Esther M

2010-09-01

Full Text Available Abstract Background Proteasomes play a central role in the major histocompatibility class I (MHCI antigen processing pathway. They conduct the proteolytic degradation of proteins in the cytosol, generating the C-terminus of CD8 T cell epitopes and MHCI-peptide ligands (P1 residue of cleavage site. There are two types of proteasomes, the constitutive form, expressed in most cell types, and the immunoproteasome, which is constitutively expressed in mature dendritic cells. Protective CD8 T cell epitopes are likely generated by the immunoproteasome and the constitutive proteasome, and here we have modeled and analyzed the cleavage by these two proteases. Results We have modeled the immunoproteasome and proteasome cleavage sites upon two non-overlapping sets of peptides consisting of 553 CD8 T cell epitopes, naturally processed and restricted by human MHCI molecules, and 382 peptides eluted from human MHCI molecules, respectively, using N-grams. Cleavage models were generated considering different epitope and MHCI-eluted fragment lengths and the same number of C-terminal flanking residues. Models were evaluated in 5-fold cross-validation. Judging by the Mathew's Correlation Coefficient (MCC, optimal cleavage models for the proteasome (MCC = 0.43 ± 0.07 and the immunoproteasome (MCC = 0.36 ± 0.06 were obtained from 12-residue peptide fragments. Using an independent dataset consisting of 137 HIV1-specific CD8 T cell epitopes, the immunoproteasome and proteasome cleavage models achieved MCC values of 0.30 and 0.18, respectively, comparatively better than those achieved by related methods. Using ROC analyses, we have also shown that, combined with MHCI-peptide binding predictions, cleavage predictions by the immunoproteasome and proteasome models significantly increase the discovery rate of CD8 T cell epitopes restricted by different MHCI molecules, including A*0201, A*0301, A*2402, B*0702, B*2705. Conclusions We have developed models that are specific

Supported Catalysts Useful in Ring-Closing Metathesis, Cross Metathesis, and Ring-Opening Metathesis Polymerization

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Jakkrit Suriboot

2016-04-01

Full Text Available Ruthenium and molybdenum catalysts are widely used in synthesis of both small molecules and macromolecules. While major developments have led to new increasingly active catalysts that have high functional group compatibility and stereoselectivity, catalyst/product separation, catalyst recycling, and/or catalyst residue/product separation remain an issue in some applications of these catalysts. This review highlights some of the history of efforts to address these problems, first discussing the problem in the context of reactions like ring-closing metathesis and cross metathesis catalysis used in the synthesis of low molecular weight compounds. It then discusses in more detail progress in dealing with these issues in ring opening metathesis polymerization chemistry. Such approaches depend on a biphasic solid/liquid or liquid separation and can use either always biphasic or sometimes biphasic systems and approaches to this problem using insoluble inorganic supports, insoluble crosslinked polymeric organic supports, soluble polymeric supports, ionic liquids and fluorous phases are discussed.

Functional Groups Determine Biochar Properties (pH and EC as Studied by Two-Dimensional (13C NMR Correlation Spectroscopy.

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Xiaoming Li

Full Text Available While the properties of biochar are closely related to its functional groups, it is unclear under what conditions biochar develops its properties. In this study, two-dimensional (2D (13C nuclear magnetic resonance (NMR correlation spectroscopy was for the first time applied to investigate the development of functional groups and establish their relationship with biochar properties. The results showed that the agricultural biomass carbonized to biochars was a dehydroxylation/dehydrogenation and aromatization process, mainly involving the cleavage of O-alkylated carbons and anomeric O-C-O carbons in addition to the production of fused-ring aromatic structures and aromatic C-O groups. With increasing charring temperature, the mass cleavage of O-alkylated groups and anomeric O-C-O carbons occurred prior to the production of fused-ring aromatic structures. The regression analysis between functional groups and biochar properties (pH and electrical conductivity further demonstrated that the pH and electrical conductivity of rice straw derived biochars were mainly determined by fused-ring aromatic structures and anomeric O-C-O carbons, but the pH of rice bran derived biochars was determined by both fused-ring aromatic structures and aliphatic O-alkylated (HCOH carbons. In summary, this work suggests a novel tool for characterising the development of functional groups in biochars.

Radial cracks and fracture mechanism of radially oriented ring 2:17 type SmCo magnets

International Nuclear Information System (INIS)

Tian Jianjun; Pan Dean; Zhou Hao; Yin Fuzheng; Tao Siwu; Zhang Shengen; Qu Xuanhui

2009-01-01

Radially oriented ring 2:17 type SmCo magnets have different microstructure in the radial direction (easy magnetization) and axial direction (hard magnetization). The structure of the cross-section in radial direction is close-packed atomic plane, which shows cellular microstructure. The microstructure of the cross-section in axial direction consists of a mixture of rhombic microstructure and parallel lamella phases. So the magnets have obvious anisotropy of thermal expansion in different directions. The difference of the thermal expansion coefficients reaches the maximum value at 830-860 deg. C, which leads to radial cracks during quenching. The magnets have high brittlement because there are fewer slip systems in crystal structure. The fracture is brittle cleavage fracture.

On the temperature independence of statistical model parameters for cleavage fracture in ferritic steels

Science.gov (United States)

Qian, Guian; Lei, Wei-Sheng; Niffenegger, M.; González-Albuixech, V. F.

2018-04-01

The work relates to the effect of temperature on the model parameters in local approaches (LAs) to cleavage fracture. According to a recently developed LA model, the physical consensus of plastic deformation being a prerequisite to cleavage fracture enforces any LA model of cleavage fracture to observe initial yielding of a volume element as its threshold stress state to incur cleavage fracture in addition to the conventional practice of confining the fracture process zone within the plastic deformation zone. The physical consistency of the new LA model to the basic LA methodology and the differences between the new LA model and other existing models are interpreted. Then this new LA model is adopted to investigate the temperature dependence of LA model parameters using circumferentially notched round tensile specimens. With the published strength data as input, finite element (FE) calculation is conducted for elastic-perfectly plastic deformation and the realistic elastic-plastic hardening, respectively, to provide stress distributions for model calibration. The calibration results in temperature independent model parameters. This leads to the establishment of a 'master curve' characteristic to synchronise the correlation between the nominal strength and the corresponding cleavage fracture probability at different temperatures. This 'master curve' behaviour is verified by strength data from three different steels, providing a new path to calculate cleavage fracture probability with significantly reduced FE efforts.

Black rings

International Nuclear Information System (INIS)

Emparan, Roberto; Reall, Harvey S

2006-01-01

A black ring is a five-dimensional black hole with an event horizon of topology S 1 x S 2 . We provide an introduction to the description of black rings in general relativity and string theory. Novel aspects of the presentation include a new approach to constructing black ring coordinates and a critical review of black ring microscopics. (topical review)

The cleavage product of amyloid-β protein precursor sAβPPα modulates BAG3-dependent aggresome formation and enhances cellular proteasomal activity.

Science.gov (United States)

Renziehausen, Jana; Hiebel, Christof; Nagel, Heike; Kundu, Arpita; Kins, Stefan; Kögel, Donat; Behl, Christian; Hajieva, Parvana

2015-01-01

Alzheimer's disease (AD) is the major age-associated form of dementia characterized by gradual cognitive decline. Aberrant cleavage of the amyloid-β protein precursor (AβPP) is thought to play an important role in the pathology of this disease. Two principal AβPP processing pathways exist: amyloidogenic cleavage of AβPP resulting in production of the soluble N-terminal fragment sAβPPβ, amyloid-β (Aβ), which accumulates in AD brain, and the AβPP intracellular domain (AICD) sAβPPα, p3 and AICD are generated in the non-amyloidogenic pathway. Prevalence of amyloidogenic versus non-amyloidogenic processing leads to depletion of sAβPPα and an increase in Aβ. Although sAβPPα is a well-accepted neurotrophic protein, molecular effects of this fragment remains unknown. Different studies reported impaired protein degradation pathways in AD brain, pointing to a role of disturbed proteasomal activity in the pathogenesis of this disease. Here we studied the possible role of sAβPPα in Bag3-mediated selective macroautophagy and proteasomal degradation. Employing human IMR90 cells, HEK 293 cells, and primary neurons, we demonstrate that sAβPPα prevents the proteotoxic stress-induced increase of Bag3 at the protein and at the mRNA level indicating a transcriptional regulation. Intriguingly, p62 and LC3, two other key players of autophagy, were not affected. Moreover, the formation and the accumulation of disease-related protein aggregates were significantly reduced by sAβPPα. Interestingly, there was a significant increase of proteasomal activity by sAβPPα as demonstrated by using various proteasome substrates. Our findings demonstrate that sAβPPα modulates Bag3 expression, aggresome formation, and proteasomal activity, thereby providing first evidence for a function of sAβPPα in the regulation of proteostasis.

Effect of follicular diameter, time of first cleavage and H3K4 methylation on embryo production rates of Bos indicus cattle

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Paula Alvares Lunardelli

2016-10-01

Full Text Available This study aimed investigate the relationship between epigenetics, follicular diameter and cleavage speed, by evaluating the developmental potential and occurence of H3K4 monomethylation of early-, intermediate- and late-cleaving Bos indicus embryos from in vitro fertilized oocytes originating from follicles up to 2 mm in diameter or between 4 and 8 mm in diameter. Oocytes (n = 699 from small follicles (? 2 mm and 639 oocytes from large follicles (4-8 mm were punched from 1,982 Bos indicus’ slaughterhouse ovaries. After maturation and in vitro fertilization (IVF, the cultured embryos were separated into early (? 28 h post-IVF, intermediate (> 28 h and ? 34 h post-IVF and late (> 34 h and ? 54 h post-IVF cleavage groups. Blastocysts were subjected to an immunofluorescence assessment for H3K4me investigation. The blastocyst rate for large follicles (36.3% was higher than that for small follicles (22.9%, P < 0.05. In addition, blastocyst rates for early and intermediate cleavage groups (45.3% and 33.8%, respectively were higher than that for late cleavage group (13.5%, P < 0.05. The blastocysts from all groups displayed H3K4me staining by immunofluorescence, particularly intense in what seemed to be trophectoderm cells and weak or absent in cells seemingly from the inner cell mass. For the first time for indicus embryos, data from this study demonstrate that higher blastocyst embryo rates are obtained from embryos that cleave within 34 h after fertilization and from those produced from follicles of 4-8 mm in diameter, indicating a greater ability of these embryos to develop to the stage of embryonic preimplantation. This is the first article demonstrating the occurrence of H3K4me in cattle embryos; its presence in all the evaluated blastocysts suggests that this histone modification plays a key role in maintaining embryo viability at preimplantation stage.

Fractographic observations of cleavage initiation in the ductile-brittle transition region of a reactor-pressure-vessel steel

International Nuclear Information System (INIS)

Rosenfield, A.R.; Shetty, D.K.; Skidmore, A.J.

1983-01-01

This note reports the results of a fractographic study conducted on a group of 1T compact fracture toughness specimens of a heavy-section A508 steel denoted TSE6 tested in the ductile-brittle transition region (22 and 82 0 C). The fatigue-precracked specimens were loaded at a rapid rate (760 or 550 mm per second) to promote cleavage-crack growth and lower-bound toughness behavior. All specimens experienced unstable cleavage fracture prior to reaching a maximum in the load displacement curve. Some ductile crack growth occurred in half of the specimens. The objective of fractographic examinations was to understand the observed statistical variations in cleavage initiation by (a) locating the origins of unstable cleavage fracture in the vicinity of the fatigue-precrack or ductilerupture crack fronts, (b) identifying microstructural features associated with the triggering of cleavage, and (c) documenting characteristic fracture surface dimensions such as the extent of stable-crack growth prior to unstable cleavage (Δα) and the distance of the cleavage origin from the ductilerupture front, /chi/ (or fatigue-crack front when Δα = 0)

Sensitive and fast mutation detection by solid phase chemical cleavage

DEFF Research Database (Denmark)

Hansen, Lise Lotte; Justesen, Just; Kruse, Torben A

1996-01-01

We have developed a solid phase chemical cleavage method (SpCCM) for screening large DNA fragments for mutations. All reactions can be carried out in microtiterwells from the first amplification of the patient (or test) DNA through the search for mutations. The reaction time is significantly...... reduced compared to the conventional chemical cleavage method (CCM), and even by using a uniformly labelled probe, the exact position and nature of the mutation can be revealed. The SpCCM is suitable for automatization using a workstation to carry out the reactions and a fluorescent detection-based DNA...

On the formation and nature of quasi-cleavage fracture surfaces in hydrogen embrittled steels

Energy Technology Data Exchange (ETDEWEB)

Martin, May L.; Fenske, Jamey A.; Liu, Grace S.; Sofronis, Petros [University of Illinois, Dept. of Materials Science and Engineering, 1304 W. Green St., Urbana, IL 61801 (United States); Robertson, Ian M., E-mail: ianr@illinois.edu [University of Illinois, Dept. of Materials Science and Engineering, 1304 W. Green St., Urbana, IL 61801 (United States)

2011-02-15

Quasi-cleavage, a common feature of hydrogen-induced fracture surfaces, is generally taken as being cleavage-like but not along a known cleavage plane. Despite the frequency with which this surface is observed, the relationship to the underlying microstructure remains unknown. Through a combination of topographical reconstruction of secondary electron microscope fractographs and a transmission electron microscopy study of the microstructure from site-specific locations, it will be shown that the features on quasi-cleavage surfaces are ridges that can be correlated with sub-surface intense and highly localized deformation bands. It will be demonstrated that the fracture surface arises from the growth and coalescence of voids that initiate at and extend along slip band intersections. This mechanism and process is fully consistent with hydrogen enhancing and localizing plastic processes.

Variations in Ring Particle Cooling across Saturn's Rings with Cassini CIRS

Science.gov (United States)

Brooks, S. M.; Spilker, L. J.; Pilorz, S.; Edgington, S. G.; Déau, E.; Altobelli, N.

2010-12-01

Cassini's Composite Infrared Spectrometer has recorded over two million of spectra of Saturn's rings in the far infrared since arriving at Saturn in 2004. CIRS records far infrared radiation between 10 and 600 cm-1 ( 16.7 and 1000 μ {m} ) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermal emission from Saturn’s rings peaks in this wavelength range. Ring temperatures can be inferred from FP1 data. By tracking how ring temperatures vary, we can determine the thermal inertia of the rings. Previous studies have shown that the rings' thermal inertia, a measure of their response to changes in the thermal environment, varies from ring to ring. Thermal inertia can provide insight into the physical structure of Saturn's ring particles and their regoliths. Low thermal inertia and rapidly changing temperatures are suggestive of ring particles that have more porous or fluffy regoliths or that are riddled with cracks. Solid particles can be expected to have higher thermal inertias. Ferrari et al. (2005) fit thermal inertia values of 5218 {Jm)-2 {K}-1 {s}-1/2 to their B ring data and 6412 {Jm)-2 {K}-1 {s}-1/2 to their C ring data. In this work we focus on CIRS observations of the shadowed portion of Saturn's rings. The rings’ thermal budget is dominated by its absorption of solar radiation. As a result, ring particles abruptly cool as they traverse Saturn's shadow. From these shadow observations we can create cooling curves at specific locations across the rings. We will show that the rings' cooling curves and thus their thermal inertia vary not only from ring to ring, but by location within the individual rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

WYE-120318, a ring contraction product of methylnaltrexone, and structure revision of coniothyrione.

Science.gov (United States)

Kong, Fangming; Zhu, Tianmin; Pan, Weitao; Tsao, Russ; Pagano, Thomas G; Nguyen, Bao; Marquez, Brian

2012-12-01

A contracted ring degradation product, WYE-120318 (compound 2), was discovered during the development phase for methylnaltrexone bromide (compound 1) drug substance. The compound was isolated by high-performance liquid chromatography fractionation, and its structure was determined by spectroscopic data analyses. WYE-120318 is formed from methylnaltrexone through a benzyl-benzilic acid type rearrangement reaction to yield an α-hydroxy-cyclopentanecarboxylic acid substructure. The proposed structure and the formation mechanism are confirmed by the synthesis of WYE-120318 from methylnaltrexone (compound 1). A similar benzyl-benzilic acid type rearrangement reaction can be envisioned as the biological origin of remisporine A (compound 3), a naturally occurring cyclopentadienyl compound that autocatalytically dimerizes to remisporine B (compound 4). The structure of remisporine A was deduced from its dimer 4. Coniothyione (compound 5) can be considered as the first example of a stable natural product bearing the remisporine A skeleton. However, the regiochemistry of the chlorosubstitution in the coniothyrione structure needs to be revised to compound 6 on the basis of the nuclear magnetic resonance data and biogenesis analysis. Copyright © 2012 John Wiley & Sons, Ltd.

Capturing spiral radial growth of conifers using the superellipse to model tree-ring geometric shape.

Science.gov (United States)

Shi, Pei-Jian; Huang, Jian-Guo; Hui, Cang; Grissino-Mayer, Henri D; Tardif, Jacques C; Zhai, Li-Hong; Wang, Fu-Sheng; Li, Bai-Lian

2015-01-01

Tree-rings are often assumed to approximate a circular shape when estimating forest productivity and carbon dynamics. However, tree rings are rarely, if ever, circular, thereby possibly resulting in under- or over-estimation in forest productivity and carbon sequestration. Given the crucial role played by tree ring data in assessing forest productivity and carbon storage within a context of global change, it is particularly important that mathematical models adequately render cross-sectional area increment derived from tree rings. We modeled the geometric shape of tree rings using the superellipse equation and checked its validation based on the theoretical simulation and six actual cross sections collected from three conifers. We found that the superellipse better describes the geometric shape of tree rings than the circle commonly used. We showed that a spiral growth trend exists on the radial section over time, which might be closely related to spiral grain along the longitudinal axis. The superellipse generally had higher accuracy than the circle in predicting the basal area increment, resulting in an improved estimate for the basal area. The superellipse may allow better assessing forest productivity and carbon storage in terrestrial forest ecosystems.

Numerical modeling of ductile tearing effects on cleavage fracture toughness

International Nuclear Information System (INIS)

Dodds, R.H. Jr.; Tang, M.; Anderson, T.L.

1994-05-01

Experimental studies demonstrate a significant effect of specimen size, a/W ratio and prior ductile tearing on cleavage fracture toughness values (J c ) measured in the ductile-to-brittle transition region of ferritic materials. In the lower-transition region, cleavage fracture often occurs under conditions of large-scale yielding but without prior ductile crack extension. The increased toughness develops when plastic zones formed at the crack tip interact with nearby specimen surfaces which relaxes crack-tip constraint (stress triaxiality). In the mid-to-upper transition region, small amounts of ductile crack extension (often c -values. Previous work by the authors described a micromechanics fracture model to correct measured J c -values for the mechanistic effects of large-scale yielding. This new work extends the model to also include the influence of ductile crack extension prior to cleavage. The paper explores development of the new model, provides necessary graphs and procedures for its application and demonstrates the effects of the model on fracture data sets for two pressure vessel steels (A533B and A515)

Structure of the cleavage-activated prefusion form of the parainfluenza virus 5 fusion protein.

Science.gov (United States)

Welch, Brett D; Liu, Yuanyuan; Kors, Christopher A; Leser, George P; Jardetzky, Theodore S; Lamb, Robert A

2012-10-09

The paramyxovirus parainfluenza virus 5 (PIV5) enters cells by fusion of the viral envelope with the plasma membrane through the concerted action of the fusion (F) protein and the receptor binding protein hemagglutinin-neuraminidase. The F protein folds initially to form a trimeric metastable prefusion form that is triggered to undergo large-scale irreversible conformational changes to form the trimeric postfusion conformation. It is thought that F refolding couples the energy released with membrane fusion. The F protein is synthesized as a precursor (F0) that must be cleaved by a host protease to form a biologically active molecule, F1,F2. Cleavage of F protein is a prerequisite for fusion and virus infectivity. Cleavage creates a new N terminus on F1 that contains a hydrophobic region, known as the FP, which intercalates target membranes during F protein refolding. The crystal structure of the soluble ectodomain of the uncleaved form of PIV5 F is known; here we report the crystal structure of the cleavage-activated prefusion form of PIV5 F. The structure shows minimal movement of the residues adjacent to the protease cleavage site. Most of the hydrophobic FP residues are buried in the uncleaved F protein, and only F103 at the newly created N terminus becomes more solvent-accessible after cleavage. The conformational freedom of the charged arginine residues that compose the protease recognition site increases on cleavage of F protein.

Alternative loop rings

CERN Document Server

Goodaire, EG; Polcino Milies, C

1996-01-01

For the past ten years, alternative loop rings have intrigued mathematicians from a wide cross-section of modern algebra. As a consequence, the theory of alternative loop rings has grown tremendously. One of the main developments is the complete characterization of loops which have an alternative but not associative, loop ring. Furthermore, there is a very close relationship between the algebraic structures of loop rings and of group rings over 2-groups. Another major topic of research is the study of the unit loop of the integral loop ring. Here the interaction between loop rings and group ri

Primitivity and weak distributivity in near rings and matrix near rings

International Nuclear Information System (INIS)

Abbasi, S.J.

1993-08-01

This paper shows the structure of matrix near ring constructed over a weakly distributive and primative near ring. It is proved that a weakly distributive primitive near ring is a ring and the matrix near rings constructed over it is also a bag. (author). 14 refs

Critical cleavage fracture stress characterization of A508 nuclear pressure vessel steels

International Nuclear Information System (INIS)

Wu, Sujun; Jin, Huijin; Sun, Yanbin; Cao, Luowei

2014-01-01

The critical cleavage fracture stress of SA508 Gr.4N and SA508 Gr.3 low alloy reactor pressure vessel (RPV) steels was studied through the combination of experiments and finite element method (FEM) analysis. The results showed that the value of the local cleavage fracture stress, σ F , of SA508 Gr.4N steel was significantly higher than that of SA508 Gr.3 steel. Detailed microstructural analysis was carried out using FEGSEM which revealed much smaller grains, finer and more homogenous carbide particles formed in SA508 Gr.4N steel. Compared with the SA508 Gr.3 steel currently used in the nuclear industry, the SA508 Gr.4N steel possesses higher strength and notch toughness as well as improved cleavage fracture behavior, and is considered a better candidate RPV steel for the next generation nuclear reactors. - Highlights: • Critical cleavage fracture stress was calculated through experiments and FEM. • Effects of both grain and carbide particle sizes on σ F were discussed. • The SA508 Gr.4N steel is a better candidate for the next generation nuclear reactors

A set of simple cell processes is sufficient to model spiral cleavage.

Science.gov (United States)

Brun-Usan, Miguel; Marín-Riera, Miquel; Grande, Cristina; Truchado-Garcia, Marta; Salazar-Ciudad, Isaac

2017-01-01

During cleavage, different cellular processes cause the zygote to become partitioned into a set of cells with a specific spatial arrangement. These processes include the orientation of cell division according to: an animal-vegetal gradient; the main axis (Hertwig's rule) of the cell; and the contact areas between cells or the perpendicularity between consecutive cell divisions (Sachs' rule). Cell adhesion and cortical rotation have also been proposed to be involved in spiral cleavage. We use a computational model of cell and tissue biomechanics to account for the different existing hypotheses about how the specific spatial arrangement of cells in spiral cleavage arises during development. Cell polarization by an animal-vegetal gradient, a bias to perpendicularity between consecutive cell divisions (Sachs' rule), cortical rotation and cell adhesion, when combined, reproduce the spiral cleavage, whereas other combinations of processes cannot. Specifically, cortical rotation is necessary at the 8-cell stage to direct all micromeres in the same direction. By varying the relative strength of these processes, we reproduce the spatial arrangement of cells in the blastulae of seven different invertebrate species. © 2017. Published by The Company of Biologists Ltd.

Prion protein cleavage fragments regulate adult neural stem cell quiescence through redox modulation of mitochondrial fission and SOD2 expression.

Science.gov (United States)

Collins, Steven J; Tumpach, Carolin; Groveman, Bradley R; Drew, Simon C; Haigh, Cathryn L

2018-03-24

Neurogenesis continues in the post-developmental brain throughout life. The ability to stimulate the production of new neurones requires both quiescent and actively proliferating pools of neural stem cells (NSCs). Actively proliferating NSCs ensure that neurogenic demand can be met, whilst the quiescent pool makes certain NSC reserves do not become depleted. The processes preserving the NSC quiescent pool are only just beginning to be defined. Herein, we identify a switch between NSC proliferation and quiescence through changing intracellular redox signalling. We show that N-terminal post-translational cleavage products of the prion protein (PrP) induce a quiescent state, halting NSC cellular growth, migration, and neurite outgrowth. Quiescence is initiated by the PrP cleavage products through reducing intracellular levels of reactive oxygen species. First, inhibition of redox signalling results in increased mitochondrial fission, which rapidly signals quiescence. Thereafter, quiescence is maintained through downstream increases in the expression and activity of superoxide dismutase-2 that reduces mitochondrial superoxide. We further observe that PrP is predominantly cleaved in quiescent NSCs indicating a homeostatic role for this cascade. Our findings provide new insight into the regulation of NSC quiescence, which potentially could influence brain health throughout adult life.

Isomorphism Theorem on Vector Spaces over a Ring

Directory of Open Access Journals (Sweden)

Futa Yuichi

2017-10-01

Full Text Available In this article, we formalize in the Mizar system [1, 4] some properties of vector spaces over a ring. We formally prove the first isomorphism theorem of vector spaces over a ring. We also formalize the product space of vector spaces. ℤ-modules are useful for lattice problems such as LLL (Lenstra, Lenstra and Lovász [5] base reduction algorithm and cryptographic systems [6, 2].

Boron-doped diamond electrodes for the electrochemical oxidation and cleavage of peptides.

Science.gov (United States)

Roeser, Julien; Alting, Niels F A; Permentier, Hjalmar P; Bruins, Andries P; Bischoff, Rainer

2013-07-16

Electrochemical oxidation of peptides and proteins is traditionally performed on carbon-based electrodes. Adsorption caused by the affinity of hydrophobic and aromatic amino acids toward these surfaces leads to electrode fouling. We compared the performance of boron-doped diamond (BDD) and glassy carbon (GC) electrodes for the electrochemical oxidation and cleavage of peptides. An optimal working potential of 2000 mV was chosen to ensure oxidation of peptides on BDD by electron transfer processes only. Oxidation by electrogenerated OH radicals took place above 2500 mV on BDD, which is undesirable if cleavage of a peptide is to be achieved. BDD showed improved cleavage yield and reduced adsorption for a set of small peptides, some of which had been previously shown to undergo electrochemical cleavage C-terminal to tyrosine (Tyr) and tryptophan (Trp) on porous carbon electrodes. Repeated oxidation with BDD electrodes resulted in progressively lower conversion yields due to a change in surface termination. Cathodic pretreatment of BDD at a negative potential in an acidic environment successfully regenerated the electrode surface and allowed for repeatable reactions over extended periods of time. BDD electrodes are a promising alternative to GC electrodes in terms of reduced adsorption and fouling and the possibility to regenerate them for consistent high-yield electrochemical cleavage of peptides. The fact that OH-radicals can be produced by anodic oxidation of water at elevated positive potentials is an additional advantage as they allow another set of oxidative reactions in analogy to the Fenton reaction, thus widening the scope of electrochemistry in protein and peptide chemistry and analytics.

Cleavage mechanoluminescence in elemental and III-V semiconductors

International Nuclear Information System (INIS)

Chandra, B.P.; Patel, R.P.; Gour, Anubha S.; Chandra, V.K.; Gupta, R.K.

2003-01-01

The present paper reports the theory of mechanoluminescence (ML) produced during cleavage of elemental and III-V semiconductors. It seems that the formation of crack-induced localized states is responsible for the ML excitation produced during the cleavage of elemental and III-V semiconductors. According to this mechanism, as the atoms are drawn away from each other in an advancing crack tip, the decreasing wave function overlap across the crack may result in localized states which is associated with increasing electron energy. If the energy of these localized states approach that of the conduction band, transition to the conduction band via tunnelling would be possible, creating minority carriers, and consequently the electron-hole recombination may give rise to mechanoluminescence. When an elemental or III-V semiconductor is cleaved, initially the ML intensity increases with time, attains a peak value I m at the time t m corresponding to completion of the cleavage of the semiconductor, and then it decreases following power law decay. Expressions are derived for the ML intensity I m corresponding to the peak of the ML intensity versus time curve and for the total ML intensity I T . It is shown that both I m and I T should increase directly with the area of the newly created surfaces of the crystals. From the measurements of the ML intensity, the velocity of crack propagation in material can be determined by using the relation v=H/t m

Implementation of a combinatorial cleavage and deprotection scheme

DEFF Research Database (Denmark)

Nielsen, John; Rasmussen, Palle H.

1996-01-01

Phthalhydrazide libraries are synthesized in solution from substituted hydrazines and phthalimides in several different library formats including single compounds, indexed sub-libraries and a full library. When carried out during solid-phase synthesis, this combinatorial cleavage and deprotection...

Interaction of ring dark solitons with ring impurities in Bose-Einstein condensates

International Nuclear Information System (INIS)

Xue Jukui

2005-01-01

The interaction of ring dark solitons/vortexes with the ring-shaped repulsive and attractive impurities in two-dimensional Bose-Einstein condensates is investigated numerically. Very rich interaction phenomena are obtained, i.e., not only the interaction between the ring soliton and the impurity, but also the interaction between vortexes and the impurity. The interaction characters, i.e., snaking of ring soliton, quasitrapping or reflection of ring soliton and vortexes by the impurity, strongly depend on initial ring soliton velocity, impurity strength, initial position of ring soliton and impurity. The numerical results also reveal that ring dark solitons/vortexes can be trapped and dragged by an adiabatically moving attractive ring impurity

Oxidative C-C bond cleavage of 1,2-diols by silver(II)

International Nuclear Information System (INIS)

Kumar, A.

1981-01-01

Oxidation of ethylene glycol and related compounds by Ag(II) has been investigated. Complexation of these substrates by Ag(II) precedes their oxidation. Oxidation occurs through electron transfer from an OH group to the Ag(II) within the complex resulting in the formation of alkoxyl-type radicals. The radicals thus formed undergo β-scission to give cleavage products. For ethylene glycol a complexation rate 1.3 x 10 6 M -1 s -1 and oxidation rate approx. 3 x 10 3 s -1 were observed. A general trend for the type of the substrates which would undergo C-C bond scission by Ag(II) is discussed

Report of the New Rings Study Group

Energy Technology Data Exchange (ETDEWEB)

Holmes, S.D.; Dugan, G.; Marriner, J.

1987-10-19

We have taken the approach here of trying to understand both the feasibility and practicality of varied options for new rings at Fermilab, rather than trying to produce a single detailed design. In other words, this document is not a design report and should not be construed as such. Our perception of the potential needs for new rings (in order of priority) is as follows: Antiproton Storage and/or Recovery: A facility for storing up to 4 x 10/sup 12/ antiprotons is needed. Recovery of antiprotons from the collider becomes a viable option if the luminosity is indeed dominated by emittance dilution rather than beam loss. New or Post-Booster: The goal here would be to inject into the existing Main Ring above transition. Improved performance of the Main Ring would be anticipated. New Main Ring: Advantages would include better emittance preservation, a faster cycle time for antiproton production, and the removal of interference/backgrounds at the B0 and D0 detectors. We discuss in this paper various scenarios based on one or more combinations of the above possibilities. 14 figs., 10 tabs.

Report of the New Rings Study Group

International Nuclear Information System (INIS)

Holmes, S.D.; Dugan, G.; Marriner, J.

1987-01-01

We have taken the approach here of trying to understand both the feasibility and practicality of varied options for new rings at Fermilab, rather than trying to produce a single detailed design. In other words, this document is not a design report and should not be construed as such. Our perception of the potential needs for new rings (in order of priority) is as follows: Antiproton Storage and/or Recovery: A facility for storing up to 4 x 10 12 antiprotons is needed. Recovery of antiprotons from the collider becomes a viable option if the luminosity is indeed dominated by emittance dilution rather than beam loss. New or Post-Booster: The goal here would be to inject into the existing Main Ring above transition. Improved performance of the Main Ring would be anticipated. New Main Ring: Advantages would include better emittance preservation, a faster cycle time for antiproton production, and the removal of interference/backgrounds at the B0 and D0 detectors. We discuss in this paper various scenarios based on one or more combinations of the above possibilities. 14 figs., 10 tabs

Cleavage and synthesis function of high and low redox potential laccases towards 4-morpholinoaniline and aminated as well as chlorinated phenols.

Science.gov (United States)

Hahn, Veronika; Mikolasch, Annett; Schauer, Frieder

2014-02-01

Laccases are able to mediate both cleavage and synthesis processes. The basis for this dual reaction capability lies in the property of the enzyme laccase to oxidize phenolic, and to some extent non-phenolic substances, to reactive radicals which can undergo on the one hand separations of small substitutents or large molecule parts from the parent compound and on the other hand coupling reactions with other radicals or molecules which are not themselves oxidizable by laccase. The cleavage of the non-phenolic compound 4-morpholinoaniline as well as the deamination of 4-aminophenol and the dechlorination of 4-chlorophenol resulted in the formation of 1,4-hydroquinone which is immediately oxidized by laccase to 1,4-benzoquinone. The formation of the 1,4-hydroquinone/1,4-benzoquinone is the rate limiting step for the synthesis of the heteromolecular dimers and trimers composed of 1,4-benzoquinone and one or two molecules of morpholine. In addition to the synthesis of new compounds from the cleavage products, 4-morpholinoaniline polymerized probably via azo groups and C-N bonds to a homomolecular dimer and trimer. Similarities and differences in cleavage and synthesis reactions catalyzed by the low redox potential laccase of Myceliophthora thermophila (0.46 V) and the high redox potential laccase of Pycnoporus cinnabarinus (0.79 V) were determined. In addition, the dependency of the cleavage and synthesis efficiencies on the (a) structure and redox potential of the laccase, (b) structure and redox potential of the substrate, (c) pH value of the buffer used, (d) incubation temperature, (e) solvent concentration, and (f) laccase activity is discussed in general.

Mutation in Spike Protein Cleavage Site and Pathogenesis of Feline Coronavirus

Science.gov (United States)

Licitra, Beth N.; Millet, Jean K.; Regan, Andrew D.; Hamilton, Brian S.; Rinaldi, Vera D.; Duhamel, Gerald E.

2013-01-01

Feline coronaviruses (FCoV) exist as 2 biotypes: feline enteric coronavirus (FECV) and feline infectious peritonitis virus (FIPV). FECV causes subclinical infections; FIPV causes feline infectious peritonitis (FIP), a systemic and fatal disease. It is thought that mutations in FECV enable infection of macrophages, causing FIP. However, the molecular basis for this biotype switch is unknown. We examined a furin cleavage site in the region between receptor-binding (S1) and fusion (S2) domains of the spike of serotype 1 FCoV. FECV sequences were compared with FIPV sequences. All FECVs had a conserved furin cleavage motif. For FIPV, there was a correlation with the disease and >1 substitution in the S1/S2 motif. Fluorogenic peptide assays confirmed that the substitutions modulate furin cleavage. We document a functionally relevant S1/S2 mutation that arises when FIP develops in a cat. These insights into FIP pathogenesis may be useful in development of diagnostic, prevention, and treatment measures against coronaviruses. PMID:23763835

Mechanism of the Glycosidic Bond Cleavage of Mismatched Thymine in Human Thymine DNA Glycosylase Revealed by Classical Molecular Dynamics and Quantum Mechanical/Molecular Mechanical Calculations.

Science.gov (United States)

Kanaan, Natalia; Crehuet, Ramon; Imhof, Petra

2015-09-24

Base excision of mismatched or damaged nucleotides catalyzed by glycosylase enzymes is the first step of the base excision repair system, a machinery preserving the integrity of DNA. Thymine DNA glycosylase recognizes and removes mismatched thymine by cleaving the C1'-N1 bond between the base and the sugar ring. Our quantum mechanical/molecular mechanical calculations of this reaction in human thymine DNA glycosylase reveal a requirement for a positive charge in the active site to facilitate C1'-N1 bond scission: protonation of His151 significantly lowers the free energy barrier for C1'-N1 bond dissociation compared to the situation with neutral His151. Shuttling a proton from His151 to the thymine base further reduces the activation free energy for glycosidic bond cleavage. Classical molecular dynamics simulations of the H151A mutant suggest that the mutation to the smaller, neutral, residue increases the water accessibility of the thymine base, rendering direct proton transfer from the bulk feasible. Quantum mechanical/molecular mechanical calculations of the glycosidic bond cleavage reaction in the H151A mutant show that the activation free energy is slightly lower than in the wild-type enzyme, explaining the experimentally observed higher reaction rates in this mutant.

Structural and functional characterization of cleavage and inactivation of human serine protease inhibitors by the bacterial SPATE protease EspPα from enterohemorrhagic E. coli.

Directory of Open Access Journals (Sweden)

André Weiss

Full Text Available EspPα and EspI are serine protease autotransporters found in enterohemorrhagic Escherichia coli. They both belong to the SPATE autotransporter family and are believed to contribute to pathogenicity via proteolytic cleavage and inactivation of different key host proteins during infection. Here, we describe the specific cleavage and functional inactivation of serine protease inhibitors (serpins by EspPα and compare this activity with the related SPATE EspI. Serpins are structurally related proteins that regulate vital protease cascades, such as blood coagulation and inflammatory host response. For the rapid determination of serpin cleavage sites, we applied direct MALDI-TOF-MS or ESI-FTMS analysis of coincubations of serpins and SPATE proteases and confirmed observed cleavage positions using in-gel-digest of SDS-PAGE-separated degradation products. Activities of both serpin and SPATE protease were assessed in a newly developed photometrical assay using chromogenic peptide substrates. EspPα cleaved the serpins α1-protease inhibitor (α1-PI, α1-antichymotrypsin, angiotensinogen, and α2-antiplasmin. Serpin cleavage led to loss of inhibitory function as demonstrated for α1-PI while EspPα activity was not affected. Notably, EspPα showed pronounced specificity and cleaved procoagulatory serpins such as α2-antiplasmin while the anticoagulatory antithrombin III was not affected. Together with recently published research, this underlines the interference of EspPα with hemostasis or inflammatory responses during infection, while the observed interaction of EspI with serpins is likely to be not physiologically relevant. EspPα-mediated serpin cleavage occurred always in flexible loops, indicating that this structural motif might be required for substrate recognition.

