Thermostability of Multidomain Proteins: Elongation Factors EF-Tu from Escherichia coli and Bacillus stearothermophilus and Their Chimeric Forms

Czech Academy of Sciences Publication Activity Database

Šanderová, Hana; Hůlková, Marta; Maloň, Petr; Kepková, M.; Jonák, Jiří

2004-01-01

Roč. 13, č. 1 (2004), s. 89-99 ISSN 0961-8368 R&D Projects: GA AV ČR IPP1050128; GA ČR GA204/98/0863; GA ČR GA303/02/0689 Institutional research plan: CEZ:AV0Z4055905; CEZ:AV0Z5052915 Keywords : elongation factor EF-Tu, thermostability, chimeric protein Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.116, year: 2004

Ubiquitin fusion constructs allow the expression and purification of multi-KOW domain complexes of the Saccharomyces cerevisiae transcription elongation factor Spt4/5.

Science.gov (United States)

Blythe, Amanda; Gunasekara, Sanjika; Walshe, James; Mackay, Joel P; Hartzog, Grant A; Vrielink, Alice

2014-08-01

Spt4/5 is a hetero-dimeric transcription elongation factor that can both inhibit and promote transcription elongation by RNA polymerase II (RNAPII). However, Spt4/5's mechanism of action remains elusive. Spt5 is an essential protein and the only universally-conserved RNAP-associated transcription elongation factor. The protein contains multiple Kyrpides, Ouzounis and Woese (KOW) domains. These domains, in other proteins, are thought to bind RNA although there is little direct evidence in the literature to support such a function in Spt5. This could be due, at least in part, to difficulties in expressing and purifying recombinant Spt5. When expressed in Escherichia coli (E. coli), Spt5 is innately insoluble. Here we report a new approach for the successful expression and purification of milligram quantities of three different multi-KOW domain complexes of Saccharomyces cerevisiae Spt4/5 for use in future functional studies. Using the E. coli strain Rosetta2 (DE3) we have developed strategies for co-expression of Spt4 and multi-KOW domain Spt5 complexes from the bi-cistronic pET-Duet vector. In a second strategy, Spt4/5 was expressed via co-transformation of Spt4 in the vector pET-M11 with Spt5 ubiquitin fusion constructs in the vector pHUE. We characterized the multi-KOW domain Spt4/5 complexes by Western blot, limited proteolysis, circular dichroism, SDS-PAGE and size exclusion chromatography-multiangle light scattering and found that the proteins are folded with a Spt4:Spt5 hetero-dimeric stoichiometry of 1:1. These expression constructs encompass a larger region of Spt5 than has previously been reported, and will provide the opportunity to elucidate the biological function of the multi-KOW containing Spt5. Copyright © 2014 Elsevier Inc. All rights reserved.

Effect of disulfide and sulfhydryl reagents on abortive and productive elongation catalyzed by ''Escheridia coli'' RNA polymerase

International Nuclear Information System (INIS)

Radlowski, M.; Job, D.

1994-01-01

The effect of disulfide and sulfhydryl reagents on the rate of abortive and productive elongation has been studied using ''Escherichia coli'' RNA polymerase holoenzyme and poly[d(A-T)] as template. In the presence of UTP as a single substrate and UpA as a primer, the enzyme catalyzed efficiently the synthesis of the trinucleotide product UpApU. Incubation of RNA polymerase with 1 mM 2-mercaptoethanol resulted in a 5-fold increase of the rate of UpApU synthesis. In contrast, incubation of the enzyme with 1 mM 5,5'-dithio-bis(2-nitrobenzoic) acid resulted in a 6-fold decrease of the rate of abortive elongation. Determination of the steady state kinetic constants associated with UpApU synthesis disclosed that the disulfide and sulfhydryl reagents mainly affected the rate of UpApU release from the ternary transcription complexes and therefore influenced the stability of such complexes. (author). 15 refs, 1 fig., 1 tab

Investigation of functional aspects of the N-terminal region of elongation factor Tu from Escherichia coli using a protein engineering approach

DEFF Research Database (Denmark)

Laurberg, M; Mansilla, Francisco; Clark, Brian F. C.

1998-01-01

The function of the N-terminal region of elongation factor Tu is still unexplained. Until recently, it has not been visible in electron density maps from x-ray crystallography studies, but the presence of several well conserved basic residues suggest that this part of the molecule is of structural...

Effector region of the translation elongation factor EF-Tu.GTP complex stabilizes an orthoester acid intermediate structure of aminoacyl-tRNA in a ternary complex.

Science.gov (United States)

Förster, C; Limmer, S; Zeidler, W; Sprinzl, M

1994-01-01

tRNA(Val) from Escherichia coli was aminoacylated with [1-13C]valine and its complex with Thermus thermophilus elongation factor EF-Tu.GTP was analyzed by 13C NMR spectroscopy. The results suggest that the aminoacyl residue of the valyl-tRNA in ternary complex with bacterial EF-Tu and GTP is not attached to tRNA by a regular ester bond to either a 2'- or 3'-hydroxyl group; instead, an intermediate orthoester acid structure with covalent linkage to both vicinal hydroxyls of the terminal adenosine-76 is formed. Mutation of arginine-59 located in the effector region of EF-Tu, a conserved residue in protein elongation factors and the alpha subunits of heterotrimeric guanine nucleotide-binding regulatory proteins (G proteins), abolishes the stabilization of the orthoester acid structure of aminoacyl-tRNA. PMID:8183898

(R)-β-lysine-modified elongation factor P functions in translation elongation

DEFF Research Database (Denmark)

Bullwinkle, Tammy J; Zou, S Betty; Rajkovic, Andrei

2013-01-01

Post-translational modification of bacterial elongation factor P (EF-P) with (R)-β-lysine at a conserved lysine residue activates the protein in vivo and increases puromycin reactivity of the ribosome in vitro. The additional hydroxylation of EF-P at the same lysine residue by the YfcM protein has......-(β)-lysyl-EF-P showed 30% increased puromycin reactivity but no differences in dipeptide synthesis rates when compared with the β-lysylated form. Unlike disruption of the other genes required for EF-P modification, deletion of yfcM had no phenotypic consequences in Salmonella. Taken together, our findings indicate...

Towards an understanding of structure-function relationships of elongation factor Tu

DEFF Research Database (Denmark)

Wiborg, O; Andersen, C; Knudsen, Charlotte Rohde

1994-01-01

In light of the recently determined structure of elongation factor Tu, and taking into account chemical studies mapping functional sites, a number of residues have been selected for site-directed mutagenesis studies. Gly94, Gly126, His66, His118, Lys89 and Asp90 have each been point-mutated. Prel......In light of the recently determined structure of elongation factor Tu, and taking into account chemical studies mapping functional sites, a number of residues have been selected for site-directed mutagenesis studies. Gly94, Gly126, His66, His118, Lys89 and Asp90 have each been point...

Enhanced phosphoserine insertion during Escherichia coli protein synthesis via partial UAG codon reassignment and release factor 1 deletion

Science.gov (United States)

Heinemann, Ilka U.; Rovner, Alexis J.; Aerni, Hans R.; Rogulina, Svetlana; Cheng, Laura; Olds, William; Fischer, Jonathan T.; Söll, Dieter; Isaacs, Farren J.; Rinehart, Jesse

2012-01-01

Genetically encoded phosphoserine incorporation programmed by the UAG codon was achieved by addition of engineered elongation factor and an archaeal aminoacyl-tRNA synthetase to the normal Escherichia coli translation machinery (Park (2011) Science 333, 1151). However, protein yield suffers from expression of the orthogonal phosphoserine translation system and competition with release factor 1 (RF-1). In a strain lacking RF-1, phosphoserine phosphatase, and where 7 UAG codons residing in essential genes were converted to UAA, phosphoserine incorporation into GFP and WNK4 was significantly elevated, but with an accompanying loss in cellular fitness and viability. PMID:22982858

Immunochemical determination of cellular content of translation release factor RF4 in Escherichia coli

DEFF Research Database (Denmark)

Andersen, Lars Dyrskjøt; Manuel Palacios Moreno, Juan; Clark, Brian F. C.

1999-01-01

of the stop codons, and RF3 is known to accelerate the overall termination process. Release factor RF4 is a protein involved in the release of the mRNA and tRNA from the ribosomal complex. Furthermore, RF4 is involved in the proofreading in the elongation step of protein biosynthesis. The cellular contents...... of RF1, RF2, and RF3 were determined earlier. Here we report the cellular content of RF4 in Escherichia coli to be approximately 16,500 molecules per cell. The cells were grown in a rich medium and harvested in the beginning of the exponential growth phase. The quantifications were performed by using...

The crystal structure of elongation factor G complexed with GDP, at 2.7 A resolution.

OpenAIRE

Czworkowski, J; Wang, J; Steitz, T A; Moore, P B

1994-01-01

Elongation factor G (EF-G) catalyzes the translocation step of protein synthesis in bacteria, and like the other bacterial elongation factor, EF-Tu--whose structure is already known--it is a member of the GTPase superfamily. We have determined the crystal structure of EF-G--GDP from Thermus thermophilus. It is an elongated molecule whose large, N-terminal domain resembles the G domain of EF-Tu, except for a 90 residue insert, which covers a surface that is involved in nucleotide exchange in E...

Eukaryotic elongation factor 2 controls TNF-α translation in LPS-induced hepatitis

Science.gov (United States)

González-Terán, Bárbara; Cortés, José R.; Manieri, Elisa; Matesanz, Nuria; Verdugo, ρngeles; Rodríguez, María E.; González-Rodríguez, ρgueda; Valverde, ρngela; Martín, Pilar; Davis, Roger J.; Sabio, Guadalupe

2012-01-01

Bacterial LPS (endotoxin) has been implicated in the pathogenesis of acute liver disease through its induction of the proinflammatory cytokine TNF-α. TNF-α is a key determinant of the outcome in a well-established mouse model of acute liver failure during septic shock. One possible mechanism for regulating TNF-α expression is through the control of protein elongation during translation, which would allow rapid cell adaptation to physiological changes. However, the regulation of translational elongation is poorly understood. We found that expression of p38γ/δ MAPK proteins is required for the elongation of nascent TNF-α protein in macrophages. The MKK3/6-p38γ/δ pathway mediated an inhibitory phosphorylation of eukaryotic elongation factor 2 (eEF2) kinase, which in turn promoted eEF2 activation (dephosphorylation) and subsequent TNF-α elongation. These results identify a new signaling pathway that regulates TNF-α production in LPS-induced liver damage and suggest potential cell-specific therapeutic targets for liver diseases in which TNF-α production is involved. PMID:23202732

Reconstitution of Qbeta RNA replicase from a covalently bonded elongation factor Tu-Ts complex

DEFF Research Database (Denmark)

Brown, S; Blumenthal, T

1976-01-01

of these polypeptides, protein synthesis elongation factors EF-Tu and EF-Ts, can be covalently crosslinked with dimethyl suberimidate to form a complex which lacks the ability to catalyze the known host functions catalyzed by the individual elongation factors. Using a previously developed reconstitution system we have...... examined the effects of crosslinking the EF-Tu-Ts complex on reconstituted replicase activity. Renaturation is significantly more efficient when exogenously added native EF-Tu-Ts is crosslinked than when it is not. Crosslinked EF-Tu-Ts can be purified from a crude crosslinked postribosomal supernatant...... by its ability to replace EF-Tu and EF-Ts in the renaturation of denatured Qbeta replicase. A sample of Qbeta replicase with crosslinked EF-Tu-Ts replacing the individual elongation factors was prepared. Although it lacked EF-Tu and EF-Ts activities, it could initiate transcription of both poly...

A Conserved Proline Triplet in Val-tRNA Synthetase and the Origin of Elongation Factor P

Directory of Open Access Journals (Sweden)

Agata L. Starosta

2014-10-01

Full Text Available Bacterial ribosomes stall on polyproline stretches and require the elongation factor P (EF-P to relieve the arrest. Yet it remains unclear why evolution has favored the development of EF-P rather than selecting against the occurrence of polyproline stretches in proteins. We have discovered that only a single polyproline stretch is invariant across all domains of life, namely a proline triplet in ValS, the tRNA synthetase, that charges tRNAVal with valine. Here, we show that expression of ValS in vivo and in vitro requires EF-P and demonstrate that the proline triplet located in the active site of ValS is important for efficient charging of tRNAVal with valine and preventing formation of mischarged Thr-tRNAVal as well as efficient growth of E. coli in vivo. We suggest that the critical role of the proline triplet for ValS activity may explain why bacterial cells coevolved the EF-P rescue system.

Ribosomal elongation factor 4 promotes cell death associated with lethal stress.

Science.gov (United States)

Li, Liping; Hong, Yuzhi; Luan, Gan; Mosel, Michael; Malik, Muhammad; Drlica, Karl; Zhao, Xilin

2014-12-09

Ribosomal elongation factor 4 (EF4) is highly conserved among bacteria, mitochondria, and chloroplasts. However, the EF4-encoding gene, lepA, is nonessential and its deficiency shows no growth or fitness defect. In purified systems, EF4 back-translocates stalled, posttranslational ribosomes for efficient protein synthesis; consequently, EF4 has a protective role during moderate stress. We were surprised to find that EF4 also has a detrimental role during severe stress: deletion of lepA increased Escherichia coli survival following treatment with several antimicrobials. EF4 contributed to stress-mediated lethality through reactive oxygen species (ROS) because (i) the protective effect of a ΔlepA mutation against lethal antimicrobials was eliminated by anaerobic growth or by agents that block hydroxyl radical accumulation and (ii) the ΔlepA mutation decreased ROS levels stimulated by antimicrobial stress. Epistasis experiments showed that EF4 functions in the same genetic pathway as the MazF toxin, a stress response factor implicated in ROS-mediated cell death. The detrimental action of EF4 required transfer-messenger RNA (tmRNA, which tags truncated proteins for degradation and is known to be inhibited by EF4) and the ClpP protease. Inhibition of a protective, tmRNA/ClpP-mediated degradative activity would allow truncated proteins to indirectly perturb the respiratory chain and thereby provide a potential link between EF4 and ROS. The connection among EF4, MazF, tmRNA, and ROS expands a pathway leading from harsh stress to bacterial self-destruction. The destructive aspect of EF4 plus the protective properties described previously make EF4 a bifunctional factor in a stress response that promotes survival or death, depending on the severity of stress. Translation elongation factor 4 (EF4) is one of the most conserved proteins in nature, but it is dispensable. Lack of strong phenotypes for its genetic knockout has made EF4 an enigma. Recent biochemical work has

A transcript cleavage factor of Mycobacterium tuberculosis important for its survival.

Directory of Open Access Journals (Sweden)

Arnab China

Full Text Available After initiation of transcription, a number of proteins participate during elongation and termination modifying the properties of the RNA polymerase (RNAP. Gre factors are one such group conserved across bacteria. They regulate transcription by projecting their N-terminal coiled-coil domain into the active center of RNAP through the secondary channel and stimulating hydrolysis of the newly synthesized RNA in backtracked elongation complexes. Rv1080c is a putative gre factor (MtbGre in the genome of Mycobacterium tuberculosis. The protein enhanced the efficiency of promoter clearance by lowering abortive transcription and also rescued arrested and paused elongation complexes on the GC rich mycobacterial template. Although MtbGre is similar in domain organization and shares key residues for catalysis and RNAP interaction with the Gre factors of Escherichia coli, it could not complement an E. coli gre deficient strain. Moreover, MtbGre failed to rescue E. coli RNAP stalled elongation complexes, indicating the importance of specific protein-protein interactions for transcript cleavage. Decrease in the level of MtbGre reduced the bacterial survival by several fold indicating its essential role in mycobacteria. Another Gre homolog, Rv3788 was not functional in transcript cleavage activity indicating that a single Gre is sufficient for efficient transcription of the M. tuberculosis genome.

The life and death of translation elongation factor 2

DEFF Research Database (Denmark)

Jørgensen, Rene; Merrill, A.R.; Andersen, Gregers Rom

2006-01-01

The eukaryotic elongation factor 2 (eEF2) occupies an essential role in protein synthesis where it catalyses the translocation of the two tRNAs and the mRNA after peptidyl transfer on the 80S ribosome. Recent crystal structures of eEF2 and the cryo-EM reconstruction of its 80S complex now provide...... diphthamide residue, which is ADP-ribosylated by diphtheria toxin from Corynebacterium diphtheriae and exotoxin A from Pseudomonas aeruginosa....

CbtA toxin of Escherichia coli inhibits cell division and cell elongation via direct and independent interactions with FtsZ and MreB.

Science.gov (United States)

Heller, Danielle M; Tavag, Mrinalini; Hochschild, Ann

2017-09-01

The toxin components of toxin-antitoxin modules, found in bacterial plasmids, phages, and chromosomes, typically target a single macromolecule to interfere with an essential cellular process. An apparent exception is the chromosomally encoded toxin component of the E. coli CbtA/CbeA toxin-antitoxin module, which can inhibit both cell division and cell elongation. A small protein of only 124 amino acids, CbtA, was previously proposed to interact with both FtsZ, a tubulin homolog that is essential for cell division, and MreB, an actin homolog that is essential for cell elongation. However, whether or not the toxic effects of CbtA are due to direct interactions with these predicted targets is not known. Here, we genetically separate the effects of CbtA on cell elongation and cell division, showing that CbtA interacts directly and independently with FtsZ and MreB. Using complementary genetic approaches, we identify the functionally relevant target surfaces on FtsZ and MreB, revealing that in both cases, CbtA binds to surfaces involved in essential cytoskeletal filament architecture. We show further that each interaction contributes independently to CbtA-mediated toxicity and that disruption of both interactions is required to alleviate the observed toxicity. Although several other protein modulators are known to target FtsZ, the CbtA-interacting surface we identify represents a novel inhibitory target. Our findings establish CbtA as a dual function toxin that inhibits both cell division and cell elongation via direct and independent interactions with FtsZ and MreB.

Nannocystin A: an Elongation Factor 1 Inhibitor from Myxobacteria with Differential Anti-Cancer Properties.

Science.gov (United States)

Krastel, Philipp; Roggo, Silvio; Schirle, Markus; Ross, Nathan T; Perruccio, Francesca; Aspesi, Peter; Aust, Thomas; Buntin, Kathrin; Estoppey, David; Liechty, Brigitta; Mapa, Felipa; Memmert, Klaus; Miller, Howard; Pan, Xuewen; Riedl, Ralph; Thibaut, Christian; Thomas, Jason; Wagner, Trixie; Weber, Eric; Xie, Xiaobing; Schmitt, Esther K; Hoepfner, Dominic

2015-08-24

Cultivation of myxobacteria of the Nannocystis genus led to the isolation and structure elucidation of a class of novel cyclic lactone inhibitors of elongation factor 1. Whole genome sequence analysis and annotation enabled identification of the putative biosynthetic cluster and synthesis process. In biological assays the compounds displayed anti-fungal and cytotoxic activity. Combined genetic and proteomic approaches identified the eukaryotic translation elongation factor 1α (EF-1α) as the primary target for this compound class. Nannocystin A (1) displayed differential activity across various cancer cell lines and EEF1A1 expression levels appear to be the main differentiating factor. Biochemical and genetic evidence support an overlapping binding site of 1 with the anti-cancer compound didemnin B on EF-1α. This myxobacterial chemotype thus offers an interesting starting point for further investigations of the potential of therapeutics targeting elongation factor 1. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Physicochemical Factors: Impact on Spermagglutination Induced by Escherichia coli

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Kiranjeet Kaur

2014-02-01

Full Text Available Motility is a sensitive parameter of sperm function which is predictive of its fertilization potential in vitro. The decrease in sperm motility may be associated with sperm agglutination and immobilization due to mere presence of bacteria or excretion of bacterial toxic products. Supplementation with various agents like sucrose, mannitol, calcium, and EDTA is well known to improve the sperm motility in vitro. The present study was designed to check any protective role exerted by the addition of different agents on spermatozoal motility against E. coli induced sperm agglutination. 52 semen specimens were screened for the presence of sperm-agglutinating strain of E. coli. Further, influence of various factors, namely, sugars, salts, and chelating agents was studied. Also, the impact of exposure to high temperature and alcohol on sperm-agglutinating efficiency of E. coli was observed. None of the factors could inhibit the sperm agglutination induced by E. coli, except high temperature suggesting the involvement of protein moiety. In addition, it was observed that agglutinating efficiency of E. coli was limited to spermatozoa and RBCs. It may be concluded that sperm-agglutinating property of E. coli is quite stable as various physicochemical factors tested did not show any negative effect on the same except high temperature.

Sigma factors in a thousand E. coli genomes

DEFF Research Database (Denmark)

Cook, Helen Victoria; Ussery, David

2013-01-01

, 2013), only less than half (983) are of sufficient quality to use in comparative genomic work. Unfortunately, even some of the ‘complete’ E. coli genomes are in pieces, and a few ‘draft’ genomes are good quality. Six of the seven known sigma factors in E. coli strain K‐12 are extremely well conserved...

Comparative genomics and transcriptomics of Escherichia coli isolates carrying virulence factors of both enteropathogenic and enterotoxigenic E. coli.

Science.gov (United States)

Hazen, Tracy H; Michalski, Jane; Luo, Qingwei; Shetty, Amol C; Daugherty, Sean C; Fleckenstein, James M; Rasko, David A

2017-06-14

Escherichia coli that are capable of causing human disease are often classified into pathogenic variants (pathovars) based on their virulence gene content. However, disease-associated hybrid E. coli, containing unique combinations of multiple canonical virulence factors have also been described. Such was the case of the E. coli O104:H4 outbreak in 2011, which caused significant morbidity and mortality. Among the pathovars of diarrheagenic E. coli that cause significant human disease are the enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli (ETEC). In the current study we use comparative genomics, transcriptomics, and functional studies to characterize isolates that contain virulence factors of both EPEC and ETEC. Based on phylogenomic analysis, these hybrid isolates are more genomically-related to EPEC, but appear to have acquired ETEC virulence genes. Global transcriptional analysis using RNA sequencing, demonstrated that the EPEC and ETEC virulence genes of these hybrid isolates were differentially-expressed under virulence-inducing laboratory conditions, similar to reference isolates. Immunoblot assays further verified that the virulence gene products were produced and that the T3SS effector EspB of EPEC, and heat-labile toxin of ETEC were secreted. These findings document the existence and virulence potential of an E. coli pathovar hybrid that blurs the distinction between E. coli pathovars.

Doc toxin is a kinase that inactivates elongation factor Tu.

Science.gov (United States)

Cruz, Jonathan W; Rothenbacher, Francesca P; Maehigashi, Tatsuya; Lane, William S; Dunham, Christine M; Woychik, Nancy A

2014-03-14

The Doc toxin from bacteriophage P1 (of the phd-doc toxin-antitoxin system) has served as a model for the family of Doc toxins, many of which are harbored in the genomes of pathogens. We have shown previously that the mode of action of this toxin is distinct from the majority derived from toxin-antitoxin systems: it does not cleave RNA; in fact P1 Doc expression leads to mRNA stabilization. However, the molecular triggers that lead to translation arrest are not understood. The presence of a Fic domain, albeit slightly altered in length and at the catalytic site, provided a clue to the mechanism of P1 Doc action, as most proteins with this conserved domain inactivate GTPases through addition of an adenylyl group (also referred to as AMPylation). We demonstrated that P1 Doc added a single phosphate group to the essential translation elongation factor and GTPase, elongation factor (EF)-Tu. The phosphorylation site was at a highly conserved threonine, Thr-382, which was blocked when EF-Tu was treated with the antibiotic kirromycin. Therefore, we have established that Fic domain proteins can function as kinases. This distinct enzymatic activity exhibited by P1 Doc also solves the mystery of the degenerate Fic motif unique to the Doc family of toxins. Moreover, we have established that all characterized Fic domain proteins, even those that phosphorylate, target pivotal GTPases for inactivation through a post-translational modification at a single functionally critical acceptor site.

Transcription elongation factors are involved in programming hormone production in pituitary neuroendocrine GH4C1 cells.

Science.gov (United States)

Fujita, Toshitsugu; Piuz, Isabelle; Schlegel, Werner

2010-05-05

Transcription elongation of many eukaryotic genes is regulated. Two negative transcription elongation factors, 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) sensitivity-inducing factor (DSIF) and negative elongation factor (NELF) are known to stall collaboratively RNA polymerase II promoter proximally. We discovered that DSIF and NELF are linked to hormone expression in rat pituitary GH4C1 cells. When NELF-E, a subunit of NELF or Spt5, a subunit of DSIF was stably knocked-down, prolactin (PRL) expression was increased both at the mRNA and protein levels. In contrast, stable knock-down of only Spt5 abolished growth hormone (GH) expression. Transient NELF-E knock-down increased coincidentally PRL expression and enhanced transcription of a PRL-promoter reporter gene. However, no direct interaction of NELF with the PRL gene could be demonstrated by chromatin immuno-precipitation. Thus, NELF suppressed PRL promoter activity indirectly. In conclusion, transcription regulation by NELF and DSIF is continuously involved in the control of hormone production and may contribute to neuroendocrine cell differentiation. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

Substances released from probiotic Lactobacillus rhamnosus GR-1 potentiate NF-κB activity in Escherichia coli-stimulated urinary bladder cells.

Science.gov (United States)

Karlsson, Mattias; Scherbak, Nikolai; Khalaf, Hazem; Olsson, Per-Erik; Jass, Jana

2012-11-01

Lactobacillus rhamnosus GR-1 is a probiotic bacterium used to maintain urogenital health. The putative mechanism for its probiotic effect is by modulating the host immunity. Urinary tract infections (UTI) are often caused by uropathogenic Escherichia coli that frequently evade or suppress immune responses in the bladder and can target pathways, including nuclear factor-kappaB (NF-κB). We evaluated the role of L. rhamnosus GR-1 on NF-κB activation in E. coli-stimulated bladder cells. Viable L. rhamnosus GR-1 was found to potentiate NF-κB activity in E. coli-stimulated T24 bladder cells, whereas heat-killed lactobacilli demonstrated a marginal increase in NF-κB activity. Surface components released by trypsin- or LiCl treatment, or the resultant heat-killed shaved lactobacilli, had no effect on NF-κB activity. Isolation of released products from L. rhamnosus GR-1 demonstrated that the induction of NF-κB activity was owing to released product(s) with a relatively large native size. Several putative immunomodulatory proteins were identified, namely GroEL, elongation factor Tu and NLP/P60. GroEL and elongation factor Tu have previously been shown to elicit immune responses from human cells. Isolating and using immune-augmenting substances produced by lactobacilli is a novel strategy for the prevention or treatment of UTI caused by immune-evading E. coli. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Ubiquitylation and degradation of elongating RNA polymerase II

DEFF Research Database (Denmark)

Wilson, Marcus D; Harreman, Michelle; Svejstrup, Jesper Q

2013-01-01

During its journey across a gene, RNA polymerase II has to contend with a number of obstacles to its progression, including nucleosomes, DNA-binding proteins, DNA damage, and sequences that are intrinsically difficult to transcribe. Not surprisingly, a large number of elongation factors have....... In this review, we describe the mechanisms and factors responsible for the last resort mechanism of transcriptional elongation. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation....

Bacterial elongation factors EF-Tu, their mutants, chimeric forms, and domains: isolation and purification

Czech Academy of Sciences Publication Activity Database

Jonák, Jiří

2007-01-01

Roč. 849, 1-2 (2007), s. 141-153 ISSN 1570-0232 R&D Projects: GA AV ČR IAA5052206; GA AV ČR KJB500520503; GA MŠk 2B06065 Institutional research plan: CEZ:AV0Z50520514 Keywords : bacterial elongation factors EF-Tu, , G-domain * recombinant EF-Tus * preparation Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.935, year: 2007

Doc Toxin Is a Kinase That Inactivates Elongation Factor Tu*

Science.gov (United States)

Cruz, Jonathan W.; Rothenbacher, Francesca P.; Maehigashi, Tatsuya; Lane, William S.; Dunham, Christine M.; Woychik, Nancy A.

2014-01-01

The Doc toxin from bacteriophage P1 (of the phd-doc toxin-antitoxin system) has served as a model for the family of Doc toxins, many of which are harbored in the genomes of pathogens. We have shown previously that the mode of action of this toxin is distinct from the majority derived from toxin-antitoxin systems: it does not cleave RNA; in fact P1 Doc expression leads to mRNA stabilization. However, the molecular triggers that lead to translation arrest are not understood. The presence of a Fic domain, albeit slightly altered in length and at the catalytic site, provided a clue to the mechanism of P1 Doc action, as most proteins with this conserved domain inactivate GTPases through addition of an adenylyl group (also referred to as AMPylation). We demonstrated that P1 Doc added a single phosphate group to the essential translation elongation factor and GTPase, elongation factor (EF)-Tu. The phosphorylation site was at a highly conserved threonine, Thr-382, which was blocked when EF-Tu was treated with the antibiotic kirromycin. Therefore, we have established that Fic domain proteins can function as kinases. This distinct enzymatic activity exhibited by P1 Doc also solves the mystery of the degenerate Fic motif unique to the Doc family of toxins. Moreover, we have established that all characterized Fic domain proteins, even those that phosphorylate, target pivotal GTPases for inactivation through a post-translational modification at a single functionally critical acceptor site. PMID:24448800

Risk factors for ceftiofur resistance in Escherichia coli from Belgian broilers.

Science.gov (United States)

Persoons, D; Haesebrouck, F; Smet, A; Herman, L; Heyndrickx, M; Martel, A; Catry, B; Berge, A C; Butaye, P; Dewulf, J

2011-05-01

A cross-sectional study on 32 different Belgian broiler farms was performed in 2007 and 2008 to identify risk factors for ceftiofur resistance in Escherichia coli. On each farm, one E. coli colony was isolated from 30 random birds. Following susceptibility testing of 14 antimicrobials, an on-farm questionnaire was used to obtain information on risk factors. Using a multilevel logistic regression model two factors were identified at the animal level: resistance to amoxicillin and to trimethoprim-sulfonamide. On the farm level, besides antimicrobial use, seven management factors were found to be associated with the occurrence of ceftiofur resistance in E. coli from broilers: poor hygienic condition of the medicinal treatment reservoir, no acidification of drinking water, more than three feed changes during the production cycle, hatchery of origin, breed, litter material used, and treatment with amoxicillin. This study confirms that not only on-farm antimicrobial therapy, but also management- and hatchery-related factors influence the occurrence of antimicrobial resistance.

Synthesis of Elongated Microcapsules

Science.gov (United States)

Li, Wenyan; Buhrow, Jerry; Calle, Luz M.

2011-01-01

One of the factors that influence the effectiveness of self-healing in functional materials is the amount of liquid healing agents that can be delivered to the damaged area. The use of hollow tubes or fibers and the more sophisticated micro-vascular networks has been proposed as a way to increase the amount of healing agents that can be released when damage is inflicted. Although these systems might be effective in some specific applications, they are not practical for coatings applications. One possible practical way to increase the healing efficiency is to use microcapsules with high-aspect-ratios, or elongated microcapsules. It is understood that elongated microcapsules will be more efficient because they can release more healing agent than a spherical microcapsule when a crack is initiated in the coating. Although the potential advantage of using elongated microcapsules for self healing applications is clear, it is very difficult to make elongated microcapsules from an emulsion system because spherical microcapsules are normally formed due to the interfacial tension between the dispersed phase and the continuous phase. This paper describes the two methods that have been developed by the authors to synthesize elongated microcapsules. The first method involves the use of an emulsion with intermediate stability and the second involves the application of mechanical shear conditions to the emulsion.

The surface-associated elongation factor Tu is concealed for antibody binding on viable pneumococci and meningococci

Czech Academy of Sciences Publication Activity Database

Kolberg, J.; Hammerschmidt, S.; Frank, R.; Jonák, Jiří; Šanderová, Hana; Aase, A.

2008-01-01

Roč. 53, č. 2 (2008), s. 222-230 ISSN 0928-8244 R&D Projects: GA AV ČR KJB500520503 Institutional research plan: CEZ:AV0Z50520514; CEZ:AV0Z50200510 Keywords : Streptococcus pneumoniae * Neisseria meningitidis * elongation factor EF-Tu Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.972, year: 2008

How much territory can a single E. coli cell control?

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Ziad W. El-Hajj

2015-04-01

Full Text Available Bacteria have been traditionally classified in terms of size and shape and are best known for their very small size. E. coli cells in particular are small rods, each 1-2 microns. However the size varies with the medium, and faster growing cells are larger because they must have more ribosomes to make more protoplasm per unit time, and ribosomes take up space. Indeed, Maaloe's experiments on how E. coli establishes its size began with shifts between rich and poor media.Recently much larger bacteria have been described, including Epulopiscium fishelsoni at 700 μm and Thiomargarita namibiensisis at 750 μm. These are not only much longer than E. coli cells but also much wider, necessitating considerable intracellular organization. Epulopiscium cells for instance, at 80 μm wide, enclose a large enough volume of cytoplasm to present it with major transport problems.This review surveys E. coli cells much longer than those which grow in nature and in usual lab cultures. These include cells mutated in a single gene (metK which are 2-4x longer than their nonmutated parent. This metK mutant stops dividing when slowly starved of S-adenosylmethionine but continues to elongate to 50 μm and more. FtsZ mutants have been routinely isolated as long cells which form during growth at 42°C. The SOS response is a well-characterized regulatory network that is activated in response to DNA damage and also results in cell elongation. Our champion elongated E. coli is a metK strain with a further, as yet unidentified mutation, which reaches 750 μm with no internal divisions and no increase in width.

Vaccination with Eimeria tenella elongation factor-1α recombinant protein induces protective immunity against E. tenella and E. maxima infections.

Science.gov (United States)

Lin, Rui-Qing; Lillehoj, Hyun S; Lee, Seung Kyoo; Oh, Sungtaek; Panebra, Alfredo; Lillehoj, Erik P

2017-08-30

Avian coccidiosis is caused by multiple species of the apicomplexan protozoan, Eimeria, and is one of the most economically devastating enteric diseases for the poultry industry worldwide. Host immunity to Eimeria infection, however, is relatively species-specific. The ability to immunize chickens against different species of Eimeria using a single vaccine will have a major beneficial impact on commercial poultry production. In this paper, we describe the molecular cloning, purification, and vaccination efficacy of a novel Eimeria vaccine candidate, elongation factor-1α (EF-1α). One day-old broiler chickens were given two subcutaneous immunizations one week apart with E. coli-expressed E. tenella recombinant (r)EF-1α protein and evaluated for protection against challenge infection with E. tenella or E. maxima. rEF-1α-vaccinated chickens exhibited increased body weight gains, decreased fecal oocyst output, and greater serum anti-EF-1α antibody levels following challenge infection with either E. tenella or E. maxima compared with unimmunized controls. Vaccination with EF-1α may represent a new approach to inducing cross-protective immunity against avian coccidiosis in the field. Published by Elsevier B.V.

A non-catalytic N-terminal domain negatively influences the nucleotide exchange activity of translation elongation factor 1Bα.

Science.gov (United States)

Trosiuk, Tetiana V; Shalak, Vyacheslav F; Szczepanowski, Roman H; Negrutskii, Boris S; El'skaya, Anna V

2016-02-01

Eukaryotic translation elongation factor 1Bα (eEF1Bα) is a functional homolog of the bacterial factor EF-Ts, and is a component of the macromolecular eEF1B complex. eEF1Bα functions as a catalyst of guanine nucleotide exchange on translation elongation factor 1A (eEF1A). The C-terminal domain of eEF1Bα is necessary and sufficient for its catalytic activity, whereas the N-terminal domain interacts with eukaryotic translation elongation factor 1Bγ (eEF1Bγ) to form a tight complex. However, eEF1Bγ has been shown to enhance the catalytic activity of eEF1Bα attributed to the C-terminal domain of eEF1Bα. This suggests that the N-terminal domain of eEF1Bα may in some way influence the guanine nucleotide exchange process. We have shown that full-length recombinant eEF1Bα and its truncated forms are non-globular proteins with elongated shapes. Truncation of the N-terminal domain of eEF1Bα, which is dispensable for catalytic activity, resulted in acceleration of the rate of guanine nucleotide exchange on eEF1A compared to full-length eEF1Bα. A similar effect on the catalytic activity of eEF1Bα was observed after its interaction with eEF1Bγ. We suggest that the non-catalytic N-terminal domain of eEF1Bα may interfere with eEF1A binding to the C-terminal catalytic domain, resulting in a decrease in the overall rate of the guanine nucleotide exchange reaction. Formation of a tight complex between the eEF1Bγ and eEF1Bα N-terminal domains abolishes this inhibitory effect. © 2015 FEBS.

Virulence Factors and Antibiotic Resistance in Uropathogenic and Commensal Escherichia coli Isolates

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Iraj Sedighi

2016-10-01

Full Text Available Background: Urinary Tract Infections (UTIs, including cystitis and pyelonephritis, are the most common infectious diseases in childhood. Aim and Objectives: Escherichia coli (E. coli account for as much as 90% of the community-acquired and also 50% of nosocomial UTIs. Therefore, the identification of E. coli strains and antibiotic resistance patterns is important for both clinical and epidemiological implications. Material and Methods: To characterize uropathogenic strains E. coli, we studied 100 strains recovered from both urine samples of children aged less than 7 years with community-acquired UTIs and stool samples of healthy children, respectively. Results: We assessed Virulence Factors (VFs and drug sensitivities of E. coli isolates. Drug sensitivities of the isolates were 94% (amikacin, 90% (nitrofurantoin, 66% (gentamicin, 56% (cefixime, 40% (nalidixic acid and 28% (cotrimoxazol. Laboratory tests showed that the prevalence of virulence factors ranged from 18% for hemolysin and P-fimbriae to 2% for type1-fimbriae. Most drug resistance was cotrimoxazole and amikacin was the lowest. P-fimbriae and hemolysin in uropathogenic E. coli were more frequent than non-pathogen type of E. coli. Conclusion: Although amikacin appeared to be the first choice for UTI in children, but nitrofurantoin seems to be practical and could be considered as the selective choice for uncomplicated lower UTIs.

Escherichia coli DnaE Polymerase Couples Pyrophosphatase Activity to DNA Replication.

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Fabio Lapenta

Full Text Available DNA Polymerases generate pyrophosphate every time they catalyze a step of DNA elongation. This elongation reaction is generally believed as thermodynamically favoured by the hydrolysis of pyrophosphate, catalyzed by inorganic pyrophosphatases. However, the specific action of inorganic pyrophosphatases coupled to DNA replication in vivo was never demonstrated. Here we show that the Polymerase-Histidinol-Phosphatase (PHP domain of Escherichia coli DNA Polymerase III α subunit features pyrophosphatase activity. We also show that this activity is inhibited by fluoride, as commonly observed for inorganic pyrophosphatases, and we identified 3 amino acids of the PHP active site. Remarkably, E. coli cells expressing variants of these catalytic residues of α subunit feature aberrant phenotypes, poor viability, and are subject to high mutation frequencies. Our findings indicate that DNA Polymerases can couple DNA elongation and pyrophosphate hydrolysis, providing a mechanism for the control of DNA extension rate, and suggest a promising target for novel antibiotics.

A pea chloroplast translation elongation factor that is regulated by abiotic factors

International Nuclear Information System (INIS)

Singh, B.N.; Mishra, R.N.; Agarwal, Pradeep K.; Goswami, Mamta; Nair, Suresh; Sopory, S.K.; Reddy, M.K.

2004-01-01

We report the cloning and characterization of both the cDNA (tufA) and genomic clones encoding for a chloroplast translation elongation factor (EF-Tu) from pea. The analysis of the deduced amino acids of the cDNA clone reveals the presence of putative transit peptide sequence and four GTP binding domains and two EF-Tu signature motifs in the mature polypeptide region. Using in vivo immunostaining followed by confocal microscopy pea EF-Tu was localized to chloroplast. The steady state transcript level of pea tufA was high in leaves and not detectable in roots. The expression of this gene is stimulated by light. The differential expression of this gene in response to various abiotic stresses showed that it is down-regulated in response to salinity and ABA and up-regulated in response to low temperature and salicylic acid treatment. These results indicate that regulation of pea tufA may have an important role in plant adaptation to environmental stresses

Loss of elongation factor P disrupts bacterial outer membrane integrity

DEFF Research Database (Denmark)

Zou, S Betty; Hersch, Steven J; Roy, Hervé

2012-01-01

background ameliorates the detergent, antibiotic, and osmosensitivity phenotypes and restores wild-type permeability to NPN. Our data support a role for EF-P in the translational regulation of a limited number of proteins that, when perturbed, renders the cell susceptible to stress by the adventitious......Elongation factor P (EF-P) is posttranslationally modified at a conserved lysyl residue by the coordinated action of two enzymes, PoxA and YjeK. We have previously established the importance of this modification in Salmonella stress resistance. Here we report that, like poxA and yjeK mutants......, Salmonella strains lacking EF-P display increased susceptibility to hypoosmotic conditions, antibiotics, and detergents and enhanced resistance to the compound S-nitrosoglutathione. The susceptibility phenotypes are largely explained by the enhanced membrane permeability of the efp mutant, which exhibits...

Uniaxial Elongational viscosity of bidisperse polystyrene melts

DEFF Research Database (Denmark)

Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole

2006-01-01

The startup and steady uniaxial elongational viscosity have been measured for three bidisperse polystyrene (PS) melts, consisting of blends of monodisperse PS with molecular weights of 52 kg/mole or 103 kg/mole and 390 kg/mole. The bidisperse melts have a maximum in the steady elongational...... viscosity, of up to a factor of 7 times the Trouton limit of 3 times the zero-shear viscosity....

Rice ethylene-response AP2/ERF factor OsEATB restricts internode elongation by down-regulating a gibberellin biosynthetic gene.

Science.gov (United States)

Qi, Weiwei; Sun, Fan; Wang, Qianjie; Chen, Mingluan; Huang, Yunqing; Feng, Yu-Qi; Luo, Xiaojin; Yang, Jinshui

2011-09-01

Plant height is a decisive factor in plant architecture. Rice (Oryza sativa) plants have the potential for rapid internodal elongation, which determines plant height. A large body of physiological research has shown that ethylene and gibberellin are involved in this process. The APETALA2 (AP2)/Ethylene-Responsive Element Binding Factor (ERF) family of transcriptional factors is only present in the plant kingdom. This family has various developmental and physiological functions. A rice AP2/ERF gene, OsEATB (for ERF protein associated with tillering and panicle branching) was cloned from indica rice variety 9311. Bioinformatic analysis suggested that this ERF has a potential new function. Ectopic expression of OsEATB showed that the cross talk between ethylene and gibberellin, which is mediated by OsEATB, might underlie differences in rice internode elongation. Analyses of gene expression demonstrated that OsEATB restricts ethylene-induced enhancement of gibberellin responsiveness during the internode elongation process by down-regulating the gibberellin biosynthetic gene, ent-kaurene synthase A. Plant height is negatively correlated with tiller number, and higher yields are typically obtained from dwarf crops. OsEATB reduces rice plant height and panicle length at maturity, promoting the branching potential of both tillers and spikelets. These are useful traits for breeding high-yielding crops.

Film dosimetry of small elongated electron beams for treatment planning

International Nuclear Information System (INIS)

Niroomand-Rad, A.

1989-01-01

The characteristics of 5, 7, 10, 12, 15, and 18 Mev electron beams for small elongated fields of dimensions L x W (where L=1, 2, 3, 4, 5, and 10 cm; and W=1, 2, 3, 4, 5, and 10 cm) have been studied. Film dosimetry and parallel-plate ion chamber measurements have been used to obtain various dose parameters. Selective results of a series of systematic measurements for central axis depth dose data, uniformity index, field flatness, and relative output factors of small elongated electron beams are reported. The square-root method is employed to predict the beam data of small elongated electron fields from corresponding small square electron fields using film dosimetry. The single parameter area/perimeter radio A/P is used to characterize the relative output factors of elongated electron beams. It is our conclusion that for clinical treatment planning square-root method may be applied with caution in determining the beam characteristics of small elongated electron fields from film dosimetry. The calculated and estimated relative output factors from square-root method and A/P ratio are in good agreement and show agreement to within 1% with the measured film values

The cauliflower Orange gene enhances petiole elongation by suppressing expression of eukaryotic release factor 1.

Science.gov (United States)

Zhou, Xiangjun; Sun, Tian-Hu; Wang, Ning; Ling, Hong-Qing; Lu, Shan; Li, Li

2011-04-01

The cauliflower (Brassica oleracea var. botrytis) Orange (Or) gene affects plant growth and development in addition to conferring β-carotene accumulation. This study was undertaken to investigate the molecular basis for the effects of the Or gene mutation in on plant growth. The OR protein was found to interact with cauliflower and Arabidopsis eukaryotic release factor 1-2 (eRF1-2), a member of the eRF1 family, by yeast two-hybrid analysis and by bimolecular fluorescence complementation (BiFC) assay. Concomitantly, the Or mutant showed reduced expression of the BoeRF1 family genes. Transgenic cauliflower plants with suppressed expression of BoeRF1-2 and BoeRF1-3 were generated by RNA interference. Like the Or mutant, the BoeRF1 RNAi lines showed increased elongation of the leaf petiole. This long-petiole phenotype was largely caused by enhanced cell elongation, which resulted from increased cell length and elevated expression of genes involved in cell-wall loosening. These findings demonstrate that the cauliflower Or gene controls petiole elongation by suppressing the expression of eRF1 genes, and provide new insights into the molecular mechanism of leaf petiole regulation. © 2010 The Authors. New Phytologist © 2010 New Phytologist Trust.

Engineering of methionine chain elongation part of glucoraphanin pathway in E. coli

DEFF Research Database (Denmark)

Mirza, Nadia Muhammad Akram; Crocoll, Christoph; Olsen, Carl Erik

2016-01-01

The methionine-derived glucosinolate glucoraphanin is associated with the health-promoting properties of broccoli. This has developed a strong interest in producing this compound in high amounts from a microbial source. Glucoraphanin synthesis starts with a five-gene chain elongation pathway...

Recombination Phenotypes of Escherichia coli greA Mutants

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Poteete Anthony R

2011-03-01

Full Text Available Abstract Background The elongation factor GreA binds to RNA polymerase and modulates transcriptional pausing. Some recent research suggests that the primary role of GreA may not be to regulate gene expression, but rather, to promote the progression of replication forks which collide with RNA polymerase, and which might otherwise collapse. Replication fork collapse is known to generate dsDNA breaks, which can be recombinogenic. It follows that GreA malfunction could have consequences affecting homologous recombination. Results Escherichia coli mutants bearing substitutions of the active site acidic residues of the transcription elongation factor GreA, D41N and E44K, were isolated as suppressors of growth inhibition by a toxic variant of the bacteriophage lambda Red-beta recombination protein. These mutants, as well as a D41A greA mutant and a greA deletion, were tested for proficiency in recombination events. The mutations were found to increase the efficiency of RecA-RecBCD-mediated and RecA-Red-mediated recombination, which are replication-independent, and to decrease the efficiency of replication-dependent Red-mediated recombination. Conclusion These observations provide new evidence for a role of GreA in resolving conflicts between replication and transcription.

Response of Escherichia coli growth rate to osmotic shock.

Science.gov (United States)

Rojas, Enrique; Theriot, Julie A; Huang, Kerwyn Casey

2014-05-27

It has long been proposed that turgor pressure plays an essential role during bacterial growth by driving mechanical expansion of the cell wall. This hypothesis is based on analogy to plant cells, for which this mechanism has been established, and on experiments in which the growth rate of bacterial cultures was observed to decrease as the osmolarity of the growth medium was increased. To distinguish the effect of turgor pressure from pressure-independent effects that osmolarity might have on cell growth, we monitored the elongation of single Escherichia coli cells while rapidly changing the osmolarity of their media. By plasmolyzing cells, we found that cell-wall elastic strain did not scale with growth rate, suggesting that pressure does not drive cell-wall expansion. Furthermore, in response to hyper- and hypoosmotic shock, E. coli cells resumed their preshock growth rate and relaxed to their steady-state rate after several minutes, demonstrating that osmolarity modulates growth rate slowly, independently of pressure. Oscillatory hyperosmotic shock revealed that although plasmolysis slowed cell elongation, the cells nevertheless "stored" growth such that once turgor was reestablished the cells elongated to the length that they would have attained had they never been plasmolyzed. Finally, MreB dynamics were unaffected by osmotic shock. These results reveal the simple nature of E. coli cell-wall expansion: that the rate of expansion is determined by the rate of peptidoglycan insertion and insertion is not directly dependent on turgor pressure, but that pressure does play a basic role whereby it enables full extension of recently inserted peptidoglycan.

BolA inhibits cell elongation and regulates MreB expression levels.

Science.gov (United States)

Freire, Patrick; Moreira, Ricardo Neves; Arraiano, Cecília Maria

2009-02-06

The morphogene bolA is a general stress response gene in Escherichia coli that induces a round morphology when overexpressed. Results presented in this report show that increased BolA levels can inhibit cell elongation mechanisms. MreB polymerization is crucial for the bacterial cell cytoskeleton, and this protein is essential for the maintenance of a cellular rod shape. In this report, we demonstrate that bolA overexpression affects the architecture of MreB filaments. An increase in BolA leads to a significant reduction in MreB protein levels and mreB transcripts. BolA affects the mreBCD operon in vivo at the level of transcription. Furthermore, our results show that BolA is a new transcriptional repressor of MreB. The alterations in cell morphology induced by bolA seem to be mediated by a complex pathway that integrates PBP5, PBP6, MreB, and probably other regulators of cell morphology/elongation.

Peroxisome proliferator-activated receptor gamma recruits the positive transcription elongation factor b complex to activate transcription and promote adipogenesis

DEFF Research Database (Denmark)

Iankova, Irena; Petersen, Rasmus K; Annicotte, Jean-Sébastien

2006-01-01

Positive transcription elongation factor b (P-TEFb) phosphorylates the C-terminal domain of RNA polymerase II, facilitating transcriptional elongation. In addition to its participation in general transcription, P-TEFb is recruited to specific promoters by some transcription factors such as c......-Myc or MyoD. The P-TEFb complex is composed of a cyclin-dependent kinase (cdk9) subunit and a regulatory partner (cyclin T1, cyclin T2, or cyclin K). Because cdk9 has been shown to participate in differentiation processes, such as muscle cell differentiation, we studied a possible role of cdk9...... with and phosphorylation of peroxisome proliferator-activated receptor gamma (PPARgamma), which is the master regulator of this process, on the promoter of PPARgamma target genes. PPARgamma-cdk9 interaction results in increased transcriptional activity of PPARgamma and therefore increased adipogenesis....

Heat shock-induced accumulation of translation elongation and termination factors precedes assembly of stress granules in S. cerevisiae.

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Tomas Grousl

Full Text Available In response to severe environmental stresses eukaryotic cells shut down translation and accumulate components of the translational machinery in stress granules (SGs. Since they contain mainly mRNA, translation initiation factors and 40S ribosomal subunits, they have been referred to as dominant accumulations of stalled translation preinitiation complexes. Here we present evidence that the robust heat shock-induced SGs of S. cerevisiae also contain translation elongation factors eEF3 (Yef3p and eEF1Bγ2 (Tef4p as well as translation termination factors eRF1 (Sup45p and eRF3 (Sup35p. Despite the presence of the yeast prion protein Sup35 in heat shock-induced SGs, we found out that its prion-like domain is not involved in the SGs assembly. Factors eEF3, eEF1Bγ2 and eRF1 were accumulated and co-localized with Dcp2 foci even upon a milder heat shock at 42°C independently of P-bodies scaffolding proteins. We also show that eEF3 accumulations at 42°C determine sites of the genuine SGs assembly at 46°C. We suggest that identification of translation elongation and termination factors in SGs might help to understand the mechanism of the eIF2α factor phosphorylation-independent repression of translation and SGs assembly.

Structure discrimination for the C-terminal domain of Escherichia coli trigger factor in solution

International Nuclear Information System (INIS)

Yao Yong; Bhabha, Gira; Kroon, Gerard; Landes, Mindy; Dyson, H. Jane

2008-01-01

NMR measurements can give important information on solution structure, without the necessity for a full-scale solution structure determination. The C-terminal protein binding domain of the ribosome-associated chaperone protein trigger factor is composed of non-contiguous parts of the polypeptide chain, with an interpolated prolyl isomerase domain. A construct of the C-terminal domain of Escherichia coli trigger factor containing residues 113-149 and 247-432, joined by a Gly-Ser-Gly-Ser linker, is well folded and gives excellent NMR spectra in solution. We have used NMR measurements on this construct, and on a longer construct that includes the prolyl isomerase domain, to distinguish between two possible structures for the C-terminal domain of trigger factor, and to assess the behavior of the trigger factor C-terminal domain in solution. Two X-ray crystal structures, of intact trigger factor from E. coli (Ferbitz et al., Nature 431:590-596, 2004), and of a truncated trigger factor from Vibrio cholerae (Ludlam et al., Proc Natl Acad Sci USA 101:13436-13441, 2004) showed significant differences in the structure of the C-terminal domain, such that the two structures could not be superimposed. We show using NMR chemical shifts and long range nuclear Overhauser effects that the secondary and tertiary structure of the E. coli C-terminal domain in solution is consistent with the crystal structure of the E. coli trigger factor and not with the V. cholerae protein. Given the similarity of the amino acid sequences of the E. coli and V. cholerae proteins, it appears likely that the structure of the V. cholerae protein has been distorted as a result of truncation of a 44-amino acid segment at the C-terminus. Analysis of residual dipolar coupling measurements shows that the overall topology of the solution structure is completely inconsistent with both structures. Dynamics analysis of the C-terminal domain using T 1 , T 2 and heteronuclear NOE parameters show that the protein is

Translation elongation factor 1A facilitates the assembly of the tombusvirus replicase and stimulates minus-strand synthesis.

OpenAIRE

Zhenghe Li; Judit Pogany; Steven Tupman; Anthony M Esposito; Terri Goss Kinzy; Peter D Nagy

2010-01-01

Replication of plus-strand RNA viruses depends on host factors that are recruited into viral replicase complexes. Previous studies showed that eukaryotic translation elongation factor (eEF1A) is one of the resident host proteins in the highly purified tombusvirus replicase complex. Using a random library of eEF1A mutants, we identified one mutant that decreased and three mutants that increased Tomato bushy stunt virus (TBSV) replication in a yeast model host. Additional in vitro assays with w...

A Herpesviral Immediate Early Protein Promotes Transcription Elongation of Viral Transcripts.

Science.gov (United States)

Fox, Hannah L; Dembowski, Jill A; DeLuca, Neal A

2017-06-13

Herpes simplex virus 1 (HSV-1) genes are transcribed by cellular RNA polymerase II (RNA Pol II). While four viral immediate early proteins (ICP4, ICP0, ICP27, and ICP22) function in some capacity in viral transcription, the mechanism by which ICP22 functions remains unclear. We observed that the FACT complex (comprised of SSRP1 and Spt16) was relocalized in infected cells as a function of ICP22. ICP22 was also required for the association of FACT and the transcription elongation factors SPT5 and SPT6 with viral genomes. We further demonstrated that the FACT complex interacts with ICP22 throughout infection. We therefore hypothesized that ICP22 recruits cellular transcription elongation factors to viral genomes for efficient transcription elongation of viral genes. We reevaluated the phenotype of an ICP22 mutant virus by determining the abundance of all viral mRNAs throughout infection by transcriptome sequencing (RNA-seq). The accumulation of almost all viral mRNAs late in infection was reduced compared to the wild type, regardless of kinetic class. Using chromatin immunoprecipitation sequencing (ChIP-seq), we mapped the location of RNA Pol II on viral genes and found that RNA Pol II levels on the bodies of viral genes were reduced in the ICP22 mutant compared to wild-type virus. In contrast, the association of RNA Pol II with transcription start sites in the mutant was not reduced. Taken together, our results indicate that ICP22 plays a role in recruiting elongation factors like the FACT complex to the HSV-1 genome to allow for efficient viral transcription elongation late in viral infection and ultimately infectious virion production. IMPORTANCE HSV-1 interacts with many cellular proteins throughout productive infection. Here, we demonstrate the interaction of a viral protein, ICP22, with a subset of cellular proteins known to be involved in transcription elongation. We determined that ICP22 is required to recruit the FACT complex and other transcription

Dynamics of E.coli virulence factors in dairy cow herds

Science.gov (United States)

Background. Dairy farms are known reservoirs of entero-pathogenic E. coli (EPEC). EPEC, or the virulence factors associated with pathogenicity, have been detected in manure, milk, and the farm environment. However, it is unclear which farm compartments are reservoirs contributing to EPEC persistence...

Depletion of elongation initiation factor 4E binding proteins by CRISPR/Cas9 genome editing enhances antiviral response in porcine cells

Science.gov (United States)

Type I interferons (IFN) are key mediators of the innate antiviral response in mammalian cells. Elongation initiation factor 4E binding proteins (4E-BPs) are translational controllers of interferon regulatory factor 7 (IRF7), the master regulator of IFN transcription. The role of 4EBPs in the negat...

Heat-induced accumulation of protein synthesis elongation factor 1A indicates an important role in heat tolerance in potato

Science.gov (United States)

Heat stress substantially reduces crop productivity worldwide, and will become more severe due to global warming. Identification of proteins involved in heat stress response may help develop varieties for heat tolerance. Eukaryotic elongation factor 1A (eEF1A) is a cytosolic, multifunctional protei...

Advances toward DNA-based identification and phylogeny of North American Armillaria species using elongation factor-1 alpha gene

Science.gov (United States)

Amy L. Ross-Davis; John W. Hanna; Mee-Sook Kim; Ned B. Klopfenstein

2012-01-01

The translation elongation factor-1 alpha gene was used to examine the phylogenetic relationships among 30 previously characterized isolates representing ten North American Armillaria species: A. solidipes (=A. ostoyae), A. gemina, A. calvescens, A. sinapina, A. mellea, A. gallica, A. nabsnona, North American biological species X, A. cepistipes, and A. tabescens. The...

Rapid fold and structure determination of the archaeal translation elongation factor 1{beta} from Methanobacterium thermoautotrophicum

Energy Technology Data Exchange (ETDEWEB)

Kozlov, Guennadi [McGill University, Department of Biochemistry (Canada); Ekiel, Irena [National Research Council of Canada, Biomolecular NMR Group, Sector of Pharmaceutical Biotechnology, Biotechnology Research Institute (Canada); Beglova, Natalia [McGill University, Department of Biochemistry (Canada); Yee, Adelinda; Dharamsi, Akil; Engel, Asaph [University of Toronto, Department of Medical Biophysics (Canada); Siddiqui, Nadeem; Nong, Andrew; Gehring, Kalle [McGill University, Department of Biochemistry (Canada)

2000-07-15

The tertiary fold of the elongation factor, aEF-1{beta}, from Methanobacterium thermoautotrophicum was determined in a high-throughput fashion using a minimal set of NMR experiments. NMR secondary structure prediction, deuterium exchange experiments and the analysis of chemical shift perturbations were combined to identify the protein fold as an alpha-beta sandwich typical of many RNA binding proteins including EF-G. Following resolution of the tertiary fold, a high resolution structure of aEF-1{beta} was determined using heteronuclear and homonuclear NMR experiments and a semi-automated NOESY assignment strategy. Analysis of the aEF-1{beta} structure revealed close similarity to its human analogue, eEF-1{beta}. In agreement with studies on EF-Ts and human EF-1{beta}, a functional mechanism for nucleotide exchange is proposed wherein Phe46 on an exposed loop acts as a lever to eject GDP from the associated elongation factor G-protein, aEF-1{alpha}. aEF-1{beta} was also found to bind calcium in the groove between helix {alpha}2 and strand {beta}4. This novel feature was not observed previously and may serve a structural function related to protein stability or may play a functional role in archaeal protein translation.

Rapid fold and structure determination of the archaeal translation elongation factor 1β from Methanobacterium thermoautotrophicum

International Nuclear Information System (INIS)

Kozlov, Guennadi; Ekiel, Irena; Beglova, Natalia; Yee, Adelinda; Dharamsi, Akil; Engel, Asaph; Siddiqui, Nadeem; Nong, Andrew; Gehring, Kalle

2000-01-01

The tertiary fold of the elongation factor, aEF-1β, from Methanobacterium thermoautotrophicum was determined in a high-throughput fashion using a minimal set of NMR experiments. NMR secondary structure prediction, deuterium exchange experiments and the analysis of chemical shift perturbations were combined to identify the protein fold as an alpha-beta sandwich typical of many RNA binding proteins including EF-G. Following resolution of the tertiary fold, a high resolution structure of aEF-1β was determined using heteronuclear and homonuclear NMR experiments and a semi-automated NOESY assignment strategy. Analysis of the aEF-1β structure revealed close similarity to its human analogue, eEF-1β. In agreement with studies on EF-Ts and human EF-1β, a functional mechanism for nucleotide exchange is proposed wherein Phe46 on an exposed loop acts as a lever to eject GDP from the associated elongation factor G-protein, aEF-1α. aEF-1β was also found to bind calcium in the groove between helix α2 and strand β4. This novel feature was not observed previously and may serve a structural function related to protein stability or may play a functional role in archaeal protein translation

Prodigiosin - A Multifaceted Escherichia coli Antimicrobial Agent.

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Tjaša Danevčič

Full Text Available Despite a considerable interest in prodigiosin, the mechanism of its antibacterial activity is still poorly understood. In this work, Escherichia coli cells were treated with prodigiosin to determine its antimicrobial effect on bacterial physiology. The effect of prodigiosin was concentration dependent. In prodigiosin treated cells above MIC value no significant DNA damage or cytoplasmic membrane disintegration was observed. The outer membrane, however, becomes leaky. Cells had severely decreased respiration activity. In prodigiosin treated cells protein and RNA synthesis were inhibited, cells were elongated but could not divide. Pre-treatment with prodigiosin improved E. coli survival rate in media containing ampicillin, kanamycin and erythromycin but not phleomycin. The results suggest that prodigiosin acts as a bacteriostatic agent in E. coli cells. If prodigiosin was diluted, cells resumed growth. The results indicate that prodigiosin has distinct mode of antibacterial action in different bacteria.