Weierstrass preparation and division theorems for the ring of germs of superanalytic functions

International Nuclear Information System (INIS)

Yankov, C.L.

1989-11-01

The aim of this paper is to show that Weierstrass preparation and division theorems hold for the ring of germs of superanalytic functions at a given point. This ring is the tensor product of the ring of germs of analytic functions at that point and a finite-dimensional complex Grassmann algebra. 7 refs

Yeast ribonuclease III uses a network of multiple hydrogen bonds for RNA binding and cleavage.

Science.gov (United States)

Lavoie, Mathieu; Abou Elela, Sherif

2008-08-19

Members of the bacterial RNase III family recognize a variety of short structured RNAs with few common features. It is not clear how this group of enzymes supports high cleavage fidelity while maintaining a broad base of substrates. Here we show that the yeast orthologue of RNase III (Rnt1p) uses a network of 2'-OH-dependent interactions to recognize substrates with different structures. We designed a series of bipartite substrates permitting the distinction between binding and cleavage defects. Each substrate was engineered to carry a single or multiple 2'- O-methyl or 2'-fluoro ribonucleotide substitutions to prevent the formation of hydrogen bonds with a specific nucleotide or group of nucleotides. Interestingly, introduction of 2'- O-methyl ribonucleotides near the cleavage site increased the rate of catalysis, indicating that 2'-OH are not required for cleavage. Substitution of nucleotides in known Rnt1p binding site with 2'- O-methyl ribonucleotides inhibited cleavage while single 2'-fluoro ribonucleotide substitutions did not. This indicates that while no single 2'-OH is essential for Rnt1p cleavage, small changes in the substrate structure are not tolerated. Strikingly, several nucleotide substitutions greatly increased the substrate dissociation constant with little or no effect on the Michaelis-Menten constant or rate of catalysis. Together, the results indicate that Rnt1p uses a network of nucleotide interactions to identify its substrate and support two distinct modes of binding. One mode is primarily mediated by the dsRNA binding domain and leads to the formation of stable RNA/protein complex, while the other requires the presence of the nuclease and N-terminal domains and leads to RNA cleavage.

Rings in drugs.

Science.gov (United States)

Taylor, Richard D; MacCoss, Malcolm; Lawson, Alastair D G

2014-07-24

We have analyzed the rings, ring systems, and frameworks in drugs listed in the FDA Orange Book to understand the frequency, timelines, molecular property space, and the application of these rings in different therapeutic areas and target classes. This analysis shows that there are only 351 ring systems and 1197 frameworks in drugs that came onto the market before 2013. Furthermore, on average six new ring systems enter drug space each year and approximately 28% of new drugs contain a new ring system. Moreover, it is very unusual for a drug to contain more than one new ring system and the majority of the most frequently used ring systems (83%) were first used in drugs developed prior to 1983. These observations give insight into the chemical novelty of drugs and potentially efficient ways to assess compound libraries and develop compounds from hit identification to lead optimization and beyond.

Project of the compact superconducting storage ring Siberia-SM

Energy Technology Data Exchange (ETDEWEB)

Anashin, V V; Arbuzov, V S; Blinov, G A; Veshcherevich, V G; Vobly, P D; Gorniker, E I; Zinevich, N I; Zinin, E I; Zubkov, N I; Kiselev, V A; Kollerov, E P; Kulipanov, G N; Matveev, Yu G; Medvedko, A S; Mezentsev, N A; Morgunov, L G; Petrov, V M; Petrov, S P; Repkov, V V; Roenko, V A; Skrinsky, A N; Sukhanov, S V; Tokarev, Yu I; Trakhtenberg, E M [AN SSSR, Novosibirsk. Inst. Yadernoj Fiziki

1989-10-10

In the last decade researches dealing with the creation of technology for X-ray lithography and for appropriate production equipment have been performed in many countries. The basic aim of these works is to provide a mass production of inexpensive devices with submicron structures (0.7-0.1 {mu}m). Bringing X-ray lithographic technology into commercial practice necessitates to design and build a dedicated SR source for the electronic industry. The use of superconducting bending magnets with 40-70 kG field strength enables the storage ring circumference to be reduced by a factor of 2-5 and the injection energy by a factor of 3-4 as compared to the conventional designs of storage rings. In the present paper we consider a storage ring which was designed for a maximum energy of 600 MeV, with 60 kG field strength in its bending magnets and 10 m circumference. The critical SR wavelength is 8.6 A. The electrons are injected into the storage ring at 50-60 MeV and the maximum stored current is assumed to be equal to 0.3 A. (orig.).

Tomato carotenoid cleavage dioxygenases 1A and 1B: Relaxed double bond specificity leads to a plenitude of dialdehydes, mono-apocarotenoids and isoprenoid volatiles

KAUST Repository

Ilg, Andrea; Bruno, Mark; Beyer, Peter; Al-Babili, Salim

2014-01-01

The biosynthetic processes leading to many of the isoprenoid volatiles released by tomato fruits are still unknown, though previous reports suggested a clear correlation with the carotenoids contained within the fruit. In this study, we investigated the activity of the tomato (Solanum lycopersicum) carotenoid cleavage dioxygenase (SlCCD1B), which is highly expressed in fruits, and of its homolog SlCCD1A. Using in vitro assays performed with purified recombinant enzymes and by analyzing products formed by the two enzymes in carotene-accumulating Escherichia coli strains, we demonstrate that SlCCD1A and, to a larger extent, SlCCD1B, have a very relaxed specificity for both substrate and cleavage site, mediating the oxidative cleavage of cis- and all-. trans-carotenoids as well as of different apocarotenoids at many more double bonds than previously reported. This activity gives rise to a plenitude of volatiles, mono-apocarotenoids and dialdehyde products, including cis-pseudoionone, neral, geranial, and farnesylacetone. Our results provide a direct evidence for a carotenoid origin of these compounds and point to CCD1s as the enzymes catalyzing the formation of the vast majority of tomato isoprenoid volatiles, many of which are aroma constituents. © 2014 The Authors.

Tomato carotenoid cleavage dioxygenases 1A and 1B: Relaxed double bond specificity leads to a plenitude of dialdehydes, mono-apocarotenoids and isoprenoid volatiles

KAUST Repository

Ilg, Andrea

2014-06-25

The biosynthetic processes leading to many of the isoprenoid volatiles released by tomato fruits are still unknown, though previous reports suggested a clear correlation with the carotenoids contained within the fruit. In this study, we investigated the activity of the tomato (Solanum lycopersicum) carotenoid cleavage dioxygenase (SlCCD1B), which is highly expressed in fruits, and of its homolog SlCCD1A. Using in vitro assays performed with purified recombinant enzymes and by analyzing products formed by the two enzymes in carotene-accumulating Escherichia coli strains, we demonstrate that SlCCD1A and, to a larger extent, SlCCD1B, have a very relaxed specificity for both substrate and cleavage site, mediating the oxidative cleavage of cis- and all-. trans-carotenoids as well as of different apocarotenoids at many more double bonds than previously reported. This activity gives rise to a plenitude of volatiles, mono-apocarotenoids and dialdehyde products, including cis-pseudoionone, neral, geranial, and farnesylacetone. Our results provide a direct evidence for a carotenoid origin of these compounds and point to CCD1s as the enzymes catalyzing the formation of the vast majority of tomato isoprenoid volatiles, many of which are aroma constituents. © 2014 The Authors.

Tomato carotenoid cleavage dioxygenases 1A and 1B: Relaxed double bond specificity leads to a plenitude of dialdehydes, mono-apocarotenoids and isoprenoid volatiles

Directory of Open Access Journals (Sweden)

Andrea Ilg

2014-01-01

Full Text Available The biosynthetic processes leading to many of the isoprenoid volatiles released by tomato fruits are still unknown, though previous reports suggested a clear correlation with the carotenoids contained within the fruit. In this study, we investigated the activity of the tomato (Solanum lycopersicum carotenoid cleavage dioxygenase (SlCCD1B, which is highly expressed in fruits, and of its homolog SlCCD1A. Using in vitro assays performed with purified recombinant enzymes and by analyzing products formed by the two enzymes in carotene-accumulating Escherichia coli strains, we demonstrate that SlCCD1A and, to a larger extent, SlCCD1B, have a very relaxed specificity for both substrate and cleavage site, mediating the oxidative cleavage of cis- and all-trans-carotenoids as well as of different apocarotenoids at many more double bonds than previously reported. This activity gives rise to a plenitude of volatiles, mono-apocarotenoids and dialdehyde products, including cis-pseudoionone, neral, geranial, and farnesylacetone. Our results provide a direct evidence for a carotenoid origin of these compounds and point to CCD1s as the enzymes catalyzing the formation of the vast majority of tomato isoprenoid volatiles, many of which are aroma constituents.

Vaginal health in contraceptive vaginal ring users - A review.

Science.gov (United States)

Lete, Iñaki; Cuesta, María C; Marín, Juan M; Guerra, Sandra

2013-08-01

To provide an overview of the available data from clinical studies of vaginal conditions in women who use a vaginal ring as a contraceptive. A systematic review of the literature. Millions of women have already used the ethylene vinyl acetate vaginal ring that releases ethinylestradiol and etonogestrel for contraception. Because of its small size, more than four out of five women using the ring report that they do not feel it, even during sexual intercourse. No colposcopic or cytological changes have been observed in users, although approximately 10% have increased vaginal discharge. While in vitro studies have shown adhesion of Candida yeasts to the vaginal ring surface, clinical studies have not demonstrated a greater incidence of Candida infections compared to users of equivalent oral contraceptives. Some clinical studies suggest a lower incidence of bacterial vaginosis. No interaction exists between concomitant use of the vaginal ring and other drugs or products for vaginal use. The use of a contraceptive vaginal ring does not alter the vaginal ecosystem and therefore does not substantially affect vaginal health.

Development of dapivirine vaginal ring for HIV prevention.

Science.gov (United States)

Devlin, Bríd; Nuttall, Jeremy; Wilder, Susan; Woodsong, Cynthia; Rosenberg, Zeda

2013-12-01

In the continuing effort to develop effective HIV prevention methods for women, a vaginal ring containing the non-nucleoside reverse transcriptase inhibitor dapivirine is currently being tested in two safety and efficacy trials. This paper reviews dapivirine ring's pipeline development process, including efforts to determine safe and effective dosing levels as well as identify delivery platforms with the greatest likelihood of success for correct and consistent use. Dapivirine gel and other formulations were developed and tested in preclinical and clinical studies. Multiple vaginal ring prototypes were also tested, resulting in the current ring design as well as additional designs under consideration for future testing. Efficacy results from clinical trials are expected in 2015. Through ongoing consultations with national regulatory authorities, licensure requirements for dapivirine vaginal ring approval have been defined. This article is based on a presentation at the "Product Development Workshop 2013: HIV and Multipurpose Prevention Technologies," held in Arlington, Virginia on February 21-22, 2013. It forms part of a special supplement to Antiviral Research. Copyright © 2013 Elsevier B.V. All rights reserved.

Photochemically promoted bond-cleavage and -capture in a diazomethane derivative of a triamidoamine uranium(IV) complex

Energy Technology Data Exchange (ETDEWEB)

Gardner, Benedict M.; Patel, Dipti; Lewis, William; Blake, Alexander J.; Liddle, Stephen T. [School of Chemistry, University of Nottingham (United Kingdom)

2011-10-24

Photolysis of [U(tren{sup TMS})(μ-N(SiMe{sub 3})NC)]{sub 2} results in multiple bond cleavage and capture to give a well-defined product [U{N(CH_2CH_2NSiMe_3)_2(μ-CH_2CH_2N-C≡N)}{N(SiMe_3)_2}]{sub 2}. This transformation has no precedent in diazoalkane chemistry and is not thermally accessible. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Pyrexia's effect on the CBG-cortisol thermocouple, rather than CBG cleavage, elevates the acute free cortisol response to TNF-α in humans

DEFF Research Database (Denmark)

Nenke, Marni Anne; Nielsen, Signe Tellerup; Lehrskov, Louise Lang

2017-01-01

an inflammatory stimulus is unknown. Hence our aim was to determine the immediate effect of the key pro-inflammatory cytokine TNF-α on CBG levels and cleavage. We performed a crossover study of 12 healthy males receiving a TNF-α versus saline infusion, measuring total CBG, haCBG, laCBG and free and total cortisol...... hourly for 6 h. There was no change in total CBG or haCBG levels in the first 6 h of inflammation between the groups, suggesting that CBG cleavage is not activated nor is hepatic CBG production affected by TNF-α in this time frame. There was an early increase in the ratio of free:total cortisol...

Compartmental transport model of microbicide delivery by an intravaginal ring

Science.gov (United States)

Geonnotti, Anthony R.; Katz, David F.

2010-01-01

Topical antimicrobials, or microbicides, are being developed to prevent HIV transmission through local, mucosal delivery of antiviral compounds. While hydrogel vehicles deliver the majority of current microbicide products, intravaginal rings (IVRs) are an alternative microbicide modality in preclinical development. IVRs provide a long-term dosing alternative to hydrogel use, and might provide improved user adherence. IVR efficacy requires sustained delivery of antiviral compounds to the entire vaginal compartment. A two-dimensional, compartmental vaginal drug transport model was created to evaluate the delivery of drugs from an intravaginal ring. The model utilized MRI-derived ring geometry and location, experimentally defined ring fluxes and vaginal fluid velocities, and biophysically relevant transport theory. Model outputs indicated the presence of potentially inhibitory concentrations of antiviral compounds along the entire vaginal canal within 24 hours following IVR insertion. Distributions of inhibitory concentrations of antiviral compounds were substantially influenced by vaginal fluid flow and production, while showing little change due to changes in diffusion coefficients or ring fluxes. Additionally, model results were predictive of in vivo concentrations obtained in clinical trials. Overall, this analysis initiates a mechanistic computational framework, heretofore missing, to understand and evaluate the potential of IVRs for effective delivery of antiviral compounds. PMID:20222027

Polycystin-1 C-terminal Cleavage Is Modulated by Polycystin-2 Expression*

Science.gov (United States)

Bertuccio, Claudia A.; Chapin, Hannah C.; Cai, Yiqiang; Mistry, Kavita; Chauvet, Veronique; Somlo, Stefan; Caplan, Michael J.

2009-01-01

Autosomal dominant polycystic kidney disease is caused by mutations in the genes encoding polycystin-1 (PC-1) and polycystin-2 (PC-2). PC-1 cleavage releases its cytoplasmic C-terminal tail (CTT), which enters the nucleus. To determine whether PC-1 CTT cleavage is influenced by PC-2, a quantitative cleavage assay was utilized, in which the DNA binding and activation domains of Gal4 and VP16, respectively, were appended to PC-1 downstream of its CTT domain (PKDgalvp). Cells cotransfected with the resultant PKDgalvp fusion protein and PC-2 showed an increase in luciferase activity and in CTT expression, indicating that the C-terminal tail of PC-1 is cleaved and enters the nucleus. To assess whether CTT cleavage depends upon Ca2+ signaling, cells transfected with PKDgalvp alone or together with PC-2 were incubated with several agents that alter intracellular Ca2+ concentrations. PC-2 enhancement of luciferase activity was not altered by any of these treatments. Using a series of PC-2 C-terminal truncated mutations, we identified a portion of the PC-2 protein that is required to stimulate PC-1 CTT accumulation. These data demonstrate that release of the CTT from PC-1 is influenced and stabilized by PC-2. This effect is independent of Ca2+ but is regulated by sequences contained within the PC-2 C-terminal tail, suggesting a mechanism through which PC-1 and PC-2 may modulate a novel signaling pathway. PMID:19491093

Functional roles of the pepper RING finger protein gene, CaRING1, in abscisic acid signaling and dehydration tolerance.

Science.gov (United States)

Lim, Chae Woo; Hwang, Byung Kook; Lee, Sung Chul

2015-09-01

Plants are constantly exposed to a variety of biotic and abiotic stresses, which include pathogens and conditions of high salinity, low temperature, and drought. Abscisic acid (ABA) is a major plant hormone involved in signal transduction pathways that mediate the defense response of plants to abiotic stress. Previously, we isolated Ring finger protein gene (CaRING1) from pepper (Capsicum annuum), which is associated with resistance to bacterial pathogens, accompanied by hypersensitive cell death. Here, we report a new function of the CaRING1 gene product in the ABA-mediated defense responses of plants to dehydration stress. The expression of the CaRING1 gene was induced in pepper leaves treated with ABA or exposed to dehydration or NaCl. Virus-induced gene silencing of CaRING1 in pepper plants exhibited low degree of ABA-induced stomatal closure and high levels of transpirational water loss in dehydrated leaves. These led to be more vulnerable to dehydration stress in CaRING1-silenced pepper than in the control pepper, accompanied by reduction of ABA-regulated gene expression and low accumulation of ABA and H2O2. In contrast, CaRING1-overexpressing transgenic plants showed enhanced sensitivity to ABA during the seedling growth and establishment. These plants were also more tolerant to dehydration stress than the wild-type plants because of high ABA accumulation, enhanced stomatal closure and increased expression of stress-responsive genes. Together, these results suggest that the CaRING1 acts as positive factor for dehydration tolerance in Arabidopsis by modulating ABA biosynthesis and ABA-mediated stomatal closing and gene expression.

Restriction enzyme cleavage of ultraviolet-damaged Simian virus 40 and pBR322 DNA

International Nuclear Information System (INIS)

Cleaver, J.E.

1983-01-01

Cleavage of specific DNA sequences by the restriction enzymes EcoRI, HindIII and TaqI was prevented when the DNA was irradiated with ultraviolet light. Most of the effects were attributed to cyclobutane pyrimidine dimers in the recognition sequences; the effectiveness of irradiation was directly proportional to the number of potential dimer sites in the DNA. Combining EcoRI with dimer-specific endonuclease digestion revealed that pyrimidine dimers blocked cleavage within one base-pair on the strand opposite to the dimer but did not block cleavage three to four base-pairs away on the same strand. These are the probable limits for the range of influence of pyrimidine dimers along the DNA, at least for this enzyme. The effect of irradiation on cleavage by TaqI seemed far greater than expected for the cyclobutane dimer yield, possibly because of effects from photoproducts flanking the tetranucleotide recognition sequence and the effect of non-cyclobutane (6-4)pyrimidine photoproducts involving adjacent T and C bases. (author)

Control of extracellular cleavage of ProBDNF by high frequency neuronal activity

OpenAIRE

Nagappan, Guhan; Zaitsev, Eugene; Senatorov, Vladimir V.; Yang, Jianmin; Hempstead, Barbara L.; Lu, Bai

2009-01-01

Pro- and mature neurotrophins often elicit opposing biological effects. For example, mature brain-derived neurotrophic factor (mBDNF) is critical for long-term potentiation induced by high-frequency stimulation, whereas proBDNF facilitate long-term depression induced by low-frequency stimulation. Because mBDNF is derived from proBDNF by endoproteolytic cleavage, mechanisms regulating the cleavage of proBDNF may control the direction of BDNF regulation. Using methods that selectively detect pr...

Uncoupling of Protease trans-Cleavage and Helicase Activities in Pestivirus NS3.

Science.gov (United States)

Zheng, Fengwei; Lu, Guoliang; Li, Ling; Gong, Peng; Pan, Zishu

2017-11-01

The nonstructural protein NS3 from the Flaviviridae family is a multifunctional protein that contains an N-terminal protease and a C-terminal helicase, playing essential roles in viral polyprotein processing and genome replication. Here we report a full-length crystal structure of the classical swine fever virus (CSFV) NS3 in complex with its NS4A protease cofactor segment (PCS) at a 2.35-Å resolution. The structure reveals a previously unidentified ∼2,200-Å 2 intramolecular protease-helicase interface comprising three clusters of interactions, representing a "closed" global conformation related to the NS3-NS4A cis -cleavage event. Although this conformation is incompatible with protease trans -cleavage, it appears to be functionally important and beneficial to the helicase activity, as the mutations designed to perturb this conformation impaired both the helicase activities in vitro and virus production in vivo Our work reveals important features of protease-helicase coordination in pestivirus NS3 and provides a key basis for how different conformational states may explicitly contribute to certain functions of this natural protease-helicase fusion protein. IMPORTANCE Many RNA viruses encode helicases to aid their RNA genome replication and transcription by unwinding structured RNA. Being naturally fused to a protease participating in viral polyprotein processing, the NS3 helicases encoded by the Flaviviridae family viruses are unique. Therefore, how these two enzyme modules coordinate in a single polypeptide is of particular interest. Here we report a previously unidentified conformation of pestivirus NS3 in complex with its NS4A protease cofactor segment (PCS). This conformational state is related to the protease cis -cleavage event and is optimal for the function of helicase. This work provides an important basis to understand how different enzymatic activities of NS3 may be achieved by the coordination between the protease and helicase through different

Micro injection moulding process validation for high precision manufacture of thermoplastic elastomer micro suspension rings

DEFF Research Database (Denmark)

Calaon, M.; Tosello, G.; Elsborg Hansen, R.

Micro injection moulding (μIM) is one of the most suitable micro manufacturing processes for flexible mass-production of multi-material functional micro components. The technology was employed in this research used to produce thermoplastic elastomer (TPE) micro suspension rings identified...... main μIM process parameters (melt temperature, injection speed, packing pressure) using the Design of Experiment statistical technique. Measurements results demonstrated the importance of calibrating mould´s master geometries to ensure correct part production and effective quality conformance...... on the frequency in order to improve the signal quality and assure acoustic reproduction fidelity. Production quality of the TPE rings drastically influence the product functionality. In the present study, a procedure for μIM TPE micro rings production optimization has been established. The procedure entail using...

Functional characterization of the proteolytic activity of the tomato black ring nepovirus RNA-1-encoded polyprotein.

Science.gov (United States)

Hemmer, O; Greif, C; Dufourcq, P; Reinbolt, J; Fritsch, C

1995-01-10

Translation of tomato black ring virus (TBRV) RNA-1 in a rabbit reticulocyte lysate leads to the synthesis of a 250K polyprotein which cleaves itself into smaller proteins of 50, 60, 120, and 190K. Polypeptides synthesized from synthetic transcripts corresponding to different regions of TBRV RNA-1 are processed only when they encode the 23K protein delimited earlier by sequence homology with the cowpea mosaic virus 24K protease. The proteolytic activity of this protein is completely lost by mutating residues C170 (to I) or L188 (to H), residues which align with conserved residues of the viral serine-like proteases. The 120K protein is generated by cleavage of the dipeptide K/A localized in front of the VPg but is not further cleaved in vitro at the K/S site (at the C terminus of the VPg) or between the protease and polymerase domains. However, both the protein VPgProPol (120K) and the protein ProPol (117K) produced in vitro from synthetic transcripts can cleave in trans the RNA-2-encoded 150K polyprotein, but they cannot cleave in trans polypeptides containing a cleavage site expressed from RNA-1 transcripts in which the protease cistron is absent or modified.

Ultrarapid mutation detection by multiplex, solid-phase chemical cleavage

Energy Technology Data Exchange (ETDEWEB)

Rowley, G.; Saad, S.; Giannelli, F.; Green, P.M. [Guy`s & St. Thomas`s Hospitals, London (United Kingdom)

1995-12-10

The chemical cleavage of mismatches in heteroduplexes formed by probe and test DNA detects and locates any sequence change in long DNA segments ({approximately}1.8 kb), and its efficiency has been well tested in the analysis of both average (e.g., coagulation factor IX) and large, complex genes (e.g., coagulation factor VIII and dystrophin). In the latter application RT/PCR products allow the examination of all essential sequences of the gene in a minimum number of reactions. We use two specific chemical reactants (hydroxylamine and osmium tetroxide) and piperidine cleavage of the above procedure to develop a very fast mutation screening method. This is based on: (1) 5{prime} or internal fluorescent labeling to allow concurrent screening of three to four DNA fragments and (2) solid-phase chemistry to use a microliter format and reduce the time required for the procedure, from amplification of sequence to gel loading inclusive, to one person-working-day. We test the two variations of the method, one entailing 5{prime} labeling of probe DNA and the other uniform labeling of both probe and target DNA, by detecting 114 known hemophilia B (coagulation factor IX) mutations and by analyzing 129 new patients. Uniform labeling of both probe and target DNA prior to formation of the heteroduplexes leads to almost twofold redundancy in the ability to detect mutations. Alternatively, the latter procedure may offer very efficient though less than 100% screening for sequence changes with only hydroxylamine. The full method with two chemical reactions (hydroxylamine and osmium tetroxide) should allow one person to screen with virtually 100% accuracy more than 300 kb of sequence in three ABI 373 gels in 1 day. 26 refs., 7 figs., 1 tab.

Criterion of cleavage crack propagation and arrest in a nuclear PWR vessel steel

International Nuclear Information System (INIS)

Bousquet, Amaury

2013-01-01

The purpose of this PhD thesis is to understand physical mechanisms of cleavage crack propagation and arrest in the 16MND5 PWR vessel steel and to propose a robust predicting model based on a brittle fracture experimental campaign of finely instrumented laboratory specimens associated with numerical computations. First, experiments were carried out on thin CT25 specimens at five temperatures (-150 C, -125 C, -100 C, -7 C, -50 C). Two kinds of crack path, straight or branching path, have been observed. To characterize crack propagation and to measure crack speed, a high-speed framing camera system was used, combined with the development of an experimental protocol which allowed to observe CT surface without icing inside the thermal chamber and on the specimen. The framing camera (520 000 fps) has allowed to have a very accurate estimation of crack speed on the complete ligament of CT (∼ 25 mm). Besides, to analyse experiments and to study the impact of viscosity on the mechanical response around the crack tip, the elastic-viscoplastic behavior of the ferritic steel has been studied up to a strain rate of 104 s -1 for the tested temperatures.The extended Finite Element Method (X-FEM) was used in CAST3M FE software to model crack propagation. Numerical computations combine a local non linear dynamic approach with a RKR type fracture stress criterion to a characteristic distance. The work carried out has confirmed the form of the criterion proposed by Prabel at -125 C, and has identified the dependencies of the criterion on temperature and strain rate. From numerical analyzes in 2D and 3D, a multi-temperature fracture stress criterion, increasing function of the strain rate, was proposed. Predictive modeling were used to confirm the identified criterion on two specimen geometries (CT and compressive ring) in mode I at different temperatures. SEM observations and 3D analyzes made with optical microscope showed that the fracture mechanism was the cleavage associated

Proton storage rings

International Nuclear Information System (INIS)

Rau, R.R.

1978-04-01

A discussion is given of proton storage ring beam dynamic characteristics. Topics considered include: (1) beam energy; (2) beam luminosity; (3) limits on beam current; (4) beam site; (5) crossing angle; (6) beam--beam interaction; (7) longitudinal instability; (8) effects of scattering processes; (9) beam production; and (10) high magnetic fields. Much of the discussion is related to the design parameters of ISABELLE, a 400 x 400 GeV proton---proton intersecting storage accelerator to be built at Brookhaven National Laboratory

Accretion in Saturn's F Ring

Science.gov (United States)

Meinke, B. K.; Esposito, L. W.; Stewart, G.

2012-12-01

opaque in occultation. We suggest that Icicles may evolve into Moonlets, which are an order of magnitude less abundant in UVIS observations. Motivated by the observations and previous models, I develop a more rigorous model of the evolution of aggregates in Saturn's F ring via tidally-modified accretion. I apply the model to the F ring for bodies of constant density undergoing binary collisions. Because the locations of the UVIS-observed clump-associated features are weakly correlated to the location of Prometheus (Esposito et al. 2012) and images show material stirred up after Prometheus passage (Murray et al. 2008), we develop an additional production term describing "enhanced growth" beyond sticking of hard spheres in binary collisions. In the scenario we devise, Prometheus creates high-density regions in which larger bodies efficiently sweep up smaller bodies. Including a term for this growth mechanism in the numerical model results in the modeled size distribution evolving to a state consistent with observations. Together, the observations and model tell a story of how moonlets are made. Prometheus may be the agent responsible for moonlet growth, a complicated and rare process in the F ring. This can explain how accretion gets the upper hand in forming F ring aggregates. Growth and destruction may be cyclical on a longer time scale. This research was supported by the Cassini project.

Proximity-activated nanoparticles: in vitro performance of specific structural modification by enzymatic cleavage

Science.gov (United States)

Adam Smith, R; Sewell, Sarah L; Giorgio, Todd D

2008-01-01

The development and in vitro performance of a modular nanoscale system capable of specific structural modification by enzymatic activity is described in this work. Due to its small physical size and adaptable characteristics, this system has the potential for utilization in targeted delivery systems and biosensing. Nanoparticle probes were synthesized containing two distinct fluorescent species including a quantum dot base particle and fluorescently labeled cleavable peptide substrate. Activity of these probes was monitored by gel electrophoresis with quantitative cleavage measurements made by fluorometric analysis. The model proximity-activated nanoparticles studied here exhibit significant susceptibility to cleavage by matrix metalloprotease-7 (MMP-7) at physiologically relevant concentrations, with nearly complete cleavage of available substrate molecules after 24 hours. This response is specific to MMP-7 enzyme activity, as cleavage is completely inhibited with the addition of EDTA. Utilization of enzyme-specific modification is a sensitive approach with broad applications for targeted therapeutics and biosensing. The versatility of this nanoparticle system is highlighted in its modular design, as it has the capability to integrate characteristics for detection, biosensing, targeting, and payload delivery into a single, multifunctional nanoparticle structure. PMID:18488420

White Ring; White ring

Energy Technology Data Exchange (ETDEWEB)

Aoki, H.; Yuzawa, H. [Nikken Sekkei Ltd., Osaka (Japan)

1998-01-05

White Ring is a citizen`s gymnasium used for figure skating and short track speed skating games of 18th Winter Olympic Games in 1998. White Ring is composed of a main-arena and a sub-arena. For the main-arena with an area 41mtimes66m, an ice link can be made by disengaging the potable floor and by flowing brine in the bridged polystyrene pipes embedded in the concrete floor. Due to the fortunate groundwater in this site, well water is used for the outside air treatment energy in 63% during heating and in 35% during cooling. Ammonia is used as a cooling medium for refrigerating facility. For the heating of audience area in the large space, heat load from the outside is reduced by enhancing the heat insulation performance of the roof of arena. The audience seats are locally heated using heaters. For the White Ring, high quality environment is realized for games through various functions of the large-scale roof of the large space. Success of the big event was expected. 15 figs., 4 tabs.

Token Ring Project

Directory of Open Access Journals (Sweden)

Adela Ionescu

2007-01-01

Full Text Available Ring topology is a simple configuration used to connect processes that communicate among themselves. A number of network standards such as token ring, token bus, and FDDI are based on the ring connectivity. This article will develop an implementation of a ring of processes that communicate among themselves via pipe links. The processes are nodes in the ring. Each process reads from its standard input and writes in its standard output. N-1 process redirects the its standard output to a standard input of the process through a pipe. When the ring-structure is designed, the project can be extended to simulate networks or to implement algorithms for mutual exclusion

PROSPER: an integrated feature-based tool for predicting protease substrate cleavage sites.

Directory of Open Access Journals (Sweden)

Jiangning Song

Full Text Available The ability to catalytically cleave protein substrates after synthesis is fundamental for all forms of life. Accordingly, site-specific proteolysis is one of the most important post-translational modifications. The key to understanding the physiological role of a protease is to identify its natural substrate(s. Knowledge of the substrate specificity of a protease can dramatically improve our ability to predict its target protein substrates, but this information must be utilized in an effective manner in order to efficiently identify protein substrates by in silico approaches. To address this problem, we present PROSPER, an integrated feature-based server for in silico identification of protease substrates and their cleavage sites for twenty-four different proteases. PROSPER utilizes established specificity information for these proteases (derived from the MEROPS database with a machine learning approach to predict protease cleavage sites by using different, but complementary sequence and structure characteristics. Features used by PROSPER include local amino acid sequence profile, predicted secondary structure, solvent accessibility and predicted native disorder. Thus, for proteases with known amino acid specificity, PROSPER provides a convenient, pre-prepared tool for use in identifying protein substrates for the enzymes. Systematic prediction analysis for the twenty-four proteases thus far included in the database revealed that the features we have included in the tool strongly improve performance in terms of cleavage site prediction, as evidenced by their contribution to performance improvement in terms of identifying known cleavage sites in substrates for these enzymes. In comparison with two state-of-the-art prediction tools, PoPS and SitePrediction, PROSPER achieves greater accuracy and coverage. To our knowledge, PROSPER is the first comprehensive server capable of predicting cleavage sites of multiple proteases within a single substrate

A tree-ring perspective on the terrestrial carbon cycle

International Nuclear Information System (INIS)

Babst, F.; Alexander, M.R.; Szejner, P.; Trouet, V.; Alexander, M.R.; Moore, D.J.P.; Bouriaud, O.; Klesse, S.; Frank, D.; Roden, J.; Ciais, P.; Poulter, B.

2014-01-01

Tree-ring records can provide valuable information to advance our understanding of contemporary terrestrial carbon cycling and to reconstruct key metrics in the decades preceding monitoring data. The growing use of tree rings in carbon-cycle research is being facilitated by increasing recognition of reciprocal benefits among research communities. Yet, basic questions persist regarding what tree rings represent at the ecosystem level, how to optimally integrate them with other data streams, and what related challenges need to be overcome. It is also apparent that considerable unexplored potential exists for tree rings to refine assessments of terrestrial carbon cycling across a range of temporal and spatial domains. Here, we summarize recent advances and highlight promising paths of investigation with respect to (1) growth phenology, (2) forest productivity trends and variability, (3) CO 2 fertilization and water-use efficiency, (4) forest disturbances, and (5) comparisons between observational and computational forest productivity estimates. We encourage the integration of tree-ring data: with eddy-covariance measurements to investigate carbon allocation patterns and water-use efficiency; with remotely sensed observations to distinguish the timing of cambial growth and leaf phenology; and with forest inventories to develop continuous, annually resolved and long-term carbon budgets. In addition, we note the potential of tree-ring records and derivatives thereof to help evaluate the performance of earth system models regarding the simulated magnitude and dynamics of forest carbon uptake, and inform these models about growth responses to (non-)climatic drivers. Such efforts are expected to improve our understanding of forest carbon cycling and place current developments into a long-term perspective. (authors)

Semi-algebraic function rings and reflectors of partially ordered rings

CERN Document Server

Schwartz, Niels

1999-01-01

The book lays algebraic foundations for real geometry through a systematic investigation of partially ordered rings of semi-algebraic functions. Real spectra serve as primary geometric objects, the maps between them are determined by rings of functions associated with the spectra. The many different possible choices for these rings of functions are studied via reflections of partially ordered rings. Readers should feel comfortable using basic algebraic and categorical concepts. As motivational background some familiarity with real geometry will be helpful. The book aims at researchers and graduate students with an interest in real algebra and geometry, ordered algebraic structures, topology and rings of continuous functions.

A Stereoselective [3+1] Ring Expansion for the Synthesis of Highly Substituted Methylene Azetidines.

Science.gov (United States)

Schmid, Steven C; Guzei, Ilia A; Schomaker, Jennifer M

2017-09-25

The reaction of rhodium-bound carbenes with strained bicyclic methylene aziridines results in a formal [3+1] ring expansion to yield highly substituted methylene azetidines with excellent regio- and stereoselectivity. The reaction appears to proceed through an ylide-type mechanism, where the unique strain and structure of the methylene aziridine promotes a ring-opening/ring-closing cascade that efficiently transfers chirality from substrate to product. The resultant products can be elaborated into new azetidine scaffolds containing vicinal tertiary-quaternary and even quaternary-quaternary stereocenters. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rotating ring-ring electrode theory and experiment

NARCIS (Netherlands)

Kuiken, H.K.; Bakkers, E.P.A.M.; Ligthart, H.; Kellyb, J.J.

2000-01-01

A model is presented for the rotating ring-ring electrode. Although the electrode is defined by four characteristic lengths, it is shown that the collection efficiency depends on only two dimensionless parameters. A simple relationship between these and the corresponding parameters for the rotating

Efficient, regioselective ring-opening of activated aziridine-2-carboxylates with [¹⁸F]fluoride

DEFF Research Database (Denmark)

Schjøth-Eskesen, Christina; Hansen, Paul Robert; Kjær, Andreas

2015-01-01

Aziridines can undergo a range of ring-opening reactions with nucleophiles. The regio- and stereochemistry of the products depend on the substituents on the aziridine. Aziridine ring-opening reactions have rarely been used in radiosynthesis. Herein we report the ring opening of activated aziridine...

Natural occurrence, biological activities and synthesis of eight-, nine-, and eleven-membered ring lactones

Directory of Open Access Journals (Sweden)

Helena M. C. Ferraz

2008-01-01

Full Text Available The natural occurrence, biological activities and synthetic approaches to natural eight-, nine-, and eleven-membered lactones is reviewed. These medium ring lactones are grouped according to ring size, and their syntheses are discussed. The structures of some natural products early identified as medium-ring lactones were revised after total synthesis.

Signal peptide discrimination and cleavage site identification using SVM and NN.