The transcription elongation factor Bur1-Bur2 interacts with replication protein A and maintains genome stability during replication stress

DEFF Research Database (Denmark)

Clausing, Emanuel; Mayer, Andreas; Chanarat, Sittinan

2010-01-01

Multiple DNA-associated processes such as DNA repair, replication, and recombination are crucial for the maintenance of genome integrity. Here, we show a novel interaction between the transcription elongation factor Bur1-Bur2 and replication protein A (RPA), the eukaryotic single-stranded DNA......-binding protein with functions in DNA repair, recombination, and replication. Bur1 interacted via its C-terminal domain with RPA, and bur1-¿C mutants showed a deregulated DNA damage response accompanied by increased sensitivity to DNA damage and replication stress as well as increased levels of persisting Rad52...... foci. Interestingly, the DNA damage sensitivity of an rfa1 mutant was suppressed by bur1 mutation, further underscoring a functional link between these two protein complexes. The transcription elongation factor Bur1-Bur2 interacts with RPA and maintains genome integrity during DNA replication stress....

Rice Ethylene-Response AP2/ERF Factor OsEATB Restricts Internode Elongation by Down-Regulating a Gibberellin Biosynthetic Gene1[W][OA

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Qi, Weiwei; Sun, Fan; Wang, Qianjie; Chen, Mingluan; Huang, Yunqing; Feng, Yu-Qi; Luo, Xiaojin; Yang, Jinshui

2011-01-01

Plant height is a decisive factor in plant architecture. Rice (Oryza sativa) plants have the potential for rapid internodal elongation, which determines plant height. A large body of physiological research has shown that ethylene and gibberellin are involved in this process. The APETALA2 (AP2)/Ethylene-Responsive Element Binding Factor (ERF) family of transcriptional factors is only present in the plant kingdom. This family has various developmental and physiological functions. A rice AP2/ERF gene, OsEATB (for ERF protein associated with tillering and panicle branching) was cloned from indica rice variety 9311. Bioinformatic analysis suggested that this ERF has a potential new function. Ectopic expression of OsEATB showed that the cross talk between ethylene and gibberellin, which is mediated by OsEATB, might underlie differences in rice internode elongation. Analyses of gene expression demonstrated that OsEATB restricts ethylene-induced enhancement of gibberellin responsiveness during the internode elongation process by down-regulating the gibberellin biosynthetic gene, ent-kaurene synthase A. Plant height is negatively correlated with tiller number, and higher yields are typically obtained from dwarf crops. OsEATB reduces rice plant height and panicle length at maturity, promoting the branching potential of both tillers and spikelets. These are useful traits for breeding high-yielding crops. PMID:21753115

Resistance trends and risk factors of extended spectrum β-lactamases in Escherichia coli infections in Aleppo, Syria.

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Al-Assil, Bodour; Mahfoud, Maysa; Hamzeh, Abdul Rezzak

2013-07-01

Recently, there has been a notable surge in urinary tract infections (UTIs) by extended spectrum β-lactamase (ESBL)-producing Escherichia coli, which considerably limits treatment options. This study aimed to determine prevalence, phenotypic patterns, and ESBL-production status of E coli in isolates from UTI patients along with uncovering locally relevant risk factors for contracting ESBL-producing E coli infections. One hundred four nonrepetitive urine samples were collected from 3 major hospitals in Aleppo, Syria. Antibiotic susceptibility and ESBL production were studied by disc diffusion and double disk synergy tests according to Clinical Laboratory Standards Institute guidelines. Epidemiologic analysis was done using χ(2) and multivariate logistic regression tests. This study revealed high prevalence of multidrug-resistant (MDR) E coli reaching 63%, whereas ESBL-producing E coli exceeded 52%. The latter exhibited alarmingly elevated levels of coresistance to non-β-lactam antibiotics leading to vast increase in MDR rates in comparison with non-ESBL-producing E coli (83.6% vs 12.2%, respectively). We found previous exposure to third-generation cephalosporins and fluoroquinolones to be a significant risk factor for ESBL-producing E coli infections, in addition to other known factors such as hospitalization and catheterization. Tigecycline and carbapenems demonstrated near perfect efficacy against tested E coli, so they rank high among treatment options. Copyright © 2013 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

Production of active pigment epithelium-derived factor inE. coli.

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Zhang, Tao; Guan, Ming; Lu, Yuan

2005-03-01

Human pigment epithelium-derived factor (PEDF), a neurotrophic factor, is the most potent natural inhibitor of angiogenesis. To produce the active PEDF, the gene coding for the human PEDF protein was expressed in E. coli. The rPEDF protein was expressed at 457 mg l-1 as a soluble protein. The yield of purified GST fusion protein was 14 mg l-1. Purified rPEDF inhibited tube formation in endothelial cells.

Double overexpression of DREB and PIF transcription factors improves drought stress tolerance and cell elongation in transgenic plants.

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Kudo, Madoka; Kidokoro, Satoshi; Yoshida, Takuya; Mizoi, Junya; Todaka, Daisuke; Fernie, Alisdair R; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko

2017-04-01

Although a variety of transgenic plants that are tolerant to drought stress have been generated, many of these plants show growth retardation. To improve drought tolerance and plant growth, we applied a gene-stacking approach using two transcription factor genes: DEHYDRATION-RESPONSIVE ELEMENT-BINDING 1A (DREB1A) and rice PHYTOCHROME-INTERACTING FACTOR-LIKE 1 (OsPIL1). The overexpression of DREB1A has been reported to improve drought stress tolerance in various crops, although it also causes a severe dwarf phenotype. OsPIL1 is a rice homologue of Arabidopsis PHYTOCHROME-INTERACTING FACTOR 4 (PIF4), and it enhances cell elongation by activating cell wall-related gene expression. We found that the OsPIL1 protein was more stable than PIF4 under light conditions in Arabidopsis protoplasts. Transactivation analyses revealed that DREB1A and OsPIL1 did not negatively affect each other's transcriptional activities. The transgenic plants overexpressing both OsPIL1 and DREB1A showed the improved drought stress tolerance similar to that of DREB1A overexpressors. Furthermore, double overexpressors showed the enhanced hypocotyl elongation and floral induction compared with the DREB1A overexpressors. Metabolome analyses indicated that compatible solutes, such as sugars and amino acids, accumulated in the double overexpressors, which was similar to the observations of the DREB1A overexpressors. Transcriptome analyses showed an increased expression of abiotic stress-inducible DREB1A downstream genes and cell elongation-related OsPIL1 downstream genes in the double overexpressors, which suggests that these two transcription factors function independently in the transgenic plants despite the trade-offs required to balance plant growth and stress tolerance. Our study provides a basis for plant genetic engineering designed to overcome growth retardation in drought-tolerant transgenic plants. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology

Mutations in the gene for EF-G reduce the requirement for 4.5S RNA in the growth of E. coli

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Brown, S

1987-01-01

A general strategy is described for the isolation of suppressors of essential genes whose functions are unknown. This strategy was used to analyze the role of 4.5S RNA, an essential RNA of E. coli. In this strategy, the structural gene for 4.5S RNA is fused to the Ptac promoter in such a way...... that the strain becomes dependent upon inducers of lac for growth. Mutants mapping to fus, the structural gene for protein synthesis elongation factor G, appear as spontaneous, inducer-independent revertants. These mutants alter the intracellular distribution of 4.5S RNA such that it sediments at 70S or greater....... Furthermore, the increased sedimentation velocity is sensitive to the antibiotic puromycin. These results show that 4.5S RNA physically associates with the ribosome in performing its essential function, and that this association is mediated by elongation factor G....

Generic Escherichia coli contamination of spinach at the preharvest stage: effects of farm management and environmental factors.

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Park, Sangshin; Navratil, Sarah; Gregory, Ashley; Bauer, Arin; Srinath, Indumathi; Jun, Mikyoung; Szonyi, Barbara; Nightingale, Kendra; Anciso, Juan; Ivanek, Renata

2013-07-01

The objective of this study was to determine the effects of farm management and environmental factors on preharvest spinach contamination with generic Escherichia coli as an indicator of fecal contamination. A repeated cross-sectional study was conducted by visiting spinach farms up to four times per growing season over a period of 2 years (2010 to 2011). Spinach samples (n = 955) were collected from 12 spinach farms in Colorado and Texas as representative states of the Western and Southwestern United States, respectively. During each farm visit, farmers were surveyed about farm-related management and environmental factors using a questionnaire. Associations between the prevalence of generic E. coli in spinach and farm-related factors were assessed by using a multivariable logistic regression model including random effects for farm and farm visit. Overall, 6.6% of spinach samples were positive for generic E. coli. Significant risk factors for spinach contamination with generic E. coli were the proximity (within 10 miles) of a poultry farm, the use of pond water for irrigation, a >66-day period since the planting of spinach, farming on fields previously used for grazing, the production of hay before spinach planting, and the farm location in the Southwestern United States. Contamination with generic E. coli was significantly reduced with an irrigation lapse time of >5 days as well as by several factors related to field workers, including the use of portable toilets, training to use portable toilets, and the use of hand-washing stations. To our knowledge, this is the first report of an association between field workers' personal hygiene and produce contamination with generic E. coli at the preharvest level. Collectively, our findings support that practice of good personal hygiene and other good farm management practices may reduce produce contamination with generic E. coli at the preharvest level.

Generic Escherichia coli Contamination of Spinach at the Preharvest Stage: Effects of Farm Management and Environmental Factors

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Navratil, Sarah; Gregory, Ashley; Bauer, Arin; Srinath, Indumathi; Jun, Mikyoung; Szonyi, Barbara; Nightingale, Kendra; Anciso, Juan; Ivanek, Renata

2013-01-01

The objective of this study was to determine the effects of farm management and environmental factors on preharvest spinach contamination with generic Escherichia coli as an indicator of fecal contamination. A repeated cross-sectional study was conducted by visiting spinach farms up to four times per growing season over a period of 2 years (2010 to 2011). Spinach samples (n = 955) were collected from 12 spinach farms in Colorado and Texas as representative states of the Western and Southwestern United States, respectively. During each farm visit, farmers were surveyed about farm-related management and environmental factors using a questionnaire. Associations between the prevalence of generic E. coli in spinach and farm-related factors were assessed by using a multivariable logistic regression model including random effects for farm and farm visit. Overall, 6.6% of spinach samples were positive for generic E. coli. Significant risk factors for spinach contamination with generic E. coli were the proximity (within 10 miles) of a poultry farm, the use of pond water for irrigation, a >66-day period since the planting of spinach, farming on fields previously used for grazing, the production of hay before spinach planting, and the farm location in the Southwestern United States. Contamination with generic E. coli was significantly reduced with an irrigation lapse time of >5 days as well as by several factors related to field workers, including the use of portable toilets, training to use portable toilets, and the use of hand-washing stations. To our knowledge, this is the first report of an association between field workers' personal hygiene and produce contamination with generic E. coli at the preharvest level. Collectively, our findings support that practice of good personal hygiene and other good farm management practices may reduce produce contamination with generic E. coli at the preharvest level. PMID:23666336

The tRNA synthetase paralog PoxA modifies elongation factor-P with (R)-ß-lysine

DEFF Research Database (Denmark)

Roy, Hervé; Zou, S Betty; Bullwinkle, Tammy J

2011-01-01

The lysyl-tRNA synthetase paralog PoxA modifies elongation factor P (EF-P) with a-lysine at low efficiency. Cell-free extracts containing non-a-lysine substrates of PoxA modified EF-P with a change in mass consistent with addition of ß-lysine, a substrate also predicted by genomic analyses. EF......-P was efficiently functionally modified with (R)-ß-lysine but not (S)-ß-lysine or genetically encoded a-amino acids, indicating that PoxA has evolved an activity orthogonal to that of the canonical aminoacyl-tRNA synthetases....

Risk factors for extended-spectrum b-lactamases-producing Escherichia coli urinary tract infections in a tertiary hospital

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María Dolores Alcántar-Curiel

2015-09-01

Full Text Available Objective. To assess the risks factors for urinary tract infections (UTIs caused by Extended-Spectrum Beta-Lactamases (ESBLs-producing E. coli and the molecular characterization of ESBLs. Materials and methods. A case-control study was performed to identify risk factors in consecutively recruited patients with UTIs caused by ESBLs or non-ESBLs-producing E. coli in a tertiary hospital in Mexico. Results. ESBLs-producing E. coli were isolated from 22/70 (31% patients with E. coli UTIs over a three month period. All isolates were resistant to cephalosporins and quinolones but susceptible to carbapenems, amikacin and nitrofurantoin. Prior antibiotic treatment with more than two antibiotic families (OR=6.86; 95%CI 1.06-157.70; p=0.028, recurrent symptomatic UTIs (OR=5.60; 95%CI 1.88-17.87; p=0.001 and previous hospitalization (OR=5.06; 95%CI 1.64-17.69;p=0.002 were significant risk factors. Sixteen isolates harbored the beta-lactamase (blaCTX-M-15 gene and five the blaTEM-1 gene. Conclusions. One of every three patients presented UTIs with ESBLs-producing beta-lactams and fluoroquinolone resistant E. coli. Risk factors and resistance patterns must be taken into account for developing antibiotic use policies in these settings

Data regarding the growth of Lactobacillus acidophilus NCFM on different carbohydrates and recombinant production of elongation factor G and pyruvate kinase

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Celebioglu, Hasan Ufuk; Olesen, Sita Vaag; Prehn, Kennie

2017-01-01

The present study describes the growth of the very well-known probiotic bacterium Lactobacillus acidophilus NCFM on different carbohydrates. Furthermore, recombinant production of putative moonlighting proteins elongation factor G and pyruvate kinase from this bacterium is described. For further...

Heterochromatin protein 1 gamma and IκB kinase alpha interdependence during tumour necrosis factor gene transcription elongation in activated macrophages.

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Thorne, James L; Ouboussad, Lylia; Lefevre, Pascal F

2012-09-01

IκB kinase α (IKKα) is part of the cytoplasmic IKK complex regulating nuclear factor-κB (NF-κB) release and translocation into the nucleus in response to pro-inflammatory signals. IKKα can also be recruited directly to the promoter of NF-κB-dependent genes by NF-κB where it phosphorylates histone H3 at serine 10, triggering recruitment of the bromodomain-containing protein 4 and the positive transcription elongation factor b. Herein, we report that IKKα travels with the elongating form of ribonucleic acid polymerase II together with heterochromatin protein 1 gamma (HP1γ) at NF-κB-dependent genes in activated macrophages. IKKα binds to and phosphorylates HP1γ, which in turn controls IKKα binding to chromatin and phosphorylation of the histone variant H3.3 at serine 31 within transcribing regions. Downstream of transcription end sites, IKKα accumulates with its inhibitor the CUE-domain containing protein 2, suggesting a link between IKKα inactivation and transcription termination.

Elongation of exogenous fatty acids by the bioluminescent bacterium Vibrio harveyi

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Byers, D.M.

1989-01-01

Bioluminescent bacteria require myristic acid (C14:0) to produce the myristaldehyde substrate of the light-emitting luciferase reaction. Since both endogenous and exogenous C14:0 can be used for this purpose, the metabolism of exogenous fatty acids by luminescent bacteria has been investigated. Both Vibrio harveyi and Vibrio fischeri incorporated label from (1-14C)myristic acid (C14:0) into phospholipid acyl chains as well as into CO2. In contrast, Photobacterium phosphoreum did not exhibit phospholipid acylation or beta-oxidation using exogenous fatty acids. Unlike Escherichia coli, the two Vibrio species can directly elongate fatty acids such as octanoic (C8:0), lauric (C12:0), and myristic acid, as demonstrated by radio-gas liquid chromatography. The induction of bioluminescence in late exponential growth had little effect on the ability of V. harveyi to elongate fatty acids, but it did increase the amount of C14:0 relative to C16:0 labeled from (14C)C8:0. This was not observed in a dark mutant of V. harveyi that is incapable of supplying endogenous C14:0 for luminescence. Cerulenin preferentially decreased the labeling of C16:0 and of unsaturated fatty acids from all 14C-labeled fatty acid precursors as well as from (14C)acetate, suggesting that common mechanisms may be involved in elongation of fatty acids from endogenous and exogenous sources. Fatty acylation of the luminescence-related synthetase and reductase enzymes responsible for aldehyde synthesis exhibited a chain-length preference for C14:0, which also was indicated by reverse-phase thin-layer chromatography of the acyl groups attached to these enzymes. The ability of V. harveyi to activate and elongate exogenous fatty acids may be related to an adaptive requirement to metabolize intracellular C14:0 generated by the luciferase reaction during luminescence development.

Elongation of exogenous fatty acids by the bioluminescent bacterium Vibrio harveyi

International Nuclear Information System (INIS)

Byers, D.M.

1989-01-01

Bioluminescent bacteria require myristic acid (C14:0) to produce the myristaldehyde substrate of the light-emitting luciferase reaction. Since both endogenous and exogenous C14:0 can be used for this purpose, the metabolism of exogenous fatty acids by luminescent bacteria has been investigated. Both Vibrio harveyi and Vibrio fischeri incorporated label from [1-14C]myristic acid (C14:0) into phospholipid acyl chains as well as into CO2. In contrast, Photobacterium phosphoreum did not exhibit phospholipid acylation or beta-oxidation using exogenous fatty acids. Unlike Escherichia coli, the two Vibrio species can directly elongate fatty acids such as octanoic (C8:0), lauric (C12:0), and myristic acid, as demonstrated by radio-gas liquid chromatography. The induction of bioluminescence in late exponential growth had little effect on the ability of V. harveyi to elongate fatty acids, but it did increase the amount of C14:0 relative to C16:0 labeled from [14C]C8:0. This was not observed in a dark mutant of V. harveyi that is incapable of supplying endogenous C14:0 for luminescence. Cerulenin preferentially decreased the labeling of C16:0 and of unsaturated fatty acids from all 14C-labeled fatty acid precursors as well as from [14C]acetate, suggesting that common mechanisms may be involved in elongation of fatty acids from endogenous and exogenous sources. Fatty acylation of the luminescence-related synthetase and reductase enzymes responsible for aldehyde synthesis exhibited a chain-length preference for C14:0, which also was indicated by reverse-phase thin-layer chromatography of the acyl groups attached to these enzymes. The ability of V. harveyi to activate and elongate exogenous fatty acids may be related to an adaptive requirement to metabolize intracellular C14:0 generated by the luciferase reaction during luminescence development

Agent-based modeling of oxygen-responsive transcription factors in Escherichia coli.

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Hao Bai

2014-04-01

Full Text Available In the presence of oxygen (O2 the model bacterium Escherichia coli is able to conserve energy by aerobic respiration. Two major terminal oxidases are involved in this process - Cyo has a relatively low affinity for O2 but is able to pump protons and hence is energetically efficient; Cyd has a high affinity for O2 but does not pump protons. When E. coli encounters environments with different O2 availabilities, the expression of the genes encoding the alternative terminal oxidases, the cydAB and cyoABCDE operons, are regulated by two O2-responsive transcription factors, ArcA (an indirect O2 sensor and FNR (a direct O2 sensor. It has been suggested that O2-consumption by the terminal oxidases located at the cytoplasmic membrane significantly affects the activities of ArcA and FNR in the bacterial nucleoid. In this study, an agent-based modeling approach has been taken to spatially simulate the uptake and consumption of O2 by E. coli and the consequent modulation of ArcA and FNR activities based on experimental data obtained from highly controlled chemostat cultures. The molecules of O2, transcription factors and terminal oxidases are treated as individual agents and their behaviors and interactions are imitated in a simulated 3-D E. coli cell. The model implies that there are two barriers that dampen the response of FNR to O2, i.e. consumption of O2 at the membrane by the terminal oxidases and reaction of O2 with cytoplasmic FNR. Analysis of FNR variants suggested that the monomer-dimer transition is the key step in FNR-mediated repression of gene expression.

The Caenorhabditis elegans Elongator complex regulates neuronal alpha-tubulin acetylation.

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Jachen A Solinger

2010-01-01

Full Text Available Although acetylated alpha-tubulin is known to be a marker of stable microtubules in neurons, precise factors that regulate alpha-tubulin acetylation are, to date, largely unknown. Therefore, a genetic screen was employed in the nematode Caenorhabditis elegans that identified the Elongator complex as a possible regulator of alpha-tubulin acetylation. Detailed characterization of mutant animals revealed that the acetyltransferase activity of the Elongator is indeed required for correct acetylation of microtubules and for neuronal development. Moreover, the velocity of vesicles on microtubules was affected by mutations in Elongator. Elongator mutants also displayed defects in neurotransmitter levels. Furthermore, acetylation of alpha-tubulin was shown to act as a novel signal for the fine-tuning of microtubules dynamics by modulating alpha-tubulin turnover, which in turn affected neuronal shape. Given that mutations in the acetyltransferase subunit of the Elongator (Elp3 and in a scaffold subunit (Elp1 have previously been linked to human neurodegenerative diseases, namely Amyotrophic Lateral Sclerosis and Familial Dysautonomia respectively highlights the importance of this work and offers new insights to understand their etiology.

Regulation of eukaryotic elongation factor 1 alpha (eEF1A) by dynamic lysine methylation

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Jakobsson, Magnus E; Małecki, Jędrzej; Falnes, Pål Ø

2018-01-01

Lysine methylation is a frequent post-translational protein modification, which has been intensively studied in the case of histone proteins. Lysine methylations are also found on many non-histone proteins, and one prominent example is eukaryotic elongation factor 1 alpha (eEF1A). Besides its...... essential role in the protein synthesis machinery, a number of non-canonical functions have also been described for eEF1A, such as regulation of the actin cytoskeleton and the promotion of viral replication. The functional significance of the extensive lysine methylations on eEF1A, as well as the identity...

Impaired rate of microsomal fatty acid elongation in undernourished neonatal rat brain

International Nuclear Information System (INIS)

Yeh, Y.Y.

1986-01-01

Hypomyelination caused by undernourishment in characterized by low concentrations of myelin lipids and marked reduction in lignocerate (C/sub 24:0/) and nervonate (C/sub 24:1/) moiety of cerebroside and sulfatide. Since microsomal elongation is the major source of long chain (22 to 24 carbons) fatty acids in the brain, the effect of neonatal undernourishment on acyl elongation was investigated. Undernourishment of suckling rats were induced after birth by restricting maternal dietary intake to 40% of that consumed by dams fed ad libitum. Neonates suckled by the normally fed dams served as controls. Microsomal elongation was measured as nmol from [2- 14 C] malonyl CoA incorporated/h per mg of protein. At 19 days of age, rates of behenoyl CoA (C/sub 22:0/) and erucoyl CoA (C/sub 22:1/) elongation in whole brain of undernourished neonates were 30-40% lower than that of the control, whereas the elongation rates of acyl CoA 16, 18 and 20 carbons in length either saturated or monounsaturated were similar in both groups. Undernourishment had no effect on cytoplasmic de novo fatty acid synthesis from acetyl CoA. If there are multiple elongation factors, the results indicate that the depressed activity of elongating enzyme(s) for C/sub 22:0/ and C/sub 22:1/ is an important contributing factor in lowering S/sub 24:0/ and C/sub 24:1/ content in cerebroside and sulfatide. This impairment may be a specific lesion leading to hypomyelination in undernourished rats

Non-Escherichia coli versus Escherichia coli community-acquired urinary tract infections in children hospitalized in a tertiary center: relative frequency, risk factors, antimicrobial resistance and outcome.

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Marcus, Nir; Ashkenazi, Shai; Yaari, Arnon; Samra, Zmira; Livni, Gilat

2005-07-01

Currently hospitalization for children with urinary tract infections (UTIs) is reserved for severe or complicated cases. Changes may have taken place in the characteristics and causative uropathogens of hospital-treated community-acquired UTI. To study children hospitalized in a tertiary center with community-acquired UTI, compare Escherichia coli and non-E. coli UTI, define predictors for non-E. coli UTI and elucidate the appropriate therapeutic approach. A prospective clinical and laboratory study from 2001 through 2002 in a tertiary pediatric medical center. Patients were divided by results of the urine culture into E. coli and non-E. coli UTI groups, which were compared. Of 175 episodes of culture-proved UTI, 70 (40%) were caused by non-E. coli pathogens. Non-E. coli UTI was more commonly found in children who were male (P = 0.005), who had underlying renal abnormalities (P = 0.0085) and who had received antibiotic therapy in the prior month (P = 0.0009). Non-E. coli uropathogens were often resistant to antibiotics usually recommended for initial therapy for UTI, including cephalosporins and aminoglycosides; 19% were initially treated with inappropriate empiric intravenous antibiotics (compared with 2% for E. coli UTI, P = 0.0001), with a longer hospitalization. Current treatment routines are often inappropriate for hospitalized children with non-E. coli UTI, which is relatively common in this population. The defined risk factors associated with non-E. coli UTIs and its antimicrobial resistance patterns should be considered to improve empiric antibiotic therapy for these infections.

Nearshore hydrodynamics as loading and forcing factors for Escherichia coli contamination at an embayed beach

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Ge, Zhongfu; Whitman, Richard L.; Nevers, Meredith B.; Phanikumar, Mantha S.; Byappanahalli, Muruleedhara N.

2012-01-01

Numerical simulations of the transport and fate of Escherichia coli were conducted at Chicago's 63rd Street Beach, an embayed beach that had the highest mean E. coli concentration among 23 similar Lake Michigan beaches during summer months of 2000-2005, in order to find the cause for the high bacterial contamination. The numerical model was based on the transport of E. coli by current circulation patterns in the embayment driven by longshore main currents and the loss of E. coli in the water column, taking settling as well as bacterial dark- and solar-related decay into account. Two E. coli loading scenarios were considered: one from the open boundary north of the embayment and the other from the shallow water near the beachfront. Simulations showed that the embayed beach behaves as a sink for E. coli in that it generally receives E. coli more efficiently than it releases them. This is a result of the significantly different hydrodynamic forcing factors between the inside of the embayment and the main coastal flow outside. The settled E. coli inside the embayment can be a potential source of contamination during subsequent sediment resuspension events, suggesting that deposition-resuspension cycles of E. coli have resulted in excessive bacterial contamination of beach water. A further hypothetical case with a breakwater shortened to half its original length, which was anticipated to enhance the current circulation in the embayment, showed a reduction in E. coli concentrations of nearly 20%.

Factors affecting Escherichia coli concentrations at Lake Erie public bathing beaches

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Francy, Donna S.; Darner, Robert A.

1998-01-01

The environmental and water-quality factors that affect concentrations of Escherichia coli (E. coli) in water and sediment were investigated at three public bathing beachesEdgewater Park, Villa Angela, and Sims Parkin the Cleveland, Ohio metropolitan area. This study was done to aid in the determination of safe recreational use and to help water- resource managers assess more quickly and accurately the degradation of recreational water quality. Water and lake-bottom sediments were collected and ancillary environmental data were compiled for 41 days from May through September 1997. Water samples were analyzed for E. coli concentrations, suspended sediment concentrations, and turbidity. Lake- bottom sediment samples from the beach area were analyzed for E. coli concentrations and percent dry weight. Concentrations of E. coli were higher and more variable at Sims Park than at Villa Angela or Edgewater Park; concentrations were lowest at Edgewater Park. Time-series plots showed that short-term storage (less than one week) of E. coli in lake-bottom sediments may have occurred, although no evidence for long-term storage was found during the sampling period. E. coli concentrations in water were found to increase with increasing wave height, but the resuspension of E. coli from lake-bottom sediments by wave action could not be adequately assessed; higherwave heights were often associated with the discharge of sewage containing E. coli during or after a rainfall and wastewater-treatment plant overflow. Multiple linear regression (MLR) was used to develop models to predict recreational water quality at the in water. The related variables included turbidity, antecedent rainfall, antecedent weighted rainfall, volumes of wastewater-treatment plant overflows and metered outfalls (composed of storm-water runoff and combined-sewer overflows), a resuspension index, and wave heights. For the beaches in this study, wind speed, wind direction, water temperature, and the prswimmers

Conjugation in Escherichia coli

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Boyer, Herbert

1966-01-01

Boyer, Herbert (Yale University, New Haven, Conn.). Conjugation in Escherichia coli. J. Bacteriol. 91:1767–1772. 1966.—The sex factor of Escherichia coli K-12 was introduced into an E. coli B/r strain by circumventing the host-controlled modification and restriction incompatibilities known to exist between these closely related strains. The sexual properties of the constructed F+ B strain and its Hfr derivatives were examined. These studies showed that the E. coli strain B/r F+ and Hfr derivatives are similar to the E. coli strain K-12 F+ and Hfr derivatives. However, the site of sex factor integration was found to be dependent on the host genome. PMID:5327905

Simultaneous Binding of Multiple EF-Tu Copies to Translating Ribosomes in Live Escherichia coli.

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Mustafi, Mainak; Weisshaar, James C

2018-01-16

In bacteria, elongation factor Tu is a translational cofactor that forms ternary complexes with aminoacyl-tRNA (aa-tRNA) and GTP. Binding of a ternary complex to one of four flexible L7/L12 units on the ribosome tethers a charged tRNA in close proximity to the ribosomal A site. Two sequential tests for a match between the aa-tRNA anticodon and the current mRNA codon then follow. Because one elongation cycle can occur in as little as 50 ms and the vast majority of aa-tRNA copies are not cognate with the current mRNA codon, this testing must occur rapidly. We present a single-molecule localization and tracking study of fluorescently labeled EF-Tu in live Escherichia coli Imaging at 2 ms/frame distinguishes 60% slowly diffusing EF-Tu copies (assigned as transiently bound to translating ribosome) from 40% rapidly diffusing copies (assigned as a mixture of free ternary complexes and free EF-Tu). Combining these percentages with copy number estimates, we infer that the four L7/L12 sites are essentially saturated with ternary complexes in vivo. The results corroborate an earlier inference that all four sites can simultaneously tether ternary complexes near the A site, creating a high local concentration that may greatly enhance the rate of testing of aa-tRNAs. Our data and a combinatorial argument both suggest that the initial recognition test for a codon-anticodon match occurs in less than 1 to 2 ms per aa-tRNA copy. The results refute a recent study (A. Plochowietz, I. Farrell, Z. Smilansky, B. S. Cooperman, and A. N. Kapanidis, Nucleic Acids Res 45:926-937, 2016, https://doi.org/10.1093/nar/gkw787) of tRNA diffusion in E. coli that inferred that aa-tRNAs arrive at the ribosomal A site as bare monomers, not as ternary complexes. IMPORTANCE Ribosomes catalyze translation of the mRNA codon sequence into the corresponding sequence of amino acids within the nascent polypeptide chain. Polypeptide elongation can be as fast as 50 ms per added amino acid. Each amino acid

Human Meningitis-Associated Escherichia coli

Science.gov (United States)

KIM, KWANG SIK

2016-01-01

E. coli is the most common Gram-negative bacillary organism causing meningitis and E. coli meningitis continues to be an important cause of mortality and morbidity throughout the world. Our incomplete knowledge of its pathogenesis contributes to such mortality and morbidity. Recent reports of E. coli strains producing CTX-M-type or TEM-type extended-spectrum β-lactamases create a challenge. Studies using in vitro and in vivo models of the blood-brain barrier have shown that E. coli meningitis follows a high-degree of bacteremia and invasion of the blood-brain barrier. E. coli invasion of the blood-brain barrier, the essentials step in the development of E. coli meningitis, requires specific microbial and host factors as well as microbe- and host-specific signaling molecules. Blockade of such microbial and host factors contributing to E. coli invasion of the blood-brain barrier is shown to be efficient in preventing E. coli penetration into the brain. The basis for requiring a high-degree of bacteremia for E. coli penetration of the blood-brain barrier, however, remains unclear. Continued investigation on the microbial and host factors contributing to a high-degree of bacteremia and E. coli invasion of the blood-brain barrier is likely to identify new targets for prevention and therapy of E. coli meningitis. PMID:27223820

Comparison of Antibiotic Resistance and Virulence Factors among Escherichia coli Isolated from Conventional and Free-Range Poultry

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Vanessa L. Koga

2015-01-01

Full Text Available Microbiological contamination in commercial poultry production has caused concerns for human health because of both the presence of pathogenic microorganisms and the increase in antimicrobial resistance in bacterial strains that can cause treatment failure of human infections. The aim of our study was to analyze the profile of antimicrobial resistance and virulence factors of E. coli isolates from chicken carcasses obtained from different farming systems (conventional and free-range poultry. A total of 156 E. coli strains were isolated and characterized for genes encoding virulence factors described in extraintestinal pathogenic E. coli (ExPEC. Antimicrobial susceptibility testing was performed for 15 antimicrobials, and strains were confirmed as extended spectrum of β-lactamases- (ESBLs- producing E. coli by phenotypic and genotypic tests. The results indicated that strains from free-range poultry have fewer virulence factors than strains from conventional poultry. Strains from conventionally raised chickens had a higher frequency of antimicrobial resistance for all antibiotics tested and also exhibited genes encoding ESBL and AmpC, unlike free-range poultry isolates, which did not. Group 2 CTX-M and CIT were the most prevalent ESBL and AmpC genes, respectively. The farming systems of poultries can be related with the frequency of virulence factors and resistance to antimicrobials in bacteria.

Critical Factors Affecting the Success of Cloning, Expression, and Mass Production of Enzymes by Recombinant E. coli.

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Fakruddin, Md; Mohammad Mazumdar, Reaz; Bin Mannan, Khanjada Shahnewaj; Chowdhury, Abhijit; Hossain, Md Nur

2013-01-01

E. coli is the most frequently used host for production of enzymes and other proteins by recombinant DNA technology. E. coli is preferable for its relative simplicity, inexpensive and fast high-density cultivation, well-known genetics, and large number of compatible molecular tools available. Despite all these advantages, expression and production of recombinant enzymes are not always successful and often result in insoluble and nonfunctional proteins. There are many factors that affect the success of cloning, expression, and mass production of enzymes by recombinant E. coli. In this paper, these critical factors and approaches to overcome these obstacles are summarized focusing controlled expression of target protein/enzyme in an unmodified form at industrial level.

A Herpesviral Immediate Early Protein Promotes Transcription Elongation of Viral Transcripts

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Hannah L. Fox

2017-06-01

Full Text Available Herpes simplex virus 1 (HSV-1 genes are transcribed by cellular RNA polymerase II (RNA Pol II. While four viral immediate early proteins (ICP4, ICP0, ICP27, and ICP22 function in some capacity in viral transcription, the mechanism by which ICP22 functions remains unclear. We observed that the FACT complex (comprised of SSRP1 and Spt16 was relocalized in infected cells as a function of ICP22. ICP22 was also required for the association of FACT and the transcription elongation factors SPT5 and SPT6 with viral genomes. We further demonstrated that the FACT complex interacts with ICP22 throughout infection. We therefore hypothesized that ICP22 recruits cellular transcription elongation factors to viral genomes for efficient transcription elongation of viral genes. We reevaluated the phenotype of an ICP22 mutant virus by determining the abundance of all viral mRNAs throughout infection by transcriptome sequencing (RNA-seq. The accumulation of almost all viral mRNAs late in infection was reduced compared to the wild type, regardless of kinetic class. Using chromatin immunoprecipitation sequencing (ChIP-seq, we mapped the location of RNA Pol II on viral genes and found that RNA Pol II levels on the bodies of viral genes were reduced in the ICP22 mutant compared to wild-type virus. In contrast, the association of RNA Pol II with transcription start sites in the mutant was not reduced. Taken together, our results indicate that ICP22 plays a role in recruiting elongation factors like the FACT complex to the HSV-1 genome to allow for efficient viral transcription elongation late in viral infection and ultimately infectious virion production.

Risk factors for indigenous Campylobacter jejuni and Campylobacter coli infections in The Netherlands: a case-control study

NARCIS (Netherlands)

Doorduyn, Y.; Brandhof, van den W.E.; Duynhoven, van Y.T.H.P.; Breukink, B.J.; Wagenaar, J.A.; Pelt, van W.

2010-01-01

A case-control study comprising 1315 Campylobacter jejuni cases, 121 Campylobacter coli cases and 3409 frequency-matched controls was conducted in The Netherlands in 2002-2003. Risk factors for both C. jejuni and C. coli enteritis were consumption of undercooked meat and barbecued meat, ownership of

Factors associated with post-treatment E. coli contamination in households practising water treatment: a study of rural Cambodia.

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Benwic, Aaron; Kim, Erin; Khema, Cinn; Phanna, Chet; Sophary, Phan; Cantwell, Raymond E

2018-04-01

The purpose of this study was to assess factors associated with Escherichia coli (E. coli) contamination in rural households in Cambodia that have adopted household water treatment. The following factors were significantly associated (α E. coli contamination: cleaning the drinking vessel with untreated water, not drying the cup (with a cloth), accessing treated water by the use of a scoop (ref: using a tap), having more than one untreated water storage container, having an untreated water storage container that appeared dirty on the outside, and cows living within 10 m of the household. This study provides further evidence confirming previous studies reporting an association between inadequate cleanliness of water storage containers and household drinking water contamination, and identifies practical recommendations statistically associated with reduced post-treatment E. coli contamination in the household setting in rural Cambodia.

[Lactobacillus rhamnosus GG conditioned medium prevents E. coli meningitis by inhibiting nuclear factor-κB pathway].

Science.gov (United States)

Zeng, Qing; He, Xiao-Long; Xiao, Han-Sheng; DU, Lei; Li, Yu-Jing; Chen, Le-Cheng; Tian, Hui-Wen; Huang, Sheng-He; Cao, Hong

2017-01-20

To investigate whether Lactobacillus rhamnosus GG conditioned medium(LGG-CM)has preventive effect against E. coli K1-induced neuropathogenicity in vitro by inhibiting nuclear factor-κB (NF-κB) signaling pathway. An in vitro blood-brain barrier (BBB) model was constructed using human brain microvascular endothelial cells (HBMECs). The effect of LGG-CM on E. coli-actived NF-κB signaling pathway was assayed using Western blotting. Invasion assay and polymorphonuclear leukocyte (PMN) transmigration assay were performed to explore whether LGG-CM could inhibit E. coli invasion and PMN transmigration across the BBB in vitro. The expressions of ZO-1 and CD44 were detected using Western blotting and immunofluorescence. The changes of trans-epithelial electric resistance (TEER) and bacterial translocation were determined to evaluate the BBB permeability. Pre-treament with LGG-CM inhibited E. coli-activated NF-κB signaling pathway in HBMECs and decreased the invasion of E. coli K1 and transmigration of PMN. Western blotting showed that LGG-CM could alleviate E. coli-induced up-regulation of CD44 and down-regulation of ZO-1 expressions in HBMECs. In addition, pre-treatment with LGG-CM alleviated E. coli K1-induced reduction of TEER and suppressed bacterial translocation across the BBB in vitro. LGG-CM can block E. coli-induced activation of NF-κB signaling pathway and thereby prevents E. coli K1-induced neuropathogenicity by decreasing E. coli K1 invasion rates and PMN transmigration.

Colocalization and interaction between elongasome and divisome during a preparative cell division phase in Escherichia coli

NARCIS (Netherlands)

Ploeg, van der R.; Verheul, J.; Vischer, N.O.E.; Alexeeva, S.V.; Hoogendoorn, E.; Postma, M.; Banzhaf, M.; Vollmer, W.; Blaauwen, den T.

2013-01-01

The rod-shaped bacterium Escherichia coli grows by insertion of peptidoglycan into the lateral wall during cell elongation and synthesis of new poles during cell division. The monofunctional transpeptidases PBP2 and PBP3 are part of specialized protein complexes called elongasome and divisome,

Epidemiological factors associated with ESBL- and non ESBL-producing E. coli causing urinary tract infection in general practice

DEFF Research Database (Denmark)

Hertz, Frederik Boetius; Schønning, Kristian; Rasmussen, Steen Christian

2016-01-01

were prospectively collected and retrospective statistical analyses were done. This study included 98 cases with urinary tract infection (UTI) caused by ESBL-producing E. coli, 174 with antibiotic-resistant (non-ESBL) E. coli, 177 with susceptible E. coli and 200 with culture negative urine samples....... Case groups had significantly higher use of antibiotics than the control group within 30 days before infection (p UTI by ESBL......-producing E. coli. Exposure to antibiotics was a risk factor for UTI with E. coli, while prior antibiotic usage was not an indisputable predictor for infection with ESBL-producing E.coli in general practice....

Epidemiological factors associated with ESBL- and non ESBL-producing E. coli causing urinary tract infection in general practice.

Science.gov (United States)

Hertz, Frederik Boëtius; Schønning, Kristian; Rasmussen, Steen Christian; Littauer, Pia; Knudsen, Jenny Dahl; Løbner-Olesen, Anders; Frimodt-Møller, Niels

2016-01-01

The purpose of the study was to evaluate how use of antibiotics precedes the presence of ESBL-producing E.coli in general practice. The authors performed a triple-case-control study where three case groups were individually compared to a single control group of uninfected individuals. Urine samples were prospectively collected and retrospective statistical analyses were done. This study included 98 cases with urinary tract infection (UTI) caused by ESBL-producing E. coli, 174 with antibiotic-resistant (non-ESBL) E. coli, 177 with susceptible E. coli and 200 with culture negative urine samples. Case groups had significantly higher use of antibiotics than the control group within 30 days before infection (p E. coli. Exposure to antibiotics was a risk factor for UTI with E. coli, while prior antibiotic usage was not an indisputable predictor for infection with ESBL-producing E.coli in general practice.

Response of Escherichia coli to Prolonged Berberine Exposure.

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Budeyri Gokgoz, Nilay; Avci, Fatma Gizem; Yoneten, Kubra Karaosmanoglu; Alaybeyoglu, Begum; Ozkirimli, Elif; Sayar, Nihat Alpagu; Kazan, Dilek; Sariyar Akbulut, Berna

2017-07-01

Berberine is a plant-derived alkaloid possessing antimicrobial activity; unfortunately, its efflux through multidrug resistance pumps reduces its efficacy. Cellular life span of Escherichia coli is generally shorter with prolonged berberine exposure; nevertheless, about 30% of the cells still remain robust following this treatment. To elucidate its mechanism of action and to identify proteins that could be involved in development of antimicrobial resistance, protein profiles of E. coli cells treated with berberine for 4.5 and 8 hours were compared with control cells. A total of 42 proteins were differentially expressed in cells treated with berberine for 8 hours when compared to control cells. In both 4.5 and 8 hours of berberine-treated cells, carbohydrate and peptide uptake regimens remained unchanged, although amino acid maintenance regimen switched from transport to synthesis. Defect in cell division persisted and this condition was confirmed by images obtained from scanning electron microscopy. Universal stress proteins were not involved in stress response. The significant increase in the abundance of elongation factors could suggest the involvement of these proteins in protection by exhibiting chaperone activities. Furthermore, the involvement of the outer membrane protein OmpW could receive special attention as a protein involved in response to antimicrobial agents, since the expression of only this porin protein was upregulated after 8 hours of exposure.

Ribosome slowed by mutation to streptomycin resistance. [Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

Galas, D J; Branscomb, E W

1976-08-12

The effect of mutation to streptomycin resistance on the speed of polypeptide elongation in Escherichia coli was investigated. Translation speed was determined by measuring the time required for the first newly synthesized ..beta..-galactosidase molecules to appear after induction of the lactose operon. The results showed that ribosome speed is not a fixed parameter inherent to the protein synthetic apparatus, but a variable determined by the kinetics of translation and ultimately by the structure of the ribosome. (HLW)

Escherichia coli Contamination across Multiple Environmental Compartments (Soil, Hands, Drinking Water, and Handwashing Water) in Urban Harare: Correlations and Risk Factors.

Science.gov (United States)

Navab-Daneshmand, Tala; Friedrich, Max N D; Gächter, Marja; Montealegre, Maria Camila; Mlambo, Linn S; Nhiwatiwa, Tamuka; Mosler, Hans-Joachim; Julian, Timothy R

2018-03-01

Escherichia coli pathotypes (i.e., enteropathogenic and enterotoxigenic) have been identified among the pathogens most responsible for moderate-to-severe diarrhea in low- and middle-income countries (LMICs). Pathogenic E. coli are transmitted from infected human or animal feces to new susceptible hosts via environmental reservoirs such as hands, water, and soil. Commensal E. coli , which includes nonpathogenic E. coli strains, are widely used as fecal bacteria indicator, with their presence associated with increased likelihood of enteric pathogens and/or diarrheal disease. In this study, we investigated E. coli contamination in environmental reservoirs within households ( N = 142) in high-population density communities of Harare, Zimbabwe. We further assessed the interconnectedness of the environmental compartments by investigating associations between, and household-level risk factors for, E. coli contamination. From the data we collected, the source and risk factors for E. coli contamination are not readily apparent. One notable exception is the presence of running tap water on the household plot, which is associated with significantly less E. coli contamination of drinking water, handwashing water, and hands after handwashing. In addition, E. coli levels on hands after washing are significantly associated with handwashing water contamination, hand contamination before washing, and diarrhea incidence. Finally, we observed that animal ownership increases E. coli contamination in soil, and E. coli in soil are correlated with contamination on hands before washing. This study highlights the complexity of E. coli contamination in household environments within LMICs. More, larger, studies are needed to better identify sources and exposure pathways of E. coli -and enteric pathogens generally-to identify effective interventions.

Elongational viscosity of narrow molar mass distribution polystyrene

DEFF Research Database (Denmark)

Bach, Anders; Almdal, Kristoffer; Rasmussen, Henrik Koblitz

2003-01-01

Transient and steady elongational viscosity has been measured for two narrow molar mass distribution polystyrene melts of molar masses 200 000 and 390 000 by means of a filament stretching rheometer. Total Hencky strains of about five have been obtained. The transient elongational viscosity rises...... above the linear viscoelastic prediction at intermediate strains, indicating strain hardening. The steady elongational viscosities are monotone decreasing functions of elongation rate. At elongation rates larger than the inverse reptation time, the steady elongational viscosity scales linearly...

Mutations in a plastid-localized elongation factor G alter early stages of plastid development in Arabidopsis thaliana

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Hangarter Roger P

2007-07-01

Full Text Available Abstract Background Proper development of plastids in embryo and seedling tissues is critical for plant development. During germination, plastids develop to perform many critical functions that are necessary to establish the seedling for further growth. A growing body of work has demonstrated that components of the plastid transcription and translation machinery must be present and functional to establish the organelle upon germination. Results We have identified Arabidopsis thaliana mutants in a gene that encodes a plastid-targeted elongation factor G (SCO1 that is essential for plastid development during embryogenesis since two T-DNA insertion mutations in the coding sequence (sco1-2 and sco1-3 result in an embryo-lethal phenotype. In addition, a point mutation allele (sco1-1 and an allele with a T-DNA insertion in the promoter (sco1-4 of SCO1 display conditional seedling-lethal phenotypes. Seedlings of these alleles exhibit cotyledon and hypocotyl albinism due to improper chloroplast development, and normally die shortly after germination. However, when germinated on media supplemented with sucrose, the mutant plants can produce photosynthetically-active green leaves from the apical meristem. Conclusion The developmental stage-specific phenotype of the conditional-lethal sco1 alleles reveals differences in chloroplast formation during seedling germination compared to chloroplast differentiation in cells derived from the shoot apical meristem. Our identification of embryo-lethal mutant alleles in the Arabidopsis elongation factor G indicates that SCO1 is essential for plant growth, consistent with its predicted role in chloroplast protein translation.

Clustered, regularly interspaced short palindromic repeat (CRISPR) diversity and virulence factor distribution in avian Escherichia coli.

Science.gov (United States)

Fu, Qiang; Su, Zhixin; Cheng, Yuqiang; Wang, Zhaofei; Li, Shiyu; Wang, Heng'an; Sun, Jianhe; Yan, Yaxian

In order to investigate the diverse characteristics of clustered, regularly interspaced short palindromic repeat (CRISPR) arrays and the distribution of virulence factor genes in avian Escherichia coli, 80 E. coli isolates obtained from chickens with avian pathogenic E. coli (APEC) or avian fecal commensal E. coli (AFEC) were identified. Using the multiplex polymerase chain reaction (PCR), five genes were subjected to phylogenetic typing and examined for CRISPR arrays to study genetic relatedness among the strains. The strains were further analyzed for CRISPR loci and virulence factor genes to determine a possible association between their CRISPR elements and their potential virulence. The strains were divided into five phylogenetic groups: A, B1, B2, D and E. It was confirmed that two types of CRISPR arrays, CRISPR1 and CRISPR2, which contain up to 246 distinct spacers, were amplified in most of the strains. Further classification of the isolates was achieved by sorting them into nine CRISPR clusters based on their spacer profiles, which indicates a candidate typing method for E. coli. Several significant differences in invasion-associated gene distribution were found between the APEC isolates and the AFEC isolates. Our results identified the distribution of 11 virulence genes and CRISPR diversity in 80 strains. It was demonstrated that, with the exception of iucD and aslA, there was no sharp demarcation in the gene distribution between the pathogenic (APEC) and commensal (AFEC) strains, while the total number of indicated CRISPR spacers may have a positive correlation with the potential pathogenicity of the E. coli isolates. Copyright © 2016. Published by Elsevier Masson SAS.

Risk Factors for the Development of Gastrointestinal Colonization With Fluoroquinolone-Resistant Escherichia coli in Residents of Long-Term Care Facilities

Science.gov (United States)

Han, Jennifer H.; Maslow, Joel; Han, Xiaoyan; Xie, Sharon X.; Tolomeo, Pam; Santana, Evelyn; Carson, Lesley; Lautenbach, Ebbing

2014-01-01

Background. The objective of this study was to assess risk factors for the development of fluoroquinolone (FQ)–resistant Escherichia coli gastrointestinal tract colonization in long-term care facility (LTCF) residents. Methods. A prospective cohort study was conducted from 2006 to 2008 at 3 LTCFs. Residents initially colonized with FQ-susceptible E. coli were followed by means of serial fecal sampling for new FQ-resistant E. coli colonization for up to 12 months or until discharge or death. A Cox proportional hazards regression model was developed to identify risk factors for new FQ-resistant E. coli colonization, with antibiotic and device exposures modeled as time-varying covariates. Results. Fifty-seven (47.5%) of 120 residents became newly colonized with FQ-resistant E. coli, with a median time to colonization of 57 days. Fecal incontinence (hazard ratio [HR], 1.78; 95% confidence interval [CI], 1.04–3.06; P = .04) was significantly associated with FQ-resistant E. coli acquisition. Receipt of amoxicillin-clavulanate (HR, 6.48; 95% CI, 1.43–29.4; P = .02) and the presence of a urinary catheter (HR, 3.81; 95% CI, 1.06–13.8; P = .04) during LTCF stay increased the risk of new FQ-resistant E. coli colonization. Conclusions. Acquisition of FQ-resistant E. coli was common, with nearly half of LTCF residents developing new FQ-resistant E. coli colonization. Further studies are needed on interventions to limit the emergence of FQ-resistant E. coli in LTCFs. PMID:23986544

Genetic Transfer of Salmonella typhimurium and Escherichia coli Lipopolysaccharide Antigens to Escherichia coli K-12

Science.gov (United States)

Jones, Randall T.; Koeltzow, Donald E.; Stocker, B. A. D.

1972-01-01

Escherichia coli K-12 ϰ971 was crossed with a smooth Salmonella typhimurium donor, HfrK6, which transfers early the ilv-linked rfa region determining lipopolysaccharide (LPS) core structure. Two ilv+ hybrids differing in their response to the LPS-specific phages FO and C21 were then crossed with S. typhimurium HfrK9, which transfers early the rfb gene cluster determining O repeat unit structure. Most recombinants selected for his+ (near rfb) were agglutinated by Salmonella factor 4 antiserum. Transfer of an F′ factor (FS400) carrying the rfb–his region of S. typhimurium to the same two ilv+ hybrids gave similar results. LPS extracted from two ilv+,his+, factor 4-positive hybrids contained abequose, the immunodominant sugar for factor 4 specificity. By contrast, his+ hybrids obtained from ϰ971 itself by similar HfrK9 and F′FS400 crosses were not agglutinated by factor 4 antiserum, indicating that the parental E. coli ϰ971 does not have the capacity to attach Salmonella O repeat units to its LPS core. It is concluded that the Salmonella rfb genes are expressed only in E. coli ϰ971 hybrids which have also acquired ilv-linked genes (presumably rfa genes affecting core structure or O-translocase ability, or both) from a S. typhimurium donor. When E. coli ϰ971 was crossed with a smooth E. coli donor, Hfr59, of serotype O8, which transfers his early, most his+ recombinants were agglutinated by E. coli O8 antiserum and lysed by the O8-specific phage, Ω8. This suggests that, although the parental E. coli K-12 strain ϰ971 cannot attach Salmonella-specific repeat units to its LPS core, it does have the capacity to attach E. coli O8-specific repeat units. PMID:4559827

Simplified Method to Produce Human Bioactive Leukemia Inhibitory Factor in Escherichia coli

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Houman Kahroba

2016-07-01

Full Text Available Background Human leukemia inhibitory factor (hLIF is a poly functional cytokine with numerous regulatory effects on different cells. Main application of hLIF is maintaining pluripotency of embryonic stem cells. hLIF indicated effective work in implantation rate of fertilized eggs and multiple sclerosis (MS treatment. Low production of hLIF in eukaryotic cells and prokaryotic host’s problems for human protein production convinced us to develop a simple way to reach high amount of this widely used clinical and research factor. Objectives In this study we want to purify recombinant human leukemia inhibitory factor in single simple method. Materials and Methods This is an experimental study, gene expression: human LIF gene was codon optimized for expression in Escherichia coli and attached his-tag tail to make it extractable. After construction and transformation of vector to E. coli, isopropyl β-D-1-thiogalactopyranoside (IPTG used for induction. Single step immobilized metal affinity chromatography (IMAC used for purification confirmed by Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE and western blotting. Bioactivity of the hLIF were tested by MTT assay with TF-1 cells and CISH gene stimulation in monocyte and TF-1 by real-time PCR. Induction by 0.4 mM of IPTG in 25°C for 3 hours indicated best result for soluble expression. SPSS indicated P ˂ 0.05 that is significant for our work. Results Cloning, expression, and extraction of bio active rhLIF was successfully achieved according MTT assay and real time PCR after treatment of TF-1 and monocyte cell lines. Conclusions We developed an effective single step purification method to produce bioactive recombinant hLIF in E. coli. For the first time we used CISH gene stimulating for bioactivity test for qualifying of recombinant hLIF for application.

Elongational viscosity of multiarm (Pom-Pom) polystyrene

DEFF Research Database (Denmark)

Nielsen, Jens Kromann; Rasmussen, Henrik K.; Almdal, Kristoffer

2006-01-01

-Pom was estimated to have 2.5 arms on average, while the estimate is 3.3 for the asymmetric star. The molar mass of each arm is about 27 kg/mol. The melts were characterized in the linear viscoelastic regime and in non-linear elongational rheometry. The transient elongational viscosity for the Pom-Pom molecule...... it corresponds well with an estimate of the maximum stretchability of the backbone. Time-strain separability was not observed for the 'Asymmetric star' molecule at the elongation rates investigated. The transient elongational viscosity for the 'Pom-Pom' molecule went through a reproducible maximum...... in the viscosity at the highest elongational rate....

Up-regulation of intestinal vascular endothelial growth factor by Afa/Dr diffusely adhering Escherichia coli.

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Gaëlle Cane

Full Text Available BACKGROUND: Angiogenesis has been recently described as a novel component of inflammatory bowel disease pathogenesis. The level of vascular endothelial growth factor (VEGF has been found increased in Crohn's disease and ulcerative colitis mucosa. To question whether a pro-inflammatory Escherichia coli could regulate the expression of VEGF in human intestinal epithelial cells, we examine the response of cultured human colonic T84 cells to infection by E. coli strain C1845 that belongs to the typical Afa/Dr diffusely adhering E. coli family (Afa/Dr DAEC. METHODOLOGY: VEGF mRNA expression was examined by Northern blotting and q-PCR. VEGF protein levels were assayed by ELISA and its bioactivity was analysed in endothelial cells. The bacterial factor involved in VEGF induction was identified using recombinant E. coli expressing Dr adhesin, purified Dr adhesin and lipopolysaccharide. The signaling pathway activated for the up-regulation of VEGF was identified using a blocking monoclonal anti-DAF antibody, Western blot analysis and specific pharmacological inhibitors. PRINCIPAL FINDINGS: C1845 bacteria induce the production of VEGF protein which is bioactive. VEGF is induced by adhering C1845 in both a time- and bacteria concentration-dependent manner. This phenomenon is not cell line dependent since we reproduced this observation in intestinal LS174, Caco2/TC7 and INT407 cells. Up-regulation of VEGF production requires: (1 the interaction of the bacterial F1845 adhesin with the brush border-associated decay accelerating factor (DAF, CD55 acting as a bacterial receptor, and (2 the activation of a Src protein kinase upstream of the activation of the Erk and Akt signaling pathways. CONCLUSIONS: Results demonstrate that a Afa/Dr DAEC strain induces an adhesin-dependent activation of DAF signaling that leads to the up-regulation of bioactive VEGF in cultured human intestinal cells. Thus, these results suggest a link between an entero-adherent, pro

Characterization of novel peptide-specific antibodies against the translation elongation factor eEF1A2 and their application for cancer research

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Shalak V. F.

2014-11-01

Full Text Available Aim. We intend to characterize the new peptide-specific antibodies against the isoform 2 of translation elongation factor 1A (eEF1A2 and determine its presence in the postoperative samples of human breast, lung and stomach tumor tissues. Methods. The analysis of antibody specificity was performed by enzyme-linked immunosorbent assay, immunoblotting and immunohistochemistry. Immunoblotting and immunohistochemistry were used for the determination of the eEF1A2 in the human tumor samples, as well as in the samples of normal tissues surrounding tumors. Results. The antibodies obtained against the eEF1A2 specifically recognized this protein in the cell extracts and histological sections and did not cross-react with the elongation factor 1A isoform 1. eEF1A2 was revealed in the postoperative samples of breast, lung and stomach tumors as well as in the putative normal tissues surrounding tumors. Conclusions. The antibodies obtained against eEF1A2 are highly specific for the antigen and can be used for the immunological studies of tumors.

It's fun to transcribe with Fun30: A model for nucleosome dynamics during RNA polymerase II-mediated elongation.

Science.gov (United States)

Lee, Junwoo; Choi, Eun Shik; Lee, Daeyoup

2018-01-01

The ability of elongating RNA polymerase II (RNAPII) to regulate the nucleosome barrier is poorly understood because we do not know enough about the involved factors and we lack a conceptual framework to model this process. Our group recently identified the conserved Fun30/SMARCAD1 family chromatin-remodeling factor, Fun30 Fft3 , as being critical for relieving the nucleosome barrier during RNAPII-mediated elongation, and proposed a model illustrating how Fun30 Fft3 may contribute to nucleosome disassembly during RNAPII-mediated elongation. Here, we present a model that describes nucleosome dynamics during RNAPII-mediated elongation in mathematical terms and addresses the involvement of Fun30 Fft3 in this process.

Carbon nanoparticles in lateral flow methods to detect genes encoding virulence factors of Shiga toxin-producing Escherichia coli

NARCIS (Netherlands)

Noguera, P.; Posthuma-Trumpie, G.A.; Tuil, van M.; Wal, van der F.J.; Boer, de A.; Moers, A.P.H.A.; Amerongen, van A.

2011-01-01

The use of carbon nanoparticles is shown for the detection and identification of different Shiga toxin-producing Escherichia coli virulence factors (vt1, vt2, eae and ehxA) and a 16S control (specific for E. coli) based on the use of lateral flow strips (nucleic acid lateral flow immunoassay,

Risk factors for fecal colonization with multiple distinct strains of Escherichia coli among long-term care facility residents.

Science.gov (United States)

Lautenbach, Ebbing; Tolomeo, Pam; Black, Nicole; Maslow, Joel N

2009-05-01

Of 49 long-term care facility residents, 21 (43%) were colonized with 2 or more distinct strains of Escherichia coli. There were no significant risk factors for colonization with multiple strains of E. coli. These results suggest that future efforts to efficiently identify the diversity of colonizing strains will be challenging.

Volunteer Challenge With Enterotoxigenic Escherichia coli That Express Intestinal Colonization Factor Fimbriae CS17 and CS19

Science.gov (United States)

2011-07-01

Serotype was determined by classic serological methods at the Universidad Nacional Aut6noma de Mexico [UNAMl. H- indrcates non-motility. b CF...Levine MM, Merson MM. Serologic differentiation between antitoxin responses to infection with Vibrio cholerae and enterotoxin-producing Escherichia coli...prototype cholera B subunit-colonization factor antigen cnterotoxigenic Escherichia coli vaccine. Vaccine 1993; 1[:929-34. 15. Levine MM, Nalin DR

Sedimentation and gravitational instability of Escherichia coli Suspension

Science.gov (United States)

Salin, Dominique; Douarche, Carine

2017-11-01

The successive runs and tumbles of Escherichia coli bacteria provide an active matter suspension of rod-like particles with a large swimming, Brownian like, diffusion. As opposed to inactive elongated particles, this diffusion prevents clustering of the particles and hence instability in the gravity field. We measure the time dependent E . coli concentration profile during their sedimentation. After some hours, due to the dioxygen consumption, a motile / non-motile front forms leading to a Rayleigh-Taylor type gravitational instability. Analysing both sedimentation and instability in the framework of active particle suspensions, we can measure the relevant bacteria hydrodynamic characteristics such as its single particle sedimentation velocity and its hindrance volume. Comparing these quantities to the ones of equivalent passive particles (ellipsoid, rod) we tentatively infer the effective shape and size of the bacteria involved in its buoyancy induced advection and diffusion. Laboratoire FAST University Paris Saclay France.