Science.gov (United States)

Kazemian, H B; Yusuf, S A; White, K

2014-02-01

About 15% of all proteins in a genome contain a signal peptide (SP) sequence, at the N-terminus, that targets the protein to intracellular secretory pathways. Once the protein is targeted correctly in the cell, the SP is cleaved, releasing the mature protein. Accurate prediction of the presence of these short amino-acid SP chains is crucial for modelling the topology of membrane proteins, since SP sequences can be confused with transmembrane domains due to similar composition of hydrophobic amino acids. This paper presents a cascaded Support Vector Machine (SVM)-Neural Network (NN) classification methodology for SP discrimination and cleavage site identification. The proposed method utilises a dual phase classification approach using SVM as a primary classifier to discriminate SP sequences from Non-SP. The methodology further employs NNs to predict the most suitable cleavage site candidates. In phase one, a SVM classification utilises hydrophobic propensities as a primary feature vector extraction using symmetric sliding window amino-acid sequence analysis for discrimination of SP and Non-SP. In phase two, a NN classification uses asymmetric sliding window sequence analysis for prediction of cleavage site identification. The proposed SVM-NN method was tested using Uni-Prot non-redundant datasets of eukaryotic and prokaryotic proteins with SP and Non-SP N-termini. Computer simulation results demonstrate an overall accuracy of 0.90 for SP and Non-SP discrimination based on Matthews Correlation Coefficient (MCC) tests using SVM. For SP cleavage site prediction, the overall accuracy is 91.5% based on cross-validation tests using the novel SVM-NN model. © 2013 Published by Elsevier Ltd.

Sequence specificity of DNA cleavage by Micrococcus luteus γ endonuclease

International Nuclear Information System (INIS)

Hentosh, P.; Henner, W.D.; Reynolds, R.J.

1985-01-01

DNA fragments of defined sequence have been used to determine the sites of cleavage by γ-endonuclease activity in extracts prepared from Micrococcus luteus. End-labeled DNA restriction fragments of pBR322 DNA that had been irradiated under nitrogen in the presence of potassium iodide or t-butanol were treated with M. luteus γ endonuclease and analyzed on irradiated DNA preferentially at the positions of cytosines and thymines. DNA cleavage occurred immediately to the 3' side of pyrimidines in irradiated DNA and resulted in fragments that terminate in a 5'-phosphoryl group. These studies indicate that both altered cytosines and thymines may be important DNA lesions requiring repair after exposure to γ radiation

Topological ring currents in the "empty" ring of benzo-annelated perylenes.

Science.gov (United States)

Dickens, Timothy K; Mallion, Roger B

2011-01-27

Cyclic conjugation in benzo-annelated perylenes is examined by means of the topological π-electron ring currents calculated for each of their constituent rings, in a study that is an exact analogy of a recent investigation by Gutman et al. based on energy-effect values for the corresponding rings in each of these structures. "Classical" approaches, such as Kekulé structures, Clar "sextet" formulas, and circuits of conjugation, predict that the central ring in perylene is "empty" and thus contributes negligibly to cyclic conjugation. However, conclusions from the present calculations of topological ring currents agree remarkably with those arising from the earlier study involving energy-effect values in that, contrary to what would be predicted from the classical approaches, rings annelated in an angular fashion relative to the central ring of these perylene structures materially increase the extent of that ring's involvement in cyclic conjugation. It is suggested that such close quantitative agreement between the predictions of these two superficially very different indices (energy effect and topological ring current) might be due to the fact that, ultimately, both depend, albeit in ostensibly quite different ways, only on an adjacency matrix that contains information about the carbon-carbon connectivity of the conjugated system in question.

Inhibition of Cellular Adhesion by Immunological Targeting of Osteopontin Neoepitopes Generated through Matrix Metalloproteinase and Thrombin Cleavage.

Science.gov (United States)

Jürets, Alexander; Le Bras, Marie; Staffler, Günther; Stein, Gesine; Leitner, Lukas; Neuhofer, Angelika; Tardelli, Matteo; Turkof, Edvin; Zeyda, Maximilian; Stulnig, Thomas M

2016-01-01

Osteopontin (OPN), a secreted protein involved in inflammatory processes and cancer, induces cell adhesion, migration, and activation of inflammatory pathways in various cell types. Cells bind OPN via integrins at a canonical RGD region in the full length form as well as to a contiguous cryptic site that some have shown is unmasked upon thrombin or matrix metalloproteinase cleavage. Thus, the adhesive capacity of osteopontin is enhanced by proteolytic cleavage that may occur in inflammatory conditions such as obesity, atherosclerosis, rheumatoid arthritis, tumor growth and metastasis. Our aim was to inhibit cellular adhesion to recombinant truncated proteins that correspond to the N-terminal cleavage products of thrombin- or matrix metalloproteinase-cleaved OPN in vitro. We specifically targeted the cryptic integrin binding site with monoclonal antibodies and antisera induced by peptide immunization of mice. HEK 293 cells adhered markedly stronger to truncated OPN proteins than to full length OPN. Without affecting cell binding to the full length form, the raised monoclonal antibodies specifically impeded cellular adhesion to the OPN fragments. Moreover, we show that the peptides used for immunization were able to induce antisera, which impeded adhesion either to all OPN forms, including the full-length form, or selectively to the corresponding truncated recombinant proteins. In conclusion, we developed immunological tools to selectively target functional properties of protease-cleaved OPN forms, which could find applications in treatment and prevention of various inflammatory diseases and cancers.

DNA Cleavage Activity of Diazonium Salts: Chemical Nucleases

OpenAIRE

KIZIL, Murat

2014-01-01

4-Fenoldiazonium tetrafluoroborate and 4-benzoicaciddiazonium tetrafluoroborate was prepared and was shown to be an effective DNA cleavage agent in the presence of the 1-electron donor copper(II) chloride. Its mechanism involves the generation of the aryl radical cleaving DNA by hydrogen atom abstraction from deoxyribose sugar.

DNA and protein binding, double-strand DNA cleavage and cytotoxicity of mixed ligand copper(II) complexes of the antibacterial drug nalidixic acid.

Science.gov (United States)

Loganathan, Rangasamy; Ganeshpandian, Mani; Bhuvanesh, Nattamai S P; Palaniandavar, Mallayan; Muruganantham, Amsaveni; Ghosh, Swapan K; Riyasdeen, Anvarbatcha; Akbarsha, Mohammad Abdulkader

2017-09-01

The water soluble mixed ligand complexes [Cu(nal)(diimine)(H 2 O)](ClO 4 ) 1-4, where H(nal) is nalidixic acid and diimine is 2,2'-bipyridine (1), 1,10-phenanthroline (2), 5,6-dimethyl-1,10-phenanthroline (3), and 3,4,7,8-tetramethyl-1,10-phenanthroline (4), have been isolated. The coordination geometry around Cu(II) in 1 and that in the Density Functional Theory optimized structures of 1-4 has been assessed as square pyramidal. The trend in DNA binding constants (K b ) determined using absorption spectral titration (K b : 1, 0.79±0.1base pair. In contrast, 3 and 4 are involved in intimate hydrophobic interaction with DNA through the methyl substituents on phen ring, which is supported by viscosity and protein binding studies. DNA docking studies imply that 4 is involved preferentially in DNA major groove binding while 1-3 in minor groove binding and that all the complexes, upon removing the axially coordinated water molecule, bind in the major groove. Interestingly, 3 and 4 display prominent double-strand DNA cleavage while 1 and 2 effect only single-strand DNA cleavage in the absence of an activator. The complexes 3 and 4 show cytotoxicity higher than 1 and 2 against human breast cancer cell lines (MCF-7). The complex 4 induces apoptotic mode of cell death in cancer cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Autoactivation of mouse trypsinogens is regulated by chymotrypsin C via cleavage of the autolysis loop.

Science.gov (United States)

Németh, Balázs Csaba; Wartmann, Thomas; Halangk, Walter; Sahin-Tóth, Miklós

2013-08-16

Chymotrypsin C (CTRC) is a proteolytic regulator of trypsinogen autoactivation in humans. CTRC cleavage of the trypsinogen activation peptide stimulates autoactivation, whereas cleavage of the calcium binding loop promotes trypsinogen degradation. Trypsinogen mutations that alter these regulatory cleavages lead to increased intrapancreatic trypsinogen activation and cause hereditary pancreatitis. The aim of this study was to characterize the regulation of autoactivation of mouse trypsinogens by mouse Ctrc. We found that the mouse pancreas expresses four trypsinogen isoforms to high levels, T7, T8, T9, and T20. Only the T7 activation peptide was cleaved by mouse Ctrc, causing negligible stimulation of autoactivation. Surprisingly, mouse Ctrc poorly cleaved the calcium binding loop in all mouse trypsinogens. In contrast, mouse Ctrc readily cleaved the Phe-150-Gly-151 peptide bond in the autolysis loop of T8 and T9 and inhibited autoactivation. Mouse chymotrypsin B also cleaved the same peptide bond but was 7-fold slower. T7 was less sensitive to chymotryptic regulation, which involved slow cleavage of the Leu-149-Ser-150 peptide bond in the autolysis loop. Modeling indicated steric proximity of the autolysis loop and the activation peptide in trypsinogen, suggesting the cleaved autolysis loop may directly interfere with activation. We conclude that autoactivation of mouse trypsinogens is under the control of mouse Ctrc with some notable differences from the human situation. Thus, cleavage of the trypsinogen activation peptide or the calcium binding loop by Ctrc is unimportant. Instead, inhibition of autoactivation via cleavage of the autolysis loop is the dominant mechanism that can mitigate intrapancreatic trypsinogen activation.

Kayser-Fleischer Rings

Science.gov (United States)

... Support Contacts Lab Tracker/Copper Calculator Stories Programs & Research ... About Everything you need to know about Wilson Disease Kayser-Fleischer Rings Definition Kayser-Fleischer Ring: Clinical sign. Brownish-yellow ring visible around the corneo- ...

Carotenoid β-Ring Hydroxylase and Ketolase from Marine Bacteria—Promiscuous Enzymes for Synthesizing Functional Xanthophylls

Science.gov (United States)

Misawa, Norihiko

2011-01-01

Marine bacteria belonging to genera Paracoccus and Brevundimonas of the α-Proteobacteria class can produce C40-type dicyclic carotenoids containing two β-end groups (β rings) that are modified with keto and hydroxyl groups. These bacteria produce astaxanthin, adonixanthin, and their derivatives, which are ketolated by carotenoid β-ring 4(4′)-ketolase (4(4′)-oxygenase; CrtW) and hydroxylated by carotenoid β-ring 3(3′)-hydroxylase (CrtZ). In addition, the genus Brevundimonas possesses a gene for carotenoid β-ring 2(2′)-hydroxylase (CrtG). This review focuses on these carotenoid β-ring-modifying enzymes that are promiscuous for carotenoid substrates, and pathway engineering for the production of xanthophylls (oxygen-containing carotenoids) in Escherichia coli, using these enzyme genes. Such pathway engineering researches are performed towards efficient production not only of commercially important xanthophylls such as astaxanthin, but also of xanthophylls minor in nature (e.g., β-ring(s)-2(2′)-hydroxylated carotenoids). PMID:21673887

Carotenoid β-Ring Hydroxylase and Ketolase from Marine Bacteria—Promiscuous Enzymes for Synthesizing Functional Xanthophylls

Directory of Open Access Journals (Sweden)

Norihiko Misawa

2011-05-01

Full Text Available Marine bacteria belonging to genera Paracoccus and Brevundimonas of the α-Proteobacteria class can produce C40-type dicyclic carotenoids containing two β-end groups (β rings that are modified with keto and hydroxyl groups. These bacteria produce astaxanthin, adonixanthin, and their derivatives, which are ketolated by carotenoid β-ring 4(4′-ketolase (4(4′-oxygenase; CrtW and hydroxylated by carotenoid β-ring 3(3′-hydroxylase (CrtZ. In addition, the genus Brevundimonas possesses a gene for carotenoid β-ring 2(2′-hydroxylase (CrtG. This review focuses on these carotenoid β-ring-modifying enzymes that are promiscuous for carotenoid substrates, and pathway engineering for the production of xanthophylls (oxygen-containing carotenoids in Escherichia coli, using these enzyme genes. Such pathway engineering researches are performed towards efficient production not only of commercially important xanthophylls such as astaxanthin, but also of xanthophylls minor in nature (e.g., β-ring(s-2(2′-hydroxylated carotenoids.

Carotenoid β-ring hydroxylase and ketolase from marine bacteria-promiscuous enzymes for synthesizing functional xanthophylls.

Science.gov (United States)

Misawa, Norihiko

2011-01-01

Marine bacteria belonging to genera Paracoccus and Brevundimonas of the α-Proteobacteria class can produce C₄₀-type dicyclic carotenoids containing two β-end groups (β rings) that are modified with keto and hydroxyl groups. These bacteria produce astaxanthin, adonixanthin, and their derivatives, which are ketolated by carotenoid β-ring 4(4')-ketolase (4(4')-oxygenase; CrtW) and hydroxylated by carotenoid β-ring 3(3')-hydroxylase (CrtZ). In addition, the genus Brevundimonas possesses a gene for carotenoid β-ring 2(2')-hydroxylase (CrtG). This review focuses on these carotenoid β-ring-modifying enzymes that are promiscuous for carotenoid substrates, and pathway engineering for the production of xanthophylls (oxygen-containing carotenoids) in Escherichia coli, using these enzyme genes. Such pathway engineering researches are performed towards efficient production not only of commercially important xanthophylls such as astaxanthin, but also of xanthophylls minor in nature (e.g., β-ring(s)-2(2')-hydroxylated carotenoids).

RISC-interacting clearing 3'- 5' exoribonucleases (RICEs) degrade uridylated cleavage fragments to maintain functional RISC in Arabidopsis thaliana.

Science.gov (United States)

Zhang, Zhonghui; Hu, Fuqu; Sung, Min Woo; Shu, Chang; Castillo-González, Claudia; Koiwa, Hisashi; Tang, Guiliang; Dickman, Martin; Li, Pingwei; Zhang, Xiuren

2017-05-02

RNA-induced silencing complex (RISC) is composed of miRNAs and AGO proteins. AGOs use miRNAs as guides to slice target mRNAs to produce truncated 5' and 3' RNA fragments. The 5' cleaved RNA fragments are marked with uridylation for degradation. Here, we identified novel cofactors of Arabidopsis AGOs, named RICE1 and RICE2. RICE proteins specifically degraded single-strand (ss) RNAs in vitro; but neither miRNAs nor miRNA*s in vivo. RICE1 exhibited a DnaQ-like exonuclease fold and formed a homohexamer with the active sites located at the interfaces between RICE1 subunits. Notably, ectopic expression of catalytically-inactive RICE1 not only significantly reduced miRNA levels; but also increased 5' cleavage RISC fragments with extended uridine tails. We conclude that RICEs act to degrade uridylated 5' products of AGO cleavage to maintain functional RISC. Our study also suggests a possible link between decay of cleaved target mRNAs and miRNA stability in RISC.

Planetary Rings

Science.gov (United States)

Nicholson, P. D.

2001-11-01

A revolution in the studies in planetary rings studies occurred in the period 1977--1981, with the serendipitous discovery of the narrow, dark rings of Uranus, the first Voyager images of the tenuous jovian ring system, and the many spectacular images returned during the twin Voyager flybys of Saturn. In subsequent years, ground-based stellar occultations, HST observations, and the Voyager flybys of Uranus (1986) and Neptune (1989), as well as a handful of Galileo images, provided much additional information. Along with the completely unsuspected wealth of detail these observations revealed came an unwelcome problem: are the rings ancient or are we privileged to live at a special time in history? The answer to this still-vexing question may lie in the complex gravitational interactions recent studies have revealed between the rings and their retinues of attendant satellites. Among the four known ring systems, we see elegant examples of Lindblad and corotation resonances (first invoked in the context of galactic disks), electromagnetic resonances, spiral density waves and bending waves, narrow ringlets which exhibit internal modes due to collective instabilities, sharp-edged gaps maintained via tidal torques from embedded moonlets, and tenuous dust belts created by meteoroid impact onto parent bodies. Perhaps most puzzling is Saturn's multi-stranded, clumpy F ring, which continues to defy a simple explanation 20 years after it was first glimpsed in grainy images taken by Pioneer 11. Voyager and HST images reveal a complex, probably chaotic, dynamical interaction between unseen parent bodies within this ring and its two shepherd satellites, Pandora and Prometheus. The work described here reflects contributions by Joe Burns, Jeff Cuzzi, Luke Dones, Dick French, Peter Goldreich, Colleen McGhee, Carolyn Porco, Mark Showalter, and Bruno Sicardy, as well as those of the author. This research has been supported by NASA's Planetary Geology and Geophysics program and the

Programmable RNA recognition and cleavage by CRISPR/Cas9.

Science.gov (United States)

O'Connell, Mitchell R; Oakes, Benjamin L; Sternberg, Samuel H; East-Seletsky, Alexandra; Kaplan, Matias; Doudna, Jennifer A

2014-12-11

The CRISPR-associated protein Cas9 is an RNA-guided DNA endonuclease that uses RNA-DNA complementarity to identify target sites for sequence-specific double-stranded DNA (dsDNA) cleavage. In its native context, Cas9 acts on DNA substrates exclusively because both binding and catalysis require recognition of a short DNA sequence, known as the protospacer adjacent motif (PAM), next to and on the strand opposite the twenty-nucleotide target site in dsDNA. Cas9 has proven to be a versatile tool for genome engineering and gene regulation in a large range of prokaryotic and eukaryotic cell types, and in whole organisms, but it has been thought to be incapable of targeting RNA. Here we show that Cas9 binds with high affinity to single-stranded RNA (ssRNA) targets matching the Cas9-associated guide RNA sequence when the PAM is presented in trans as a separate DNA oligonucleotide. Furthermore, PAM-presenting oligonucleotides (PAMmers) stimulate site-specific endonucleolytic cleavage of ssRNA targets, similar to PAM-mediated stimulation of Cas9-catalysed DNA cleavage. Using specially designed PAMmers, Cas9 can be specifically directed to bind or cut RNA targets while avoiding corresponding DNA sequences, and we demonstrate that this strategy enables the isolation of a specific endogenous messenger RNA from cells. These results reveal a fundamental connection between PAM binding and substrate selection by Cas9, and highlight the utility of Cas9 for programmable transcript recognition without the need for tags.

Exploitation of the Ornithine Effect Enhances Characterization of Stapled and Cyclic Peptides

Science.gov (United States)

Crittenden, Christopher M.; Parker, W. Ryan; Jenner, Zachary B.; Bruns, Kerry A.; Akin, Lucas D.; McGee, William M.; Ciccimaro, Eugene; Brodbelt, Jennifer S.

2016-05-01

A method to facilitate the characterization of stapled or cyclic peptides is reported via an arginine-selective derivatization strategy coupled with MS/MS analysis. Arginine residues are converted to ornithine residues through a deguanidination reaction that installs a highly selectively cleavable site in peptides. Upon activation by CID or UVPD, the ornithine residue cyclizes to promote cleavage of the adjacent amide bond. This Arg-specific process offers a unique strategy for site-selective ring opening of stapled and cyclic peptides. Upon activation of each derivatized peptide, site-specific backbone cleavage at the ornithine residue results in two complementary products: the lactam ring-containing portion of the peptide and the amine-containing portion. The deguanidination process not only provides a specific marker site that initiates fragmentation of the peptide but also offers a means to unlock the staple and differentiate isobaric stapled peptides.

Enzymatic carotenoid cleavage in star fruit (Averrhoa carambola).

Science.gov (United States)

Fleischmann, Peter; Watanabe, Naoharu; Winterhalter, Peter

2003-05-01

This paper presents the first description of an enzyme fraction exhibiting carotenoid cleavage activity isolated from fruit skin of Averrhoa carambola. Partial purification of the enzyme could be achieved by acetone precipitation, ultrafiltration (300 kDa, 50 kDa), isoelectric focusing (pH 3-10) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (7.5%). In this way, an enzymatically active protein fraction was obtained, consisting of four proteins in the molecular weight range of between 12 and 90 kDa. Using beta-carotene as substrate, the enzyme activity was detected spectrophotometrically at 505 nm. The main reaction product, detected by GC analysis, was beta-ionone. This proves that the isolated enzymes are closely related to aroma metabolism and release of star fruit. The time constant of the reaction was 16.6 min, the Michaelis Constant K(m)=3.6 micromol 1(-1) and the maximum velocity V(max)=10.5 x 10(-3) micromol l(-1) s(-1) mg((Protein))(-1). The optimum temperature was 45 degrees C.

Conservation of a proteinase cleavage site between an insect retrovirus (gypsy) Env protein and a baculovirus envelope fusion protein

International Nuclear Information System (INIS)

Pearson, Margot N.; Rohrmann, George F.

2004-01-01

The predicted Env protein of insect retroviruses (errantiviruses) is related to the envelope fusion protein of a major division of the Baculoviridae. The highest degree of homology is found in a region that contains a furin cleavage site in the baculovirus proteins and an adjacent sequence that has the properties of a fusion peptide. In this investigation, the homologous region in the Env protein of the gypsy retrovirus of Drosophila melanogaster (DmegypV) was investigated. Alteration of the predicted DmegypV Env proteinase cleavage site from RIAR to AIAR significantly reduced cleavage of Env in both Spodoptera frugiperda (Sf-9) and D. melanogaster (S2) cell lines. When the predicted DmegypV Env cleavage site RIAR was substituted for the cleavage sequence RRKR in the Lymantria dispar nucleopolyhedrovirus fusion protein (LD130) sequence, cleavage of the hybrid LD130 molecules still occurred, although at a reduced level. The conserved 21-amino acid sequence just downstream of the cleavage site, which is thought to be the fusion peptide in LD130, was also characterized. When this sequence from DmegypV Env was substituted for the homologous sequence in LD130, cleavage still occurred, but no fusion was observed in either cell type. In addition, although a DmegypV-Env-green fluorescent protein construct localized to cell membranes, no cell fusion was observed

Manufacture of rings of 08Kh18N10T sheet for internal structures of WWER type reactors

International Nuclear Information System (INIS)

Fojta, A.; Nitka, B.

1984-01-01

Technology is presented of the manufacture of rings for the jacket, shaft, core catcher and shaft bottom of WWER-440 reactors produced by Vitkovice Steel Works. The rings are manufactured from sheets of austenitic steel 08Kh18N10T. The materials and technology problems are discussed of sheet production, ring welding technology and annealing following welding. The plastic properties are assessed of the welded joints and problems are outlined of ring production for WWER-1000 reactors. (B.S.)

High-level expression of an antimicrobial peptide histonin as a natural form by multimerization and furin-mediated cleavage.

Science.gov (United States)

Kim, Jung Min; Jang, Su A; Yu, Byung Jo; Sung, Bong Hyun; Cho, Ju Hyun; Kim, Sun Chang

2008-02-01

Direct expression of an antimicrobial peptide (AMP) in Escherichia coli causes several problems such as the toxicity of AMP to the host cell, its susceptibility to proteolytic degradation, and decreased antimicrobial activity due to the additional residue(s) introduced after cleavage of AMPs from fusion partners. To overcome these problems and produce a large quantity of a potent AMP histonin (RAGLQFPVGKLLKKLLKRLKR) in E. coli, an efficient expression system was developed, in which the toxicity of histonin was neutralized by a fusion partner F4 (a truncated fragment of PurF protein) and the productivity was increased by a multimeric expression of a histonin gene. The expression level of the fusion proteins reached a maximum with a 12-mer of a histonin gene. In addition, because of the RLKR residues present at the C terminus of histonin, furin cleavage of the multimeric histonin expressed produces an intact, natural histonin. The AMP activity of the histonin produced in E. coli was identical to that of a synthetic histonin. With our expression system, 167 mg of histonin was obtained from 1 l of E. coli culture. These results may lead to a cost-effective solution for the mass production of AMPs that are toxic to a host.

Cell-surface acceleration of urokinase-catalyzed receptor cleavage

DEFF Research Database (Denmark)

Høyer-Hansen, G; Ploug, M; Behrendt, N

1997-01-01

by a prior incubation of the cells with uPA inactivated by diisopropyl fluorophosphate, demonstrating a requirement for specific receptor binding of the active uPA to obtain the high-efficiency cleavage of cell-bound uPAR. Furthermore, amino-terminal sequence analysis revealed that uPAR(2+3), purified from U...

Electron--positron storage ring PETRA: plans and status

International Nuclear Information System (INIS)

Voss, G.A.

1977-01-01

Construction of the Electron-Positron Storage Ring PETRA was authorized October 20, 1975. At present most of the civil engineering work is completed and ring installation work is under way. All major components are on order and series production of bending magnets, quadrupoles, vacuum chambers and rf-resonators has started. Start-up of the machine is planned with a fourfold symmetry configuration with four active beam-beam interaction points. Five experimental facilities have been recommended for the first round of experiments scheduled to begin mid 79

Fetal hemoglobin is much less prone to DNA cleavage compared to the adult protein

Directory of Open Access Journals (Sweden)

Sandeep Chakane

2017-08-01

Full Text Available Hemoglobin (Hb is well protected inside the red blood cells (RBCs. Upon hemolysis and when free in circulation, Hb can be involved in a range of radical generating reactions and may thereby attack several different biomolecules. In this study, we have examined the potential damaging effects of cell-free Hb on plasmid DNA (pDNA. Hb induced cleavage of supercoiled pDNA (sc pDNA which was proportional to the concentration of Hb applied. Almost 70% of sc pDNA was converted to open circular or linear DNA using 10 µM of Hb in 12 h. Hb can be present in several different forms. The oxy (HbO2 and met forms are most reactive, while the carboxy-protein shows only low hydrolytic activity. Hemoglobin A (HbA could easily induce complete pDNA cleavage while fetal hemoglobin (HbF was three-fold less reactive. By inserting, a redox active cysteine residue on the surface of the alpha chain of HbF by site-directed mutagenesis, the DNA cleavage reaction was enhanced by 82%. Reactive oxygen species were not directly involved in the reaction since addition of superoxide dismutase and catalase did not prevent pDNA cleavage. The reactivity of Hb with pDNA can rather be associated with the formation of protein based radicals. Keywords: Adult hemoglobin, Fetal hemoglobin, Supercoiled plasmid DNA, DNA cleavage, Cysteine, Protein radicals

Abyssal fiction: common shares, colonial cleavages

Directory of Open Access Journals (Sweden)

Alexandre Montaury

2016-12-01

Full Text Available The paper aims to develop a reflection on the interaction between the legacies of colonialism and traditional symbolic and cultural practices in African Portuguese-speaking spaces. From a preliminary analysis of fictional texts of wide circulation in Brazil, aims to examine the cleavages, or “abyssal lines” that constitute experiences printed in the daily life of the former Portuguese colony of Cape Verde, Mozambique and Angola.---DOI: http://dx.doi.org/10.21881/abriluff.2016n17a378

Transcriptional down-regulation and rRNA cleavage in Dictyostelium discoideum mitochondria during Legionella pneumophila infection.

Directory of Open Access Journals (Sweden)

Chenyu Zhang

2009-05-01

Full Text Available Bacterial pathogens employ a variety of survival strategies when they invade eukaryotic cells. The amoeba Dictyostelium discoideum is used as a model host to study the pathogenic mechanisms that Legionella pneumophila, the causative agent of Legionnaire's disease, uses to kill eukaryotic cells. Here we show that the infection of D. discoideum by L. pneumophila results in a decrease in mitochondrial messenger RNAs, beginning more than 8 hours prior to detectable host cell death. These changes can be mimicked by hydrogen peroxide treatment, but not by other cytotoxic agents. The mitochondrial large subunit ribosomal RNA (LSU rRNA is also cleaved at three specific sites during the course of infection. Two LSU rRNA fragments appear first, followed by smaller fragments produced by additional cleavage events. The initial LSU rRNA cleavage site is predicted to be on the surface of the large subunit of the mitochondrial ribosome, while two secondary sites map to the predicted interface with the small subunit. No LSU rRNA cleavage was observed after exposure of D. discoideum to hydrogen peroxide, or other cytotoxic chemicals that kill cells in a variety of ways. Functional L. pneumophila type II and type IV secretion systems are required for the cleavage, establishing a correlation between the pathogenesis of L. pneumophila and D. discoideum LSU rRNA destruction. LSU rRNA cleavage was not observed in L. pneumophila infections of Acanthamoeba castellanii or human U937 cells, suggesting that L. pneumophila uses distinct mechanisms to interrupt metabolism in different hosts. Thus, L. pneumophila infection of D. discoideum results in dramatic decrease of mitochondrial RNAs, and in the specific cleavage of mitochondrial rRNA. The predicted location of the cleavage sites on the mitochondrial ribosome suggests that rRNA destruction is initiated by a specific sequence of events. These findings suggest that L. pneumophila specifically disrupts mitochondrial

Formation of chlorinated breakdown products during degradation of sunscreen agent, 2-ethylhexyl-4-methoxycinnamate in the presence of sodium hypochlorite.

Science.gov (United States)

Gackowska, Alicja; Przybyłek, Maciej; Studziński, Waldemar; Gaca, Jerzy

2016-01-01

In this study, a new degradation path of sunscreen active ingredient, 2-ethylhexyl-4-methoxycinnamate (EHMC) and 4-methoxycinnamic acid (MCA) in the presence of sodium hypochlorite (NaOCl), was discussed. The reaction products were detected using gas chromatography-mass spectrometry (GC-MS). Since HOCl treatment leads to more polar products than EHMC, application of polar extracting agents, dichloromethane and ethyl acetate/n-hexane mixture, gave better results in terms of chlorinated breakdown products identification than n-hexane. Reaction of EHMC with HOCl lead to the formation of C=C bridge cleavage products such as 2-ethylhexyl chloroacetate, 1-chloro-4-methoxybenzene, 1,3-dichloro-2-methoxybenzene, and 3-chloro-4-methoxybenzaldehyde. High reactivity of C=C bond attached to benzene ring is also characteristic for MCA, since it can be converted in the presence of HOCl to 2,4-dichlorophenole, 2,6-dichloro-1,4-benzoquinone, 1,3-dichloro-2-methoxybenzene, 1,2,4-trichloro-3-methoxybenzene, 2,4,6-trichlorophenole, and 3,5-dichloro-2-hydroxyacetophenone. Surprisingly, in case of EHMC/HOCl/UV, much less breakdown products were formed compared to non-UV radiation treatment. In order to describe the nature of EHMC and MCA degradation, local reactivity analysis based on the density functional theory (DFT) was performed. Fukui function values showed that electrophilic attack of HOCl to the C=C bridge in EHMC and MCA is highly favorable (even more preferable than phenyl ring chlorination). This suggests that HOCl electrophilic addition is probably the initial step of EHMC degradation.

Plutonium in tree rings from France and Japan

International Nuclear Information System (INIS)

Garrec, J.-P.; Suzuki, T.; Mahara, Y.; Santry, D.C.; Miyahara, S.; Sugahara, M.; Zheng, J.; Kudo, A.

1995-01-01

Plutonium, along with other radionuclide concentrations, was measured in evergreen tree rings from two different locations. This was used as an information source for the past two centuries. Tree rings are a product of annual layers and thus chronological information is clearly visible. Three trees were harvested in 1988-1990: a French white fir (137 years old) and a spruce tree (177 years old) from the France-Germany border near Nancy, France and a sugi (78 years old) from Nagasaki, Japan. The highest 239 + 240 Pu concentration of 30.0 mBq/kg of dry wood was obtained from the tree rings from Nagasaki, located at the centre of the local fallout of the Pu A-bomb detonated in 1945. This concentration peak was, however, observed in tree rings of 1965-67. The concentration was only 2.9 mBq/kg for the tree rings of 1944-46. The contribution of the local fallout on the surface soils from the A-bomb was 181 mBq/cm 2 at the harvested area of the tree, while the contribution of global fallout by many weapons testing was 5.9 mBq/cm 2 (or 3.3% total fallout in the region). The reason for the over 20 year time lag of 239 + 240 Pu uptake by the tree rings is unknown because many factors influence the routes of Pu into the tree rings. Also the chemical form of Pu in surface soils may have been changed by the surrounding environment. The highest concentration in the tree rings from France was 9.4 mBq/kg which is about 31% of Nagasaki 239 + 240 Pu concentration. (author)

OH-radical induced degradation of hydroxybenzoic- and hydroxycinnamic acids and formation of aromatic products-A gamma radiolysis study

Energy Technology Data Exchange (ETDEWEB)

Krimmel, Birgit; Swoboda, Friederike [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology (Austria); Solar, Sonja, E-mail: sonja.solar@univie.ac.a [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology (Austria); Reznicek, Gottfried [Department of Pharmacognosy, Althanstrasse 14, A-1090 Vienna (Austria)

2010-12-15

The OH-radical induced degradation of hydroxybenzoic acids (HBA), hydroxycinnamic acids (HCiA) and methoxylated derivatives, as well as of chlorogenic acid and rosmarinic acid was studied by gamma radiolysis in aerated aqueous solutions. Primary aromatic products resulting from an OH-radical attachment to the ring (hydroxylation), to the position occupied by the methoxyl group (replacement -OCH{sub 3} by -OH) as well as to the propenoic acid side chain of the cinnamic acids (benzaldehyde formations) were analysed by HPLC-UV and LC-ESI-MS. A comparison of the extent of these processes is given for 3,4-dihydroxybenzoic acid, vanillic acid, isovanillic acid, syringic acid, cinnamic acid, 4-hydroxycinnamic acid, caffeic acid, ferulic acid, isoferulic acid, chlorogenic acid, and rosmarinic acid. For all cinnamic acids and derivatives benzaldehydes were significant oxidation products. With the release of caffeic acid from chlorogenic acid the cleavage of a phenolic glycoside could be demonstrated. Reaction mechanisms are discussed.

An Automatic Assembling System for Sealing Rings Based on Machine Vision

Directory of Open Access Journals (Sweden)

Mingyu Gao

2017-01-01

Full Text Available In order to grab and place the sealing rings of battery lid quickly and accurately, an automatic assembling system for sealing rings based on machine vision is developed in this paper. The whole system is composed of the light sources, cameras, industrial control units, and a 4-degree-of-freedom industrial robot. Specifically, the sealing rings are recognized and located automatically with the machine vision module. Then industrial robot is controlled for grabbing the sealing rings dynamically under the joint work of multiple control units and visual feedback. Furthermore, the coordinates of the fast-moving battery lid are tracked by the machine vision module. Finally the sealing rings are placed on the sealing ports of battery lid accurately and automatically. Experimental results demonstrate that the proposed system can grab the sealing rings and place them on the sealing port of the fast-moving battery lid successfully. More importantly, the proposed system can improve the efficiency of the battery production line obviously.

Cloning and sequencing of full-length cDNAs of RNA1 and RNA2 of a Tomato black ring virus isolate from Poland.

Science.gov (United States)

Jończyk, M; Le Gall, O; Pałucha, A; Borodynko, N; Pospieszny, H

2004-04-01

Full-length cDNA clones corresponding to the RNA1 and RNA2 of the Polish isolate MJ of Tomato black ring virus (TBRV, genus Nepovirus) were obtained using a direct recombination strategy in yeast, and their complete nucleotide sequences were established. RNA1 is 7358 nucleotides and RNA2 is 4633 nucleotides in length, excluding the poly(A) tails. Both RNAs contain a single open reading frame encoding polyproteins of 254 kDa and 149 kDa for RNA1 and RNA2 respectively. Putative cleavage sites were identified, and the relationships between TBRV and related nepoviruses were studied by sequence comparison.

Cleavage strain in the Variscan fold belt, County Cork, Ireland, estimated from stretched arsenopyrite rosettes

Science.gov (United States)

Ford, M.; Ferguson, C.C.

1985-01-01

In south-west Ireland, hydrothermally formed arsenopyrite crystals in a Devonian mudstone have responded to Variscan deformation by brittle extension fracture and fragment separation. The interfragment gaps and terminal extension zones of each crystal are infilled with fibrous quartz. Stretches within the cleavage plane have been calculated by the various methods available, most of which can be modified to incorporate terminal extension zones. The Strain Reversal Method is the most accurate currently available but still gives a minimum estimate of the overall strain. The more direct Hossain method, which gives only slightly lower estimates with this data, is more practical for field use. A strain ellipse can be estimated from each crystal rosette composed of three laths (assuming the original interlimb angles were all 60??) and, because actual rather than relative stretches are estimated, this provides a lower bound to the area increase in the plane of cleavage. Based on the average of our calculated strain ellipses this area increase is at least 114% and implies an average shortening across the cleavage of at least 53%. However, several lines of evidence suggest that the cleavage deformation was more intense and more oblate than that calculated, and we argue that a 300% area increase in the cleavage plane and 75% shortening across the cleavage are more realistic estimates of the true strain. Furthermore, the along-strike elongation indicated is at least 80%, which may be regionally significant. Estimates of orogenic contraction derived from balanced section construction should therefore take into account the possibility of a substantial strike elongation, and tectonic models that can accommodate such elongations need to be developed. ?? 1985.

Computing nilpotent quotients in finitely presented Lie rings

Directory of Open Access Journals (Sweden)

Csaba Schneider

1997-12-01

Full Text Available A nilpotent quotient algorithm for finitely presented Lie rings over Z (and Q is described. The paper studies the graded and non-graded cases separately. The algorithm computes the so-called nilpotent presentation for a finitely presented, nilpotent Lie ring. A nilpotent presentation consists of generators for the abelian group and the products expressed as linear combinations for pairs formed by generators. Using that presentation the word problem is decidable in L. Provided that the Lie ring L is graded, it is possible to determine the canonical presentation for a lower central factor of L. Complexity is studied and it is shown that optimising the presentation is NP-hard. Computational details are provided with examples, timing and some structure theorems obtained from computations. Implementation in C and GAP interface are available.

Above-ground woody carbon sequestration measured from tree rings is coherent with net ecosystem productivity at five eddy-covariance sites.

Science.gov (United States)

Babst, Flurin; Bouriaud, Olivier; Papale, Dario; Gielen, Bert; Janssens, Ivan A; Nikinmaa, Eero; Ibrom, Andreas; Wu, Jian; Bernhofer, Christian; Köstner, Barbara; Grünwald, Thomas; Seufert, Günther; Ciais, Philippe; Frank, David

2014-03-01

• Attempts to combine biometric and eddy-covariance (EC) quantifications of carbon allocation to different storage pools in forests have been inconsistent and variably successful in the past. • We assessed above-ground biomass changes at five long-term EC forest stations based on tree-ring width and wood density measurements, together with multiple allometric models. Measurements were validated with site-specific biomass estimates and compared with the sum of monthly CO₂ fluxes between 1997 and 2009. • Biometric measurements and seasonal net ecosystem productivity (NEP) proved largely compatible and suggested that carbon sequestered between January and July is mainly used for volume increase, whereas that taken up between August and September supports a combination of cell wall thickening and storage. The inter-annual variability in above-ground woody carbon uptake was significantly linked with wood production at the sites, ranging between 110 and 370 g C m(-2) yr(-1) , thereby accounting for 10-25% of gross primary productivity (GPP), 15-32% of terrestrial ecosystem respiration (TER) and 25-80% of NEP. • The observed seasonal partitioning of carbon used to support different wood formation processes refines our knowledge on the dynamics and magnitude of carbon allocation in forests across the major European climatic zones. It may thus contribute, for example, to improved vegetation model parameterization and provides an enhanced framework to link tree-ring parameters with EC measurements. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Change in radiosensitivity of sea-urchin eggs during early cleavage stages

International Nuclear Information System (INIS)

Nakamura, I.

1977-01-01

When sea-urchin eggs were irradiated with 137 Cs γ-rays, their radiosensitivity, expressed by the percentage which formed pluteus larvae, fluctuated during the early cleavage cycle. Split-dose irradiations were made both in the sensitive and resistant phases. For eggs in the sensitive phase, the effect of the first exposure of 500 rad was not diminished during the interval before the second exposure. Eggs irradiated in the resistant phase were only slightly damaged. Results implied that fluctuations in radiosensitivity of sea-urchin eggs were caused mainly by different degrees of non-repairable damage in each phase of cleavage rather than by different recovery abilities. (author)

Petunia hybrida CAROTENOID CLEAVAGE DIOXYGENASE7 is involved in the production of negative and positive branching signals in petunia.

Science.gov (United States)

Drummond, Revel S M; Martínez-Sánchez, N Marcela; Janssen, Bart J; Templeton, Kerry R; Simons, Joanne L; Quinn, Brian D; Karunairetnam, Sakuntala; Snowden, Kimberley C

2009-12-01

One of the key factors that defines plant form is the regulation of when and where branches develop. The diversity of form observed in nature results, in part, from variation in the regulation of branching between species. Two CAROTENOID CLEAVAGE DIOXYGENASE (CCD) genes, CCD7 and CCD8, are required for the production of a branch-suppressing plant hormone. Here, we report that the decreased apical dominance3 (dad3) mutant of petunia (Petunia hybrida) results from the mutation of the PhCCD7 gene and has a less severe branching phenotype than mutation of PhCCD8 (dad1). An analysis of the expression of this gene in wild-type, mutant, and grafted petunia suggests that in petunia, CCD7 and CCD8 are coordinately regulated. In contrast to observations in Arabidopsis (Arabidopsis thaliana), ccd7ccd8 double mutants in petunia show an additive phenotype. An analysis using dad3 or dad1 mutant scions grafted to wild-type rootstocks showed that when these plants produce adventitious mutant roots, branching is increased above that seen in plants where the mutant roots are removed. The results presented here indicate that mutation of either CCD7 or CCD8 in petunia results in both the loss of an inhibitor of branching and an increase in a promoter of branching.

Testosterone stimulates progesterone production and STAR, P450 cholesterol side-chain cleavage and LH receptor mRNAs expression in hen (Gallus domesticus) granulosa cells.

Science.gov (United States)

Rangel, P L; Rodríguez, A; Rojas, S; Sharp, P J; Gutierrez, C G

2009-12-01

The chicken ovary is organized into a hierarchy of yellow yolky follicles that ovulate on successive days. Active or passive immunization of laying hens against testosterone blocks ovulation without affecting follicle development. Testosterone may play a role in pre-ovulatory follicle maturation by stimulating granulosa progesterone production. We assessed whether this stimulus is dose-related and depends on the maturity of the donor follicle, and if it does so by stimulating granulosa cell STAR, P450 cholesterol side-chain cleavage (P450scc), and LH receptor (LHCGR) mRNAs expression. Progesterone production by granulosa cells from F1, F3, and F4 follicles, cultured for 3 h without testosterone was greater in cells collected 11-14 h than 1-4 h after ovulation. These differences in progesterone production were less pronounced after granulosa cells had been cultured for 24 h. Culture of granulosa cells for 3 or 24 h with testosterone (1-100 ng/ml) stimulated progesterone production in cells collected from F4, F3, or F1 follicles 1-4, or 11-14 h after ovulation. Testosterone (0-4000 ng/ml) alone or in combination with LH (0-100 ng/ml) increased progesterone production by F1 granulosa cells, collected 1-4 and 11-14 h after ovulation and cultured for 3 h. Finally, testosterone (10 or 100 ng/ml) increased STAR, P450scc, and LHCGR mRNAs, when added to 3 h cultures of F1 granulosa cells. In conclusion, testosterone stimulates granulosa cell progesterone production in hen pre-ovulatory hierarchical follicles irrespective of maturational state, acting alone or additively with LH. We propose that testosterone promotes granulosa cell maturation to facilitate the pre-ovulatory release of LH.

Ring faults and ring dikes around the Orientale basin on the Moon.

Science.gov (United States)

Andrews-Hanna, Jeffrey C; Head, James W; Johnson, Brandon; Keane, James T; Kiefer, Walter S; McGovern, Patrick J; Neumann, Gregory A; Wieczorek, Mark A; Zuber, Maria T

2018-08-01

The Orientale basin is the youngest and best-preserved multiring impact basin on the Moon, having experienced only modest modification by subsequent impacts and volcanism. Orientale is often treated as the type example of a multiring basin, with three prominent rings outside of the inner depression: the Inner Rook Montes, the Outer Rook Montes, and the Cordillera. Here we use gravity data from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission to reveal the subsurface structure of Orientale and its ring system. Gradients of the gravity data reveal a continuous ring dike intruded into the Outer Rook along the plane of the fault associated with the ring scarp. The volume of this ring dike is ~18 times greater than the volume of all extrusive mare deposits associated with the basin. The gravity gradient signature of the Cordillera ring indicates an offset along the fault across a shallow density interface, interpreted to be the base of the low-density ejecta blanket. Both gravity gradients and crustal thickness models indicate that the edge of the central cavity is shifted inward relative to the equivalent Inner Rook ring at the surface. Models of the deep basin structure show inflections along the crust-mantle interface at both the Outer Rook and Cordillera rings, indicating that the basin ring faults extend from the surface to at least the base of the crust. Fault dips range from 13-22° for the Cordillera fault in the northeastern quadrant, to 90° for the Outer Rook in the northwestern quadrant. The fault dips for both outer rings are lowest in the northeast, possibly due to the effects of either the direction of projectile motion or regional gradients in pre-impact crustal thickness. Similar ring dikes and ring faults are observed around the majority of lunar basins.

Caspase Cleavages of the Lymphocyte-oriented Kinase Prevent Ezrin, Radixin, and Moesin Phosphorylation during Apoptosis*

Science.gov (United States)

Leroy, Catherine; Belkina, Natalya V.; Long, Thavy; Deruy, Emeric; Dissous, Colette; Shaw, Stephen; Tulasne, David

2016-01-01

The lymphocyte-oriented kinase (LOK), also called serine threonine kinase 10 (STK10), is synthesized mainly in lymphocytes. It is involved in lymphocyte migration and polarization and can phosphorylate ezrin, radixin, and moesin (the ERM proteins). In a T lymphocyte cell line and in purified human lymphocytes, we found LOK to be cleaved by caspases during apoptosis. The first cleavage occurs at aspartic residue 332, located between the kinase domain and the coiled-coil regulation domain. This cleavage generates an N-terminal fragment, p50 N-LOK, containing the kinase domain and a C-terminal fragment, which is further cleaved during apoptosis. Although these cleavages preserve the entire kinase domain, p50 N-LOK displays no kinase activity. In apoptotic lymphocytes, caspase cleavages of LOK are concomitant with a decrease in ERM phosphorylation. When non-apoptotic lymphocytes from mice with homozygous and heterozygous LOK knockout were compared, the latter showed a higher level of ERM phosphorylation, but when apoptosis was induced, LOK−/− and LOK+/− lymphocytes showed the same low level, confirming in vivo that LOK-induced ERM phosphorylation is prevented during lymphocyte apoptosis. Our results demonstrate that cleavage of LOK during apoptosis abolishes its kinase activity, causing a decrease in ERM phosphorylation, crucial to the role of the ERM proteins in linking the plasma membrane to actin filaments. PMID:26945071

Caspase Cleavages of the Lymphocyte-oriented Kinase Prevent Ezrin, Radixin, and Moesin Phosphorylation during Apoptosis.

Science.gov (United States)

Leroy, Catherine; Belkina, Natalya V; Long, Thavy; Deruy, Emeric; Dissous, Colette; Shaw, Stephen; Tulasne, David

2016-05-06

The lymphocyte-oriented kinase (LOK), also called serine threonine kinase 10 (STK10), is synthesized mainly in lymphocytes. It is involved in lymphocyte migration and polarization and can phosphorylate ezrin, radixin, and moesin (the ERM proteins). In a T lymphocyte cell line and in purified human lymphocytes, we found LOK to be cleaved by caspases during apoptosis. The first cleavage occurs at aspartic residue 332, located between the kinase domain and the coiled-coil regulation domain. This cleavage generates an N-terminal fragment, p50 N-LOK, containing the kinase domain and a C-terminal fragment, which is further cleaved during apoptosis. Although these cleavages preserve the entire kinase domain, p50 N-LOK displays no kinase activity. In apoptotic lymphocytes, caspase cleavages of LOK are concomitant with a decrease in ERM phosphorylation. When non-apoptotic lymphocytes from mice with homozygous and heterozygous LOK knockout were compared, the latter showed a higher level of ERM phosphorylation, but when apoptosis was induced, LOK(-/-) and LOK(+/-) lymphocytes showed the same low level, confirming in vivo that LOK-induced ERM phosphorylation is prevented during lymphocyte apoptosis. Our results demonstrate that cleavage of LOK during apoptosis abolishes its kinase activity, causing a decrease in ERM phosphorylation, crucial to the role of the ERM proteins in linking the plasma membrane to actin filaments. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Saturn's Rings Edge-on

Science.gov (United States)

1995-01-01

In one of nature's most dramatic examples of 'now-you see-them, now-you-don't', NASA's Hubble Space Telescope captured Saturn on May 22, 1995 as the planet's magnificent ring system turned edge-on. This ring-plane crossing occurs approximately every 15 years when the Earth passes through Saturn's ring plane.For comparison, the top picture was taken by Hubble on December 1, 1994 and shows the rings in a more familiar configuration for Earth observers.The bottom picture was taken shortly before the ring plane crossing. The rings do not disappear completely because the edge of the rings reflects sunlight. The dark band across the middle of Saturn is the shadow of the rings cast on the planet (the Sun is almost 3 degrees above the ring plane.) The bright stripe directly above the ring shadow is caused by sunlight reflected off the rings onto Saturn's atmosphere. Two of Saturn's icy moons are visible as tiny starlike objects in or near the ring plane. They are, from left to right, Tethys (slightly above the ring plane) and Dione.This observation will be used to determine the time of ring-plane crossing and the thickness of the main rings and to search for as yet undiscovered satellites. Knowledge of the exact time of ring-plane crossing will lead to an improved determination of the rate at which Saturn 'wobbles' about its axis (polar precession).Both pictures were taken with Hubble's Wide Field Planetary Camera 2. The top image was taken in visible light. Saturn's disk appears different in the bottom image because a narrowband filter (which only lets through light that is not absorbed by methane gas in Saturn's atmosphere) was used to reduce the bright glare of the planet. Though Saturn is approximately 900 million miles away, Hubble can see details as small as 450 miles across.The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.This image and other images and

AID-induced decrease in topoisomerase 1 induces DNA structural alteration and DNA cleavage for class switch recombination.

Science.gov (United States)

Kobayashi, Maki; Aida, Masatoshi; Nagaoka, Hitoshi; Begum, Nasim A; Kitawaki, Yoko; Nakata, Mikiyo; Stanlie, Andre; Doi, Tomomitsu; Kato, Lucia; Okazaki, Il-mi; Shinkura, Reiko; Muramatsu, Masamichi; Kinoshita, Kazuo; Honjo, Tasuku

2009-12-29

To initiate class switch recombination (CSR) activation-induced cytidine deaminase (AID) induces staggered nick cleavage in the S region, which lies 5' to each Ig constant region gene and is rich in palindromic sequences. Topoisomerase 1 (Top1) controls the supercoiling of DNA by nicking, rotating, and religating one strand of DNA. Curiously, Top1 reduction or AID overexpression causes the genomic instability. Here, we report that the inactivation of Top1 by its specific inhibitor camptothecin drastically blocked both the S region cleavage and CSR, indicating that Top1 is responsible for the S region cleavage in CSR. Surprisingly, AID expression suppressed Top1 mRNA translation and reduced its protein level. In addition, the decrease in the Top1 protein by RNA-mediated knockdown augmented the AID-dependent S region cleavage, as well as CSR. Furthermore, Top1 reduction altered DNA structure of the Smu region. Taken together, AID-induced Top1 reduction alters S region DNA structure probably to non-B form, on which Top1 can introduce nicks but cannot religate, resulting in S region cleavage.

CMS: the first barrel ring completed!

CERN Multimedia

2000-01-01

Seven years after design studies began, CERN and the German company DWE have erected the first of the five CMS yoke rings, a giant component weighing 1200 tonnes. The first ring of the CMS magnet yoke, a twelve-sided 15-metre-high colossus, has been erected in the new hall at Point 5 near Cessy. For the last few days it has stood unaided, no longer relying on the central structure required for its assembly. Its construction marks an important milestone in the CMS programme, the culmination of seven years of work at CERN and over two years of manufacturing at DWE. Awarded the contract by the Swiss Federal Institute of Technology (ETH), Zürich, the German manufacturer has produced and assembled the ring components in collaboration with a team from CERN. This feat of mechanical engineering was celebrated two weeks ago at a drink attended by the main protagonists, headed by Franz Kufner, divisional manager at DWE, Franz Leher, production engineer at DWE, Alain Hervé, CMS technical coordinator,...

Limit on the Two-Photon Production of the Glueball Candidate fJ(2220) at the Cornell Electron Storage Ring

International Nuclear Information System (INIS)

Godang, R.; Kinoshita, K.; Lai, I.C.; Pomianowski, P.; Schrenk, S.; Bonvicini, G.; Cinabro, D.; Greene, R.; Perera, L.P.; Zhou, G.J.; Barish, B.; Chadha, M.; Chan, S.; Eigen, G.; Miller, J.S.; OGrady, C.; Schmidtler, M.; Urheim, J.; Weinstein, A.J.; Wuerthwein, F.; Asner, D.M.; Bliss, D.W.; Brower, W.S.; Masek, G.; Paar, H.P.; Prell, S.; Sivertz, M.; Sharma, V.; Gronberg, J.; Hill, T.S.; Kutschke, R.; Lange, D.J.; Menary, S.; Morrison, R.J.; Nelson, H.N.; Nelson, T.K.; Qiao, C.; Richman, J.D.; Roberts, D.; Ryd, A.; Witherell, M.S.; Balest, R.; Behrens, B.H.; Cho, K.; Ford, W.T.; Park, H.; Rankin, P.; Roy, J.; Smith, J.G.; Alexander, J.P.; Bebek, C.; Berger, B.E.; Berkelman, K.; Bloom, K.; Cassel, D.G.; Cho, H.A.; Coffman, D.M.; Crowcroft, D.S.; Dickson, M.; Drell, P.S.; Ecklund, K.M.; Ehrlich, R.; Elia, R.; Foland, A.D.; Gaidarev, P.; Galik, R.S.; Gittelman, B.; Gray, S.W.; Hartill, D.L.; Heltsley, B.K.; Hopman, P.I.; Kandaswamy, J.; Katayama, N.; Kim, P.C.; Kreinick, D.L.; Lee, T.; Liu, Y.; Ludwig, G.S.; Masui, J.; Mevissen, J.; Mistry, N.B.; Ng, C.R.; Nordberg, E.; Ogg, M.; Patterson, J.R.; Peterson, D.; Riley, D.; Soffer, A.; Ward, C.; Athanas, M.; Avery, P.; Jones, C.D.; Lohner, M.; Prescott, C.; Yelton, J.; Zheng, J.; Brandenburg, G.; Briere, R.A.; Gao, Y.S.; Kim, D.Y.; Wilson, R.; Yamamoto, H.

1997-01-01

We use the CLEO detector at the Cornell e + e - storage ring, CESR, to search for the two-photon production of the glueball candidate f J (2220) in its decay to K s K s . We present a restrictive upper limit on the product of the two-photon partial width and the K s K s branching fraction, (Γ γγ B K s K s ) f J(2220) . We use this limit to calculate a lower limit on the stickiness, which is a measure of the two-gluon coupling relative to the two-photon coupling. This limit on stickiness indicates that the f J (2220) has substantial glueball content. copyright 1997 The American Physical Society

The Rotating Ring-Ring Electrode. Theory and Experiment

NARCIS (Netherlands)

Kuiken, H.K.; Bakkers, E.P.A.M.; Ligthart, H.; Kelly, J.J.

2000-01-01

A model is presented for the rotating ring-ring electrode. Although the electrode is defined by four characteristic lengths, it is shown that the collection efficiency depends on only two dimensionless parameters. A simple relationship between these and the corresponding parameters for the rotating

Resource-saving technology for manufacturing billets for piston’s rings

Directory of Open Access Journals (Sweden)

A. N. Krutilin

2010-10-01

Full Text Available Piston’s rings are one of the most critical parts of heavy-duty engines for wear-work in conditions of prolonged exposure of alternating loads and high temperatures. Currently in the world production of billets for piston’s rings is dominated by the two methods of casting: production of individual and oiling billets of gray and ductile cast iron in green-sand mold and shell mold and centrifugal casting method (intended primarily for oiling billets of ductile iron; the technology for individual production billets for piston’s rings with a diameter up to 250 mm, from 250 to 450 mm with individual and oiling ways, over 450 mm - preference of oiling billet. The best parameters of physical-mechanical and operational characteristics piston’s rings are in the case of manufacture of billets to the maximum extent approaching the configuration to the finished product. The rings made of shaped billets are characterized by uniform distribution of properties from the perimeter, provide a given diagram of pressures and full fit to the cylinder. Because of deficiencies of traditional methods of casting, continuous quality requirements for billets, the need for economy of material, fuel and energy resources, are finding new progressive technological processes of production of high-quality billets for piston’s rings. One of the most promising for piston rings billet is a method of casting consists of immersing the sand molds into the melt. It is interesting idea, expressed by A. Sutherland and subsequently patented in several countries in the way of casting method, called "immersion pouring technology" (ICT-Immersion Casting Technique [1]. Experiments, conducted in the laboratory of the Belarusian National Technical University, have identified significant shortcomings of immersion method of casting. When forms are immersing, have an intensive gassing in molten metal, and freezing of the metal on the out surface of the form. But despite some

A ring test of a wireless in vitro gas production system

DEFF Research Database (Denmark)

Cornou, Cecile; Storm, Ida Marie Lindhardt Drejer; Hindrichsen, Ida Katarina Auf der M.

2013-01-01

) or sheep (SP). Curves, corrected for blanks, were fitted using an exponential regression model with a lag time. The following variables were considered: (i) GP24 and GP48: raw values at 24 and 48 h (mL/g DM), corrected for blanks; (ii) A: asymptotic GP (mL/g DM); (iii) T1/2: time when half A is produced (h......); (iv) GPMR: maximum predicted GP rate (mL/h); (v) L: lag time (h). A mixed model including laboratories as random effect was used. A significant interaction between substrate and laboratories was found for all variables except A. The most repeatable and reproducible results were observed for A and GP48......The in vitro gas production (GP) technique has been widely used for feed evaluation. However, variability in results limits useful comparisons. Results from a ring test undertaken in four laboratories (Italy - IT, Spain - SP, Wales - WA and Denmark - DK) using the same wireless equipment (ANKOM...

Positron Options for the Linac-Ring LHeC

CERN Document Server

Zimmermann, F; Papaphilippou, Y; Schulte, D; Sievers, P; Rinolfi, L; Variola, A; Zomer, F; Braun, H H; Yakimenko, V; Bulyak, E V; Klein, M

2012-01-01

The full physics program of a future Large Hadron electron Collider (LHeC) [1] requires both pe+ and pe− collisions. For a pulsed 140-GeV or an ERL-based 60-GeV Linac-Ring LHeC this implies a challenging rate of, respectively, about 1.8 × 1015 or 4.4 × 1016 e+/s at the collision point, which is about 300 or 7000 times the rate previously obtained, at the SLAC Linear Collider (SLC). We consider providing this e+ rate through a combination of measures: (1) Reducing the required production rate from the e+ target through colliding e+ (and the LHC protons) several times before deceleration, by reusing the e+ over several acceleration/deceleration cycles, and by cooling them, e.g., with a compact tri-ring scheme or a conventional damping ring in the SPS tunnel. (2) Using an advanced target, e.g., W-granules, rotating wheel, slicedrod converter, or liquid metal jet, for converting gamma rays to e+. (3) Selecting the most powerful of several proposed gamma sources, namely Compton ERL, Compton storage ring, coher...

Wear Analysis of Top Piston Ring to Reduce Top Ring Reversal Bore Wear

Directory of Open Access Journals (Sweden)

P. Ilanthirayan

2017-12-01

Full Text Available The piston rings are the most important part in engine which controls the lubricating oil consumption and blowby of the gases. The lubricating film of oil is provided to seal of gases towards crankcase and also to give smooth friction free translatory motion between rings and liner. Of the three rings present top ring is more crucial as it does the main work of restricting gases downwards the crankcase. Boundary lubrication is present at the Top dead centre (TDC and Bottom dead centre (BDC of the liner surface. In addition to this, top ring is exposed to high temperature gases which makes the oil present near the top ring to get evaporated and decreasing its viscosity, making metal-metal contact most of the time. Due to this at TDC, excess wear happens on the liner which is termed as Top ring reversal bore wear. The wear rate depends upon many parameters such as lubrication condition, viscosity index, contact type, normal forces acting on ring, geometry of ring face, surface roughness, material property. The present work explores the wear depth for different geometries of barrel ring using Finite Element model with the help of Archard wear law and the same is validated through experimentation. The study reveals that Asymmetric barrel rings have less contact pressure which in turn reduces the wear at Top dead centre.

A novel carotenoid cleavage activity involved in the biosynthesis of Citrus fruit-specific apocarotenoid pigments

KAUST Repository

Rodrigo, María J.

2013-09-04

Citrus is the first tree crop in terms of fruit production. The colour of Citrus fruit is one of the main quality attributes, caused by the accumulation of carotenoids and their derivative C30 apocarotenoids, mainly ?-citraurin (3-hydroxy-?-apo-8?-carotenal), which provide an attractive orange-reddish tint to the peel of oranges and mandarins. Though carotenoid biosynthesis and its regulation have been extensively studied in Citrus fruits, little is known about the formation of C30 apocarotenoids. The aim of this study was to the identify carotenoid cleavage enzyme(s) [CCD(s)] involved in the peel-specific C30 apocarotenoids. In silico data mining revealed a new family of five CCD4-type genes in Citrus. One gene of this family, CCD4b1, was expressed in reproductive and vegetative tissues of different Citrus species in a pattern correlating with the accumulation of C30 apocarotenoids. Moreover, developmental processes and treatments which alter Citrus fruit peel pigmentation led to changes of ?-citraurin content and CCD4b1 transcript levels. These results point to the involvement of CCD4b1 in ?-citraurin formation and indicate that the accumulation of this compound is determined by the availability of the presumed precursors zeaxanthin and ?-cryptoxanthin. Functional analysis of CCD4b1 by in vitro assays unequivocally demonstrated the asymmetric cleavage activity at the 7?,8? double bond in zeaxanthin and ?-cryptoxanthin, confrming its role in C30 apocarotenoid biosynthesis. Thus, a novel plant carotenoid cleavage activity targeting the 7?,8? double bond of cyclic C40 carotenoids has been identified. These results suggest that the presented enzyme is responsible for the biosynthesis of C30 apocarotenoids in Citrus which are key pigments in fruit coloration. The Author 2013.

A novel carotenoid cleavage activity involved in the biosynthesis of Citrus fruit-specific apocarotenoid pigments

KAUST Repository

Rodrigo, Marí a J.; Alqué zar, Berta; Aló s, Enriqueta; Medina, Ví ctor; Carmona, Lourdes; Bruno, Mark; Al-Babili, Salim; Zacarí as, Lorenzo

2013-01-01

Citrus is the first tree crop in terms of fruit production. The colour of Citrus fruit is one of the main quality attributes, caused by the accumulation of carotenoids and their derivative C30 apocarotenoids, mainly ?-citraurin (3-hydroxy-?-apo-8?-carotenal), which provide an attractive orange-reddish tint to the peel of oranges and mandarins. Though carotenoid biosynthesis and its regulation have been extensively studied in Citrus fruits, little is known about the formation of C30 apocarotenoids. The aim of this study was to the identify carotenoid cleavage enzyme(s) [CCD(s)] involved in the peel-specific C30 apocarotenoids. In silico data mining revealed a new family of five CCD4-type genes in Citrus. One gene of this family, CCD4b1, was expressed in reproductive and vegetative tissues of different Citrus species in a pattern correlating with the accumulation of C30 apocarotenoids. Moreover, developmental processes and treatments which alter Citrus fruit peel pigmentation led to changes of ?-citraurin content and CCD4b1 transcript levels. These results point to the involvement of CCD4b1 in ?-citraurin formation and indicate that the accumulation of this compound is determined by the availability of the presumed precursors zeaxanthin and ?-cryptoxanthin. Functional analysis of CCD4b1 by in vitro assays unequivocally demonstrated the asymmetric cleavage activity at the 7?,8? double bond in zeaxanthin and ?-cryptoxanthin, confrming its role in C30 apocarotenoid biosynthesis. Thus, a novel plant carotenoid cleavage activity targeting the 7?,8? double bond of cyclic C40 carotenoids has been identified. These results suggest that the presented enzyme is responsible for the biosynthesis of C30 apocarotenoids in Citrus which are key pigments in fruit coloration. The Author 2013.

PREFACE: Special section on vortex rings Special section on vortex rings

Science.gov (United States)

Fukumoto, Yasuhide

2009-10-01

This special section of Fluid Dynamics Research includes five articles on vortex rings in both classical and quantum fluids. The leading scientists of the field describe the trends in and the state-of-the-art development of experiments, theories and numerical simulations of vortex rings. The year 2008 was the 150th anniversary of 'vortex motion' since Hermann von Helmholtz opened up this field. In 1858, Helmholtz published a paper in Crelle's Journal which put forward the concept of 'vorticity' and made the first analysis of vortex motion. Fluid mechanics before that was limited to irrotational motion. In the absence of vorticity, the motion of an incompressible homogeneous fluid is virtually equivalent to a rigid-body motion in the sense that the fluid motion is determined once the boundary configuration is specified. Helmholtz proved, among other things, that, without viscosity, a vortex line is frozen into the fluid. This Helmholtz's law immediately implies the preservation of knots and links of vortex lines and its implication is enormous. One of the major trends of fluid mechanics since the latter half of the 20th century is to clarify the topological meaning of Helmholtz's law and to exploit it to develop theoretical and numerical methods to find the solutions of the Euler equations and to develop experimental techniques to gain an insight into fluid motion. Vortex rings are prominent coherent structures in a variety of fluid motions from the microscopic scale, through human and mesoscale to astrophysical scales, and have attracted people's interest. The late professor Philip G Saffman (1981) emphasized the significance of studies on vortex rings. One particular motion exemplifies the whole range of problems of vortex motion and is also a commonly known phenomenon, namely the vortex ring or smoke ring. Vortex rings are easily produced by dropping drops of one liquid into another, or by puffing fluid out of a hole, or by exhaling smoke if one has the skill

SOCIAL CLEAVAGES IN THE AMERICAN SOCIETY AS A FACTOR OF 2016 PRESIDENTIAL CAMPAIGN

Directory of Open Access Journals (Sweden)

P. S. Kanevskiy

2017-01-01

Full Text Available Current article is dedicated to analysis of social cleavages in the American elections and the ways they influenced on presidential election in 2016. Originally developed by S. Rokkan and S.M. Lipset, social cleavages became a classic theme for contemporary political sociology. However, despite the fact that the theory has been developing primarily by Americans, it has been rarely used to analyze electoral system in the USA. Traditionally it’s been aimed at European and developing countries where electoral fragmentation is seen more clearly. But recent changes in the American society and the political system demonstrate the emergence of social cleavages that had not been inherent before. The article shows how American electoral space transformed since the 1980s and how it became more fragmented under the influence of social, economic and ideological factors. Elections in 2016 became a watershed for social cleavages that accumulated through time and aggravated even more considering internal crises in the Democratic and more so in the Republican parties. Donald Trump’s victory is an impersonation of the American party system crisis and of the mainstream politicians’ inability to find proper explanation of the changing electorate. Author shows that American society today is polarized even more than many European countries while group identification determines vectors of political change.

Electrostatic instability of some jellium model lattices of high symmetry to their plane cleavage

International Nuclear Information System (INIS)

Kholopov, Eugene V; Kalashnikova, Vita V

2007-01-01

Jellium model structures composed of regular lattices of equal point charges immersed in a neutralizing uniform background are considered. The symmetric description eliminating the effect of potentials without transverse structural modulation is extended to the events specified by alternating distances between point-charge planes. Based on modulated potentials typical of plane-wise lattice summation, the energy of interaction between two semi-infinite hemi-crystals divided by a plane is obtained for cubic and hexagonal crystals, where all the characteristic orientations of the cleavage plane are taken into account. We found that simple cubic and hexagonal lattices, as well as cubic and hexagonal diamond structures, turn out to be unstable for certain cleavage planes. The most favourable cleavage planes for the bcc, fcc and hcp structures are also emphasized

Catalytic ring opening of cyclic hydrocarbons in diesel fuels

Energy Technology Data Exchange (ETDEWEB)

Calemma, V.; Ferrari, M. [Eni S.p.A., San Donato Milanese (Italy). R and M Div.; Rabl, S.; Haas, A.; Santi, D.; Weitkamp, J. [Stuttgart Univ. (Germany). Inst. of Chemical Technology

2013-11-01

An approach for high-aromatic streams upgrading, allowing to meet future diesel quality standards, is saturation of the aromatic structures followed by the selective breaking of endocyclic C-C bonds of naphthenic structures so formed to produce alkanes with the same number of carbon atoms as the starting molecule ('selective ring opening, SRO'). Although theoretically, SRO is a promising route for upgrading low-value feeds to high-quality products, in practice, it continues to be a challenge owing to its complex chemistry. Product characteristics, do not only depend on the composition of the feed, but also on the operating conditions and the nature of the catalyst. Very recently, novel catalysts ('HIgh-PErformance Ring Opening Catalysts, HIPEROCs') were developed which allow a very selective ring opening of the model compound decalin to paraffins without degradation of the carbon number. The hydroconversion of dearomatized Light Cycle Oil (DeAr-LCO) over the abovementioned catalysts resulted in a remarkable change of the chemical structure of the feed with a strong decrease of naphthenic structures with two or more condensed rings and a concomitant increase of alkyl-substituted cyclohexanes and open-chain alkanes. The changes occurring in the chemical structures of feedstock during hydroconversion resulted in a remarkable increase of the Cetane Index of the products up to 11 units. In the present contribution, we examine the main factors affecting activity and selectivity of SRO catalysts in the light of the recent literature dealing with the subject and we report on the recent advances in hydroconversion of refinery cuts such as DeAr- LCO over HIPEROCs. (orig.)

Vortex rings

CERN Document Server

Akhmetov, D G

2009-01-01

This text on vortex rings covers their theoretical foundation, systematic investigations, and practical applications such as the extinction of fires at gushing oil wells. It pays special attention to the formation and motion of turbulent vortex rings.

Specificity and Application of the Lantibiotic Protease NisP

Directory of Open Access Journals (Sweden)

Manuel Montalbán-López

2018-02-01

Full Text Available Lantibiotics are ribosomally produced and posttranslationally modified peptides containing several lanthionine residues. They exhibit substantial antimicrobial activity against Gram-positive bacteria, including relevant pathogens. The production of the model lantibiotic nisin minimally requires the expression of the modification and export machinery. The last step during nisin maturation is the cleavage of the leader peptide. This liberates the active compound and is catalyzed by the cell wall-anchored protease NisP. Here, we report the production and purification of a soluble variant of NisP. This has enabled us to study its specificity and test its suitability for biotechnological applications. The ability of soluble NisP to cleave leaders from various substrates was tested with two sets of nisin variants. The first set was designed to investigate the influence of amino acid variations in the leader peptide or variations around the cleavage site. The second set was designed to study the influence of the lanthionine ring topology on the proteolytic efficiency. We show that the substrate promiscuity is higher than has previously been suggested. Our results demonstrate the importance of the arginine residue at the end of the leader peptide and the importance of lanthionine rings in the substrate for specific cleavage. Collectively, these data indicate that NisP is a suitable protease for the activation of diverse heterologously expressed lantibiotics, which is required to release active antimicrobial compounds.

FUZZY RINGS AND ITS PROPERTIES

Directory of Open Access Journals (Sweden)

Karyati Karyati

2017-01-01

  One of algebraic structure that involves a binary operation is a group that is defined  an un empty set (classical with an associative binary operation, it has identity elements and each element has an inverse. In the structure of the group known as the term subgroup, normal subgroup, subgroup and factor group homomorphism and its properties. Classical algebraic structure is developed to algebraic structure fuzzy by the researchers as an example semi group fuzzy and fuzzy group after fuzzy sets is introduced by L. A. Zadeh at 1965. It is inspired of writing about semi group fuzzy and group of fuzzy, a research on the algebraic structure of the ring is held with reviewing ring fuzzy, ideal ring fuzzy, homomorphism ring fuzzy and quotient ring fuzzy with its properties. The results of this study are obtained fuzzy properties of the ring, ring ideal properties fuzzy, properties of fuzzy ring homomorphism and properties of fuzzy quotient ring by utilizing a subset of a subset level  and strong level  as well as image and pre-image homomorphism fuzzy ring.   Keywords: fuzzy ring, subset level, homomorphism fuzzy ring, fuzzy quotient ring

Performance of quadrupole and sextupole magnets for the Advanced Photon Source storage ring

International Nuclear Information System (INIS)

Kim, S.H.; Doose, C.L.; Kim, K.; Thompson, K.M.; Turner, L.R.

1993-01-01

From the magnetic measurement data of several production quadrupole and sextupole magnets for the storage ring of the Advanced Photon Source, the excitation efficiencies and systematic and random multipole coefficients of the magnets are summarized. The designs of the magnets, which are constrained due to the geometry of the vacuum chamber have rotation symmetries of 180 degrees and 120 degrees. The production data meet the allowed tolerances of a few parts in 10 -4 for the storage ring

Stimulation of topoisomerase II mediated DNA cleavage at specific sequence elements by the 2-nitroimidazole Ro 15-0216

International Nuclear Information System (INIS)

Sorensen, B.S.; Jensen, P.S.; Andersen, A.H.; Christiansen, K.; Alsner, J.; Thomsen, B.; Westergaard, O.

1990-01-01

The effect of the 2-nitroimidazole Ro 15-0216 upon the interaction between purified topoisomerase II and its DNA substrate was investigated. The cleavage reaction in the presence of this DNA-nonintercalative drug took place with the hallmarks of a regular topoisomerase II mediated cleavage reaction, including covalent linkage of the enzyme to the cleaved DNA. In the presence of Ro 15-0216, topoisomerase II mediated cleavage was extensively stimulated at major cleavage sites of which only one existed in the 4363 base pair pBR322 molecule. The sites stimulated by Ro 15-0216 shared a pronounced sequence homology, indicating that a specific nucleotide sequence is crucial for the action of this drug. The effect of Ro 15-0216 thus differs from that of the clinically important topoisomerase II targeted agents such as mAMSA, VM26, and VP16, which enhance enzyme-mediated cleavage at a multiple number of sites. In contrast to the previous described drugs, Ro 15-0216 did not exert any inhibitory effect on the enzyme's catalytic activity. This observation might be ascribed to the low stability of the cleavage complexes formed in the presence of Ro 15-0216 as compared to the stability of the ones formed in the presence of traditional topoisomerase II targeted drugs

Kinetics of phycocyanobilin cleavage from C-phycocyanin by methanolysis

DEFF Research Database (Denmark)

Malwade, Chandrakant Ramkrishna; Roda Serrat, Maria Cinta; Christensen, Knud Villy

2016-01-01

Phycocyanobilin (PCB) is an important linear tetrapyrrolic molecule for food as well as pharmaceutical industry. It is obtained from blue-green algae, where it is attached covalently to phycobiliproteins (C-PC and APC) present in the light harvesting complexes. In this work, cleavage of PCB from...