Amphiregulin Antibody and Reduction of Axial Elongation in Experimental Myopia

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Wen Jun Jiang

2017-03-01

Full Text Available To examine the mechanism of ocular axial elongation in myopia, guinea pigs (age: 2–3 weeks which either underwent unilateral or bilateral lens-induced myopization (group 1 or which were primarily myopic at baseline (group 2 received unilateral intraocular injections of amphiregulin antibody (doses: 5, 10, or 15 μg three times in intervals of 9 days. A third group of emmetropic guinea pigs got intraocular unilateral injections of amphiregulin (doses: 0.25, 0.50 or 1.00 ng, respectively. In each group, the contralateral eyes received intraocular injections of Ringer's solution. In intra-animal inter-eye comparison and intra-eye follow-up comparison in groups 1 and 2, the study eyes as compared to the contralateral eyes showed a dose-dependent reduction in axial elongation. In group 3, study eyes and control eyes did not differ significantly in axial elongation. Immunohistochemistry revealed amphiregulin labelling at the retinal pigment epithelium in eyes with lens-induced myopization and Ringer's solution injection, but not in eyes with amphiregulin antibody injection. Intraocular injections of amphiregulin-antibody led to a reduction of lens-induced axial myopic elongation and of the physiological eye enlargement in young guinea pigs. In contrast, intraocularly injected amphiregulin in a dose of ≤1 ng did not show a significant effect. Amphiregulin may be one of several essential molecular factors for axial elongation.

Aphidicolin-induced nuclear elongation in tobacco BY-2 cells.

Science.gov (United States)

Yasuhara, Hiroki; Kitamoto, Kazuki

2014-05-01

Plant nuclei are known to differentiate into various shapes within a single plant. However, little is known about the mechanisms of nuclear morphogenesis. We found that nuclei of tobacco BY-2 cells were highly elongated on long-term treatment with 5 mg l⁻¹ aphidicolin, an inhibitor of DNA polymerase α. In aphidicolin-treated cells, the nuclear length was correlated with the cell length. During culture in the presence of aphidicolin, the nuclei were elongated in parallel with cell elongation. Nuclear elongation was inhibited by the inhibition of cell elongation with 2,6-dichlorobenzonitrile, a cellulose synthesis inhibitor. However, cell elongation induced in the auxin-depleted medium in the absence of aphidicolin did not cause nuclear elongation, indicating that cell elongation alone is not sufficient for nuclear elongation. Treatment with either latrunculin B or propyzamide inhibited the aphidicolin-induced nuclear elongation, indicating that both actin filaments and microtubules (MTs) are required for nuclear elongation. Observations using BY-YTHCLR2 cells, in which actin filaments, MTs and nuclei were simultaneously visualized, revealed that the longitudinally arranged MT bundles associated with the nucleus play an important role in nuclear elongation, and that actin filaments affect the formation of these MT bundles. In aphidicolin-treated cells, the nuclear DNA contents of the elongated nuclei exceeded 4C, and the nuclear length was highly correlated with the nuclear DNA content. In cells treated with 50 mg l⁻¹ aphidicolin, cells were elongated and nucleus-associated longitudinal MT bundles were formed, but the nuclear DNA contents did not exceed 4C and the nuclei did not elongate. These results indicate that an increase in the nuclear DNA content above 4C is also required for nuclear elongation.

The incidence and risk factors of resistant E. coli infections after prostate biopsy under fluoroquinolone prophylaxis: a single-centre experience with 2215 patients.

Science.gov (United States)

Kandemir, Özlem; Bozlu, Murat; Efesoy, Ozan; Güntekin, Onur; Tek, Mesut; Akbay, Erdem

2016-08-01

We evaluated the incidence and risk factors of resistant Escherichia coli infections after the prostate biopsy under flouroquinolone prophylaxis. From January 2003 to December 2012, we retrospectively evaluated the records of 2215 patients. The risk factors were described for infective complications and resistant E. coli in positive cultures was calculated. Of 2215 patients, 153 had positive urine cultures, such as 129 (84·3%) E. coli, 8 (5·2%) Enterococcus spp., 6 (3·9%) Enterobacter spp., 5 (3·2%) Pseudomonas spp., 3 (1·9%) MRCNS, and 2 (1·3%) Klebsiella spp. Of the positive urine cultures which yielded E. coli, 99 (76·7%) were evaluated for fluoroquinolone resistance. Of those, 83 (83·8%) were fluoroquinolone-resistant and composed of 51 (61·4%) extended-spectrum beta-lactamase (ESBL)-positive. Fluoroquinolone-resistant E. coli ratios were 73·4 and 95·9% before 2008 and after 2008, respectively (P = 0·002). The most sensitive antibiotics for fluoroquinolone-resistant E. coli strains were imipenem (100%), amikacin (84%) and cefoperazone (83%). The use of quinolones in the last 6 months and a history of hospitalization in the last 30 days were found to be significant risk factors. We found that resistant E. coli strains might be a common microorganism in patients with this kind of complication. The risk factors for development of infection with these resistant strains were history of the use of fluoroquinolones and hospitalization.

Sound propagation in elongated superfluid fermionic clouds

International Nuclear Information System (INIS)

Capuzzi, P.; Vignolo, P.; Federici, F.; Tosi, M. P.

2006-01-01

We use hydrodynamic equations to study sound propagation in a superfluid Fermi gas at zero temperature inside a strongly elongated cigar-shaped trap, with main attention to the transition from the BCS to the unitary regime. First, we treat the role of the radial density profile in the limit of a cylindrical geometry and then evaluate numerically the effect of the axial confinement in a configuration in which a hole is present in the gas density at the center of the trap. We find that in a strongly elongated trap the speed of sound in both the BCS and the unitary regime differs by a factor √(3/5) from that in a homogeneous three-dimensional superfluid. The predictions of the theory could be tested by measurements of sound-wave propagation in a setup such as that exploited by Andrews et al. [Phys. Rev. Lett. 79, 553 (1997)] for an atomic Bose-Einstein condensate

Plant cell wall polysaccharide analysis during cell elongation

DEFF Research Database (Denmark)

Guo, Xiaoyuan

Plant cell walls are complex structures whose composition and architecture are important to various cellular activities. Plant cell elongation requires a high level of rearrangement of the cell wall polymers to enable cell expansion. However, the cell wall polysaccharides dynamics during plant cell...... elongation is poorly understood. This PhD project aims to elucidate the cell wall compositional and structural change during cell elongation by using Comprehensive Microarray Polymer Profiling (CoMPP), microscopic techniques and molecular modifications of cell wall polysaccharide. Developing cotton fibre......, pea and Arabidopsis thaliana were selected as research models to investigate different types of cell elongation, developmental elongation and tropism elongation. A set of comprehensive analysis covering 4 cotton species and 11 time points suggests that non-cellulosic polysaccharides contribute...

Factors related to axial length elongation and myopia progression in orthokeratology practice.

Directory of Open Access Journals (Sweden)

Bingjie Wang

Full Text Available To investigate which baseline factors are predictive for axial length growth over an average period of 2.5 years in a group of children wearing orthokeratology (OK contact lenses.In this retrospective study, the clinical records of 249 new OK wearers between January 2012 and December 2013 from the contact lens clinic at the Eye and ENT Hospital of Fudan University were reviewed. The primary outcome measure was axial length change from baseline to the time of review (July-August 2015. Independent variables included baseline measures of age at initiation of OK wear, gender, refractive error (spherical equivalent, astigmatism, average keratometry, corneal toricity, central corneal thickness, white-to-white corneal diameter, pupil size, corneal topography eccentricity value (e-value, intraocular pressure (IOP and total time in follow-up (months total. The contributions of all independent variables on axial length change at the time of review were assessed using univariate and multivariable regression analyses.Univariate analyses of the right eyes of 249 OK patients showed that smaller increases in axial length were associated with older age at the onset of OK lens wear, greater baseline spherical equivalent myopic refractive error, less time in follow-up and a smaller e-value. Multivariable analyses of the significant right eye variables showed that the factors associated with smaller axial length growth were older age at the onset of OK lens wear (p<0.0001, greater baseline spherical equivalent myopic refractive error (p = 0.0046 and less time in follow-up (p<0.0001.The baseline factors demonstrating the greatest correlation with reduced axial length elongation during OK lens wear in myopic children included greater baseline spherical equivalent myopic refractive error and older age at the onset of OK lens wear.

Translational Control of Cell Division by Elongator

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Fanelie Bauer

2012-05-01

Full Text Available Elongator is required for the synthesis of the mcm5s2 modification found on tRNAs recognizing AA-ending codons. In order to obtain a global picture of the role of Elongator in translation, we used reverse protein arrays to screen the fission yeast proteome for translation defects. Unexpectedly, this revealed that Elongator inactivation mainly affected three specific functional groups including proteins implicated in cell division. The absence of Elongator results in a delay in mitosis onset and cytokinesis defects. We demonstrate that the kinase Cdr2, which is a central regulator of mitosis and cytokinesis, is under translational control by Elongator due to the Lysine codon usage bias of the cdr2 coding sequence. These findings uncover a mechanism by which the codon usage, coupled to tRNA modifications, fundamentally contributes to gene expression and cellular functions.

Cytolysin a expressing E. coli a promising candidate for imageable therapeutic probe

International Nuclear Information System (INIS)

Nguyen, Vu Hong; Phan, Thuy Xuan; Hong, Yeoung Jin; Min, Jung Joon

2007-01-01

Using bacteria for cancer treatment has a long history. Discovery of optical reporter genes consisting of fluorescent and luminescent protein facilitates the monitor of bacteria in vivo, non-invasively and repeatedly. E. coli, the natural enteric bacteria possessing capacity of tumor-targeting ability, seems to be suitable candidate for cancer treatment. In this study, we established the strain light-emitting E. coli for diagnostic purpose and Cytolysin A (Cly A) expressing E. coli for therapeutic purpose. E. coli (MG1655, wild type strain) was transformed plasmid pUC19 carrying lux gene to create the light expressing bacteria and test the tumor targeting-capacity by injecting the bacteria into CT26-tumor bearing mice via tail vein. On the other hand, for therapeutic purpose, plasmid containing Cly A gene, which is encoded for a pore-forming protein toxin, was introduced into E. coli. The toxicity of Cly A was evaluated in vitro by inoculating the bacteria with various cultured cancer cell lines. On the other hand, to test the therapeutic effect, the bacteria were injected intratumorally and intravenously into s.c.CT26-bearing as well as CT26-lung metastasized Balb/c mice. In vivo imaging data showed that the E. coli strains selectively located in the tumor. The in vitro result showed that the number of death cells were significantly higher in the samples containing E. coli expressing Cly A (E. coli Cly A) compared with the samples containing wild type strain. The growth of tumors was repressed in mice injected with either E. coli Cly A (significantly) or wild type E. coli (mildly), while tumors in no treatment group still grew fast. Furthermore, the tumors inoculated with E. coli cly A were necrotized but not with wild type E. coli. In the CT26-lung metastasized mouse model, the life span of mice was elongated when inject E. coli and longer in the group injected with E. coli cly A. Cly A expressing E. coli can become an effective candidate for imageable

Role of the ribosomal P-site elements of m²G966, m⁵C967, and the S9 C-terminal tail in maintenance of the reading frame during translational elongation in Escherichia coli.

Science.gov (United States)

Arora, Smriti; Bhamidimarri, Satya Prathyusha; Weber, Michael H W; Varshney, Umesh

2013-08-01

The ribosomal P-site hosts the peptidyl-tRNAs during translation elongation. Which P-site elements support these tRNA species to maintain codon-anticodon interactions has remained unclear. We investigated the effects of P-site features of methylations of G966, C967, and the conserved C-terminal tail sequence of Ser, Lys, and Arg (SKR) of the S9 ribosomal protein in maintenance of the translational reading frame of an mRNA. We generated Escherichia coli strains deleted for the SKR sequence in S9 ribosomal protein, RsmB (which methylates C967), and RsmD (which methylates G966) and used them to translate LacZ from its +1 and -1 out-of-frame constructs. We show that the S9 SKR tail prevents both the +1 and -1 frameshifts and plays a general role in holding the P-site tRNA/peptidyl-tRNA in place. In contrast, the G966 and C967 methylations did not make a direct contribution to the maintenance of the translational frame of an mRNA. However, deletion of rsmB in the S9Δ3 background caused significantly increased -1 frameshifting at 37°C. Interestingly, the effects of the deficiency of C967 methylation were annulled when the E. coli strain was grown at 30°C, supporting its context-dependent role.

Critical Factors Affecting the Success of Cloning, Expression, and Mass Production of Enzymes by Recombinant E. coli

OpenAIRE

Fakruddin, Md.; Mohammad Mazumdar, Reaz; Bin Mannan, Khanjada Shahnewaj; Chowdhury, Abhijit; Hossain, Md. Nur

2013-01-01

E. coli is the most frequently used host for production of enzymes and other proteins by recombinant DNA technology. E. coli is preferable for its relative simplicity, inexpensive and fast high-density cultivation, well-known genetics, and large number of compatible molecular tools available. Despite all these advantages, expression and production of recombinant enzymes are not always successful and often result in insoluble and nonfunctional proteins. There are many factors that affect the s...

Trade studies of plasma elongation for next-step tokamaks

International Nuclear Information System (INIS)

Galambos, J.D.; Strickler, D.J.; Peng, Y.K.M.; Reid, R.L.

1988-09-01

The effect of elongation on minimum-cost devices is investigated for elongations ranging from 2 to 3. The analysis, carried out with the TETRA tokamak systems code, includes the effects of elongation on both physics (plasma beta limit) and engineering (poloidal field coil currents) issues. When ignition is required, the minimum cost occurs for elongations from 2.3 to 2.9, depending on the plasma energy confinement scaling used. Scalings that include favorable plasma current dependence and/or degradation with fusion power tend to have minimum cost at higher elongation (2.5-2.9); scalings that depend primarily on size result in lower elongation (/approximately/2.3) for minimum cost. For design concepts that include steady-state current-driven operation, minimum cost occurs at an elongation of 2.3. 12 refs., 13 figs

Occurrence, genotyping, shiga toxin genes and associated risk factors of E. coli isolated from dairy farms, handlers and milk consumers.

Science.gov (United States)

Awadallah, M A; Ahmed, H A; Merwad, A M; Selim, M A

2016-11-01

The objectives of the current study were to determine the occurrence and genotypes of E. coli in dairy farms, workers and milk consumers and to evaluate risk factors associated with contamination of milk in dairy farms. Molecular characterization of shiga toxin associated genes and enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) finger printing of E. coli from different sources were also studied. Paired milk samples and rectal swabs from 125 dairy cows, rectal swabs from 82 calves and hand swabs from 45 dairy workers from five dairy farms were collected. In addition, 100 stool samples from 70 diarrheic and 30 healthy humans were collected and examined for the presence of E. coli. E. coli was isolated from milk (22.4%), dairy cattle feces (33.6%), calf feces (35.4%), dairy worker hand swabs (11.1%) and stools of milk consumers (2%, from diarrheic patients only). Only stx1 was identified in seven of 12 E. coli O125 isolated from different sources. High genetic diversity was determined (Simpson's index of diversity, D = 1) and E. coli O125 isolates were classified into 12 distinct profiles, E1-E12. The dendrogram analysis showed that two main clusters were generated. Mastitis in dairy cows was considered a risk factor associated with contamination of the produced milk with E. coli. The isolation of E. coli from rectal swabs of dairy cows and calves poses a zoonotic risk through consumption of unpasteurized contaminated dairy milk. Educational awareness should be developed to address risks related to consumption of raw milk. Copyright © 2016 Elsevier Ltd. All rights reserved.

Elongational viscosity of monodisperse and bidisperse polystyrene melts

DEFF Research Database (Denmark)

Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole

2006-01-01

The start-up and steady uniaxial elongational viscosity have been measured for two monodisperse polystyrene melts with molecular weights of 52 and 103 kg/mole, and for three bidisperse polystyrene melts. The monodisperse melts show a maximum in the steady elongational viscosity vs. the elongational...

Affinity isolation and I-DIRT mass spectrometric analysis of the Escherichia coli O157:H7 Sakai RNA polymerase complex.

Science.gov (United States)

Lee, David J; Busby, Stephen J W; Westblade, Lars F; Chait, Brian T

2008-02-01

Bacteria contain a single multisubunit RNA polymerase that is responsible for the synthesis of all RNA. Previous studies of the Escherichia coli K-12 laboratory strain identified a group of effector proteins that interact directly with RNA polymerase to modulate the efficiency of transcription initiation, elongation, or termination. Here we used a rapid affinity isolation technique to isolate RNA polymerase from the pathogenic Escherichia coli strain O157:H7 Sakai. We analyzed the RNA polymerase enzyme complex using mass spectrometry and identified associated proteins. Although E. coli O157:H7 Sakai contains more than 1,600 genes not present in the K-12 strain, many of which are predicted to be involved in transcription regulation, all of the identified proteins in this study were encoded on the "core" E. coli genome.

Immune Reactions Against Elongation Factor 2 Kinase: Specific Pathogenesis of Gastric Ulcer from Helicobacter pylori Infection

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Kiyoshi Ayada

2009-01-01

Full Text Available Helicobacter pylori (H. pylori infection is a definite causative factor for gastric ulcers (GUs. In the present study we detected a specific antigen of gastric epithelial cells (HGC-27 using cell ELISA, which was recognized by the sera of GU patients (n=20 but not in patients with chronic gastritis (CG; n=20 or in healthy volunteers (HC; n=10. This antigen was over-expressed by a stressful (heat-stressed environment, and was identified as elongation factor 2 kinase (EF-2K by western blotting. The GU patients' lymphocytes stimulated by H. pylori specifically disrupted heat-stressed HGC-27 cells in a cytotoxic assay. In flow cytometry, the effector cells (lymphocytes from GU patients were significantly differentiated to T helper type 1 lymphocyte (Th1 and cytotoxic T lymphocyte (CTL as opposed to those from CG patients. The target cells (HGC-27 expressed EF-2K and MHC-class I together with costimulatory molecules from heat stress. This antigen specific immune mechanism could have a prominent role in the pathogenesis of GU.

Visualization of elongation measurements using an SER universal testing platform

Czech Academy of Sciences Publication Activity Database

Pivokonský, Radek; Filip, Petr; Zelenková, Jana

2015-01-01

Roč. 25, č. 1 (2015), s. 1-8 ISSN 1430-6395 R&D Projects: GA ČR(CZ) GAP105/11/2342 Institutional support: RVO:67985874 Keywords : elongational viscosity * Universal Testing Platform (SER) * polymer melts * LDPE Subject RIV: BK - Fluid Dynamics Impact factor: 1.241, year: 2015

Data regarding the growth of Lactobacillus acidophilus NCFM on different carbohydrates and recombinant production of elongation factor G and pyruvate kinase

Directory of Open Access Journals (Sweden)

Hasan Ufuk Celebioglu

2017-10-01

Full Text Available The present study describes the growth of the very well-known probiotic bacterium Lactobacillus acidophilus NCFM on different carbohydrates. Furthermore, recombinant production of putative moonlighting proteins elongation factor G and pyruvate kinase from this bacterium is described. For further and detailed interpretation of the data presented here, please see the research article “Mucin- and carbohydrate-stimulated adhesion and subproteome changes of the probiotic bacterium Lactobacillus acidophilus NCFM” (Celebioglu et al., 2017 [1].

Efficient cell-free expression with the endogenous E. Coli RNA polymerase and sigma factor 70

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Noireaux Vincent

2010-06-01

Full Text Available Abstract Background Escherichia coli cell-free expression systems use bacteriophage RNA polymerases, such as T7, to synthesize large amounts of recombinant proteins. These systems are used for many applications in biotechnology, such as proteomics. Recently, informational processes have been reconstituted in vitro with cell-free systems. These synthetic approaches, however, have been seriously limited by a lack of transcription modularity. The current available cell-free systems have been optimized to work with bacteriophage RNA polymerases, which put significant restrictions to engineer processes related to biological information. The development of efficient cell-free systems with broader transcription capabilities is required to study complex informational processes in vitro. Results In this work, an efficient cell-free expression system that uses the endogenous E. coli RNA polymerase only and sigma factor 70 for transcription was prepared. Approximately 0.75 mg/ml of Firefly luciferase and enhanced green fluorescent protein were produced in batch mode. A plasmid was optimized with different regulatory parts to increase the expression. In addition, a new eGFP was engineered that is more translatable in cell-free systems than the original eGFP. The protein production was characterized with three different adenosine triphosphate (ATP regeneration systems: creatine phosphate (CP, phosphoenolpyruvate (PEP, and 3-phosphoglyceric acid (3-PGA. The maximum protein production was obtained with 3-PGA. Preparation of the crude extract was streamlined to a simple routine procedure that takes 12 hours including cell culture. Conclusions Although it uses the endogenous E. coli transcription machinery, this cell-free system can produce active proteins in quantities comparable to bacteriophage systems. The E. coli transcription provides much more possibilities to engineer informational processes in vitro. Many E. coli promoters/operators specific to sigma

Engineering the growth pattern and cell morphology for enhanced PHB production by Escherichia coli.

Science.gov (United States)

Wu, Hong; Chen, Jinchun; Chen, Guo-Qiang

2016-12-01

E. coli JM109∆envC∆nlpD deleted with genes envC and nlpD responsible for degrading peptidoglycan (PG) led to long filamentous cell shapes. When cell fission ring location genes minC and minD of Escherichia coli were deleted, E. coli JM109∆minCD changed the cell growth pattern from binary division to multiple fissions. Bacterial morphology can be further engineered by overexpressing sulA gene resulting in inhibition on FtsZ, thus generating very long cellular filaments. By overexpressing sulA in E. coli JM109∆envC∆nlpD and E. coli JM109∆minCD harboring poly(3-hydroxybutyrate) (PHB) synthesis operon phbCAB encoded in plasmid pBHR68, respectively, both engineered cells became long filaments and accumulated more PHB compared with the wild-type. Under same shake flask growth conditions, E. coli JM109∆minCD (pBHR68) overexpressing sulA grown in multiple fission pattern accumulated approximately 70 % PHB in 9 g/L cell dry mass (CDM), which was significantly higher than E. coli JM109∆envC∆nlpD and the wild type, that produced 7.6 g/L and 8 g/L CDM containing 64 % and 51 % PHB, respectively. Results demonstrated that a combination of the new division pattern with elongated shape of E. coli improved PHB production. This provided a new vision on the enhanced production of inclusion bodies.

Adefarakan et al (11) 2.cdr

African Journals Online (AJOL)

Timothy Ademakinwa

The study reports isolation and identification of Escherichia coli from the ... Keywords: Escherichia coli, ram, goat, antibiotic, resistant gene, virulence factors .... 30 s, elongation at 72 C for 30 s and final extension o ..... Staphylococcus aureus.

Site of ADP-ribosylation and the RNA-binding site are situated in different domains of the elongation factor EF-2

International Nuclear Information System (INIS)

Davydova, E.K.

1987-01-01

One of the proteins participating in the process of elongation of polypeptide chains - elongation factor 2 (EF-2) - can be ADP-ribosylated at a unique amino acid residue - diphthamide. Since the ADP-ribosylation of EF-2 at dipthamide leads to a loss of affinity of the factor for RNA while the presence of RNA inhibits the ADP-ribosylation reaction, it seemed probable to the authors that diphthamide participated directly in the binding of EF-2 to DNA. The experiments presented in this article showed that this was not the case: diphthamide and the RNA-binding site are situated on different domains of EF-2. Thus, ADP-ribosylation of factor EF-2 in one domain leads to a loss of the ability to bind to RNA in the other. The authors investigated the mutual arrangement of diphthamide and the RNA-binding site on the EF-2 molecule by preparing a factor from rabbit reticulocytes and subjecting it to proteolytic digestion with elastase. The factor was incubated with elastase for 15 min at 37 0 C at an enzyme:substrate ratio of 1:100 in buffer solution containing 20 mM Tris-HCl, pH 7.6, 10 mM KCl, 1 mM MgCl 2 , and 2 mM dithiothreitol. The reaction was stopped by adding para-methylsulfonyl fluoride to 50 micro-M. The authors obtained a preparation as a result of proteolysis and applied it on a column with RNA-Sepharose and separated into two fractions: RNA-binding and without affinity for RNA. The initial preparation and its fractions were subjected to exhaustive ADP-ribosylation in the presence of diphtheria toxin and [U- 14 C] nicotinaide adenine dinucleotide ([ 14 C]NAD) (296 mCi/mmole). The samples were analyzed electrophoretically in a polyacrylamide gel gradient in the presence of sodium dodecyl sulfate. For the detection of [ 14 C] ADP-ribosylated components, the gels were dried and exposed with RM-V x-ray film

Transcriptional Elongation Factor Elongin A Regulates Retinoic Acid-Induced Gene Expression during Neuronal Differentiation

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Takashi Yasukawa

2012-11-01

Full Text Available Elongin A increases the rate of RNA polymerase II (pol II transcript elongation by suppressing transient pausing by the enzyme. Elongin A also acts as a component of a cullin-RING ligase that can target stalled pol II for ubiquitylation and proteasome-dependent degradation. It is not known whether these activities of Elongin A are functionally interdependent in vivo. Here, we demonstrate that Elongin A-deficient (Elongin A−/− embryos exhibit abnormalities in the formation of both cranial and spinal nerves and that Elongin A−/− embryonic stem cells (ESCs show a markedly decreased capacity to differentiate into neurons. Moreover, we identify Elongin A mutations that selectively inactivate one or the other of the aforementioned activities and show that mutants that retain the elongation stimulatory, but not pol II ubiquitylation, activity of Elongin A rescue neuronal differentiation and support retinoic acid-induced upregulation of a subset of neurogenesis-related genes in Elongin A−/− ESCs.

[Prevalence and risk factors for extended-spectrum β-lactamase-producing Escherichia coli causing community-onset urinary tract infections in Colombia].

Science.gov (United States)

Blanco, Victor M; Maya, Juan J; Correa, Adriana; Perenguez, Marcela; Muñoz, Juan S; Motoa, Gabriel; Pallares, Christian J; Rosso, Fernando; Matta, Lorena; Celis, Yamile; Garzon, Martha; Villegas, María V

2016-11-01

Urinary tract infections (UTI) are common in the community. However, information of resistant isolates in this context is limited in Latin America. This study aims to determine the prevalence and risk factors associated with community-onset UTI (CO-UTI) caused by extended-spectrum β-lactamase (ESBL)-Producing Escherichia coli in Colombia. A case-control study was conducted between August and December of 2011 in three Colombian tertiary-care institutions. All patients who were admitted to the Emergency Department with a probable diagnosis of CO-UTI were invited to participate. All participating patients were asked for a urine sample. ESBL confirmatory test, antibiotic susceptibility, and molecular epidemiology were performed in these E.coli isolates (Real Time-PCR for bla genes, repetitive element palindromic PCR [rep-PCR], multilocus sequence typing [MLST] and virulence factors by PCR). Clinical and epidemiological information was recorded, and a statistical analysis was performed. Of the 2124 recruited patients, 629 had a positive urine culture, 431 of which grew E.coli; 54 were positive for ESBL, of which 29 were CTX-M-15. The majority of ESBL isolates were susceptible to ertapenem, phosphomycin and amikacin. Complicated UTI was strongly associated with ESBL-producing E.coli infections (OR=3.89; 95%CI: 1.10-13.89; P=.03). CTX-M-15-producing E.coli showed 10 different pulsotypes, 65% were PT1 or PT4, and corresponded to ST131. Most of these isolates had 8 out of the 9 analysed virulence factors. E.coli harbouring bla CTX-M-15 associated with ST131 is still frequent in Colombia. The presence of complicated CO-UTI increases the risk of ESBL-producing E.coli, and must be taken into account in order to provide an adequate empirical therapy. Copyright © 2015 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Peptidoglycan Hydrolases of Escherichia coli

Science.gov (United States)

van Heijenoort, Jean

2011-01-01

Summary: The review summarizes the abundant information on the 35 identified peptidoglycan (PG) hydrolases of Escherichia coli classified into 12 distinct families, including mainly glycosidases, peptidases, and amidases. An attempt is also made to critically assess their functions in PG maturation, turnover, elongation, septation, and recycling as well as in cell autolysis. There is at least one hydrolytic activity for each bond linking PG components, and most hydrolase genes were identified. Few hydrolases appear to be individually essential. The crystal structures and reaction mechanisms of certain hydrolases having defined functions were investigated. However, our knowledge of the biochemical properties of most hydrolases still remains fragmentary, and that of their cellular functions remains elusive. Owing to redundancy, PG hydrolases far outnumber the enzymes of PG biosynthesis. The presence of the two sets of enzymes acting on the PG bonds raises the question of their functional correlations. It is difficult to understand why E. coli keeps such a large set of PG hydrolases. The subtle differences in substrate specificities between the isoenzymes of each family certainly reflect a variety of as-yet-unidentified physiological functions. Their study will be a far more difficult challenge than that of the steps of the PG biosynthesis pathway. PMID:22126997

Targeted silencing of elongation factor 2 kinase suppresses growth and sensitizes tumors to doxorubicin in an orthotopic model of breast cancer.

Directory of Open Access Journals (Sweden)

Ibrahim Tekedereli

Full Text Available Eukaryotic elongation factor 2 kinase (eEF-2K, through its phosphorylation of elongation factor 2 (eEF2, provides a mechanism by which cells can control the rate of the elongation phase of protein synthesis. The activity of eEF-2K is increased in rapidly proliferating malignant cells, is inhibited during mitosis, and may contribute to the promotion of autophagy in response to anti-cancer therapies. The purpose of this study was to examine the therapeutic potential of targeting eEF-2K in breast cancer tumors. Through the systemic administration of liposomal eEF-2K siRNA (twice a week, i.v. 150 µg/kg, the expression of eEF-2K was down-regulated in vivo in an orthotopic xenograft mouse model of a highly aggressive triple negative MDA-MB-231 tumor. This targeting resulted in a substantial decrease in eEF2 phosphorylation in the tumors, and led to the inhibition of tumor growth, the induction of apoptosis and the sensitization of tumors to the chemotherapy agent doxorubicin. eEF-2K down-modulation in vitro resulted in a decrease in the expression of c-Myc and cyclin D1 with a concomitant increase in the expression of p27(Kip1. A decrease in the basal activity of c-Src (phospho-Tyr-416, focal adhesion kinase (phospho-Tyr-397, and Akt (phospho-Ser-473 was also detected following eEF-2K down-regulation in MDA-MB-231 cells, as determined by Western blotting. Where tested, similar results were seen in ER-positive MCF-7 cells. These effects were also accompanied by a decrease in the observed invasive phenotype of the MDA-MB-231 cells. These data support the notion that the disruption of eEF-2K expression in breast cancer cells results in the down-regulation of signaling pathways affecting growth, survival and resistance and has potential as a therapeutic approach for the treatment of breast cancer.

Characterization of the domains of E. coli initiation factor IF2 responsible for recognition of the ribosome

DEFF Research Database (Denmark)

Manuel Palacios Moreno, Juan; Andersen, Lars Dyrskjøt; Egebjerg Kristensen, Janni

1999-01-01

We have studied the interactions between the ribosome and the domains of Escherichia coli translation initiation factor 2, using an in vitro ribosomal binding assay with wild-type forms, N- and C-terminal truncated forms of IF2 as well as isolated structural domains. A deletion mutant of the factor...

Protective effects of indigenous Escherichia coli against a pathogenic E. coli challenge strain in pigs.

Science.gov (United States)

Vahjen, W; Cuisiniere, T; Zentek, J

2017-10-13

To investigate the inhibitory effect of indigenous enterobacteria on pathogenic Escherichia coli, a challenge trial with postweaning pigs was conducted. A pathogenic E. coli strain was administered to all animals and their health was closely monitored thereafter. Faecal samples were taken from three healthy and three diarrhoeic animals. Samples were cultivated on MacConkey agar and isolates were subcultured. A soft agar overlay assay was used to determine the inhibitory activity of the isolates. A total of 1,173 enterobacterial isolates were screened for their ability to inhibit the E. coli challenge strain. Colony forming units of enterobacteria on MacConkey agar were not different between healthy and diarrhoeic animals in the original samples. Furthermore, numbers of isolates per animal were also not significantly different between healthy (482 isolates) and diarrhoeic animals (691 isolates). A total of 43 isolates (3.7%) with inhibitory activity against the pathogenic E. coli challenge strain were detected. All inhibitory isolates were identified as E. coli via MALDI-TOF. The isolates belonged to the phylotypes A, C and E. Many isolates (67.4%) were commensal E. coli without relevant porcine pathogenic factors, but toxin- and fimbrial genes (stx2e, fae, estIb, elt1a, fas, fan) were detected in 14 inhibitory isolates. Healthy animals showed significantly (P=0.003) more inhibitory isolates (36 of 482 isolates; 7.5%) than diseased animals (7 of 691 isolates; 1.0%). There were no significant correlations regarding phylotype or pathogenic factors between healthy and diseased animals. This study has shown that a small proportion of indigenous E. coli is able to inhibit in vitro growth of a pathogenic E. coli strain in pigs. Furthermore, healthy animals possess significantly more inhibitory E. coli strains than diarrhoeic animals. The inhibition of pathogenic E. coli by specific indigenous E. coli strains may be an underlying principle for the containment of pathogenic

Mapping the human translation elongation factor eEF1H complex using the yeast two-hybrid system

DEFF Research Database (Denmark)

Mansilla, Francisco; Friis, Irene; Jadidi, Mandana

2002-01-01

In eukaryotes, the eukaryotic translation elongation factor eEF1A responsible for transporting amino-acylated tRNA to the ribosome forms a higher-order complex, eEF1H, with its guanine-nucleotide-exchange factor eEF1B. In metazoans, eEF1B consists of three subunits: eEF1B alpha, eEF1B eta and eEF1B...... of in vitro experiments have been proposed for the macromolecular organization of the eEF1H complex. However, these models differ in various aspects. This might be due to the difficulties of handling, particularly the eEF1B beta and eEF1B gamma subunits in vitro. Here, the human eEF1H complex is for the first...... gamma:eEF1B beta, where the last was observed using a three-hybrid approach. Surprisingly, eEF1A2 showed no or only little affinity for the guanine-nucleotide-exchange factors. Truncated versions of the subunits of eEF1B were used to orientate these subunits within the resulting model. The model unit...

DNA Barcoding for Identification of "Candidatus Phytoplasmas" Using a Fragment of the Elongation Factor Tu Gene

DEFF Research Database (Denmark)

Makarova, Olga; Contaldo, Nicoletta; Paltrinieri, Samanta

2012-01-01

Background Phytoplasmas are bacterial phytopathogens responsible for significant losses in agricultural production worldwide. Several molecular markers are available for identification of groups or strains of phytoplasmas. However, they often cannot be used for identification of phytoplasmas from...... different groups simultaneously or are too long for routine diagnostics. DNA barcoding recently emerged as a convenient tool for species identification. Here, the development of a universal DNA barcode based on the elongation factor Tu (tuf) gene for phytoplasma identification is reported. Methodology....../Principal Findings We designed a new set of primers and amplified a 420–444 bp fragment of tuf from all 91 phytoplasmas strains tested (16S rRNA groups -I through -VII, -IX through -XII, -XV, and -XX). Comparison of NJ trees constructed from the tuf barcode and a 1.2 kbp fragment of the 16S ribosomal gene revealed...

Affinity Isolation and I-DIRT Mass Spectrometric Analysis of the Escherichia coli O157:H7 Sakai RNA Polymerase Complex▿

Science.gov (United States)

Lee, David J.; Busby, Stephen J. W.; Westblade, Lars F.; Chait, Brian T.

2008-01-01

Bacteria contain a single multisubunit RNA polymerase that is responsible for the synthesis of all RNA. Previous studies of the Escherichia coli K-12 laboratory strain identified a group of effector proteins that interact directly with RNA polymerase to modulate the efficiency of transcription initiation, elongation, or termination. Here we used a rapid affinity isolation technique to isolate RNA polymerase from the pathogenic Escherichia coli strain O157:H7 Sakai. We analyzed the RNA polymerase enzyme complex using mass spectrometry and identified associated proteins. Although E. coli O157:H7 Sakai contains more than 1,600 genes not present in the K-12 strain, many of which are predicted to be involved in transcription regulation, all of the identified proteins in this study were encoded on the “core” E. coli genome. PMID:18083804

An Interbacterial NAD(P)+ Glycohydrolase Toxin Requires Elongation Factor Tu for Delivery to Target Cells

Energy Technology Data Exchange (ETDEWEB)

Whitney, John C.; Quentin, Dennis; Sawai, Shin; LeRoux, Michele; Harding, Brittany N.; Ledvina, Hannah E.; Tran, Bao Q.; Robinson, Howard; Goo, Young Ah; Goodlett, David R.; Raunser, Stefan; Mougous, Joseph D.

2015-10-08

Type VI secretion (T6S) influences the composition of microbial communities by catalyzing the delivery of toxins between adjacent bacterial cells. Here, we demonstrate that a T6S integral membrane toxin from Pseudomonas aeruginosa, Tse6, acts on target cells by degrading the universally essential dinucleotides NAD⁺ and NADP⁺. Structural analyses of Tse6 show that it resembles mono-ADP-ribosyltransferase proteins, such as diphtheria toxin, with the exception of a unique loop that both excludes proteinaceous ADP-ribose acceptors and contributes to hydrolysis. We find that entry of Tse6 into target cells requires its binding to an essential housekeeping protein, translation elongation factor Tu (EF-Tu). These proteins participate in a larger assembly that additionally directs toxin export and provides chaperone activity. Visualization of this complex by electron microscopy defines the architecture of a toxin-loaded T6S apparatus and provides mechanistic insight into intercellular membrane protein delivery between bacteria.

ATFL elongation after Brostrom procedure: a biomechanical investigation.

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Kirk, Kevin L; Campbell, John T; Guyton, Gregory P; Parks, Brent G; Schon, Lew C

2008-11-01

Elongation of ligaments during early mobilization after reconstruction may be associated with decreased stability. We evaluated elongation of the anterior talofibular ligament (ATFL) before and after lateral ligament reconstruction within a physiologic range of motion with protected and unprotected, isolated dorsiflexion/plantarflexion range of motion. Six fresh frozen cadaver legs were used with the ATFL meticulously dissected. A differential variable reluctance transducer (DVRT) was spaced to span the course of the ATFL using consistent placement points based on previous reports. Elongation was measured in a load frame with protected motion of 30 degrees plantarflexion and 10 degrees dorsiflexion for the intact and sectioned ATFL and for the repaired specimen with and without protected motion. The proximal DVRT anchor point was detached for sectioning and repair of the ATFL and replaced at the same position. Testing was 1000 cycles at 1 Hz for the repaired protected specimen and 10 cycles at 1 Hz for all other stages. Initial elongation in the unprotected, repaired group was significantly higher than initial elongation in the intact (p ankle after lateral ankle ligament reconstruction was not associated with elongation of the ATFL. The ATFL elongated significantly by comparison without protected dorsiflexion/plantarflexion. The study provides biomechanical support for the safety of early protected dorsiflexion/plantarflexion range of motion after Broström reconstruction.

Identification of genes involved in the ACC-mediated control of root cell elongation in Arabidopsis thaliana

Directory of Open Access Journals (Sweden)

Markakis Marios

2012-11-01

signaling cascade, these are converged to a ’common pathway’. Furthermore, several potential keyplayers, such as transcription factors and auxin-responsive genes, were identified by the microarray analysis. They await further analysis to reveal their exact role in the control of cell elongation.

Frequency and risk-factors analysis of Escherichia coli O157:H7 in Bali-cattle.

Science.gov (United States)

Suardana, I Wayan; Widiasih, Dyah Ayu; Nugroho, Widagdo Sri; Wibowo, Michael Haryadi; Suyasa, I Nyoman

2017-08-01

Cattle are known as the main reservoir of zoonotic agents verocytotoxin-producing Escherichia coli. These bacteria are usually isolated from calves with diarrhea and/or mucus and blood. Tolerance of these agents to the environmental conditions will strengthen of their transmission among livestock. A total of 238 cattle fecal samples from four sub-districts in Badung, Bali were used in this study. Epidemiological data observed include cattle age, sex, cattle rearing system, the source of drinking water, weather, altitude, and type of cage floor, the cleanliness of cage floor, the slope of cage floor, and the level of cattle cleanliness. The study was initiated by culturing of samples onto eosin methylene blue agar, then Gram stained, and tested for indole, methyl-red, voges proskauer, and citrate, Potential E.coli isolates were then cultured onto sorbitol MacConkey agar, and further tested using O157 latex agglutination test and H7 antisera. Molecular identification was performed by analysis of the 16S rRNA gene, and epidemiological data was analyzed using STATA 12.0 software. The results showed, the prevalence of E. coli O157:H7 in cattle at Badung regency was 6.30% (15/238) covering four sub districts i.e. Petang, Abiansemal, Mengwi, and Kuta which their prevalence was 8.62%(5/58), 10%(6/60), 3.33%(2/60), and 3.33(2/60)%, respectively. The analysis of 16S rRNA gene confirmed of isolates as an E. coli O157:H7 strain with 99% similarities. Furthermore, the risk factors analysis showed that the slope of the cage floor has a highly significant effect (P<0.05) to the distribution of infection. Consequently, implementing this factor must be concerned in order to decrease of infection. Copyright © 2017 Elsevier B.V. All rights reserved.

Cytotoxic Necrotizing Factor-1 (CNF1) does not promote E. coli infection in a murine model of ascending pyelonephritis.

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Michaud, Jason E; Kim, Kwang Sik; Harty, William; Kasprenski, Matthew; Wang, Ming-Hsien

2017-05-25

Urinary tract infections (UTI) are among the most common and costly infections in both hospitalized and ambulatory patients. Uropathogenic E. coli (UPEC) represent the majority of UTI isolates and are a diverse group of bacteria that utilize a variety of virulence factors to establish infection of the genitourinary tract. The virulence factor cytotoxic necrotizing factor-1 (CNF1) is frequently expressed in clinical UPEC isolates. To date, there have been conflicting reports on the role of CNF1 in the pathogenesis of E. coli urinary tract infections. We examined the importance of CNF1 in a murine ascending kidney infection/ pyelonephritis model by performing comparative studies between a clinical UPEC isolate strain and a CNF1-deletion mutant. We found no alterations in bacterial burden with the loss of CNF1, whereas loss of the virulence factor fimH decreased bacterial burdens. In addition, we found no evidence that CNF1 contributed to the recruitment of inflammatory infiltrates in the kidney or bladder in vivo. While further examination of CNF-1 may reveal a role in UTI pathogenesis, our data casts doubt on the role of CNF-1 in the pathogenesis of UPEC UTI. As with other infections, different models and approaches are needed to elucidate the contribution of CNF1 to E. coli UTI.

Stability of tokamaks with elongated cross section

International Nuclear Information System (INIS)

An, C.H.; Bateman, G.

1978-08-01

Fixed boundary n = 1 MHD instabilities are studied computationally as a function of diamagnetism (β/sub pol/) and current profile in elongated toroidal equilibria (1 2) or a diamagnetic plasma (β/sub pol/ > 1) with only a mildly elongated cross section

Characterization of Elongation Factor Tu of Mycoplasma ovipneumoniae

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Xuan Zhang, Yue-feng Chu, Ping Zhao, Peng-cheng Gao, Ying He, Nu Wang and Zhong-xin Lu*

2013-11-01

Full Text Available Mycoplasma ovipneumoniae is considered as an important pathogen of small ruminants, but its antigenic proteins are not well known so far. In this study, we cloned the EF-Tu gene of M. ovipneumoniae and analyzed the molecular features of the gene and its coding protein for the first time. The gene was then expressed in E.coli and the antigenicity of the coding protein was evaluated as well. The EF-Tu gene of M. ovipneumoniae is 1209 bp in length, encodes 402 amino acids, and shares the highest DNA sequence identity of 87.5% and deduced amino acid sequence identity of 97.8% with those of M. hyopneumoniae, respectively. The recombinant EF-Tu protein can react with the polyclonal antiserum of M. ovipneumoniae and can induce humoral immune responses in mice, which indicated that the EF-Tu may be used as a candidate protein in developing the technologies to control the disease.

High n ballooning modes in highly elongated tokamaks

International Nuclear Information System (INIS)

An, C.H.; Bateman, G.

1980-02-01

An analytic study of stability against high n ballooning modes in highly elongated axisymmetric plasmas is presented and compared with computational results. From the equation for the marginal pressure gradient, it is found that the local shear plays an important role on the stability of elongated and shifted plasma, and that high elongation deteriorates the stability by decreasing the stabilizing effects of field line bending and local shear. The net contribution of the local shear to stability decreases with elongation and shift for strongly ballooning modes (eigenfunctions strongly localized near the outer edge of the toroidal flux surfaces) but increases for interchange modes (eigenfunctions more uniform along the flux surfaces). The computational study of high n ballooning modes in a highly elongated plasma reveals that lowering the aspect ratio and broadening the pressure profile enhance the marginal beta for β/sub p/ less than unity but severely reduce the marginal beta for β/sub p/ larger than unity

Study of the effects of high-energy proton beams on escherichia coli

Science.gov (United States)

Park, Jeong Chan; Jung, Myung-Hwan

2015-10-01

Antibiotic-resistant bacterial infection is one of the most serious risks to public health care today. However, discouragingly, the development of new antibiotics has progressed little over the last decade. There is an urgent need for alternative approaches to treat antibiotic-resistant bacteria. Novel methods, which include photothermal therapy based on gold nano-materials and ionizing radiation such as X-rays and gamma rays, have been reported. Studies of the effects of high-energy proton radiation on bacteria have mainly focused on Bacillus species and its spores. The effect of proton beams on Escherichia coli (E. coli) has been limitedly reported. Escherichia coli is an important biological tool to obtain metabolic and genetic information and is a common model microorganism for studying toxicity and antimicrobial activity. In addition, E. coli is a common bacterium in the intestinal tract of mammals. In this research, the morphological and the physiological changes of E. coli after proton irradiation were investigated. Diluted solutions of cells were used for proton beam radiation. LB agar plates were used to count the number of colonies formed. The growth profile of the cells was monitored by using the optical density at 600 nm. The morphology of the irradiated cells was observed with an optical microscope. A microarray analysis was performed to examine the gene expression changes between irradiated samples and control samples without irradiation. E coli cells have observed to be elongated after proton irradiation with doses ranging from 13 to 93 Gy. Twenty-two were up-regulated more than twofold in proton-irradiated samples (93 Gy) compared with unexposed one.

The effect of environmental factors and migration dynamics on the prevalence of antibiotic-resistant Escherichia coli in estuary environments

OpenAIRE

Na, Guangshui; Lu, Zihao; Gao, Hui; Zhang, Linxiao; Li, Qianwei; Li, Ruijing; Yang, Fan; Huo, Chuanlin; Yao, Ziwei

2018-01-01

Understanding the antibiotic resistance transmission mechanisms and migration dynamics of antibiotic-resistant bacteria (ARB) in the natural environment is critical given the increasing prevalence of antibiotic resistance. The aim of this study was to examine the fate of sulfonamide-resistant fecal bacteria (E. coli) in an estuary ecosystem and to explore the role and contribution of environmental factors in this process. The prevalence of sulfonamide-resistance status of E. coli was analyzed...

Multifactorial effects of ambient temperature, precipitation, farm management, and environmental factors determine the level of generic Escherichia coli contamination on preharvested spinach.

Science.gov (United States)

Park, Sangshin; Navratil, Sarah; Gregory, Ashley; Bauer, Arin; Srinath, Indumathi; Szonyi, Barbara; Nightingale, Kendra; Anciso, Juan; Jun, Mikyoung; Han, Daikwon; Lawhon, Sara; Ivanek, Renata

2015-04-01

A repeated cross-sectional study was conducted to identify farm management, environment, weather, and landscape factors that predict the count of generic Escherichia coli on spinach at the preharvest level. E. coli was enumerated for 955 spinach samples collected on 12 farms in Texas and Colorado between 2010 and 2012. Farm management and environmental characteristics were surveyed using a questionnaire. Weather and landscape data were obtained from National Resources Information databases. A two-part mixed-effect negative binomial hurdle model, consisting of a logistic and zero-truncated negative binomial part with farm and date as random effects, was used to identify factors affecting E. coli counts on spinach. Results indicated that the odds of a contamination event (non-zero versus zero counts) vary by state (odds ratio [OR] = 108.1). Odds of contamination decreased with implementation of hygiene practices (OR = 0.06) and increased with an increasing average precipitation amount (mm) in the past 29 days (OR = 3.5) and the application of manure (OR = 52.2). On contaminated spinach, E. coli counts increased with the average precipitation amount over the past 29 days. The relationship between E. coli count and the average maximum daily temperature over the 9 days prior to sampling followed a quadratic function with the highest bacterial count at around 24°C. These findings indicate that the odds of a contamination event in spinach are determined by farm management, environment, and weather factors. However, once the contamination event has occurred, the count of E. coli on spinach is determined by weather only. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

pix-1 controls early elongation in parallel with mel-11 and let-502 in Caenorhabditis elegans.

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Martin, Emmanuel; Harel, Sharon; Nkengfac, Bernard; Hamiche, Karim; Neault, Mathieu; Jenna, Sarah

2014-01-01

Cell shape changes are crucial for metazoan development. During Caenorhabditis elegans embryogenesis, epidermal cell shape changes transform ovoid embryos into vermiform larvae. This process is divided into two phases: early and late elongation. Early elongation involves the contraction of filamentous actin bundles by phosphorylated non-muscle myosin in a subset of epidermal (hypodermal) cells. The genes controlling early elongation are associated with two parallel pathways. The first one involves the rho-1/RHOA-specific effector let-502/Rho-kinase and mel-11/myosin phosphatase regulatory subunit. The second pathway involves the CDC42/RAC-specific effector pak-1. Late elongation is driven by mechanotransduction in ventral and dorsal hypodermal cells in response to body-wall muscle contractions, and involves the CDC42/RAC-specific Guanine-nucleotide Exchange Factor (GEF) pix-1, the GTPase ced-10/RAC and pak-1. In this study, pix-1 is shown to control early elongation in parallel with let-502/mel-11, as previously shown for pak-1. We show that pix-1, pak-1 and let-502 control the rate of elongation, and the antero-posterior morphology of the embryos. In particular, pix-1 and pak-1 are shown to control head, but not tail width, while let-502 controls both head and tail width. This suggests that let-502 function is required throughout the antero-posterior axis of the embryo during early elongation, while pix-1/pak-1 function may be mostly required in the anterior part of the embryo. Supporting this hypothesis we show that low pix-1 expression level in the dorsal-posterior hypodermal cells is required to ensure high elongation rate during early elongation.

Shiga toxin-producing Escherichia coli isolated from chicken meat in Iran: serogroups, virulence factors, and antimicrobial resistance properties.

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Momtaz, Hassan; Jamshidi, Alireza

2013-05-01

The aim of the current study was to determine the virulence factors, serogroups, and antibiotic resistance properties of Shiga toxin-producing Escherichia coli isolated from chicken meat samples. A total of 422 chicken meat samples were collected from 5 townships of Iran. Specimens were immediately transferred to the laboratory in a cooler with an ice pack. Samples were cultured, and the positive culture samples were analyzed by PCR assays. Finally, the antimicrobial susceptibility test was performed using the disk diffusion method in Mueller-Hinton agar. According to the results, out of 422 samples, 146 (34.59%) were confirmed to be E. coli positive and among E. coli-positive samples, 51 (34.93%) and 31 (21.23%) were from attaching and effacing E. coli (AEEC) and enterohemorrhagic E. coli (EHEC) subgroups, respectively. All of the EHEC-positive samples had all stx1, eaeA, and ehly virulence genes, whereas only 5 (9.80%) of AEEC subgroup had all stx1, stx2, and eaeA genes. As the data revealed, O157 was the most prevalent and O111 was the least prevalent strains in the Shiga toxin-producing E. coli (STEC) population. Among STEC strains, sulI and blaSHV had the highest and lowest incidence rate, respectively. There was a high resistance to tetracycline (76.82%), followed by chloramphenicol (73.17%) and nitrofurantoin (63.41%), but there was low resistance to cephalotine (7.31%) antibiotics in isolated strains. Results shows that the PCR technique has a high performance for detection of serogroups, virulence genes, and antibiotic resistance genes in STEC strains. This study is the first prevalence report of detection of virulence genes, serogroups, and antibiotic resistance properties of STEC strains isolated from chicken meat samples in Iran. Based on the results, chicken meat is one of the main sources of STEC strains and its virulence factors in Iran, so an accurate meat inspection would reduce disease outbreaks.

Abscisic Acid Stimulates Elongation of Excised Pea Root Tips

Science.gov (United States)

Gaither, Douglas H.; Lutz, Donald H.; Forrence, Leonard E.

1975-01-01

Excised Pisum sativum L. root tips were incubated in a pH 5.2 sucrose medium containing abscisic acid. Elongation growth was inhibited by 100 μm abscisic acid. However, decreasing the abscisic acid concentration caused stimulation of elongation, the maximum response (25% to 30%) occurring at 1 μm abscisic acid. Prior to two hours, stimulation of elongation by 1 μm abscisic acid was not detectable. Increased elongation did not occur in abscisic acid-treated root tips of Lens culinaris L., Phaseolus vulgaris L., or Zea mays L. PMID:16659198

A transcription elongation factor that links signals from the reproductive system to lifespan extension in Caenorhabditis elegans.

Directory of Open Access Journals (Sweden)

Arjumand Ghazi

2009-09-01

Full Text Available In Caenorhabditis elegans and Drosophila melanogaster, the aging of the soma is influenced by the germline. When germline-stem cells are removed, aging slows and lifespan is increased. The mechanism by which somatic tissues respond to loss of the germline is not well-understood. Surprisingly, we have found that a predicted transcription elongation factor, TCER-1, plays a key role in this process. TCER-1 is required for loss of the germ cells to increase C. elegans' lifespan, and it acts as a regulatory switch in the pathway. When the germ cells are removed, the levels of TCER-1 rise in somatic tissues. This increase is sufficient to trigger key downstream events, as overexpression of tcer-1 extends the lifespan of normal animals that have an intact reproductive system. Our findings suggest that TCER-1 extends lifespan by promoting the expression of a set of genes regulated by the conserved, life-extending transcription factor DAF-16/FOXO. Interestingly, TCER-1 is not required for DAF-16/FOXO to extend lifespan in animals with reduced insulin/IGF-1 signaling. Thus, TCER-1 specifically links the activity of a broadly deployed transcription factor, DAF-16/FOXO, to longevity signals from reproductive tissues.

A pollen-specific RALF from tomato that regulates pollen tube elongation.

Science.gov (United States)

Covey, Paul A; Subbaiah, Chalivendra C; Parsons, Ronald L; Pearce, Gregory; Lay, Fung T; Anderson, Marilyn A; Ryan, Clarence A; Bedinger, Patricia A

2010-06-01

Rapid Alkalinization Factors (RALFs) are plant peptides that rapidly increase the pH of plant suspension cell culture medium and inhibit root growth. A pollen-specific tomato (Solanum lycopersicum) RALF (SlPRALF) has been identified. The SlPRALF gene encodes a preproprotein that appears to be processed and released from the pollen tube as an active peptide. A synthetic SlPRALF peptide based on the putative active peptide did not affect pollen hydration or viability but inhibited the elongation of normal pollen tubes in an in vitro growth system. Inhibitory effects of SlPRALF were detectable at concentrations as low as 10 nm, and complete inhibition was observed at 1 mum peptide. At least 10-fold higher levels of alkSlPRALF, which lacks disulfide bonds, were required to see similar effects. A greater effect of peptide was observed in low-pH-buffered medium. Inhibition of pollen tube elongation was reversible if peptide was removed within 15 min of exposure. Addition of 100 nm SlPRALF to actively growing pollen tubes inhibited further elongation until tubes were 40 to 60 mum in length, after which pollen tubes became resistant to the peptide. The onset of resistance correlated with the timing of the exit of the male germ unit from the pollen grain into the tube. Thus, exogenous SlPRALF acts as a negative regulator of pollen tube elongation within a specific developmental window.

Planar Elongation Measurements on Soft Elastomers

DEFF Research Database (Denmark)

Jensen, Mette Krog; Skov, Anne Ladegaard; Rasmussen, Henrik K.

2009-01-01

A new fixture to the filament stretch rheometer (FSR) has been developed to measure planar elongation of soft polymeric networks. To validate this new technique, soft polymeric networks of poly(propyleneoxide) (PPO) were investigated during deformation.......A new fixture to the filament stretch rheometer (FSR) has been developed to measure planar elongation of soft polymeric networks. To validate this new technique, soft polymeric networks of poly(propyleneoxide) (PPO) were investigated during deformation....

Positive grid corrosion elongation analysis using CAE with corrosion deformation transformed into thermal phenomenon

Science.gov (United States)

Mukaitani, Ichiroh; Hayashi, Koji; Shimoura, Ichiro; Takemasa, Arihiko; Takahashi, Isamu; Tsubakino, Harushige

Valve-regulated lead-acid (VRLA) batteries have been commercially available for more than 20 years and have been enthusiastically embraced by users of uninterruptible power supplies (UPS) because of the anticipated reduction in installation and operating costs, smaller footprint and fewer environmental concerns. In Japan, communication networks are demanding reduced costs and longer life from their batteries. Among the factors limiting the life of VRLA batteries, the corrosion of positive grid material has been proven to cause elongation of the plates, loss of electrical contact and shorter lifetime. The content of Sn is also a key factor and addition of Sn in the grid alloy results in better performance in creep resistance, tensile strength and corrosion resistance [R. David Prenagaman, The Battery Man, vol. 39, September 1997, p. 16. I. Mukaitani, T. Sakamoto, T. Kikuoka, Y. Yamaguchi, H. Tsubakino, Proceedings of the 40th Battery Symposium in Japan, 1999, p. 99]. A key point is what the ratio of Sn to Ca should be, since too much Sn may lead to even worse elongation of the plates [I. Mukaitani, T. Sakamoto, T. Kikuoka, Y. Yamaguchi, H. Tsubakino, Proceedings of the 40th Battery Symposium in Japan, 1999, p. 99]. We have determined that microstructure control with a composition of lead-calcium-tin (Pb-Ca-Sn) alloy is optimal for better performance of the plates [I. Mukaitani, T. Sakamoto, T. Kikuoka, Y. Yamaguchi, H. Tsubakino, Proceedings of the 40th Battery Symposium in Japan, 1999, p. 99]. We developed a "simulation of current collector corrosion elongation" which is a technique of estimating corrosion elongation from the current collector design [I. Mukaitani, K. Hayashi, I. Shimoura, H. Takabayashi, M. Terada, A. Takemasa, I. Takahashi, K. Okamoto, Proceedings of the 44th Battery Symposium in Japan, 2003, p. 652]. Corrosion elongation occurs as the corrosion material layer grows out of the current collector metal. We resolved this problem using generally CAD

Putative new heat-stable cytotoxic and enterotoxic factors in culture supernatant of Escherichia coli isolated from drinking water

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DA Ribeiro

2011-01-01

Full Text Available Enteric infections caused by the ingestion of contaminated water, especially by Escherichia coli, are important to define the virulence properties of these bacteria. Due to frequent infantile diarrhea in the city of Ouro Preto, Minas Gerais state, Brazil, the phenotypic and genotypic diarrheagenic properties of E. coli isolated from drinking water were studied. The culture supernatants of 39 (40% among a total of 97 E. coli isolates from drinking water were positive by suckling mouse assay and induced cytotoxic effects on Vero cells. The enterotoxic and cytotoxic activities were present in the fraction with less than 10 kDa and were not lost when heated up to 60°C and 100°C for 30 minutes. PCR assays showed that among these 39 Vero cytotoxigenic E. coli, four (10.2% were positive for ST II (estB and two (5% positive for αHly (hlyA. Gene amplification of SLT (stx 1, stx 2, ST I (estA, LT (eltI, eltII, EAST1 (astA, EHly (enhly and plasmid-encoded enterotoxin (pet were not observed. This heat-stable cytotoxic enterotoxin of E. coli is probably a new putative diarrheagenic virulence factor, as a toxin presenting these characteristics has not yet been described.

New discoveries linking transcription to DNA repair and damage tolerance pathways.

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Cohen, Susan E; Walker, Graham C

2011-01-01

In Escherichia coli, the transcription elongation factor NusA is associated with all elongating RNA polymerases where it functions in transcription termination and antitermination. Here, we review our recent results implicating NusA in the recruitment of DNA repair and damage tolerance mechanisms to sites of stalled transcription complexes.

Halogenated auxins affect microtubules and root elongation in Lactuca sativa

Science.gov (United States)

Zhang, N.; Hasenstein, K. H.

2000-01-01

We studied the effect of 4,4,4-trifluoro-3-(indole-3-)butyric acid (TFIBA), a recently described root growth stimulator, and 5,6-dichloro-indole-3-acetic acid (DCIAA) on growth and microtubule (MT) organization in roots of Lactuca sativa L. DCIAA and indole-3-butyric acid (IBA) inhibited root elongation and depolymerized MTs in the cortex of the elongation zone, inhibited the elongation of stele cells, and promoted xylem maturation. Both auxins caused the plane of cell division to shift from anticlinal to periclinal. In contrast, TFIBA (100 micromolar) promoted elongation of primary roots by 40% and stimulated the elongation of lateral roots, even in the presence of IBA, the microtubular inhibitors oryzalin and taxol, or the auxin transport inhibitor naphthylphthalamic acid. However, TFIBA inhibited the formation of lateral root primordia. Immunostaining showed that TFIBA stabilized MTs orientation perpendicular to the root axis, doubled the cortical cell length, but delayed xylem maturation. The data indicate that the auxin-induced inhibition of elongation and swelling of roots results from reoriented phragmoplasts, the destabilization of MTs in elongating cells, and promotion of vessel formation. In contrast, TFIBA induced promotion of root elongation by enhancing cell length, prolonging transverse MT orientation, delaying cell and xylem maturation.