The large terminase DNA packaging motor grips DNA with its ATPase domain for cleavage by the flexible nuclease domain

Science.gov (United States)

Hilbert, Brendan J.; Hayes, Janelle A.; Stone, Nicholas P.; Xu, Rui-Gang

2017-01-01

Abstract Many viruses use a powerful terminase motor to pump their genome inside an empty procapsid shell during virus maturation. The large terminase (TerL) protein contains both enzymatic activities necessary for packaging in such viruses: the adenosine triphosphatase (ATPase) that powers DNA translocation and an endonuclease that cleaves the concatemeric genome at both initiation and completion of genome packaging. However, how TerL binds DNA during translocation and cleavage remains mysterious. Here we investigate DNA binding and cleavage using TerL from the thermophilic phage P74-26. We report the structure of the P74-26 TerL nuclease domain, which allows us to model DNA binding in the nuclease active site. We screened a large panel of TerL variants for defects in binding and DNA cleavage, revealing that the ATPase domain is the primary site for DNA binding, and is required for nuclease activity. The nuclease domain is dispensable for DNA binding but residues lining the active site guide DNA for cleavage. Kinetic analysis of DNA cleavage suggests flexible tethering of the nuclease domains during DNA cleavage. We propose that interactions with the procapsid during DNA translocation conformationally restrict the nuclease domain, inhibiting cleavage; TerL release from the capsid upon completion of packaging unlocks the nuclease domains to cleave DNA. PMID:28082398

Polarization Insensitivity in Double-Split Ring and Triple-Split Ring Terahertz Resonators

International Nuclear Information System (INIS)

Wu Qian-Nan; Lan Feng; Tang Xiao-Pin; Yang Zi-Qiang

2015-01-01

A modified double-split ring resonator and a modified triple-split ring resonator, which offer polarization-insensitive performance, are investigated, designed and fabricated. By displacing the two gaps of the conventional double-split ring resonator away from the center, the second resonant frequency for the 0° polarized wave and the resonant frequency for the 90° polarized wave become increasingly close to each other until they are finally identical. Theoretical and experimental results show that the modified double-split ring resonator and the modified triple-split ring resonator are insensitive to different polarized waves and show strong resonant frequency dips near 433 and 444 GHz, respectively. The results of this work suggest new opportunities for the investigation and design of polarization-dependent terahertz devices based on split ring resonators. (paper)

Some uses of REPMM's in storage rings and colliders

International Nuclear Information System (INIS)

Spencer, J.E.

1985-04-01

Improvements for existing rings and techniques for building new rings composed entirely of passive, Rare Earth Permanent Magnet Multipoles (REPMM's) are considered using circular dipoles, quadrupoles and sextupoles. Over the past few years we have made such magnets using a single size SmCo 5 block with up to five easy-axis orientations. The final production scheme is modular in that magnets are built-up from quantized layers. All multipole layers are made in exactly the same way using algorithms differing only by the desired multipole symmetry. The method is simple, efficient and inexpensive and allows a ''do-it-yourself'' approach to constructing new magnetic elements. For rings these might include focusing optical klystrons, rotatable multipoles for diagnostics, correction or extraction, or possibly combined function systems for the unit cells. A high quality, low-beta, PMQ insertion which can change beta, tune and energy is described as well as the PMS's for the SD and SF elements of the North SLC damping ring. Because these sextupoles will be the first optical use of PM's in storage rings they are discussed in detail together with the advantages, problems and requirements of such applications. 8 refs., 4 figs

The Conserved ATM Kinase RAG2-S365 Phosphorylation Site Limits Cleavage Events in Individual Cells Independent of Any Repair Defect

Directory of Open Access Journals (Sweden)

Susannah L. Hewitt

2017-10-01

Full Text Available Many DNA lesions associated with lymphoid malignancies are linked to off-target cleavage by the RAG1/2 recombinase. However, off-target cleavage has mostly been analyzed in the context of DNA repair defects, confounding any mechanistic understanding of cleavage deregulation. We identified a conserved SQ phosphorylation site on RAG2 365 to 366 that is involved in feedback control of RAG cleavage. Mutation of serine 365 to a non-phosphorylatable alanine permits bi-allelic and bi-locus RAG-mediated breaks in the same cell, leading to reciprocal translocations. This phenomenon is analogous to the phenotype we described for ATM kinase inactivation. Here, we establish deregulated cleavage itself as a driver of chromosomal instability without the associated repair defect. Intriguingly, a RAG2-S365E phosphomimetic rescues the deregulated cleavage of ATM inactivation, reducing the incidence of reciprocal translocations. These data support a model in which feedback control of cleavage and maintenance of genome stability involves ATM-mediated phosphorylation of RAG2.

Beta-scission of alkoxyl radicals on peptides and proteins can give rise to backbone cleavage and loss of side-chains

International Nuclear Information System (INIS)

Headlam, H.A.; Davies, M.J.; Mortimer, A.; Easton, C.J.

2000-01-01

reaction, and loss of the side-chain as formaldehyde. The latter material has been quantified by product analysis. Experiments with other hydroperoxides and nitrate esters suggest that this type of reaction is a common process with many C-3 alkoxyl radicals, with the driving force for sidechain loss being the stability of the resultant α-carbon radicals; these species give rise to subsequent backbone cleavage. This pathway provides a novel mechanism by which initial reaction at side-chain sites can give rise to both backbone cleavage, and loss of side-chain groups on peptides and proteins. These reactions are also chain propagation steps as they result in damage to one amino acid and the release of a second, potentially damaging species. The significance and quantification of this pathway, compared to other routes that lead to backbone cleavage, are currently being explored

Developing a capillary electrophoresis based method for dynamically monitoring enzyme cleavage activity using quantum dots-peptide assembly.

Science.gov (United States)

Wang, Jianhao; Fan, Jie; Liu, Li; Ding, Shumin; Liu, Xiaoqian; Wang, Jianpeng; Gao, Liqian; Chattopadhaya, Souvik; Miao, Peng; Xia, Jiang; Qiu, Lin; Jiang, Pengju

2017-10-01

Herein, a novel assay has been developed for monitoring PreScission protease (His-PSP) mediated enzyme cleavage of ATTO 590 labeled peptide substrate (ATTO-LEV). This novel method is based on combining the use of capillary electrophoresis and fluorescence detection (CE-FL) to dynamically monitor the enzyme cleavage activity. A multivalent peptide substrate was first constructed by immobilizing His-tagged ATTO 590 labeled peptide substrate (ATTO-LEVH6) onto the surface of CdSe/ZnS quantum dots (QDs). Once successfully immobilized, the novel multivalent peptide substrate resulted in the Förster resonance energy transfer (FRET) from QDs to ATTO 590. The ATTO-LEVH6-QD assembly was then incubated with His-PSP to study the proteolytic cleavage of surface bound ATTO-LEVH6 by CE-FL. Our data suggests that PreScission-mediated proteolytic cleavage is enzyme concentration- and incubation time-dependent. By combining capillary electrophoresis, QDs and FRET, our study herein not only provides a new method for the detection and dynamically monitoring of PSP enzyme cleavage activity, but also can be extended to the detection of many other enzymes and proteases. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

RINGED ACCRETION DISKS: EQUILIBRIUM CONFIGURATIONS

Energy Technology Data Exchange (ETDEWEB)

Pugliese, D.; Stuchlík, Z., E-mail: d.pugliese.physics@gmail.com, E-mail: zdenek.stuchlik@physics.cz [Institute of Physics and Research Centre of Theoretical Physics and Astrophysics, Faculty of Philosophy and Science, Silesian University in Opava, Bezručovo náměstí 13, CZ-74601 Opava (Czech Republic)

2015-12-15

We investigate a model of a ringed accretion disk, made up by several rings rotating around a supermassive Kerr black hole attractor. Each toroid of the ringed disk is governed by the general relativity hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. Properties of the tori can then be determined by an appropriately defined effective potential reflecting the background Kerr geometry and the centrifugal effects. The ringed disks could be created in various regimes during the evolution of matter configurations around supermassive black holes. Therefore, both corotating and counterrotating rings have to be considered as being a constituent of the ringed disk. We provide constraints on the model parameters for the existence and stability of various ringed configurations and discuss occurrence of accretion onto the Kerr black hole and possible launching of jets from the ringed disk. We demonstrate that various ringed disks can be characterized by a maximum number of rings. We present also a perturbation analysis based on evolution of the oscillating components of the ringed disk. The dynamics of the unstable phases of the ringed disk evolution seems to be promising in relation to high-energy phenomena demonstrated in active galactic nuclei.

Stirling engine piston ring

Science.gov (United States)

Howarth, Roy B.

1983-01-01

A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

Physics of quantum rings

International Nuclear Information System (INIS)

Fomin, Vladimir M.

2014-01-01

Presents the new class of materials of quantum rings. Provides an elemental basis for low-cost high-performance devices promising for electronics, optoelectronics, spintronics and quantum information processing. Explains the physical properties of quantum rings to cover a gap in scientific literature. Presents the application of most advanced nanoengineering and nanocharacterization techniques. This book deals with a new class of materials, quantum rings. Innovative recent advances in experimental and theoretical physics of quantum rings are based on the most advanced state-of-the-art fabrication and characterization techniques as well as theoretical methods. The experimental efforts allow to obtain a new class of semiconductor quantum rings formed by capping self-organized quantum dots grown by molecular beam epitaxy. Novel optical and magnetic properties of quantum rings are associated with non-trivial topologies at the nanoscale. An adequate characterization of quantum rings is possible on the basis of modern characterization methods of nanostructures, such as Scanning Tunneling Microscopy. A high level of complexity is demonstrated to be needed for a dedicated theoretical model to adequately represent the specific features of quantum rings. The findings presented in this book contribute to develop low-cost high-performance electronic, spintronic, optoelectronic and information processing devices based on quantum rings.

Metabolic Engineering to Develop a Pathway for the Selective Cleavage of Carbon-Nitrogen Bonds

Energy Technology Data Exchange (ETDEWEB)

John J. Kilbane II

2005-10-01

The objective of the project is to develop a biochemical pathway for the selective cleavage of C-N bonds in molecules found in petroleum. Specifically a novel biochemical pathway will be developed for the selective cleavage of C-N bonds in carbazole. The cleavage of the first C-N bond in carbazole is accomplished by the enzyme carbazole dioxygenase, that catalyzes the conversion of carbazole to 2-aminobiphenyl-2,3-diol. The genes encoding carbazole dioxygenase were cloned from Sphingomonas sp. GTIN11 and from Pseudomonas resinovorans CA10. The selective cleavage of the second C-N bond has been challenging, and efforts to overcome that challenge have been the focus of recent research in this project. Enrichment culture experiments succeeded in isolating bacterial cultures that can metabolize 2-aminobiphenyl, but no enzyme capable of selectively cleaving the C-N bond in 2-aminobiphenyl has been identified. Aniline is very similar to the structure of 2-aminobiphenyl and aniline dioxygenase catalyzes the conversion of aniline to catechol and ammonia. For the remainder of the project the emphasis of research will be to simultaneously express the genes for carbazole dioxygenase and for aniline dioxygenase in the same bacterial host and then to select for derivative cultures capable of using carbazole as the sole source of nitrogen.

How does the blue-ringed octopus (Hapalochlaena lunulata) flash its blue rings?

Science.gov (United States)

Mäthger, Lydia M; Bell, George R R; Kuzirian, Alan M; Allen, Justine J; Hanlon, Roger T

2012-11-01

The blue-ringed octopus (Hapalochlaena lunulata), one of the world's most venomous animals, has long captivated and endangered a large audience: children playing at the beach, divers turning over rocks, and biologists researching neurotoxins. These small animals spend much of their time in hiding, showing effective camouflage patterns. When disturbed, the octopus will flash around 60 iridescent blue rings and, when strongly harassed, bite and deliver a neurotoxin that can kill a human. Here, we describe the flashing mechanism and optical properties of these rings. The rings contain physiologically inert multilayer reflectors, arranged to reflect blue-green light in a broad viewing direction. Dark pigmented chromatophores are found beneath and around each ring to enhance contrast. No chromatophores are above the ring; this is unusual for cephalopods, which typically use chromatophores to cover or spectrally modify iridescence. The fast flashes are achieved using muscles under direct neural control. The ring is hidden by contraction of muscles above the iridophores; relaxation of these muscles and contraction of muscles outside the ring expose the iridescence. This mechanism of producing iridescent signals has not previously been reported in cephalopods and we suggest that it is an exceptionally effective way to create a fast and conspicuous warning display.

α-Skew π-McCoy Rings

Directory of Open Access Journals (Sweden)

Areej M. Abduldaim

2013-01-01

Full Text Available As a generalization of α-skew McCoy rings, we introduce the concept of α-skew π-McCoy rings, and we study the relationships with another two new generalizations, α-skew π1-McCoy rings and α-skew π2-McCoy rings, observing the relations with α-skew McCoy rings, π-McCoy rings, α-skew Armendariz rings, π-regular rings, and other kinds of rings. Also, we investigate conditions such that α-skew π1-McCoy rings imply α-skew π-McCoy rings and α-skew π2-McCoy rings. We show that in the case where R is a nonreduced ring, if R is 2-primal, then R is an α-skew π-McCoy ring. And, let R be a weak (α,δ-compatible ring; if R is an α-skew π1-McCoy ring, then R is α-skew π2-McCoy.

Ring-enhancing spinal cord lesions in neuromyelitis optica spectrum disorders.

Science.gov (United States)

Zalewski, Nicholas L; Morris, Padraig P; Weinshenker, Brian G; Lucchinetti, Claudia F; Guo, Yong; Pittock, Sean J; Krecke, Karl N; Kaufmann, Timothy J; Wingerchuk, Dean M; Kumar, Neeraj; Flanagan, Eoin P

2017-03-01

We assessed the frequency and characteristics of ring-enhancing spinal cord lesions in neuromyelitis optica spectrum disorder (NMOSD) myelitis and myelitis of other cause. We reviewed spinal cord MRIs for ring-enhancing lesions from 284 aquaporin-4 (AQP4)-IgG seropositive patients at Mayo Clinic from 1996 to 2014. Inclusion criteria were as follows: (1) AQP4-IgG seropositivity, (2) myelitis attack and (3) MRI spinal cord demonstrating ring-enhancement. We identified two groups of control patients with: (1) longitudinally extensive myelopathy of other cause (n=66) and (2) myelitis in the context of a concurrent or subsequent diagnosis of multiple sclerosis (MS) from a population-based cohort (n=30). Ring-enhancement was detected in 50 of 156 (32%) myelitis episodes in 41 patients (83% single; 17% multiple attacks). Ring-enhancement was noted on sagittal and axial images in 36 of 43 (84%) ring enhancing myelitis episodes and extended a median of two vertebral segments (range, 1-12); in 21 of 48 (44%) ring enhancing myelitis episodes, the ring extended greater than or equal to three vertebrae. Ring-enhancement was accompanied by longitudinally extensive (greater than or equal to three vertebral segments) T2-hyperintensity in 44 of 50 (88%) ring enhancing myelitis episodes. One case of a spinal cord biopsy during ring-enhancing myelitis revealed tissue vacuolation and loss of AQP4 immunoreactivity with preserved axons. The clinical characteristics of ring-enhancing myelitis episodes did not differ from non-ring-enhancing episodes. Ring-enhancing spinal cord lesions were more common in NMOSD than other causes of longitudinally extensive myelopathy (50/156 (32%) vs 0/66 (0%); p≤0.001) but did not differ between NMOSD and MS (50/156 (32%) vs 6/30 (20%); p=0.20). Spinal cord ring-enhancement accompanies one-third of NMOSD myelitis episodes and distinguishes NMOSD from other causes of longitudinally extensive myelopathies but not from MS. Published by the BMJ Publishing

Ring Expansion and Rearrangements of Rhodium(II) Azavinyl Carbenes

Science.gov (United States)

Selander, Nicklas; Worrell, Brady T.

2013-01-01

An efficient, regioselective and convergent method for the ring expansion and rearrangement of 1-sulfonyl-1,2,3-triazoles under rhodium(II)-catalyzed conditions is described. These denitrogenative reactions form substituted enaminone and olefin-based products, which in the former case can be further functionalized to unique products rendering the sulfonyl triazole traceless. PMID:23161725

The Oxygenase CAO-1 of Neurospora crassa Is a Resveratrol Cleavage Enzyme

KAUST Repository

Diaz-Sanchez, V.; F. Estrada, A.; Limon, M. C.; Al-Babili, Salim; Avalos, J.

2013-01-01

The genome of the ascomycete Neurospora crassa encodes CAO-1 and CAO-2, two members of the carotenoid cleavage oxygenase family that target double bonds in different substrates. Previous studies demonstrated the role of CAO-2 in cleaving the C40 carotene torulene, a key step in the synthesis of the C35 apocarotenoid pigment neurosporaxanthin. In this work, we investigated the activity of CAO-1, assuming that it may provide retinal, the chromophore of the NOP-1 rhodopsin, by cleaving β-carotene. For this purpose, we tested CAO-1 activity with carotenoid substrates that were, however, not converted. In contrast and consistent with its sequence similarity to family members that act on stilbenes, CAO-1 cleaved the interphenyl Cα-Cβ double bond of resveratrol and its derivative piceatannol. CAO-1 did not convert five other similar stilbenes, indicating a requirement for a minimal number of unmodified hydroxyl groups in the stilbene background. Confirming its biological function in converting stilbenes, adding resveratrol led to a pronounced increase in cao-1 mRNA levels, while light, a key regulator of carotenoid metabolism, did not alter them. Targeted Δcao-1 mutants were not impaired by the presence of resveratrol, a phytoalexin active against different fungi, which did not significantly affect the growth and development of wild-type Neurospora. However, under partial sorbose toxicity, the Δcao-1 colonies exhibited faster radial growth than control strains in the presence of resveratrol, suggesting a moderate toxic effect of resveratrol cleavage products.

The Oxygenase CAO-1 of Neurospora crassa Is a Resveratrol Cleavage Enzyme

KAUST Repository

Diaz-Sanchez, V.

2013-07-26

The genome of the ascomycete Neurospora crassa encodes CAO-1 and CAO-2, two members of the carotenoid cleavage oxygenase family that target double bonds in different substrates. Previous studies demonstrated the role of CAO-2 in cleaving the C40 carotene torulene, a key step in the synthesis of the C35 apocarotenoid pigment neurosporaxanthin. In this work, we investigated the activity of CAO-1, assuming that it may provide retinal, the chromophore of the NOP-1 rhodopsin, by cleaving β-carotene. For this purpose, we tested CAO-1 activity with carotenoid substrates that were, however, not converted. In contrast and consistent with its sequence similarity to family members that act on stilbenes, CAO-1 cleaved the interphenyl Cα-Cβ double bond of resveratrol and its derivative piceatannol. CAO-1 did not convert five other similar stilbenes, indicating a requirement for a minimal number of unmodified hydroxyl groups in the stilbene background. Confirming its biological function in converting stilbenes, adding resveratrol led to a pronounced increase in cao-1 mRNA levels, while light, a key regulator of carotenoid metabolism, did not alter them. Targeted Δcao-1 mutants were not impaired by the presence of resveratrol, a phytoalexin active against different fungi, which did not significantly affect the growth and development of wild-type Neurospora. However, under partial sorbose toxicity, the Δcao-1 colonies exhibited faster radial growth than control strains in the presence of resveratrol, suggesting a moderate toxic effect of resveratrol cleavage products.

Mechanisms of catalytic cleavage of benzyl phenyl ether in aqueous and apolar phases

Energy Technology Data Exchange (ETDEWEB)

He, Jiayue; Lu, Lu; Zhao, Chen; Mei, Donghai; Lercher, Johannes A.

2014-03-01

Catalytic pathways for the cleavage of ether bonds in benzyl phenyl ether (BPE) in liquid phase using Ni- and zeolite-based catalysts are explored. In the absence of catalysts, the C-O bond is selectively cleaved in water by hydrolysis, forming phenol and benzyl alcohol as intermediates, followed by alkylation. The hydronium ions catalyzing the reactions are provided by the dissociation of water at 523 K. Upon addition of HZSM-5, rates of hydrolysis and alkylation are markedly increased in relation to proton concentrations. In the presence of Ni/SiO₂, the selective hydrogenolysis dominates for cleaving the C_aliphatic-O bond. Catalyzed by the dual-functional Ni/HZSM-5, hydrogenolysis occurs as the major route rather than hydrolysis (minor route). In apolar undecane, the non-catalytic thermal pyrolysis route dominates. Hydrogenolysis of BPE appears to be the major reaction pathway in undecane in the presence of Ni/SiO₂ or Ni/HZSM-5, almost completely suppressing radical reactions. Density functional theory (DFT) calculations strongly support the proposed C-O bond cleavage mechanisms on BPE in aqueous and apolar phases. These calculations show that BPE is initially protonated and subsequently hydrolyzed in the aqueous phase. Finally, DFT calculations suggest that the radical reactions in non-polar solvents lead to primary benzyl and phenoxy radicals in undecane, which leads to heavier condensation products as long as metals are absent for providing dissociated hydrogen.

VUV optical ring resonator for Duke storage ring free electron laser

Energy Technology Data Exchange (ETDEWEB)

Park, S.H.; Litvinenko, V.N.; Madey, J.M.J. [Duke Univ., Durham, NC (United States)] [and others

1995-12-31

The conceptual design of the multifaceted-mirror ring resonator for Duke storage ring VUV FEL is presented. The expected performance of the OK-4 FEL with ring resonator is described. We discuss in this paper our plans to study reflectivity of VUV mirrors and their resistivity to soft X-ray spontaneous radiation from OK-4 undulator.

Status of the PEP-II B-factory high energy ring

International Nuclear Information System (INIS)

Wienands, U.; Reuter, E.; Bellomo, P.; Daly, E.; Fisher, A.; Gracia, J.; Kulikov, A.; Kurita, N.; Pietryka, M.; Seeman, J.T.; Taylor; Belser, C.; Bertolini, L.; Mugge, M.; Swan, J.

1996-01-01

The 9 GeV High Energy Ring (HER) of the PEP-II B Factory is an electron storage ring under construction at SLAC. Significant progress has been made in the last year on all systems. As of mid 1996, all 192 dipoles have been installed, with installation of the quadrupoles underway. The vacuum system, for design currents up to 3 A average, is in production using a recently commissioned e-beam welder. Beam instrumentation systems are being fabricated. The interaction region will bring the HER beam into collision with the 3 GeV beam of the Low Energy Ring; design of this section of the HER is in an advanced stage. 8 refs., 3 figs., 1 tab

Hydrogen production through microheterogeneous photocatalysis of hydrogen sulfide cleavage. The thiosulfate cycle

Energy Technology Data Exchange (ETDEWEB)

Borgarello, E; Serpone, N; Graetzel, M; Pelizzetti, E

1985-01-01

Cleavage of hydrogen sulfide into hydrogen and sulfur occurs in alkaline aqueous CdS dispersions under visible light illumination. Small quantities of a noble metal catalyst (RuO/sub 2/) loaded onto 'naked' CdS particles markedly improve the yield of hydrogen formation. The effect of RuO/sub 2/ is ascribed to catalysis of electron transfer to proton. Simultaneous and efficient photogeneration of hydrogen and thiosulfate occurs in CdS dispersions containing both sulfite and bisulfide (or sulfide) ions. Electron transfer from the conduction band of CdS to that of TiO/sub 2/ particles occurs in alkaline suspensions containing these HS/sup -/ ions and has been exploited to improve the performance of a system achieving decomposition of H/sub 2/S by visible light. Equally important is a recent finding that the performance of a system containing 'naked' CdS in combination with RuO/sub 2/-loaded TiO/sub 2/ particles is far better than that of CdS/RuO/sub 2/ alone. Additionally, conduction band electrons produced by bandgap excitation of TiO/sub 2/ particles efficiently reduce thiosulfate to sulfide and sulfite. The valence band process in alklaine TiO/sub 2/ dispersions is thought to involve oxidation of S/sub 2/O/sub 3//sup 2 -/ to tetrathionate, S/sub 4/O/sub 6//sup 2 -/, which quantitatively dismutates into sulfite and thiosulfate. The photodriven disproportionation of thiosulfate into sulfide and sulfate is of great interest in systems that photochemically cleave hydrogen sulfide into hydrogen and sulfur. (author).

Comparison of the cleavage of pyrimidine dimers by the bacteriophage T4 and Micrococcus luteus uv-specific endonucleases

International Nuclear Information System (INIS)

Gordon, L.K.; Haseltine, W.A.

1980-01-01

A comparison was made of the activity of the uv-specific endonucleases of bacteriophage T4 (T4 endonuclease V) and of Micrococcus luteus on ultraviolet light-irradiated DNA substrates of defined sequence. The two enzyms cleave DNA at the site of pyrimidine dimers with the same frequency. The products of the cleavage reaction are the same. The pyrimidine dimer DNA-glycosylase activity of both enzymes is more active on double-stranded DNA than it is on single-stranded DNA

Thin layer activation (TLA) experiment of piston ring F.J product by using nuclear facility proton beam 12.5 MeV

International Nuclear Information System (INIS)

Sudarmono; Silakhuddin

2002-01-01

The experiment of thin layer activation of piston ring F.J product, was done. The purpose of this experiment are to measure material wearing level by using concentration method. The experiment was carried out by activated piston ring proton beam with energy 12,5 MeV and beam current 1 μA for 30 minutes then was continued by wearing process. The measurement of the wear result activity was carried out by pouring the total of volume of lubricant oil for radioactivity measurement. Measurement of the activity level used the gamma spectroscopy. The minimum wearing duration that can detects a wear was 5 hours. The activity count was 1.230 pulse per 30 seconds which is in accordance with a wear in order of 8 mg of Fe material on 1 liter oil lubricant, this result is same with the result of T. Delvigne namely is less than 10 mgr

Interaction Region Design for a Ring-Ring LHeC

CERN Document Server

Thompson, L N S; Bernard, N R; Fitterer, M; Holzer, B; Klein, M; Kostka, P

2011-01-01

tively low energy and moderately high intensity provides high luminosity TeV-scale e-p collisions at one of the LHC interaction points, running simultaneously with existing experiments. Two designs are studied; an electron ring situated in the LHC tunnel, and an electron linac. The focus of this paper is on the ring design. Designing an e-p machine presents interesting accelerator physics and design challenges, particularly when considering the interaction region. These include coupled optics, beam separation and unconventional mini-beta focusing schemes. Designs are constrained by an array of interdependent factors, including beam-beam interaction, detector dimensions and acceptance, luminosity and synchrotron radiation. Methods of addressing these complex issues are discussed. The current designs for the LHeC Ring-Ring interaction region and long straight section are presented and discussed, in the context of the project goals and design challenges encountered. Future developments and work are also discusse...

Degradation of sulfamethoxazole by UV, UV/H2O2 and UV/persulfate (PDS): Formation of oxidation products and effect of bicarbonate.

Science.gov (United States)

Yang, Yi; Lu, Xinglin; Jiang, Jin; Ma, Jun; Liu, Guanqi; Cao, Ying; Liu, Weili; Li, Juan; Pang, Suyan; Kong, Xiujuan; Luo, Congwei

2017-07-01

The frequent detection of sulfamethoxazole (SMX) in wastewater and surface waters gives rise of concerns about their ecotoxicological effects and potential risks to induce antibacterial resistant genes. UV/hydrogen peroxide (UV/H 2 O 2 ) and UV/persulfate (UV/PDS) advanced oxidation processes have been demonstrated to be effective for the elimination of SMX, but there is still a need for a deeper understanding of product formations. In this study, we identified and compared the transformation products of SMX in UV, UV/H 2 O 2 and UV/PDS processes. Because of the electrophilic nature of SO 4 - , the second-order rate constant for the reaction of sulfate radical (SO 4 - ) with the anionic form of SMX was higher than that with the neutral form, while hydroxyl radical (OH) exhibited comparable reactivity to both forms. The direct photolysis of SMX predominately occurred through cleavage of the NS bond, rearrangement of the isoxazole ring, and hydroxylation mechanisms. Hydroxylation was the dominant pathway for the reaction of OH with SMX. SO 4 - favored attack on NH 2 group of SMX to generate a nitro derivative and dimeric products. The presence of bicarbonate in UV/H 2 O 2 inhibited the formation of hydroxylated products, but promoted the formation of the nitro derivative and the dimeric products. In UV/PDS, bicarbonate increased the formation of the nitro derivative and the dimeric products, but decreased the formation of the hydroxylated dimeric products. The different effect of bicarbonate on transformation products in UV/H 2 O 2 vs. UV/PDS suggested that carbonate radical (CO 3 - ) oxidized SMX through the electron transfer mechanism similar to SO 4 - but with less oxidation capacity. Additionally, SO 4 - and CO 3 - exhibited higher reactivity to the oxazole ring than the isoxazole ring of SMX. Ecotoxicity of transformation products was estimated by ECOSAR program based on the quantitative structure-activity relationship analysis as well as by experiments using

[Cleavage of DNA fragments induced by UV nanosecond laser excitation at 193 nm].

Science.gov (United States)

Vtiurina, N N; Grokhovskiĭ, S L; Filimonov, I V; Medvedkov, O I; Nechipurenko, D Iu; Vasil'ev, S A; Nechipurenko, Iu D

2011-01-01

The cleavage of dsDNA fragments in aqueous solution after irradiation with UV laser pulses at 193 nm has been studied. Samples were investigated using polyacrylamide gel electrophoresis. The intensity of damage of particular phosphodiester bond after hot alkali treatment was shown to depend on the base pair sequence. It was established that the probability of cleavage is twice higher for sites of DNA containing two or more successively running guanine residues. A possible mechanism of damage to the DNA molecule connected with the migration of holes along the helix is discussed.

Uniquely Strongly Clean Group Rings

Institute of Scientific and Technical Information of China (English)

WANG XIU-LAN

2012-01-01

A ring R is called clean if every element is the sum of an idempotent and a unit,and R is called uniquely strongly clean (USC for short) if every element is uniquely the sum of an idempotent and a unit that commute.In this article,some conditions on a ring R and a group G such that RG is clean are given.It is also shown that if G is a locally finite group,then the group ring RG is USC if and only if R is USC,and G is a 2-group.The left uniquely exchange group ring,as a middle ring of the uniquely clean ring and the USC ring,does not possess this property,and so does the uniquely exchange group ring.

Neutron activation studies of trace elements in tree rings

International Nuclear Information System (INIS)

Tout, R.E.; Gilboy, W.B.; Spyrou, N.M.

1977-01-01

The levels of twelve elements most of which are either considered essential to plant growth or have been detected in air filter samples in an air pollution survey have been monitored in three transverse sections of trees, two elms (ring-porous trees) and one cedar (a conifer). An irradiation time of 10 minutes and a waiting time of 1 minute were selected followed by a 10-minute count. The activated samples were placed on a specially shaped perspex disc situated on a 45-cm 3 Ge(Li) detector. The gamma-ray spectra were subsequently analysed on a 6600 computer, using the library program 'SAMPO' to which subroutines have been added for peak identification and for calculating the mass of elements present. All irradiations were carried out using a thermal neutron flux of 1.5x10 12 ncm -2 sec -1 . Two dimensional distributions of the elements around the tree rings of the section and radially from ring to ring, have been obtained to see if tree rings can be analysed for use as a record of historical pollution. Definite movement of most of these elements between the two main parts of the xylem has occured in all three trees. This makes it seem unlikely that any pollution products taken up from the atmosphere would be retained in the same ring in which they were originally accumulated. Exceptions may occur in the sapwood rings, where a few elements, especially Cl, show directional peaks which do not persist in the heartwood. (T.G.)

High-resolution characterization of sequence signatures due to non-random cleavage of cell-free DNA.

Science.gov (United States)

Chandrananda, Dineika; Thorne, Natalie P; Bahlo, Melanie

2015-06-17

High-throughput sequencing of cell-free DNA fragments found in human plasma has been used to non-invasively detect fetal aneuploidy, monitor organ transplants and investigate tumor DNA. However, many biological properties of this extracellular genetic material remain unknown. Research that further characterizes circulating DNA could substantially increase its diagnostic value by allowing the application of more sophisticated bioinformatics tools that lead to an improved signal to noise ratio in the sequencing data. In this study, we investigate various features of cell-free DNA in plasma using deep-sequencing data from two pregnant women (>70X, >50X) and compare them with matched cellular DNA. We utilize a descriptive approach to examine how the biological cleavage of cell-free DNA affects different sequence signatures such as fragment lengths, sequence motifs at fragment ends and the distribution of cleavage sites along the genome. We show that the size distributions of these cell-free DNA molecules are dependent on their autosomal and mitochondrial origin as well as the genomic location within chromosomes. DNA mapping to particular microsatellites and alpha repeat elements display unique size signatures. We show how cell-free fragments occur in clusters along the genome, localizing to nucleosomal arrays and are preferentially cleaved at linker regions by correlating the mapping locations of these fragments with ENCODE annotation of chromatin organization. Our work further demonstrates that cell-free autosomal DNA cleavage is sequence dependent. The region spanning up to 10 positions on either side of the DNA cleavage site show a consistent pattern of preference for specific nucleotides. This sequence motif is present in cleavage sites localized to nucleosomal cores and linker regions but is absent in nucleosome-free mitochondrial DNA. These background signals in cell-free DNA sequencing data stem from the non-random biological cleavage of these fragments. This

Oxidative cleavage of the octyl side chain of 1-(3,4-dichlorobenzyl)-5-octylbiguanide (OPB-2045) in rat and dog liver preparations.

Science.gov (United States)

Umehara, K; Kudo, S; Hirao, Y; Morita, S; Uchida, M; Odomi, M; Miyamoto, G

2000-08-01

The metabolism of 1-(3,4-dichlorobenzyl)-5-octylbiguanide (OPB-2045), a new potent biguanide antiseptic, was investigated using rat and dog liver preparations to elucidate the mechanism of OPB-2045 metabolite formation, in which the octyl side chain is reduced to four, five, or six carbon atoms. Chemical structures of metabolites were characterized by 1H NMR, fast atom bombardment/mass spectrometry, and liquid chromatography/electrospray ionization-tandem mass spectrometry. Three main metabolites were observed during incubation of OPB-2045 with rat liver S9: 2-octanol (M-1), 3-octanol (M-2), and 4-octanol (M-3). In the incubation of OPB-2045 with dog liver S9, eight metabolites were observed, seven of which being M-1, M-2, M-3, 2-octanone (M-4), threo-2,3-octandiol (M-5), erythro-2,3-octandiol (M-6), and 1,2-octandiol (M-7). M-5 and M-6 were further biotransformed to a ketol derivative and C-C bond cleavage metabolite (hexanoic acid derivative), an in vivo end product, in the incubation with dog liver microsomes. The reactions required NADPH as a cofactor and were significantly inhibited by the various inhibitors of cytochrome P450 (i.e., CO, n-octylamine, SKF 525-A, metyrapone, and alpha-naphthoflavone). The results indicate that the degraded products of OPB-2045 are produced by C-C bond cleavage after monohydroxylation, dihydroxylation, and ketol formation at the site of the octyl side chain with possible involvement of cytochrome P450 systems. This aliphatic C-C bond cleavage by sequential oxidative reactions may play an important role in the metabolism of other drugs or endogenous compounds that possess aliphatic chains.

Embryo apoptosis identification: Oocyte grade or cleavage stage?

Science.gov (United States)

Bakri, Noraina Mohd; Ibrahim, Siti Fatimah; Osman, Nurul Atikah; Hasan, Nurhaslina; Jaffar, Farah Hanan Fathihah; Rahman, Zulaiha Abdul; Osman, Khairul

2015-01-01

Apoptosis is a programed cell death that is vital for tissue homeostasis. However, embryo apoptosis had been known to be related to embryo fragmentation which should be avoided in in vitro fertilization (IVF). The purpose of this study was to evaluate the relationship of embryo apoptosis with the grade of immature oocytes and cleavage stage of in vitro produced (IVP) cattle embryos. This study consisted of 345 oocytes collected through ovary slicing. Immature oocytes were graded as A, B and C. This grading was based on cumulus cell thickness and compactness. All oocytes then underwent an in vitro maturation (IVM) procedure. An IVF was done 24 h after IVM culture. Prior to staining, stage of cleaved embryos was determined and classified as either 2, 4, 8 or >8-cell embryo stage. Apoptosis status of cleaved IVP embryos was determined by using annexin V-FITC staining technique at 48 and 72 h post insemination (hpi). Apoptosis status for each embryo was classified as either early or late. The result showed that there was no significant difference (p > 0.05) of apoptosis status among grade A, B and C embryos. All grades of oocytes showed embryo apoptosis where 1.5% late apoptosis for grade A, 4.5% and 10.4% of early and late apoptosis for grade B and grade C. Early apoptosis was not seen in grade A embryo. We also noted no significant difference (p > 0.05) of apoptosis status between 2, 4, 8 and >8-cell embryo stage. Early apoptosis was also not seen in >8-cell stage. Even though there were no differences in apoptosis expression between the three classes, the cleavage rate of grade A oocytes was significantly higher (p < 0.01) than grade B and grade C. In conclusion, the apoptosis expression in the embryo can occur regardless of the oocyte quality and the cleavage stage of the embryo produced. PMID:26858565

Ring rotational speed trend analysis by FEM approach in a Ring Rolling process

Science.gov (United States)

Allegri, G.; Giorleo, L.; Ceretti, E.