Fimbrial adhesins from extraintestinal Escherichia coli

DEFF Research Database (Denmark)

Klemm, Per; Hancock, Viktoria; Schembri, Mark A.

2010-01-01

Extraintestinal pathogenic Escherichia coli (ExPEC) represent an important subclass of E. coli that cause a wide spectrum of diseases in human and animal hosts. Fimbriae are key virulence factors of ExPEC strains. These long surface located rod-shaped organelles mediate receptor-specific attachment...

Virulence factors, serogroups and antimicrobial resistance properties of Escherichia coli strains in fermented dairy products.

Science.gov (United States)

Dehkordi, Farhad Safarpoor; Yazdani, Farshad; Mozafari, Jalal; Valizadeh, Yousef

2014-04-07

From a clinical perspective, it is essential to know the microbial safety of fermented dairy products. Doogh and kashk are fermented dairies. These products are used by millions of people but their microbial qualities are unknown. Shiga toxin producing Escherichia coli (STEC) is one of the most commonly detected pathogens in the cases of food poisoning and food-borne illnesses. The present investigation was carried out in order to study the molecular characterization and antimicrobial resistance properties of STEC strains isolated from fermented dairy products. Six hundred fermented dairy samples were collected and immediately transferred to the laboratory. All samples were cultured immediately and those that were E. coli-positive were analyzed for the presence of O157 , O26, O103, O111, O145, O45, O91, O113, O121 and O128 STEC serogroups, tetA, tetB, blaSHV, CITM, cmlA, cat1, aadA1, dfrA1, qnr, aac (3)-IV, sul1 and ereA antibiotic resistance genes and stx1, stx2, eaeA, ehly, cnf1, cnf2, iutA, cdtB, papA, traT, sfaS and fyuA virulence factors using PCR. Antimicrobial susceptibility testing was performed also using disk diffusion methodology with Mueller-Hinton agar. Fifty out of 600 (8.33%) dairy samples harbored E. coli. In addition, yoghurt was the most commonly contaminated dairy. O157 (26%) and O26 (12%) were the most commonly detected serogroups. A significant difference was found between the frequency of Attaching and Effacing E. coli and Enterohaemorrhagic E. coli (P Fermented dairy products can easily become contaminated by antibiotic resistant STEC strains. Our findings should raise awareness about antibiotic resistance in Iran. Clinicians should exercise caution when prescribing antibiotics, especially in veterinary treatments.

The transcription elongation factor ELL2 is specifically upregulated in HTLV-1-infected T-cells and is dependent on the viral oncoprotein Tax

Energy Technology Data Exchange (ETDEWEB)

Mann, Melanie C., E-mail: melanie.mann@viro.med.uni-erlangen.de; Strobel, Sarah, E-mail: sarah.strobel@viro.med.uni-erlangen.de; Fleckenstein, Bernhard, E-mail: bernhard.fleckenstein@viro.med.uni-erlangen.de; Kress, Andrea K., E-mail: andrea.kress@viro.med.uni-erlangen.de

2014-09-15

The oncoprotein Tax of human T-cell leukemia virus type 1 (HTLV-1) is a potent transactivator of viral and cellular transcription. Here, we identified ELL2 as the sole transcription elongation factor to be specifically upregulated in HTLV-1-/Tax-transformed T-cells. Tax contributes to regulation of ELL2, since transient transfection of Tax increases ELL2 mRNA, Tax transactivates the ELL2 promoter, and repression of Tax results in decrease of ELL2 in transformed T-lymphocytes. However, we also measured upregulation of ELL2 in HTLV-1-transformed cells exhibiting undetectable amounts of Tax, suggesting that ELL2 can still be maintained independent of continuous Tax expression. We further show that Tax and ELL2 synergistically activate the HTLV-1 promoter, indicating that ELL2 cooperates with Tax in viral transactivation. This is supported by our findings that Tax and ELL2 accumulate in nuclear fractions and that they co-precipitate upon co-expression in transiently-transfected cells. Thus, upregulation of ELL2 could contribute to HTLV-1 gene regulation. - Highlights: • ELL2, a transcription elongation factor, is upregulated in HTLV-1-positive T-cells. • Tax transactivates the ELL2 promoter. • Tax and ELL2 synergistically activate the HTLV-1 promoter. • Tax and ELL2 interact in vivo.

The transcription elongation factor ELL2 is specifically upregulated in HTLV-1-infected T-cells and is dependent on the viral oncoprotein Tax

International Nuclear Information System (INIS)

Mann, Melanie C.; Strobel, Sarah; Fleckenstein, Bernhard; Kress, Andrea K.

2014-01-01

The oncoprotein Tax of human T-cell leukemia virus type 1 (HTLV-1) is a potent transactivator of viral and cellular transcription. Here, we identified ELL2 as the sole transcription elongation factor to be specifically upregulated in HTLV-1-/Tax-transformed T-cells. Tax contributes to regulation of ELL2, since transient transfection of Tax increases ELL2 mRNA, Tax transactivates the ELL2 promoter, and repression of Tax results in decrease of ELL2 in transformed T-lymphocytes. However, we also measured upregulation of ELL2 in HTLV-1-transformed cells exhibiting undetectable amounts of Tax, suggesting that ELL2 can still be maintained independent of continuous Tax expression. We further show that Tax and ELL2 synergistically activate the HTLV-1 promoter, indicating that ELL2 cooperates with Tax in viral transactivation. This is supported by our findings that Tax and ELL2 accumulate in nuclear fractions and that they co-precipitate upon co-expression in transiently-transfected cells. Thus, upregulation of ELL2 could contribute to HTLV-1 gene regulation. - Highlights: • ELL2, a transcription elongation factor, is upregulated in HTLV-1-positive T-cells. • Tax transactivates the ELL2 promoter. • Tax and ELL2 synergistically activate the HTLV-1 promoter. • Tax and ELL2 interact in vivo

Stress relaxation of entangled polystyrene solution after constant-rate, uniaxial elongation

DEFF Research Database (Denmark)

Matsumiya, Yumi; Masubuchi, Yuichi; Watanabe, Hiroshi

For an entangled solution of linear polystyrene (PS 545k; M = 545k) in dibutyl phthalate (DBP), the stress relaxation after constant-rate uniaxial elongation was examined with an extensional viscosity fixture mounted on ARES (TA Instruments). The PS concentration, c = 52 wt%, was chosen in a way...... that the entanglement density M/Me of the solution coincided with that of PS 290k melt (M = 290k). After the elongation at the Rouse-based Weissenberg number Wi(R) ~ 3 up to the Hencky strain of 3, the short time stress relaxation of the solution was accelerated by a factor of ~4, which was less significant compared...... and the lack of monotonic thinning observed for the semidilute solutions. Results for less concentrated solutions will be also presented on site....

Elongation of Flare Ribbons

Energy Technology Data Exchange (ETDEWEB)

Qiu, Jiong; Longcope, Dana W. [Department of Physics, Montana State University, Bozeman MT (United States); Cassak, Paul A. [Department of Physics and Astronomy, West Virginia University, Morgantown WV (United States); Priest, Eric R. [School of Mathematics and Statistics, University of St. Andrews, Fife KY16 9SS, Scotland (United Kingdom)

2017-03-20

We present an analysis of the apparent elongation motion of flare ribbons along the polarity inversion line (PIL), as well as the shear of flare loops in several two-ribbon flares. Flare ribbons and loops spread along the PIL at a speed ranging from a few to a hundred km s{sup −1}. The shear measured from conjugate footpoints is consistent with the measurement from flare loops, and both show the decrease of shear toward a potential field as a flare evolves and ribbons and loops spread along the PIL. Flares exhibiting fast bidirectional elongation appear to have a strong shear, which may indicate a large magnetic guide field relative to the reconnection field in the coronal current sheet. We discuss how the analysis of ribbon motion could help infer properties in the corona where reconnection takes place.

A Multi-Country Cross-Sectional Study of Vaginal Carriage of Group B Streptococci (GBS and Escherichia coli in Resource-Poor Settings: Prevalences and Risk Factors.

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Piet Cools

Full Text Available One million neonates die each year in low- and middle-income countries because of neonatal sepsis; group B Streptococcus (GBS and Escherichia coli are the leading causes. In sub-Saharan Africa, epidemiological data on vaginal GBS and E. coli carriage, a prerequisite for GBS and E. coli neonatal sepsis, respectively, are scarce but necessary to design and implement prevention strategies. Therefore, we assessed vaginal GBS and E. coli carriage rates and risk factors and the GBS serotype distribution in three sub-Saharan countries.A total of 430 women from Kenya, Rwanda and South Africa were studied cross-sectionally. Vaginal carriage of GBS and E. coli, and GBS serotype were assessed using molecular techniques. Risk factors for carriage were identified using multivariable logistic regression analysis.Vaginal carriage rates in reference groups from Kenya and South Africa were 20.2% (95% CI, 13.7-28.7% and 23.1% (95% CI, 16.2-31.9%, respectively for GBS; and 25.0% (95% CI, 17.8-33.9% and 27.1% (95% CI, 19.6-36.2%, respectively for E. coli. GBS serotypes Ia (36.8%, V (26.3% and III (14.0% were most prevalent. Factors independently associated with GBS and E. coli carriage were Candida albicans, an intermediate vaginal microbiome, bacterial vaginosis, recent vaginal intercourse, vaginal washing, cervical ectopy and working as a sex worker. GBS and E. coli carriage were positively associated.Reduced vaginal GBS carriage rates might be accomplished by advocating behavioral changes such as abstinence from sexual intercourse and by avoidance of vaginal washing during late pregnancy. It might be advisable to explore the inclusion of vaginal carriage of C. albicans, GBS, E. coli and of the presence of cervical ectopy in a risk- and/or screening-based administration of antibiotic prophylaxis. Current phase II GBS vaccines (a trivalent vaccine targeting serotypes Ia, Ib, and III, and a conjugate vaccine targeting serotype III would not protect the majority of

Elongational viscosity of photo-oxidated LDPE

Science.gov (United States)

Rolón-Garrido, Víctor H.; Wagner, Manfred H.

2014-05-01

Sheets of low-density polyethylene (LDPE) were photo-oxidatively treated at room temperature, and subsequently characterized rheologically in the melt state by shear and uniaxial extensional experiments. For photo-oxidation, a xenon lamp was used to irradiate the samples for times between 1 day and 6 weeks. Linear-viscoelastic characterization was performed in a temperature range of 130 to 220°C to obtain the master curve at 170°C, the reference temperature at which the elongational viscosities were measured. Linear viscoelasticity is increasingly affected by increasing photo-oxidation due to crosslinking of LDPE, as corroborated by an increasing gel fraction as determined by a solvent extraction method. The elongational measurements reveal a strong enhancement of strain hardening until a saturation level is achieved. The elongational data are analyzed in the frame work of two constitutive equations, the rubber-like liquid and the molecular stress function models. Within the experimental window, timedeformation separability is confirmed for all samples, independent of the degree of photo-oxidation.

Chromosomal features of Escherichia coli serotype O2:K2, an avian pathogenic E. coli.

Science.gov (United States)

Jørgensen, Steffen L; Kudirkiene, Egle; Li, Lili; Christensen, Jens P; Olsen, John E; Nolan, Lisa; Olsen, Rikke H

2017-01-01

Escherichia coli causing infection outside the gastrointestinal system are referred to as extra-intestinal pathogenic E. coli. Avian pathogenic E. coli is a subgroup of extra-intestinal pathogenic E. coli and infections due to avian pathogenic E. coli have major impact on poultry production economy and welfare worldwide. An almost defining characteristic of avian pathogenic E. coli is the carriage of plasmids, which may encode virulence factors and antibiotic resistance determinates. For the same reason, plasmids of avian pathogenic E. coli have been intensively studied. However, genes encoded by the chromosome may also be important for disease manifestation and antimicrobial resistance. For the E. coli strain APEC_O2 the plasmids have been sequenced and analyzed in several studies, and E. coli APEC_O2 may therefore serve as a reference strain in future studies. Here we describe the chromosomal features of E. coli APEC_O2. E. coli APEC_O2 is a sequence type ST135, has a chromosome of 4,908,820 bp (plasmid removed), comprising 4672 protein-coding genes, 110 RNA genes, and 156 pseudogenes, with an average G + C content of 50.69%. We identified 82 insertion sequences as well as 4672 protein coding sequences, 12 predicated genomic islands, three prophage-related sequences, and two clustered regularly interspaced short palindromic repeats regions on the chromosome, suggesting the possible occurrence of horizontal gene transfer in this strain. The wildtype strain of E. coli APEC_O2 is resistant towards multiple antimicrobials, however, no (complete) antibiotic resistance genes were present on the chromosome, but a number of genes associated with extra-intestinal disease were identified. Together, the information provided here on E. coli APEC_O2 will assist in future studies of avian pathogenic E. coli strains, in particular regarding strain of E. coli APEC_O2, and aid in the general understanding of the pathogenesis of avian pathogenic E. coli .

Colonization of Enteroaggregative Escherichia coli and Shiga toxin-producing Escherichia coli in chickens and humans in southern Vietnam

NARCIS (Netherlands)

Trung, Nguyen Vinh; Nhung, Hoang Ngoc; Carrique-Mas, Juan J.; Mai, Ho Huynh; Tuyen, Ha Thanh; Campbell, James; Nhung, Nguyen Thi; van Minh, Pham; Wagenaar, Jaap A.; Mai, Nguyen Thi Nhu; Hieu, Thai Quoc; Schultsz, Constance; Hoa, Ngo Thi

2016-01-01

Enteroaggregative (EAEC) and Shiga-toxin producing Escherichia coli (STEC) are a major cause of diarrhea worldwide. E. coli carrying both virulence factors characteristic for EAEC and STEC and producing extended-spectrum beta-lactamase caused severe and protracted disease during an outbreak of E.

Transcription factor DecR (YbaO) controls detoxification of L-cysteine in Escherichia coli.

Science.gov (United States)

Shimada, Tomohiro; Tanaka, Kan; Ishihama, Akira

2016-09-01

YbaO is an uncharacterized AsnC-family transcription factor of Escherichia coli. In both Salmonella enterica and Pantoea ananatis, YbaO homologues were identified to regulate the adjacent gene encoding cysteine desulfhydrase for detoxification of cysteine. Using the genomic SELEX (systematic evolution of ligands by exponential enrichment) screening system, we identified the yhaOM operon, located far from the ybaO gene on the E. coli genome, as a single regulatory target of YbaO. In both gel shift assay in vitro and reporter and Northern blot assays in vivo, YbaO was found to regulate the yhaOM promoter. The growth of mutants lacking either ybaO or its targets yhaOM was delayed in the presence of cysteine, indicating involvement of these genes in cysteine detoxification. In the major pathway of cysteine degradation, hydrogen sulfide is produced in wild-type E. coli, but its production was not observed in each of the ybaO, yhaO and yhaM mutants. The yhaOM promoter was activated in the presence of cysteine, implying the role of cysteine in activation of YbaO. Taken together, we propose that YbaO is the cysteine-sensing transcriptional activator of the yhaOM operon, which is involved in the detoxification of cysteine. We then propose the naming of ybaO as decR (regulator of detoxification of cysteine).

Bilateral elongated styloid process: Its anatomical, embryological and clinical implications

OpenAIRE

Bagoji Ishwar B, Hadimani Gavishiddappa A, Patil Balasaheb G, Bannur Balappa M,Ambadasu B

2013-01-01

The styloid process is a slender, elongated, cylindrical bony projection from temporal bone. It normally varies in length from 2 cm to 3 cm. During a routine demonstration of skull for MBBS students we found the bilateral elongated styloid process in dry human skull. The length of elongation measured on the right and left side was 6.0 & 5.9 cms respectively. Such abnormal elongation of the styloid process may cause compression on a number of vital vessels and nerves related to it, producing i...

Regulation of oxidative enzyme activity and eukaryotic elongation factor 2 in human skeletal muscle: influence of gender and exercise

DEFF Research Database (Denmark)

Roepstorff, Carsten; Schjerling, P.; Vistisen, Bodil

2005-01-01

AIM: To investigate gender-related differences in the responses of oxidative enzymes and eukaryotic elongation factor-2 (eEF2) to exercise. METHODS: The influence of exercise (90 min, 60%VO(2peak)) on citrate synthase (CS) and beta-hydroxyacyl-CoA dehydrogenase (HAD) activity and mRNA content...... expression and phosphorylation were unaffected by training status (NS). CONCLUSION: Basal transcriptional, translational, and/or post-translational control of CS and HAD seems to be gender-dependent. Also, gender differences in translation and/or post-translational protein modification of CS occur during...... not differ between females and males (NS). In females only, CS activity was enhanced (P differ between UT and ET but, nevertheless, CS activity was 56% higher in ET than in UT volunteers (P

Fatty Acid Elongation in Non-Alcoholic Steatohepatitis and Hepatocellular Carcinoma

Directory of Open Access Journals (Sweden)

Sonja M. Kessler

2014-04-01

Full Text Available Non-alcoholic steatohepatitis (NASH represents a risk factor for the development of hepatocellular carcinoma (HCC and is characterized by quantitative and qualitative changes in hepatic lipids. Since elongation of fatty acids from C16 to C18 has recently been reported to promote both hepatic lipid accumulation and inflammation we aimed to investigate whether a frequently used mouse NASH model reflects this clinically relevant feature and whether C16 to C18 elongation can be observed in HCC development. Feeding mice a methionine and choline deficient diet to model NASH not only increased total hepatic fatty acids and cholesterol, but also distinctly elevated the C18/C16 ratio, which was not changed in a model of simple steatosis (ob/ob mice. Depletion of Kupffer cells abrogated both quantitative and qualitative methionine-and-choline deficient (MCD-induced alterations in hepatic lipids. Interestingly, mimicking inflammatory events in early hepatocarcinogenesis by diethylnitrosamine-induced carcinogenesis (48 h increased hepatic lipids and the C18/C16 ratio. Analyses of human liver samples from patients with NASH or NASH-related HCC showed an elevated expression of the elongase ELOVL6, which is responsible for the elongation of C16 fatty acids. Taken together, our findings suggest a detrimental role of an altered fatty acid pattern in the progression of NASH-related liver disease.

Predictors and risk factors for the intestinal shedding of Escherichia coli O157 among working donkeys (Equus asinus) in Nigeria

Science.gov (United States)

Jedial, Jesse T.; Shittu, Aminu; Tambuwal, Faruk M.; Abubakar, Mikail B.; Garba, Muhammed K.; Kwaga, Jacob P.; Fasina, Folorunso O.

2015-01-01

Objectives Escherichia coli are an important group of bacteria in the normal gastrointestinal system but can sometimes cause infections in domestic animals and man. Donkeys are routinely used as multipurpose animal but details of burdens of potentially infectious bacteria associated with it are limited. The prevalence and associations between intestinal shedding of E. coli O157 and animal characteristics and management factors were studied among 240 randomly selected working donkeys in north-western Nigeria. Design Four local government areas, of Sokoto State in north-western Nigeria were recruited in this study. A multistage randomised cluster design was used to select subjects and donkey owners within selected zones. Confirmation of infection was based on bacterial culture, isolation and biochemical test for E. coli O157 from faecal samples. Results Of the total bacteria isolated, 203 of the 329 (61.70 per cent) were E. coli, 76 of which was E. coli serotype O157. A multivariable logistic regression model was used to examine the relation between intestinal shedding of E. coli O157 and selected variables. The analysis yielded five potential predictors of shedding: soft faeces in donkeys, Akaza and Fari ecotypes of donkey were positive predictors while maize straw as feed and sampling during the cold dry period were negative predictors. Conclusions This study concludes that controlling intestinal shedding of E. coli O157 among working donkeys in Nigeria is possible using the identified predictors in planning appropriate interventions to reduced human risk of infection. PMID:26392892

Assessment of relationship between rainfall and Escherichia coli in clams (Chamelea gallina using the Bayes Factor

Directory of Open Access Journals (Sweden)

Cesare Ciccarelli

2017-08-01

Full Text Available Consumption of bivalve shellfish harvested from water contaminated with sewage pollution presents a risk of human infections and targeting control measures require a good understanding of environmental factors influencing the transport and the fate of faecal contaminants within the hydrological catchments. Although there has been extensive development of regression models, the point of this paper, focused on the relationship between rainfall events and concentrations of Escherichia coli monitored in clams, was the use of a Bayesian approach, by the Bayes Factor. The study was conducted on clams harvested from the south coast of Marche Region (Italy, a coastal area impacted by continuous treated effluents, intermittent rainfalldependent untreated sewage spillage - as a consequence of stormwater overflowing - and rivers with an ephemeral flow regime. The work compared the different interpretation criteria of Bayes Factor, confirmed that E. coli concentrations in clams from the studied area varied in correlation with rainfall events, and demonstrated the effectiveness of Bayes Factor in the assessment of shellfish quality in coastal marine waters. However, it suggested that further investigations would be warranted to determine which environmental factors provide the better basis for accurate and timely predictions. Furthermore the gathered data could be useful, to the local authorities of Marche Region, in the definition of flexible monitoring programmes, taking into account the atmospheric events that could affect the correct functioning of sewage managing systems and the flow of tributary rivers.

Using dynamic input allocation for elongation control at FTU

International Nuclear Information System (INIS)

Boncagni, L.; Galeani, S.; Granucci, G.; Varano, G.; Vitale, V.; Zaccarian, L.

2010-01-01

In this paper we exploit the dynamic allocation scheme for input redundant control systems proposed in to achieve elongation control on FTU (Frascati Tokamak Upgrade). The scheme first serves as a means for regulating the current in the F coils. Then, due to the quasi-static relationship between the plasma elongation and the F coils current, elongation control is achieved by suitably generalizing the allocation scheme. Both simulation and experimental results are reported.

Elongation Factor Tu Prevents Misediting of Gly-tRNA(Gly Caused by the Design Behind the Chiral Proofreading Site of D-Aminoacyl-tRNA Deacylase.

Directory of Open Access Journals (Sweden)

Satya Brata Routh

2016-05-01

Full Text Available D-aminoacyl-tRNA deacylase (DTD removes D-amino acids mischarged on tRNAs and is thus implicated in enforcing homochirality in proteins. Previously, we proposed that selective capture of D-aminoacyl-tRNA by DTD's invariant, cross-subunit Gly-cisPro motif forms the mechanistic basis for its enantioselectivity. We now show, using nuclear magnetic resonance (NMR spectroscopy-based binding studies followed by biochemical assays with both bacterial and eukaryotic systems, that DTD effectively misedits Gly-tRNAGly. High-resolution crystal structure reveals that the architecture of DTD's chiral proofreading site is completely porous to achiral glycine. Hence, L-chiral rejection is the only design principle on which DTD functions, unlike other chiral-specific enzymes such as D-amino acid oxidases, which are specific for D-enantiomers. Competition assays with elongation factor thermo unstable (EF-Tu and DTD demonstrate that EF-Tu precludes Gly-tRNAGly misediting at normal cellular concentrations. However, even slightly higher DTD levels overcome this protection conferred by EF-Tu, thus resulting in significant depletion of Gly-tRNAGly. Our in vitro observations are substantiated by cell-based studies in Escherichia coli that show that overexpression of DTD causes cellular toxicity, which is largely rescued upon glycine supplementation. Furthermore, we provide direct evidence that DTD is an RNA-based catalyst, since it uses only the terminal 2'-OH of tRNA for catalysis without the involvement of protein side chains. The study therefore provides a unique paradigm of enzyme action for substrate selection/specificity by DTD, and thus explains the underlying cause of DTD's activity on Gly-tRNAGly. It also gives a molecular and functional basis for the necessity and the observed tight regulation of DTD levels, thereby preventing cellular toxicity due to misediting.

Measurement and analysis of pressure tube elongation in the Douglas Point reactor

International Nuclear Information System (INIS)

Causey, A.R.; MacEwan, S.R.; Jamieson, H.C.; Mitchell, A.B.

1980-02-01

Elongations of zirconium alloy pressure tubes in CANDU reactors, which occur as a result of neutron-irradiation-induced creep and growth, have been measured over the past 6 years, and the consequences of thses elongations have recently been analysed. Elongation rates, previously deduced from extensive measurements of elongations of cold-worked Zircaloy-2 pressure tubes in the Pickering reactors, have been modified to apply to the pressure tubes in the Douglas Point (DP) reactor by taking into account measured diffences in texture and dislocation density. Using these elongation rates, and structural data unique to the DP reactor, the analysis predicts elongation behaviour which is in good agreement with pressure tube elongations measured during the ten years of reactor operation. (Auth)

Stochastic model of template-directed elongation processes in biology.

Science.gov (United States)

Schilstra, Maria J; Nehaniv, Chrystopher L

2010-10-01

We present a novel modular, stochastic model for biological template-based linear chain elongation processes. In this model, elongation complexes (ECs; DNA polymerase, RNA polymerase, or ribosomes associated with nascent chains) that span a finite number of template units step along the template, one after another, with semaphore constructs preventing overtaking. The central elongation module is readily extended with modules that represent initiation and termination processes. The model was used to explore the effect of EC span on motor velocity and dispersion, and the effect of initiation activator and repressor binding kinetics on the overall elongation dynamics. The results demonstrate that (1) motors that move smoothly are able to travel at a greater velocity and closer together than motors that move more erratically, and (2) the rate at which completed chains are released is proportional to the occupancy or vacancy of activator or repressor binding sites only when initiation or activator/repressor dissociation is slow in comparison with elongation. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Translation Control of Swarming Proficiency in Bacillus subtilis by 5-Amino-pentanolylated Elongation Factor P.

Science.gov (United States)

Rajkovic, Andrei; Hummels, Katherine R; Witzky, Anne; Erickson, Sarah; Gafken, Philip R; Whitelegge, Julian P; Faull, Kym F; Kearns, Daniel B; Ibba, Michael

2016-05-20

Elongation factor P (EF-P) accelerates diprolyl synthesis and requires a posttranslational modification to maintain proteostasis. Two phylogenetically distinct EF-P modification pathways have been described and are encoded in the majority of Gram-negative bacteria, but neither is present in Gram-positive bacteria. Prior work suggested that the EF-P-encoding gene (efp) primarily supports Bacillus subtilis swarming differentiation, whereas EF-P in Gram-negative bacteria has a more global housekeeping role, prompting our investigation to determine whether EF-P is modified and how it impacts gene expression in motile cells. We identified a 5-aminopentanol moiety attached to Lys(32) of B. subtilis EF-P that is required for swarming motility. A fluorescent in vivo B. subtilis reporter system identified peptide motifs whose efficient synthesis was most dependent on 5-aminopentanol EF-P. Examination of the B. subtilis genome sequence showed that these EF-P-dependent peptide motifs were represented in flagellar genes. Taken together, these data show that, in B. subtilis, a previously uncharacterized posttranslational modification of EF-P can modulate the synthesis of specific diprolyl motifs present in proteins required for swarming motility. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Detecção de fatores de virulência de Escherichia coli e análise de Salmonella spp. em psitacídeos Detection of virulence factors in Escherichia coli and analysis of Salmonella spp. in psittacines

Directory of Open Access Journals (Sweden)

Isadora M. de O. Corrêa

2013-02-01

Full Text Available A flora entérica dos psitacídeos é composta principalmente por bactérias Gram positivas. Bactérias Gram negativas, como Escherichia coli e Salmonella spp., apresentam elevado potencial patogênico, sendo consideradas indicativo de problemas de manejo, que poderão culminar em manifestação de doenças em decorrência de fatores estressantes, dietas deficientes e superlotação, combinados com alta carga bacteriana no ambiente. O objetivo deste trabalho foi avaliar a presença de Salmonella spp., Escherichia coli e os fatores de virulência dos genes iss e iutA dos isolados de E. coli. Analisou-se um total de 44 amostras provenientes de psitacídeos criados em cativeiro, sendo estas 15 fragmentos de órgãos de aves submetidas a exame de necropsia e também 29 amostras de swabs de cloaca e inglúvio de papagaios-charão (Amazona pretrei criados em cativeiro. Nenhuma amostra foi positiva para Salmonella spp. Nas amostras de E. coli detectou-se ambos os fatores de virulência pesquisados.The enteric flora of psittacines is mainly composed of Gram positive bacteria. Gram negative bacteria, like Escherichia coli and Salmonella spp., have a high pathogenic potential and can be considerate as an indicative of management problems that may culminate in disease manifestation due to stress factors, poor diets and overcrowding, in combination with a high bacterial load on the environment. The objective of this study was evaluated the presence of Salmonella spp., Escherichia coli and the virulence genes iss and iutA from E. coli isolates. Forty-four samples were analyzed from psittacines living in captivity, which fifteen samples were from organs fragments of necropsied birds, and twenty-nine were from cloacal and crop swabs of red-spectacled parrots (Amazona pretrei keeping in captivity. No samples were positive for Salmonella spp. In the samples in which E. coli was detected, both virulence factors (genes iss and iutA were present.

ESBL-Producing Escherichia coli

DEFF Research Database (Denmark)

Hertz, Frederik Boetius

Urinary tract infection (UTI) is one the most common bacterial infections and is regularly treated in primary health care. The most common cause of UTI is extraintestinal pathogenic Escherichia coli (ExPEC) already present in the intestinal microflora, often as the dominating strain. Resistance...... in E.coli is increasing and especially isolates producing Extended-Spectrum Beta-Lactamases (ESBL) have been reported worldwide. Treatment of UTI is usually initiated by the general practitioners and a significant proportion of clinical isolates are now resistant to first line antibiotics. The global...... to investigate (i) antibiotics involved in selection of ESBL-producing E.coli, in an experimental mouse model in vivo, (ii) risk factors for UTI with ESBL-producing E.coli and (iii) to describe the phylogenetic composition of E.coli populations with different resistance patterns. We found that different...

Are Ichthyosporea animals or fungi? Bayesian phylogenetic analysis of elongation factor 1alpha of Ichthyophonus irregularis.

Science.gov (United States)

Ragan, Mark A; Murphy, Colleen A; Rand, Thomas G

2003-12-01

Ichthyosporea is a recently recognized group of morphologically simple eukaryotes, many of which cause disease in aquatic organisms. Ribosomal RNA sequence analyses place Ichthyosporea near the divergence of the animal and fungal lineages, but do not allow resolution of its exact phylogenetic position. Some of the best evidence for a specific grouping of animals and fungi (Opisthokonta) has come from elongation factor 1alpha, not only phylogenetic analysis of sequences but also the presence or absence of short insertions and deletions. We sequenced the EF-1alpha gene from the ichthyosporean parasite Ichthyophonus irregularis and determined its phylogenetic position using neighbor-joining, parsimony and Bayesian methods. We also sequenced EF-1alpha genes from four chytrids to provide broader representation within fungi. Sequence analyses and the presence of a characteristic 12 amino acid insertion strongly indicate that I. irregularis is a member of Opisthokonta, but do not resolve whether I. irregularis is a specific relative of animals or of fungi. However, the EF-1alpha of I. irregularis exhibits a two amino acid deletion heretofore reported only among fungi.

Nuclear starburst activity induced by elongated bulges in spiral galaxies

Science.gov (United States)

Kim, Eunbin; Kim, Sungsoo S.; Choi, Yun-Young; Lee, Gwang-Ho; de Grijs, Richard; Lee, Myung Gyoon; Hwang, Ho Seong

2018-06-01

We study the effects of bulge elongation on the star formation activity in the centres of spiral galaxies using the data from the Sloan Digital Sky Survey Data Release 7. We construct a volume-limited sample of face-on spiral galaxies with Mr nuclear starbursts using the fibre specific star formation rates derived from the SDSS spectra. We find a statistically significant correlation between bulge elongation and nuclear starbursts in the sense that the fraction of nuclear starbursts increases with bulge elongation. This correlation is more prominent for fainter and redder galaxies, which exhibit higher ratios of elongated bulges. We find no significant environmental dependence of the correlation between bulge elongation and nuclear starbursts. These results suggest that non-axisymmetric bulges can efficiently feed the gas into the centre of galaxies to trigger nuclear starburst activity.

A case of abdominal compartment syndrome derived from simple elongated sigmoid colon in an elderly man

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Masaaki Shida

2016-01-01

Discussion and conclusion: Considering the increase in the aging population, we must bear in mind that abdominal compartment syndrome may occur in simple elongated sigmoid colon without other risk factors.

Characterization of the domains of E. coli initiation factor IF2 responsible for recognition of the ribosome

DEFF Research Database (Denmark)

Manuel Palacios Moreno, Juan; Andersen, Lars Dyrskjøt; Egebjerg Kristensen, Janni

1999-01-01

We have studied the interactions between the ribosome and the domains of Escherichia coli translation initiation factor 2, using an in vitro ribosomal binding assay with wild-type forms, N- and C-terminal truncated forms of IF2 as well as isolated structural domains. A deletion mutant of the fact...

The 7SK snRNP associates with the little elongation complex to promote snRNA gene expression.

Science.gov (United States)

Egloff, Sylvain; Vitali, Patrice; Tellier, Michael; Raffel, Raoul; Murphy, Shona; Kiss, Tamás

2017-04-03

The 7SK small nuclear RNP (snRNP), composed of the 7SK small nuclear RNA (snRNA), MePCE, and Larp7, regulates the mRNA elongation capacity of RNA polymerase II (RNAPII) through controlling the nuclear activity of positive transcription elongation factor b (P-TEFb). Here, we demonstrate that the human 7SK snRNP also functions as a canonical transcription factor that, in collaboration with the little elongation complex (LEC) comprising ELL, Ice1, Ice2, and ZC3H8, promotes transcription of RNAPII-specific spliceosomal snRNA and small nucleolar RNA (snoRNA) genes. The 7SK snRNA specifically associates with a fraction of RNAPII hyperphosphorylated at Ser5 and Ser7, which is a hallmark of RNAPII engaged in snRNA synthesis. Chromatin immunoprecipitation (ChIP) and chromatin isolation by RNA purification (ChIRP) experiments revealed enrichments for all components of the 7SK snRNP on RNAPII-specific sn/snoRNA genes. Depletion of 7SK snRNA or Larp7 disrupts LEC integrity, inhibits RNAPII recruitment to RNAPII-specific sn/snoRNA genes, and reduces nascent snRNA and snoRNA synthesis. Thus, through controlling both mRNA elongation and sn/snoRNA synthesis, the 7SK snRNP is a key regulator of nuclear RNA production by RNAPII. © 2017 The Authors.

Celulitis in Japanese Quails (coturnix coturnix japonica for Eschorichia coli: virulence factors, sensibility and profile antimicrobial resistance /Celulite em codornas (coturnix coturnix japonica causada por Escherichia coli: fatores de virulência, sensibilidade e perfil de resistência antimicrobiana

Directory of Open Access Journals (Sweden)

Marilda Carlos Vidotto

2000-12-01

Full Text Available Ten E. coli strains isolated from celulitis lesion s of Japanese quails were to evaluated antimicrobia l resistance to twent y six drugs , to pathogenicity of strains in SPF chickens embryonated eggs and virulence factors. The antimicrobials of higher efficiency wer e ampicillin, florfenicol and the lesser efficiency were erythromycin, oxacilin, lincomicin, novobiocin, penicillin, sulfonamidas, trimethoprim+sulfomethoxazo/e and tetracyicline. The majority of E. coli strains were serum resistance, the others virulence factors, hemolisin and congo red affinity, were lesser frequent on the studied strains. Pathogenicity of E. coli strains, evaluated to DL50 in embryonated eggs, had varied of 8x10 2 the 3,2x10.Dez cepas de E. coli isoladas de lesões de celulite em codornas foram avaliadas quanto a resistência antimicrobiana frente a vinte e seis drogas, a patogenicidade das amostras em ovos embrionários de galinha SPF e quanto aos fatores de virulência: hemolisinas, resistência sérica e afinidade ao vermelho congo Os antimicrobianos de maior eficiência foram ampicilinar florfenicol e os menos eficientes foram eritromicina, oxacilina. lincomicina, novobiocina. penicsilna, sulfonamida, sulfomethoxazole+ trimetoprim e tetraciclina. A maioria das amostras de E. coli foram resistentes ao soro, os outros fatores do virulência, hemolisina e afinidade ao vermelho-congo, foram menos freqüentes nas amostras estudadas. A patogenicidade das amostras de E. coli estimada através da DL50 em ovos embrionados, variaram de 8x10* a 3.2x10a.

Contactless Measurement Of Rectilinearity Of An Elongated Object Based On The Example A Crane Rail

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Ćmielewski Kazimierz

2015-07-01

Full Text Available The common aim of engineering surveys is to determine deviations from rectilinearity for elongated objects. We have developed a number of methods for measuring points that represent an elongated object. These are the constant straight (optical, laser, mechanical-string method, the trigonometric method, geometric levelling method, photogrammetric methods and terrestrial laser scanning. When taking these measurements, it is crucial to have a direct access to the survey points of the measured object. Factors impeding the measurements include: adverse lighting conditions, vibration, dust, refractory effects, lack of direct access to the survey points, etc.

FtsZ-Dependent Elongation of a Coccoid Bacterium

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Ana R. Pereira

2016-09-01

Full Text Available A mechanistic understanding of the determination and maintenance of the simplest bacterial cell shape, a sphere, remains elusive compared with that of more complex shapes. Cocci seem to lack a dedicated elongation machinery, and a spherical shape has been considered an evolutionary dead-end morphology, as a transition from a spherical to a rod-like shape has never been observed in bacteria. Here we show that a Staphylococcus aureus mutant (M5 expressing the ftsZG193D allele exhibits elongated cells. Molecular dynamics simulations and in vitro studies indicate that FtsZG193D filaments are more twisted and shorter than wild-type filaments. In vivo, M5 cell wall deposition is initiated asymmetrically, only on one side of the cell, and progresses into a helical pattern rather than into a constricting ring as in wild-type cells. This helical pattern of wall insertion leads to elongation, as in rod-shaped cells. Thus, structural flexibility of FtsZ filaments can result in an FtsZ-dependent mechanism for generating elongated cells from cocci.

Fluoroquinolone-resistant Escherichia coli carriage in long-term care facility.

Science.gov (United States)

Maslow, Joel N; Lee, Betsy; Lautenbach, Ebbing

2005-06-01

We conducted a cross-sectional study to determine the prevalence of, and risk factors for, colonization with fluoroquinolone (FQ)-resistant Escherichia coli in residents in a long-term care facility. FQ-resistant E. coli were identified from rectal swabs for 25 (51%) of 49 participants at study entry. On multivariable analyses, prior FQ use was the only independent risk factor for FQ-resistant E. coli carriage and was consistent for FQ exposures in the previous 3, 6, 9, or 12 months. Pulsed-field gel electrophoresis of FQ-resistant E. coli identified clonal spread of 1 strain among 16 residents. Loss (6 residents) or acquisition (7 residents) of FQ-resistant E. coli was documented and was associated with de novo colonization with genetically distinct strains. Unlike the case in the hospital setting, FQ-resistant E. coli carriage in long-term care facilities is associated with clonal spread.

A cross-sectional study examining the prevalence and risk factors for anti-microbial-resistant generic Escherichia coli in domestic dogs that frequent dog parks in three cities in south-western Ontario, Canada.

Science.gov (United States)

Procter, T D; Pearl, D L; Finley, R L; Leonard, E K; Janecko, N; Reid-Smith, R J; Weese, J S; Peregrine, A S; Sargeant, J M

2014-06-01

Anti-microbial resistance can threaten health by limiting treatment options and increasing the risk of hospitalization and severity of infection. Companion animals can shed anti-microbial-resistant bacteria that may result in the exposure of other dogs and humans to anti-microbial-resistant genes. The prevalence of anti-microbial-resistant generic Escherichia coli in the faeces of dogs that visited dog parks in south-western Ontario was examined and risk factors for shedding anti-microbial-resistant generic E. coli identified. From May to August 2009, canine faecal samples were collected at ten dog parks in three cities in south-western Ontario, Canada. Owners completed a questionnaire related to pet characteristics and management factors including recent treatment with antibiotics. Faecal samples were collected from 251 dogs, and 189 surveys were completed. Generic E. coli was isolated from 237 of the faecal samples, and up to three isolates per sample were tested for anti-microbial susceptibility. Eighty-nine percent of isolates were pan-susceptible; 82.3% of dogs shed isolates that were pan-susceptible. Multiclass resistance was detected in 7.2% of the isolates from 10.1% of the dogs. Based on multilevel multivariable logistic regression, a risk factor for the shedding of generic E. coli resistant to ampicillin was attending dog day care. Risk factors for the shedding of E. coli resistant to at least one anti-microbial included attending dog day care and being a large mixed breed dog, whereas consumption of commercial dry and home cooked diets was protective factor. In a multilevel multivariable model for the shedding of multiclass-resistant E. coli, exposure to compost and being a large mixed breed dog were risk factors, while consumption of a commercial dry diet was a sparing factor. Pet dogs are a potential reservoir of anti-microbial-resistant generic E. coli; some dog characteristics and management factors are associated with the prevalence of anti

Fatores de virulência em linhagens de Escherichia coli isoladas de mastite bovina Virulence factors in Escherichia coli strains isolated from bovine mastitis

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M.G. Ribeiro

2006-10-01

Full Text Available Avaliou-se a ocorrência de fatores de virulência e do sorotipo O157:H7 em 120 linhagens de Escherichia coli, isoladas de 80 casos de mastite clínica bovina e 40 de mastite subclínica. Verificou-se alfa-hemolisina em oito (6,7% linhagens, isoladas de cinco casos de mastite clínica e três de mastite subclínica e em nenhuma das estirpes detectou-se enteroemolisina. A presença de sideróforos foi encontrada em 11 (9,2% linhagens, sete de mastite clínica e quatro de subclínica. Em duas (1,7% estirpes isoladas de mastite subclínica, identificou-se enterotoxina STa. Observou-se efeito citopático em células vero compatível com a produção de verotoxina-VT em cinco (4,2% linhagens, duas de mastite clínica e três subclínicas. Em uma (0,8% linhagem isolada de mastite clínica, detectou-se efeito citopático compatível com o fator necrosante citotóxico. Nenhuma estirpe apresentou-se sorbitol-negativa no MacConkey-sorbitol, tampouco aglutinou com o sorotipo O157:H7. Os antimicrobianos mais efetivos foram polimixina B (97,5% e norfloxacina (95,8%. Observou-se multi-resistência a dois ou mais antimicrobianos em 24 (20% estirpes, principalmente com o uso de ampicilina e ceftiofur.The occurrence of different virulence factors and O157:H7 serotype investigation in 120 Escherichia coli strains isolated from clinical (80 cases and subclinical (40 cases bovine mastitis was evaluated. Alpha-haemolysin was detected in 8 (6.7% strains (5 clinical and 3 subclinical cases. None strain showed enterohaemolysin production. E. coli growth under iron restriction conditions (siderophores production was observed in 11 (9.2% strains (7 clinical and 4 subclinical cases. STa enterotoxin was detected in 2 (1.7% strains from subclinical cases. Cytotoxic effect in vero cells compatible with verotoxin-VT production was observed in 5 (4.2% strains (2 clinical and 3 subclinical cases. One strain (0.8% isolated from clinical mastitis showed cytophatic effect in vero

Mechanism of SOS-induced targeted and untargeted mutagenesis in E. coli

International Nuclear Information System (INIS)

Maenhaut-Michel, G.

1985-01-01

This paper retraces the evolution of hypotheses concerning mechanisms of SOS induced mutagenesis. Moreover, it reports some recent data which support a new model for the mechanism of targeted and untargeted mutagenesis in E. coli. In summary, the SOS mutator effect, which is responsible for untargeted mutagenesis and perhaps for the misincorporation step in targeted mutagenesis, is believed to involve a fidelity function associated with DNA polymerase III and does not require the umuC gene product. umuC and umuD gene products are probably required specifically for elongation of DNA synthesis past blocking lesions, i.e. to allow mutagenic replication of damaged DNA

Influence of Gradual Elongation to the Patella Tendon Insertion in Rabbits

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Hirotaka Mutsuzaki

2014-08-01

Full Text Available The purpose of this study was to examine the histological changes at the patella tendon (PT insertion site under gradual elongation in rabbits. Gradual elongation of the PT was performed using external fixation for 4 weeks, with a lengthening speed of 0.5 mm/day (elongation group; n = 24. Rabbits in the sham group underwent the same surgical procedure without gradual elongation (sham group; n = 24. Eight animals were sacrificed 1, 2 and 4 weeks after surgery in each group, respectively. Average thicknesses of stained glycosaminoglycan (GAGs areas by Safranin-O staining in the total cartilage layer and the uncalcified fibrocartilage layer in the elongation group were significantly higher than that in the sham group at 4 weeks (p < 0.05 and that in the intact PT group (n = 6, p < 0.05. In the elongation group, the peak in the average thicknesses of the stained GAGs areas in the total cartilage layer and the uncalcified fibrocartilage layer were observed at 4 weeks. Gradual elongation of PT insertion significantly affected the increase in the average thicknesses of the stained GAGs areas in the cartilage layer especially in the uncalcified fibrocartilage layer at 4 weeks in rabbits. Clinically, insertions of tendon and ligament can extend during gradual elongation using external fixation more than 4 weeks after the operation.

Tree-shoot elongation patterns in a gamma-irradiated northern forest community

International Nuclear Information System (INIS)

Buech, R.R.; Salmonson, B.J.

1977-01-01

Shoot elongation in the upper crowns of seven tree species was studied in a gamma-irradiated northern forest community near Rhinelander, Wis. Observations on the pattern and duration of shoot elongation are presented for the irradiation (1972) and postirradiation (1973) growing seasons. The gymnosperm Abies balsamea was the most radiosensitive species. Significant alteration in pattern and duration was observed in 1973 at exposure rates of 4 to 25 r/20-hr day; 31 r/20-hr day was lethal. At the other extreme, 116 r/20-hr day produced no significant effects on Acer saccharum shoot elongation pattern or duration. Acer rubrum, Betula papyrifera, Populus tremuloides, Quercus rubra, and Tilia americana were intermediate in radiosensitivity. Observed responses to radiation were alteration in the elongation pattern, suppression of internodal elongation, and death. Effects of the 1972 growing-season exposure were most obvious in the subsequent growing seasons. Retardation of initial elongation was characteristic of all species. Cessation of elongation was variable, even within species (e.g., P. tremuloides). The results suggest that bud differentiation and morphology and dependency on food reserves contributed to the lag in manifestation of radiation damage. The resultant crown characteristics are described and explained

Experimental induced avian E. coli salpingitis

DEFF Research Database (Denmark)

Olsen, Rikke Heidemann; Thøfner, Ida; Pors, Susanne Elisabeth

2016-01-01

Several types of Escherichia coli have been associated with extra-intestinal infections in poultry, however, they may vary significantly in their virulence potential. The aim of the present study was to investigate the virulence of five strains of E. coli obtained from different disease......) had a distinct ability to cause disease. Results of the study shows major differences in virulence of different strains of E. coli in ascending infections; however, there was no indication of tissue-specific adaptation, since strains obtained from lesions unrelated to the reproductive system were...... fully capable of causing experimental infection. In conclusion, the study provides evidence for the clinical outcome of infection with E. coli in poultry is largely influenced by the specific strain as well as individual host factors....

Antimicrobial susceptibility, risk factors and prevalence of bla cefotaximase, temoneira, and sulfhydryl variable genes among Escherichia coli in community-acquired pediatric urinary tract infection.

Science.gov (United States)

Nisha, Kallyadan V; Veena, Shetty A; Rathika, Shenoy D; Vijaya, Shenoy M; Avinash, Shetty K

2017-01-01

The emergence of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli has become an important challenge among pediatric patients with community-acquired urinary tract infection (UTI). The aim of this study was to assess the antimicrobial susceptibility patterns, associated risk factors and to survey the frequency of bla cefotaximase (CTX-M), bla temoneira (TEM), and bla sulfhydryl variable (SHV) genotypes in ESBL-producing E. coli isolated from children with community-acquired UTI. This was a prospective study conducted from November 2012 to March 2016 in a tertiary care center. E. coli isolated in urine cultures from children aged ≤18 years was identified and confirmed for ESBL production. ESBL-positive strains were screened for ESBL encoding genes. Chi-square test and Fisher's exact test were used to compare the difference in antibiotic susceptibility with respect to ESBL positive and negative, and binary logistic regression was used to identify the risk factors associated with ESBL production. Among 523 E. coli isolates, 196 (37.5%) were ESBL positive, >90% were resistant to cephalosporins, and 56% were resistant to fluoroquinolones. Least resistance was observed for imipenem, netilmicin, and nitrofurantoin (2%, 8.6%, 15.3%). Association between ESBL production and drug resistance was significant for ceftazidime ( P antibiotics were the common risk factors. ESBL-producing E. coli from community-acquired pediatric UTI carries more than one type of beta-lactamase coding genes correlating their increased antibiotic resistance. Aggressive infection control policy, routine screening for detecting ESBL isolates in clinical samples, and antimicrobial stewardship are the keys to prevent their dissemination in community settings.

Environmental and genetic factors affecting mutability to aminoglycoside antibiotics among Escherichia coli K12 strains

Directory of Open Access Journals (Sweden)

Monteiro A.C.M.

2003-01-01

Full Text Available Environmental and genetic factors affecting the in vitro spontaneous mutation frequencies to aminoglycoside resistance in Escherichia coli K12 were investigated. Spontaneous mutation frequencies to kanamycin resistance were at least 100 fold higher on modified Luria agar (L2 plates, when compared to results obtained in experiments carried out with Nutrient agar (NA plates. In contrast to rifampincin, the increased mutability to kanamycin resistance could not be attributed to a mutator phenotype expressed by DNA repair defective strains. Kanamycin mutant selection windows and mutant preventive concentrations on L2 plates were at least fourfold higher than on NA plates, further demonstrating the role of growth medium composition on the mutability to aminoglycosides. Mutability to kanamycin resistance was increased following addition of sorbitol, suggesting that osmolarity is involved on the spontaneous mutability of E. coli K12 strains to aminoglycosides. The spontaneous mutation rates to kanamycin resistance on both L2 and NA plates were strictly associated with the selective antibiotic concentrations. Moreover, mutants selected at different antibiotic concentrations expressed heterogeneous resistance levels to kanamycin and most of them expressing multiple resistance to all tested aminoglycoside antibiotics (gentamicin, neomycin, amykacin and tobramycin. These results will contribute to a better understanding of the complex nature of aminoglycoside resistance and the emergence of spontaneous resistant mutants among E. coli K12 strains.

Mutual interdependence of splicing and transcription elongation.

Science.gov (United States)

Brzyżek, Grzegorz; Świeżewski, Szymon

2015-01-01

Transcription and splicing are intrinsically linked, as splicing needs a pre-mRNA substrate to commence. The more nuanced view is that the rate of transcription contributes to splicing regulation. On the other hand there is accumulating evidence that splicing has an active role in controlling transcription elongation by DNA-dependent RNA polymerase II (RNAP II). We briefly review those mechanisms and propose a unifying model where splicing controls transcription elongation to provide an optimal timing for successive rounds of splicing.

Bacillus anthracis Prolyl 4-Hydroxylase Interacts with and Modifies Elongation Factor Tu

Energy Technology Data Exchange (ETDEWEB)

Schnicker, Nicholas J. [Department; Razzaghi, Mortezaali [Department; Guha Thakurta, Sanjukta [Department; Chakravarthy, Srinivas [Biophysics; Dey, Mishtu [Department

2017-10-17

Prolyl hydroxylation is a very common post-translational modification and plays many roles in eukaryotes such as collagen stabilization, hypoxia sensing, and controlling protein transcription and translation. There is a growing body of evidence that suggests that prokaryotes contain prolyl 4-hydroxylases (P4Hs) homologous to the hypoxia-inducible factor (HIF) prolyl hydroxylase domain (PHD) enzymes that act on elongation factor Tu (EFTu) and are likely involved in the regulation of bacterial translation. Recent biochemical and structural studies with a PHD from Pseudomonas putida (PPHD) determined that it forms a complex with EFTu and hydroxylates a prolyl residue of EFTu. Moreover, while animal, plant, and viral P4Hs act on peptidyl proline, most prokaryotic P4Hs have been known to target free l-proline; the exceptions include PPHD and a P4H from Bacillus anthracis (BaP4H) that modifies collagen-like proline-rich peptides. Here we use biophysical and mass spectrometric methods to demonstrate that BaP4H recognizes full-length BaEFTu and a BaEFTu 9-mer peptide for site-specific proline hydroxylation. Using size-exclusion chromatography coupled small-angle X-ray scattering (SEC–SAXS) and binding studies, we determined that BaP4H forms a 1:1 heterodimeric complex with BaEFTu. The SEC–SAXS studies reveal dissociation of BaP4H dimeric subunits upon interaction with BaEFTu. While BaP4H is unusual within bacteria in that it is structurally and functionally similar to the animal PHDs and collagen P4Hs, respectively, this work provides further evidence of its promiscuous substrate recognition. It is possible that the enzyme might have evolved to hydroxylate a universally conserved protein in prokaryotes, similar to the PHDs, and implies a functional role in B. anthracis.

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

Mechanical modelling quantifies the functional importance of outer tissue layers during root elongation and bending

Science.gov (United States)

Dyson, Rosemary J; Vizcay-Barrena, Gema; Band, Leah R; Fernandes, Anwesha N; French, Andrew P; Fozard, John A; Hodgman, T Charlie; Kenobi, Kim; Pridmore, Tony P; Stout, Michael; Wells, Darren M; Wilson, Michael H; Bennett, Malcolm J; Jensen, Oliver E

2014-01-01

Root elongation and bending require the coordinated expansion of multiple cells of different types. These processes are regulated by the action of hormones that can target distinct cell layers. We use a mathematical model to characterise the influence of the biomechanical properties of individual cell walls on the properties of the whole tissue. Taking a simple constitutive model at the cell scale which characterises cell walls via yield and extensibility parameters, we derive the analogous tissue-level model to describe elongation and bending. To accurately parameterise the model, we take detailed measurements of cell turgor, cell geometries and wall thicknesses. The model demonstrates how cell properties and shapes contribute to tissue-level extensibility and yield. Exploiting the highly organised structure of the elongation zone (EZ) of the Arabidopsis root, we quantify the contributions of different cell layers, using the measured parameters. We show how distributions of material and geometric properties across the root cross-section contribute to the generation of curvature, and relate the angle of a gravitropic bend to the magnitude and duration of asymmetric wall softening. We quantify the geometric factors which lead to the predominant contribution of the outer cell files in driving root elongation and bending. PMID:24641449

Evolution and Allometry of Calcaneal Elongation in Living and Extinct Primates

Science.gov (United States)

Boyer, Doug M.; Seiffert, Erik R.; Gladman, Justin T.; Bloch, Jonathan I.

2013-01-01

Specialized acrobatic leaping has been recognized as a key adaptive trait tied to the origin and subsequent radiation of euprimates based on its observed frequency in extant primates and inferred frequency in extinct early euprimates. Hypothesized skeletal correlates include elongated tarsal elements, which would be expected to aid leaping by allowing for increased rates and durations of propulsive acceleration at takeoff. Alternatively, authors of a recent study argued that pronounced distal calcaneal elongation of euprimates (compared to other mammalian taxa) was related primarily to specialized pedal grasping. Testing for correlations between calcaneal elongation and leaping versus grasping is complicated by body size differences and associated allometric affects. We re-assess allometric constraints on, and the functional significance of, calcaneal elongation using phylogenetic comparative methods, and present an evolutionary hypothesis for the evolution of calcaneal elongation in primates using a Bayesian approach to ancestral state reconstruction (ASR). Results show that among all primates, logged ratios of distal calcaneal length to total calcaneal length are inversely correlated with logged body mass proxies derived from the area of the calcaneal facet for the cuboid. Results from phylogenetic ANOVA on residuals from this allometric line suggest that deviations are explained by degree of leaping specialization in prosimians, but not anthropoids. Results from ASR suggest that non-allometric increases in calcaneal elongation began in the primate stem lineage and continued independently in haplorhines and strepsirrhines. Anthropoid and lorisid lineages show stasis and decreasing elongation, respectively. Initial increases in calcaneal elongation in primate evolution may be related to either development of hallucal-grasping or a combination of grasping and more specialized leaping behaviors. As has been previously suggested, subsequent increases in calcaneal

ANALISIS CEMARAN BAKTERI Escherichia coli ANALISIS CEMARAN BAKTERI Escherichia coli ANALISIS CEMARAN BAKTERI Escherichia coli

OpenAIRE

ANGGREINI, RAHAYU

2015-01-01

2015 RAHAYU ANGGREINI coli Penelitian ini bertujuan untuk melakukan identifikasi cemaran bakteri E. coli O157:H7 pada daging sapi di kota Makassar. Sampel pada penelitian ini sebanyak 72 sampel Kata Kunci : Daging sapi, pasar tradisional, E. coli, E. coli O157:H7, kontaminasi bakteri, identifikasi E. coli O157:H7.

QTL analysis of internode elongation in response to gibberellin in deepwater rice

OpenAIRE

Nagai, Keisuke; Kondo, Yuma; Kitaoka, Takuya; Noda, Tomonori; Kuroha, Takeshi; Angeles-Shim, Rosalyn B.; Yasui, Hideshi; Yoshimura, Atsushi; Ashikari, Motoyuki

2014-01-01

Gibberellin (GA) is a plant hormone that has important roles in numerous plant developmental phases. Rice plants known as deepwater rice respond to flooding by elongating their internodes to avoid anoxia. Previous studies reported that GA is essential for internode elongation in deepwater rice. Quantitative trait locus (QTL) analyses identified QTLs regulating internode elongation in response to deepwater conditions. However, the interaction between internode elongation and regulators of GA s...

Comparative Study of the Life Cycle Dependent Post-Translation Modifications of Protein Synthesis Elongation Factor Tu Present in the Membrane Proteome of Streptomycetes and Mycobacteria

Czech Academy of Sciences Publication Activity Database

Holub, Martin; Bezoušková, Silvia; Petráčková, Denisa; Kalachová, Ladislava; Kofroňová, Olga; Benada, Oldřich; Weiser, Jaroslav

2010-01-01

Roč. 55, č. 3 (2010), s. 203-210 ISSN 0015-5632 R&D Projects: GA AV ČR IAA600200702; GA AV ČR IAA500200913 Institutional research plan: CEZ:AV0Z50200510 Keywords : ESCHERICHIA-COLI * COELICOLOR A3(2) * OUTER-MEMBRANE Subject RIV: EE - Microbiology, Virology Impact factor: 0.977, year: 2010

Gibberellin biosynthesis and signal transduction is essential for internode elongation in deepwater rice.

Science.gov (United States)

Ayano, Madoka; Kani, Takahiro; Kojima, Mikiko; Sakakibara, Hitoshi; Kitaoka, Takuya; Kuroha, Takeshi; Angeles-Shim, Rosalyn B; Kitano, Hidemi; Nagai, Keisuke; Ashikari, Motoyuki

2014-10-01

Under flooded conditions, the leaves and internodes of deepwater rice can elongate above the water surface to capture oxygen and prevent drowning. Our previous studies showed that three major quantitative trait loci (QTL) regulate deepwater-dependent internode elongation in deepwater rice. In this study, we investigated the age-dependent internode elongation in deepwater rice. We also investigated the relationship between deepwater-dependent internode elongation and the phytohormone gibberellin (GA) by physiological and genetic approach using a QTL pyramiding line (NIL-1 + 3 + 12). Deepwater rice did not show internode elongation before the sixth leaf stage under deepwater condition. Additionally, deepwater-dependent internode elongation occurred on the sixth and seventh internodes during the sixth leaf stage. These results indicate that deepwater rice could not start internode elongation until the sixth leaf stage. Ultra-performance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS) method for the phytohormone contents showed a deepwater-dependent GA1 and GA4 accumulation in deepwater rice. Additionally, a GA inhibitor abolished deepwater-dependent internode elongation in deepwater rice. On the contrary, GA feeding mimicked internode elongation under ordinary growth conditions. However, mutations in GA biosynthesis and signal transduction genes blocked deepwater-dependent internode elongation. These data suggested that GA biosynthesis and signal transduction are essential for deepwater-dependent internode elongation in deepwater rice. © 2014 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.

Epidemiology and Characteristics of Escherichia coli Sequence Type 131 (ST131) from Long-Term Care Facility Residents Colonized Intestinally with Fluoroquinolone-Resistant Escherichia coli

Science.gov (United States)

Han, Jennifer H.; Garrigan, Charles; Johnston, Brian; Nachamkin, Irving; Clabots, Connie; Bilker, Warren B.; Santana, Evelyn; Tolomeo, Pam; Maslow, Joel; Myers, Janice; Carson, Lesley; Lautenbach, Ebbing; Johnson, James R.

2016-01-01

The objective of this study was to evaluate molecular and epidemiologic factors associated with Escherichia coli sequence type 131 (ST131) among long-term care facility (LTCF) residents who acquired gastrointestinal tract colonization with fluoroquinolone-resistant E. coli (FQREC). Colonizing isolates from 37 residents who newly developed FQREC colonization at three LTCFs from 2006–2008 were evaluated. Twenty-nine (78%) of 37 total FQREC colonizing isolates were ST131. Most ST131 isolates had a distinctive combination of gyrA and parC replacement mutations. The ST131 and non-ST131 isolates differed significantly for the prevalence of many individual virulence factors but not for the proportion that qualified molecularly as extraintestinal pathogenic E. coli (ExPEC) or aggregate virulence factor scores. E. coli ST131 was highly prevalent among LTCF residents with FQREC colonization. Future studies should determine the risk factors for infection among ST131-colonized residents, and assess the potential for increased transmissibility of ST131 in the long-term care setting. PMID:27939288

Microbiological water quality of Igapó Lake Londrina - PR and genotypic characterization of virulence factors associated with enteropathogenic Escherichia coli (EPEC and Shiga toxin-producing E. coli (STEC

Directory of Open Access Journals (Sweden)

Paulo Alfonso Schuroff

2014-12-01

Full Text Available This work aimed at the detection and quantification of Total Coliforms and Escherichia coli in Igapó Lake, in order to evaluate the quality of these waters as proper or unfit for recreation, in addition to the genotypic characterization of virulence factors associated with EPEC and STEC by PCR. The study area was the Igapó Lake I, II, III and IV. Samples were collected monthly from March 2011 to February 2012. The technique used for the detection and quantification of Total Coliforms and E. coli was the Colilert chromogenic substrate. In the technique of PCR, the eae and bfp genes were tested to characterize the typical EPEC pathotype; stx1, stx2, eae and hlyA the STEC pathotype and the samples that presented only the eae gene were characterized as atypical EPEC. According to CONAMA Resolution 357/2005, it has been observed that only Igapó Lake III was rated inappropriate for primary contact recreation, while for secondary contact recreation, all lakes were considered appropriate. Moreover, a strong relationship between rainfall and E. coli indices in Igapó Lake can be observed, which in dry months the quantity drastically decreases, while in rainy months the opposite relationship was observed. Of the 97 strains of E. coli isolated, two had the eae gene (atypical EPEC. None of the isolates contained genes stx1, stx2, bfp and hlyA. Thus, we hope to educate the population and public agencies of the importance of microbiological monitoring of recreational waters to prevent outbreaks of waterborne infections.

Mammalian translation elongation factor eEF1A2: X-ray structure and new features of GDP/GTP exchange mechanism in higher eukaryotes.

Science.gov (United States)

Crepin, Thibaut; Shalak, Vyacheslav F; Yaremchuk, Anna D; Vlasenko, Dmytro O; McCarthy, Andrew; Negrutskii, Boris S; Tukalo, Michail A; El'skaya, Anna V

2014-11-10

Eukaryotic elongation factor eEF1A transits between the GTP- and GDP-bound conformations during the ribosomal polypeptide chain elongation. eEF1A*GTP establishes a complex with the aminoacyl-tRNA in the A site of the 80S ribosome. Correct codon-anticodon recognition triggers GTP hydrolysis, with subsequent dissociation of eEF1A*GDP from the ribosome. The structures of both the 'GTP'- and 'GDP'-bound conformations of eEF1A are unknown. Thus, the eEF1A-related ribosomal mechanisms were anticipated only by analogy with the bacterial homolog EF-Tu. Here, we report the first crystal structure of the mammalian eEF1A2*GDP complex which indicates major differences in the organization of the nucleotide-binding domain and intramolecular movements of eEF1A compared to EF-Tu. Our results explain the nucleotide exchange mechanism in the mammalian eEF1A and suggest that the first step of eEF1A*GDP dissociation from the 80S ribosome is the rotation of the nucleotide-binding domain observed after GTP hydrolysis. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

Is epidermal growth factor involved in development of duodenal polyps in familial polyposis coli?

DEFF Research Database (Denmark)

Poulsen, Steen Seier

1988-01-01

Duodenal adenomas are a frequent extracolonic manifestation in patients with familial polyposis coli (FPC). Epidermal growth factor (EGF), a polypeptide that stimulates cellular growth and differentiation, is localized in Paneth cells in the small intestine. In two patients with FPC, we found EGF...... immunoreactivity in duodenal adenomas. Numerous EGF immunoreactive Paneth cells were localized, not as usually, in the bottom of the crypts, but scattered along the crypts alone or in clusters. We do not know whether EGF is involved in the development of duodenal polyps in FPC patients, or whether the present...

Roles of Protein Synthesis Elongation Factor EF-Tu in Heat Tolerance in Plants

Directory of Open Access Journals (Sweden)

Jianming Fu

2012-01-01

Full Text Available EF-Tu proteins of plastids, mitochondria, and the cytosolic counterpart EF-1α in plants, as well as EF-Tu proteins of bacteria, are highly conserved and multifunctional. The functions of EF-Tu include transporting the aminoacyl-tRNA complex to the A site of the ribosome during protein biosynthesis; chaperone activity in protecting other proteins from aggregation caused by environmental stresses, facilitating renaturation of proteins when conditions return to normal; displaying a protein disulfide isomerase activity; participating in the degradation of N-terminally blocked proteins by the proteasome; eliciting innate immunity and triggering resistance to pathogenic bacteria in plants; participating in transcription when an E. coli host is infected with phages. EF-Tu genes are upregulated by abiotic stresses in plants, and EF-Tu plays important role in stress responses. Expression of a plant EF-Tu gene confers heat tolerance in E. coli, maize knock-out EF-Tu null mutants are heat susceptible, and over-expression of an EF-Tu gene improves heat tolerance in crop plants. This review paper summarizes the current knowledge of EF-Tu proteins in stress responses in plants and progress on application of EF-Tu for developing crop varieties tolerant to abiotic stresses, such as high temperatures.

Transition zone cells reach G2 phase before initiating elongation in maize root apex

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M. Victoria Alarcón

2017-06-01

Full Text Available Root elongation requires cell divisions in the meristematic zone and cell elongation in the elongation zone. The boundary between dividing and elongating cells is called the transition zone. In the meristem zone, initial cells are continuously dividing, but on the basal side of the meristem cells exit the meristem through the transition zone and enter in the elongation zone, where they stop division and rapidly elongate. Throughout this journey cells are accompanied by changes in cell cycle progression. Flow cytometry analysis showed that meristematic cells are in cycle, but exit when they enter the elongation zone. In addition, the percentage of cells in G2 phase (4C strongly increased from the meristem to the elongation zone. However, we did not observe remarkable changes in the percentage of cells in cell cycle phases along the entire elongation zone. These results suggest that meristematic cells in maize root apex stop the cell cycle in G2 phase after leaving the meristem.

Infectious endocarditis caused by Escherichia coli

DEFF Research Database (Denmark)

Lauridsen, Trine Kiilerich; Arpi, Magnus; Fritz-Hansen, Thomas

2011-01-01

Although Escherichia coli is among the most common causes of Gram-negative bacteraemia, infectious endocarditis (IE) due to this pathogen is rare. A 67-y-old male without a previous medical history presented with a new mitral regurgitation murmur and persisting E. coli bacteraemia in spite of broad......-spectrum intravenous antibiotics. Transthoracic and transoesophageal echocardiography revealed a severe mitral endocarditis. E. coli DNA was identified from the mitral valve and the vegetation, and no other pathogen was found. The case was further complicated by spondylodiscitis and bilateral endophthalmitis. Extra......-intestinal pathogenic E. coli (ExPEC) are able to colonize tissue outside the gastrointestinal tract and contain a variety of virulence factors that may enable the pathogens to invade and induce infections in the cardiac endothelia. In these cases echocardiography as the imaging technology is of paramount importance...

Adenylate cyclase regulates elongation of mammalian primary cilia

International Nuclear Information System (INIS)

Ou, Young; Ruan, Yibing; Cheng, Min; Moser, Joanna J.; Rattner, Jerome B.; Hoorn, Frans A. van der

2009-01-01

The primary cilium is a non-motile microtubule-based structure that shares many similarities with the structures of flagella and motile cilia. It is well known that the length of flagella is under stringent control, but it is not known whether this is true for primary cilia. In this study, we found that the length of primary cilia in fibroblast-like synoviocytes, either in log phase culture or in quiescent state, was confined within a range. However, when lithium was added to the culture to a final concentration of 100 mM, primary cilia of synoviocytes grew beyond this range, elongating to a length that was on average approximately 3 times the length of untreated cilia. Lithium is a drug approved for treating bipolar disorder. We dissected the molecular targets of this drug, and observed that inhibition of adenylate cyclase III (ACIII) by specific inhibitors mimicked the effects of lithium on primary cilium elongation. Inhibition of GSK-3β by four different inhibitors did not induce primary cilia elongation. ACIII was found in primary cilia of a variety of cell types, and lithium treatment of these cell types led to their cilium elongation. Further, we demonstrate that different cell types displayed distinct sensitivities to the lithium treatment. However, in all cases examined primary cilia elongated as a result of lithium treatment. In particular, two neuronal cell types, rat PC-12 adrenal medulla cells and human astrocytes, developed long primary cilia when lithium was used at or close to the therapeutic relevant concentration (1-2 mM). These results suggest that the length of primary cilia is controlled, at least in part, by the ACIII-cAMP signaling pathway.

Adenylate cyclase regulates elongation of mammalian primary cilia

Energy Technology Data Exchange (ETDEWEB)

Ou, Young; Ruan, Yibing; Cheng, Min; Moser, Joanna J. [Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1 (Canada); Rattner, Jerome B. [Department of Cell Biology and Anatomy, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1 (Canada); Hoorn, Frans A. van der, E-mail: fvdhoorn@ucalgary.ca [Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1 (Canada)

2009-10-01

The primary cilium is a non-motile microtubule-based structure that shares many similarities with the structures of flagella and motile cilia. It is well known that the length of flagella is under stringent control, but it is not known whether this is true for primary cilia. In this study, we found that the length of primary cilia in fibroblast-like synoviocytes, either in log phase culture or in quiescent state, was confined within a range. However, when lithium was added to the culture to a final concentration of 100 mM, primary cilia of synoviocytes grew beyond this range, elongating to a length that was on average approximately 3 times the length of untreated cilia. Lithium is a drug approved for treating bipolar disorder. We dissected the molecular targets of this drug, and observed that inhibition of adenylate cyclase III (ACIII) by specific inhibitors mimicked the effects of lithium on primary cilium elongation. Inhibition of GSK-3{beta} by four different inhibitors did not induce primary cilia elongation. ACIII was found in primary cilia of a variety of cell types, and lithium treatment of these cell types led to their cilium elongation. Further, we demonstrate that different cell types displayed distinct sensitivities to the lithium treatment. However, in all cases examined primary cilia elongated as a result of lithium treatment. In particular, two neuronal cell types, rat PC-12 adrenal medulla cells and human astrocytes, developed long primary cilia when lithium was used at or close to the therapeutic relevant concentration (1-2 mM). These results suggest that the length of primary cilia is controlled, at least in part, by the ACIII-cAMP signaling pathway.

Risk factors associated with the community-acquired colonization of extended-spectrum beta-lactamase (ESBL) positive Escherichia Coli. an exploratory case-control study.

Science.gov (United States)

Leistner, Rasmus; Meyer, Elisabeth; Gastmeier, Petra; Pfeifer, Yvonne; Eller, Christoph; Dem, Petra; Schwab, Frank

2013-01-01

The number of extended-spectrum beta-lactamase (ESBL) positive (+) Escherichia coli is increasing worldwide. In contrast with many other multidrug-resistant bacteria, it is suspected that they predominantly spread within the community. The objective of this study was to assess factors associated with community-acquired colonization of ESBL (+) E. coli. We performed a matched case-control study at the Charité University Hospital Berlin between May 2011 and January 2012. Cases were defined as patients colonized with community-acquired ESBL (+) E. coli identified language most commonly spoken at home (mother tongue). An additional rectal swab was obtained together with the questionnaire to verify colonization status. Genotypes of ESBL (+) E. coli strains were determined by PCR and sequencing. Risk factors associated with ESBL (+) E. coli colonization were analyzed by a multivariable conditional logistic regression analysis. We analyzed 85 cases and 170 controls, respectively. In the multivariable analysis, speaking an Asian language most commonly at home (OR = 13.4, CI 95% 3.3-53.8; p<0.001) and frequently eating pork (≥ 3 meals per week) showed to be independently associated with ESBL colonization (OR = 3.5, CI 95% 1.8-6.6; p<0.001). The most common ESBL genotypes were CTX-M-1 with 44% (n = 37), CTX-M-15 with 28% (n = 24) and CTX-M-14 with 13% (n = 11). An Asian mother tongue and frequently consuming certain types of meat like pork can be independently associated with the colonization of ESBL-positive bacteria. We found neither frequent consumption of poultry nor previous use of antibiotics to be associated with ESBL colonization.

Role of Uropathogenic Escherichia coli Virulence Factors in Development of Urinary Tract Infection and Kidney Damage

Science.gov (United States)

Bien, Justyna; Sokolova, Olga; Bozko, Przemyslaw

2012-01-01

Uropathogenic Escherichia coli (UPEC) is a causative agent in the vast majority of urinary tract infections (UTIs), including cystitis and pyelonephritis, and infectious complications, which may result in acute renal failure in healthy individuals as well as in renal transplant patients. UPEC expresses a multitude of virulence factors to break the inertia of the mucosal barrier. In response to the breach by UPEC into the normally sterile urinary tract, host inflammatory responses are triggered leading to cytokine production, neutrophil influx, and the exfoliation of infected bladder epithelial cells. Several signaling pathways activated during UPEC infection, including the pathways known to activate the innate immune response, interact with calcium-dependent signaling pathways. Some UPEC isolates, however, might possess strategies to delay or suppress the activation of components of the innate host response in the urinary tract. Studies published in the recent past provide new information regarding how virulence factors of uropathogenic E. coli are involved in activation of the innate host response. Despite numerous host defense mechanisms, UPEC can persist within the urinary tract and may serve as a reservoir for recurrent infections and serious complications. Presentation of the molecular details of these events is essential for development of successful strategies for prevention of human UTIs and urological complications associated with UTIs. PMID:22506110

Antibiotic Resistance and Virulence Properties in Escherichia coli ...

African Journals Online (AJOL)

This study determined E. coli resistance to commonly used antibiotics together with their virulence properties in Ile-Ife, Nigeria. A total of 137 E. coli isolates from cases of urinary tract infection were tested for their sensitivity to commonly used antibiotics and possession of virulence factors using standard methods.

Definitive evidence for Ufd2-catalyzed elongation of the ubiquitin chain through Lys48 linkage

International Nuclear Information System (INIS)

Saeki, Yasushi; Tayama, Yoko; Toh-e, Akio; Yokosawa, Hideyoshi

2004-01-01

Saccharomyces cerevisiae Ufd2 is a ubiquitin chain elongation factor in the ubiquitin fusion degradation (UFD) pathway and functions in stress tolerance. A recent study has suggested that the mammalian Ufd2 homologue UFD2a catalyzes formation of Lys27- and Lys33-linked polyubiquitin chains rather than the Lys48-linked chain, but the linkage type of the polyubiquitin chain formed by yeast Ufd2 remains unclear. To determine the property of Ufd2, we reconstituted the UFD pathway using purified enzymes from yeast. Direct determination of the ubiquitin chain linkage type in polyubiquitinated UFD substrates by MALDI-TOF mass spectrometry revealed that Ufd2 catalyzes elongation of the ubiquitin chain through Lys48 linkage

Measurement of elongational viscosity of polymer melts using SER Universal Testing Platform

Czech Academy of Sciences Publication Activity Database

Filip, Petr; Švrčinová, Petra

2012-01-01

Roč. 22, č. 1 (2012), s. 14776 ISSN 1430-6395 R&D Projects: GA ČR GA103/08/1307; GA ČR GA103/09/2066 Institutional research plan: CEZ:AV0Z20600510 Keywords : elongational viscosity * SER Universal Testing Platform * polymer melts * LDPE Subject RIV: BK - Fluid Dynamics Impact factor: 1.226, year: 2012 http://www.ar.ethz.ch/TMPPDF/23074299892.48/ApplRheol_22_14776.pdf

Risk factors associated with the community-acquired colonization of extended-spectrum beta-lactamase (ESBL positive Escherichia Coli. an exploratory case-control study.

Directory of Open Access Journals (Sweden)

Rasmus Leistner

Full Text Available BACKGROUND: The number of extended-spectrum beta-lactamase (ESBL positive (+ Escherichia coli is increasing worldwide. In contrast with many other multidrug-resistant bacteria, it is suspected that they predominantly spread within the community. The objective of this study was to assess factors associated with community-acquired colonization of ESBL (+ E. coli. METHODS: We performed a matched case-control study at the Charité University Hospital Berlin between May 2011 and January 2012. Cases were defined as patients colonized with community-acquired ESBL (+ E. coli identified <72 h after hospital admission. Controls were patients that carried no ESBL-positive bacteria but an ESBL-negative E.coli identified <72 h after hospital admission. Two controls per case were chosen from potential controls according to admission date. Case and control patients completed a questionnaire assessing nutritional habits, travel habits, household situation and language most commonly spoken at home (mother tongue. An additional rectal swab was obtained together with the questionnaire to verify colonization status. Genotypes of ESBL (+ E. coli strains were determined by PCR and sequencing. Risk factors associated with ESBL (+ E. coli colonization were analyzed by a multivariable conditional logistic regression analysis. RESULTS: We analyzed 85 cases and 170 controls, respectively. In the multivariable analysis, speaking an Asian language most commonly at home (OR = 13.4, CI 95% 3.3-53.8; p<0.001 and frequently eating pork (≥ 3 meals per week showed to be independently associated with ESBL colonization (OR = 3.5, CI 95% 1.8-6.6; p<0.001. The most common ESBL genotypes were CTX-M-1 with 44% (n = 37, CTX-M-15 with 28% (n = 24 and CTX-M-14 with 13% (n = 11. CONCLUSION: An Asian mother tongue and frequently consuming certain types of meat like pork can be independently associated with the colonization of ESBL-positive bacteria. We found neither frequent consumption

Dialogue between E. coli free radical pathways and the mitochondria of C. elegans.

Science.gov (United States)

Govindan, J Amaranath; Jayamani, Elamparithi; Zhang, Xinrui; Mylonakis, Eleftherios; Ruvkun, Gary

2015-10-06

The microbial world presents a complex palette of opportunities and dangers to animals, which have developed surveillance and response strategies to hints of microbial intent. We show here that the mitochondrial homeostatic response pathway of the nematode Caenorhabditis elegans responds to Escherichia coli mutations that activate free radical detoxification pathways. Activation of C. elegans mitochondrial responses could be suppressed by additional mutations in E. coli, suggesting that C. elegans responds to products of E. coli to anticipate challenges to its mitochondrion. Out of 50 C. elegans gene inactivations known to mediate mitochondrial defense, we found that 7 genes were required for C. elegans response to a free radical producing E. coli mutant, including the bZip transcription factor atfs-1 (activating transcription factor associated with stress). An atfs-1 loss-of-function mutant was partially resistant to the effects of free radical-producing E. coli mutant, but a constitutively active atfs-1 mutant growing on wild-type E. coli inappropriately activated the pattern of mitochondrial responses normally induced by an E. coli free radical pathway mutant. Carbonylated proteins from free radical-producing E. coli mutant may directly activate the ATFS-1/bZIP transcription factor to induce mitochondrial stress response: feeding C. elegans with H2O2-treated E. coli induces the mitochondrial unfolded protein response, and inhibition of a gut peptide transporter partially suppressed C. elegans response to free radical damaged E. coli.

Ribosome-dependent ATPase interacts with conserved membrane protein in Escherichia coli to modulate protein synthesis and oxidative phosphorylation.

Directory of Open Access Journals (Sweden)

Mohan Babu

Full Text Available Elongation factor RbbA is required for ATP-dependent deacyl-tRNA release presumably after each peptide bond formation; however, there is no information about the cellular role. Proteomic analysis in Escherichia coli revealed that RbbA reciprocally co-purified with a conserved inner membrane protein of unknown function, YhjD. Both proteins are also physically associated with the 30S ribosome and with members of the lipopolysaccharide transport machinery. Genome-wide genetic screens of rbbA and yhjD deletion mutants revealed aggravating genetic interactions with mutants deficient in the electron transport chain. Cells lacking both rbbA and yhjD exhibited reduced cell division, respiration and global protein synthesis as well as increased sensitivity to antibiotics targeting the ETC and the accuracy of protein synthesis. Our results suggest that RbbA appears to function together with YhjD as part of a regulatory network that impacts bacterial oxidative phosphorylation and translation efficiency.

Endogenous ADP-ribosylation of elongation factor 2 in polyoma virus-transformed baby hamster kidney cells

International Nuclear Information System (INIS)

Fendrick, J.L.; Iglewski, W.J.

1989-01-01

Polyoma virus-transformed baby hamster kidney (pyBHK) cells were cultured in medium containing [ 32 P]orthophosphate and 105 (vol/vol) fetal bovine serum. A 32 P-labeled protein with an apparent molecular mass of 97 kDa was immunoprecipitated from cell lysates with antiserum to ADP-ribosylated elongation factor 2 (EF-2). The 32 P labeling of the protein was enhanced by culturing cells in medium containing 2% serum instead of 10% serum. The 32 P label was completely removed from the protein by treatment with snake venom phosphodiesterase and the digestion product was identified as [ 32 P]AMP, indicating the protein was mono-ADP-ribosylated. HPLC analysis of tryptic peptides of the 32 P-labeled 97-kDa protein and purified EF-2, which was ADP-ribosylated in vitro with diphtheria toxin fragment A and [ 32 P]NAD, demonstrated an identical labeled peptide in the two proteins. The data strongly suggest that EF-2 was endogenously ADP-ribosylated in pyBHK cells. Maximum incorporation of radioactivity in EF-2 occurred by 12 hr and remained constant over the subsequent 12 hr. It was estimated that 30-35% of the EF-2 was ADP-ribosylated in cells cultured in medium containing 2% serum. When 32 P-labeled cultures were incubated in medium containing unlabeled phosphate, the 32 P label was lost from the EF-2 within 30 min

Uni-axial Elongational Viscosity of Linear and Branched polymer melts

DEFF Research Database (Denmark)

Hassager, Ole; Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz

2005-01-01

About 40 years ago interest in the measurement of elongational viscosity of polymer melts started to grow. Here we present measurements of transient (and steady) uni-axial elongational viscosity, using the FSR, of the following melts: Four narrow MMD polystyrene (PS) samples with weight......-average molar mass Mw in the range of 50k to 390k. Three different bi-disperse samples, mixed from the narrow MMD PS. Two low-density polyethylene (LDPE) melts (Lupolen 1840D and 3020D). A steady-state viscosity was kept for 1-2.5 Hencky strain units in all measurements.The measurements on the bi-disperse PS...... melts have demonstrated that both the transient and steady elongational viscosity is quite sensitive to polydispersity. Bi-disperse PS resembles the behaviour of mono-disperse melts only at elongational rates larger then the inverse of maximal time constant of the smallest molecule. As observed in Boger...

Fruiting branch K+ level affects cotton fibre elongation through osmoregulation

Directory of Open Access Journals (Sweden)

Jiashuo eYang

2016-01-01

Full Text Available Potassium (K deficiency in cotton plants results in reduced fibre length. As one of the primary osmotica, K+ contributes to an increase in cell turgor pressure during fibre elongation. Therefore, it is hypothesized that fibre length is affected by K deficiency through an osmotic pathway, so in 2012 and 2013, an experiment was conducted to test this hypothesis by imposing three potassium supply regimes (0, 125, 250 kg K ha-1 on a low-K-sensitive cultivar, Siza 3, and a low-K-tolerant cultivar, Simian 3. We found that fibres were longer in the later season bolls than in the earlier ones in cotton plants grown under normal growth conditions, but later season bolls showed a greater sensitivity to low-K stress, especially the low-K sensitive genotype. We also found that the maximum velocity of fibre elongation (Vmax is the parameter that best reflects the change in fibre elongation under K deficiency. This parameter mostly depends on cell turgor, so the content of the osmotically active solutes was analysed accordingly. Statistical analysis showed that K+ was the major osmotic factor affecting fibre length, and malate was likely facilitating K+ accumulation into fibres, which enabled the low-K-tolerant genotype to cope with low-K stress. Moreover, the low-K-tolerant genotype tended to have greater K+ absorptive capacities in the upper fruiting branches. Based on our findings, we suggest a fertilization scheme for Gossypium hirsutum that adds extra potash fertilizer or distributes it during the development of late season bolls to mitigate K deficiency in the second half of the growth season and to enhance fibre length in late season bolls.

Carbon nanoparticles as detection labels in antibody microarrays. Detection of genes encoding virulence factors in Shiga toxin-producing Escherichia coli.

NARCIS (Netherlands)

Noguera, P.S.; Posthuma-Trumpie, G.A.; Tuil, Van M.; Wal, van der F.J.; Boer, De A.; Moers, A.P.H.A.; Amerongen, Van A.

2011-01-01

The present study demonstrates that carbon nanoparticles (CNPs) can be used as labels in microarrays. CNPs were used in nucleic acid microarray immunoassays (NAMIAs) for the detection of different Shiga toxin-producing Escherichia coli (STEC) virulence factors: four genes specific for STEC (vt1,

Light quality and elongation growth. 1: Effect of duration and time of far red irradiation on stem elongation of Argyranthemum frutescens cv. Silver Leaf

International Nuclear Information System (INIS)

Jatzkowski, M.; Zimmer, K.

1994-01-01

The phenomenon of stem elongation by far red irradiation was shown with Argyranthemum frutescens 'Silver Leaf'. Stem elongation was promoted by incandescent lighting (mainly far red) during the day and night period. More intense reactions were observed with the isolated application during the nighttime. Reaction was strongly modified by the point of time the application took place. No effect could be shown by lighting with incandescent lamps for two hours during the daytime given within the first six hours of the main light period. During the nighttime two hours of lighting (incandescent lamps) promoted stem elongation atany point of time, especially in the middle of the dark period

Scattering phaseshift formulas for mesons and baryons in elongated boxes

Science.gov (United States)

Lee, Frank X.; Alexandru, Andrei

2018-03-01

We derive Lüscher phaseshift formulas for two-particle states in boxes elongated in one of the dimensions. Such boxes offer a cost-effective way of varying the relative momentum of the particles. Boosted states in the elongated direction, which allow wider access to energies, are also considered. The formulas for the various scenarios (moving and zero-momentum states in cubic and elongated boxes) are compared and relations between them are clarified. The results are applicable to a wide set of meson-meson and meson-baryon elastic scattering processes, with the two-particle system having equal or unequal masses.

mRNA secondary structure at start AUG codon is a key limiting factor for human protein expression in Escherichia coli

International Nuclear Information System (INIS)

Zhang Weici; Xiao Weihua; Wei Haiming; Zhang Jian; Tian Zhigang

2006-01-01

Codon usage and thermodynamic optimization of the 5'-end of mRNA have been applied to improve the efficiency of human protein production in Escherichia coli. However, high level expression of human protein in E. coli is still a challenge that virtually depends upon each individual target genes. Using human interleukin 10 (huIL-10) and interferon α (huIFN-α) coding sequences, we systematically analyzed the influence of several major factors on expression of human protein in E. coli. The results from huIL-10 and reinforced by huIFN-α showed that exposing AUG initiator codon from base-paired structure within mRNA itself significantly improved the translation of target protein, which resulted in a 10-fold higher protein expression than the wild-type genes. It was also noted that translation process was not affected by the retained short-range stem-loop structure at Shine-Dalgarno (SD) sequences. On the other hand, codon-optimized constructs of huIL-10 showed unimproved levels of protein expression, on the contrary, led to a remarkable RNA degradation. Our study demonstrates that exposure of AUG initiator codon from long-range intra-strand secondary structure at 5'-end of mRNA may be used as a general strategy for human protein production in E. coli

Discontinuation of orthokeratology on eyeball elongation (DOEE).

Science.gov (United States)

Cho, P; Cheung, S W

2017-04-01

To evaluate and compare changes in axial elongation, over a 14-month period, in subjects who discontinued and then resumed ortho-k lens wear with those who continued to wear their lenses or spectacles following a 2-year myopia control study. This single masked, prospective study recruited subjects who had just completed a 2-year myopia control study. Ortho-k subjects were classified as Group OKc, in which subjects continued ortho-k lens wear for the duration of the study; or Group OKd in which subjects discontinued lens wear for seven months and wore single-vision spectacles (Phase I) and then resumed ortho-k lens wear for another seven months (Phase II). Spectacle-wearing control subjects from the initial myopia control study continued wearing spectacles as control subjects. Axial lengths were measured at scheduled visits using the IOLMaster. Thirteen, 16, and 15 Control, OKc, and OKd subjects, aged 8-14 years, respectively completed the study. Significant increase in axial elongation was found in OKd subjects only in Phase I but not in Phase II. On resuming lens wear, in Phase II, the rate of axial elongation was no longer significantly different from those of the Control or OKc subjects. Stopping ortho-k lens wear at or before the age of 14 years led to a more rapid increase in axial length; comparable to those wearing spectacles during the initial 2-year myopia control study, but greater than the Control and OKc group in this study. Axial elongation slowed again with resumed lens wear after six months. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Viscosity overshoot in the start-up of uniaxial elongation of low density polyethylene melts

DEFF Research Database (Denmark)

Rasmussen, Henrik K.; Nielsen, Jens Kromann; Bach, Anders

2005-01-01

The transient uniaxial elongational viscosity of BASF Lupolen 1840D and 3020D melts has been measured on a filament stretch rheometer up to Hencky strains of 6-7. The elongational viscosity of both melts was measured at 130 degrees C within a broad range of elongational rates. At high elongation ...

Global transcriptional regulatory network for Escherichia coli robustly connects gene expression to transcription factor activities

Science.gov (United States)

Fang, Xin; Sastry, Anand; Mih, Nathan; Kim, Donghyuk; Tan, Justin; Lloyd, Colton J.; Gao, Ye; Yang, Laurence; Palsson, Bernhard O.

2017-01-01

Transcriptional regulatory networks (TRNs) have been studied intensely for >25 y. Yet, even for the Escherichia coli TRN—probably the best characterized TRN—several questions remain. Here, we address three questions: (i) How complete is our knowledge of the E. coli TRN; (ii) how well can we predict gene expression using this TRN; and (iii) how robust is our understanding of the TRN? First, we reconstructed a high-confidence TRN (hiTRN) consisting of 147 transcription factors (TFs) regulating 1,538 transcription units (TUs) encoding 1,764 genes. The 3,797 high-confidence regulatory interactions were collected from published, validated chromatin immunoprecipitation (ChIP) data and RegulonDB. For 21 different TF knockouts, up to 63% of the differentially expressed genes in the hiTRN were traced to the knocked-out TF through regulatory cascades. Second, we trained supervised machine learning algorithms to predict the expression of 1,364 TUs given TF activities using 441 samples. The algorithms accurately predicted condition-specific expression for 86% (1,174 of 1,364) of the TUs, while 193 TUs (14%) were predicted better than random TRNs. Third, we identified 10 regulatory modules whose definitions were robust against changes to the TRN or expression compendium. Using surrogate variable analysis, we also identified three unmodeled factors that systematically influenced gene expression. Our computational workflow comprehensively characterizes the predictive capabilities and systems-level functions of an organism’s TRN from disparate data types. PMID:28874552

Elongation Factor-1α Accurately Reconstructs Relationships Amongst Psyllid Families (Hemiptera: Psylloidea), with Possible Diagnostic Implications.

Science.gov (United States)

Martoni, Francesco; Bulman, Simon R; Pitman, Andrew; Armstrong, Karen F

2017-12-05

The superfamily Psylloidea (Hemiptera: Sternorrhyncha) lacks a robust multigene phylogeny. This impedes our understanding of the evolution of this group of insects and, consequently, an accurate identification of individuals, of their plant host associations, and their roles as vectors of economically important plant pathogens. The conserved nuclear gene elongation factor-1 alpha (EF-1α) has been valuable as a higher-level phylogenetic marker in insects and it has also been widely used to investigate the evolution of intron/exon structure. To explore evolutionary relationships among Psylloidea, polymerase chain reaction amplification and nucleotide sequencing of a 250-bp EF-1α gene fragment was applied to psyllids belonging to five different families. Introns were detected in three individuals belonging to two families. The nine genera belonging to the family Aphalaridae all lacked introns, highlighting the possibility of using intron presence/absence as a diagnostic tool at a family level. When paired with cytochrome oxidase I gene sequences, the 250 bp EF-1α sequence appeared to be a very promising higher-level phylogenetic marker for psyllids. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Prevalencia y factores de riesgo para infecciones del tracto urinario de inicio en la comunidad causadas por Escherichia coli productor de betalactamasas de espectro extendido en Colombia

Science.gov (United States)

Blanco, Victor M.; Maya, Juan J.; Correa, Adriana; Perenguez, Marcela; Muñoz, Juan S.; Motoa, Gabriel; Pallares, Christian J.; Rosso, Fernando; Matta, Lorena; Celis, Yamile; Garzon, Martha; Villegas, y María V.

2016-01-01

RESUMEN Introducción Las infecciones del tracto urinario (ITU) son frecuentes en la comunidad. Sin embargo, la información de aislamientos resistentes en este contexto es limitada en Latinoamérica. Este estudio tiene como objetivo determinar la prevalencia y los factores de riesgo asociados con ITU de inicio en la comunidad (ITU-IC) causadas por Escherichia coli productor de betalactamasas de espectro extendido (BLEE) en Colombia. Materiales y métodos Entre agosto y diciembre de 2011 se realizó un estudio de casos y controles en 3 instituciones de salud de tercer nivel en Colombia. Se invitó a participar a todos los pacientes admitidos a urgencias con diagnóstico probable de ITU-IC, y se les pidió una muestra de orina. En los aislamien-tos de E. coli se realizaron pruebas confirmatorias para BLEE, susceptibilidad antibiótica, caracterización molecular (PCR en tiempo real para genes bla, repetitive element palindromic PCR [rep-PCR], multilocus sequence typing [MLST] y factores de virulencia por PCR). Se obtuvo información clínica y epidemiológica, y posteriormente se realizó el análisis estadístico. Resultados De los 2.124 pacientes seleccionados, 629 tuvieron un urocultivo positivo, en 431 de estos se aisló E. coli, 54 fueron positivos para BLEE y 29 correspondieron a CTX-M-15. La mayoría de los aislamientos de E. coli productor de BLEE fueron sensibles a ertapenem, fosfomicina y amikacina. La ITU complicada se asoció fuertemente con infecciones por E. coli productor de BLEE (OR = 3,89; IC 95%: 1,10–13,89; p = 0,03). E. coli productor de CTX-M-15 mostró 10 electroferotipos diferentes; de estos, el 65% correspondieron al ST131. La mayoría de estos aislamientos tuvieron 8 de los 9 factores de virulencia analizados. Discusión E. coli portador del gen blaCTX-M-15 asociado al ST131 sigue siendo frecuente en Colombia. La presencia de ITU-IC complicada aumenta el riesgo de tener E. coli productor de BLEE, lo cual debe tenerse en cuenta para ofrecer

Photo-oxidation of LDPE: Effects on elongational viscosity

Science.gov (United States)

Rolón-Garrido, Víctor H.; Wagner, Manfred H.

2013-04-01

Sheets of low-density polyethylene (LDPE) were photo-oxidatively treated at room temperature, and subsequently characterized rheologically in the melt state by shear and uniaxial extensional experiments. For photo-oxidation, a xenon lamp was used to irradiate the samples for times between 1 day and 6 weeks. Linear-viscoelastic characterization was performed in a temperature range of 130 to 220°C to obtain the master curve at 170°C, the reference temperature at which the elongational viscosities were measured. Linear viscoelasticity is increasingly affected by increasing photo-oxidation due to crosslinking of LDPE, as corroborated by an increasing gel fraction as determined by a solvent extraction method. The elongational measurements reveal a strong enhancement of strain hardening until a saturation level is achieved. The elongational data are analyzed in the frame work of two constitutive equations, the rubber-like liquid and the molecular stress function models. Within the experimental window, time-deformation separability is confirmed for all samples, independent of the degree of photo-oxidation.

Production of feline leukemia inhibitory factor with biological activity in Escherichia coli.

Science.gov (United States)

Kanegi, R; Hatoya, S; Tsujimoto, Y; Takenaka, S; Nishimura, T; Wijewardana, V; Sugiura, K; Takahashi, M; Kawate, N; Tamada, H; Inaba, T

2016-07-15

Leukemia inhibitory factor (LIF) is a cytokine which is essential for oocyte and embryo development, embryonic stem cell, and induced pluripotent stem cell maintenance. Leukemia inhibitory factor improves the maturation of oocytes in the human and the mouse. However, feline LIF (fLIF) cloning and effects on oocytes during IVM have not been reported. Thus, we cloned complete cDNA of fLIF and examined its biological activity and effects on oocytes during IVM in the domestic cat. The aminoacid sequence of fLIF revealed a homology of 81% or 92% with that of mouse or human. The fLIF produced by pCold TF DNA in Escherichia coli was readily soluble and after purification showed bioactivity in maintaining the undifferentiated state of mouse embryonic stem cells and enhancing the proliferation of human erythrocyte leukemia cells. Furthermore, 10- and 100-ng/mL fLIF induced cumulus expansion with or without FSH and EGF (P Feline LIF will further improve reproduction and stem cell research in the feline family. Copyright © 2016 Elsevier Inc. All rights reserved.

Bilateral elongated styloid process: Its anatomical, embryological and clinical implications

Directory of Open Access Journals (Sweden)

Bagoji Ishwar B, Hadimani Gavishiddappa A, Patil Balasaheb G, Bannur Balappa M,Ambadasu B

2013-04-01

Full Text Available The styloid process is a slender, elongated, cylindrical bony projection from temporal bone. It normally varies in length from 2 cm to 3 cm. During a routine demonstration of skull for MBBS students we found the bilateral elongated styloid process in dry human skull. The length of elongation measured on the right and left side was 6.0 & 5.9 cms respectively. Such abnormal elongation of the styloid process may cause compression on a number of vital vessels and nerves related to it, producing inflammatory changes that include continuous chronic pain in the pharyngeal region. Mechanical stresses stretching the second brachial arch during fetal development probably induce variable involvement of Reichert’s cartilage in morphogenesis of the styloid process. It is important that clinicians especially dentists and otolaryngologists are aware of the natural variations of the styloid process and do not consider the styloid process with a length of 30 mm as an abnormality or as an anomaly.

Contribution of Arg288 of Escherichia coli elongation factor Tu to translational functionality

DEFF Research Database (Denmark)

Rattenborg, Thomas; Nautrup-Pedersen, Gitte; Clark, Brian F. C.

1997-01-01

. This network is disrupted upon formation of the ternary complex. Arg288 was replaced by alanine, isoleucine, lysine or glutamic acid, and the resulting mutants have been subjected to an in vitro characterisation with the aim of clarifying the function of Arg288. Unexpectedly, the mutants behaved like the wild...

An Equatorial Contractile Mechanism Drives Cell Elongation but not Cell Division

Science.gov (United States)

Denker, Elsa; Bhattachan, Punit; Deng, Wei; Mathiesen, Birthe T.; Jiang, Di

2014-01-01

Cell shape changes and proliferation are two fundamental strategies for morphogenesis in animal development. During embryogenesis of the simple chordate Ciona intestinalis, elongation of individual notochord cells constitutes a crucial stage of notochord growth, which contributes to the establishment of the larval body plan. The mechanism of cell elongation is elusive. Here we show that although notochord cells do not divide, they use a cytokinesis-like actomyosin mechanism to drive cell elongation. The actomyosin network forming at the equator of each notochord cell includes phosphorylated myosin regulatory light chain, α-actinin, cofilin, tropomyosin, and talin. We demonstrate that cofilin and α-actinin are two crucial components for cell elongation. Cortical flow contributes to the assembly of the actomyosin ring. Similar to cytokinetic cells, membrane blebs that cause local contractions form at the basal cortex next to the equator and participate in force generation. We present a model in which the cooperation of equatorial actomyosin ring-based constriction and bleb-associated contractions at the basal cortex promotes cell elongation. Our results demonstrate that a cytokinesis-like contractile mechanism is co-opted in a completely different developmental scenario to achieve cell shape change instead of cell division. We discuss the occurrences of actomyosin rings aside from cell division, suggesting that circumferential contraction is an evolutionally conserved mechanism to drive cell or tissue elongation. PMID:24503569

A Premature Termination of Human Epidermal Growth Factor Receptor Transcription in Escherichia coli

Directory of Open Access Journals (Sweden)

Jihene Elloumi-Mseddi

2014-01-01

Full Text Available Our success in producing an active epidermal growth factor receptor (EGFR tyrosine kinase in Escherichia coli encouraged us to express the full-length receptor in the same host. Despite its large size, we were successful at producing the full-length EGFR protein fused to glutathione S-transferase (GST that was detected by Western blot analysis. Moreover, we obtained a majoritarian truncated GST-EGFR form detectable by gel electrophoresis and Western blot. This truncated protein was purified and confirmed by MALDI-TOF/TOF analysis to belong to the N-terminal extracellular region of the EGFR fused to GST. Northern blot analysis showed two transcripts suggesting the occurrence of a transcriptional arrest.

Identification of Genes Important for Growth of Asymptomatic Bacteriuria Escherichia coli in Urine

DEFF Research Database (Denmark)

Vejborg, Rebecca Munk; de Evgrafov, Mari Cristina Rodriguez; Phan, Minh Duy

2012-01-01

Escherichia coli is the most important etiological agent of urinary tract infections (UTIs). Unlike uropathogenic E. coli, which causes symptomatic infections, asymptomatic bacteriuria (ABU) E. coli strains typically lack essential virulence factors and colonize the bladder in the absence...

The Effects of Microgravity on Seated Height (Spinal Elongation)

Science.gov (United States)

Young, K. S.; Rajulu, S.

2011-01-01

ABSTRACT Many physiological factors, such as spinal elongation, fluid shifts, bone atrophy, and muscle loss, occur during an exposure to a microgravity environment. Spinal elongation is just one of the factors that can also affect the safety and performance of a crewmember while in space. Spinal elongation occurs due to the lack of gravity/compression on the spinal column. This allows for the straightening of the natural spinal curve. There is a possible fluid shift in the inter-vertebral disks that may also result in changes in height. This study aims at collecting the overall change in seated height for crewmembers exposed to a microgravity environment. During previous Programs, Apollo-Soyuz Test Project (ASTP) and Skylab, spinal elongation data was collected from a small number of subjects in a standing posture but were limited in scope. Data from these studies indicated a quick increase in stature during the first few days of weightlessness, after which stature growth reached a plateau resulting in up to a 3% increase of the original measurement [1-5]. However, this data was collected only for crewmembers in standing posture and not in a seated posture. Seated height may have a different effect than standing height due to a change in posture as well as due to a compounded effect of wearing restraints and a potential compression of the gluteal area. Seated height was deemed as a critical measurement in the design of the Constellation Program s (CxP) Crew Exploration Vehicle (CEV), called Orion which is now the point-of-departure vehicle for the Multi-Purpose Crew Vehicle (MPCV) Program; therefore a better understanding of the effects of microgravity on seated height is necessary. Potential changes in seated height that may not have impacted crew accommodation in previous Programs will have significant effects on crew accommodation due to the layout of seats in the Orion.. The current and existing configuration is such that the four crewmembers are stacked two by

Characterization of clinically isolated thymidine-dependent small-colony variants of Escherichia coli producing extended-spectrum β-lactamase.

Science.gov (United States)

Negishi, Tatsuya; Matsumoto, Takehisa; Horiuchi, Kazuki; Kasuga, Eriko; Natori, Tatsuya; Matsuoka, Mina; Ogiwara, Naoko; Sugano, Mitsutoshi; Uehara, Takeshi; Nagano, Noriyuki; Honda, Takayuki

2018-01-01

Thymidine-dependent small-colony variants (TD-SCVs) are difficult to detect or test for antimicrobial susceptibility. We investigated the characteristics of clonal TD-SCVs of Escherichia coli, both with and without blaCTX-M-3, isolated from a patient. Mutation in the thyA gene was analysed by sequencing, and morphological abnormalities in the colonies and cells of the isolates were examined. Additionally, conjugational transfer experiments were performed to prove the horizontal transferability of plasmids harbouring resistance genes. The TD-SCVs contained a single nucleotide substitution in the thyA gene, c.62G>A, corresponding to p.Arg21His. Morphologically, their colonies were more translucent and flattened than those of the wild-type strain. In addition, cells of the TD-SCVs were swollen and elongated, sometimes with abnormal and incomplete divisions; a large amount of cell debris was also observed. Changing c.62G>A back to the wild-type sequence reversed these abnormalities. Conjugational transfer experiments showed that the TD-SCV of E. coli with blaCTX-M-3 failed to transfer blaCTX-M-3 to E. coli CSH2. However, the TD-SCV of E. coli without blaCTX-M-3 experimentally received the plasmid encoding blaSHV-18 from Klebsiella pneumoniae ATCC 700603 and transferred it to E. coli CSH2. Mutation in the thyA gene causes morphological abnormalities in the colonies and cells of E. coli, as well as inducing thymidine auxotrophy. In addition, TD-SCVs horizontally transmit plasmids encoding resistance genes. It is important to detect TD-SCVs based on their characteristics because they serve as reservoirs of transferable antibiotic resistance plasmids.

Chlamydia abortus YhbZ, a truncated Obg family GTPase, associates with the Escherichia coli large ribosomal subunit.

Science.gov (United States)

Polkinghorne, Adam; Vaughan, Lloyd

2011-01-01

The stringent stress response is vital for bacterial survival under adverse environmental conditions. Obligate intracellular Chlamydia lack key stringent response proteins, but nevertheless can interrupt the cell cycle and enter stasis or persistence upon amino acid starvation. A possible key protein retained is YhbZ, a homologue of the ObgE guanosine triphosphatase (GTPase) superfamily connecting the stringent stress response to ribosome maturation. Curiously, chlamydial YhbZ lacks the ObgE C-terminal domain thought to be essential for binding the large ribosomal subunit. We expressed recombinant Chlamydia abortus YhbZ and showed it to be a functional GTPase, with similar activity to other Obg GTPase family members. As Chlamydia are resistant to genetic manipulation, we performed heterologous expression and gradient centrifugation experiments in Escherichia coli and found that, despite the missing C-terminal domain, C. abortus YhbZ co-fractionates with the E. coli 50S large ribosomal subunit. In addition, overexpression of chlamydial YhbZ in E. coli leads to growth defects and elongation, as reported for other Obg members. YhbZ did not complement an E. coli obgE temperature-sensitive mutant, indicating the C-terminal acidic domain may have an additional role. This data supports a role for YhbZ linking the chlamydial stress response to ribosome function and cellular growth. Copyright © 2010 Elsevier Ltd. All rights reserved.

Jasmonate inhibits COP1 activity to suppress hypocotyl elongation and promote cotyledon opening in etiolated Arabidopsis seedlings.

Science.gov (United States)

Zheng, Yuyu; Cui, Xuefei; Su, Liang; Fang, Shuang; Chu, Jinfang; Gong, Qingqiu; Yang, Jianping; Zhu, Ziqiang

2017-06-01

A germinating seedling undergoes skotomorphogenesis to emerge from the soil and reach for light. During this phase, the cotyledons are closed, and the hypocotyl elongates. Upon exposure to light, the seedling rapidly switches to photomorphogenesis by opening its cotyledons and suppressing hypocotyl elongation. The E3 ubiquitin ligase CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) is critical for maintaining skotomorphogenesis. Here, we report that jasmonate (JA) suppresses hypocotyl elongation and stimulates cotyledon opening in etiolated seedlings, partially phenocopying cop1 mutants in the dark. We also find that JA stabilizes several COP1-targeted transcription factors in a COP1-dependent manner. RNA-seq analysis further defines a JA-light co-modulated and cop1-dependent transcriptome, which is enriched for auxin-responsive genes and genes participating in cell wall modification. JA suppresses COP1 activity through at least two distinct mechanisms: decreasing COP1 protein accumulation in the nucleus; and reducing the physical interaction between COP1 and its activator, SUPPRESSOR OF PHYTOCHROME A-105 1 (SPA1). Our work reveals that JA suppresses COP1 activity to stabilize COP1 targets, thereby inhibiting hypocotyl elongation and stimulating cotyledon unfolding in etiolated Arabidopsis seedlings. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

Tendon Contraction After Cyclic Elongation Is an Age-Dependent Phenomenon: In Vitro and In Vivo Comparisons.

Science.gov (United States)

Lavagnino, Michael; Bedi, Asheesh; Walsh, Christopher P; Sibilsky Enselman, Elizabeth R; Sheibani-Rad, Shahin; Arnoczky, Steven P

2014-06-01

Tendons are viscoelastic tissues that deform (elongate) in response to cyclic loading. However, the ability of a tendon to recover this elongation is unknown. Tendon length significantly increases after in vivo or in vitro cyclic loading, and the ability to return to its original length through a cell-mediated contraction mechanism is an age-dependent phenomenon. Controlled laboratory study. In vitro, rat tail tendon fascicles (RTTfs) from Sprague-Dawley rats of 3 age groups (1, 3, and 12 months) underwent 2% cyclic strain at 0.17 Hz for 2 hours, and the percentages of elongation were determined. After loading, the RTTfs were suspended for 3 days under tissue culture conditions and photographed daily to determine the amount of length contraction. In vivo, healthy male participants (n = 29; age, 19-49 years) had lateral, single-legged weightbearing radiographs taken of the knee at 60° of flexion immediately before, immediately after, and 24 hours after completing eccentric quadriceps loading exercises on the dominant leg to fatigue. Measurements of patellar tendon length were taken from the radiographs, and the percentages of tendon elongation and subsequent contraction were calculated. In vitro, cyclic loading increased the length of all RTTfs, with specimens from younger (1 and 3 months) rats demonstrating significantly greater elongation than those from older (12 months) rats (P = .009). The RTTfs contracted to their original length significantly faster (P fashion, with younger animals contracting faster. In vivo, repetitive eccentric loading exercises significantly increased patellar tendon length (P 30 years). Cyclic tendon loading results in a significant increase in tendon elongation under both in vitro and in vivo conditions. Tendons in both conditions demonstrated an incomplete return to their original length after 24 hours, and the extent of this return was age dependent. The age- and time-dependent contraction of tendons, elongated after repetitive

Adherens junction distribution mechanisms during cell-cell contact elongation in Drosophila.

Directory of Open Access Journals (Sweden)

Gabrielle Goldenberg

Full Text Available During Drosophila gastrulation, amnioserosa (AS cells flatten and spread as an epithelial sheet. We used AS morphogenesis as a model to investigate how adherens junctions (AJs distribute along elongating cell-cell contacts in vivo. As the contacts elongated, total AJ protein levels increased along their length. However, genetically blocking this AJ addition indicated that it was not essential for maintaining AJ continuity. Implicating other remodeling mechanisms, AJ photobleaching revealed non-directional lateral mobility of AJs along the elongating contacts, as well as local AJ removal from the membranes. Actin stabilization with jasplakinolide reduced AJ redistribution, and live imaging of myosin II along elongating contacts revealed fragmented, expanding and contracting actomyosin networks, suggesting a mechanism for lateral AJ mobility. Actin stabilization also increased total AJ levels, suggesting an inhibition of AJ removal. Implicating AJ removal by endocytosis, clathrin endocytic machinery accumulated at AJs. However, dynamin disruption had no apparent effect on AJs, suggesting the involvement of redundant or dynamin-independent mechanisms. Overall, we propose that new synthesis, lateral diffusion, and endocytosis play overlapping roles to populate elongating cell-cell contacts with evenly distributed AJs in this in vivo system.

Methanol as an alternative electron donor in chain elongation for butyrate and caproate formation

OpenAIRE

Chen, W.S.; Ye, Y.; Steinbusch, K.J.J.; Strik, D.P.B.T.B.; Buisman, C.J.N.

2016-01-01

Chain elongation is an emerging mixed culture biotechnology converting acetate into valuable biochemicals by using ethanol as an external electron donor. In this study we proposed to test another potential electron donor, methanol, in chain elongation. Methanol can be produced through the thermochemical conversion of lignocellulosic biowaste. Use of methanol in chain elongation integrates the lignocellulosic feedstocks and the thermochemical platform technologies into chain elongation. After ...

Status of the tube elongation problem as of June 1976

International Nuclear Information System (INIS)

Alexander, W.K.

1976-01-01

It was discovered in May of 1971 that the N Reactor process tubes had apparently increased in length by as much as one inch. Preliminary observations and measurements led to the tentative conclusion that this observed elongation was linear with accumulated tube exposure and also that it was related in some manner to the tube fabrication process. It appeared that the observed elongation was approximately proportional to the degree of cold work retained in the finished tubes. This latter conclusion was based on the observation that those tubes with approximately 17-18 percent cold work had elongated only about half as much as the standard 30-percent-cold-worked tubes. It was immediately recognized that if such elongation was to continue unchecked it could pose a limit to reactor life since total possible tube expansion, from all causes, is limited to 1.75 inches by nozzle design considerations as shown in Figure 1. Thermal and hydraulic expansion were calculated to total approximately 0.75 inches which left only one inch available to accommodate tube growth or creep. Since discovery of this phenomenon, an extensive measurements program has been carried out to evaluate the extent and rate of tube elongation. Two corrective approaches have been developed and a small number of tubes were modified by each method during the 1976 summer outage. During the 1974, 1975 and 1976 Summer Outages, measurements were made on all tubes to determine the clearance remaining between the nozzle keys and the gas packing ring. These readings not only give an overall picture of the extent of elongation, but also provide immediate data indicating which tubes are about out of clearance. The report presents an evaluation of the measurements taken to date

Endogenous ADP-ribosylation of elongation factor 2 in polyoma virus-transformed baby hamster kidney cells

Energy Technology Data Exchange (ETDEWEB)

Fendrick, J.L.; Iglewski, W.J. (Univ. of Rochester, NY (USA))

1989-01-01

Polyoma virus-transformed baby hamster kidney (pyBHK) cells were cultured in medium containing ({sup 32}P)orthophosphate and 105 (vol/vol) fetal bovine serum. A {sup 32}P-labeled protein with an apparent molecular mass of 97 kDa was immunoprecipitated from cell lysates with antiserum to ADP-ribosylated elongation factor 2 (EF-2). The {sup 32}P labeling of the protein was enhanced by culturing cells in medium containing 2% serum instead of 10% serum. The {sup 32}P label was completely removed from the protein by treatment with snake venom phosphodiesterase and the digestion product was identified as ({sup 32}P)AMP, indicating the protein was mono-ADP-ribosylated. HPLC analysis of tryptic peptides of the {sup 32}P-labeled 97-kDa protein and purified EF-2, which was ADP-ribosylated in vitro with diphtheria toxin fragment A and ({sup 32}P)NAD, demonstrated an identical labeled peptide in the two proteins. The data strongly suggest that EF-2 was endogenously ADP-ribosylated in pyBHK cells. Maximum incorporation of radioactivity in EF-2 occurred by 12 hr and remained constant over the subsequent 12 hr. It was estimated that 30-35% of the EF-2 was ADP-ribosylated in cells cultured in medium containing 2% serum. When {sup 32}P-labeled cultures were incubated in medium containing unlabeled phosphate, the {sup 32}P label was lost from the EF-2 within 30 min.

Rhizome elongation and seagrass clonal growth

NARCIS (Netherlands)

Marbà, N.; Duarte, C.M.

1998-01-01

A compilation of published and original data on rhizome morphometry, horizontal and vertical elongation rates and branching patterns for 27 seagrass species developing in 192 seagrass stands allowed an examination of the variability of seagrass rhizome and clonal growth programmes across and within

2'-O-methylation in mRNA disrupts tRNA decoding during translation elongation.

Science.gov (United States)

Choi, Junhong; Indrisiunaite, Gabriele; DeMirci, Hasan; Ieong, Ka-Weng; Wang, Jinfan; Petrov, Alexey; Prabhakar, Arjun; Rechavi, Gideon; Dominissini, Dan; He, Chuan; Ehrenberg, Måns; Puglisi, Joseph D

2018-03-01

Chemical modifications of mRNA may regulate many aspects of mRNA processing and protein synthesis. Recently, 2'-O-methylation of nucleotides was identified as a frequent modification in translated regions of human mRNA, showing enrichment in codons for certain amino acids. Here, using single-molecule, bulk kinetics and structural methods, we show that 2'-O-methylation within coding regions of mRNA disrupts key steps in codon reading during cognate tRNA selection. Our results suggest that 2'-O-methylation sterically perturbs interactions of ribosomal-monitoring bases (G530, A1492 and A1493) with cognate codon-anticodon helices, thereby inhibiting downstream GTP hydrolysis by elongation factor Tu (EF-Tu) and A-site tRNA accommodation, leading to excessive rejection of cognate aminoacylated tRNAs in initial selection and proofreading. Our current and prior findings highlight how chemical modifications of mRNA tune the dynamics of protein synthesis at different steps of translation elongation.

Elongation-related functions of LEAFY COTYLEDON1 during the development of Arabidopsis thaliana.

Science.gov (United States)

Junker, Astrid; Mönke, Gudrun; Rutten, Twan; Keilwagen, Jens; Seifert, Michael; Thi, Tuyet Minh Nguyen; Renou, Jean-Pierre; Balzergue, Sandrine; Viehöver, Prisca; Hähnel, Urs; Ludwig-Müller, Jutta; Altschmied, Lothar; Conrad, Udo; Weisshaar, Bernd; Bäumlein, Helmut

2012-08-01

The transcription factor LEAFY COTYLEDON1 (LEC1) controls aspects of early embryogenesis and seed maturation in Arabidopsis thaliana. To identify components of the LEC1 regulon, transgenic plants were derived in which LEC1 expression was inducible by dexamethasone treatment. The cotyledon-like leaves and swollen root tips developed by these plants contained seed-storage compounds and resemble the phenotypes produced by increased auxin levels. In agreement with this, LEC1 was found to mediate up-regulation of the auxin synthesis gene YUCCA10. Auxin accumulated primarily in the elongation zone at the root-hypocotyl junction (collet). This accumulation correlates with hypocotyl growth, which is either inhibited in LEC1-induced embryonic seedlings or stimulated in the LEC1-induced long-hypocotyl phenotype, therefore resembling etiolated seedlings. Chromatin immunoprecipitation analysis revealed a number of phytohormone- and elongation-related genes among the putative LEC1 target genes. LEC1 appears to be an integrator of various regulatory events, involving the transcription factor itself as well as light and hormone signalling, especially during somatic and early zygotic embryogenesis. Furthermore, the data suggest non-embryonic functions for LEC1 during post-germinative etiolation. © 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.

Risk factors for the acquisition of carbapenem-resistant Escherichia coli at a tertiary care center in South Korea: a matched case-control study.

Science.gov (United States)

Ahn, Jin Young; Song, Je Eun; Kim, Min Hyung; Choi, Heun; Kim, Jae Kyung; Ann, Hea Won; Kim, Jung Ho; Jeon, Yongduk; Jeong, Su Jin; Kim, Sun Bean; Ku, Nam Su; Han, Sang Hoon; Song, Young Goo; Yong, Dongeun; Lee, Kyungwon; Kim, June Myung; Choi, Jun Yong

2014-06-01

Carbapenem resistance among gram-negative bacilli is an emerging threat worldwide. The objective of this study was to identify risk factors for the acquisition of carbapenem-resistant Escherichia coli (CRE). We conducted a matched case-control study comprising 57 cases of acquisition of CRE and 114 controls (1:2 matched) selected from patients with a culture of carbapenem-susceptible E coli between January 2006 and December 2010 at a 2000-bed tertiary care center in South Korea. On univariate analysis, previous use of carbapenem (P carbapenem (odds ratio [OR], 4.56; 95% confidence interval [CI] 1.44-14.46; P = .01) and previous use of fluoroquinolone (OR, 2.81; 95% CI, 1.14-6.99; P = .03) were independent risk factors. At this institute, the antibiotic selective pressure of carbapenems and fluoroquinolones was shown to be an important risk factor for the acquisition of CRE. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

Translation elongation factor EF-Tu modulates filament formation of actin-like MreB protein in vitro.

Science.gov (United States)

Defeu Soufo, Hervé Joël; Reimold, Christian; Breddermann, Hannes; Mannherz, Hans G; Graumann, Peter L

2015-04-24

EF-Tu has been shown to interact with actin-like protein MreB and to affect its localization in Escherichia coli and in Bacillus subtilis cells. We have purified YFP-MreB in an active form, which forms filaments on glass slides in vitro and was active in dynamic light-scattering assays, polymerizing in milliseconds after addition of magnesium. Purified EF-Tu enhanced the amount of MreB filaments, as seen by sedimentation assays, the speed of filament formation and the length of MreB filaments in vitro. EF-Tu had the strongest impact on MreB filaments in a 1:1 ratio, and EF-Tu co-sedimented with MreB filaments, revealing a stoichiometric interaction between both proteins. This was supported by cross-linking assays where 1:1 species were well detectable. When expressed in E. coli cells, B. subtilis MreB formed filaments and induced the formation of co-localizing B. subtilis EF-Tu structures, indicating that MreB can direct the positioning of EF-Tu structures in a heterologous cell system. Fluorescence recovery after photobleaching analysis showed that MreB filaments have a higher turnover in B. subtilis cells than in E. coli cells, indicating different filament kinetics in homologous or heterologous cell systems. The data show that MreB can direct the localization of EF-Tu in vivo, which in turn positively affects the formation and dynamics of MreB filaments. Thus, EF-Tu is a modulator of the activity of a bacterial actin-like protein. Copyright © 2015. Published by Elsevier Ltd.

[Risk factors associated with the isolation of extended spectrum betalactamases producing Escherichia coli or Klebsiella pneumoniae in a tertiary care hospital in Colombia].