2018-05-01

Ring Rolling is an advanced local incremental forming technology to fabricate directly precise seamless ring-shape parts with various dimensions and materials. In this process two different deformations occur in order to reduce the width and the height of a preform hollow ring; as results a diameter expansion is obtained. In order to guarantee a uniform deformation, the preform is forced toward the Driver Roll whose aim is to transmit the rotation to the ring. The ring rotational speed selection is fundamental because the higher is the speed the higher will be the axial symmetry of the deformation process. However, it is important to underline that the rotational speed will affect not only the final ring geometry but also the loads and energy needed to produce it. Despite this importance in industrial environment, usually, a constant value for the Driver Roll angular velocity is set so to result in a decreasing trend law for the ring rotational speed. The main risk due to this approach is not fulfilling the axial symmetric constrain (due to the diameter expansion) and to generate a high localized ring section deformation. In order to improve the knowledge about this topic in the present paper three different ring rotational speed trends (constant, linearly increasing and linearly decreasing) were investigated by FEM approach. Results were compared in terms of geometrical and dimensional analysis, loads and energies required.

Mechanical improvement of metal reinforcement rings for a finite ring-shaped superconducting bulk

Science.gov (United States)

Huang, Chen-Guang; Zhou, You-He

2018-03-01

As a key technique, reinforcement of type-II superconducting bulks with metal rings can efficiently improve their mechanical properties to enhance the maximum trapped field. In this paper, we study the magnetostrictive and fracture behaviors of a finite superconducting ring bulk reinforced by three typical reinforcing structures composed of metal rings during the magnetizing process by means of the minimization of magnetic energy and the finite element method. After a field-dependent critical current density is adopted, the magnetostriction, pinning-induced stress, and crack tip stress intensity factor are calculated considering the demagnetization effects. The results show that the mechanical properties of the ring bulk are strongly dependent on the reinforcing structure and the material and geometrical parameters of the metal rings. Introducing the metal ring can significantly reduce the hoop stress, and the reduction effect by internal reinforcement is much improved relative to external reinforcement. By comparison, bilateral reinforcement seems to be the best candidate structure. Only when the metal rings have particular Young's modulus and radial thickness will they contribute to improve the mechanical properties the most. In addition, if an edge crack is pre-existing in the ring bulk, the presence of metal rings can effectively avoid crack propagation since it reduces the crack tip stress intensity factor by nearly one order of magnitude.

Laccase: microbial sources, production, purification, and potential biotechnological applications.

Science.gov (United States)

Shraddha; Shekher, Ravi; Sehgal, Simran; Kamthania, Mohit; Kumar, Ajay

2011-01-01

Laccase belongs to the blue multicopper oxidases and participates in cross-linking of monomers, degradation of polymers, and ring cleavage of aromatic compounds. It is widely distributed in higher plants and fungi. It is present in Ascomycetes, Deuteromycetes and Basidiomycetes and abundant in lignin-degrading white-rot fungi. It is also used in the synthesis of organic substance, where typical substrates are amines and phenols, the reaction products are dimers and oligomers derived from the coupling of reactive radical intermediates. In the recent years, these enzymes have gained application in the field of textile, pulp and paper, and food industry. Recently, it is also used in the design of biosensors, biofuel cells, as a medical diagnostics tool and bioremediation agent to clean up herbicides, pesticides and certain explosives in soil. Laccases have received attention of researchers in the last few decades due to their ability to oxidize both phenolic and nonphenolic lignin-related compounds as well as highly recalcitrant environmental pollutants. It has been identified as the principal enzyme associated with cuticular hardening in insects. Two main forms have been found: laccase-1 and laccase-2. This paper reviews the occurrence, mode of action, general properties, production, applications, and immobilization of laccases within different industrial fields.

Laccase: Microbial Sources, Production, Purification, and Potential Biotechnological Applications

Directory of Open Access Journals (Sweden)

Shraddha

2011-01-01

Full Text Available Laccase belongs to the blue multicopper oxidases and participates in cross-linking of monomers, degradation of polymers, and ring cleavage of aromatic compounds. It is widely distributed in higher plants and fungi. It is present in Ascomycetes, Deuteromycetes and Basidiomycetes and abundant in lignin-degrading white-rot fungi. It is also used in the synthesis of organic substance, where typical substrates are amines and phenols, the reaction products are dimers and oligomers derived from the coupling of reactive radical intermediates. In the recent years, these enzymes have gained application in the field of textile, pulp and paper, and food industry. Recently, it is also used in the design of biosensors, biofuel cells, as a medical diagnostics tool and bioremediation agent to clean up herbicides, pesticides and certain explosives in soil. Laccases have received attention of researchers in the last few decades due to their ability to oxidize both phenolic and nonphenolic lignin-related compounds as well as highly recalcitrant environmental pollutants. It has been identified as the principal enzyme associated with cuticular hardening in insects. Two main forms have been found: laccase-1 and laccase-2. This paper reviews the occurrence, mode of action, general properties, production, applications, and immobilization of laccases within different industrial fields.

Ring correlations in random networks.

Science.gov (United States)

Sadjadi, Mahdi; Thorpe, M F

2016-12-01

We examine the correlations between rings in random network glasses in two dimensions as a function of their separation. Initially, we use the topological separation (measured by the number of intervening rings), but this leads to pseudo-long-range correlations due to a lack of topological charge neutrality in the shells surrounding a central ring. This effect is associated with the noncircular nature of the shells. It is, therefore, necessary to use the geometrical distance between ring centers. Hence we find a generalization of the Aboav-Weaire law out to larger distances, with the correlations between rings decaying away when two rings are more than about three rings apart.

Design considerations for a feedback system to control self-bunching in ion-storage rings

International Nuclear Information System (INIS)

Ziemann, V.

2001-02-01

We discuss the feasibility of a feedback system to cure self-bunching of the electron-cooled coasting ion-beam in CELSIUS. Such a system may also aid stable operation of accumulator rings for future spallation neutron sources or heavy ion rings used for inertial fusion energy production

Characterization of cleavage events in the multifunctional cilium adhesin Mhp684 (P146) reveals a mechanism by which Mycoplasma hyopneumoniae regulates surface topography.

Science.gov (United States)

Bogema, Daniel R; Deutscher, Ania T; Woolley, Lauren K; Seymour, Lisa M; Raymond, Benjamin B A; Tacchi, Jessica L; Padula, Matthew P; Dixon, Nicholas E; Minion, F Chris; Jenkins, Cheryl; Walker, Mark J; Djordjevic, Steven P

2012-01-01

Mycoplasma hyopneumoniae causes enormous economic losses to swine production worldwide by colonizing the ciliated epithelium in the porcine respiratory tract, resulting in widespread damage to the mucociliary escalator, prolonged inflammation, reduced weight gain, and secondary infections. Protein Mhp684 (P146) comprises 1,317 amino acids, and while the N-terminal 400 residues display significant sequence identity to the archetype cilium adhesin P97, the remainder of the molecule is novel and displays unusual motifs. Proteome analysis shows that P146 preprotein is endogenously cleaved into three major fragments identified here as P50(P146), P40(P146), and P85(P146) that reside on the cell surface. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) identified a semitryptic peptide that delineated a major cleavage site in Mhp684. Cleavage occurred at the phenylalanine residue within sequence (672)ATEF↓QQ(677), consistent with a cleavage motif resembling S/T-X-F↓X-D/E recently identified in Mhp683 and other P97/P102 family members. Biotinylated surface proteins recovered by avidin chromatography and separated by two-dimensional gel electrophoresis (2-D GE) showed that more-extensive endoproteolytic cleavage of P146 occurs. Recombinant fragments F1(P146)-F3(P146) that mimic P50(P146), P40(P146), and P85(P146) were constructed and shown to bind porcine epithelial cilia and biotinylated heparin with physiologically relevant affinity. Recombinant versions of F3(P146) generated from M. hyopneumoniae strain J and 232 sequences strongly bind porcine plasminogen, and the removal of their respective C-terminal lysine and arginine residues significantly reduces this interaction. These data reveal that P146 is an extensively processed, multifunctional adhesin of M. hyopneumoniae. Extensive cleavage coupled with variable cleavage efficiency provides a mechanism by which M. hyopneumoniae regulates protein topography. Vaccines used to control Mycoplasma

Alpha - Skew Pi - Armendariz Rings

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Areej M Abduldaim

2018-03-01

Full Text Available In this article we introduce a new concept called Alpha-skew Pi-Armendariz rings (Alpha - S Pi - ARas a generalization of the notion of Alpha-skew Armendariz rings.Another important goal behind studying this class of rings is to employ it in order to design a modern algorithm of an identification scheme according to the evolution of using modern algebra in the applications of the field of cryptography.We investigate general properties of this concept and give examples for illustration. Furthermore, this paperstudy the relationship between this concept and some previous notions related to Alpha-skew Armendariz rings. It clearly presents that every weak Alpha-skew Armendariz ring is Alpha-skew Pi-Armendariz (Alpha-S Pi-AR. Also, thisarticle showsthat the concepts of Alpha-skew Armendariz rings and Alpha-skew Pi- Armendariz rings are equivalent in case R is 2-primal and semiprime ring.Moreover, this paper proves for a semicommutative Alpha-compatible ringR that if R[x;Alpha] is nil-Armendariz, thenR is an Alpha-S Pi-AR. In addition, if R is an Alpha - S Pi -AR, 2-primal and semiprime ring, then N(R[x;Alpha]=N(R[x;Alpha]. Finally, we look forwardthat Alpha-skew Pi-Armendariz rings (Alpha-S Pi-ARbe more effect (due to their properties in the field of cryptography than Pi-Armendariz rings, weak Armendariz rings and others.For these properties and characterizations of the introduced concept Alpha-S Pi-AR, we aspire to design a novel algorithm of an identification scheme.

Dual CRISPR-Cas9 Cleavage Mediated Gene Excision and Targeted Integration in Yarrowia lipolytica.

Science.gov (United States)

Gao, Difeng; Smith, Spencer; Spagnuolo, Michael; Rodriguez, Gabriel; Blenner, Mark

2018-05-29

CRISPR-Cas9 technology has been successfully applied in Yarrowia lipolytica for targeted genomic editing including gene disruption and integration; however, disruptions by existing methods typically result from small frameshift mutations caused by indels within the coding region, which usually resulted in unnatural protein. In this study, a dual cleavage strategy directed by paired sgRNAs is developed for gene knockout. This method allows fast and robust gene excision, demonstrated on six genes of interest. The targeted regions for excision vary in length from 0.3 kb up to 3.5 kb and contain both non-coding and coding regions. The majority of the gene excisions are repaired by perfect nonhomologous end-joining without indel. Based on this dual cleavage system, two targeted markerless integration methods are developed by providing repair templates. While both strategies are effective, homology mediated end joining (HMEJ) based method are twice as efficient as homology recombination (HR) based method. In both cases, dual cleavage leads to similar or improved gene integration efficiencies compared to gene excision without integration. This dual cleavage strategy will be useful for not only generating more predictable and robust gene knockout, but also for efficient targeted markerless integration, and simultaneous knockout and integration in Y. lipolytica. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cas9-catalyzed DNA Cleavage Generates Staggered Ends: Evidence from Molecular Dynamics Simulations

Science.gov (United States)

Zuo, Zhicheng; Liu, Jin

2016-11-01

The CRISPR-associated endonuclease Cas9 from Streptococcus pyogenes (spCas9) along with a single guide RNA (sgRNA) has emerged as a versatile toolbox for genome editing. Despite recent advances in the mechanism studies on spCas9-sgRNA-mediated double-stranded DNA (dsDNA) recognition and cleavage, it is still unclear how the catalytic Mg2+ ions induce the conformation changes toward the catalytic active state. It also remains controversial whether Cas9 generates blunt-ended or staggered-ended breaks with overhangs in the DNA. To investigate these issues, here we performed the first all-atom molecular dynamics simulations of the spCas9-sgRNA-dsDNA system with and without Mg2+ bound. The simulation results showed that binding of two Mg2+ ions at the RuvC domain active site could lead to structurally and energetically favorable coordination ready for the non-target DNA strand cleavage. Importantly, we demonstrated with our simulations that Cas9-catalyzed DNA cleavage produces 1-bp staggered ends rather than generally assumed blunt ends.

Plasma-ring, fast-opening switch

International Nuclear Information System (INIS)

Hartman, C.W.; Eddleman, J.; Hammer, J.H.

1986-01-01

The authors discuss a fast-opening switch concept based on magnetically confined plasma rings, PROS (for Plasma Ring Opening Switch). In PROS, the plasma ring, confined by Bθ /sub and B/poloidal /sub fields of a compact torus, provide a low mass, localized conduction path between coaxial electrodes. To operate the switch, driver current is passed across the electrodes through the ring, storing inductive energy in external inductance and between the electrodes on the driver side of the ring. The ring is accelerated away from the driver by the field of the driver current and passes over a load gap transferring the current to the load. The authors distinguish two configurations in PROS, straight PROS where the electrodes are coaxial cylinders, and cone PROS with conical electrodes. In straight PROS ring acceleration takes place during the inductive store period as in foil switches, but with the localized ring providing the current path. Increased performance is predicted for the cone PROS (see figure) which employs compression of the ring in the cone during the inductive store period. Here, the B/θ /sub field of the driver forces the ring towards the apex of the cone but the force is in near balance with the opposing component of the radial equilibrium force of the ring along the cone. As a result, the ring undergoes a slow, quasistatic compression limited only by resistive decay of the ring field. Slow compression allows inductive storage with low-power drivers (homopoloar, magneto cumulative generators, high C-low V capacitor banks, etc.). Near the apex of the cone, near peak compression, the ring is allowed to enter a straight coaxial section where, because of low-mass, it rapidly accelerates to high velocity and crosses the load gap

Ring cavity surface emitting semiconductor lasers

International Nuclear Information System (INIS)

Mujagic, E.

2010-01-01

Quantum cascade lasers (QCLs) are electrically driven semiconductor lasers, which have undergone a steady improvement since the first demonstration in 1994. These are now well established as reliable sources of coherent light in the mid-infrared (MIR) and terahertz (THz)range of the electromagnetic spectrum (3-300 μm). The rapid progress of this type of lasers is based on a high degree of freedom in tailoring the emission wavelength within a large variety of semiconductor heterostructure designs and materials. These properties have attracted the attention of various applications such as gas analysis, chemical sensing, spectral imaging and free-space telecommunication. In order to improve the selectivity, sensitivity and efficiency of today's sensor systems, high optical power, continuous wave and room temperature performance, single-mode operation and low divergence optical beams, are highly desirable qualities of a compact laser source in this field of research. Since all of these features cannot be provided by a conventional edge-emitting device at the same time, research has put focus on the development of surface emitting devices. Nowadays, the vertical cavity surface emitting lasers (VCSELs) are the most prominent representative for this type of light emitters. With its capability of producing narrow circular beams, the feasibility of two-dimensional arrays and on-wafer testing, such a coherent light source results in a reduction of the fabrication effort and production costs. Since the radiation in QCLs is strictly polarized normal to the epitaxial layer plane, fabrication of VCSELs based on QC structures is not viable. The subject of this work is the design and realization of 'ring cavity surface emitting lasers' (ring-CSELs). This type of lasers employs a circular ring cavity and a resonant distributed feedback (DFB) surface grating. Ring-CSELs were fabricated on the basis of MIR and THz QC structures, which cover a wavelength range from 4 μm to 93 �

PhnY and PhnZ comprise a new oxidative pathway for enzymatic cleavage of a carbon-phosphorus bond

DEFF Research Database (Denmark)

McSorley, Fern R.; Wyatt, Peter W.; Martinez, Ascuncion

2012-01-01

The sequential activities of PhnY, an α-ketoglutarate/Fe(II)-dependent dioxygenase, and PhnZ, a Fe(II)-dependent enzyme of the histidine-aspartate motif hydrolase family, cleave the carbon-phosphorus bond of the organophosphonate natural product 2-aminoethylphosphonic acid. PhnY adds a hydroxyl...... group to the α-carbon, yielding 2-amino-1-hydroxyethylphosphonic acid, which is oxidatively converted by PhnZ to inorganic phosphate and glycine. The PhnZ reaction represents a new enzyme mechanism for metabolic cleavage of a carbon-phosphorus bond....

Fusion Rings for Quantum Groups

DEFF Research Database (Denmark)

Andersen, Henning Haahr; Stroppel, Catharina

2014-01-01

We study the fusion rings of tilting modules for a quantum group at a root of unity modulo the tensor ideal of negligible tilting modules. We identify them in type A with the combinatorial rings from Korff, C., Stroppel, C.: The sl(ˆn)k-WZNW fusion ring: a combinato-rial construction...... and a realisation as quotient of quantum cohomology. Adv. Math. 225(1), 200–268, (2010) and give a similar description of the sp2n-fusion ring in terms of non-commutative symmetric functions. Moreover we give a presentation of all fusion rings in classical types as quotients of polynomial rings. Finally we also...... compute the fusion rings for type G2....

A Study of Storage Ring Requirements for an Explosive Detection System Using NRA Method.

Energy Technology Data Exchange (ETDEWEB)

Wang, T. F. (Tai-Sen F.); Kwan, T. J. T. (Thomas J. T.)

2005-01-01

The technical feasibility of an explosives detection system based on the nuclear resonance absorption (NRA) of gamma rays in nitrogen-rich materials was demonstrated at Los Alamos National Laboratory (LANL) in 1993 by using an RFQ proton accelerator and a tomographic imaging prototype. The study is being continued recently to examine deployment of such an active interrogation system in realistic scenarios. The approach is to use an accelerator and electron-cooling-equipped storage rings(s) to provide the high quality and high current proton beam needed in a practical application. In this work, we investigate the requirements on the storage ring(s) with external gamma-ray-production target for a variant of the airport luggage inspection system considered in the earlier LANL experiments. Estimations are carried out based on the required inspection throughput, the gamma ray yield, the proton beam emittance growth due to scatters with the photon-production target, beam current limit in the storage ring, and the electron-cooling rate. Studies using scaling and reasonable parameter values indicate that it is possible to use no more than a few storage rings per inspection station in a practical NRA luggage inspection complex having more than ten inspection stations.

Remote Stereoinductive Intramolecular Nitrile Oxide Cycloaddition: Asymmetric Total Synthesis and Structure Revision of (-)-11β-Hydroxycurvularin.

Science.gov (United States)

Choe, Hyeonjeong; Pham, Thuy Trang; Lee, Joo Yun; Latif, Muhammad; Park, Haeil; Kang, Young Kee; Lee, Jongkook

2016-03-18

The first total synthesis and structure revision of (-)-11β-hydroxycurvularin (1b), a macrolide possessing a β-hydroxyketone moiety, were accomplished. The β-hydroxyketone moiety in this natural product was introduced by cleavage of the N-O bond in an isoxazoline ring that was formed diastereoselectively in a 1,5-remote stereocontrolled fashion by employing intramolecular nitrile oxide cycloaddition.

The LSU Electron Storage Ring, the first commercially-built storage ring

International Nuclear Information System (INIS)

Sah, R.

1990-01-01

The Brobeck Division of Maxwell Laboratories, Inc., is building the first industrially-produced storage ring. It will be located at Louisiana State University (LSU) at the Center for Advanced Microstructures and Devices (CAMD) in Baton Rouge. The purpose of this electron storage ring is to provide intense beams of x-rays to advance the state-of-the-art in lithography and to permit research in a broad area. This facility consists of a 1.2 GeV, 400 mA electron storage ring with a 200 MeV linac injector. The magnet lattice is a Chasman-Green design (double-bend achromat), and the ring circumference is 55.2 meters. There are four 3.0 meter, dispersion-free straight sections, one for injection, one for the 500 MHz RF cavity, and two for possible future insertion devices. The storge ring construction project is in the detailed-design stage, and many systems are in the initial stages of fabrication. 4 figs., 1 tab

Fusion rings and fusion ideals

DEFF Research Database (Denmark)

Andersen, Troels Bak

by the so-called fusion ideals. The fusion rings of Wess-Zumino-Witten models have been widely studied and are well understood in terms of precise combinatorial descriptions and explicit generating sets of the fusion ideals. They also appear in another, more general, setting via tilting modules for quantum......This dissertation investigates fusion rings, which are Grothendieck groups of rigid, monoidal, semisimple, abelian categories. Special interest is in rational fusion rings, i.e., fusion rings which admit a finite basis, for as commutative rings they may be presented as quotients of polynomial rings...

Predictors of hepatitis B cure using gene therapy to deliver DNA cleavage enzymes: a mathematical modeling approach.

Directory of Open Access Journals (Sweden)

Joshua T Schiffer

Full Text Available Most chronic viral infections are managed with small molecule therapies that inhibit replication but are not curative because non-replicating viral forms can persist despite decades of suppressive treatment. There are therefore numerous strategies in development to eradicate all non-replicating viruses from the body. We are currently engineering DNA cleavage enzymes that specifically target hepatitis B virus covalently closed circular DNA (HBV cccDNA, the episomal form of the virus that persists despite potent antiviral therapies. DNA cleavage enzymes, including homing endonucleases or meganucleases, zinc-finger nucleases (ZFNs, TAL effector nucleases (TALENs, and CRISPR-associated system 9 (Cas9 proteins, can disrupt specific regions of viral DNA. Because DNA repair is error prone, the virus can be neutralized after repeated cleavage events when a target sequence becomes mutated. DNA cleavage enzymes will be delivered as genes within viral vectors that enter hepatocytes. Here we develop mathematical models that describe the delivery and intracellular activity of DNA cleavage enzymes. Model simulations predict that high vector to target cell ratio, limited removal of delivery vectors by humoral immunity, and avid binding between enzyme and its DNA target will promote the highest level of cccDNA disruption. Development of de novo resistance to cleavage enzymes may occur if DNA cleavage and error prone repair does not render the viral episome replication incompetent: our model predicts that concurrent delivery of multiple enzymes which target different vital cccDNA regions, or sequential delivery of different enzymes, are both potentially useful strategies for avoiding multi-enzyme resistance. The underlying dynamics of cccDNA persistence are unlikely to impact the probability of cure provided that antiviral therapy is given concurrently during eradication trials. We conclude by describing experiments that can be used to validate the model, which

Active site mutations change the cleavage specificity of neprilysin.

Directory of Open Access Journals (Sweden)

Travis Sexton

Full Text Available Neprilysin (NEP, a member of the M13 subgroup of the zinc-dependent endopeptidase family is a membrane bound peptidase capable of cleaving a variety of physiological peptides. We have generated a series of neprilysin variants containing mutations at either one of two active site residues, Phe(563 and Ser(546. Among the mutants studied in detail we observed changes in their activity towards leucine(5-enkephalin, insulin B chain, and amyloid β(1-40. For example, NEP(F563I displayed an increase in preference towards cleaving leucine(5-enkephalin relative to insulin B chain, while mutant NEP(S546E was less discriminating than neprilysin. Mutants NEP(F563L and NEP(S546E exhibit different cleavage site preferences than neprilysin with insulin B chain and amyloid ß(1-40 as substrates. These data indicate that it is possible to alter the cleavage site specificity of neprilysin opening the way for the development of substrate specific or substrate exclusive forms of the enzyme with enhanced therapeutic potential.

PROSPECTS OF MANUFACTURE OF PISTON RINGS INTERNAL COMBUSTION ENGINES OF POWDER MATERIALS ON THE BASE OF IRON

Directory of Open Access Journals (Sweden)

B. M. Musaibov

2013-01-01

Full Text Available Development and production of piston rings made of sintered materials on the basis of iron powder metallurgy is an innovative way. In the application of this technology reduces the consumption of material and costs for the production of piston rings 30-40% in comparison with the traditional methods of their manufacture

Cleavage of thymine N3-H bonds by low-energy electrons attached to base π* orbitals

International Nuclear Information System (INIS)

Theodore, Magali; Sobczyk, Monika; Simons, Jack

2006-01-01

In this work, we extend our earlier studies on single strand break (SSB) formation in DNA to consider the possibility of cleaving a thymine N 3 -H bond to generate a nitrogen-centered anion and a hydrogen radical which might proceed to induce further bond cleavages. In earlier studies, we considered SSBs induced by low-energy electrons that attach to DNA bases' π* orbitals or to phosphate P=O π* orbitals to cleave sugar-phosphate C-O bonds or base-sugar N 1 -C bonds. We also studied the effects of base π-stacking on the rates of such bond cleavages. To date, our results suggest that sugar-phosphate C-O bonds have the lowest barriers to cleavage, that attachment of electrons with energies below 2 eV most likely occurs at the base π* orbitals, that electrons with energy above 2 eV can also attach to phosphate P=O π* orbitals, and that base π stacking has a modest but slowing effect on the rates of SSB formation. However, we had not yet examined the possibility that base N 3 -H bonds could rupture subsequent to base π* orbital capture. In the present work, the latter possibility is considered and it is found that the barrier to cleavage of the N 3 -H bond in thymine is considerably higher than for cleaving sugar-phosphate C-O bonds, so our prediction that SSB formation is dominated by C-O bond cleavage remains intact

Effects of Olive Metabolites on DNA Cleavage Mediated by Human Type II Topoisomerases

Science.gov (United States)

2016-01-01

Several naturally occurring dietary polyphenols with chemopreventive or anticancer properties are topoisomerase II poisons. To identify additional phytochemicals that enhance topoisomerase II-mediated DNA cleavage, a library of 341 Mediterranean plant extracts was screened for activity against human topoisomerase IIα. An extract from Phillyrea latifolia L., a member of the olive tree family, displayed high activity against the human enzyme. On the basis of previous metabolomics studies, we identified several polyphenols (hydroxytyrosol, oleuropein, verbascoside, tyrosol, and caffeic acid) as potential candidates for topoisomerase II poisons. Of these, hydroxytyrosol, oleuropein, and verbascoside enhanced topoisomerase II-mediated DNA cleavage. The potency of these olive metabolites increased 10–100-fold in the presence of an oxidant. Hydroxytyrosol, oleuropein, and verbascoside displayed hallmark characteristics of covalent topoisomerase II poisons. (1) The activity of the metabolites was abrogated by a reducing agent. (2) Compounds inhibited topoisomerase II activity when they were incubated with the enzyme prior to the addition of DNA. (3) Compounds were unable to poison a topoisomerase IIα construct that lacked the N-terminal domain. Because hydroxytyrosol, oleuropein, and verbascoside are broadly distributed across the olive family, extracts from the leaves, bark, and fruit of 11 olive tree species were tested for activity against human topoisomerase IIα. Several of the extracts enhanced enzyme-mediated DNA cleavage. Finally, a commercial olive leaf supplement and extra virgin olive oils pressed from a variety of Olea europea subspecies enhanced DNA cleavage mediated by topoisomerase IIα. Thus, olive metabolites appear to act as topoisomerase II poisons in complex formulations intended for human dietary consumption. PMID:26132160

Photochemistry in Saturn’s Ring-Shadowed Atmosphere: Modulation of Hydrocarbons and Aerosols

Science.gov (United States)

Edgington, Scott G.; Atreya, Sushil K.; Wilson, Eric H.; Baines, Kevin H.; West, Robert A.; Bjoraker, Gordon L.; Fletcher, Leigh N.; Momary, Tom

2015-11-01

Cassini has been orbiting Saturn for over eleven years now. During this epoch, the ring shadow has moved from covering much of the northern hemisphere (the solar inclination was 24 degrees) to covering a large swath south of the equator and it continues to move southward. At Saturn Orbit Insertion in 2004, the projection of the A-ring onto Saturn reached as far as 40N along the central meridian (52N at the terminator). At its maximum extent, the ring shadow can reach as far as 48N/S (58N/S at the terminator). The net effect is that the intensity of both ultraviolet and visible sunlight penetrating through the rings to any particular latitude will vary depending on both Saturn’s axis relative to the Sun and the optical thickness of each ring system. In essence, the rings act like semi-transparent venetian blinds.Our previous work, examined the variation of the solar flux as a function of solar inclination, i.e. for each 7.25-year season at Saturn. Here, we report on the impact of the oscillating ring shadow on the photolysis and production rates of hydrocarbons (acetylene, ethane, propane, and benzene) and phosphine in Saturn’s stratosphere and upper troposphere. The impact of these production and loss rates on the abundance of long-lived photochemical products leading to haze formation are explored. Similarly, we assess their impact on phosphine abundance, a disequilibrium species whose presence in the upper troposphere can be used as a tracer of convective processes in the deeper atmosphere.We will also present our ongoing analysis of Cassini’s datasets that provide an estimate of the evolving haze content of the northern hemisphere and we will begin to assess the implications for dynamical mixing. In particular, we will examine how the now famous hexagonal jet stream acts like a barrier to transport, isolating Saturn’s north polar region from outside transport of photochemically-generated molecules and haze.The research described in this paper was carried

Evaluation of ring impedance of the Photon Factory storage ring

International Nuclear Information System (INIS)

Kiuchi, T.; Izawa, M.; Tokumoto, S.; Hori, Y.; Sakanaka, S.; Kobayashi, M.; Kobayakawa, H.

1992-05-01

The loss parameters of the ducts in the Photon Factory (PF) storage ring were evaluated using the wire method and the code TBCI. Both the measurement and the calculation were done for a different bunch length (σ) ranging from 23 to 80 ps. The PF ring impedance was estimated to be |Z/n|=3.2 Ω using the broadband impedance model. The major contribution to the impedance comes from the bellows and the gate valve sections. Improvements of these components will lower the ring impedance by half. (author)

Phenylpropanoid 2,3-dioxygenase involved in the cleavage of the ferulic acid side chain to form vanillin and glyoxylic acid in Vanilla planifolia.

Science.gov (United States)

Negishi, Osamu; Negishi, Yukiko

2017-09-01

Enzyme catalyzing the cleavage of the phenylpropanoid side chain was partially purified by ion exchange and gel filtration column chromatography after (NH 4 ) 2 SO 4 precipitation. Enzyme activities were dependent on the concentration of dithiothreitol (DTT) or glutathione (GSH) and activated by addition of 0.5 mM Fe 2+ . Enzyme activity for ferulic acid was as high as for 4-coumaric acid in the presence of GSH, suggesting that GSH acts as an endogenous reductant in vanillin biosynthesis. Analyses of the enzymatic reaction products with quantitative NMR (qNMR) indicated that an amount of glyoxylic acid (GA) proportional to vanillin was released from ferulic acid by the enzymatic reaction. These results suggest that phenylpropanoid 2,3-dioxygenase is involved in the cleavage of the ferulic acid side chain to form vanillin and GA in Vanilla planifolia.

The Generation of Dehydroalanine Residues in Protonated Polypeptides: Ion/Ion Reactions for Introducing Selective Cleavages

Science.gov (United States)

Peng, Zhou; Bu, Jiexun; McLuckey, Scott A.

2017-09-01

We examine a gas-phase approach for converting a subset of amino acid residues in polypeptide cations to dehydroalanine (Dha). Subsequent activation of the modified polypeptide ions gives rise to specific cleavage N-terminal to the Dha residue. This process allows for the incorporation of selective cleavages in the structural characterization of polypeptide ions. An ion/ion reaction within the mass spectrometer between a multiply protonated polypeptide and the sulfate radical anion introduces a radical site into the multiply protonated polypeptide reactant. Subsequent collisional activation of the polypeptide radical cation gives rise to radical side chain loss from one of several particular amino acid side chains (e.g., leucine, asparagine, lysine, glutamine, and glutamic acid) to yield a Dha residue. The Dha residues facilitate preferential backbone cleavages to produce signature c- and z-ions, demonstrated with cations derived from melittin, mechano growth factor (MGF), and ubiquitin. The efficiencies for radical side chain loss and for subsequent generation of specific c- and z-ions have been examined as functions of precursor ion charge state and activation conditions using cations of ubiquitin as a model for a small protein. It is noted that these efficiencies are not strongly dependent on ion trap collisional activation conditions but are sensitive to precursor ion charge state. Moderate to low charge states show the greatest overall yields for the specific Dha cleavages, whereas small molecule losses (e.g., water/ammonia) dominate at the lowest charge states and proton catalyzed amide bond cleavages that give rise to b- and y-ions tend to dominate at high charge states. [Figure not available: see fulltext.

ATP-Dependent C–F Bond Cleavage Allows the Complete Degradation of 4-Fluoroaromatics without Oxygen

Directory of Open Access Journals (Sweden)

Oliver Tiedt

2016-08-01

Full Text Available Complete biodegradation of the abundant and persistent fluoroaromatics requires enzymatic cleavage of an arylic C–F bond, probably the most stable single bond of a biodegradable organic molecule. While in aerobic microorganisms defluorination of fluoroaromatics is initiated by oxygenases, arylic C–F bond cleavage has never been observed in the absence of oxygen. Here, an oxygen-independent enzymatic aryl fluoride bond cleavage is described during the complete degradation of 4-fluorobenzoate or 4-fluorotoluene to CO2 and HF in the denitrifying Thauera aromatica: the ATP-dependent defluorination of 4-fluorobenzoyl-coenzyme A (4-F-BzCoA to benzoyl-coenzyme A (BzCoA and HF, catalyzed by class I BzCoA reductase (BCR. Adaptation to growth with the fluoroaromatics was accomplished by the downregulation of a promiscuous benzoate-CoA ligase and the concomitant upregulation of 4-F-BzCoA-defluorinating/dearomatizing BCR on the transcriptional level. We propose an unprecedented mechanism for reductive arylic C–F bond cleavage via a Birch reduction-like mechanism resulting in a formal nucleophilic aromatic substitution. In the proposed anionic 4-fluorodienoyl-CoA transition state, fluoride elimination to BzCoA is favored over protonation to a fluorinated cyclic dienoyl-CoA.

Tree Rings: Timekeepers of the Past.

Science.gov (United States)

Phipps, R. L.; McGowan, J.

One of a series of general interest publications on science issues, this booklet describes the uses of tree rings in historical and biological recordkeeping. Separate sections cover the following topics: dating of tree rings, dating with tree rings, tree ring formation, tree ring identification, sample collections, tree ring cross dating, tree…

Above‐ground woody carbon sequestration measured from tree rings is coherent with net ecosystem productivity at five eddy‐covariance sites

DEFF Research Database (Denmark)

Babst, Flurin; Bouriaud, Olivier; Papale, Dario

2014-01-01

Attempts to combine biometric and eddy‐covariance (EC) quantifications of carbon allocation to different storage pools in forests have been inconsistent and variably successful in the past. We assessed above‐ground biomass changes at five long‐term EC forest stations based on tree‐ring width...... and wood density measurements, together with multiple allometric models. Measurements were validated with site‐specific biomass estimates and compared with the sum of monthly CO2 fluxes between 1997 and 2009. Biometric measurements and seasonal net ecosystem productivity (NEP) proved largely compatible...

Dominant negative umuD mutations decreasing RecA-mediated cleavage suggest roles for intact UmuD in modulation of SOS mutagenesis

International Nuclear Information System (INIS)

Battista, J.R.; Ohta, Toshihiro; Nohmi, Takehiko; Sun, W.; Walker, G.C.

1990-01-01

The products of the SOS-regulated umuDC operon are required for most UV and chemical mutagenesis in Escherichia coli. The UmuD protein shares homology with a family of proteins that includes LexA and several bacteriophage repressors. UmuD is posttranslationally activated for its role n mutagenesis by a RecA-mediated proteolytic cleavage that yields UmuD'. A set of missense mutants of umuD was isolated and shown to encode mutant UmuD proteins that are deficient in RecA-mediated cleavage in vivo. Most of these mutations are dominant to umuD + with respect to UV mutagenesis yet do not interfere with SOS induction. Although both UmuD and UmuD' form homodimers, the authors provide evidence that they preferentially form heterodimers. The relationship of UmuD to LexA, λ repressor, and other members of the family of proteins is discussed and possible roles intact UmuD in modulating SOS mutagenesis are discussed

A Molecular Sensor To Characterize Arenavirus Envelope Glycoprotein Cleavage by Subtilisin Kexin Isozyme 1/Site 1 Protease

Science.gov (United States)

Oppliger, Joel; da Palma, Joel Ramos; Burri, Dominique J.; Khatib, Abdel-Majid; Spiropoulou, Christina F.

2015-01-01

ABSTRACT Arenaviruses are emerging viruses including several causative agents of severe hemorrhagic fevers in humans. The advent of next-generation sequencing technology has greatly accelerated the discovery of novel arenavirus species. However, for many of these viruses, only genetic information is available, and their zoonotic disease potential remains unknown. During the arenavirus life cycle, processing of the viral envelope glycoprotein precursor (GPC) by the cellular subtilisin kexin isozyme 1 (SKI-1)/site 1 protease (S1P) is crucial for productive infection. The ability of newly emerging arenaviruses to hijack human SKI-1/S1P appears, therefore, to be a requirement for efficient zoonotic transmission and human disease potential. Here we implement a newly developed cell-based molecular sensor for SKI-1/S1P to characterize the processing of arenavirus GPC-derived target sequences by human SKI-1/S1P in a quantitative manner. We show that only nine amino acids flanking the putative cleavage site are necessary and sufficient to accurately recapitulate the efficiency and subcellular location of arenavirus GPC processing. In a proof of concept, our sensor correctly predicts efficient processing of the GPC of the newly emergent pathogenic Lujo virus by human SKI-1/S1P and defines the exact cleavage site. Lastly, we employed our sensor to show efficient GPC processing of a panel of pathogenic and nonpathogenic New World arenaviruses, suggesting that GPC cleavage represents no barrier for zoonotic transmission of these pathogens. Our SKI-1/S1P sensor thus represents a rapid and robust test system for assessment of the processing of putative cleavage sites derived from the GPCs of newly discovered arenavirus by the SKI-1/S1P of humans or any other species, based solely on sequence information. IMPORTANCE Arenaviruses are important emerging human pathogens that can cause severe hemorrhagic fevers with high mortality in humans. A crucial step in productive arenavirus

Application research of ferrous matrix composites in roller ring used in high-speed wire/bar rolling mill

International Nuclear Information System (INIS)

Song Yanpei; Li Xiuqing; Bi Shuangxu

2010-01-01

Research highlights: → A composite structure roller rings was fabricated by centrifugal casting. → The roller rings consisted of outer WCP/Fe-C composites layer and inner Fe-C alloy matrix. → Hardness attained to HRA80-85 in the composites layer, and HRA73-76 in inner Fe-C alloy matrix where the toughness was over 8 J/cm 2 . → The wear resistance of the roller rings excelled that of high-speed steel, and approached to that of the WC hard alloy roll. → The production cost of the WCP/Fe-C composites roller ring decreased by 50%. - Abstract: Tungsten carbide particle (WC P ) reinforced ferrous matrix composites roller rings were fabricated by centrifugal casting. The microstructures, properties and application effect of the composites roller rings were investigated by SEM, TEM and various property testers. The experimental results show that the WC P were uniformly distributed in outer reinforced-layer (working-layer) of 20-50 mm in thickness and their volume fraction reached 60-80 vol.%; there was a good interface bonding between WC P and Fe-C alloy without any reaction products; hardness attained to HRA80-85 in working-layer, and HRA73-76 in inner ferrous matrix where the toughness was over 8 J/cm 2 ; the wear resistance of the composites roller rings excels that of high-speed steel; service life of the composites parts approached to that of the WC hard alloy roll when the same WC P -volume-fraction in working-layer were obtained for both of them, but the production cost of the WC P /Fe-C composites roller ring decreased by 50%.