Science.gov (United States)

Jiménez, Adriana; Alvarado, Alejandra; Gómez, Felipe; Carrero, Germán; Fajardo, Claudia

2014-04-01

Extended-spectrum beta-lactamases (ESBL) are an emerging resistance phenomenon with particular incidence in Latin America. In Colombia there is very little information regarding the risk factors associated with its acquisition. To determine the risk factors that are associated with infection or colonization by Escherichia coli or Klebsiella pneumoniae producing ESBL in patients older than 18 years. A case-control study, ratio 1:1, in patients with an isolate from any sample of E. coli or K. pneumoniae producing ESBL in the period from January 2009 to November 2011 at San José University Hospital in Bogotá (Colombia). We studied 110 cases and 110 controls, 62.7% were E. coli and 37.3% K. pneumoniae . In the multivariate analysis the independent risk factors found were: chronic renal failure (odds ratio [OR] 2.99, confidence interval 95% [95% CI] 1.10-8.11, p=0.031), urologic surgery (OR 4.78 95% CI 1.35 to 16.87, p=0.015), history of antibiotic use in the previous three months (OR 2.24, 95% CI 1.09 – 4.60, p=0.028), nosocomial origin of infection (OR=2.92 95% CI 1.39 – 6.13, p=0.004) and previous hospitalization (OR 1,59, 95% CI=1.03 – 2.46, p=0,036). Anticipating the resistance pattern of the organism infecting a patient based on risk factors may allow the choice of appropriate empirical antibiotic therapy, which will have an impact on reducing patients' morbidity and mortality.

Vaginal versus Obstetric Infection Escherichia coli Isolates among Pregnant Women: Antimicrobial Resistance and Genetic Virulence Profile.

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Emma Sáez-López

Full Text Available Vaginal Escherichia coli colonization is related to obstetric infections and the consequent development of infections in newborns. Ampicillin resistance among E. coli strains is increasing, which is the main choice for treating empirically many obstetric and neonatal infections. Vaginal E. coli strains are very similar to extraintestinal pathogenic E. coli with regards to the virulence factors and the belonging to phylogroup B2. We studied the antimicrobial resistance and the genetic virulence profile of 82 E. coli isolates from 638 vaginal samples and 63 isolated from endometrial aspirate, placental and amniotic fluid samples from pregnant women with obstetric infections. The prevalence of E. coli in the vaginal samples was 13%, which was significant among women with associated risk factors during pregnancy, especially premature preterm rupture of membranes (p<0.0001. Sixty-five percent of the strains were ampicillin-resistant. The E. coli isolates causing obstetric infections showed higher resistance levels than vaginal isolates, particularly for gentamicin (p = 0.001. The most prevalent virulence factor genes were those related to the iron uptake systems revealing clear targets for interventions. More than 50% of the isolates belonged to the virulent B2 group possessing the highest number of virulence factor genes. The ampicillin-resistant isolates had high number of virulence factors primarily related to pathogenicity islands, and the remarkable gentamicin resistance in E. coli isolates from women presenting obstetric infections, the choice of the most appropriate empiric treatment and clinical management of pregnant women and neonates should be carefully made. Taking into account host-susceptibility, the heterogeneity of E. coli due to evolution over time and the geographical area, characterization of E. coli isolates colonizing the vagina and causing obstetric infections in different regions may help to develop interventions and avoid the

Escherichia coli pathotypes

Science.gov (United States)

Escherichia coli strains are important commensals of the intestinal tract of humans and animals; however, pathogenic strains, including diarrhea-inducing E. coli and extraintestinal pathogenic E. coli. Intestinal E. coli pathotypes may cause a dehydrating watery diarrhea, or more severe diseases su...

Virulence factors of Escherichia coli in relation to the importance of vaccination in pigs

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Daniele Araujo Pereira

2016-08-01

Full Text Available ABSTRACT: Enterotoxigenic Escherichia coli (ETEC is the major cause of diarrhea in newborn and weaned pigs. Bacteria adhesion to the host cell is considered a specific phenomenon among fimbrial and non-fimbrial adhesins with their respective receptors on enterocytes. Enteric disorders are related with the fimbriae F4 (K88, F5 (K99, F6 (987P, F41, and F18. In addition to ETEC, another category of E. coli , porcine pathogenic E. coli (PEPEC,can cause diarrhea in pigs; it produces the porcine attaching and effacing-associated (Paa adhesin in, which is capable to cause a typical lesion known as an attaching and effacing (A/E lesion. Immunization of sows with adhesin is important to stimulate the production of antibodies and their subsequent transfer to piglets through colostrum. The aim of this paper is to illustrate the main impacts of enteric diseases caused by E. coli in swine production and to highlight the importance of continuing research on this bacterium to improve disease prevention through vaccination.

Eukaryotic elongation factor 1-beta interacts with the 5' untranslated region of the M gene of Nipah virus to promote mRNA translation.

Science.gov (United States)

Uchida, Shotaro; Sato, Hiroki; Yoneda, Misako; Kai, Chieko

2016-09-01

Nipah virus belongs to the genus Henipavirus in the family Paramyxoviridae, and its RNA genome is larger than those of other paramyxoviruses because it has long untranslated regions (UTRs) in each gene. However, the functions of these UTRs are not fully understood. In this study, we investigated the functions of the 5' UTRs and found that the 5' UTR of the M gene upregulated the translation of a reporter gene. Using an RNA pull-down assay, we showed that eukaryotic elongation factor 1-beta (EEF1B2) interacts with nucleotides 81-100 of the M 5' UTR and specifically enhances its translation efficiency. Our results suggest that the M 5' UTR promotes the production of M protein and viral budding by recruiting EEF1B2.

Growth Factor Inhibiting PKC Sensor in E-coli Environment Using Classification Technique and ANN Method

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T. K. BASAK

2011-03-01

Full Text Available Protein kinease C plays an important role in angiogenesis and apoptosis in cancer. During the phase of angiogenesis the growth factor is up regulated where as during apoptosis the growth factor is down regulated. For down regulation of growth factor the pH environment of intra-cellular fluid has a specific range in the alkaline medium. Protein kinease C along with E-coli through interaction of Selenometabolite is able to maintain that alkaline environment for the apoptosis of the cancer cell with inhibition of the growth factor related to antioxidant/oxidant ratio. The present paper through implementation of Artificial Neural Network and Decision Tree has focused on metastasis linked with Capacitance Relaxation phenomena and down regulation of growth factor (VGEF. In this paper a distributed neural network has been applied to a data mining problem for classification of cancer stages inorder to have proper diagnosis of patient with PKC sensor. The Network was trained off line using 270 patterns each of 6 inputs. Using the weight obtained during training, fresh patterns were tested for accuracy in diagnosis linked with the stages of cancer.

Analysis of early-onset bloodstream infection due to Escherichia coli infection in premature babies

OpenAIRE

Chen, I-Lun; Huang, Hsin-Chun; Wu, Chih-Te; Ou-Yang, Mei-Chen; Chung, Mei-Yung; Chen, Chih-Cheng; Suen, Jau-Ling; Hung, Chih-Hsing

2017-01-01

Abstract In early-onset bacteremia among preterm neonates, Escherichia coli (E. coli) is the main pathogen and can cause a high mortality rate. Thus, the predictive factors of mortality and extended-spectrum ?-lactamase (ESBL)-producing E. coli in preterm babies with E. coli early-onset bacteremia were reported. We retrospectively reviewed preterm neonates who had E. coli bacteremia occurring within 3 days after birth between 2004 and 2015. Maternal and perinatal information were collected fr...

Differential expression of the Escherichia coli autoaggregation factor antigen 43

DEFF Research Database (Denmark)

Schembri, Mark; Hjerrild, Louise; Gjermansen, Morten

2003-01-01

Antigen 43 (Ag43) is a self-recognizing surface adhesin found in most Escherichia coli strains. Due to its excellent cell-to-cell aggregation characteristics, Ag43 expression confers clumping and fluffing of cells and promotes biofilm formation. Ag43 expression is repressed by the cellular redox...

EUI1, encoding a putative cytochrome P450 monooxygenase, regulates internode elongation by modulating gibberellin responses in rice.

Science.gov (United States)

Luo, Anding; Qian, Qian; Yin, Hengfu; Liu, Xiaoqiang; Yin, Changxi; Lan, Ying; Tang, Jiuyou; Tang, Zuoshun; Cao, Shouyun; Wang, Xiujie; Xia, Kai; Fu, Xiangdong; Luo, Da; Chu, Chengcai

2006-02-01

Elongation of rice internodes is one of the most important agronomic traits, which determines the plant height and underlies the grain yield. It has been shown that the elongation of internodes is under genetic control, and various factors are implicated in the process. Here, we report a detailed characterization of an elongated uppermost internode1 (eui1) mutant, which has been used in hybrid rice breeding. In the eui1-2 mutant, the cell lengths in the uppermost internodes are significantly longer than that of wild type and thus give rise to the elongated uppermost internode. It was found that the level of active gibberellin was elevated in the mutant, whereas its growth in response to gibberellin is similar to that of the wild type, suggesting that the higher level accumulation of gibberellin in the eui1 mutant causes the abnormal elongation of the uppermost internode. Consistently, the expression levels of several genes which encode gibberellin biosynthesis enzymes were altered. We cloned the EUI1 gene, which encodes a putative cytochrome P450 monooxygenase, by map-based cloning and found that EUI1 was weakly expressed in most tissues, but preferentially in young panicles. To confirm its function, transgenic experiments with different constructs of EUI1 were conducted. Overexpression of EUI1 gave rise to the gibberellin-deficient-like phenotypes, which could be partially reversed by supplementation with gibberellin. Furthermore, apart from the alteration of expression levels of the gibberellin biosynthesis genes, accumulation of SLR1 protein was found in the overexpressing transgenic plants, indicating that the expression level of EUI1 is implicated in both gibberellin-mediated SLR1 destruction and a feedback regulation in gibberellin biosynthesis. Therefore, we proposed that EUI1 plays a negative role in gibberellin-mediated regulation of cell elongation in the uppermost internode of rice.

Strigolactones Stimulate Internode Elongation Independently of Gibberellins1[C][W

Science.gov (United States)

de Saint Germain, Alexandre; Ligerot, Yasmine; Dun, Elizabeth A.; Pillot, Jean-Paul; Ross, John J.; Beveridge, Christine A.; Rameau, Catherine

2013-01-01

Strigolactone (SL) mutants in diverse species show reduced stature in addition to their extensive branching. Here, we show that this dwarfism in pea (Pisum sativum) is not attributable to the strong branching of the mutants. The continuous supply of the synthetic SL GR24 via the root system using hydroponics can restore internode length of the SL-deficient rms1 mutant but not of the SL-response rms4 mutant, indicating that SLs stimulate internode elongation via RMS4. Cytological analysis of internode epidermal cells indicates that SLs control cell number but not cell length, suggesting that SL may affect stem elongation by stimulating cell division. Consequently, SLs can repress (in axillary buds) or promote (in the stem) cell division in a tissue-dependent manner. Because gibberellins (GAs) increase internode length by affecting both cell division and cell length, we tested if SLs stimulate internode elongation by affecting GA metabolism or signaling. Genetic analyses using SL-deficient and GA-deficient or DELLA-deficient double mutants, together with molecular and physiological approaches, suggest that SLs act independently from GAs to stimulate internode elongation. PMID:23943865

Identification of genes required for growth of Escherichia coli MG1655 at moderately low pH

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Bram Vivijs

2016-10-01

Full Text Available The survival of some pathotypes of E. coli in very low pH environments like highly acidic foods and the stomach has been well documented and contributes to their success as foodborne pathogens. In contrast, the ability of E. coli to grow at moderately low pH has received less attention, although this property can be anticipated to be also very important for the safety of mildly acidic foods. Therefore, the objective of this study was to identify cellular functions required for growth of the non-pathogenic strain E. coli MG1655 at low pH. First, the role of the four E. coli amino acid decarboxylase systems, which are the major cellular mechanisms allowing extreme acid survival, was investigated using mutants defective in each of the systems. Only the lysine decarboxylase (CadA was required for low pH growth. Secondly, a screening of 8544 random transposon insertion mutants resulted in the identification of six genes affecting growth in LB broth acidified to pH 4.50 with HCl. Two of the genes, encoding the transcriptional regulator LeuO and the elongation factor P-β-lysine ligase EpmA, can be linked to CadA production. Two other genes, encoding the diadenosine tetraphosphatase ApaH and the tRNA modification GTPase MnmE, have been previously implicated in the bacterial response to stresses other than low pH. A fifth gene encodes the LPS heptosyltransferase WaaC, and its mutant has a deep rough colony phenotype, which has been linked to reduced acid tolerance in earlier work. Finally, tatC encodes a secA-independent protein translocase that exports a few dozen proteins and thus is likely to have a pleiotropic phenotype. For mnmE, apaH, epmA,and waaC, de novo in frame deletion and genetic complementation confirmed their role in low pH growth, and these deletion mutants were also affected in growth in apple juice and tomato juice. However, the mutants were not affected in survival in gastric simulation medium at pH 2.5, indicating that growth at

Direct interaction of FtsZ and MreB is required for septum synthesis and cell division in Escherichia coli.

Science.gov (United States)

Fenton, Andrew K; Gerdes, Kenn

2013-07-03

How bacteria coordinate cell growth with division is not well understood. Bacterial cell elongation is controlled by actin-MreB while cell division is governed by tubulin-FtsZ. A ring-like structure containing FtsZ (the Z ring) at mid-cell attracts other cell division proteins to form the divisome, an essential protein assembly required for septum synthesis and cell separation. The Z ring exists at mid-cell during a major part of the cell cycle without contracting. Here, we show that MreB and FtsZ of Escherichia coli interact directly and that this interaction is required for Z ring contraction. We further show that the MreB-FtsZ interaction is required for transfer of cell-wall biosynthetic enzymes from the lateral to the mature divisome, allowing cells to synthesise the septum. Our observations show that bacterial cell division is coupled to cell elongation via a direct and essential interaction between FtsZ and MreB.

The Drosophila mitochondrial translation elongation factor G1 contains a nuclear localization signal and inhibits growth and DPP signaling.

Science.gov (United States)

Trivigno, Catherine; Haerry, Theodor E

2011-02-25

Mutations in the human mitochondrial elongation factor G1 (EF-G1) are recessive lethal and cause death shortly after birth. We have isolated mutations in iconoclast (ico), which encodes the highly conserved Drosophila orthologue of EF-G1. We find that EF-G1 is essential during fly development, but its function is not required in every tissue. In contrast to null mutations, missense mutations exhibit stronger, possibly neomorphic phenotypes that lead to premature death during embryogenesis. Our experiments show that EF-G1 contains a secondary C-terminal nuclear localization signal. Expression of missense mutant forms of EF-G1 can accumulate in the nucleus and cause growth and patterning defects and animal lethality. We find that transgenes that encode mutant human EF-G1 proteins can rescue ico mutants, indicating that the underlying problem of the human disease is not just the loss of enzymatic activity. Our results are consistent with a model where EF-G1 acts as a retrograde signal from mitochondria to the nucleus to slow down cell proliferation if mitochondrial energy output is low.

Expression of Vibrio harveyi acyl-ACP synthetase allows efficient entry of exogenous fatty acids into the Escherichia coli fatty acid and lipid A synthetic pathways.

Science.gov (United States)

Jiang, Yanfang; Morgan-Kiss, Rachael M; Campbell, John W; Chan, Chi Ho; Cronan, John E

2010-02-02

Although the Escherichia coli fatty acid synthesis (FAS) pathway is the best studied type II fatty acid synthesis system, a major experimental limitation has been the inability to feed intermediates into the pathway in vivo because exogenously supplied free fatty acids are not efficiently converted to the acyl-acyl carrier protein (ACP) thioesters required by the pathway. We report that expression of Vibrio harveyi acyl-ACP synthetase (AasS), a soluble cytosolic enzyme that ligates free fatty acids to ACP to form acyl-ACPs, allows exogenous fatty acids to enter the E. coli fatty acid synthesis pathway. The free fatty acids are incorporated intact and can be elongated or directly incorporated into complex lipids by acyltransferases specific for acyl-ACPs. Moreover, expression of AasS strains and supplementation with the appropriate fatty acid restored growth to E. coli mutant strains that lack essential fatty acid synthesis enzymes. Thus, this strategy provides a new tool for circumventing the loss of enzymes essential for FAS function.

Ecological and genetic determinants of plasmid distribution in Escherichia coli.

Science.gov (United States)

Medaney, Frances; Ellis, Richard J; Raymond, Ben

2016-11-01

Bacterial plasmids are important carriers of virulence and antibiotic resistance genes. Nevertheless, little is known of the determinants of plasmid distribution in bacterial populations. Here the factors affecting the diversity and distribution of the large plasmids of Escherichia coli were explored in cattle grazing on semi-natural grassland, a set of populations with low frequencies of antibiotic resistance genes. Critically, the population genetic structure of bacterial hosts was chararacterized. This revealed structured E. coli populations with high diversity between sites and individuals but low diversity within cattle hosts. Plasmid profiles, however, varied considerably within the same E. coli genotype. Both ecological and genetic factors affected plasmid distribution: plasmid profiles were affected by site, E. coli diversity, E. coli genotype and the presence of other large plasmids. Notably 3/26 E. coli serotypes accounted for half the observed plasmid-free isolates indicating that within species variation can substantially affect carriage of the major conjugative plasmids. The observed population structure suggest that most of the opportunities for within species plasmid transfer occur between different individuals of the same genotype and support recent experimental work indicating that plasmid-host coevolution, and epistatic interactions on fitness costs are likely to be important in determining occupancy. © 2016 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

Analysis of cracking potential and micro-elongation of linerboard

Directory of Open Access Journals (Sweden)

Supattra Panthai

2016-11-01

Full Text Available Folding cracks of linerboards in relation to their micro-elongation and the forming conditions were studied using an industrial linerboard machine with a top former. The experiments consisted of the study of various forming conditions by manipulating the jet/wire speed ratio to produce linerboard with differences in fiber structures that were related to the cracked and uncracked products. The results showed that changes to the jet/wire speed ratio of about 0.01–0.02 to improve the tested folding endurance in the machine direction potentially produced folding cracks in the linerboard, which indicated an ambiguous interpretation of the foldability tests. The delaminated cracked layers were found to have a high folding endurance and tensile strength, while the decrease in the micro-elongation formulated in this study was found to be related to cracking. A lower micro-elongation of about 350–500 μm/N·g was found in a range of products with folding cracks.

Research on killing Escherichia Coli by reactive oxygen species based on strong ionization discharging plasma

International Nuclear Information System (INIS)

Li, Y J; Tian, Y P; Zhang, Z T; Li, R H; Cai, L J; Gao, J Y

2013-01-01

Reactive oxygen species solution produced by strong ionization discharging plasma was used to kill Escherichia coli by spraying. Several effect factors such as pH value, solution temperature, spraying time and exposure time were observed in this study, and their effects on killing rate of Escherichia coli were discussed and analysed. Results show that the treating efficiency of ROS solution for Escherichia coli is higher in alkaline solution than that in acid solution. The killing rate of Escherichia coli increases while the spraying time and exposure time are longer and the temperature is lower. The effects of different factors on killing rate of Escherichia coli are as follows: spraying time > pH value > exposure time > solution temperature.

On the decrease of ultimate elongation of gum elastomer by irradiation

International Nuclear Information System (INIS)

Ito, Masayuki

1986-01-01

The reason why the ultimate elongation of gum elastomer decreases by irradiation was studied. The sample used is tetrafluoroethylenepropylene copolymer vulcanized which is a heat resistant elastomer. The sample was irradiated by a electron beam at room temperature. Cross-linking predominate in the operation. (Case 1) Scission predominant condition (Case 2) was given by irradiation of Co-60 γ ray at 100 deg C. Alternative irradiation of γ ray and electron beam under above condition can keep the original cross-linking density by the appropriate choice of each of the doses. (Case 3) The three cases mentioned above involve all of the cases of radiation induced aging of elastomers. Therefor, the following explanation for three cases shows the reason why the ultimate elongation of gum elastomer decreases by irradiation. Case 1. Cross-linking predominant condition. Ultimate elongation is proportional to -0.5 power of the dose. This fact can be explicable by the model of Buche, i.e. the breaking of a short chain causes another to break and that so on throughout the whole sample. Case 2. Chain scission predominant condition. Ultimate elongation increases by irradiation for a certain dose. This fact can understand by the model of Buche. But from a certain dose ultimate elongation does not increase. In the period the structure of the sample turned to be the same structure as the low molecular weight amorphose polymer vulcanized. Case 3. Rate of cross-linking and scission is the same. The average chain length does not chainge in the condition. But the distribution of chain length became wider and wider by irradiation. The increase of short chain result the decrease in ultimate elongation. (author)

Mitochondrial Respiration Inhibitors Suppress Protein Translation and Hypoxic Signaling via the Hyperphosphorylation and Inactivation of Translation Initiation Factor eIF2α and Elongation Factor eEF2

Science.gov (United States)

Li, Jun; Mahdi, Fakhri; Du, Lin; Datta, Sandipan; Nagle, Dale G.; Zhou, Yu-Dong

2011-01-01

Over 20000 lipid extracts of plants and marine organisms were evaluated in a human breast tumor T47D cell-based reporter assay for hypoxia-inducible factor-1 (HIF-1) inhibitory activity. Bioassay-guided isolation and dereplication-based structure elucidation of an active extract from the Bael tree (Aegle marmelos) afforded two protolimonoids, skimmiarepin A (1) and skimmiarepin C (2). In T47D cells, 1 and 2 inhibited hypoxia-induced HIF-1 activation with IC50 values of 0.063 µM and 0.068 µM, respectively. Compounds 1 and 2 also suppressed hypoxic induction of the HIF-1 target genes GLUT-1 and VEGF. Mechanistic studies revealed that 1 and 2 inhibited HIF-1 activation by blocking the hypoxia-induced accumulation of HIF-1α protein. At the range of concentrations that inhibited HIF-1 activation, 1 and 2 suppressed cellular respiration by selectively inhibiting the mitochondrial electron transport chain at complex I (NADH dehydrogenase). Further investigation indicated that mitochondrial respiration inhibitors such as 1 and rotenone induced the rapid hyperphosphorylation and inhibition of translation initiation factor eIF2α and elongation factor eEF2. The inhibition of protein translation may account for the short-term exposure effects exerted by mitochondrial inhibitors on cellular signaling, while the suppression of cellular ATP production may contribute to the inhibitory effects following extended treatment periods. PMID:21875114

Endogenous abscisic acid as a key switch for natural variation in flooding-induced shoot elongation.

Science.gov (United States)

Chen, Xin; Pierik, Ronald; Peeters, Anton J M; Poorter, Hendrik; Visser, Eric J W; Huber, Heidrun; de Kroon, Hans; Voesenek, Laurentius A C J

2010-10-01

Elongation of leaves and stem is a key trait for survival of terrestrial plants during shallow but prolonged floods that completely submerge the shoot. However, natural floods at different locations vary strongly in duration and depth, and, therefore, populations from these locations are subjected to different selection pressure, leading to intraspecific variation. Here, we identified the signal transduction component that causes response variation in shoot elongation among two accessions of the wetland plant Rumex palustris. These accessions differed 2-fold in petiole elongation rates upon submergence, with fast elongation found in a population from a river floodplain and slow elongation in plants from a lake bank. Fast petiole elongation under water consumes carbohydrates and depends on the (inter)action of the plant hormones ethylene, abscisic acid, and gibberellic acid. We found that carbohydrate levels and dynamics in shoots did not differ between the fast and slow elongating plants, but that the level of ethylene-regulated abscisic acid in petioles, and hence gibberellic acid responsiveness of these petioles explained the difference in shoot elongation upon submergence. Since this is the exact signal transduction level that also explains the variation in flooding-induced shoot elongation among plant species (namely, R. palustris and Rumex acetosa), we suggest that natural selection results in similar modification of regulatory pathways within and between species.

Experimental results on elongation control using dynamic input allocation at FTU

International Nuclear Information System (INIS)

Varano, G.; Boncagni, L.; Galeani, S.; Granucci, G.; Vitale, V.; Zaccarian, L.

2011-01-01

We report on the experimental results related to a recently proposed control scheme for the regulation of plasma elongation using the poloidal field coils available at FTU, already used for the horizontal position control. The proposed technique allows to realize elongation regulation as a secondary task using the same poloidal coils.

Effect of stress induced by suboptimal growth factors on survival of Escherichia coli O157:H7.

Science.gov (United States)

Uyttendaele, M; Taverniers, I; Debevere, J

2001-05-21

This study investigated the growth and survival of E. coli O157:H7 exposed to a combination of suboptimal factors (22 degrees C, 7 degrees C, -18 degrees C/0.5% NaCl, 5.0% NaCl/pH 7.0, pH 5.4, pH 4.5/addition of lactic acid) in a simulation medium for red meat (beef gravy). Prolonged survival was noted as the imposed stress was more severe, and as multiple growth factors became suboptimal. At a defined temperature (7 degrees C or -18 degrees C), survival was prolonged at the more acid, more suboptimal pH (pH 4.5 > pH 5.4 > pH 7.0) while at a defined pH (pH 4.5), better survival was observed at 7 degrees C than at 22 degrees C. This suggests that application of the hurdle concept for preservation of food may inhibit outgrowth but induce prolonged survival of E. coli O157:H7 in minimal processed foods. At both 22 degrees C and 7 degrees C, the addition of lactic acid instead of HCl to reduce pH (to pH 4.5) resulted in a more rapid decrease of E. coli O157:H7. High survival was observed in beef gravy, pH 5.4 at -18 degrees C (simulation of frozen meat)-reduction of log 3.0 to log 1.9 after 43 days--and in beef gravy, pH 4.5 and 5% NaCl at 7 degrees C (simulation of a fermented dried meat product kept in refrigeration)--less than 1 log reduction in 43 days. In these circumstances, however, a high degree of sublethal damage of the bacterial cells was noted. The degree of sublethal damage can be estimated from the difference in recovery of the pathogen on the non-selective TSA medium and the selective SMAC medium.

Vaginal versus Obstetric Infection Escherichia coli Isolates among Pregnant Women: Antimicrobial Resistance and Genetic Virulence Profile.

Science.gov (United States)

Sáez-López, Emma; Guiral, Elisabet; Fernández-Orth, Dietmar; Villanueva, Sonia; Goncé, Anna; López, Marta; Teixidó, Irene; Pericot, Anna; Figueras, Francesc; Palacio, Montse; Cobo, Teresa; Bosch, Jordi; Soto, Sara M

2016-01-01

Vaginal Escherichia coli colonization is related to obstetric infections and the consequent development of infections in newborns. Ampicillin resistance among E. coli strains is increasing, which is the main choice for treating empirically many obstetric and neonatal infections. Vaginal E. coli strains are very similar to extraintestinal pathogenic E. coli with regards to the virulence factors and the belonging to phylogroup B2. We studied the antimicrobial resistance and the genetic virulence profile of 82 E. coli isolates from 638 vaginal samples and 63 isolated from endometrial aspirate, placental and amniotic fluid samples from pregnant women with obstetric infections. The prevalence of E. coli in the vaginal samples was 13%, which was significant among women with associated risk factors during pregnancy, especially premature preterm rupture of membranes (pinfections showed higher resistance levels than vaginal isolates, particularly for gentamicin (p = 0.001). The most prevalent virulence factor genes were those related to the iron uptake systems revealing clear targets for interventions. More than 50% of the isolates belonged to the virulent B2 group possessing the highest number of virulence factor genes. The ampicillin-resistant isolates had high number of virulence factors primarily related to pathogenicity islands, and the remarkable gentamicin resistance in E. coli isolates from women presenting obstetric infections, the choice of the most appropriate empiric treatment and clinical management of pregnant women and neonates should be carefully made. Taking into account host-susceptibility, the heterogeneity of E. coli due to evolution over time and the geographical area, characterization of E. coli isolates colonizing the vagina and causing obstetric infections in different regions may help to develop interventions and avoid the aetiological link between maternal carriage and obstetric and subsequent puerperal infections.

Bacteraemia Caused by Escherichia Coli in Cancer Patients at a Specialist Center in Pakistan

International Nuclear Information System (INIS)

Parveen, A.; Sultan, F.; Saleem, S.; Nazeer, S. H.; Raza, A.; Zafar, W.; Nizamuddin, S.; Mahboob, A.

2015-01-01

Objective: To analyse the antimicrobial susceptibility patterns of Escherichia coli bacteraemia among cancer patients, and to assess the risk factors and outcomes of multidrug-resistant Escherichia coli bacteraemia. Methods: The retrospective study was conducted at Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore, and comprised medical records of patients with Escherichia coli bacteraemia presenting between December 2012 and November 2013. Multivariable logistic regression analyses were used to determine the factors associated with the development and 30-day mortality of multidrug-resistant Escherichia coli bacteraemia. Results: Out of 1603 episodes of bacteraemia, 227(35.6 percent) were caused by E.coli, of which 98(43.2 percent) were multidrug-resistant. In multivariable analysis, age less than 18 years (adjusted odds ratio 3.92; 95 percent confidence interval 1.43-10.68), presence of central venous catheter (adjusted odds ratio 2.12; 95 percent confidence interval 1.04-4.33) and exposure to piperacillin/tazobactam within 90 days prior to infection (adjusted odds ratio 2.37; 95 percent confidence interval 1.15-4.86) were identified as independent risk factors for acquisition of multidrug-resistant Escherichia coli bacteraemia. The overall 30 day mortality rate was 35.2 percent (80/227). Risk factors for mortality were intensive care unit admission (adjusted odds ratio 3.95; 95 percent confidence interval 1.79-8.71) and profound neutropenia (adjusted odds ratio 4.03; 95 percent confidence interval 1.55-10.49). Conclusion: Bloodstream infections with multidrug-resistant Escherichia coli were common in cancer patients. However it was not a predictor of mortality. (author)

Gradual nerve elongation affects nerve cell bodies and neuro-muscular junctions.

Science.gov (United States)

Kazuo Ikeda, K I; Masaki Matsuda, M M; Daisuke Yamauchi, D Y; Katsuro Tomita, K T; Shigenori Tanaka, S T

2005-07-01

The purpose of this study is to clarify the reactions of the neuro-muscular junction and nerve cell body to gradual nerve elongation. The sciatic nerves of Japanese white rabbits were lengthened by 30 mm in increments of 0.8 mm/day, 2.0 mm/day and 4.0 mm/day. A scanning electron microscopic examination showed no degenerative change at the neuro-muscular junction, even eight weeks after elongation in the 4-mm group. Hence, neuro-muscular junction is not critical for predicting damage from gradual nerve elongation. There were no axon reaction cells in the 0.8-mm group, a small amount in the 2-mm group, and a large amount in the 4-mm group. The rate of growth associated protein-43 positive nerve cells was significant in the 4-mm group. Hence, the safe speed for nerve cells appeared to be 0.8-mm/day, critical speed to be 2.0-mm/day, and dangerous speed to be 4.0-mm/day in this elongation model.

Elongational flow of polymer melts at constant strain rate, constant stress and constant force

Science.gov (United States)

Wagner, Manfred H.; Rolón-Garrido, Víctor H.

2013-04-01

Characterization of polymer melts in elongational flow is typically performed at constant elongational rate or rarely at constant tensile stress conditions. One of the disadvantages of these deformation modes is that they are hampered by the onset of "necking" instabilities according to the Considère criterion. Experiments at constant tensile force have been performed even more rarely, in spite of the fact that this deformation mode is free from necking instabilities and is of considerable industrial relevance as it is the correct analogue of steady fiber spinning. It is the objective of the present contribution to present for the first time a full experimental characterization of a long-chain branched polyethylene melt in elongational flow. Experiments were performed at constant elongation rate, constant tensile stress and constant tensile force by use of a Sentmanat Extensional Rheometer (SER) in combination with an Anton Paar MCR301 rotational rheometer. The accessible experimental window and experimental limitations are discussed. The experimental data are modelled by using the Wagner I model. Predictions of the steady-start elongational viscosity in constant strain rate and creep experiments are found to be identical, albeit only by extrapolation of the experimental data to Hencky strains of the order of 6. For constant stress experiments, a minimum in the strain rate and a corresponding maximum in the elongational viscosity is found at a Hencky strain of the order of 3, which, although larger than the steady-state value, follows roughly the general trend of the steady-state elongational viscosity. The constitutive analysis also reveals that constant tensile force experiments indicate a larger strain hardening potential than seen in constant elongation rate or constant tensile stress experiments. This may be indicative of the effect of necking under constant elongation rate or constant tensile stress conditions according to the Considère criterion.

Transcription-factor-mediated DNA looping probed by high-resolution, single-molecule imaging in live E. coli cells.

Directory of Open Access Journals (Sweden)

Zach Hensel

Full Text Available DNA looping mediated by transcription factors plays critical roles in prokaryotic gene regulation. The "genetic switch" of bacteriophage λ determines whether a prophage stays incorporated in the E. coli chromosome or enters the lytic cycle of phage propagation and cell lysis. Past studies have shown that long-range DNA interactions between the operator sequences O(R and O(L (separated by 2.3 kb, mediated by the λ repressor CI (accession number P03034, play key roles in regulating the λ switch. In vitro, it was demonstrated that DNA segments harboring the operator sequences formed loops in the presence of CI, but CI-mediated DNA looping has not been directly visualized in vivo, hindering a deep understanding of the corresponding dynamics in realistic cellular environments. We report a high-resolution, single-molecule imaging method to probe CI-mediated DNA looping in live E. coli cells. We labeled two DNA loci with differently colored fluorescent fusion proteins and tracked their separations in real time with ∼40 nm accuracy, enabling the first direct analysis of transcription-factor-mediated DNA looping in live cells. Combining looping measurements with measurements of CI expression levels in different operator mutants, we show quantitatively that DNA looping activates transcription and enhances repression. Further, we estimated the upper bound of the rate of conformational change from the unlooped to the looped state, and discuss how chromosome compaction may impact looping kinetics. Our results provide insights into transcription-factor-mediated DNA looping in a variety of operator and CI mutant backgrounds in vivo, and our methodology can be applied to a broad range of questions regarding chromosome conformations in prokaryotes and higher organisms.

Diarrhea, Urosepsis and Hemolytic Uremic Syndrome Caused by the Same Heteropathogenic Escherichia coli Strain

NARCIS (Netherlands)

Ang, C. Wim; Bouts, Antonia H. M.; Rossen, John W. A.; van der Kuip, Martijn; van Heerde, Marc; Bökenkamp, Arend

2016-01-01

We describe an 8-month-old girl with diarrhea, urosepsis and hemolytic uremic syndrome caused by Escherichia coli. Typing of cultured E. coli strains from urine and blood revealed the presence of virulence factors from multiple pathotypes of E. coli. This case exemplifies the genome plasticity of E.

Global transcriptional regulatory network for Escherichia coli robustly connects gene expression to transcription factor activities

DEFF Research Database (Denmark)

Fang, Xin; Sastry, Anand; Mih, Nathan

2017-01-01

Transcriptional regulatory networks (TRNs) have been studied intensely for >25 y. Yet, even for the Escherichia coli TRN-probably the best characterized TRN-several questions remain. Here, we address three questions: (i) How complete is our knowledge of the E. coli TRN; (ii) how well can we predi...

Rare Case of Polymicrobial Keratitis With Balantidium coli.

Science.gov (United States)

Hazarika, Manali; Pai H, Vijaya; Khanna, Vinay; Reddy, Harish; Tilak, Kriti; Chawla, Kiran

2016-12-01

To report a rare case of polymicrobial keratitis due to Balantidium coli and gram-negative bacteria, Pseudomonas aeruginosa and Klebsiella pneumoniae, in a soft contact lens (CL) wearer. We report a case of CL-related keratitis due to B. coli, P. aeruginosa, and K. pneumoniae. The culture of the corneal scrapings, the CL cleaning solution, and the CL revealed the growth of a rare ciliated parasite, B. coli, along with gram-negative bacteria, namely, P. aeruginosa and K. pneumoniae. The patient was successfully treated with topical broad-spectrum antibiotics and intravenous metronidazole. Polymicrobial keratitis has seldom been reported with B. coli as the causative agent. CL wear can be a risk factor for this infection. Treatment with topical antibiotics may not suffice, and the intravenous route of antiprotozoal drugs may be a useful adjunct. Increasing awareness, early diagnosis, and treatment may improve the final visual outcome.

Neurite outgrowth mediated by translation elongation factor eEF1A1: a target for antiplatelet agent cilostazol.

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Kenji Hashimoto

Full Text Available Cilostazol, a type-3 phosphodiesterase (PDE3 inhibitor, has become widely used as an antiplatelet drug worldwide. A recent second Cilostazol Stroke Prevention Study demonstrated that cilostazol is superior to aspirin for prevention of stroke after an ischemic stroke. However, its precise mechanisms of action remain to be determined. Here, we report that cilostazol, but not the PDE3 inhibitors cilostamide and milrinone, significantly potentiated nerve growth factor (NGF-induced neurite outgrowth in PC12 cells. Furthermore, specific inhibitors for the endoplasmic reticulum protein inositol 1,4,5-triphosphate (IP(3 receptors and several common signaling pathways (PLC-γ, PI3K, Akt, p38 MAPK, and c-Jun N-terminal kinase (JNK, and the Ras/Raf/ERK/MAPK significantly blocked the potentiation of NGF-induced neurite outgrowth by cilostazol. Using a proteomics analysis, we identified that levels of eukaryotic translation elongation factor eEF1A1 protein were significantly increased by treatment with cilostazol, but not cilostamide, in PC12 cells. Moreover, the potentiating effects of cilostazol on NGF-induced neurite outgrowth were significantly antagonized by treatment with eEF1A1 RNAi, but not the negative control of eEF1A1. These findings suggest that eEF1A1 and several common cellular signaling pathways might play a role in the mechanism of cilostazol-induced neurite outgrowth. Therefore, agents that can increase the eEF1A1 protein may have therapeutic relevance in diverse conditions with altered neurite outgrowth.

Cladding axial elongation models for FRAP-T6

International Nuclear Information System (INIS)

Shah, V.N.; Carlson, E.R.; Berna, G.A.

1983-01-01

This paper presents a description of the cladding axial elongation models developed at the Idaho National Engineering Laboratory (INEL) for use by the FRAP-T6 computer code in analyzing the response of fuel rods during reactor transients in light water reactors (LWR). The FRAP-T6 code contains models (FRACAS-II subcode) that analyze the structural response of a fuel rod including pellet-cladding-mechanical-interaction (PCMI). Recently, four models were incorporated into FRACAS-II to calculate cladding axial deformation: (a) axial PCMI, (b) trapped fuel stack, (c) fuel relocation, and (d) effective fuel thermal expansion. Comparisons of cladding axial elongation measurements from two experiments with the corresponding FRAP-T6 calculations are presented

Presence of non-O157 Shiga toxin-producing Escherichia coli, enterotoxigenic E. coli, enteropathogenic E. coli and Salmonella in fresh beetroot (Beta vulgaris L.) juice from public markets in Mexico.

Science.gov (United States)

Gómez-Aldapa, Carlos A; Rangel-Vargas, Esmeralda; Bautista-De León, Haydee; Castro-Rosas, Javier

2014-10-01

Unpasteurized juice has been associated with foodborne illness outbreaks for many years. Beetroot is a vegetable grown all over the world in temperate areas. In Mexico beetroot is consumed cooked in salads or raw as fresh unpasteurized juices. No data about the microbiological quality or safety of unpasteurized beetroot juices are available. Indicator bacteria, diarrheagenic Escherichia coli pathotypes (DEP) and Salmonella frequencies were determined for fresh unpasteurized beetroot juice from restaurants. One hundred unpasteurized beetroot juice samples were collected from public markets in Pachuca, Mexico. Frequencies in these samples were 100%, 75%, 53%, 9% and 4% of positive samples, for coliform bacteria, fecal coliforms, E. coli, DEP and Salmonella, respectively. Identified DEP included enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC) and non-O157 Shiga toxin-producing E. coli (STEC). Identified Salmonella serotypes included Typhimurium and Enteritidis. This is the first report of microbiological quality and atypical EPEC, ETEC, non-O157 STEC and Salmonella isolation from fresh raw beetroot juice in Mexico. Fresh raw beetroot juice from markets is very probably an important factor contributing to the endemicity of atypical EPEC, ETEC, non-O157 STEC and Salmonella-related gastroenteritis in Mexico. © 2014 Society of Chemical Industry.

Identification of genes important for growth of asymptomatic bacteriuria Escherichia coli in urine.

Science.gov (United States)

Vejborg, Rebecca M; de Evgrafov, Mari R; Phan, Minh Duy; Totsika, Makrina; Schembri, Mark A; Hancock, Viktoria

2012-09-01

Escherichia coli is the most important etiological agent of urinary tract infections (UTIs). Unlike uropathogenic E. coli, which causes symptomatic infections, asymptomatic bacteriuria (ABU) E. coli strains typically lack essential virulence factors and colonize the bladder in the absence of symptoms. While ABU E. coli can persist in the bladder for long periods of time, little is known about the genetic determinants required for its growth and fitness in urine. To identify such genes, we have employed a transposon mutagenesis approach using the prototypic ABU E. coli strain 83972 and the clinical ABU E. coli strain VR89. Six genes involved in the biosynthesis of various amino acids and nucleobases were identified (carB, argE, argC, purA, metE, and ilvC), and site-specific mutants were subsequently constructed in E. coli 83972 and E. coli VR89 for each of these genes. In all cases, these mutants exhibited reduced growth rates and final cell densities in human urine. The growth defects could be complemented in trans as well as by supplementation with the appropriate amino acid or nucleobase. When assessed in vivo in a mouse model, E. coli 83972carAB and 83972argC showed a significantly reduced competitive advantage in the bladder and/or kidney during coinoculation experiments with the parent strain, whereas 83972metE and 83972ilvC did not. Taken together, our data have identified several biosynthesis pathways as new important fitness factors associated with the growth of ABU E. coli in human urine.

E coli enteritis

Science.gov (United States)

... coli; Food poisoning - E. coli; E. coli diarrhea; Hamburger disease ... coleslaw or potato salad) that have been out of the refrigerator too ... reheated Fish or oysters Raw fruits or vegetables that have ...

Dendrosomatic Sonic Hedgehog Signaling in Hippocampal Neurons Regulates Axon Elongation

Science.gov (United States)

Petralia, Ronald S.; Ott, Carolyn; Wang, Ya-Xian; Lippincott-Schwartz, Jennifer; Mattson, Mark P.

2015-01-01

The presence of Sonic Hedgehog (Shh) and its signaling components in the neurons of the hippocampus raises a question about what role the Shh signaling pathway may play in these neurons. We show here that activation of the Shh signaling pathway stimulates axon elongation in rat hippocampal neurons. This Shh-induced effect depends on the pathway transducer Smoothened (Smo) and the transcription factor Gli1. The axon itself does not respond directly to Shh; instead, the Shh signal transduction originates from the somatodendritic region of the neurons and occurs in neurons with and without detectable primary cilia. Upon Shh stimulation, Smo localization to dendrites increases significantly. Shh pathway activation results in increased levels of profilin1 (Pfn1), an actin-binding protein. Mutations in Pfn1's actin-binding sites or reduction of Pfn1 eliminate the Shh-induced axon elongation. These findings indicate that Shh can regulate axon growth, which may be critical for development of hippocampal neurons. SIGNIFICANCE STATEMENT Although numerous signaling mechanisms have been identified that act directly on axons to regulate their outgrowth, it is not known whether signals transduced in dendrites may also affect axon outgrowth. We describe here a transcellular signaling pathway in embryonic hippocampal neurons in which activation of Sonic Hedgehog (Shh) receptors in dendrites stimulates axon growth. The pathway involves the dendritic-membrane-associated Shh signal transducer Smoothened (Smo) and the transcription factor Gli, which induces the expression of the gene encoding the actin-binding protein profilin 1. Our findings suggest scenarios in which stimulation of Shh in dendrites results in accelerated outgrowth of the axon, which therefore reaches its presumptive postsynaptic target cell more quickly. By this mechanism, Shh may play critical roles in the development of hippocampal neuronal circuits. PMID:26658865

Factors affecting expression of the recF gene of Escherichia coli K-12.

Science.gov (United States)

Sandler, S J; Clark, A J

1990-01-31

This report describes four factors which affect expression of the recF gene from strong upstream lambda promoters under temperature-sensitive cIAt2-encoded repressor control. The first factor was the long mRNA leader sequence consisting of the Escherichia coli dnaN gene and 95% of the dnaA gene and lambda bet, N (double amber) and 40% of the exo gene. When most of this DNA was deleted, RecF became detectable in maxicells. The second factor was the vector, pBEU28, a runaway replication plasmid. When we substituted pUC118 for pBEU28, RecF became detectable in whole cells by the Coomassie blue staining technique. The third factor was the efficiency of initiation of translation. We used site-directed mutagenesis to change the mRNA leader, ribosome-binding site and the 3 bp before and after the translational start codon. Monitoring the effect of these mutational changes by translational fusion to lacZ, we discovered that the efficiency of initiation of translation was increased 30-fold. Only an estimated two- or threefold increase in accumulated levels of RecF occurred, however. This led us to discover the fourth factor, namely sequences in the recF gene itself. These sequences reduce expression of the recF-lacZ fusion genes 100-fold. The sequences responsible for this decrease in expression occur in four regions in the N-terminal half of recF. Expression is reduced by some sequences at the transcriptional level and by others at the translational level.

Risk factors associated with faecal shedding of verocytotoxin-producing Escherichia coli O157 in eight known-infected Danish dairy herds

DEFF Research Database (Denmark)

Rugbjerg, Helene; Nielsen, Eva Møller; Andersen, Jens Strodl

2003-01-01

A risk-factor study was performed in eight dairy herds found to excrete verocytotoxin-producing Escherichia coli (VTEC) O157 in a former prevalence study. Associations between excretion of VTEC O157 and management factors such as housing and feeding were analysed in a generalised linear mixed mod...... days with the mother after calving. Calves aged 5-24 months that had been moved within the last 2 weeks had a higher risk, but risk was reduced if fed barley silage. Cows fed grain or molasses had a higher risk of excreting VTEC O157....

Segmentation of elongated structures in medical images

NARCIS (Netherlands)

Staal, Jozef Johannes

2004-01-01

The research described in this thesis concerns the automatic detection, recognition and segmentation of elongated structures in medical images. For this purpose techniques have been developed to detect subdimensional pointsets (e.g. ridges, edges) in images of arbitrary dimension. These

Treatment for bovine Escherichia coli mastitis - an evidence-based approach.

Science.gov (United States)

Suojala, L; Kaartinen, L; Pyörälä, S

2013-12-01

Bovine mastitis caused by Escherichia coli can range from being a subclinical infection of the mammary gland to a severe systemic disease. Cow-dependent factors such as lactation stage and age affect the severity of coliform mastitis. Evidence for the efficacy of antimicrobial treatment for E. coli mastitis is very limited. Antimicrobial resistance is generally not a limiting factor for treatment, but it should be monitored to detect changes in resistance profiles. The only antimicrobials for which there is some scientific evidence of beneficial effects in the treatment for E. coli mastitis are fluoroquinolones and cephalosporins. Both are critically important drugs, the use of which in animals destined for food should be limited to specific indications and should be based on bacteriological diagnosis. The suggested routine protocol in dairy herds could target the primary antimicrobial treatment for mastitis, specifically infections caused by gram-positive bacteria. In E. coli mastitis with mild to moderate clinical signs, a non-antimicrobial approach (anti-inflammatory treatment, frequent milking and fluid therapy) should be the first option. In cases of severe E. coli mastitis, parenteral administration of fluoroquinolones, or third- or fourth-generation cephalosporins, is recommended due to the risk of unlimited growth of bacteria in the mammary gland and ensuing bacteremia. Evidence for the efficacy of intramammary-administered antimicrobial treatment for E. coli mastitis is so limited that it cannot be recommended. Nonsteroidal anti-inflammatory drugs have documented the efficacy in the treatment for E. coli mastitis and are recommended for supportive treatment for clinical mastitis. © 2013 John Wiley & Sons Ltd.

Vascular Endothelial Growth Factor Receptor 1 Contributes to Escherichia coli K1 Invasion of Human Brain Microvascular Endothelial Cells through the Phosphatidylinositol 3-Kinase/Akt Signaling Pathway▿ †

OpenAIRE

Zhao, Wei-Dong; Liu, Wei; Fang, Wen-Gang; Kim, Kwang Sik; Chen, Yu-Hua

2010-01-01

Escherichia coli is the most common Gram-negative organism causing neonatal meningitis. Previous studies demonstrated that E. coli K1 invasion of brain microvascular endothelial cells (BMEC) is required for penetration into the central nervous system, but the microbe-host interactions that are involved in this process remain incompletely understood. Here we report the involvement of vascular endothelial growth factor receptor 1 (VEGFR1) expressed on human brain microvascular endothelial cells...

A study on elongation/contraction behavior and mechanical properties of oxy-polyacrylonitrile(PAN) fiber in basic/acidic solution for artificial muscle applications

Energy Technology Data Exchange (ETDEWEB)

Lee, Y.K.; Kim, S.W.; Lee, K.S.; Cho, I.H.; Lee, J.H.; Lee, J.W. [Sungkyunkwan University, Suwon (Korea); Kim, K.J. [University of Nevada, Reno (United States); Nam, J.D. [Sungkyunkwan University, Suwon (Korea)

2002-07-01

Oxy-PAN fiber prepared from the preoxidation and saponification of raw PAN fiber is known to elongate and contract when immersed in basic and acidic solutions, respectively. In this study, about 30% elongation in NaOH solution and 30{approx}50% contraction in HCl solution have been observed. In mechanical test, the mechanical properties of oxy-PAN fiber in the contracted state was stronger than that in the elongated state. These behaviors and mechanical properties are compared to those of living muscle and linear actuator. The change of length in NaOH and HCl solutions is due to switching between a hydrophilic and a hydrophobic structure. Other reasons are exchange of ion and water in/out of oxy-PAN fiber, and osmotic pressure difference associated with relevant ions. Much studies are needed to clarify the effective factors on but the oxy-PAN fiber's elongation/contraction behavior and mechanical properties, but the oxy-PAN fiber prepared in our laboratory has a sufficient potential for application as artificial muscle and linear actuator. (author). 20 refs., 1 tab., 9 figs.

Environmental Escherichia coli: Ecology and public health implications - A review

Science.gov (United States)

Jang, Jeonghwan; Hur, Hor-Gil; Sadowsky, Michael J.; Byappanahalli, Muruleedhara; Yan, Tao; Ishii, Satoshi

2017-01-01

Escherichia coli is classified as a rod-shaped, Gram-negative bacterium in the family Enterobacteriaceae. The bacterium mainly inhabits the lower intestinal tract of warm-blooded animals, including humans, and is often discharged into the environment through feces or wastewater effluent. The presence of E. coli in environmental waters has long been considered as an indicator of recent fecal pollution. However, numerous recent studies have reported that some specific strains of E. coli can survive for long periods of time, and potentially reproduce, in extra-intestinal environments. This indicates that E. coli can be integrated into indigenous microbial communities in the environment. This naturalization phenomenon calls into question the reliability of E. coli as a fecal indicator bacterium (FIB). Recently, many studies reported that E. coli populations in the environment are affected by ambient environmental conditions affecting their long-term survival. Large-scale studies of population genetics provide the diversity and complexity of E. coli strains in various environments, affected by multiple environmental factors. This review examines the current knowledge on the ecology of E. coli strains in various environments in regards to its role as a FIB and as a naturalized member of indigenous microbial communities. Special emphasis is given on the growth of pathogenic E. coli in the environment, and the population genetics of environmental members of the genus Escherichia. The impact of environmental E. coli on water quality and public health is also discussed.

The Drosophila mitochondrial translation elongation factor G1 contains a nuclear localization signal and inhibits growth and DPP signaling.

Directory of Open Access Journals (Sweden)

Catherine Trivigno

2011-02-01

Full Text Available Mutations in the human mitochondrial elongation factor G1 (EF-G1 are recessive lethal and cause death shortly after birth. We have isolated mutations in iconoclast (ico, which encodes the highly conserved Drosophila orthologue of EF-G1. We find that EF-G1 is essential during fly development, but its function is not required in every tissue. In contrast to null mutations, missense mutations exhibit stronger, possibly neomorphic phenotypes that lead to premature death during embryogenesis. Our experiments show that EF-G1 contains a secondary C-terminal nuclear localization signal. Expression of missense mutant forms of EF-G1 can accumulate in the nucleus and cause growth and patterning defects and animal lethality. We find that transgenes that encode mutant human EF-G1 proteins can rescue ico mutants, indicating that the underlying problem of the human disease is not just the loss of enzymatic activity. Our results are consistent with a model where EF-G1 acts as a retrograde signal from mitochondria to the nucleus to slow down cell proliferation if mitochondrial energy output is low.

Research of the influencing factors of the immobilized redox mediators accelerating Cr(Ⅵ reduction by Escherichia coli BL21

Directory of Open Access Journals (Sweden)

Jiapeng PING

2017-10-01

Full Text Available In order to study the influencing factors of non-dissolved redox mediators on Cr (Ⅵ bioreduction, the accelerating effect of non-dissolved redox mediators immobilized by cellulose acetate (CA on the reduction of Cr(Ⅵ by Escherichia coli BL21 is investigated. The results show that the accelerating order is 1-chloroanthraquinone>1,5-dichloroanthraquinone>2-chloroanthraquinone>1,8-dichloroanthraquinone>anthraquinone>1,4,5,8-tetrachloroanthtaquinone; the optimal concentration of 1-chloroanthraquinone pH and initial Cr(Ⅵ concentration are 0.048 mol/L, 7.00 and 30 mg/L, respectively; the removal rate increases with the increasing temperature when it is in the range of 20~60 ℃; after 6 times of recycling experiments, and the Cr(Ⅵ bioreduction rate with the immobilized 1-chloroanthraquinone maintains above 5 times of margin bacterium's. It indicates that non-dissolved redox mediators immobilized by CA can effectively accelerate the reduction rate of Cr(Ⅵ by Escherichia coli BL21, which has favourable application value.

Transcription profile of Escherichia coli: genomic SELEX search for regulatory targets of transcription factors.

Science.gov (United States)

Ishihama, Akira; Shimada, Tomohiro; Yamazaki, Yukiko

2016-03-18

Bacterial genomes are transcribed by DNA-dependent RNA polymerase (RNAP), which achieves gene selectivity through interaction with sigma factors that recognize promoters, and transcription factors (TFs) that control the activity and specificity of RNAP holoenzyme. To understand the molecular mechanisms of transcriptional regulation, the identification of regulatory targets is needed for all these factors. We then performed genomic SELEX screenings of targets under the control of each sigma factor and each TF. Here we describe the assembly of 156 SELEX patterns of a total of 116 TFs performed in the presence and absence of effector ligands. The results reveal several novel concepts: (i) each TF regulates more targets than hitherto recognized; (ii) each promoter is regulated by more TFs than hitherto recognized; and (iii) the binding sites of some TFs are located within operons and even inside open reading frames. The binding sites of a set of global regulators, including cAMP receptor protein, LeuO and Lrp, overlap with those of the silencer H-NS, suggesting that certain global regulators play an anti-silencing role. To facilitate sharing of these accumulated SELEX datasets with the research community, we compiled a database, 'Transcription Profile of Escherichia coli' (www.shigen.nig.ac.jp/ecoli/tec/). © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

A multi-level approach for investigating socio-economic and agricultural risk factors associated with rates of reported cases of Escherichia coli O157 in humans in Alberta, Canada.

Science.gov (United States)

Pearl, D L; Louie, M; Chui, L; Doré, K; Grimsrud, K M; Martin, S W; Michel, P; Svenson, L W; McEwen, S A

2009-10-01

Using negative binomial and multi-level Poisson models, the authors determined the statistical significance of agricultural and socio-economic risk factors for rates of reported disease associated with Escherichia coli O157 in census subdivisions (CSDs) in Alberta, Canada, 2000-2002. Variables relating to population stability, aboriginal composition of the CSDs, and the economic relationship between CSDs and urban centres were significant risk factors. The percentage of individuals living in low-income households was not a statistically significant risk factor for rates of disease. The statistical significance of cattle density, recorded at a higher geographical level, depended on the method used to correct for overdispersion, the number of levels included in the multi-level models, and the choice of using all reported cases or only sporadic cases. Our results highlight the importance of local socio-economic risk factors in determining rates of disease associated with E. coli O157, but their relationship with individual risk factors requires further evaluation.

Experimental and mathematical methods for representing relative surface elongation of the ACL

NARCIS (Netherlands)

Pioletti, D. P.; Heegaard, J. H.; Rakotomanana, R. L.; Leyvraz, P. F.; Blankevoort, L.

1995-01-01

The common approach to assess the stabilizing role of the ACL in the knee has been to measure the elongation of a few marked fibers in the ligament. A comparison of the relative elongation (RE) of these marked fibers between different specimens and studies is delicate due to the difficulty of

Phytotoxicity of veterinary antibiotics to seed germination and root elongation of crops.

Science.gov (United States)

Pan, Min; Chu, L M

2016-04-01

Large quantities of veterinary antibiotics (VAs) are being used worldwide in agricultural fields through wastewater irrigation and manure application. They cause damages to the ecosystem when discharged into the environment, but there is a lack of information on their toxicity to plants and animals. This study evaluated the phytotoxic effects of five major VAs, namely tetracycline (TC), sulfamethazine (SMZ), norfloxacin (NOR), erythromycin (ERY) and chloramphenicol (CAP), on seed germination and root elongation in lettuce, tomato, carrot and cucumber, and investigated the relationship between their physicochemical properties and phytotoxicities. Results show that these compounds significantly inhibited root elongation (ptest. TC was associated with the highest level of toxicity, followed by NOR, ERY, SMZ and CAP. Regarding crop species, lettuce was found to be sensitive to most of the VAs. The median effect concentration (EC50) of TC, SMZ, NOR, ERY and CAP to lettuce was 14.4, 157, 49.4, 68.8 and 204 mg/L, respectively. A quantitative structure-activity relationship (QSAR) model has been established based on the measured data. It is evident that hydrophobicity was the most important factor governing the phytotoxicity of these compounds to seeds, which could be explained by the polar narcosis mechanism. Lettuce is considered a good biomarker for VAs in the environment. According to the derived equation, phytotoxicities of selected VA compounds on different crops can be calculated, which could be applicable to other VAs. Environmental risks of VAs were summarized based on the phytotoxicity results and other persistent factors. Copyright © 2015 Elsevier Inc. All rights reserved.

An evolutionary analysis of genome expansion and pathogenicity in Escherichia coli.

Science.gov (United States)

Bohlin, Jon; Brynildsrud, Ola B; Sekse, Camilla; Snipen, Lars

2014-10-09

There are several studies describing loss of genes through reductive evolution in microbes, but how selective forces are associated with genome expansion due to horizontal gene transfer (HGT) has not received similar attention. The aim of this study was therefore to examine how selective pressures influence genome expansion in 53 fully sequenced and assembled Escherichia coli strains. We also explored potential connections between genome expansion and the attainment of virulence factors. This was performed using estimations of several genomic parameters such as AT content, genomic drift (measured using relative entropy), genome size and estimated HGT size, which were subsequently compared to analogous parameters computed from the core genome consisting of 1729 genes common to the 53 E. coli strains. Moreover, we analyzed how selective pressures (quantified using relative entropy and dN/dS), acting on the E. coli core genome, influenced lineage and phylogroup formation. Hierarchical clustering of dS and dN estimations from the E. coli core genome resulted in phylogenetic trees with topologies in agreement with known E. coli taxonomy and phylogroups. High values of dS, compared to dN, indicate that the E. coli core genome has been subjected to substantial purifying selection over time; significantly more than the non-core part of the genome (pcoli genome size correlated with estimated HGT size (pcoli are largely attained through HGT. No associations were found between selective pressures operating on the E. coli core genome, as estimated using relative entropy, and genome size (p~0.98). On a larger time frame, genome expansion in E. coli, which is significantly associated with the acquisition of virulence factors, appears to be independent of selective forces operating on the core genome.

Enhancing succinic acid biosynthesis in Escherichia coli by engineering its global transcription factor, catabolite repressor/activator (Cra).

Science.gov (United States)

Zhu, Li-Wen; Xia, Shi-Tao; Wei, Li-Na; Li, Hong-Mei; Yuan, Zhan-Peng; Tang, Ya-Jie

2016-11-04

This study was initiated to improve E. coli succinate production by engineering the E. coli global transcription factor, Cra (catabolite repressor/activator). Random mutagenesis libraries were generated through error-prone PCR of cra. After re-screening and mutation site integration, the best mutant strain was Tang1541, which provided a final succinate concentration of 79.8 ± 3.1 g/L: i.e., 22.8% greater than that obtained using an empty vector control. The genes and enzymes involved in phosphoenolpyruvate (PEP) carboxylation and the glyoxylate pathway were activated, either directly or indirectly, through the mutation of Cra. The parameters for interaction of Cra and DNA indicated that the Cra mutant was bound to aceBAK, thereby activating the genes involved in glyoxylate pathway and further improving succinate production even in the presence of its effector fructose-1,6-bisphosphate (FBP). It suggested that some of the negative effect of FBP on Cra might have been counteracted through the enhanced binding affinity of the Cra mutant for FBP or the change of Cra structure. This work provides useful information about understanding the transcriptional regulation of succinate biosynthesis.

E. Coli Infections

Science.gov (United States)

E. coli is the name of a type of bacteria that lives in your intestines. Most types of E. coli are harmless. However, some types can make you ... type causes travelers' diarrhea. The worst type of E. coli causes bloody diarrhea, and can sometimes cause kidney ...

Antimicrobial resistance patterns, clinical features, and risk factors for septic shock and death of nosocomial E coli bacteremia in adult patients with hematological disease: A monocenter retrospective study in China.