Sequence specific inhibition of DNA restriction enzyme cleavage by PNA

DEFF Research Database (Denmark)

Nielsen, P.E.; Egholm, M.; Berg, R.H.

1993-01-01

Plasmids containing double-stranded 10-mer PNA (peptide nucleic acid chimera) targets proximally flanked by two restriction enzyme sites were challenged with the complementary PNA or PNAs having one or two mismatches, and the effect on the restriction enzyme cleavage of the flanking sites was ass...

Cleavage of desmin by cysteine proteases: Calpains and cathepsin B

DEFF Research Database (Denmark)

Baron, Caroline; Jacobsen, S.; Purslow, P.P.

2004-01-01

The intermediate filament protein, desmin, was purified from pork longissimus dorsi and incubated with either P-calpain, m-calpain or cathepsin B. Proteolysis of desmin was followed using SDS-PAGE and Western blotting. After incubation of desmin with the proteases, cleavage sites on the desmin mo...

Alzheimer's disease against peptides products of enzymatic cleavage APP protein: Biological, pathobiological and physico-chemical properties of fibrillating peptides.

Science.gov (United States)

Marszałek, Małgorzata

2017-05-17

Various peptides products of enzymatic cleavage of key for Alzheimer's disease Amyloid Precursor Protein (APP) are well known, but still are matter of scientific debate. The Aβ type products are especially challenging for experimental and medical research. This paper outlines several, still poorly known, biological and medical processes such as peptides biology, i.e., formation, biodistribution, translocation, transport and finally removal from brain compartments and body fluids like Intracellular Fluid (ICF), Cerebrospinal Fluid (CSF), Interstitial Fluid (ISF), blood serum or urine. In addition, the following studies concerning AD patients might prove challenging and simultaneously promising: peptides translocation through Blood-Brain - Barrier (BBB) and Blood-Cerebrospinal Fluid Barrier (BCSFB) and their removal from the brain according to a new concept of glymphatic system; - diagnostic difficulties that stem from physico-chemical properties and the nature of proteins or fibrillating peptides itself like low concentration, short half-live and from experimental-technical problems as well like high adsorption or low solubility of Aβ, tau or amylin. The study of diagnostic parameters is very important, as it may better reflect early changes before the disease develops; one such parameter is the Aβ42/Aβ40 ratio, or the ratio with the total tau concentration combination and other new biomarkers like Aβ1-38; other factors include oxidative stress and inflammation process proteins, complement factor H, alpha-2-macroglobulin, or clusterin. The study of various forms of pathological amyloid deposits that emerge in different but specific brain regions AD patients seems to be crucial as well. The composition of the first initial pathological, pre-fibrillating monomers of fibrillating peptides and their role in AD development and disease progression have been described as well. They are even more challenging for science and simultaneously might be more promising in

Workshop on compact storage ring technology: applications to lithography

International Nuclear Information System (INIS)

1986-01-01

Project planning in the area of x-ray lithography is discussed. Three technologies that are emphasized are the light source, the lithographic technology, and masking technology. The needs of the semiconductor industry in the lithography area during the next decade are discussed, particularly as regards large scale production of high density dynamic random access memory devices. Storage ring parameters and an overall exposure tool for x-ray lithography are addressed. Competition in this area of technology from Germany and Japan is discussed briefly. The design of a storage ring is considered, including lattice design, magnets, and beam injection systems

Some Aspects of Ring Theory

CERN Document Server

Herstein, IN

2011-01-01

S. Amitsur: Associative rings with identities.- I.N. Herstein: Topics in ring theory.- N. Jacobson: Representation theory of Jordan algebras.- I. Kaplansky: The theory of homological dimension.- D. Buchsbaum: Complexes in local ring theory.- P.H. Cohn: Two topics in ring theory.- A.W. Goldie: Non-commutative localisation.

Cleavage of sp3 C-O bonds via oxidative addition of C-H bonds.

Science.gov (United States)

Choi, Jongwook; Choliy, Yuriy; Zhang, Xiawei; Emge, Thomas J; Krogh-Jespersen, Karsten; Goldman, Alan S

2009-11-04

(PCP)Ir (PCP = kappa(3)-C(6)H(3)-2,6-[CH(2)P(t-Bu)(2)](2)) is found to undergo oxidative addition of the methyl-oxygen bond of electron-poor methyl aryl ethers, including methoxy-3,5-bis(trifluoromethyl)benzene and methoxypentafluorobenzene, to give the corresponding aryloxide complexes (PCP)Ir(CH(3))(OAr). Although the net reaction is insertion of the Ir center into the C-O bond, density functional theory (DFT) calculations and a significant kinetic isotope effect [k(CH(3))(OAr)/k(CD(3))(OAr) = 4.3(3)] strongly argue against a simple insertion mechanism and in favor of a pathway involving C-H addition and alpha-migration of the OAr group to give a methylene complex followed by hydride-to-methylene migration to give the observed product. Ethoxy aryl ethers, including ethoxybenzene, also undergo C-O bond cleavage by (PCP)Ir, but the net reaction in this case is 1,2-elimination of ArO-H to give (PCP)Ir(H)(OAr) and ethylene. DFT calculations point to a low-barrier pathway for this reaction that proceeds through C-H addition of the ethoxy methyl group followed by beta-aryl oxide elimination and loss of ethylene. Thus, both of these distinct C-O cleavage reactions proceed via initial addition of a C(sp(3))-H bond, despite the fact that such bonds are typically considered inert and are much stronger than C-O bonds.

Improving the Accuracy of Laplacian Estimation with Novel Variable Inter-Ring Distances Concentric Ring Electrodes

Directory of Open Access Journals (Sweden)

Oleksandr Makeyev

2016-06-01

Full Text Available Noninvasive concentric ring electrodes are a promising alternative to conventional disc electrodes. Currently, the superiority of tripolar concentric ring electrodes over disc electrodes, in particular, in accuracy of Laplacian estimation, has been demonstrated in a range of applications. In our recent work, we have shown that accuracy of Laplacian estimation can be improved with multipolar concentric ring electrodes using a general approach to estimation of the Laplacian for an (n + 1-polar electrode with n rings using the (4n + 1-point method for n ≥ 2. This paper takes the next step toward further improving the Laplacian estimate by proposing novel variable inter-ring distances concentric ring electrodes. Derived using a modified (4n + 1-point method, linearly increasing and decreasing inter-ring distances tripolar (n = 2 and quadripolar (n = 3 electrode configurations are compared to their constant inter-ring distances counterparts. Finite element method modeling and analytic results are consistent and suggest that increasing inter-ring distances electrode configurations may decrease the truncation error resulting in more accurate Laplacian estimates compared to respective constant inter-ring distances configurations. For currently used tripolar electrode configuration, the truncation error may be decreased more than two-fold, while for the quadripolar configuration more than a six-fold decrease is expected.

Improving the Accuracy of Laplacian Estimation with Novel Variable Inter-Ring Distances Concentric Ring Electrodes

Science.gov (United States)

Makeyev, Oleksandr; Besio, Walter G.

2016-01-01

Noninvasive concentric ring electrodes are a promising alternative to conventional disc electrodes. Currently, the superiority of tripolar concentric ring electrodes over disc electrodes, in particular, in accuracy of Laplacian estimation, has been demonstrated in a range of applications. In our recent work, we have shown that accuracy of Laplacian estimation can be improved with multipolar concentric ring electrodes using a general approach to estimation of the Laplacian for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method for n ≥ 2. This paper takes the next step toward further improving the Laplacian estimate by proposing novel variable inter-ring distances concentric ring electrodes. Derived using a modified (4n + 1)-point method, linearly increasing and decreasing inter-ring distances tripolar (n = 2) and quadripolar (n = 3) electrode configurations are compared to their constant inter-ring distances counterparts. Finite element method modeling and analytic results are consistent and suggest that increasing inter-ring distances electrode configurations may decrease the truncation error resulting in more accurate Laplacian estimates compared to respective constant inter-ring distances configurations. For currently used tripolar electrode configuration, the truncation error may be decreased more than two-fold, while for the quadripolar configuration more than a six-fold decrease is expected. PMID:27294933

Coupled adaptations affecting cleavage of the VP1/2A junction by 3C protease in foot-and-mouth disease virus infected cells

DEFF Research Database (Denmark)

Gullberg, Maria; Polacek, Charlotta; Belsham, Graham

The foot-and-mouth disease virus (FMDV) capsid protein precursor P1-2A is cleaved by the 3C protease to produce VP0, VP3, VP1 and 2A. It was shown previously that modification of a single amino acid residue (K210) within the VP1 protein, close to the VP1/2A cleavage site, inhibited cleavage......, introduction of the 2A L2P substitution alone, or with the VP1 K210E change, into this virus resulted in the production of viable viruses. Cells infected with viruses containing the VP1 K210E and/or the 2A L2P substitutions contained the uncleaved VP1-2A protein; the 2A L2P substitution rendered the VP1/2A...... of this junction and resulted in the production of “self-tagged” virus particles containing the 2A peptide. A second site substitution (E83K) within VP1 was also observed within the rescued virus (Gullberg et al., 2013). It is now shown that introduction of this E83K change alone into a serotype O virus resulted...

Identification of the Products of Oxidation of Quercetin by Air Oxygenat Ambient Temperature

Directory of Open Access Journals (Sweden)

Viktor A Utsal

2007-03-01

Full Text Available Oxidation of quercetin by air oxygen takes place in water and aqueous ethanol solutions under mild conditions, namely in moderately-basic media (pH ∼ 8-10 at ambient temperature and in the absence of any radical initiators, without enzymatic catalysis or irradiation of the reaction media by light. The principal reaction products are typical of other oxidative degradation processes of quercetin, namely 3,4-dihydroxy-benzoic (proto-catechuic and 2,4,6-trihydroxybenzoic (phloroglucinic acids, as well as the decarboxylation product of the latter – 1,3,5-trihydroxybenzene (phloroglucinol. In accordance with the literature data, this process involves the cleavage of the γ-pyrone fragment (ring C of the quercetin molecule by oxygen, with primary formation of 4,6-dihydroxy-2-(3,4-dihydroxybenzoyloxybenzoic acid (depside. However under such mild conditions the accepted mechanism of this reaction (oxidative decarbonylation with formation of carbon monoxide, CO should be reconsidered as preferably an oxidative decarboxylation with formation of carbon dioxide, CO2. Direct head-space analysis of the gaseous components formed during quercetin oxidation in aqueous solution at ambient temperature indicates that the ratio of carbon dioxide/carbon monoxide in the gas phase after acidification of the reaction media is ca. 96:4 %. Oxidation under these mild conditions is typical for other flavonols having OH groups at C3 (e.g., kaempferol, but it is completely suppressed if this hydroxyl group is substituted by a glycoside fragment (as in rutin, or a methyl substituent. An alternative oxidation mechanism involving the direct cleavage of the C2-C3 bond in the diketo-tautomer of quercetin is proposed.

Rapid Removal of Tetrabromobisphenol A by Ozonation in Water: Oxidation Products, Reaction Pathways and Toxicity Assessment.

Directory of Open Access Journals (Sweden)

Ruijuan Qu

Full Text Available Tetrabromobisphenol A (TBBPA is one of the most widely used brominated flame retardants and has attracted more and more attention. In this work, the parent TBBPA with an initial concentration of 100 mg/L was completely removed after 6 min of ozonation at pH 8.0, and alkaline conditions favored a more rapid removal than acidic and neutral conditions. The presence of typical anions and humic acid did not significantly affect the degradation of TBBPA. The quenching test using isopropanol indicated that direct ozone oxidation played a dominant role during this process. Seventeen reaction intermediates and products were identified using an electrospray time-of-flight mass spectrometer. Notably, the generation of 2,4,6-tribromophenol was first observed in the degradation process of TBBPA. The evolution of reaction products showed that ozonation is an efficient treatment for removal of both TBBPA and intermediates. Sequential transformation of organic bromine to bromide and bromate was confirmed by ion chromatography analysis. Two primary reaction pathways that involve cleavage of central carbon atom and benzene ring cleavage concomitant with debromination were thus proposed and further justified by calculations of frontier electron densities. Furthermore, the total organic carbon data suggested a low mineralization rate, even after the complete removal of TBBPA. Meanwhile, the acute aqueous toxicity of reaction solutions to Photobacterium Phosphoreum and Daphnia magna was rapidly decreased during ozonation. In addition, no obvious difference in the attenuation of TBBPA was found by ozone oxidation using different water matrices, and the effectiveness in natural waters further demonstrates that ozonation can be adopted as a promising technique to treat TBBPA-contaminated waters.

Rapid Removal of Tetrabromobisphenol A by Ozonation in Water: Oxidation Products, Reaction Pathways and Toxicity Assessment

Science.gov (United States)

Wang, Xinghao; Huang, Qingguo; Lu, Junhe; Wang, Liansheng; Wang, Zunyao

2015-01-01

Tetrabromobisphenol A (TBBPA) is one of the most widely used brominated flame retardants and has attracted more and more attention. In this work, the parent TBBPA with an initial concentration of 100 mg/L was completely removed after 6 min of ozonation at pH 8.0, and alkaline conditions favored a more rapid removal than acidic and neutral conditions. The presence of typical anions and humic acid did not significantly affect the degradation of TBBPA. The quenching test using isopropanol indicated that direct ozone oxidation played a dominant role during this process. Seventeen reaction intermediates and products were identified using an electrospray time-of-flight mass spectrometer. Notably, the generation of 2,4,6-tribromophenol was first observed in the degradation process of TBBPA. The evolution of reaction products showed that ozonation is an efficient treatment for removal of both TBBPA and intermediates. Sequential transformation of organic bromine to bromide and bromate was confirmed by ion chromatography analysis. Two primary reaction pathways that involve cleavage of central carbon atom and benzene ring cleavage concomitant with debromination were thus proposed and further justified by calculations of frontier electron densities. Furthermore, the total organic carbon data suggested a low mineralization rate, even after the complete removal of TBBPA. Meanwhile, the acute aqueous toxicity of reaction solutions to Photobacterium Phosphoreum and Daphnia magna was rapidly decreased during ozonation. In addition, no obvious difference in the attenuation of TBBPA was found by ozone oxidation using different water matrices, and the effectiveness in natural waters further demonstrates that ozonation can be adopted as a promising technique to treat TBBPA-contaminated waters. PMID:26430733

Radar imaging of Saturn's rings

Science.gov (United States)

Nicholson, Philip D.; French, Richard G.; Campbell, Donald B.; Margot, Jean-Luc; Nolan, Michael C.; Black, Gregory J.; Salo, Heikki J.

2005-09-01

We present delay-Doppler images of Saturn's rings based on radar observations made at Arecibo Observatory between 1999 and 2003, at a wavelength of 12.6 cm and at ring opening angles of 20.1°⩽|B|⩽26.7°. The average radar cross-section of the A ring is ˜77% relative to that of the B ring, while a stringent upper limit of 3% is placed on the cross-section of the C ring and 9% on that of the Cassini Division. These results are consistent with those obtained by Ostro et al. [1982, Icarus 49, 367-381] from radar observations at |B|=21.4°, but provide higher resolution maps of the rings' reflectivity profile. The average cross-section of the A and B rings, normalized by their projected unblocked area, is found to have decreased from 1.25±0.31 to 0.74±0.19 as the rings have opened up, while the circular polarization ratio has increased from 0.64±0.06 to 0.77±0.06. The steep decrease in cross-section is at variance with previous radar measurements [Ostro et al., 1980, Icarus 41, 381-388], and neither this nor the polarization variations are easily understood within the framework of either classical, many-particle-thick or monolayer ring models. One possible explanation involves vertical size segregation in the rings, whereby observations at larger elevation angles which see deeper into the rings preferentially see the larger particles concentrated near the rings' mid-plane. These larger particles may be less reflective and/or rougher and thus more depolarizing than the smaller ones. Images from all four years show a strong m=2 azimuthal asymmetry in the reflectivity of the A ring, with an amplitude of ±20% and minima at longitudes of 67±4° and 247±4° from the sub-Earth point. We attribute the asymmetry to the presence of gravitational wakes in the A ring as invoked by Colombo et al. [1976, Nature 264, 344-345] to explain the similar asymmetry long seen at optical wavelengths. A simple radiative transfer model suggests that the enhancement of the azimuthal

Study of improvement in 1st ring`s gas-seal; Top ring no gas seal seino kojo no kento

Energy Technology Data Exchange (ETDEWEB)

Ando, H; Tateishi, Y; Fujimura, K; Hitosugi, H [Nippon Piston Ring Co. Ltd., Tokyo (Japan)

1997-10-01

The authors studied the effect of an angle of 1st ring twist on the amount of blow-by concerning higher speed/higher output engines for motorcycles. As a result, the authors found the twist made the ring restrained in a ring groove of piston , and confirmed its suitable range for blow-by. By means of the developed optimization method, the authors have achieved significant reduction in blow-by at high engine speed. 1 ref., 9 figs., 2 tabs.

The Poincaré series of a local Gorenstein ring of multiplicity up to 10 ...

Indian Academy of Sciences (India)

As a by-product we prove the rationality of PR for all local, Gorenstein rings of multiplicity at most ..... Due to the choice of α4,...,αn we have. ∑n i=4 αiβi,j ∈ M. Thus aaj ..... [Ma] Matsumura H, Commutative ring theory (Univ. Press: Cambridge) ...

Structural and functional basis for RNA cleavage by Ire1

Directory of Open Access Journals (Sweden)

Stroud Robert M

2011-07-01

Full Text Available Abstract Background The unfolded protein response (UPR controls the protein folding capacity of the endoplasmic reticulum (ER. Central to this signaling pathway is the ER-resident bifunctional transmembrane kinase/endoribonuclease Ire1. The endoribonuclease (RNase domain of Ire1 initiates a non-conventional mRNA splicing reaction, leading to the production of a transcription factor that controls UPR target genes. The mRNA splicing reaction is an obligatory step of Ire1 signaling, yet its mechanism has remained poorly understood due to the absence of substrate-bound crystal structures of Ire1, the lack of structural similarity between Ire1 and other RNases, and a scarcity of quantitative enzymological data. Here, we experimentally define the active site of Ire1 RNase and quantitatively evaluate the contribution of the key active site residues to catalysis. Results This analysis and two new crystal structures suggest that Ire1 RNase uses histidine H1061 and tyrosine Y1043 as the general acid-general base pair contributing ≥ 7.6 kcal/mol and 1.4 kcal/mol to transition state stabilization, respectively, and asparagine N1057 and arginine R1056 for coordination of the scissile phosphate. Investigation of the stem-loop recognition revealed that additionally to the stem-loops derived from the classic Ire1 substrates HAC1 and Xbp1 mRNA, Ire1 can site-specifically and rapidly cleave anticodon stem-loop (ASL of unmodified tRNAPhe, extending known substrate specificity of Ire1 RNase. Conclusions Our data define the catalytic center of Ire1 RNase and suggest a mechanism of RNA cleavage: each RNase monomer apparently contains a separate catalytic apparatus for RNA cleavage, whereas two RNase subunits contribute to RNA stem-loop docking. Conservation of the key residues among Ire1 homologues suggests that the mechanism elucidated here for yeast Ire1 applies to Ire1 in metazoan cells, and to the only known Ire1 homologue RNase L.

The dimer interfaces of protease and extra-protease domains influence the activation of protease and the specificity of GagPol cleavage.

Science.gov (United States)

Pettit, Steven C; Gulnik, Sergei; Everitt, Lori; Kaplan, Andrew H

2003-01-01

Activation of the human immunodeficiency virus type 1 (HIV-1) protease is an essential step in viral replication. As is the case for all retroviral proteases, enzyme activation requires the formation of protease homodimers. However, little is known about the mechanisms by which retroviral proteases become active within their precursors. Using an in vitro expression system, we have examined the determinants of activation efficiency and the order of cleavage site processing for the protease of HIV-1 within the full-length GagPol precursor. Following activation, initial cleavage occurs between the viral p2 and nucleocapsid proteins. This is followed by cleavage of a novel site located in the transframe domain. Mutational analysis of the dimer interface of the protease produced differential effects on activation and specificity. A subset of mutations produced enhanced cleavage at the amino terminus of the protease, suggesting that, in the wild-type precursor, cleavages that liberate the protease are a relatively late event. Replacement of the proline residue at position 1 of the protease dimer interface resulted in altered cleavage of distal sites and suggests that this residue functions as a cis-directed specificity determinant. In summary, our studies indicate that interactions within the protease dimer interface help determine the order of precursor cleavage and contribute to the formation of extended-protease intermediates. Assembly domains within GagPol outside the protease domain also influence enzyme activation.

Magnet design for a low-emittance storage ring

International Nuclear Information System (INIS)

Johansson, Martin; Anderberg, Bengt; Lindgren, Lars-Johan

2014-01-01

The magnet design of the MAX IV 3 GeV storage ring replaces the conventional support girder + discrete magnets scheme of previous third-generation light sources with a compact integrated design having several consecutive magnet elements precision-machined out of a common solid iron block. The MAX IV 3 GeV storage ring, currently under construction, pursues the goal of low electron beam emittance by using a multi-bend achromat magnet lattice, which is realised by having several consecutive magnet elements precision-machined out of a common solid iron block, 2.3–3.4 m long. With this magnet design solution, instead of having 1320 individual magnets, the MAX IV 3 GeV storage ring is built up using 140 integrated ‘magnet block’ units, containing all these magnet elements. Major features of this magnet block design are compactness, vibration stability and that the alignment of magnet elements within each unit is given by the mechanical accuracy of the CNC machining rather than individual field measurement and adjustment. This article presents practical engineering details of implementing this magnet design solution, and mechanical + magnetic field measurement results from the magnet production series. At the time of writing (spring 2014), the production series, which is totally outsourced to industry, is roughly half way through, with mechanical/magnetic QA conforming to specifications. It is the conclusion of the authors that the MAX IV magnet block concept, which has sometimes been described as new or innovative, is from a manufacturing point of view simply a collection of known mature production methods and measurement procedures, which can be executed at fixed cost with a low level of risk

Viscosity of ring polymer melts

KAUST Repository

Pasquino, Rossana

2013-10-15

We have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes, and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts η0,linear to their ring counterparts η0,ring at isofrictional conditions is discussed as a function of the number of entanglements Z. In the unentangled regime η0,linear/η 0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation η0,linear/ η0,ring = 2. In the entanglement regime, the Z-dependence of ring viscosity is much weaker than that of linear polymers, in qualitative agreement with predictions from scaling theory and simulations. The power-law extracted from the available experimental data in the rather limited range 1 < Z < 20, η0,linear/η0,ring ∼ Z 1.2±0.3, is weaker than the scaling prediction (η0,linear/η0,ring ∼ Z 1.6±0.3) and the simulations (η0,linear/ η0,ring ∼ Z2.0±0.3). Nevertheless, the present collection of state-of-the-art experimental data unambiguously demonstrates that rings exhibit a universal trend clearly departing from that of their linear counterparts, and hence it represents a major step toward resolving a 30-year-old problem. © 2013 American Chemical Society.

Viscosity of ring polymer melts

KAUST Repository

Pasquino, Rossana; Vasilakopoulos, Thodoris C.; Jeong, Youncheol; Lee, Hyojoon; Rogers, Simon A.; Sakellariou, Georgios; Allgaier, Jü rgen B.; Takano, Atsushi; Brá s, Ana Rita E; Chang, Taihyun; Gooß en, Sebastian; Pyckhout-Hintzen, Wim; Wischnewski, Andreas; Hadjichristidis, Nikolaos; Richter, Dieter R.; Rubinstein, Michael H.; Vlassopoulos, Dimitris

2013-01-01

We have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes, and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts η0,linear to their ring counterparts η0,ring at isofrictional conditions is discussed as a function of the number of entanglements Z. In the unentangled regime η0,linear/η 0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation η0,linear/ η0,ring = 2. In the entanglement regime, the Z-dependence of ring viscosity is much weaker than that of linear polymers, in qualitative agreement with predictions from scaling theory and simulations. The power-law extracted from the available experimental data in the rather limited range 1 < Z < 20, η0,linear/η0,ring ∼ Z 1.2±0.3, is weaker than the scaling prediction (η0,linear/η0,ring ∼ Z 1.6±0.3) and the simulations (η0,linear/ η0,ring ∼ Z2.0±0.3). Nevertheless, the present collection of state-of-the-art experimental data unambiguously demonstrates that rings exhibit a universal trend clearly departing from that of their linear counterparts, and hence it represents a major step toward resolving a 30-year-old problem. © 2013 American Chemical Society.

Læring og refleksion

DEFF Research Database (Denmark)

Wahlgren, B.; Rattleff, Pernille; Høyrup, S.

State of the art inden for forskning om læring på arbejdspladsen samt gennemgang af læringsteori og refleksionsbegrebet hos Dewey, Dreyfus, Schön, Argyris, Kolb, Jarvis, Mezirow og Brookfield. Afsluttes med diskussion af syntetiseret model for læring på arbejdspladsen.......State of the art inden for forskning om læring på arbejdspladsen samt gennemgang af læringsteori og refleksionsbegrebet hos Dewey, Dreyfus, Schön, Argyris, Kolb, Jarvis, Mezirow og Brookfield. Afsluttes med diskussion af syntetiseret model for læring på arbejdspladsen....

Birth Control Ring

Science.gov (United States)

... Health Food & Fitness Diseases & Conditions Infections Drugs & Alcohol School & Jobs Sports Expert Answers (Q&A) Staying Safe Videos for Educators Search English Español Birth Control Ring KidsHealth / For Teens / Birth Control Ring What's ...

Can laccases catalyze bond cleavage in lignin?

DEFF Research Database (Denmark)

Munk, Line; Sitarz, Anna Katarzyna; Kalyani, Dayanand

2015-01-01

illustrations of the putative laccase catalyzed reactions, including the possible reactions of the reactive radical intermediates taking place after the initial oxidation of the phenol-hydroxyl groups, we show that i) Laccase activity is able to catalyze bond cleavage in low molecular weight phenolic lignin......-substituted phenols, benzenethiols, polyphenols, and polyamines, which may be oxidized. In addition, the currently available analytical methods that can be used to detect enzyme catalyzed changes in lignin are summarized, and an improved nomenclature for unequivocal interpretation of the action of laccases on lignin...

Preventing cleavage of Mer promotes efferocytosis and suppresses acute lung injury in bleomycin treated mice

International Nuclear Information System (INIS)

Lee, Ye-Ji; Lee, Seung-Hae; Youn, Young-So; Choi, Ji-Yeon; Song, Keung-Sub; Cho, Min-Sun; Kang, Jihee Lee

2012-01-01

Mer receptor tyrosine kinase (Mer) regulates macrophage activation and promotes apoptotic cell clearance. Mer activation is regulated through proteolytic cleavage of the extracellular domain. To determine if membrane-bound Mer is cleaved during bleomycin-induced lung injury, and, if so, how preventing the cleavage of Mer enhances apoptotic cell uptake and down-regulates pulmonary immune responses. During bleomycin-induced acute lung injury in mice, membrane-bound Mer expression decreased, but production of soluble Mer and activity as well as expression of disintegrin and metalloproteinase 17 (ADAM17) were enhanced . Treatment with the ADAM inhibitor TAPI-0 restored Mer expression and diminished soluble Mer production. Furthermore, TAPI-0 increased Mer activation in alveolar macrophages and lung tissue resulting in enhanced apoptotic cell clearance in vivo and ex vivo by alveolar macrophages. Suppression of bleomycin-induced pro-inflammatory mediators, but enhancement of hepatocyte growth factor induction were seen after TAPI-0 treatment. Additional bleomycin-induced inflammatory responses reduced by TAPI-0 treatment included inflammatory cell recruitment into the lungs, levels of total protein and lactate dehydrogenase activity in bronchoalveolar lavage fluid, as well as caspase-3 and caspase-9 activity and alveolar epithelial cell apoptosis in lung tissue. Importantly, the effects of TAPI-0 on bleomycin-induced inflammation and apoptosis were reversed by coadministration of specific Mer-neutralizing antibodies. These findings suggest that restored membrane-bound Mer expression by TAPI-0 treatment may help resolve lung inflammation and apoptosis after bleomycin treatment. -- Highlights: ►Mer expression is restored by TAPI-0 treatment in bleomycin-stimulated lung. ►Mer signaling is enhanced by TAPI-0 treatment in bleomycin-stimulated lung. ►TAPI-0 enhances efferocytosis and promotes resolution of lung injury.

Effects of mutations in the VP2/VP4 cleavage site of Swine vesicular disease virus on RNA encapsidation and viral infectivity

NARCIS (Netherlands)

Rebel, J.M.J.; Leendertse, C.H.; Dekker, A.; Moormann, R.J.M.

2003-01-01

We studied VP0 cleavage of Swine vesicular disease virus (SVDV), a member of the Picornaviridae using a full-length cDNA copy of the Dutch SVDV isolate. The influences of mutations, introduced at the cleavage site of SVDV, on VP0 cleavage, RNA encapsidation and viral infection were studied. Double

From coffee ring to spherulites ring of poly(ethylene oxide) film from drying droplet

Science.gov (United States)

Hu, Yinchun; Zhang, Xuerong; Qiu, Maibo; Wei, Yan; Zhou, Qiong; Huang, Di

2018-03-01

We discuss how the "spherulites ring" morphology and "coffee ring" profile of PEO film formed by the drying droplet at glass substrate with different heating rate. Upon increasing the heating rate of substrate, it is found that deposited PEO film from drying droplet shows the unusually observed "coffee ring" profile and "spherulites ring" morphology. The main mechanism for this phenomenon is proposed to be an enhanced Marangoni convection which is induced by the increased solute concentration gradient and reduced viscous force above 70 °C. A simple formation mechanism of the unusually observed "coffee ring" profile and "spherulites ring" morphology is proposed. These findings can be exploited to trace the center of Marangoni convection, with potential applications in designing the spherulite patterns of crystalline polymer films in ink-jet printing and self-assembly fields.

Systematic Search for Rings around Kepler Planet Candidates: Constraints on Ring Size and Occurrence Rate

Science.gov (United States)

Aizawa, Masataka; Masuda, Kento; Kawahara, Hajime; Suto, Yasushi

2018-05-01

We perform a systematic search for rings around 168 Kepler planet candidates with sufficient signal-to-noise ratios that are selected from all of the short-cadence data. We fit ringed and ringless models to their light curves and compare the fitting results to search for the signatures of planetary rings. First, we identify 29 tentative systems, for which the ringed models exhibit statistically significant improvement over the ringless models. The light curves of those systems are individually examined, but we are not able to identify any candidate that indicates evidence for rings. In turn, we find several mechanisms of false positives that would produce ringlike signals, and the null detection enables us to place upper limits on the size of the rings. Furthermore, assuming the tidal alignment between axes of the planetary rings and orbits, we conclude that the occurrence rate of rings larger than twice the planetary radius is less than 15%. Even though the majority of our targets are short-period planets, our null detection provides statistical and quantitative constraints on largely uncertain theoretical models of the origin, formation, and evolution of planetary rings.

Proteolytic cleavage orchestrates cofactor insertion and protein assembly in [NiFe]-hydrogenase biosynthesis.

Science.gov (United States)

Senger, Moritz; Stripp, Sven T; Soboh, Basem

2017-07-14

Metalloenzymes catalyze complex and essential processes, such as photosynthesis, respiration, and nitrogen fixation. For example, bacteria and archaea use [NiFe]-hydrogenases to catalyze the uptake and release of molecular hydrogen (H 2 ). [NiFe]-hydrogenases are redox enzymes composed of a large subunit that harbors a NiFe(CN) 2 CO metallo-center and a small subunit with three iron-sulfur clusters. The large subunit is synthesized with a C-terminal extension, cleaved off by a specific endopeptidase during maturation. The exact role of the C-terminal extension has remained elusive; however, cleavage takes place exclusively after assembly of the [NiFe]-cofactor and before large and small subunits form the catalytically active heterodimer. To unravel the functional role of the C-terminal extension, we used an enzymatic in vitro maturation assay that allows synthesizing functional [NiFe]-hydrogenase-2 of Escherichia coli from purified components. The maturation process included formation and insertion of the NiFe(CN) 2 CO cofactor into the large subunit, endoproteolytic cleavage of the C-terminal extension, and dimerization with the small subunit. Biochemical and spectroscopic analysis indicated that the C-terminal extension of the large subunit is essential for recognition by the maturation machinery. Only upon completion of cofactor insertion was removal of the C-terminal extension observed. Our results indicate that endoproteolytic cleavage is a central checkpoint in the maturation process. Here, cleavage temporally orchestrates cofactor insertion and protein assembly and ensures that only cofactor-containing protein can continue along the assembly line toward functional [NiFe]-hydrogenase. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Electron density enhancement in a quasi isochronous storage ring

International Nuclear Information System (INIS)

Pellegrini, C.; Robin, D.

1991-01-01

The six dimensional phase-space density of an electron beam in a storage ring is determined by the emission of synchrotron radiation, and by the transverse and longitudinal focusing forces determining the particle trajectories. In the simplest case of uncoupled horizontal, vertical and longitudinal motion, the phase space volume occupied by the beam can be characterized by the product of its three projections on the single degree of freedom planes, the horizontal, vertical, and longitudinal emittances. To minimize the beam phase space volume the authors can minimize the transverse and longitudinal emittances. In the case of transverse emittances this problem is very important for synchrotron radiation sources, and has been studied by several authors. A method to minimize the longitudinal emittance, and produce electron bunches with a short pulse length, small energy spread and large peak current has been proposed and discussed recently by C. Pellegrini and D. Robin. This method uses a ring in which the revolution period is weakly dependent on the particle energy, Quasi Isochronous Ring (QIR), in other words a ring with a momentum compaction nearly zero. In this paper they will extend the previous analysis of the conditions for stable single particle motion in such a ring, and give simple criteria for the estimate of the energy spread and phase acceptance of a QIR

On the mechanism of action of ribonucleases: dinucleotide cleavage catalyzed by imidazole and Zn2+.

OpenAIRE

Breslow, R; Huang, D L; Anslyn, E

1989-01-01

Cyclization/cleavage of the 2-(p-nitrophenyl) phosphate ester of propylene glycol is catalyzed by imidazole and, much more effectively, by Zn2+ with imidazole. In the latter case, the mechanism involves simultaneous Lewis acid/base catalysis. Similar Zn2+ and imidazole catalysis of cyclization/cleavage is seen with the dinucleotide 3',5'-UpU (uridylyluridine). Again, the zinc system is much more effective than is catalysis by imidazole alone, and in this case simultaneous Lewis acid/base cata...

Model calibration and beam control systems for storage rings

International Nuclear Information System (INIS)

Corbett, W.J.; Lee, M.J.; Ziemann, V.

1993-04-01

Electron beam storage rings and linear accelerators are rapidly gaining worldwide popularity as scientific devices for the production of high-brightness synchrotron radiation. Today, everybody agrees that there is a premium on calibrating the storage ring model and determining errors in the machine as soon as possible after the beam is injected. In addition, the accurate optics model enables machine operators to predictably adjust key performance parameters, and allows reliable identification of new errors that occur during operation of the machine. Since the need for model calibration and beam control systems is common to all storage rings, software packages should be made that are portable between different machines. In this paper, we report on work directed toward achieving in-situ calibration of the optics model, detection of alignment errors, and orbit control techniques, with an emphasis on developing a portable system incorporating these tools

Force-Induced Calpain Cleavage of Talin Is Critical for Growth, Adhesion Development, and Rigidity Sensing.

Science.gov (United States)

Saxena, Mayur; Changede, Rishita; Hone, James; Wolfenson, Haguy; Sheetz, Michael P

2017-12-13

Cell growth depends upon formation of cell-matrix adhesions, but mechanisms detailing the transmission of signals from adhesions to control proliferation are still lacking. Here, we find that the scaffold protein talin undergoes force-induced cleavage in early adhesions to produce the talin rod fragment that is needed for cell cycle progression. Expression of noncleavable talin blocks cell growth, adhesion maturation, proper mechanosensing, and the related property of EGF activation of motility. Further, the expression of talin rod in the presence of noncleavable full-length talin rescues cell growth and other functions. The cleavage of talin is found in early adhesions where there is also rapid turnover of talin that depends upon calpain and TRPM4 activity as well as the generation of force on talin. Thus, we suggest that an important function of talin is its control over cell cycle progression through its cleavage in early adhesions.

Competitive and Cooperative Torquoselectivity in the thermal ring ...

Indian Academy of Sciences (India)

All the stationary points and TSs were optimized at. B3LYP23/6-31G (d) level using Gaussian 98 software.24. The stationary geometries of reactants and products were characterized with real frequencies and TSs have one imaginary frequency with animation corresponding to conrotatory ring opening. Thermochemical and ...

A Subset of Membrane-Altering Agents and γ-Secretase Modulators Provoke Nonsubstrate Cleavage by Rhomboid Proteases

Directory of Open Access Journals (Sweden)

Siniša Urban

2014-09-01

Full Text Available Rhomboid proteases are integral membrane enzymes that regulate cell signaling, adhesion, and organelle homeostasis pathways, making substrate specificity a key feature of their function. Interestingly, we found that perturbing the membrane pharmacologically in living cells had little effect on substrate processing but induced inappropriate cleavage of nonsubstrates by rhomboid proteases. A subclass of drugs known to modulate γ-secretase activity acted on the membrane directly and induced nonsubstrate cleavage by rhomboid proteases but left true substrate cleavage sites unaltered. These observations highlight an active role for the membrane in guiding rhomboid selectivity and caution that membrane-targeted drugs should be evaluated for cross-activity against membrane-resident enzymes that are otherwise unrelated to the intended drug target. Furthermore, some γ-secretase-modulating activity or toxicity could partly result from global membrane effects.

Structure and dynamics of ringed galaxies

International Nuclear Information System (INIS)

Buta, R.J.

1984-01-01

In many spiral and SO galaxies, single or multiple ring structures are visible in the disk. These inner rings (r), outer rings (R), and nuclear rings (nr) were investigated by means of morphology, photometry, and spectroscopy in order to provide basic data on a long neglected phenomenon. The metric properties of each ring are investigated and found to correlate with the structure of the parent galaxy. When properly calibrated, inner rings in barred (SB) systems can be used as geometric extragalactic distance indicators to distances in excess of 100 Mpc. Other statistics are presented that confirm previous indications that the rings have preferred shapes, relative sizes, and orientations with respect to bars. A survey is made of the less homogeneous non-barred (SA) ringed systems, and the causes of the inhomogeneity are isolated. It is shown that rings can be identified in multiple-ring SA systems that are exactly analogous to those in barred spirals

1,5-Anhydro-D-fructose as Chiral Building Block: A Novel Approach to 1-Deoxymannojirimycin

DEFF Research Database (Denmark)

Maier, Peter; Andersen, Søren Møller; Lundt, Inge

2006-01-01

A novel six-step synthesis of 1-deoxymannojirimycin from 1,5-anhydro-D-fructose in 35% overall yield is reported. The key steps are nucleophilic piperidine ring formation and subsequent Lewis acid induced pyran ether cleavage.......A novel six-step synthesis of 1-deoxymannojirimycin from 1,5-anhydro-D-fructose in 35% overall yield is reported. The key steps are nucleophilic piperidine ring formation and subsequent Lewis acid induced pyran ether cleavage....

DNA cleavage enzymes for treatment of persistent viral infections: Recent advances and the pathway forward

Energy Technology Data Exchange (ETDEWEB)

Weber, Nicholas D., E-mail: nweber@fhcrc.org [Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, E5-110, Seattle, WA 98109 (United States); Department of Laboratory Medicine, University of Washington, Seattle, WA 98195 (United States); Aubert, Martine, E-mail: maubert@fhcrc.org [Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, E5-110, Seattle, WA 98109 (United States); Dang, Chung H., E-mail: cdang@fhcrc.org [Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, E5-110, Seattle, WA 98109 (United States); Stone, Daniel, E-mail: dstone2@fhcrc.org [Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, E5-110, Seattle, WA 98109 (United States); Jerome, Keith R., E-mail: kjerome@fhcrc.org [Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, E5-110, Seattle, WA 98109 (United States); Department of Laboratory Medicine, University of Washington, Seattle, WA 98195 (United States); Department of Microbiology, University of Washington, Seattle, WA 98195 (United States)

2014-04-15

Treatment for most persistent viral infections consists of palliative drug options rather than curative approaches. This is often because long-lasting viral DNA in infected cells is not affected by current antivirals, providing a source for viral persistence and reactivation. Targeting latent viral DNA itself could therefore provide a basis for novel curative strategies. DNA cleavage enzymes can be used to induce targeted mutagenesis of specific genes, including those of exogenous viruses. Although initial in vitro and even in vivo studies have been carried out using DNA cleavage enzymes targeting various viruses, many questions still remain concerning the feasibility of these strategies as they transition into preclinical research. Here, we review the most recent findings on DNA cleavage enzymes for human viral infections, consider the most relevant animal models for several human viral infections, and address issues regarding safety and enzyme delivery. Results from well-designed in vivo studies will ideally provide answers to the most urgent remaining questions, and allow continued progress toward clinical application. - Highlights: • Recent in vitro and in vivo results for DNA cleavage enzymes targeting persistent viral infections. • Analysis of the best animal models for testing enzymes for HBV, HSV, HIV and HPV. • Challenges facing in vivo delivery of therapeutic enzymes for persistent viral infections. • Safety issues to be addressed with proper animal studies.

Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C2-symmetric building block: a strategy for the synthesis of decanolide natural products

Directory of Open Access Journals (Sweden)

Bernd Schmidt

2013-11-01

Full Text Available Starting from the conveniently available ex-chiral pool building block (R,R-hexa-1,5-diene-3,4-diol, the ten-membered ring lactones stagonolide E and curvulide A were synthesized using a bidirectional olefin-metathesis functionalization of the terminal double bonds. Key steps are (i a site-selective cross metathesis, (ii a highly diastereoselective extended tethered RCM to furnish a (Z,E-configured dienyl carboxylic acid and (iii a Ru–lipase-catalyzed dynamic kinetic resolution to establish the desired configuration at C9. Ring closure was accomplished by macrolactonization. Curvulide A was synthesized from stagonolide E through Sharpless epoxidation.

Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C 2-symmetric building block: a strategy for the synthesis of decanolide natural products.

Science.gov (United States)

Schmidt, Bernd; Kunz, Oliver

2013-01-01

Starting from the conveniently available ex-chiral pool building block (R,R)-hexa-1,5-diene-3,4-diol, the ten-membered ring lactones stagonolide E and curvulide A were synthesized using a bidirectional olefin-metathesis functionalization of the terminal double bonds. Key steps are (i) a site-selective cross metathesis, (ii) a highly diastereoselective extended tethered RCM to furnish a (Z,E)-configured dienyl carboxylic acid and (iii) a Ru-lipase-catalyzed dynamic kinetic resolution to establish the desired configuration at C9. Ring closure was accomplished by macrolactonization. Curvulide A was synthesized from stagonolide E through Sharpless epoxidation.

Lie algebras for the Dirac-Clifford ring

International Nuclear Information System (INIS)

Mignaco, J.A.; Linhares, C.A.

1992-01-01

It is shown in a general way that the Dirac-Clifford ring formed by the Dirac matrices and all their products, for all even and odd spacetime dimensions D, span the cumulation algebras SU(2 D/2 ) for even D and SU(2 (D- 1 )/2 ) + SU(2 (D-1)/2 ) for odd D. Some physical consequences of these results are discussed. (author)

RISC-interacting clearing 3’- 5’ exoribonucleases (RICEs) degrade uridylated cleavage fragments to maintain functional RISC in Arabidopsis thaliana

Science.gov (United States)

Zhang, Zhonghui; Hu, Fuqu; Sung, Min Woo; Shu, Chang; Castillo-González, Claudia; Koiwa, Hisashi; Tang, Guiliang; Dickman, Martin; Li, Pingwei; Zhang, Xiuren

2017-01-01

RNA-induced silencing complex (RISC) is composed of miRNAs and AGO proteins. AGOs use miRNAs as guides to slice target mRNAs to produce truncated 5' and 3' RNA fragments. The 5' cleaved RNA fragments are marked with uridylation for degradation. Here, we identified novel cofactors of Arabidopsis AGOs, named RICE1 and RICE2. RICE proteins specifically degraded single-strand (ss) RNAs in vitro; but neither miRNAs nor miRNA*s in vivo. RICE1 exhibited a DnaQ-like exonuclease fold and formed a homohexamer with the active sites located at the interfaces between RICE1 subunits. Notably, ectopic expression of catalytically-inactive RICE1 not only significantly reduced miRNA levels; but also increased 5' cleavage RISC fragments with extended uridine tails. We conclude that RICEs act to degrade uridylated 5’ products of AGO cleavage to maintain functional RISC. Our study also suggests a possible link between decay of cleaved target mRNAs and miRNA stability in RISC. DOI: http://dx.doi.org/10.7554/eLife.24466.001 PMID:28463111

Physiological Responses during Cycling With Oval Chainrings (Q-Ring) and Circular Chainrings.

Science.gov (United States)

Cordova, Alfredo; Latasa, Iban; Seco, Jesus; Villa, Gerardo; Rodriguez-Falces, Javier

2014-05-01

conventional chainrings.During the short sprints performed after the incremental test, there were no statistical differences in power production between oval "Q-rings" and conventional chainrings.

Use of a ring-shaped, passively stable, superconducting magnetic bearing in the ring spinning process; Einsatz eines ringfoermigen, passiv stabilen, supraleitenden Magnetlagers im Ringspinnprozess

Energy Technology Data Exchange (ETDEWEB)

Berger, Anne; Sparing, Maria; Berger, Dietmar; Fuchs, Guenter; Schultz, Ludwig [IFW Dresden (Germany). Inst. fuer Metallische Werkstoffe; Hossain, Mahmud; Abdkader, Anwar; Cherif, Chokri [TU Dresden (Germany). ITM

2015-07-01

For the integration of a superconducting magnetic bearing in a ring spinning machine a LN{sub 2} continuous flow cryostat was developed, which is needed to cool the superconductor below its transition temperature of ∝91 K and simultaneously ensures that the spinning process takes place at room temperature. The ring spinning process is the most widely used process for spinning yarn. In this case, a loose fiber connection is first stretched in a roller system, then twisted by the so-called spinning ring-ring traveler system, and finally wound on a spindle. The spinning ring is a circular guide, which is mounted around the spindle. On this the ring traveler rotates as yarn guide. The yarn is driven by the rotation of the spindle and there is a balloon-shaped movement of the yarn which results the twist. The productivity of the process is limited by the systematic frictional heat between the yarn, spinning ring and ring travelers. This leads at high speeds to yarn breakage and limits the maximum spindle speed depending on the type of fiber to a maximum of 25,000 U/min. To increase the speed and thus the productivity of the process, the conventional spinning ring-ring rotor system is replaced by a superconducting magnetic bearing. Here floats a NdFeB permanent magnet passively stable over the LN{sub 2} cooled ceramic high-temperature superconductor YBa{sub 2}Cu{sub 3}O{sub 7-x}. Driven by the yarn the permanent magnet rotates, thus ensuring the necessary balloon-shaped yarn movement to twist. Such a bearing has been successfully tested in a ring spinning machine. Preliminary results show a similar yarn quality. [German] Fuer die Integration eines supraleitenden Magnetlagers in eine Ringspinnmaschine wurde ein LN{sub 2}-Durchflusskryostat entwickelt, der noetig ist, um den Supraleiter unter seine Sprungtemperatur von ∝91 K zu kuehlen und gleichzeitig dafuer sorgt, dass der Spinnprozess bei Raumtemperatur ablaeuft. Der Ringspinnprozess ist der am weitesten verbreitete

Binomial Rings: Axiomatisation, Transfer and Classification

OpenAIRE

Xantcha, Qimh Richey

2011-01-01

Hall's binomial rings, rings with binomial coefficients, are given an axiomatisation and proved identical to the numerical rings studied by Ekedahl. The Binomial Transfer Principle is established, enabling combinatorial proofs of algebraical identities. The finitely generated binomial rings are completely classified. An application to modules over binomial rings is given.

AN N-BODY INTEGRATOR FOR GRAVITATING PLANETARY RINGS, AND THE OUTER EDGE OF SATURN'S B RING

International Nuclear Information System (INIS)

Hahn, Joseph M.; Spitale, Joseph N.

2013-01-01

A new symplectic N-body integrator is introduced, one designed to calculate the global 360° evolution of a self-gravitating planetary ring that is in orbit about an oblate planet. This freely available code is called epi i nt, and it is distinct from other such codes in its use of streamlines to calculate the effects of ring self-gravity. The great advantage of this approach is that the perturbing forces arise from smooth wires of ring matter rather than discreet particles, so there is very little gravitational scattering and so only a modest number of particles are needed to simulate, say, the scalloped edge of a resonantly confined ring or the propagation of spiral density waves. The code is applied to the outer edge of Saturn's B ring, and a comparison of Cassini measurements of the ring's forced response to simulations of Mimas's resonant perturbations reveals that the B ring's surface density at its outer edge is σ 0 = 195 ± 60 g cm –2 , which, if the same everywhere across the ring, would mean that the B ring's mass is about 90% of Mimas's mass. Cassini observations show that the B ring-edge has several free normal modes, which are long-lived disturbances of the ring-edge that are not driven by any known satellite resonances. Although the mechanism that excites or sustains these normal modes is unknown, we can plant such a disturbance at a simulated ring's edge and find that these modes persist without any damping for more than ∼10 5 orbits or ∼100 yr despite the simulated ring's viscosity ν s = 100 cm 2 s –1 . These simulations also indicate that impulsive disturbances at a ring can excite long-lived normal modes, which suggests that an impact in the recent past by perhaps a cloud of cometary debris might have excited these disturbances, which are quite common to many of Saturn's sharp-edged rings

Glutamic Acid Selective Chemical Cleavage of Peptide Bonds.

Science.gov (United States)

Nalbone, Joseph M; Lahankar, Neelam; Buissereth, Lyssa; Raj, Monika

2016-03-04

Site-specific hydrolysis of peptide bonds at glutamic acid under neutral aqueous conditions is reported. The method relies on the activation of the backbone amide chain at glutamic acid by the formation of a pyroglutamyl (pGlu) imide moiety. This activation increases the susceptibility of a peptide bond toward hydrolysis. The method is highly specific and demonstrates broad substrate scope including cleavage of various bioactive peptides with unnatural amino acid residues, which are unsuitable substrates for enzymatic hydrolysis.

Galactic rings revisited - I. CVRHS classifications of 3962 ringed galaxies from the Galaxy Zoo 2 Database

Science.gov (United States)

Buta, Ronald J.

2017-11-01

Rings are important and characteristic features of disc-shaped galaxies. This paper is the first in a series that re-visits galactic rings with the goals of further understanding the nature of the features and for examining their role in the secular evolution of galaxy structure. The series begins with a new sample of 3962 galaxies drawn from the Galaxy Zoo 2 citizen science data base, selected because zoo volunteers recognized a ring-shaped pattern in the morphology as seen in Sloan Digital Sky Survey colour images. The galaxies are classified within the framework of the Comprehensive de Vaucouleurs revised Hubble-Sandage system. It is found that zoo volunteers cued on the same kinds of ring-like features that were recognized in the 1995 Catalogue of Southern Ringed Galaxies. This paper presents the full catalogue of morphological classifications, comparisons with other sources of classifications and some histograms designed mainly to highlight the content of the catalogue. The advantages of the sample are its large size and the generally good quality of the images; the main disadvantage is the low physical resolution that limits the detectability of linearly small rings such as nuclear rings. The catalogue includes mainly inner and outer disc rings and lenses. Cataclysmic (`encounter-driven') rings (such as ring and polar ring galaxies) are recognized in less than 1 per cent of the sample.

The Role of G-Protein-Coupled Receptor Proteolysis Site Cleavage of Polycystin-1 in Renal Physiology and Polycystic Kidney Disease

Directory of Open Access Journals (Sweden)

Marie Trudel

2016-01-01

Full Text Available Polycystin-1 (PC1 plays an essential role in renal tubular morphogenesis, and PC1 dysfunction causes human autosomal dominant polycystic kidney disease. A fundamental characteristic of PC1 is post-translational modification via cleavage at the juxtamembrane GPCR proteolysis site (GPS motif that is part of the larger GAIN domain. Given the considerable biochemical complexity of PC1 molecules generated in vivo by this process, GPS cleavage has several profound implications on the intracellular trafficking and localization in association with their particular function. The critical nature of GPS cleavage is further emphasized by the increasing numbers of PKD1 mutations that significantly affect this cleavage process. The GAIN domain with the GPS motif therefore represents the key structural element with fundamental importance for PC1 and might be polycystic kidney disease’s (PKD Achilles’ heel in a large spectrum of PKD1 missense mutations. We highlight the central roles of PC1 cleavage for the regulation of its biogenesis, intracellular trafficking and function, as well as its significance in polycystic kidney disease.

Quantum Fourier Transform Over Galois Rings

OpenAIRE

Zhang, Yong

2009-01-01

Galois rings are regarded as "building blocks" of a finite commutative ring with identity. There have been many papers on classical error correction codes over Galois rings published. As an important warm-up before exploring quantum algorithms and quantum error correction codes over Galois rings, we study the quantum Fourier transform (QFT) over Galois rings and prove it can be efficiently preformed on a quantum computer. The properties of the QFT over Galois rings lead to the quantum algorit...

Novel manifestations of the Aharonov-Bohm effect in quantum rings and Moebius rings

International Nuclear Information System (INIS)

Fomin, Vladimir M.

2013-01-01

- An overview is given on the recent experimental and theoretical advancements in studies of novel manifestations of the Aharonov-Bohm quantum-interference effect for excitons confined to self assembled quantum rings and other semiconductor nanostructures with ring-like states of charge carriers as well as for electrons in Moebius rings at the micro- and nanoscale. The exciton Aharonov-Bohm effect can be effectively controlled by an out-of-plane magnetic field, a vertical electric field, a spin disorder. A 'delocalization-to-localization' transition for the electron ground state occurs in a Moebius ring as it is made more inhomogeneous. (authors)

Ring closure in actin polymers

Energy Technology Data Exchange (ETDEWEB)

Sinha, Supurna, E-mail: supurna@rri.res.in [Raman Research Institute, Bangalore 560080 (India); Chattopadhyay, Sebanti [Doon University, Dehradun 248001 (India)

2017-03-18

We present an analysis for the ring closure probability of semiflexible polymers within the pure bend Worm Like Chain (WLC) model. The ring closure probability predicted from our analysis can be tested against fluorescent actin cyclization experiments. We also discuss the effect of ring closure on bend angle fluctuations in actin polymers. - Highlights: • Ring closure of biopolymers. • Worm like chain model. • Predictions for experiments.

On P-coherent endomorphism rings

Indian Academy of Sciences (India)

A ring is called right -coherent if every principal right ideal is finitely presented. Let M R be a right -module. We study the -coherence of the endomorphism ring of M R . It is shown that is a right -coherent ring if and only if every endomorphism of M R has a pseudokernel in add M R ; S is a left -coherent ring if and ...

Cell elongation is an adaptive response for clearing long chromatid arms from the cleavage plane

Science.gov (United States)

Kotadia, Shaila; Montembault, Emilie; Sullivan, William

2012-01-01

Chromosome segregation must be coordinated with cell cleavage to ensure correct transmission of the genome to daughter cells. Here we identify a novel mechanism by which Drosophila melanogaster neuronal stem cells coordinate sister chromatid segregation with cleavage furrow ingression. Cells adapted to a dramatic increase in chromatid arm length by transiently elongating during anaphase/telophase. The degree of cell elongation correlated with the length of the trailing chromatid arms and was concomitant with a slight increase in spindle length and an enlargement of the zone of cortical myosin distribution. Rho guanine-nucleotide exchange factor (Pebble)–depleted cells failed to elongate during segregation of long chromatids. As a result, Pebble-depleted adult flies exhibited morphological defects likely caused by cell death during development. These studies reveal a novel pathway linking trailing chromatid arms and cortical myosin that ensures the clearance of chromatids from the cleavage plane at the appropriate time during cytokinesis, thus preserving genome integrity. PMID:23185030

Metabolic cleavage of cell-penetrating peptides in contact with epithelial models

DEFF Research Database (Denmark)

Tréhin, Rachel; Nielsen, Hanne Mørck; Jahnke, Heinz-Georg

2004-01-01

We assessed the metabolic degradation kinetics and cleavage patterns of some selected CPP (cell-penetrating peptides) after incubation with confluent epithelial models. Synthesis of N-terminal CF [5(6)-carboxyfluorescein]-labelled CPP, namely hCT (human calcitonin)-derived sequences, Tat(47-57) a...

Optics design of Intrabeam Scattering dominated damping rings

CERN Document Server

Antoniou, Fanouria; Papaphilippou, Ioannis

A e+/e- linear collider, the Compact Linear Collider (CLIC) is under design at CERN, aiming to explore the terascale particle physics regime. The collider has been optimized at 3 TeV center of mass energy and targets a luminosity of 1034 cm-2 s-1. In order to achieve this high luminosity, high intensity bunches with ultra low emittances, in all three planes, are required. The generation of ultra low emittance is achieved in the Damping Rings (DR) complex of the collider. The large input beam emittances, especially the ones coming from the positron source, and the requirement of ultra low emittance production in a fast repetition time of 20 ms, imply that the beam damping is done in two stages. Thus, a main-damping ring (DR) and a predamping ring (PDR) are needed, for each particle species. The high bunch brightness gives rise to several collective effects, with Intra-beam scattering (IBS) being the main limitation to the ultra-low emittance. This thesis elaborates the lattice design and non-linear optimizatio...

Problems and criteria of quality improvement in end face mechanical seal rings through technological methods

Science.gov (United States)

Tarelnik, V.; Belous, A.; Antoszewski, B.; Zukov, A.

2017-08-01

In this paper are presented the recommendations for material’s selections of the mechanical seals rings and basic productive and operating requirements. The system of a directional selection of technology that ensures the required quality of working surfaces of the mechanical seals rings covers their entire life cycle. The mathematical frictional model is proposed as an instrument for calculating a linear and weighing abrasion of the mechanical seals rings and helps to improve selection’s criteria and the most rational method of strengthening.

Faithfully quadratic rings

CERN Document Server

Dickmann, M

2015-01-01

In this monograph the authors extend the classical algebraic theory of quadratic forms over fields to diagonal quadratic forms with invertible entries over broad classes of commutative, unitary rings where -1 is not a sum of squares and 2 is invertible. They accomplish this by: (1) Extending the classical notion of matrix isometry of forms to a suitable notion of T-isometry, where T is a preorder of the given ring, A, or T = A^2. (2) Introducing in this context three axioms expressing simple properties of (value) representation of elements of the ring by quadratic forms, well-known to hold in

Carotenoid Cleavage Oxygenases from Microbes and Photosynthetic Organisms: Features and Functions

Directory of Open Access Journals (Sweden)

Oussama Ahrazem

2016-10-01

Full Text Available Apocarotenoids are carotenoid-derived compounds widespread in all major taxonomic groups, where they play important roles in different physiological processes. In addition, apocarotenoids include compounds with high economic value in food and cosmetics industries. Apocarotenoid biosynthesis starts with the action of carotenoid cleavage dioxygenases (CCDs, a family of non-heme iron enzymes that catalyze the oxidative cleavage of carbon–carbon double bonds in carotenoid backbones through a similar molecular mechanism, generating aldehyde or ketone groups in the cleaving ends. From the identification of the first CCD enzyme in plants, an increasing number of CCDs have been identified in many other species, including microorganisms, proving to be a ubiquitously distributed and evolutionarily conserved enzymatic family. This review focuses on CCDs from plants, algae, fungi, and bacteria, describing recent progress in their functions and regulatory mechanisms in relation to the different roles played by the apocarotenoids in these organisms.

BERKELEY: ALS ring

Energy Technology Data Exchange (ETDEWEB)

Anon.

1993-06-15

Everybody at Lawrence Berkeley Laboratory's Center for Beam Physics is pleased with the rapid progress in commissioning LBL's Advanced Light Source (ALS) electron storage ring, the foundation for this third-generation synchrotron radiation facility. Designed for a maximum current of 400 mA, the ALS storage ring reached 407 mA just 24 days after storing the first beam on 16 March. ALS construction as a US Department of Energy (DOE) national user facility to provide high-brightness vacuum ultra-violet and soft x-ray radiation began in October 1987. One technical requirement marking project completion was to accumulate a 50-mA current in the storage ring. The ALS passed this milestone on 24 March, a week ahead of the official deadline. Once injected, the electron beam decays quasi-exponentially primarily because of interactions with residual gas molecules in the storage-ring vacuum chamber. Eventually, when the pressure in the vacuum chamber with beam decreases toward the expected operating level of 1 nano Torr, it will only be necessary to refill the storage ring at intervals of four to eight hours. At present the vacuum is improving rapidly as surfaces are irradiated (scrubbed) by the synchrotron radiation itself. At 100 mA, beam lifetime was about one hour (9 April)

Compressible Vortex Ring

Science.gov (United States)

Elavarasan, Ramasamy; Arakeri, Jayawant; Krothapalli, Anjaneyulu

1999-11-01

The interaction of a high-speed vortex ring with a shock wave is one of the fundamental issues as it is a source of sound in supersonic jets. The complex flow field induced by the vortex alters the propagation of the shock wave greatly. In order to understand the process, a compressible vortex ring is studied in detail using Particle Image Velocimetry (PIV) and shadowgraphic techniques. The high-speed vortex ring is generated from a shock tube and the shock wave, which precedes the vortex, is reflected back by a plate and made to interact with the vortex. The shadowgraph images indicate that the reflected shock front is influenced by the non-uniform flow induced by the vortex and is decelerated while passing through the vortex. It appears that after the interaction the shock is "split" into two. The PIV measurements provided clear picture about the evolution of the vortex at different time interval. The centerline velocity traces show the maximum velocity to be around 350 m/s. The velocity field, unlike in incompressible rings, contains contributions from both the shock and the vortex ring. The velocity distribution across the vortex core, core diameter and circulation are also calculated from the PIV data.

BERKELEY: ALS ring

International Nuclear Information System (INIS)

Anon.

1993-01-01

Everybody at Lawrence Berkeley Laboratory's Center for Beam Physics is pleased with the rapid progress in commissioning LBL's Advanced Light Source (ALS) electron storage ring, the foundation for this third-generation synchrotron radiation facility. Designed for a maximum current of 400 mA, the ALS storage ring reached 407 mA just 24 days after storing the first beam on 16 March. ALS construction as a US Department of Energy (DOE) national user facility to provide high-brightness vacuum ultra-violet and soft x-ray radiation began in October 1987. One technical requirement marking project completion was to accumulate a 50-mA current in the storage ring. The ALS passed this milestone on 24 March, a week ahead of the official deadline. Once injected, the electron beam decays quasi-exponentially primarily because of interactions with residual gas molecules in the storage-ring vacuum chamber. Eventually, when the pressure in the vacuum chamber with beam decreases toward the expected operating level of 1 nano Torr, it will only be necessary to refill the storage ring at intervals of four to eight hours. At present the vacuum is improving rapidly as surfaces are irradiated (scrubbed) by the synchrotron radiation itself. At 100 mA, beam lifetime was about one hour (9 April)

Performance of high-resolution position-sensitive detectors developed for storage-ring decay experiments

International Nuclear Information System (INIS)

Yamaguchi, T.; Suzaki, F.; Izumikawa, T.; Miyazawa, S.; Morimoto, K.; Suzuki, T.; Tokanai, F.; Furuki, H.; Ichihashi, N.; Ichikawa, C.; Kitagawa, A.; Kuboki, T.; Momota, S.; Nagae, D.; Nagashima, M.; Nakamura, Y.; Nishikiori, R.; Niwa, T.; Ohtsubo, T.; Ozawa, A.

2013-01-01

Highlights: • Position-sensitive detectors were developed for storage-ring decay spectroscopy. • Fiber scintillation and silicon strip detectors were tested with heavy ion beams. • A new fiber scintillation detector showed an excellent position resolution. • Position and energy detection by silicon strip detectors enable full identification. -- Abstract: As next generation spectroscopic tools, heavy-ion cooler storage rings will be a unique application of highly charged RI beam experiments. Decay spectroscopy of highly charged rare isotopes provides us important information relevant to the stellar conditions, such as for the s- and r-process nucleosynthesis. In-ring decay products of highly charged RI will be momentum-analyzed and reach a position-sensitive detector set-up located outside of the storage orbit. To realize such in-ring decay experiments, we have developed and tested two types of high-resolution position-sensitive detectors: silicon strips and scintillating fibers. The beam test experiments resulted in excellent position resolutions for both detectors, which will be available for future storage-ring experiments

A study of the production of high -psub(T) π0s at the CERN intersecting storage rings

International Nuclear Information System (INIS)

Kourkoumelis, C.; Resvanis, L.K.; Filippas, T.A.; Fokitis, E.; Cnops, A.M.; Iwata, S.; Palmer, R.B.; Rahm, D.C.; Rehak, P.; Stumer, I.

1980-01-01

The inclusive cross-section for π 0 production near 90 0 in pp collisions at the CERN Intersecting Storage Rings has been studied for the psub(T) range 3 0 → γγ decay were resolved and measured separately for sub(T)u values up to 10 GeV/c. Results indicate an agreement with the psub(T) -8 behaviour for the lower values of psub(T) and a slower decrease of the cross-section for the higher values of psub(T). The high-psub(T) data deviate the scaling expression psub(T)sup(-n)F(kappasub(T)), which holds for the lower psub(T) values (psub(T) < 8 GeV/c). (orig.)

Accidental ingestion of BiTine ring and a note on inefficient ring separation forceps

Directory of Open Access Journals (Sweden)

Baghele ON

2011-05-01

Full Text Available Om Nemichand Baghele1, Mangala Om Baghele21Department of Periodontology, SMBT Dental College and Hospital, Sangamner, Ahmednagar, Maharashtra, India; 2Private General Dental Practice, Mumbai, IndiaBackground: Accidental ingestion of medium-to-large instruments is relatively uncommon during dental treatment but can be potentially dangerous. A case of BiTine ring ingestion is presented with a note on inefficient ring separation forceps.Case description: A 28-year-old male patient accidentally ingested the BiTine ring (2 cm diameter, 0.5 cm outward projections while it was being applied to a distoproximal cavity in tooth # 19. The ring placement forceps were excessively flexible; bending of the beaks towards the ring combined with a poor no-slippage mechanism led to sudden disengagement of the ring and accelerated movement towards the pharynx. We followed the patient with bulk forming agents and radiographs. Fortunately the ring passed out without any complications.Clinical implications: Checking equipment and methods is as important as taking precautions against any preventable medical emergency. It is the responsibility of the clinician to check, verify and then use any instrument/equipment.Keywords: foreign bodies/radiography, foreign bodies/complications, equipment failure, dental instrument, accidental ingestion

Base substitutions at scissile bond sites are sufficient to alter RNA-binding and cleavage activity of RNase III.

Science.gov (United States)

Kim, Kyungsub; Sim, Se-Hoon; Jeon, Che Ok; Lee, Younghoon; Lee, Kangseok

2011-02-01

RNase III, a double-stranded RNA-specific endoribonuclease, degrades bdm mRNA via cleavage at specific sites. To better understand the mechanism of cleavage site selection by RNase III, we performed a genetic screen for sequences containing mutations at the bdm RNA cleavage sites that resulted in altered mRNA stability using a transcriptional bdm'-'cat fusion construct. While most of the isolated mutants showed the increased bdm'-'cat mRNA stability that resulted from the inability of RNase III to cleave the mutated sequences, one mutant sequence (wt-L) displayed in vivo RNA stability similar to that of the wild-type sequence. In vivo and in vitro analyses of the wt-L RNA substrate showed that it was cut only once on the RNA strand to the 5'-terminus by RNase III, while the binding constant of RNase III to this mutant substrate was moderately increased. A base substitution at the uncleaved RNase III cleavage site in wt-L mutant RNA found in another mutant lowered the RNA-binding affinity by 11-fold and abolished the hydrolysis of scissile bonds by RNase III. Our results show that base substitutions at sites forming the scissile bonds are sufficient to alter RNA cleavage as well as the binding activity of RNase III. © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Fate of CL-20 in sandy soils: Degradation products as potential markers of natural attenuation

International Nuclear Information System (INIS)

Monteil-Rivera, Fanny; Halasz, Annamaria; Manno, Dominic; Kuperman, Roman G.; Thiboutot, Sonia; Ampleman, Guy; Hawari, Jalal

2009-01-01

Hexanitrohexaazaisowurtzitane (CL-20) is an emerging explosive that may replace the currently used explosives such as RDX and HMX, but little is known about its fate in soil. The present study was conducted to determine degradation products of CL-20 in two sandy soils under abiotic and biotic anaerobic conditions. Biotic degradation was prevalent in the slightly acidic VT soil, which contained a greater organic C content, while the slightly alkaline SAC soil favored hydrolysis. CL-20 degradation was accompanied by the formation of formate, glyoxal, nitrite, ammonium, and nitrous oxide. Biotic degradation of CL-20 occurred through the formation of its denitrohydrogenated derivative (m/z 393 Da) while hydrolysis occurred through the formation of a ring cleavage product (m/z 156 Da) that was tentatively identified as CH 2 =N-C(=N-NO 2 )-CH=N-CHO or its isomer N(NO 2 )=CH-CH=N-CO-CH=NH. Due to their chemical specificity, these two intermediates may be considered as markers of in situ attenuation of CL-20 in soil. - Two key intermediates of CL-20 degradation are potential markers of its natural attenuation in soil

Snake venom serine proteinases specificity mapping by proteomic identification of cleavage sites.

Science.gov (United States)

Zelanis, André; Huesgen, Pitter F; Oliveira, Ana Karina; Tashima, Alexandre K; Serrano, Solange M T; Overall, Christopher M

2015-01-15

Many snake venom toxins are serine proteases but their specific in vivo targets are mostly unknown. Various act on components of the coagulation cascade, and fibrinolytic and kallikrein-kinin systems to trigger various pathological effects observed in the envenomation. Despite showing high similarity in terms of primary structure snake venom serine proteinases (SVSPs) show exquisite specificity towards macromolecular substrates. Therefore, the characterization of their peptide bond specificity is important for understanding the active site preference associated with effective proteolysis as well as for the design of peptide substrates and inhibitors. Bothrops jararaca contains various SVSPs among which Bothrops protease A is a specific fibrinogenolytic agent and PA-BJ is a platelet-activating enzyme. In this study we used proteome derived peptide libraries in the Proteomic Identification of protease Cleavage Sites (PICS) approach to explore the peptide bond specificity of Bothrops protease A and PA-BJ in order to determine their individual peptide cleavage sequences. A total of 371 cleavage sites (208 for Bothrops protease A and 163 for PA-BJ) were detected and both proteinases displayed a clear preference for arginine at the P1 position. Moreover, the analysis of the specificity profiles of Bothrops protease A and PA-BJ revealed subtle differences in the preferences along P6-P6', despite a common yet unusual preference for Pro at P2. Taken together, these results map the subsite specificity of both SVSPs and shed light in the functional differences between these proteinases. Proteolysis is key to various pathological effects observed upon envenomation by viperid snakes. The use of the Proteomic Identification of protease Cleavage Sites (PICS) approach for the easy mapping of proteinase subsite preferences at both the prime- and non-prime sides concurrently gives rise to a fresh understanding of the interaction of the snake venom serine proteinases with peptide and

On the Laurent polynomial rings

International Nuclear Information System (INIS)

Stefanescu, D.

1985-02-01

We describe some properties of the Laurent polynomial rings in a finite number of indeterminates over a commutative unitary ring. We study some subrings of the Laurent polynomial rings. We finally obtain two cancellation properties. (author)

The Hi-Ring DCN Architecture

DEFF Research Database (Denmark)

Galili, Michael; Kamchevska, Valerija; Ding, Yunhong

2016-01-01

We will review recent work on the proposed hierarchical ring-based architecture (HiRing) proposed for data center networks. We will discuss the architecture and initial demonstrations of optical switching performance and time-domain synchronization......We will review recent work on the proposed hierarchical ring-based architecture (HiRing) proposed for data center networks. We will discuss the architecture and initial demonstrations of optical switching performance and time-domain synchronization...

Myc-nick: a cytoplasmic cleavage product of Myc that promotes alpha-tubulin acetylation and cell differentiation.

Science.gov (United States)

Conacci-Sorrell, Maralice; Ngouenet, Celine; Eisenman, Robert N

2010-08-06

The Myc oncoprotein family comprises transcription factors that control multiple cellular functions and are widely involved in oncogenesis. Here we report the identification of Myc-nick, a cytoplasmic form of Myc generated by calpain-dependent proteolysis at lysine 298 of full-length Myc. Myc-nick retains conserved Myc box regions but lacks nuclear localization signals and the bHLHZ domain essential for heterodimerization with Max and DNA binding. Myc-nick induces alpha-tubulin acetylation and altered cell morphology by recruiting histone acetyltransferase GCN5 to microtubules. During muscle differentiation, while the levels of full-length Myc diminish, Myc-nick and acetylated alpha-tubulin levels are increased. Ectopic expression of Myc-nick accelerates myoblast fusion, triggers the expression of myogenic markers, and permits Myc-deficient fibroblasts to transdifferentiate in response to MyoD. We propose that the cleavage of Myc by calpain abrogates the transcriptional inhibition of differentiation by full-length Myc and generates Myc-nick, a driver of cytoplasmic reorganization and differentiation. Copyright 2010 Elsevier Inc. All rights reserved.

EBT ring physics

International Nuclear Information System (INIS)

Uckan, N.A.

1980-04-01

This workshop attempted to evaluate the status of the current experimental and theoretical understanding of hot electron ring properties. The dominant physical processes that influence ring formation, scaling, and their optimal behavior are also studied. Separate abstracts were prepared for each of the 27 included papers

Monoclonal antibodies to the reactive centre loop (RCL) of human corticosteroid-binding globulin (CBG) can protect against proteolytic cleavage.

Science.gov (United States)