Science.gov (United States)

Ma, Jie; Li, Ning; Liu, Yajie; Wang, Chong; Liu, Xiaoyan; Chen, Shengmei; Xie, Xinsheng; Gan, Silin; Wang, Meng; Cao, Weijie; Wang, Fang; Liu, Yanfan; Wan, Dingming; Sun, Ling; Sun, Hui

2017-05-01

The aim of this retrospective analysis was to evaluate the antimicrobial resistance, clinical features, and risk factors for septic shock and death of nosocomial E coli bacteremia in adult patients in a single hematological center in China. A retrospective case-control study of 157 adult hematological patients with 168 episodes of E coli bacteremia was initiated from April 2012 to July 2015. Antimicrobial susceptibility as well as antimicrobial co-resistance rates were analyzed. Clinical features and outcomes were also studied. In addition, risk factors for septic shock and death were investigated. Among the 553 positive blood isolates during the study period, the prevalence of E coli was 33.3% and ESBL production strains represented 61.9% of those examined. In all the E coli strains isolated, 85.6% were multidrug-resistance (MDR), 2.4% were extensive drug resistance (XDR), and 6.0% were resistant to carbapenems. More MDR phenotype was noted in ESBL-EC strains (98.6% vs 62.8%, PE coli (94.0% and 92.0%, respectively), but lower co-resistance rates to other antibiotics. Carbapenem resistant strains retained full sensitivity to tigecycline and 60% to amikacin. Piperacillin/tazobatam was the third sensitive drug to both ESBL-EC (77.1%) and non-ESBL-EC (86.0%). In our series, 81.6% episodes received appropriate initial antibiotic treatment and no significant decrease in it was found in bacteremia due to ESBL E coli and patients with neutropenia, septic shock. Septic shock was noted in 15.5% patients and the overall 30-day mortality rate was 21.7%. Multivariate analysis revealed that induction chemotherapy (OR 2.126; 95% CI 1.624-11.332; P = .003) and polymicrobial infection (OR 3.628; 95% CI 1.065-21.219; P = .041) were risk factors for septic shock, whereas male (OR 2.223; 95% CI 1.132-12.022; P E coli bacteremia which is still a major life-threatening problem, especially for patients with septic shock. For empirical antimicrobial therapy, combination based on

Environmental Escherichia coli: ecology and public health implications-a review.

Science.gov (United States)

Jang, J; Hur, H-G; Sadowsky, M J; Byappanahalli, M N; Yan, T; Ishii, S

2017-09-01

Escherichia coli is classified as a rod-shaped, Gram-negative bacterium in the family Enterobacteriaceae. The bacterium mainly inhabits the lower intestinal tract of warm-blooded animals, including humans, and is often discharged into the environment through faeces or wastewater effluent. The presence of E. coli in environmental waters has long been considered as an indicator of recent faecal pollution. However, numerous recent studies have reported that some specific strains of E. coli can survive for long periods of time, and potentially reproduce, in extraintestinal environments. This indicates that E. coli can be integrated into indigenous microbial communities in the environment. This naturalization phenomenon calls into question the reliability of E. coli as a faecal indicator bacterium (FIB). Recently, many studies reported that E. coli populations in the environment are affected by ambient environmental conditions affecting their long-term survival. Large-scale studies of population genetics revealed the diversity and complexity of E. coli strains in various environments, which are affected by multiple environmental factors. This review examines the current knowledge on the ecology of E. coli strains in various environments with regard to its role as a FIB and as a naturalized member of indigenous microbial communities. Special emphasis is given on the growth of pathogenic E. coli in the environment, and the population genetics of environmental members of the genus Escherichia. The impact of environmental E. coli on water quality and public health is also discussed. © 2017 The Society for Applied Microbiology.

Glycan-functionalized diamond nanoparticles as potent E. coli anti-adhesives

Science.gov (United States)

Barras, Alexandre; Martin, Fernando Ariel; Bande, Omprakash; Baumann, Jean-Sébastien; Ghigo, Jean-Marc; Boukherroub, Rabah; Beloin, Christophe; Siriwardena, Aloysius; Szunerits, Sabine

2013-02-01

Bacterial attachment and subsequent biofilm formation on biotic surfaces or medical devices is an increasing source of infections in clinical settings. A large proportion of these biofilm-related infections are caused by Escherichia coli, a major nosocomial pathogen, in which the major adhesion factor is the FimH adhesin located at the tip of type 1 fimbriae. Inhibition of FimH-mediated adhesion has been identified as an efficient antibiotic-alternative strategy to potentially reduce E. coli-related infections. In this article we demonstrate that nanodiamond particles, covently modified with mannose moieties by a ``click'' chemistry approach, are able to efficiently inhibit E. coli type 1 fimbriae-mediated adhesion to eukaryotic cells with relative inhibitory potency (RIP) of as high as 9259 (bladder cell adhesion assay), which is unprecedented when compared with RIP values previously reported for alternate multivalent mannose-functionalized nanostructures designed to inhibit E. coli adhesion. Also remarkable is that these novel mannose-modified NDs reduce E. coli biofilm formation, a property previously not observed for multivalent glyco-nanoparticles and rarely demonstrated for other multivalent or monovalent mannose glycans. This work sets the stage for the further evaluation of these novel NDs as an anti-adhesive therapeutic strategy against E. coli-derived infections.Bacterial attachment and subsequent biofilm formation on biotic surfaces or medical devices is an increasing source of infections in clinical settings. A large proportion of these biofilm-related infections are caused by Escherichia coli, a major nosocomial pathogen, in which the major adhesion factor is the FimH adhesin located at the tip of type 1 fimbriae. Inhibition of FimH-mediated adhesion has been identified as an efficient antibiotic-alternative strategy to potentially reduce E. coli-related infections. In this article we demonstrate that nanodiamond particles, covently modified with

Phytosterol content and the campesterol:sitosterol ratio influence cotton fiber development: role of phytosterols in cell elongation.

Science.gov (United States)

Deng, Shasha; Wei, Ting; Tan, Kunling; Hu, Mingyu; Li, Fang; Zhai, Yunlan; Ye, Shue; Xiao, Yuehua; Hou, Lei; Pei, Yan; Luo, Ming

2016-02-01

Phytosterols play an important role in plant growth and development, including cell division, cell elongation, embryogenesis, cellulose biosynthesis, and cell wall formation. Cotton fiber, which undergoes synchronous cell elongation and a large amount of cellulose synthesis, is an ideal model for the study of plant cell elongation and cell wall biogenesis. The role of phytosterols in fiber growth was investigated by treating the fibers with tridemorph, a sterol biosynthetic inhibitor. The inhibition of phytosterol biosynthesis resulted in an apparent suppression of fiber elongation in vitro or in planta. The determination of phytosterol quantity indicated that sitosterol and campesterol were the major phytosterols in cotton fibers; moreover, higher concentrations of these phytosterols were observed during the period of rapid elongation of fibers. Furthermore, the decrease and increase in campesterol:sitosterol ratio was associated with the increase and decease in speed of elongation, respectively, during the elongation stage. The increase in the ratio was associated with the transition from cell elongation to secondary cell wall synthesis. In addition, a number of phytosterol biosynthetic genes were down-regulated in the short fibers of ligon lintless-1 mutant, compared to its near-isogenic wild-type TM-1. These results demonstrated that phytosterols play a crucial role in cotton fiber development, and particularly in fiber elongation.

THE WIDESPREAD OCCURRENCE OF THE ENTEROHEMOLYSIN GENE EHLYA AMONG ENVIRONMENTAL STRAINS OF ESCHERICHIA COLI

Science.gov (United States)

The putative virulence factor enterohemolysin, encoded for by the ehlyA gene, has been closely associated with the pathogenic enterohemorrhagic Escherichia coli (EHEC) group. E. coli isolates from effluents from seven geographically dispersed municipal ...

An Actomyosin-Arf-GEF Negative Feedback Loop for Tissue Elongation under Stress.

Science.gov (United States)

West, Junior J; Zulueta-Coarasa, Teresa; Maier, Janna A; Lee, Donghoon M; Bruce, Ashley E E; Fernandez-Gonzalez, Rodrigo; Harris, Tony J C

2017-08-07

In response to a pulling force, a material can elongate, hold fast, or fracture. During animal development, multi-cellular contraction of one region often stretches neighboring tissue. Such local contraction occurs by induced actomyosin activity, but molecular mechanisms are unknown for regulating the physical properties of connected tissue for elongation under stress. We show that cytohesins, and their Arf small G protein guanine nucleotide exchange activity, are required for tissues to elongate under stress during both Drosophila dorsal closure (DC) and zebrafish epiboly. In Drosophila, protein localization, laser ablation, and genetic interaction studies indicate that the cytohesin Steppke reduces tissue tension by inhibiting actomyosin activity at adherens junctions. Without Steppke, embryogenesis fails, with epidermal distortions and tears resulting from myosin misregulation. Remarkably, actomyosin network assembly is necessary and sufficient for local Steppke accumulation, where live imaging shows Steppke recruitment within minutes. This rapid negative feedback loop provides a molecular mechanism for attenuating the main tension generator of animal tissues. Such attenuation relaxes tissues and allows orderly elongation under stress. Copyright © 2017 Elsevier Ltd. All rights reserved.

E. Coli

Science.gov (United States)

... for the bacteria's medical name Escherichia coli . The strange thing about these bacteria — and lots of other ... In some cases, E. coli poisoning can cause life-threatening kidney problems. What Can Kids Do? Adults ...

Quantitative Brightness Analysis of Fluorescence Intensity Fluctuations in E. Coli.

Directory of Open Access Journals (Sweden)

Kwang-Ho Hur

Full Text Available The brightness measured by fluorescence fluctuation spectroscopy specifies the average stoichiometry of a labeled protein in a sample. Here we extended brightness analysis, which has been mainly applied in eukaryotic cells, to prokaryotic cells with E. coli serving as a model system. The small size of the E. coli cell introduces unique challenges for applying brightness analysis that are addressed in this work. Photobleaching leads to a depletion of fluorophores and a reduction of the brightness of protein complexes. In addition, the E. coli cell and the point spread function of the instrument only partially overlap, which influences intensity fluctuations. To address these challenges we developed MSQ analysis, which is based on the mean Q-value of segmented photon count data, and combined it with the analysis of axial scans through the E. coli cell. The MSQ method recovers brightness, concentration, and diffusion time of soluble proteins in E. coli. We applied MSQ to measure the brightness of EGFP in E. coli and compared it to solution measurements. We further used MSQ analysis to determine the oligomeric state of nuclear transport factor 2 labeled with EGFP expressed in E. coli cells. The results obtained demonstrate the feasibility of quantifying the stoichiometry of proteins by brightness analysis in a prokaryotic cell.

Active feedback stabilization of axisymmetric modes in highly elongated tokamak plasmas

International Nuclear Information System (INIS)

Ward, D.J.; Hofmann, F.

1993-07-01

Active feedback stabilization of the vertical instability is studied for highly elongated tokamak plasmas (1≤κ≤3), and evaluated in particular for the TCV configuration. It is shown that the feedback can strongly affect the form of the eigenfunction for these highly elongated equilibria, and this can have detrimental effects on the ability of the feedback system to properly detect and stabilize the plasma. A calculation of the vertical displacement that uses poloidal flux measurements, poloidal magnetic field measurements, and corrections for the vessel eddy currents and active feedback currents was found to be effective even in the cases with the worst deformations of the eigenfunction. We also examine how these deformations affect differently shaped equilibria, and it is seen that the magnitude of the deformation of the eigenfunction is strongly function of the plasma elongation. (author) 15 figs., 13 refs

Functional, electrophysiological recoveries of rats with sciatic nerve lesions following transplantation of elongated DRG cells.

Science.gov (United States)

Dayawansa, Samantha; Zhang, Jun; Shih, Chung-Hsuan; Tharakan, Binu; Huang, Jason H

2016-04-01

Functional data are essential when confirming the efficacy of elongated dorsal root ganglia (DRG) cells as a substitute for autografting. We present the quantitative functional motor, electrophysiological findings of engineered DRG recipients for the first time. Elongated DRG neurons and autografts were transplanted to bridge 1-cm sciatic nerve lesions of Sprague Dawley (SD) rats. Motor recoveries of elongated DRG recipients (n=9), autograft recipients (n=9), unrepaired rats (n=9) and intact rats (n=6) were investigated using the angle board challenge test following 16 weeks of recovery. Electrophysiology studies were conducted to assess the functional recovery at 16 weeks. In addition, elongated DRGs were subjected to histology assessments. At threshold levels (35° angle) of the angle board challenge test, the autograft recipients', DRG recipients' and unrepaired group's performances were equal to each other and were less than the intact group (pDRG recipients' performance was similar to both the intact group and the autograft nerve recipients, and was better (pDRG constructs had intact signal transmission when recorded over the lesion, while the unrepaired rats did not. It was observed that elongated DRG neurons closely resembled an autograft during histological assessments. Performances of autograft and elongated DRG construct recipients were similar. Elongated DRG neurons should be further investigated as a substitute for autografting.

Overexpression of rice LRK1 restricts internode elongation by down-regulating OsKO2.

Science.gov (United States)

Yang, Mengfei; Qi, Weiwei; Sun, Fan; Zha, Xiaojun; Chen, Mingluan; Huang, Yunqing; Feng, Yu-Qi; Yang, Jinshui; Luo, Xiaojin

2013-01-01

Rice (Oryza sativa) has the potential to undergo rapid internodal elongation which determines plant height. Gibberellin is involved in internode elongation. Leucine-rich repeat receptor-like kinases (LRR-RLKs) are the largest subfamily of transmembrane receptor-like kinases in plants. LRR-RLKs play important functions in mediating a variety of cellular processes and regulating responses to environmental signals. LRK1, a PSK receptor homolog, is a member of the LRR-RLK family. In the present study, differences in ectopic expression of LRK1 were consistent with extent of rice internode elongation. Analyses of gene expression demonstrated that LRK1 restricts gibberellin biosynthesis during the internode elongation process by down-regulation of the gibberellin biosynthetic gene coding for ent-kaurene oxidase.

The interacting Cra and KdpE regulators are involved in the expression of multiple virulence factors in enterohemorrhagic Escherichia coli.

Science.gov (United States)

Njoroge, Jacqueline W; Gruber, Charley; Sperandio, Vanessa

2013-06-01

The human pathogen enterohemorrhagic Escherichia coli (EHEC) O157:H7 codes for two interacting DNA binding proteins, Cra and KdpE, that coregulate expression of the locus of enterocyte effacement (LEE) genes in a metabolite-dependent manner. Cra is a transcription factor that uses fluctuations in the concentration of carbon metabolism intermediates to positively regulate virulence of EHEC. KdpE is a response regulator that activates the transcription of homeostasis genes in response to salt-induced osmolarity and virulence genes in response to changes in metabolite concentrations. Here, we probed the transcriptional profiles of the Δcra, ΔkdpE, and Δcra ΔkdpE mutant strains and show that Cra and KdpE share several targets besides the LEE, but both Cra and KdpE also have independent targets. Several genes within O-islands (genomic islands present in EHEC but absent from E. coli K-12), such as Z0639, Z0640, Z3388, Z4267, and espFu (encoding an effector necessary for formation of attaching and effacing lesions on epithelial cells), were directly regulated by both Cra and KdpE, while Z2077 was only regulated by Cra. These studies identified and confirmed new direct targets for Cra and KdpE that included putative virulence factors as well as characterized virulence factors, such as EspFu and EspG. These results map out the role of the two interacting regulators, Cra and KdpE, in EHEC pathogenesis and global gene regulation.

Dean vortex membrane microfiltration and diafiltration of rBDNF E. coli inclusion bodies

NARCIS (Netherlands)

Schutyser, M.A.I.; Rupp, R.; Wideman, J.; Belfort, G.

2002-01-01

Cross-flow microfiltration (CMF) and diafiltration were used to concentrate and purify recombinant Brain-Derived Neutrophic Factor (rBDNF) inclusion bodies from an E. coli cell suspension and a homogenized E. coli cell suspension (homogenate/lysate). Although these processes have been tested

Enhancement of innate immune system in monocot rice by transferring the dicotyledonous elongation factor Tu receptor EFR

Institute of Scientific and Technical Information of China (English)

Fen Lu; Huiqin Wang; Shanzhi Wang; Wendi Jiang; Changlin Shan; Bin Li; Jun Yang; Shiyong Zhang; Wenxian Sun

2015-01-01

The elongation factor Tu (EF-Tu) receptor (EFR) in cruciferous plants specifical y recognizes the N-terminal acetylated elf18 region of bacterial EF-Tu and thereby activates plant immunity. It has been demonstrated that Arabidopsis EFR confers broad-spectrum bacterial resistance in the EFR transgenic solanaceous plants. Here, the transgenic rice plants (Oryza sativa L. ssp. japonica cv. Zhonghua 17) and cel cultures with constitutive expression of AtEFR were developed to investigate whether AtEFR senses EF-Tu and thus enhances bacterial resistance in the monocot plants. We demonstrated that the Xanthomonas oryzae-derived elf18 peptide induced oxidative burst and mitogen-activated protein kinase activa-tion in the AtEFR transgenic rice cel s and plants, respectively. Pathogenesis-related genes, such as OsPBZ1, were upregulated dramatical y in transgenic rice plant and cel lines in response to elf18 stimulation. Importantly, pretreatment with elf18 trig-gered strong resistance to X. oryzae pv. oryzae in the transgenic plants, which was largely dependent on the AtEFR expression level. These plants also exhibited enhanced resistance to rice bacterial brown stripe, but not to rice fungal blast. Col ectively, the results indicate that the rice plants with heterologous expression of AtEFR recognize bacterial EF-Tu and exhibit enhanced broad-spectrum bacterial disease resistance and that pattern recognition receptor-mediated immunity may be manipulated across the two plant classes, dicots and monocots.

Decoding the biosynthesis and function of diphthamide, an enigmatic modification of translation elongation factor 2 (EF2

Directory of Open Access Journals (Sweden)

Raffael Schaffrath

2014-05-01

Full Text Available Diphthamide is a highly conserved modification of archaeal and eukaryal translation elongation factor 2 (EF2 and yet why cells need EF2 to contain diphthamide is unclear. In yeast, the first steps of diphthamide synthesis and the genes (DPH1-DPH5 required to form the intermediate diphthine are well-documented. However, the last step, amidadation of diphthine to diphthamide, had largely been ill-defined. Remarkably, through mining genome-wide synthetic gene array (SGA and chemical genomics databases, recent studies by Uthman et al. [PLoS Genetics (2013 9, e1003334] and Su et al. [Proc. Natl. Acad. Sci. USA (2012 109, 19983-19987] have identified two more diphthamide players, DPH6 and DPH7. Consistent with roles in the amidation step, dph6 and dph7 deletion strains fail to complete diphthamide synthesis and accumulate diphthine-modified EF2. In contrast to Dph6, the catalytically relevant amidase, Dph7 appears to be regulatory. As shown by Uthman et al., it promotes dissociation of diphthine synthase (Dph5 from EF2, allowing diphthine amidation by Dph6 to occur and thereby coupling diphthine synthesis to the terminal step in the pathway. Remarkably, the study by Uthman et al. suggests that Dph5 has a novel role as an EF2 inhibitor that affects cell growth when diphthamide synthesis is blocked or incomplete and, importantly, shows that diphthamide promotes the accuracy of EF2 performance during translation.

1,8-cineole inhibits both proliferation and elongation of BY-2 cultured tobacco cells.

Science.gov (United States)

Yoshimura, Hiroko; Sawai, Yu; Tamotsu, Satoshi; Sakai, Atsushi

2011-03-01

Volatile monoterpenes such as 1,8-cineole inhibit the growth of Brassica campestris seedlings in a dose-dependent manner, and the growth-inhibitory effects are more severe for roots than hypocotyls. The preferential inhibition of root growth may be explained if the compounds inhibit cell proliferation more severely than cell elongation because root growth requires both elongation and proliferation of the constituent cells, whereas hypocotyl growth depends exclusively on elongation of existing cells. In order to examine this possibility, BY-2 suspension-cultured tobacco (Nicotiana tabacum) cells were treated with 1,8-cineole, and the inhibitory effects on cell proliferation and on cell elongation were assessed quantitatively. Treatment with 1,8-cineole lowered both the mitotic index and elongation of the cells in a dose-dependent manner, and the half-maximal inhibitory concentration (IC₅₀) for cell elongation was lower than that for cell proliferation. Moreover, 1,8-cineole also inhibited starch synthesis, with IC₅₀ lower than that for cell proliferation. Thus, the inhibitory effects of 1,8-cineole were not specific to cell proliferation; rather, 1,8-cineole seemed inhibitory to a variety of physiological activities when it was in direct contact with target cells. Based on these results, possible mechanisms for the mode of action of 1,8-cineole and for its preferential inhibition on root growth are discussed.

Contribution of Cell Elongation to the Biofilm Formation of Pseudomonas aeruginosa during Anaerobic Respiration

Science.gov (United States)

Park, Yongjin; Yoon, Sang Sun

2011-01-01

Pseudomonas aeruginosa, a gram-negative bacterium of clinical importance, forms more robust biofilm during anaerobic respiration, a mode of growth presumed to occur in abnormally thickened mucus layer lining the cystic fibrosis (CF) patient airway. However, molecular basis behind this anaerobiosis-triggered robust biofilm formation is not clearly defined yet. Here, we identified a morphological change naturally accompanied by anaerobic respiration in P. aeruginosa and investigated its effect on the biofilm formation in vitro. A standard laboratory strain, PAO1 was highly elongated during anaerobic respiration compared with bacteria grown aerobically. Microscopic analysis demonstrated that cell elongation likely occurred as a consequence of defective cell division. Cell elongation was dependent on the presence of nitrite reductase (NIR) that reduces nitrite (NO2 −) to nitric oxide (NO) and was repressed in PAO1 in the presence of carboxy-PTIO, a NO antagonist, demonstrating that cell elongation involves a process to respond to NO, a spontaneous byproduct of the anaerobic respiration. Importantly, the non-elongated NIR-deficient mutant failed to form biofilm, while a mutant of nitrate reductase (NAR) and wild type PAO1, both of which were highly elongated, formed robust biofilm. Taken together, our data reveal a role of previously undescribed cell biological event in P. aeruginosa biofilm formation and suggest NIR as a key player involved in such process. PMID:21267455

Interaction of sigma factor sigmaN with Escherichia coli RNA polymerase core enzyme.

Science.gov (United States)

Scott, D J; Ferguson, A L; Gallegos, M T; Pitt, M; Buck, M; Hoggett, J G

2000-12-01

The equilibrium binding and kinetics of assembly of the DNA-dependent RNA polymerase (RNAP) sigma(N)-holoenzyme has been investigated using biosynthetically labelled 7-azatryptophyl- (7AW)sigma(N). The spectroscopic properties of such 7AW proteins allows their absorbance and fluorescence to be monitored selectively, even in the presence of high concentrations of other tryptophan-containing proteins. The 7AWsigma(N) retained its biological activity in stimulating transcription from sigma(N)-specific promoters, and in in vitro gel electrophoresis assays of binding to core RNAP from Escherichia coli. Furthermore, five Trp-->Ala single mutants of sigma(N) were shown to support growth under conditions of nitrogen limitation, and showed comparable efficiency in activating the sigma(N)-dependent nifH promoter in vivo, indicating that none of the tryptophan residues were essential for activity. The equilibrium binding of 7AWsigma(N) to core RNAP was examined by analytical ultracentrifugation. In sedimentation equilibrium experiments, absorbance data at 315 nm (which reports selectively on the distribution of free and bound 7AWsigma(N)) established that a 1:1 complex was formed, with a dissociation constant lower than 2 microM. The kinetics of the interaction between 7AWsigma(N) and core RNAP was investigated using stopped-flow spectrofluorimetry. A biphasic decrease in fluorescence intensity was observed when samples were excited at 280 nm, whereas only the slower of the two phases was observed at 315 nm. The kinetic data were analysed in terms of a mechanism in which a fast bimolecular association of sigma(N) with core RNAP is followed by a relatively slow isomerization step. The consequences of these findings on the competition between sigma(N) and the major sigma factor, sigma(70), in Escherichia coli are discussed.

Chromosomal features of Escherichia coli serotype O2:K2, an avian pathogenic E. coli

DEFF Research Database (Denmark)

Jørgensen, Steffen L; Kudirkiene, Egle; Li, Lili

2017-01-01

Escherichia coli causing infection outside the gastrointestinal system are referred to as extra-intestinal pathogenic E. coli. Avian pathogenic E. coli is a subgroup of extra-intestinal pathogenic E. coli and infections due to avian pathogenic E. coli have major impact on poultry production econo...

Modeling cell elongation during germ band retraction: cell autonomy versus applied anisotropic stress

International Nuclear Information System (INIS)

Lynch, Holley E; Shane Hutson, M; Veldhuis, Jim; Wayne Brodland, G

2014-01-01

The morphogenetic process of germ band retraction in Drosophila embryos involves coordinated movements of two epithelial tissues—germ band and amnioserosa. The germ band shortens along its rostral–caudal or head-to-tail axis, widens along its perpendicular dorsal-ventral axis, and uncurls from an initial ‘U’ shape. The amnioserosa mechanically assists this process by pulling on the crook of the U-shaped germ band. The amnioserosa may also provide biochemical signals that drive germ band cells to change shape in a mechanically autonomous fashion. Here, we use a finite-element model to investigate how these two contributions reshape the germ band. We do so by modeling the response to laser-induced wounds in each of the germ band’s spatially distinct segments (T1–T3, A1–A9) during the middle of retraction when segments T1–A3 form the ventral arm of the ‘U’, A4–A7 form its crook, and A8–A9 complete the dorsal arm. We explore these responses under a range of externally applied stresses and internal anisotropy of cell edge tensions—akin to a planar cell polarity that can drive elongation of cells in a direction parallel to the minimum edge tension—and identify regions of parameter space (edge-tension anisotropy versus stress anisotropy) that best match previous experiments for each germ band segment. All but three germ band segments are best fit when the applied stress anisotropy and the edge-tension anisotropy work against one another—i.e., when the isolated effects would elongate cells in perpendicular directions. Segments in the crook of the germ band (A4–A7) have cells that elongate in the direction of maximum external stress, i.e., external stress anisotropy is dominant. In most other segments, the dominant factor is internal edge-tension anisotropy. These results are consistent with models in which the amnioserosa pulls on the crook of the germ band to mechanically assist retraction. In addition, they suggest a mechanical cue for

Significant enhancement by biochar of caproate production via chain elongation.

Science.gov (United States)

Liu, Yuhao; He, Pinjing; Shao, Liming; Zhang, Hua; Lü, Fan

2017-08-01

In this study, biochar was introduced into a chain elongation system to enhance the bioproduction of caproate and caprylate. The concentration of caproate increased to 21.1 g/L upon the addition of biochar, which is the highest level of caproate reported for such a system to date when ethanol was used as electron donor. The addition of biochar created a tougher system with more stable microorganism community structure for chain elongation, in which no obvious inhibition by products or substrates was observed, moreover, the lag phase was reduced 2.3-fold compared to the system without biochar. These reinforcement effect of biochar are attributed to the enhanced conductivity due to the significant enrichment of functional microorganisms via the microbial network surrounding smaller biochar particles, and via the adsorption on the rough surfaces or pores of larger particles, which facilitated electron transfer. Higher amounts of extracellular polymer substances and higher conductivity induced by biochar could contribute to the reinforcement effect in chain elongation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of benzyladenine (BA on auxin-induced stem elongation and thickening in tulip (Tulipa gesneriana L.

Directory of Open Access Journals (Sweden)

Marian Saniewski

2016-03-01

Full Text Available It is well known that stem elongation in tulip is induced by the auxin produced in the leaves and gynoecium. Excision of the flower bud and all the leaves in an early stage of tulip growth resulted in almost total inhibition of stem growth, but the inhibition was completely recovered by the exogenous application of auxin to the place from which the flower bud had been removed. Hormonal control of stem thickening in tulip is much less known. Additional application of benzyladenine (BA to the tulip stem by soaking a cotton wick wrapped around all the internodes only slightly inhibited stem growth induced by IAA at a concentration of 0.1 and 2.0%, but substantially stimulated the thickening of all the internodes. The treatment of the tulip stem with benzyladenine enabled direct contact of the cytokinin with the epidermis, which is an important factor in stem elongation. The experiment conducted in field conditions also showed that BA only slightly inhibited the elongation of the fourth internode induced by IAA, but stimulated the thickening of that internode. IAA applied at a concentration of 2.0% stimulated ethylene production to a much higher extent than IAA at a concentration of 0.1%, and BA affected the auxin-induced ethylene production only to a small extent. Metabolic significance of these findings is discussed.

Interplay between DNA supercoiling and transcription elongation.

Science.gov (United States)

Ma, Jie; Wang, Michelle

2014-01-01

Transcription-coupled DNA supercoiling has been shown to be an important regulator of transcription that is broadly present in the cell. Here we review experimental work which shows that RNA polymerase is a powerful torsional motor that can alter DNA topology and structure, and DNA supercoiling in turn directly affects transcription elongation.

Transcription elongation. Heterogeneous tracking of RNA polymerase and its biological implications.

Science.gov (United States)

Imashimizu, Masahiko; Shimamoto, Nobuo; Oshima, Taku; Kashlev, Mikhail

2014-01-01

Regulation of transcription elongation via pausing of RNA polymerase has multiple physiological roles. The pausing mechanism depends on the sequence heterogeneity of the DNA being transcribed, as well as on certain interactions of polymerase with specific DNA sequences. In order to describe the mechanism of regulation, we introduce the concept of heterogeneity into the previously proposed alternative models of elongation, power stroke and Brownian ratchet. We also discuss molecular origins and physiological significances of the heterogeneity.

Distribution of Escherichia Coli as Soil Pollutant around Antang Landfills

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Artiningsih, Andi; Zubair, Hazairin; Imran, A. M.; Widodo, Sri

2018-03-01

Tamangapa Antang Landfill locates around the residential area and faces an air and water pollution due to an open dumping system in its operation. The system arises a potential pollution in air, water and soil. Sampling was done surround the landfill in two parts, parallel and perpendicular to the ground water flow. This study shows the abundance of E. coli bacteria in soil around the Antang Landfills at depth of 10 to 20 cm (93x105 cfu/gr of soil) in the direction of groundwater flow. While in other locations the E. coli bacteria is not detected. The abundance of E. coli bacteria is a conjunction factor from landfill and human activities surround the area. The absence of E. coli bacteria in other location highly interpreted that the landfill is the major contributor of pollutant.

Urinary tract infections of Escherichia coli strains of chaperone-usher system.

Science.gov (United States)

Zalewska-Piatek, Beata M

2011-01-01

Urinary tract infections are a very serious health and economic problem affecting millions of people each year worldwide. The most common etiologic agent of this type of bacterial infections, involving the upper and lower urinary tract, are E. coli strains representing approximately 80% of cases. Uropathogenic E. coli strains produce several urovirulence factors which can be divided into two main types, surface virulence factors and exported virulence factors. Surface-exposed structures include mainly extracellular adhesive organelles such as fimbriae/pili necessary in adhesion, invasion, biofilm formation and cytokine induction. Among the surface-exposed polymeric adhesive structures there are three most invasive groups, type 1 pili, type P pili and Dr family of adhesins which are bioassembled via the conserved, among Gram-negative bacteria, chaperone-usher secretion system. Type 1 and P-piliated E. coli cause cystitis and pyelonephritis. The Dr family of adhesins recognizing DAF receptor is responsible for cystitis, pyelonephritis (especially in pregnant women) and diarrhoea (in infants). In addition, Dr-positive E. coli strains carry the risk of recurrent urinary tract infections. Pyelonephritis in pregnant women leads to a series of complications such as bacteremia, urosepsis, acute respiratory distress syndrome and even death. In the era of increasing drug resistance of bacteria, the development of vaccines, drugs termed pilicides and inhibitors of adhesion may be a promising tool in the fight against urogenital infections.

Incidence of Escherichia coli  - Glucuronidase Positive on Goat Milk

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Zorica Voşgan

2016-11-01

Full Text Available Papers on beta- glucuronidase sensitivity and specificity for identifying Escherichia coli in sources of environment, food, water, etc. have been published since 1976. In this study we conducted a review of the incidence of E. coli β- glucuronidase -positive in goat milk, obtained by hand milking throughout the lactation: spring, summer, autumn. The presence of E. coli in milk is considered both as a health indicator and a pathogenic factor capable of causing food poisoning. The determination of the E. coli β-glucuronidase-positive was carried using TBX medium by cultivating colonies typical blue at 440C. The absence of E. coli in milk yielded during the spring, when the animal milking is done three times a day, was found in the performed analyses; the same was observed during fall, when the milk production is lower and the milking is done once a day. The load of E. coli β-glucuronidase-positive was averaging 66.67 CFU/ml of goat milk, during the middle lactation period (July-August, in conditions of higher temperature. During this period, milking is done in the mountain zone, where the transhumance of animals takes place in summer. The presence of the species E. coli was also confirmed by microscopic examination. Attention should be paid to hygiene and milk should be immediately cooled, during hot weather, as E. coli can be a source of food poisoning.

On-farm starling populations and other environmental and management factors associated with the presence of cefotaxime and ciprofloxacin resistant E. coli among dairy cattle in Ohio.

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Medhanie, Genet A; Pearl, David L; McEwen, Scott A; Guerin, Michele T; Jardine, Claire M; Schrock, Jennifer; LeJeune, Jeffrey T

2016-11-01

Wild birds that forage around livestock facilities have been implicated as vectors of antimicrobial resistant organisms. Although antimicrobial resistant bacteria have been isolated from European starlings (Sturnus vulgaris), their role in the dissemination of antimicrobial resistant elements in livestock facilities needs further investigation. To determine whether on-farm starling density and other factors were associated with the presence of cefotaxime and ciprofloxacin resistant E. coli among dairy cows in Ohio, bovine fecal pats from 150 farms were tested for the presence of cefotaxime and ciprofloxacin resistant E. coli. Each farm was visited twice (during the summer and fall of 2007-2009). Multi-level logistic regression models with a random intercept to account for fecal pats collected within a specific visit to a farm were used to assess the associations. The percentage of samples with cefotaxime and ciprofloxacin resistant E. coli was 13.4% and 13.6%, respectively. The percentage of farms having at least one sample testing positive for cefotaxime and ciprofloxacin resistant E. coli was 56.7% and 48.7%, respectively. The odds of detecting cefotaxime and ciprofloxacin resistant E. coli in the samples was significantly higher in 2007 compared to 2008 and 2009, in fall compared to summer, and from farms closer than 60km to starling night roost sites compared to the farms further than 60km. The presence of starlings during the day had a negative association with the likelihood of detecting cefotaxime resistant E. coli. Presence of calves also had a negative association with the likelihood of detecting both cefotaxime and ciprofloxacin resistant E. coli. European starlings might play a role in the dissemination of antimicrobial resistant agents in livestock facilities related to their daily population movements rather than the specific density of birds on farm during the day. Copyright © 2016 Elsevier B.V. All rights reserved.

BnEPFL6, an EPIDERMAL PATTERNING FACTOR-LIKE (EPFL) secreted peptide gene, is required for filament elongation in Brassica napus.

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Huang, Yi; Tao, Zhangsheng; Liu, Qiong; Wang, Xinfa; Yu, Jingyin; Liu, Guihua; Wang, Hanzhong

2014-07-01

Inflorescence architecture, pedicel length and stomata patterning in Arabidopsis thaliana are specified by inter-tissue communication mediated by ERECTA and its signaling ligands in the EPIDERMAL PATTERNING FACTOR-LIKE (EPFL) family of secreted cysteine-rich peptides. Here, we identified and characterized BnEPFL6 from Brassica napus. Heterologous expression of this gene under the double enhanced CaMV promoter (D35S) in Arabidopsis resulted in shortened stamen filaments, filaments degradation, and reduced filament cell size that displayed down-regulated expression of AHK2, in which phenotypic variation of ahk2-1 mutant presented highly consistent with that of BnEPFL6 transgenic lines. Especially, the expression level of BnEPFL6 in the shortened filaments of four B. napus male sterile lines (98A, 86A, SA, and Z11A) was similar to that of BnEPFL6 in the transgenic Arabidopsis lines. The activity of pBnEPFL6.2::GUS was intensive in the filaments of transgenic lines. These observations reveal that BnEPFL6 plays an important role in filament elongation and may also affect organ morphology and floral organ specification via a BnEPFL6-mediated cascade.

The effect of heat and radiation on the initiation and elongation processes of DNA synthesis

International Nuclear Information System (INIS)

Davies, R.C.; Bowden, G.T.; Cress, A.E.

1983-01-01

The pH step alkaline elution and alkaline sucrose gradient techniques were utilized to evaluate alterations in DNA replication (initiation and elongation) induced by heat and low dose X-irradiation in synchronized Chinese hamster ovary cells. The initiation and elongation processes of DNA synthesis were radioresistant at the G 1 /S boundary (4 hours after mitosis) while in mid S phase (9 hours after mitosis) DNA initiation and elongation were sensitive to X-irradiation. The initiation and elongation processes of DNA synthesis which were radiation resistant at the G 1 /S boundary could be inhibited by a hyperthermia treatment (43 0 C for 1 hour beginning at 4 hours after mitosis). The impairment of initiation in the heated cells was maintained through late S phase while that of elongation was reversible as judged by full recovery at 15 hours after mitosis. These data suggest that the known synergistic lethality of heat and radiation may be mediated by an impairment of initiation of DNA synthesis. (author)

Codon usage regulates protein structure and function by affecting translation elongation speed in Drosophila cells.

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Zhao, Fangzhou; Yu, Chien-Hung; Liu, Yi

2017-08-21

Codon usage biases are found in all eukaryotic and prokaryotic genomes and have been proposed to regulate different aspects of translation process. Codon optimality has been shown to regulate translation elongation speed in fungal systems, but its effect on translation elongation speed in animal systems is not clear. In this study, we used a Drosophila cell-free translation system to directly compare the velocity of mRNA translation elongation. Our results demonstrate that optimal synonymous codons speed up translation elongation while non-optimal codons slow down translation. In addition, codon usage regulates ribosome movement and stalling on mRNA during translation. Finally, we show that codon usage affects protein structure and function in vitro and in Drosophila cells. Together, these results suggest that the effect of codon usage on translation elongation speed is a conserved mechanism from fungi to animals that can affect protein folding in eukaryotic organisms. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Restricted cell elongation in Arabidopsis hypocotyls is associated with a reduced average pectin esterification level.

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Derbyshire, Paul; McCann, Maureen C; Roberts, Keith

2007-06-17

Cell elongation is mainly limited by the extensibility of the cell wall. Dicotyledonous primary (growing) cell walls contain cellulose, xyloglucan, pectin and proteins, but little is known about how each polymer class contributes to the cell wall mechanical properties that control extensibility. We present evidence that the degree of pectin methyl-esterification (DE%) limits cell growth, and that a minimum level of about 60% DE is required for normal cell elongation in Arabidopsis hypocotyls. When the average DE% falls below this level, as in two gibberellic acid (GA) mutants ga1-3 and gai, and plants expressing pectin methyl-esterase (PME1) from Aspergillus aculeatus, then hypocotyl elongation is reduced. Low average levels of pectin DE% are associated with reduced cell elongation, implicating PMEs, the enzymes that regulate DE%, in the cell elongation process and in responses to GA. At high average DE% other components of the cell wall limit GA-induced growth.

Restricted cell elongation in Arabidopsis hypocotyls is associated with a reduced average pectin esterification level

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Derbyshire Paul

2007-06-01

Full Text Available Abstract Background Cell elongation is mainly limited by the extensibility of the cell wall. Dicotyledonous primary (growing cell walls contain cellulose, xyloglucan, pectin and proteins, but little is known about how each polymer class contributes to the cell wall mechanical properties that control extensibility. Results We present evidence that the degree of pectin methyl-esterification (DE% limits cell growth, and that a minimum level of about 60% DE is required for normal cell elongation in Arabidopsis hypocotyls. When the average DE% falls below this level, as in two gibberellic acid (GA mutants ga1-3 and gai, and plants expressing pectin methyl-esterase (PME1 from Aspergillus aculeatus, then hypocotyl elongation is reduced. Conclusion Low average levels of pectin DE% are associated with reduced cell elongation, implicating PMEs, the enzymes that regulate DE%, in the cell elongation process and in responses to GA. At high average DE% other components of the cell wall limit GA-induced growth.

Effect of hip and knee position on tensor fasciae latae elongation during stretching: An ultrasonic shear wave elastography study.

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Umehara, Jun; Ikezoe, Tome; Nishishita, Satoru; Nakamura, Masatoshi; Umegaki, Hiroki; Kobayashi, Takuya; Fujita, Kosuke; Ichihashi, Noriaki

2015-12-01

Decreased flexibility of the tensor fasciae latae is one factor that causes iliotibial band syndrome. Stretching has been used to improve flexibility or tightness of the muscle. However, no studies have investigated the effective stretching position for the tensor fasciae latae using an index to quantify muscle elongation in vivo. The aim of this study was to investigate the effects of hip rotation and knee angle on tensor fasciae latae elongation during stretching in vivo using ultrasonic shear wave elastography. Twenty healthy men participated in this study. The shear elastic modulus of the tensor fasciae latae was calculated using ultrasonic shear wave elastography. Stretching was performed at maximal hip adduction and maximal hip extension in 12 different positions with three hip rotation conditions (neutral, internal, and external rotations) and four knee angles (0°, 45°, 90°, and 135°). Two-way analysis of variance showed a significant main effect for knee angle, but not for hip rotation. The post-hoc test for knee angle indicated that the shear elastic modulus at 90° and 135° were significantly greater than those at 0° and 45°. Our results suggest that adding hip rotation to the stretching position with hip adduction and extension may have less effect on tensor fasciae latae elongation, and that stretching at >90° of knee flexion may effectively elongate the tensor fasciae latae. Copyright © 2015 Elsevier Ltd. All rights reserved.

Stereotypical reaching movements of the octopus involve both bend propagation and arm elongation.

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Hanassy, S; Botvinnik, A; Flash, T; Hochner, B

2015-05-13

The bend propagation involved in the stereotypical reaching movement of the octopus arm has been extensively studied. While these studies have analyzed the kinematics of bend propagation along the arm during its extension, possible length changes have been ignored. Here, the elongation profiles of the reaching movements of Octopus vulgaris were assessed using three-dimensional reconstructions. The analysis revealed that, in addition to bend propagation, arm extension movements involve elongation of the proximal part of the arm, i.e., the section from the base of the arm to the propagating bend. The elongations are quite substantial and highly variable, ranging from an average strain along the arm of -0.12 (i.e. shortening) up to 1.8 at the end of the movement (0.57 ± 0.41, n = 64 movements, four animals). Less variability was discovered in an additional set of experiments on reaching movements (0.64 ± 0.28, n = 30 movements, two animals), where target and octopus positions were kept more stationary. Visual observation and subsequent kinematic analysis suggest that the reaching movements can be broadly segregated into two groups. The first group involves bend propagation beginning at the base of the arm and propagating towards the arm tip. In the second, the bend is formed or present more distally and reaching is achieved mainly by elongation and straightening of the segment proximal to the bend. Only in the second type of movements is elongation significantly positively correlated with the distance of the bend from the target. We suggest that reaching towards a target is generated by a combination of both propagation of a bend along the arm and arm elongation. These two motor primitives may be combined to create a broad spectrum of reaching movements. The dynamical model, which recapitulates the biomechanics of the octopus muscular hydrostatic arm, suggests that achieving the observed elongation requires an extremely low ratio of longitudinal to transverse muscle

Crystallization and preliminary crystallographic analysis of the transcriptional regulator RfaH from Escherichia coli and its complex with ops DNA

International Nuclear Information System (INIS)

Vassylyeva, Marina N.; Svetlov, Vladimir; Klyuyev, Sergiy; Devedjiev, Yancho D.; Artsimovitch, Irina; Vassylyev, Dmitry G.

2006-01-01

The E. coli transcriptional regulator RfaH was cloned, expressed, purified and crystallized and the complex of RfaH with its target DNA oligonucleotide was cocrystallized. Complete diffraction data sets were collected for the apo protein and its nucleic acid complex at 2.4 and at 1.6 Å resolution, respectively. The bacterial transcriptional factor and virulence regulator RfaH binds to rapidly moving transcription elongation complexes through specific interactions with the exposed segment of the non-template DNA strand. To elucidate this unusual mechanism of recruitment, determination of the three-dimensional structure of RfaH and its complex with DNA was initiated. To this end, the Escherichia coli rfaH gene was cloned and expressed. The purified protein was crystallized by the sitting-drop vapor-diffusion technique. The space group was P6 1 22 or P6 5 22, with unit-cell parameters a = b = 45.46, c = 599.93 Å. A complex of RfaH and a nine-nucleotide oligodeoxyribonucleotide was crystallized by the same technique, but under different crystallization conditions, yielding crystals that belonged to space group P1 (unit-cell parameters a = 36.79, b = 44.01, c = 62.37 Å, α = 80.62, β = 75.37, γ = 75.41°). Complete diffraction data sets were collected for RfaH and its complex with DNA at 2.4 and 1.6 Å resolution, respectively. Crystals of selenomethionine-labeled proteins in both crystal forms were obtained by cross-microseeding using the native microcrystals. The structure determination of RfaH and its complex with DNA is in progress

A morphospace for reef fishes: elongation is the dominant axis of body shape evolution.

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Thomas Claverie

Full Text Available Tropical reef fishes are widely regarded as being perhaps the most morphologically diverse vertebrate assemblage on earth, yet much remains to be discovered about the scope and patterns of this diversity. We created a morphospace of 2,939 species spanning 56 families of tropical Indo-Pacific reef fishes and established the primary axes of body shape variation, the phylogenetic consistency of these patterns, and whether dominant patterns of shape change can be accomplished by diverse underlying changes. Principal component analysis showed a major axis of shape variation that contrasts deep-bodied species with slender, elongate forms. Furthermore, using custom methods to compare the elongation vector (axis that maximizes elongation deformation and the main vector of shape variation (first principal component for each family in the morphospace, we showed that two thirds of the families diversify along an axis of body elongation. Finally, a comparative analysis using a principal coordinate analysis based on the angles among first principal component vectors of each family shape showed that families accomplish changes in elongation with a wide range of underlying modifications. Some groups such as Pomacentridae and Lethrinidae undergo decreases in body depth with proportional increases in all body regions, while other families show disproportionate changes in the length of the head (e.g., Labridae, the trunk or caudal region in all combinations (e.g., Pempheridae and Pinguipedidae. In conclusion, we found that evolutionary changes in body shape along an axis of elongation dominates diversification in reef fishes. Changes in shape on this axis are thought to have immediate implications for swimming performance, defense from gape limited predators, suction feeding performance and access to some highly specialized habitats. The morphological modifications that underlie changes in elongation are highly diverse, suggesting a role for a range of

A Morphospace for Reef Fishes: Elongation Is the Dominant Axis of Body Shape Evolution

Science.gov (United States)

Claverie, Thomas; Wainwright, Peter C.

2014-01-01

Tropical reef fishes are widely regarded as being perhaps the most morphologically diverse vertebrate assemblage on earth, yet much remains to be discovered about the scope and patterns of this diversity. We created a morphospace of 2,939 species spanning 56 families of tropical Indo-Pacific reef fishes and established the primary axes of body shape variation, the phylogenetic consistency of these patterns, and whether dominant patterns of shape change can be accomplished by diverse underlying changes. Principal component analysis showed a major axis of shape variation that contrasts deep-bodied species with slender, elongate forms. Furthermore, using custom methods to compare the elongation vector (axis that maximizes elongation deformation) and the main vector of shape variation (first principal component) for each family in the morphospace, we showed that two thirds of the families diversify along an axis of body elongation. Finally, a comparative analysis using a principal coordinate analysis based on the angles among first principal component vectors of each family shape showed that families accomplish changes in elongation with a wide range of underlying modifications. Some groups such as Pomacentridae and Lethrinidae undergo decreases in body depth with proportional increases in all body regions, while other families show disproportionate changes in the length of the head (e.g., Labridae), the trunk or caudal region in all combinations (e.g., Pempheridae and Pinguipedidae). In conclusion, we found that evolutionary changes in body shape along an axis of elongation dominates diversification in reef fishes. Changes in shape on this axis are thought to have immediate implications for swimming performance, defense from gape limited predators, suction feeding performance and access to some highly specialized habitats. The morphological modifications that underlie changes in elongation are highly diverse, suggesting a role for a range of developmental processes

E. coli Surface Properties Differ between Stream Water and Sediment Environments

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Xiao Liang

2016-11-01

Full Text Available The importance of E. coli as an indicator organism in fresh water has led to numerous studies focusing on cell properties and transport behavior. However, previous studies have been unable to assess if differences in E. coli cell surface properties and genomic variation are associated with different environmental habitats. In this study, we investigated the variation in characteristics of E. coli obtained from stream water and stream bottom sediments. Cell properties were measured for 77 genomically different E. coli strains (44 strains isolated from sediments and 33 strains isolated from water under common stream conditions in the Upper Midwestern United States: pH 8.0, ionic strength 10mM and 22˚C. Measured cell properties include hydrophobicity, zeta potential, net charge, total acidity and extracellular polymeric substance (EPS composition. Our results indicate that stream sediment E. coli had significantly greater hydrophobicity, greater EPS protein content and EPS sugar content, less negative net charge, and higher point of zero charge than stream water E. coli. A significant positive correlation was observed between hydrophobicity and EPS protein for stream sediment E. coli but not for stream water E. coli. Additionally, E. coli surviving in the same habitat tended to have significantly larger (GTG5 genome similarity. After accounting for the intrinsic impact from the genome, environmental habitat was determined to be a factor influencing some cell surface properties, such as hydrophobicity. The diversity of cell properties and its resulting impact on particle interactions should be considered for environmental fate and transport modeling of aquatic indicator organisms such as E. coli.

E. coli Surface Properties Differ between Stream Water and Sediment Environments.

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Liang, Xiao; Liao, Chunyu; Thompson, Michael L; Soupir, Michelle L; Jarboe, Laura R; Dixon, Philip M

2016-01-01

The importance of E. coli as an indicator organism in fresh water has led to numerous studies focusing on cell properties and transport behavior. However, previous studies have been unable to assess if differences in E. coli cell surface properties and genomic variation are associated with different environmental habitats. In this study, we investigated the variation in characteristics of E. coli obtained from stream water and stream bottom sediments. Cell properties were measured for 77 genomically different E. coli strains (44 strains isolated from sediments and 33 strains isolated from water) under common stream conditions in the Upper Midwestern United States: pH 8.0, ionic strength 10 mM and 22°C. Measured cell properties include hydrophobicity, zeta potential, net charge, total acidity, and extracellular polymeric substance (EPS) composition. Our results indicate that stream sediment E. coli had significantly greater hydrophobicity, greater EPS protein content and EPS sugar content, less negative net charge, and higher point of zero charge than stream water E. coli . A significant positive correlation was observed between hydrophobicity and EPS protein for stream sediment E. coli but not for stream water E. coli . Additionally, E. coli surviving in the same habitat tended to have significantly larger (GTG) 5 genome similarity. After accounting for the intrinsic impact from the genome, environmental habitat was determined to be a factor influencing some cell surface properties, such as hydrophobicity. The diversity of cell properties and its resulting impact on particle interactions should be considered for environmental fate and transport modeling of aquatic indicator organisms such as E. coli .

E. Coli and Pregnancy

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... chat Live Help Fact Sheets Share Escherichia coli (E. coli) Friday, 01 September 2017 In every pregnancy, a ... risk. This sheet talks about whether exposure to E. coli may increase the risk for birth defects over ...

Reconstitution of active mycobacterial binuclear iron monooxygenase complex in Escherichia coli.

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Furuya, Toshiki; Hayashi, Mika; Kino, Kuniki

2013-10-01

Bacterial binuclear iron monooxygenases play numerous physiological roles in oxidative metabolism. Monooxygenases of this type found in actinomycetes also catalyze various useful reactions and have attracted much attention as oxidation biocatalysts. However, difficulties in expressing these multicomponent monooxygenases in heterologous hosts, particularly in Escherichia coli, have hampered the development of engineered oxidation biocatalysts. Here, we describe a strategy to functionally express the mycobacterial binuclear iron monooxygenase MimABCD in Escherichia coli. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of the mimABCD gene expression in E. coli revealed that the oxygenase components MimA and MimC were insoluble. Furthermore, although the reductase MimB was expressed at a low level in the soluble fraction of E. coli cells, a band corresponding to the coupling protein MimD was not evident. This situation rendered the transformed E. coli cells inactive. We found that the following factors are important for functional expression of MimABCD in E. coli: coexpression of the specific chaperonin MimG, which caused MimA and MimC to be soluble in E. coli cells, and the optimization of the mimD nucleotide sequence, which led to efficient expression of this gene product. These two remedies enabled this multicomponent monooxygenase to be actively expressed in E. coli. The strategy described here should be generally applicable to the E. coli expression of other actinomycetous binuclear iron monooxygenases and related enzymes and will accelerate the development of engineered oxidation biocatalysts for industrial processes.

The Acid Growth Theory of auxin-induced cell elongation is alive and well

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Rayle, D. L.; Cleland, R. E.

1992-01-01

Plant cells elongate irreversibly only when load-bearing bonds in the walls are cleaved. Auxin causes the elongation of stem and coleoptile cells by promoting wall loosening via cleavage of these bonds. This process may be coupled with the intercalation of new cell wall polymers. Because the primary site of auxin action appears to be the plasma membrane or some intracellular site, and wall loosening is extracellular, there must be communication between the protoplast and the wall. Some "wall-loosening factor" must be exported from auxin-impacted cells, which sets into motion the wall loosening events. About 20 years ago, it was suggested that the wall-loosening factor is hydrogen ions. This idea and subsequent supporting data gave rise to the Acid Growth Theory, which states that when exposed to auxin, susceptible cells excrete protons into the wall (apoplast) at an enhanced rate, resulting in a decrease in apoplastic pH. The lowered wall pH then activates wall-loosening processes, the precise nature of which is unknown. Because exogenous acid causes a transient (1-4 h) increase in growth rate, auxin must also mediate events in addition to wall acidification for growth to continue for an extended period of time. These events may include osmoregulation, cell wall synthesis, and maintenance of the capacity of walls to undergo acid-induced wall loosening. At present, we do not know if these phenomena are tightly coupled to wall acidification or if they are the products of multiple independent signal transduction pathways.

DNA damage regulates alternative splicing through changes in POL II elongation

International Nuclear Information System (INIS)

Munoz, M.J.; Perez Santangelo, M.S.; De la Mata, M.; Kornblihtt, A.R.

2008-01-01

Many apoptotic genes are regulated via alternative splicing (AS) but little is known about the mechanisms controlling AS in stress situations derived from DNA damage. Here we show that ultraviolet (UV) radiation affects co-transcriptional, but not post transcriptional, AS through a systemic mechanism involving a CDK-9-dependent hyper phosphorylation of RNA polymerase II carboxy terminal domain (CTD) and a subsequent and unprecedented inhibition of transcriptional elongation, estimated in vivo and in real time by FRAP. To mimic this hyper phosphorylation we used CTD mutants with serines 2 or 5 substituted by glutamic acids and found that they not only display lower elongation rates but duplicate the effects of UV light on AS in the absence of irradiation. Consistently, substitution of the serines with alanines prevents the UV effect on splicing. These results represent the first in vivo proof of modulation of elongation in response to an environmental signal, affecting in turn the kinetic coupling between transcription and splicing. (authors)

Growth of pulsed electric field exposed Escherichia coli in relation to inactivation and environmental factors.

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Aronsson, Kristina; Borch, Elisabeth; Stenlöf, Bo; Rönner, Ulf

2004-05-15

Pulsed electric fields (PEF) have been proven to inactivate microorganisms during nonthermal conditions and have the potential to replace thermal processing as a method for food preservation. However, there is a need to understand the recovery and growth of survivors and potentially injured microorganisms following PEF processing. The purpose of this investigation was to study the growth of Escherichia coli at 10 degrees C following exposure to electrical field strengths (15, 22.5 and 30 kV/cm) in relation to inactivation and the amount of potentially sublethally injured cells. One medium was used as both a treatment medium and an incubation medium, to study the influence of environmental factors on the inactivation and the growth of the surviving population. The pH (5.0, 6.0 and 7.0) and water activity (1.00, 0.985 and 0.97) of the medium was varied by adding HCl and glycerol, respectively. Growth was followed continuously by measuring the optical density. The time-to-detection (td) and the maximum specific growth rate (micromax) were calculated from these data. Results showed that the PEF process did not cause any obvious sublethal injury to the E. coli cells. The number of survivors was a consequence of the combination of electrical field strength and environmental factors, with pH being the most prominent. Interestingly, the micromax of subsequent growth was influenced by the applied electrical field strength during the process, with an increased micromax at more intense electrical field strengths. In addition, the micromax was also influenced by the pH and water activity. The td, which could theoretically be considered as an increase in shelf life, was found to depend on a complex correlation between electrical field strength, pH and water activity. That could be explained by the fact that the td is a combination of the number of survivors, the recovery of sublethal injured cells and the growth rate of the survivors. Copyright 2003 Elsevier B.V.

Diarrheagenic Escherichia coli Markers and Phenotypes among Fecal E. coli Isolates Collected from Nicaraguan Infants ▿

OpenAIRE

Reyes, Daniel; Vilchez, Samuel; Paniagua, Margarita; Colque-Navarro, Patricia; Weintraub, Andrej; Möllby, Roland; Kühn, Inger

2010-01-01

We analyzed the prevalence of diarrheagenic Escherichia coli (DEC) markers and common phenotypes in 2,164 E. coli isolates from 282 DEC-positive samples. Enteropathogenic E. coli (EPEC) and enteroaggregative E. coli (EAEC) were very diverse and were not correlated with diarrhea. Enterotoxigenic E. coli (ETEC) estA and enterohemorrhagic E. coli (EHEC) belonged to a few phenotypes and were significantly correlated with diarrhea.

[Virulence markers of Escherichia coli O1 strains].

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Makarova, M A; Kaftyreva, L A; Grigor'eva, N S; Kicha, E V; Lipatova, L A

2011-01-01

To detect virulence genes in clinical isolates of Escherichia coli O1 using polymerase chain reaction (PCR). One hundred and twenty strains of E.coli O1 strains isolated from faeces of patients with acute diarrhea (n = 45) and healthy persons (n = 75) were studied. PCR with primers for rfb and fliC genes, which control synthesis of O- and H- antigens respectively, was used. Fourteen virulence genes (pap, aaf, sfa, afa, eaeA, bfpA, ial, hly, cnf, stx1, stx2, lt, st, and aer) were detected by PCR primers. K1-antigen was determined by Pastorex Meningo B/E. coli O1 kit (Bio-Rad). rfb gene controlling O-antigen synthesis in serogroup O1 as well as fliC gene controlling synthesis of H7 and K1 antigens were detected in all strains. Thus all E. coli strains had antigenic structure O1:K1 :H-:F7. Virulence genes aafl, sfa, afa, eaeA, bfpA, ial, hly, cnf, stx1, stx2, lt, and st were not detected. All strains owned pap and aer genes regardless of the presence of acute diarrhea symptoms. It was shown that E. coli O1:KI:H-:F7 strains do not have virulence genes which are characteristic for diarrhea-causing Escherichia. In accordance with the presence of pap and aer genes they could be attributed to uropathogenic Escherichia (UPEC) or avian-pathogenic Escherichia (APEC). It is necessary to detect virulence factors in order to determine E. coli as a cause of intestinal infection.

Are lesions induced by ionizing radiation direct blocks to DNA chain elongation

International Nuclear Information System (INIS)

Painter, R.B.

1983-01-01

Ionizing radiation blocks DNA chain elongation in normal diploid fibroblasts but not in fibroblasts from patients with ataxia-telangiectasia, even though there are no differences in the damage induced between the two cell types. This difference suggests that radiation-induced lesions in DNA are not themselves blocks to chain elongation in ataxia cells and raises the possibility that in normal cells a mediator exists between DNA damage and chain termination

DNA Double Strand Break Response and Limited Repair Capacity in Mouse Elongated Spermatids

Directory of Open Access Journals (Sweden)

Emad A. Ahmed

2015-12-01

Full Text Available Spermatids are extremely sensitive to genotoxic exposures since during spermiogenesis only error-prone non homologous end joining (NHEJ repair pathways are available. Hence, genomic damage may accumulate in sperm and be transmitted to the zygote. Indirect, delayed DNA fragmentation and lesions associated with apoptotic-like processes have been observed during spermatid elongation, 27 days after irradiation. The proliferating spermatogonia and early meiotic prophase cells have been suggested to retain a memory of a radiation insult leading later to this delayed fragmentation. Here, we used meiotic spread preparations to localize phosphorylate histone H2 variant (γ-H2AX foci marking DNA double strand breaks (DSBs in elongated spermatids. This technique enabled us to determine the background level of DSB foci in elongated spermatids of RAD54/RAD54B double knockout (dko mice, severe combined immunodeficiency SCID mice, and poly adenosine diphosphate (ADP-ribose polymerase 1 (PARP1 inhibitor (DPQ-treated mice to compare them with the appropriate wild type controls. The repair kinetics data and the protein expression patterns observed indicate that the conventional NHEJ repair pathway is not available for elongated spermatids to repair the programmed and the IR-induced DSBs, reflecting the limited repair capacity of these cells. However, although elongated spermatids express the proteins of the alternative NHEJ, PARP1-inhibition had no effect on the repair kinetics after IR, suggesting that DNA damage may be passed onto sperm. Finally, our genetic mutant analysis suggests that an incomplete or defective meiotic recombinational repair of Spo11-induced DSBs may lead to a carry-over of the DSB damage or induce a delayed nuclear fragmentation during the sensitive programmed chromatin remodeling occurring in elongated spermatids.

Effect of bile on growth, peritoneal absorption, and blood clearance of Escherichia coli in E coli peritonitis

International Nuclear Information System (INIS)

Andersson, R.; Schalen, C.; Tranberg, K.G.

1991-01-01

The effect of intraperitoneal bile on growth, peritoneal absorption, and clearance of Escherichia coli was determined in E coli peritonitis in the rat. In E coli peritonitis, intraperitoneal bacterial counts gradually decreased, whereas they increased (after 2 hours) with subsequent development of bacteremia in E coli plus bile peritonitis. After an intraperitoneal injection of labeled bacteria, blood radioactivity was only initially lower in E coli plus bile peritonitis compared with E coli peritonitis. Clearance from blood was lower in E coli plus bile peritonitis than in E coli peritonitis. Organ localization was similar in E coli peritonitis and E coli plus bile peritonitis with decreased splenic, increased pulmonary, and unchanged hepatic uptakes compared with controls. Impaired peritoneal absorption of bacteria, together with impaired local host defense, is likely to enhance the noxious effect of bile in E coli peritonitis

Methanol as an alternative electron donor in chain elongation for butyrate and caproate formation

NARCIS (Netherlands)

Chen, W.S.; Ye, Y.; Steinbusch, K.J.J.; Strik, D.P.B.T.B.; Buisman, C.J.N.

2016-01-01

Chain elongation is an emerging mixed culture biotechnology converting acetate into valuable biochemicals by using ethanol as an external electron donor. In this study we proposed to test another potential electron donor, methanol, in chain elongation. Methanol can be produced through the

Suppression of vertical instability in elongated current-carrying plasmas by applying stellarator rotational transform

International Nuclear Information System (INIS)

ArchMiller, M. C.; Cianciosa, M. R.; Ennis, D. A.; Hanson, J. D.; Hartwell, G. J.; Hebert, J. D.; Herfindal, J. L.; Knowlton, S. F.; Ma, X.; Maurer, D. A.; Pandya, M. D.; Traverso, P.

2014-01-01

The passive stability of vertically elongated current-carrying toroidal plasmas has been investigated in the Compact Toroidal Hybrid, a stellarator/tokamak hybrid device. In this experiment, the fractional transform f, defined as the ratio of the imposed external rotational transform from stellarator coils to the total rotational transform, was varied from 0.04 to 0.50, and the elongation κ was varied from 1.4 to 2.2. Plasmas that were vertically unstable were evidenced by motion of the plasma in the vertical direction. Vertical drifts are measured with a set of poloidal field pickup coils. A three chord horizontally viewing interferometer and a soft X-ray diode array confirmed the drifts. Plasmas with low fractional transform and high elongation are the most susceptible to vertical instability, consistent with analytic predictions that the vertical mode in elongated plasmas can be stabilized by the poloidal field of a relatively weak stellarator equilibrium

Risk Factors for Antimicrobial Resistance in Escherichia coli in Pigs Receiving Oral Antimicrobial Treatment: A Systematic Review.

Science.gov (United States)

Burow, Elke; Käsbohrer, Annemarie

2017-03-01

The aim of this literature review was to identify risk factors in addition to antimicrobial treatment for antimicrobial resistance (AMR) occurrence in commensal Escherichia coli in pigs. A variety of studies were searched in 2014 and 2015. Studies identified as potentially relevant were assessed against eligibility criteria such as observation or experiment (no review), presentation of risk factors in addition to (single dosage) antimicrobial use, risk factors for but not resulting from AMR, and the same antimicrobial used and tested. Thirteen articles (nine on observational, four on experimental studies) were finally selected as relevant. It was reported that space allowance, production size/stage, cleanliness, entry of animals and humans into herds, dosage/frequency/route of administration, time span between treatment and sampling date, herd size, distance to another farm, coldness, and season had an impact on AMR occurrence. Associations were shown by one to four studies per factor and differed in magnitude, direction, and level of significance. The risk of bias was unclear in nearly half of the information of observational studies and in most of the information from experimental studies. Further research on the effects of specific management practices is needed to develop well-founded management advice.

Th2-related immune responses by the Brucella abortus cellular antigens, malate dehydrogenase, elongation factor, and arginase.

Science.gov (United States)

Im, Young Bin; Shim, Soojin; Park, Woo Bin; Kim, Suk; Yoo, Han Sang

2017-09-01

Brucellosis is an important zoonotic disease caused by Brucella species. The disease is difficult to control due to the intracellular survival of the bacterium and the lack of precise understanding of pathogenesis. Despite of continuous researches on the pathogenesis of Brucella spp. infection, there is still question on the pathogenesis, especially earlier immune response in the bacterial infection. Malate dehydrogenase (MDH), elongation factor (Tsf), and arginase (RocF), which showed serological reactivity, were purified after gene cloning, and their immune modulating activities were then analyzed in a murine model. Cytokine production profiles were investigated by stimulating RAW 264.7 cells and naïve splenocytes with the three recombinant proteins. Also, immune responses were analyzed by ELISA and an ELIspot assay after immunizing mice with the three proteins. Only TNF-α was produced in stimulated RAW 264.7 cells, whereas Th1-related cytokines, IFN-γ and IL-2, were induced in naïve splenocytes. In contrast, Th2-type immune response was more strongly induced in antigen-secreting cells in the splenocytes obtained 28 days after immunizing mice with the three proteins, as were IgM and IgG. The induction of Th2-related antibody, IgG1, was higher than the Th1-related antibody, IgG2a, in immunized mice. These results suggest that the three proteins strongly induce Th2-type immune response in vivo, even though Th1-related cytokines were produced in vitro. Copyright © 2017 Elsevier Ltd. All rights reserved.

Isolation and epidemiology of multidrug resistant Escherichia coli from goats in Cox's Bazar, Bangladesh

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Kamrul Islam

2016-06-01

Conclusion: Presence of MDR E. coli in the studied goats suggest the probable acquisition, development and transmission of MDR E. coli through a number of influencing factors to other animals and potentially to human. [J Adv Vet Anim Res 2016; 3(2.000: 166-172

Exposure to Sub-lethal 2,4-Dichlorophenoxyacetic Acid Arrests Cell Division and Alters Cell Surface Properties in Escherichia coli

Science.gov (United States)

Bhat, Supriya V.; Kamencic, Belma; Körnig, André; Shahina, Zinnat; Dahms, Tanya E. S.

2018-01-01

Escherichia coli is a robust, easily adaptable and culturable bacterium in vitro, and a model bacterium for studying the impact of xenobiotics in the environment. We have used correlative atomic force – laser scanning confocal microscopy (AFM-LSCM) to characterize the mechanisms of cellular response to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). One of the most extensively used herbicides world-wide, 2,4-D is known to cause hazardous effects in diverse non-target organisms. Sub-lethal concentrations of 2,4-D caused DNA damage in E. coli WM1074 during short exposure periods which increased significantly over time. In response to 2,4-D, FtsZ and FtsA relocalized within seconds, coinciding with the complete inhibition of cell septation and cell elongation. Exposure to 2,4-D also resulted in increased activation of the SOS response. Changes to cell division were accompanied by concomitant changes to surface roughness, elasticity and adhesion in a time-dependent manner. This is the first study describing the mechanistic details of 2,4-D at sub-lethal levels in bacteria. Our study suggests that 2,4-D arrests E. coli cell division within seconds after exposure by disrupting the divisome complex, facilitated by dissipation of membrane potential. Over longer exposures, 2,4-D causes filamentation as a result of an SOS response to oxidative stress induced DNA damage. PMID:29472899

Deficiency in L-serine deaminase interferes with one-carbon metabolism and cell wall synthesis in Escherichia coli K-12.

Science.gov (United States)

Zhang, Xiao; El-Hajj, Ziad W; Newman, Elaine

2010-10-01

Escherichia coli K-12 provided with glucose and a mixture of amino acids depletes L-serine more quickly than any other amino acid even in the presence of ammonium sulfate. A mutant without three 4Fe4S L-serine deaminases (SdaA, SdaB, and TdcG) of E. coli K-12 is unable to do this. The high level of L-serine that accumulates when such a mutant is exposed to amino acid mixtures starves the cells for C(1) units and interferes with cell wall synthesis. We suggest that at high concentrations, L-serine decreases synthesis of UDP-N-acetylmuramate-L-alanine by the murC-encoded ligase, weakening the cell wall and producing misshapen cells and lysis. The inhibition by high L-serine is overcome in several ways: by a large concentration of L-alanine, by overproducing MurC together with a low concentration of L-alanine, and by overproducing FtsW, thus promoting septal assembly and also by overexpression of the glycine cleavage operon. S-Adenosylmethionine reduces lysis and allows an extensive increase in biomass without improving cell division. This suggests that E. coli has a metabolic trigger for cell division. Without that reaction, if no other inhibition occurs, other metabolic functions can continue and cells can elongate and replicate their DNA, reaching at least 180 times their usual length, but cannot divide.

Design and application of transcription factor based metabolite sensors in Escherichia coli

DEFF Research Database (Denmark)

Siedler, Solvej; Stahlhut, Steen Gustav; Bringer, Stephanie

2014-01-01

SoxR that activates expression of soxS in the absence of NADPH in Escherichia coli. We coupled the response to the expression of an auto fluorescent protein and the specific fluorescence of sensor containing cells correlated with enzyme activity of an NADPH-dependent alcohol dehydrogenase from...

The high temperature out-of-pile test of LVDT for elongation measurement of fuel pellet

Energy Technology Data Exchange (ETDEWEB)

Son, J. M.; Kim, B. K.; Jo, M. S.; Joo, K. N.; Park, S. J.; Gang, Y. H.; Kim, Y. J. [KAERI, Taejon (Korea, Republic of)

2003-10-01

As a part of the development of instrumentation technologies for the nuclear fuel irradiation test in HANARO(High-flux Advanced Nuclear Application Reactor), the elongation measurement technique of the fuel pellet is being developed using LVDT(Linear Variable Differential Transformer). The well qualified out-of-pile test were needed to understand the LVDT's detail characteristics at high temperature for the detail design of the fuel irradiation instrumented capsule, because LVDT is very sensitive to variation of temperature. Therefore, the high temperature out-of-pile test system for fuel pellet elongation was developed, and this test was performed under the temperature condition between room temperature and 300 .deg. C with increasing the elongation from 0 to 5 mm. The LVDT's high temperature characteristics and temperature sensitivity of LVDT were analyzed through this experiment. Based on the result of this test, the method for the application of LVDT and elongation detector at high temperature was introduced. It is known that the results will be used to predict accurately the elongation of fuel pellet during irradiation test.

Detection of virulence genes and the phylogenetic groups of Escherichia coli isolated from dogs in Brazil

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Fernanda Morcatti Coura

2018-02-01

Full Text Available ABSTRACT: This study identified the virulence genes, pathovars, and phylogenetic groups of Escherichia coli strains obtained from the feces of dogs with and without diarrhea. Virulence genes and phylogenetic group identification were studied using polymerase chain reaction. Thirty-seven E. coli isolates were positive for at least one virulence factor gene. Twenty-one (57.8% of the positive isolates were isolated from diarrheal feces and sixteen (43.2% were from the feces of non-diarrheic dogs. Enteropathogenic E. coli (EPEC were the most frequently (62.2% detected pathovar in dog feces and were mainly from phylogroup B1 and E. Necrotoxigenic E. coli were detected in 16.2% of the virulence-positive isolates and these contained the cytotoxic necrotizing factor 1 (cnf1 gene and were classified into phylogroups B2 and D. All E. coli strains were negative for the presence of enterotoxigenic E. coli (ETEC enterotoxin genes, but four strains were positive for ETEC-related fimbriae 987P and F18. Two isolates were Shiga toxin-producing E. coli strains and contained the toxin genesStx2 or Stx2e, both from phylogroup B1. Our data showed that EPEC was the most frequent pathovar and B1 and E were the most common phylogroups detected in E. coli isolated from the feces of diarrheic and non-diarrheic dogs.

Expression and cytoprotective activity of the small GTPase RhoB induced by the Escherichia coli cytotoxic necrotizing factor 1

DEFF Research Database (Denmark)

Huelsenbeck, Stefanie C; Roggenkamp, Dennis; May, Martin

2013-01-01

B expression, based on the inactivation of Rho/Ras proteins. In this study, we report on a long lasting expression of RhoB in cultured cells upon activation of Rho proteins by the cytotoxic necrotizing factor 1 (CNF1) from Escherichia coli. The observations of this study highlight a new pathway involving Rac1...... without any signs of cell death. In conclusion, the cytoprotective RhoB response is not only evoked by bacterial protein toxins inactivating Rho/Ras proteins but also by the Rac1-activating toxin CNF1....

Influence of ovarian muscle contraction and oocyte growth on egg chamber elongation in Drosophila.

Science.gov (United States)

Andersen, Darcy; Horne-Badovinac, Sally

2016-04-15

Organs are formed from multiple cell types that make distinct contributions to their shape. The Drosophila egg chamber provides a tractable model to dissect such contributions during morphogenesis. Egg chambers consist of 16 germ cells (GCs) surrounded by a somatic epithelium. Initially spherical, these structures elongate as they mature. This morphogenesis is thought to occur through a 'molecular corset' mechanism, whereby structural elements within the epithelium become circumferentially organized perpendicular to the elongation axis and resist the expansive growth of the GCs to promote elongation. Whether this epithelial organization provides the hypothesized constraining force has been difficult to discern, however, and a role for GC growth has not been demonstrated. Here, we provide evidence for this mechanism by altering the contractile activity of the tubular muscle sheath that surrounds developing egg chambers. Muscle hypo-contraction indirectly reduces GC growth and shortens the egg, which demonstrates the necessity of GC growth for elongation. Conversely, muscle hyper-contraction enhances the elongation program. Although this is an abnormal function for this muscle, this observation suggests that a corset-like force from the egg chamber's exterior could promote its lengthening. These findings highlight how physical contributions from several cell types are integrated to shape an organ. © 2016. Published by The Company of Biologists Ltd.

Experimental Evolution of Escherichia coli Harboring an Ancient Translation Protein.

Science.gov (United States)

Kacar, Betül; Ge, Xueliang; Sanyal, Suparna; Gaucher, Eric A

2017-03-01

The ability to design synthetic genes and engineer biological systems at the genome scale opens new means by which to characterize phenotypic states and the responses of biological systems to perturbations. One emerging method involves inserting artificial genes into bacterial genomes and examining how the genome and its new genes adapt to each other. Here we report the development and implementation of a modified approach to this method, in which phylogenetically inferred genes are inserted into a microbial genome, and laboratory evolution is then used to examine the adaptive potential of the resulting hybrid genome. Specifically, we engineered an approximately 700-million-year-old inferred ancestral variant of tufB, an essential gene encoding elongation factor Tu, and inserted it in a modern Escherichia coli genome in place of the native tufB gene. While the ancient homolog was not lethal to the cell, it did cause a twofold decrease in organismal fitness, mainly due to reduced protein dosage. We subsequently evolved replicate hybrid bacterial populations for 2000 generations in the laboratory and examined the adaptive response via fitness assays, whole genome sequencing, proteomics, and biochemical assays. Hybrid lineages exhibit a general adaptive strategy in which the fitness cost of the ancient gene was ameliorated in part by upregulation of protein production. Our results suggest that an ancient-modern recombinant method may pave the way for the synthesis of organisms that exhibit ancient phenotypes, and that laboratory evolution of these organisms may prove useful in elucidating insights into historical adaptive processes.

Elongational viscosity of monodisperse and bidisperse polystyrene melts

DEFF Research Database (Denmark)

Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz; Hassager, Ole

2005-01-01

The startup and steady uniaxial elongational viscosity have been measured for two monodisperse polystyrene melts with molecular weights of 52 kg/mole (PS52K) and 103 kg/mole (PS103K), and for three bidisperse polystyrene melts. The bidisperse melts consist of PS103K or PS52K and a monodisperse...... (closed loop proportional regulator) using the laser in such a way that the stretch rate at the neck is kept constant. The rheometer has been described in more detail in (A. Bach, H.K. Rasmussen and O. Hassager, Journal of Rheology, 47 (2003) 429). PS390K show a decrease in the steady viscosity as a power......-law function of the elongational rate (A. Bach, K. Almdal, H.K. Rasmussen and O. Hassager, Macromolecules 36 (2003) 5174). PS52K and PS103K show that the steady viscosity has a maximum that is respectively 100% and 50% above 3 times the zero-shear-rate viscosity. The bidisperse melts show a significant...

Hamstring Elongation Quantified Using Ultrasonography During the Straight Leg Raise Test in Individuals With Low Back Pain.

Science.gov (United States)

Kellis, Eleftherios; Ellinoudis, Athanasios; Kofotolis, Nikolaos

2015-06-01

Although the straight leg raise (SLR) test frequently is used to assess hamstring extensibility in individuals with low back pain (LBP), evidence relating LBP, SLR, and hamstring extensibility remains unclear. The SLR measures the angle between the lifted leg and the horizontal, however, and, as such, it is not a direct measure of the elongation capacity of the hamstrings. To examine the differences in hamstring elongation (quantified via ultrasonography) and SLR score between individuals with LBP and asymptomatic controls and to determine the relationship between hamstring elongation, SLR, and functional disability scores. Cross-sectional study. University laboratory. Forty men and women with chronic LBP (mean ± SD, age 43.51 ± 3.71 years and 40 control subjects (age 45.11 ± 4.01 years) participated in this study. Passive SLR, elongation assessed via ultrasonography, and functional disability. SLR score, elongation of tendinous tissue within the semitendinosus muscle, and Oswestry Disability Index. Two-way analysis of variance tests indicated a significantly lower SLR score and a greater Oswestry score in LBP group compared with control subjects (P hamstring elongation (P > .05). Gender did not have an effect on all dependent measures (P > .05). Hamstring elongation showed a low correlation with SLR score and a minimal correlation with Oswestry score. These results indicate that the SLR score is not determined by hamstring elongation (quantified via ultrasonography). Copyright © 2015 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Methanofullerene elongated nanostructure formation for enhanced organic solar cells

Energy Technology Data Exchange (ETDEWEB)

Reyes-Reyes, M. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico)], E-mail: reyesm@cactus.iico.uaslp.mx; Lopez-Sandoval, R. [Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la presa San Jose 2055, CP 78216. San Luis Potosi (Mexico); Arenas-Alatorre, J. [Instituto de Fisica, UNAM, Apartado Postal 20-364, 01000, Mexico, D.F. (Mexico); Garibay-Alonso, R. [Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la presa San Jose 2055, CP 78216. San Luis Potosi (Mexico); Carroll, D.L. [Center for Nanotechnology and Molecular Materials, Department of Physics. Wake Forest University, Winston-Salem NC 27109 (United States); Lastras-Martinez, A. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico)

2007-11-01

Using transmission electron microscopy (TEM) and Z-contrast imaging we have demonstrated elongated nanostructure formation of fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) within an organic host through annealing. The annealing provides an enhanced mobility of the PCBM molecules and, with good initial dispersion, allows for the formation of exaggerated grain growth within the polymer host. We have assembled these nanostructures within the regioregular conjugated polymer poly(3-hexylthiophene) (P3HT). This PCBM elongated nanostructure formation maybe responsible for the very high efficiencies observed, at very low loadings of PCBM (1:0.6, polymer to PCBM), in annealed photovoltaics. Moreover, our high resolution TEM and electron energy loss spectroscopy studies clearly show that the PCBM crystals remain crystalline and are unaffected by the 200-keV electron beam.

Methanofullerene elongated nanostructure formation for enhanced organic solar cells

International Nuclear Information System (INIS)

Reyes-Reyes, M.; Lopez-Sandoval, R.; Arenas-Alatorre, J.; Garibay-Alonso, R.; Carroll, D.L.; Lastras-Martinez, A.

2007-01-01

Using transmission electron microscopy (TEM) and Z-contrast imaging we have demonstrated elongated nanostructure formation of fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) within an organic host through annealing. The annealing provides an enhanced mobility of the PCBM molecules and, with good initial dispersion, allows for the formation of exaggerated grain growth within the polymer host. We have assembled these nanostructures within the regioregular conjugated polymer poly(3-hexylthiophene) (P3HT). This PCBM elongated nanostructure formation maybe responsible for the very high efficiencies observed, at very low loadings of PCBM (1:0.6, polymer to PCBM), in annealed photovoltaics. Moreover, our high resolution TEM and electron energy loss spectroscopy studies clearly show that the PCBM crystals remain crystalline and are unaffected by the 200-keV electron beam

The upper surface of an Escherichia coli swarm is stationary.

Science.gov (United States)

Zhang, Rongjing; Turner, Linda; Berg, Howard C

2010-01-05

When grown in a rich medium on agar, many bacteria elongate, produce more flagella, and swim in a thin film of fluid over the agar surface in swirling packs. Cells that spread in this way are said to swarm. The agar is a solid gel, with pores smaller than the bacteria, so the swarm/agar interface is fixed. Here we show, in experiments with Escherichia coli, that the swarm/air interface also is fixed. We deposited MgO smoke particles on the top surface of an E. coli swarm near its advancing edge, where cells move in a single layer, and then followed the motion of the particles by dark-field microscopy and the motion of the underlying cells by phase-contrast microscopy. Remarkably, the smoke particles remained fixed (diffusing only a few micrometers) while the swarming cells streamed past underneath. The diffusion coefficients of the smoke particles were smaller over the virgin agar ahead of the swarm than over the swarm itself. Changes between these two modes of behavior were evident within 10-20 microm of the swarm edge, indicating an increase in depth of the fluid in advance of the swarm. The only plausible way that the swarm/air interface can be fixed is that it is covered by a surfactant monolayer pinned at its edges. When a swarm is exposed to air, such a monolayer can markedly reduce water loss. When cells invade tissue, the ability to move rapidly between closely opposed fixed surfaces is a useful trait.

Building a complete image of genome regulation in the model organism Escherichia coli.

Science.gov (United States)

Ishihama, Akira

2018-01-15

The model organism, Escherichia coli, contains a total of more than 4,500 genes, but the total number of RNA polymerase (RNAP) core enzyme or the transcriptase is only about 2,000 molecules per genome. The regulatory targets of RNAP are, however, modulated by changing its promoter selectivity through two-steps of protein-protein interplay with 7 species of the sigma factor in the first step, and then 300 species of the transcription factor (TF) in the second step. Scientists working in the field of prokaryotic transcription in Japan have made considerable contributions to the elucidation of genetic frameworks and regulatory modes of the genome transcription in E. coli K-12. This review summarizes the findings by this group, first focusing on three sigma factors, the stationary-phase sigma RpoS, the heat-shock sigma RpoH, and the flagellar-chemotaxis sigma RpoF, as examples. It also presents an overview of the current state of the systematic research being carried out to identify the regulatory functions of all TFs from a single and the same bacterium E. coli K-12, using the genomic SELEX and PS-TF screening systems. All these studies have been undertaken with the aim of understanding the genome regulation in E. coli K-12 as a whole.

Applied force and elongation in the medial rectus in esotropic patients with and without movement restriction.

Science.gov (United States)

Krieger, Fernanda; Cvintal, Tadeu; Bicas, Harley

2004-12-01

To study the different ways of expressing the force-elongation relationship in medial rectus muscles in esotropia with and without muscular restriction. Twenty-nine passive force-elongation curves were obtained without restriction (group I, n = 13) and with restriction (group II, n = 10) by means of a manual pachymeter and a digital dynamometer. In group I, the mean age was 14 years and 7 days and the mean esotropia was 53.88(Delta) while in group II the mean age was 35 years and 5 days and the mean esotropia was 60.5(Delta). Comparisons of structural muscular parameters between groups I and II were made for length (38.69 +/- 0.75 vs. 32.48 +/- 1.84 mm, p elongation relationship, whether normalized or not, followed an exponential curve. The constant c, which represents force when the elongation is zero, remained the same in all curves. In contrast, the constant b, which represents the slope of the curve, showed a significant difference between the two groups only for the curves of force-absolute elongation and tension-absolute elongation. The results imply that the constant b is better for characterizing the difference between the behavior of the medial rectus in esotropia with and without restriction. In addition, the elongation normalization showed that the contractile component is similar between the two groups and, therefore, the classical way of analysis, which does not employ normalization, is appropriate to correlate muscle properties with clinical findings.

Antibiotic resistance, virulence factors and biofilm formation ability in Escherichia coli strains isolated from chicken meat and wildlife in the Czech Republic.

Science.gov (United States)

Pavlickova, Silvie; Klancnik, Anja; Dolezalova, Magda; Mozina, Sonja Smole; Holko, Ivan

2017-08-03

Attachment of pathogenic bacteria to food contact surfaces and the subsequent biofilm formation represent a serious threat for the food industry, since these bacteria are more resistant to antimicrobials or possess more virulence factors. The main aim of this study was to investigate the correlation between antibiotic resistance against 13 antibiotics, distribution of 10 virulence factors and biofilm formation in 105 Escherichia coli strains according to their origin. The high prevalence of antibiotic resistance that we have found in wildlife isolates could be acquired by horizontal transfer of resistance genes from human or domestic or farm animals. Consequently, these commensal bacteria might serve as indicator of antimicrobial usage for human and veterinary purposes in the Czech Republic. Further, 46 out of 66 resistant isolates (70%) were able to form biofilm and we found out statistically significant correlation between prevalence of antibiotic resistance and biofilm formation ability. The highest prevalence of antibiotic resistance was observed in weak biofilm producers. Biofilm formation was not statistically associated with any virulence determinant. However, we confirmed the correlation between prevalence of virulence factors and host origin. Chicken isolates possessed more virulence factors (66%), than isolates from wildlife (37%). We can conclude that the potential spread of antibiotic resistance pattern via the food chain is of high concern for public health. Even more, alarming is that E. coli isolates remain pathogenic potential with ability to form biofilm and these bacteria may persist during food processing and consequently lead to greater risks of food contamination.

High Efficient Expression, Purification, and Functional Characterization of Native Human Epidermal Growth Factor in Escherichia coli

Directory of Open Access Journals (Sweden)

Yi Ma

2016-01-01

Full Text Available Human epidermal growth factor (hEGF is a small, mitotic growth polypeptide that promotes the proliferation of various cells and is widely applied in clinical practices. However, high efficient expression of native hEGF in Escherichia coli has not been successful, since three disulfide bonds in monomer hEGF made it unable to fold into correct 3D structure using in vivo system. To tackle this problem, we fused Mxe GyrA intein (Mxe at the C-terminal of hEGF followed by small ubiquitin-related modifier (SUMO and 10x His-tag to construct a chimeric protein hEGF-Mxe-SUMO-H10. The fusion protein was highly expressed at the concentration of 281 mg/L and up to 59.5% of the total cellular soluble proteins. The fusion protein was purified by affinity chromatography and 29.4 mg/L of native hEGF can be released by thiol induced N-terminal cleavage without any proteases. The mitotic activity in Balb/c 3T3 cells is proliferated by commercial and recombinant hEGF measured with methylthiazolyldiphenyl-tetrazolium bromide (MTT assay which indicated that recombinant hEGF protein stimulates the cell proliferation similar to commercial protein. This study significantly improved the yield and reduced the cost of hEGF in the recombinant E. coli system and could be a better strategy to produce native hEGF for pharmaceutical development.

High Efficient Expression, Purification, and Functional Characterization of Native Human Epidermal Growth Factor in Escherichia coli.

Science.gov (United States)

Ma, Yi; Yu, Jieying; Lin, Jinglian; Wu, Shaomin; Li, Shan; Wang, Jufang

2016-01-01

Human epidermal growth factor (hEGF) is a small, mitotic growth polypeptide that promotes the proliferation of various cells and is widely applied in clinical practices. However, high efficient expression of native hEGF in Escherichia coli has not been successful, since three disulfide bonds in monomer hEGF made it unable to fold into correct 3D structure using in vivo system. To tackle this problem, we fused Mxe GyrA intein (Mxe) at the C-terminal of hEGF followed by small ubiquitin-related modifier (SUMO) and 10x His-tag to construct a chimeric protein hEGF-Mxe-SUMO-H 10 . The fusion protein was highly expressed at the concentration of 281 mg/L and up to 59.5% of the total cellular soluble proteins. The fusion protein was purified by affinity chromatography and 29.4 mg/L of native hEGF can be released by thiol induced N-terminal cleavage without any proteases. The mitotic activity in Balb/c 3T3 cells is proliferated by commercial and recombinant hEGF measured with methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay which indicated that recombinant hEGF protein stimulates the cell proliferation similar to commercial protein. This study significantly improved the yield and reduced the cost of hEGF in the recombinant E. coli system and could be a better strategy to produce native hEGF for pharmaceutical development.

DNA barcoding for identification of 'Candidatus Phytoplasmas' using a fragment of the elongation factor Tu gene.

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Olga Makarova

Full Text Available Phytoplasmas are bacterial phytopathogens responsible for significant losses in agricultural production worldwide. Several molecular markers are available for identification of groups or strains of phytoplasmas. However, they often cannot be used for identification of phytoplasmas from different groups simultaneously or are too long for routine diagnostics. DNA barcoding recently emerged as a convenient tool for species identification. Here, the development of a universal DNA barcode based on the elongation factor Tu (tuf gene for phytoplasma identification is reported.We designed a new set of primers and amplified a 420-444 bp fragment of tuf from all 91 phytoplasmas strains tested (16S rRNA groups -I through -VII, -IX through -XII, -XV, and -XX. Comparison of NJ trees constructed from the tuf barcode and a 1.2 kbp fragment of the 16S ribosomal gene revealed that the tuf tree is highly congruent with the 16S rRNA tree and had higher inter- and intra- group sequence divergence. Mean K2P inter-/intra- group divergences of the tuf barcode did not overlap and had approximately one order of magnitude difference for most groups, suggesting the presence of a DNA barcoding gap. The use of the tuf barcode allowed separation of main ribosomal groups and most of their subgroups. Phytoplasma tuf barcodes were deposited in the NCBI GenBank and Q-bank databases.This study demonstrates that DNA barcoding principles can be applied for identification of phytoplasmas. Our findings suggest that the tuf barcode performs as well or better than a 1.2 kbp fragment of the 16S rRNA gene and thus provides an easy procedure for phytoplasma identification. The obtained sequences were used to create a publicly available reference database that can be used by plant health services and researchers for online phytoplasma identification.

Extensive proteomic remodeling is induced by eukaryotic translation elongation factor 1Bγ deletion in Aspergillus fumigatus.

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O'Keeffe, Grainne; Jöchl, Christoph; Kavanagh, Kevin; Doyle, Sean

2013-11-01

The opportunistic pathogen Aspergillus fumigatus is ubiquitous in the environment and predominantly infects immunocompromised patients. The functions of many genes remain unknown despite sequencing of the fungal genome. A putative translation elongation factor 1Bγ (eEF1Bγ, termed elfA; 750 bp) is expressed, and exhibits glutathione S-transferase activity, in A. fumigatus. Here, we demonstrate the role of ElfA in the oxidative stress response, as well as a possible involvement in translation and actin cytoskeleton organization, respectively. Comparative proteomics, in addition to phenotypic analysis, under basal and oxidative stress conditions, demonstrated a role for A. fumigatus elfA in the oxidative stress response. An elfA-deficient strain (A. fumigatus ΔelfA) was significantly more sensitive to the oxidants H2O2, diamide, and 4,4'-dipyridyl disulfide (DPS) than the wild-type. This was further supported with the identification of differentially expressed proteins of the oxidative stress response, including; mitochondrial peroxiredoxin Prx1, molecular chaperone Hsp70 and mitochondrial glycerol-3-phosphate dehydrogenase. Phenotypic analysis also revealed that A. fumigatus ΔelfA was significantly more tolerant to voriconazole than the wild-type. The differential expression of two aminoacyl-tRNA synthetases suggests a role for A. fumigatus elfA in translation, while the identification of actin-bundling protein Sac6 and vacuolar dynamin-like GTPase VpsA link A. fumigatus elfA to the actin cytoskeleton. Overall, this work highlights the diverse roles of A. fumigatus elfA, with respect to translation, oxidative stress and actin cytoskeleton organization. In addition to this, the strategy of combining targeted gene deletion with comparative proteomics for elucidating the role of proteins of unknown function is further revealed. © 2013 The Protein Society.

Germination and root elongation bioassays in six different plant species for testing Ni contamination in soil.

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Visioli, Giovanna; Conti, Federica D; Gardi, Ciro; Menta, Cristina

2014-04-01

In vitro short-term chronic phytotoxicity germination and root elongation test were applied to test the effects of nickel (Ni) in seed germination and root elongation in six plants species: Cucumis sativus (Cucurbitaceae), Lepidium sativum and Brassica nigra (Brassicaceae), Trifolium alexandrinum and Medicago sativa (Fabaceae), Phacelia tanacetifolia (Boraginaceae). A naturally Ni rich soil was used to compare the results obtained. Unlike root elongation, germination was not affected by Ni in any of the six species tested. EC50 values, calculated on the root elongation, showed that Ni toxicity decreases in the following order: P. tanacetifolia > B. nigra > C. sativus > L. sativum > M. sativa > T. alexandrinum. The test conducted using soil elutriate revealed a significantly lower effect in both seed germination and root elongation when compared to the results obtained using untreated soil. Conversely, the test performed on soil confirmed the high sensitivity of C. sativus, P. tanacetifolia and L. sativum to Ni.

Evaluation of TG-43 recommended 2D-anisotropy function for elongated brachytherapy sources

International Nuclear Information System (INIS)

Awan, Shahid B.; Meigooni, Ali S.; Mokhberiosgouei, Ramin; Hussain, Manzoor

2006-01-01

The original and updated protocols recommended by Task Group 43 from the American Association of Physicists in Medicine (i.e., TG-43 and TG-43U1, respectively), have been introduced to unify brachytherapy source dosimetry around the world. Both of these protocols are based on experiences with sources less than 1.0 cm in length. TG-43U1 recommends that for 103 Pd sources, 2D anisotropy function F(r,θ), should be tabulated at a minimum for radial distances of 0.5, 1.0, 2.0, 3.0, and 5.0 cm. Anisotropy functions defined in these protocols are only valid when the point of calculation does not fall on the active length of the source. However, for elongated brachytherapy sources (active length >1 cm), some of the calculation points with r 103 Pd source at radial distances of 2.5, 3.0, and 4.0 cm were 2.95, 1.74, and 1.19, respectively, with differences up to about a factor of 3. Therefore, the validity of the linear interpolation technique for an elongated brachytherapy source with such a large variation in F(r,θ) needs to be investigated. In this project, application of the TG-43U1 formalism for dose calculation around an elongated RadioCoil trade mark sign 103 Pd brachytherapy source has been investigated. In addition, the linear interpolation techniques as described in TG-43U1 for seed type sources have been evaluated for a 5.0 cm long RadioCoil trade mark sign 103 Pd brachytherapy source. Application of a polynomial fit to F(r,θ) has also been investigated as an alternate approach to the linear interpolation technique. The results of these investigations indicate that the TG-43U1 formalism can be extended for elongated brachytherapy sources, if the two-dimensional (2D) anisotropy function is tabulated at a minimum for radial distances of 0.2, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 cm, L/2, and L/2±0.2 cm. Moreover, with the addition of recommended radial distances for 2D anisotropy functions, the linear interpolation technique more closely replicates

Escherichia coli : host interactions in the pathogenesis of canine pyometra

OpenAIRE

Henriques, Sofia Correia Rosa de Barros

2016-01-01

Tese de Doutoramento em Ciências Veterinárias na Especialidade de Ciências Biológicas e Biomédicas Canine pyometra develops as a result of a complex interaction of etiological and physiopathological factors, such as the virulence and type of the bacteria and the individual host defence mechanisms. Since Escherichia coli is the most common bacterium isolated from uterus of bitches with pyometra, one main objective of this work was to characterize E. coli virulence potential, and...

Molecular detection and antimicrobial resistance of diarrheagenic Escherichia coli strains isolated from diarrheal cases

International Nuclear Information System (INIS)

Aslani, Mehdi M.; Salmanzadeh-Ahrabi, S.; Jafari, F.; Zali, Reza M.; Mani, M.; Alikhani, Yousef M.

2008-01-01

Objective was to identify and classify Iranian isolates of diarrheagenic Escherichia coli (E. coli) on the basis of presence of virulence genes and to determine antibiotic susceptibility of isolated strains. The current cross-sectional study was conducted in 2005 at the Pasteur Institute, Tehran, Iran. One hundred and ninety-three diarrheagenic E. coli isolated from diarrheal patients in different regions of Iran were included in current study. Virulence factors genees for diarrheagenic E. coli were detected by polymerase chain reaction. Of the 193 diarrheagenic E. coli detected by PCR, 86(44.5%) were Shiga toxin-producing E. coli (STEC), 74 (38.4%) enteropathogenic E. coli (EPEC), 19 (9.8%) enteroaggregative E. coli and 14 (7.3%) enterotoxigenic E. coli isolates. Susceptibility to 12 clinically important antimicrobial agents was determined for 193 strains of diarrhheagenic E. coli. A high incidence of resistance to tetracycline (63%), ampicillin (62%), streptomycin (56%), amoxicillin/clavulanic acid (44.5%), trimetoprim/sulphamethoxazole (39.5%) and cephalothin (37%) was observed. The STEC and EPEC strains with high resistance to tetracycline and ampicillin but highly susceptible to quinolones are among the most important causative agent of diarrhea in Iran. This study suggests that antimicrobial resistance is wide spread among E. coli strains colonizing Iranian patients. Guidelines for appropriate use of antibiotics in developing countries require updating. (author)

Adiabatic compression of elongated field-reversed configurations

International Nuclear Information System (INIS)

Spencer, R.L.; Tuszewski, M.; Linford, R.K.

1983-01-01

The adiabatic compression of an elongated field-reversed configuration (FRC) is computed by using a one-dimensional approximation. The one-dimensional results are checked against a two-dimensional equilibrium code. For ratios of FRC separatrix length to separatrix radius greater than about ten, the one-dimensional results are accurate within 10%. To this accuracy, the adiabatic compression of FRC's can be described by simple analytic formulas

Improving the Determination of Eastern Elongations of Planetary Satellites in the Astronomical Almanac

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Rura, Christopher; Stollberg, Mark

2018-01-01

The Astronomical Almanac is an annual publication of the US Naval Observatory (USNO) and contains a wide variety of astronomical data used by astronomers worldwide as a general reference or for planning observations. Included in this almanac are the times of greatest eastern and northern elongations of the natural satellites of the planets, accurate to 0.1 hour UT. The production code currently used to determine elongation times generates X and Y coordinates for each satellite (16 total) in 5 second intervals. This consequentially caused very large data files, and resulted in the program devoted to determining the elongation times to be computationally intensive. To make this program more efficient, we wrote a Python program to fit a cubic spline to data generated with a 6-minute time step. This resulted in elongation times that were found to agree with those determined from the 5 second data currently used in a large number of cases and was tested for 16 satellites between 2017 and 2019. The accuracy of this program is being tested for the years past 2019 and, if no problems are found, the code will be considered for production of this section of The Astronomical Almanac.

Gravimorphism in rice and barley: promotion of leaf elongation by vertical inversion in agravitropically growing plants.

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Abe, K; Takahashi, H; Suge, H

1998-12-01

We have compared shoot responses of agravitropic rice and barley plants to vertical inversion with those of normal ones. When rice plants were vertically inverted, the main stems of a japonica type of rice, cv. Kamenoo, showed negative gravitropism at nodes 2-15 of both elongated and non-elongated internodes. However, shoots of lazy line of rice, lazy-Kamenoo, bent gravitropically at nodes 11-15 only elongated internodes but not at nodes 2-10 of non-elongated ones. Thus, shoots of Kamenoo responded gravitropically at all stages of growth, whereas shoots of lazy-Kamenoo did not show gravitropic response before heading. In Kamenoo plants, lengths of both leaf-sheath and leaf-blade were shortened by vertical inversion, but those of the vertically inverted plants of lazy-Kamenoo were significantly longer than the plants in an upright position. When agravitropic and normal plants of barley were vertically inverted, the same results as in rice were obtained; elongation of both leaf-sheath and leaf-blade was inhibited in normal barley plants, Chikurin-Ibaragi No. 1, but significantly stimulated in agravitropic plants of serpentina barley. These results suggest that vertical inversion of rice and barley plants enhances the elongation growth of leaves in the absence of tropistic response.

Sperm Impairment by Sperm Agglutinating Factor Isolated from Escherichia coli: Receptor Specific Interactions

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Kiranjeet Kaur

2013-01-01

Full Text Available In an earlier work done in our laboratory, we have been able to isolate a sperm agglutinating strain of Escherichia coli from the semen sample of a male attending infertility clinic. Further, factor responsible for sperm agglutination (SAF was isolated and purified, and, using SAF as a tool, corresponding SAF binding receptor from human spermatozoa has been purified. Characterization of SAF and SAF binding receptor using MALDI-TOF showed homology to glutamate decarboxylase and MHC class I molecule, respectively. Coincubation of SAF with spermatozoa not only resulted in spermagglutination but could also compromise other sperm parameters, namely, Mg2+ dependent ATPase activity and apoptosis. Intravaginal administration of SAF could lead to infertility in Balb/c mice. SAF induced impairment of sperm parameters, and infertility was observed to be due to interaction of SAF with sperm surface receptor component as, when purified receptor was introduced, receptor completely inhibited all the detrimental effects induced by SAF. From these results, it could be concluded that interaction of SAF with spermatozoa is receptor mediated.

Deficiency in l-Serine Deaminase Interferes with One-Carbon Metabolism and Cell Wall Synthesis in Escherichia coli K-12▿

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Zhang, Xiao; El-Hajj, Ziad W.; Newman, Elaine

2010-01-01

Escherichia coli K-12 provided with glucose and a mixture of amino acids depletes l-serine more quickly than any other amino acid even in the presence of ammonium sulfate. A mutant without three 4Fe4S l-serine deaminases (SdaA, SdaB, and TdcG) of E. coli K-12 is unable to do this. The high level of l-serine that accumulates when such a mutant is exposed to amino acid mixtures starves the cells for C1 units and interferes with cell wall synthesis. We suggest that at high concentrations, l-serine decreases synthesis of UDP-N-acetylmuramate-l-alanine by the murC-encoded ligase, weakening the cell wall and producing misshapen cells and lysis. The inhibition by high l-serine is overcome in several ways: by a large concentration of l-alanine, by overproducing MurC together with a low concentration of l-alanine, and by overproducing FtsW, thus promoting septal assembly and also by overexpression of the glycine cleavage operon. S-Adenosylmethionine reduces lysis and allows an extensive increase in biomass without improving cell division. This suggests that E. coli has a metabolic trigger for cell division. Without that reaction, if no other inhibition occurs, other metabolic functions can continue and cells can elongate and replicate their DNA, reaching at least 180 times their usual length, but cannot divide. PMID:20729359

Effects of rare earth oxide nanoparticles on root elongation of plants.

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Ma, Yuhui; Kuang, Linglin; He, Xiao; Bai, Wei; Ding, Yayun; Zhang, Zhiyong; Zhao, Yuliang; Chai, Zhifang

2010-01-01

The phytotoxicity of four rare earth oxide nanoparticles, nano-CeO(2), nano-La(2)O(3), nano-Gd(2)O(3) and nano-Yb(2)O(3) on seven higher plant species (radish, rape, tomato, lettuce, wheat, cabbage, and cucumber) were investigated in the present study by means of root elongation experiments. Their effects on root growth varied greatly between different nanoparticles and plant species. A suspension of 2000 mg L(-1) nano-CeO(2) had no effect on the root elongation of six plants, except lettuce. On the contrary, 2000 mg L(-1) suspensions of nano-La(2)O(3), nano-Gd(2)O(3) and nano-Yb(2)O(3) severely inhibited the root elongation of all the seven species. Inhibitory effects of nano-La(2)O(3), nano-Gd(2)O(3), and nano-Yb(2)O(3) also differed in the different growth process of plants. For wheat, the inhibition mainly took place during the seed incubation process, while lettuce and rape were inhibited on both seed soaking and incubation process. The fifty percent inhibitory concentrations (IC(50)) for rape were about 40 mg L(-1) of nano-La(2)O(3), 20mg L(-1) of nano-Gd(2)O(3), and 70 mg L(-1) of nano-Yb(2)O(3), respectively. In the concentration ranges used in this study, the RE(3+) ion released from the nanoparticles had negligible effects on the root elongation. These results are helpful in understanding phytotoxicity of rare earth oxide nanoparticles. Copyright 2009 Elsevier Ltd. All rights reserved.

Comparative Genomics and Characterization of Hybrid Shigatoxigenic and Enterotoxigenic Escherichia coli (STEC/ETEC) Strains.

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Nyholm, Outi; Halkilahti, Jani; Wiklund, Gudrun; Okeke, Uche; Paulin, Lars; Auvinen, Petri; Haukka, Kaisa; Siitonen, Anja

2015-01-01

Shigatoxigenic Escherichia coli (STEC) and enterotoxigenic E. coli (ETEC) cause serious foodborne infections in humans. These two pathogroups are defined based on the pathogroup-associated virulence genes: stx encoding Shiga toxin (Stx) for STEC and elt encoding heat-labile and/or est encoding heat-stable enterotoxin (ST) for ETEC. The study investigated the genomics of STEC/ETEC hybrid strains to determine their phylogenetic position among E. coli and to define the virulence genes they harbor. The whole genomes of three STEC/ETEC strains possessing both stx and est genes were sequenced using PacBio RS sequencer. Two of the strains were isolated from the patients, one with hemolytic uremic syndrome, and one with diarrhea. The third strain was of bovine origin. Core genome analysis of the shared chromosomal genes and comparison with E. coli and Shigella spp. reference genomes was performed to determine the phylogenetic position of the STEC/ETEC strains. In addition, a set of virulence genes and ETEC colonization factors were extracted from the genomes. The production of Stx and ST were studied. The human STEC/ETEC strains clustered with strains representing ETEC, STEC, enteroaggregative E. coli, and commensal and laboratory-adapted E. coli. However, the bovine STEC/ETEC strain formed a remote cluster with two STECs of bovine origin. All three STEC/ETEC strains harbored several other virulence genes, apart from stx and est, and lacked ETEC colonization factors. Two STEC/ETEC strains produced both toxins and one strain Stx only. This study shows that pathogroup-associated virulence genes of different E. coli can co-exist in strains originating from different phylogenetic lineages. The possibility of virulence genes to be associated with several E. coli pathogroups should be taken into account in strain typing and in epidemiological surveillance. Development of novel hybrid E. coli strains may cause a new public health risk, which challenges the traditional diagnostics

Comparative Genomics and Characterization of Hybrid Shigatoxigenic and Enterotoxigenic Escherichia coli (STEC/ETEC Strains.

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Outi Nyholm

Full Text Available Shigatoxigenic Escherichia coli (STEC and enterotoxigenic E. coli (ETEC cause serious foodborne infections in humans. These two pathogroups are defined based on the pathogroup-associated virulence genes: stx encoding Shiga toxin (Stx for STEC and elt encoding heat-labile and/or est encoding heat-stable enterotoxin (ST for ETEC. The study investigated the genomics of STEC/ETEC hybrid strains to determine their phylogenetic position among E. coli and to define the virulence genes they harbor.The whole genomes of three STEC/ETEC strains possessing both stx and est genes were sequenced using PacBio RS sequencer. Two of the strains were isolated from the patients, one with hemolytic uremic syndrome, and one with diarrhea. The third strain was of bovine origin. Core genome analysis of the shared chromosomal genes and comparison with E. coli and Shigella spp. reference genomes was performed to determine the phylogenetic position of the STEC/ETEC strains. In addition, a set of virulence genes and ETEC colonization factors were extracted from the genomes. The production of Stx and ST were studied.The human STEC/ETEC strains clustered with strains representing ETEC, STEC, enteroaggregative E. coli, and commensal and laboratory-adapted E. coli. However, the bovine STEC/ETEC strain formed a remote cluster with two STECs of bovine origin. All three STEC/ETEC strains harbored several other virulence genes, apart from stx and est, and lacked ETEC colonization factors. Two STEC/ETEC strains produced both toxins and one strain Stx only.This study shows that pathogroup-associated virulence genes of different E. coli can co-exist in strains originating from different phylogenetic lineages. The possibility of virulence genes to be associated with several E. coli pathogroups should be taken into account in strain typing and in epidemiological surveillance. Development of novel hybrid E. coli strains may cause a new public health risk, which challenges the

Chain elongation and cyclization in type III PKS DpgA.

Science.gov (United States)

Wu, Hai-Chen; Li, Yi-San; Liu, Yu-Chen; Lyu, Syue-Yi; Wu, Chang-Jer; Li, Tsung-Lin

2012-04-16

Chain elongation and cyclization of precursors of dihydroxyphenylacetyl-CoA (DPA-CoA) catalyzed by the bacterial type III polyketide synthase DpgA were studied. Two labile intermediates, di- and tri-ketidyl-CoA (DK- and TK-CoA), were proposed and chemically synthesized. In the presence of DpgABD, each of these with [(13)C(3)]malonyl-CoA (MA-CoA) was able to form partially (13)C-enriched DPA-CoA. By NMR and MS analysis, the distribution of (13)C atoms in the partially (13)C-enriched DPA-CoA shed light on how the polyketide chain elongates and cyclizes in the DpgA-catalyzed reaction. Polyketone intermediates elongate in a manner different from that which had been believed: two molecules of DK-CoA, or one DK-CoA plus one acetoacetyl-CoA (AA-CoA), but not two molecules of AA-CoA can form one molecule of DPA-CoA. As a result, polyketidyl-CoA serves as both the starter and extender, whereas polyketone-CoA without the terminal carboxyl group can only act as an extender. The terminal carboxyl group is crucial for the cyclization that likely takes place on CoA. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Promoting chain elongation in mixed culture acidification reactors by addition of ethanol

International Nuclear Information System (INIS)

Grootscholten, T.I.M.; Kinsky dal Borgo, F.; Hamelers, H.V.M.; Buisman, C.J.N.

2013-01-01

In this research we investigate a microbial production process to produce medium chain fatty acids (MCFAs) based on the organic fraction of municipal solid waste (OFMSW). In this microbial production process, called chain elongation, bacteria produce medium chain fatty acids (MCFAs) from ethanol and volatile fatty acids (VFAs). MCFAs could be used as new biomass based building blocks for the chemical and fuel industry. The objective of this article is to investigate whether chain elongation can be promoted during acidification of OFMSW by addition of ethanol. The results show that chain elongation can be promoted during acidification of OFMSW by addition of ethanol. However, the hydrolysis rate and the carboxylic acid yield of the OFMSW in reactors with ethanol additions were lower than the hydrolysis rate and the carboxylic acid yield than in reactors without ethanol additions. Further research is required to determine whether a combined chain elongation and acidification reactor or a separated reactor system is more advantageous for MCFA production from OFMSW. -- Highlights: ► Production of medium chain fatty acids from municipal solid waste and ethanol. ► Insight in production of caproate and consumption of in-situ produced ethanol. ► Ethanol additions reduced propionate, butyrate and valerate concentrations. ► Ethanol additions hardly reduced acetate concentrations. ► Hydrolysis rate was lower in experiments with ethanol additions

Abscisic Acid Regulates Auxin Homeostasis in Rice Root Tips to Promote Root Hair Elongation

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Tao Wang

2017-06-01

Full Text Available Abscisic acid (ABA plays an essential role in root hair elongation in plants, but the regulatory mechanism remains to be elucidated. In this study, we found that exogenous ABA can promote rice root hair elongation. Transgenic rice overexpressing SAPK10 (Stress/ABA-activated protein kinase 10 had longer root hairs; rice plants overexpressing OsABIL2 (OsABI-Like 2 had attenuated ABA signaling and shorter root hairs, suggesting that the effect of ABA on root hair elongation depends on the conserved PYR/PP2C/SnRK2 ABA signaling module. Treatment of the DR5-GUS and OsPIN-GUS lines with ABA and an auxin efflux inhibitor showed that ABA-induced root hair elongation depends on polar auxin transport. To examine the transcriptional response to ABA, we divided rice root tips into three regions: short root hair, long root hair and root tip zones; and conducted RNA-seq analysis with or without ABA treatment. Examination of genes involved in auxin transport, biosynthesis and metabolism indicated that ABA promotes auxin biosynthesis and polar auxin transport in the root tip, which may lead to auxin accumulation in the long root hair zone. Our findings shed light on how ABA regulates root hair elongation through crosstalk with auxin biosynthesis and transport to orchestrate plant development.

ANALISIS KANDUNGAN BORAKS DAN Escherichia coli PADA JAJANAN BAKSO SAPI YANG DIPERDAGANGKAN DI KOTA BANJARBARU

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Nur Rahmi

2016-09-01

Full Text Available This study aims to determine how the content of borax and Escherichia coli on meatballs snacks and the factors that affect the food security of meatballs snacks by using Easy Method of Borax Test and Method of Most Probable Number (MPN for Escherichia coli bacteria contamination. This research was conducted in Banjarbaru on 5 villages, and sampling technique used is stratified sampling. The results of the study showed that from 32 samples taken from five village location, it was not identified any borax based on PERMENKES No. 033 of 2012, while for the examination of Escherichia coli, there are 14 samples of meatballs (43.75% which were eligible, and 18 samples of meatballs (56.25% which containEscherichia coli ranges from 3.6 to 62 CFU /g or not meeting the criteria of ISO 7388: 2009. The factor that might not trigger the addition of borax is that the traders have a good knowledge and attitude toward borax which regarded as a toxic substance and can be harmful to health. Factors that cause microbial contamination of Escherichia coli on meatballs snacks is the lack of food hygiene and sanitation in the food processing, cooked food storage, transport, serving, sanitation facilities, and personnel handlers compared with the good supply of foodstuffs and food ingredients storage.

Differential expression of α-L-arabinofuranosidases during maize (Zea mays L.) root elongation.

Science.gov (United States)

Kozlova, Liudmila V; Gorshkov, Oleg V; Mokshina, Natalia E; Gorshkova, Tatyana A

2015-05-01

Specific α- l -arabinofuranosidases are involved in the realisation of elongation growth process in cells with type II cell walls. Elongation growth in a plant cell is largely based on modification of the cell wall. In type II cell walls, the Ara/Xyl ratio is known to decrease during elongation due to the partial removal of Ara residues from glucuronoarabinoxylan. We searched within the maize genome for the genes of all predicted α-L-arabinofuranosidases that may be responsible for such a process and related their expression to the activity of the enzyme and the amount of free arabinose measured in six zones of a growing maize root. Eight genes of the GH51 family (ZmaABFs) and one gene of the GH3 family (ZmaARA-I) were identified. The abundance of ZmaABF1 and 3-6 transcripts was highly correlated with the measured enzymatic activity and free arabinose content that significantly increased during elongation. The transcript abundances also coincided with the pattern of changes in the Ara/Xyl ratio of the xylanase-extractable glucuronoarabinoxylan described in previous studies. The expression of ZmaABF3, 5 and 6 was especially up-regulated during elongation although corresponding proteins are devoid of the catalytic glutamate at the proper position. ZmaABF2 transcripts were specifically enriched in the root cap and meristem. A single ZmaARA-I gene was not expressed as a whole gene but instead as splice variants that encode the C-terminal end of the protein. Changes in the ZmaARA-I transcript level were rather moderate and had no significant correlation with free arabinose content. Thus, elongation growth of cells with type II cell walls is accompanied by the up-regulation of specific and predicted α-L-arabinofuranosidase genes, and the corresponding activity is indeed pronounced and is important for the modification of glucuronoarabinoxylan, which plays a key role in the modification of the cell wall supramolecular organisation.

High-level expression of human stem cell factor fused with erythropoietin mimetic peptide in Escherichia coli.

Science.gov (United States)

Su, Lin; Chen, Song-Sen; Yang, Ke-Gong; Liu, Chang-Zheng; Zhang, Yan-Li; Liang, Zhi-Quan

2006-06-01

Stem cell factor (SCF) and erythropoietin are essential for normal erythropoiesis and induce proliferation and differentiation synergistically for erythroid progenitor cells. Here, we report our work on construction of SCF/erythropoietin mimetic peptide (EMP) fusion protein gene, in which human SCF cDNA (1-165aa) and EMP sequence (20aa) were connected using a short (GGGGS) or long (GGGGSGGGGGS) linker sequence. The SCF/EMP gene was cloned into the pBV220 vector and expressed in the Escherichia coli DH5alpha strain. The expression level of the fusion protein was about 30% of total cell protein. The resulting inclusion bodies were solubilized with 8 M urea, followed by dilution refolding. The renatured protein was subsequently purified by Q-Sepharose FF column. The final product was >95% pure by SDS-PAGE and the yield of fusion protein was about 40 mg/L of culture. UT-7 cell proliferation and human cord blood cell colony-forming assays showed that the fusion proteins exhibited more potent activity than recombinant human SCF, suggesting a new strategy to enhance biological activities of growth factors.

Fluoroquinolone-Resistant Escherichia coli Infections after Transrectal Biopsy of the Prostate in the Veterans Affairs Healthcare System

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Elie Antoun Saade

2016-09-01

Full Text Available Background: Recent reports suggest that infections due to fluoroquinolone-resistant Escherichia coli (E. coli are an increasingly common complication of transrectal biopsy of the prostate (TBP in the United States. A better understanding of the magnitude and scope of these infections is needed to guide prevention efforts. Our objective is to determine whether the incidence of infections due to fluoroquinolone-resistant E. coli after TBP has increased nationwide in the Veterans Affairs Health Care System and to identify risk factors for infection. Methods: We performed a retrospective, observational cohort study and a nested case-control study within the US Deparment of Veterans Affairs Healthcare System. The primary outcomes were the incidence of urinary tract infection (UTI and bacteremia with E. coli and with fluoroquinolone-resistant E. coli strains within 30 days after TBP. Secondary endpoints focused on the correlation between fluoroquinolone-resistance in all urinary E. coli isolates and post-TBP infection and risk factors for infection due to fluoroquinolone-resistant E. coli infection. Results: 245 618 patients undergoing 302 168 TBP procedures from 2000 through 2013 were included in the cohort study, and 59 469 patients undergoing TBP from 2011 through 2013 were included in the nested case-control study. Between 2000 and 2013, there was a 5-fold increase in the incidence of E. coli UTI (0.18%–0.93% and a 4-fold increase in the incidence of E. coli bacteremia (0.04%–0.18% after TBP that was attributable to an increase in the incidence of fluoroquinolone-resistant E. coli UTI (0.03%–0.75% and bacteremia (0.01%–0.14%. The increasing incidence of fluoroquinolone-resistant E. coli infections after TBP occurred in parallel with increasing rates of fluoroquinolone-resistance in all urinary E. coli isolates. By multivariable logistic regression analysis, independent risk factors for fluoroquinolone

Reduction of verotoxigenic Escherichia coli in production of fermented sausages.

Science.gov (United States)

Holck, Askild L; Axelsson, Lars; Rode, Tone Mari; Høy, Martin; Måge, Ingrid; Alvseike, Ole; L'abée-Lund, Trine M; Omer, Mohamed K; Granum, Per Einar; Heir, Even

2011-11-01

After a number of foodborne outbreaks of verotoxigenic Escherichia coli involving fermented sausages, some countries have imposed regulations on sausage production. For example, the US Food Safety and Inspection Service requires a 5 log(10) reduction of E. coli in fermented products. Such regulations have led to a number of studies on the inactivation of E. coli in fermented sausages by changing processing and post-processing conditions. Several factors influence the survival of E. coli such as pre-treatment of the meat, amount of NaCl, nitrite and lactic acid, water activity, pH, choice of starter cultures and addition of antimicrobial compounds. Also process variables like fermentation temperature and storage time play important roles. Though a large variety of different production processes of sausages exist, generally the reduction of E. coli caused by production is in the range 1-2 log(10). In many cases this may not be enough to ensure microbial food safety. By optimising ingredients and process parameters it is possible to increase E. coli reduction to some extent, but in some cases still other post process treatments may be required. Such treatments may be storage at ambient temperatures, specific heat treatments, high pressure processing or irradiation. HACCP analyses have identified the quality of the raw materials, low temperature in the batter when preparing the sausages and a rapid pH drop during fermentation as critical control points in sausage production. This review summarises the literature on the reduction verotoxigenic E. coli in production of fermented sausages. Copyright © 2011 Elsevier Ltd. All rights reserved.

Mapping Sites of O-Glycosylation and Fringe Elongation on Drosophila Notch*

Science.gov (United States)

Harvey, Beth M.; Rana, Nadia A.; Moss, Hillary; Leonardi, Jessica; Jafar-Nejad, Hamed; Haltiwanger, Robert S.

2016-01-01

Glycosylation of the Notch receptor is essential for its activity and serves as an important modulator of signaling. Three major forms of O-glycosylation are predicted to occur at consensus sites within the epidermal growth factor-like repeats in the extracellular domain of the receptor: O-fucosylation, O-glucosylation, and O-GlcNAcylation. We have performed comprehensive mass spectral analyses of these three types of O-glycosylation on Drosophila Notch produced in S2 cells and identified peptides containing all 22 predicted O-fucose sites, all 18 predicted O-glucose sites, and all 18 putative O-GlcNAc sites. Using semiquantitative mass spectral methods, we have evaluated the occupancy and relative amounts of glycans at each site. The majority of the O-fucose sites were modified to high stoichiometries. Upon expression of the β3-N-acetylglucosaminyltransferase Fringe with Notch, we observed varying degrees of elongation beyond O-fucose monosaccharide, indicating that Fringe preferentially modifies certain sites more than others. Rumi modified O-glucose sites to high stoichiometries, although elongation of the O-glucose was site-specific. Although the current putative consensus sequence for O-GlcNAcylation predicts 18 O-GlcNAc sites on Notch, we only observed apparent O-GlcNAc modification at five sites. In addition, we performed mass spectral analysis on endogenous Notch purified from Drosophila embryos and found that the glycosylation states were similar to those found on Notch from S2 cells. These data provide foundational information for future studies investigating the mechanisms of how O-glycosylation regulates Notch activity. PMID:27268051

Epimerization-free C-terminal peptide activation, elongation and cyclization

NARCIS (Netherlands)

Popović, S.

2015-01-01

C-terminal peptide activation and cyclization reactions are generally accompanied with epimerization (partial loss of C‐terminal stereointegrity). Therefore, the focus of this thesis was to develop epimerization-free methods for C-terminal peptide activation to enable C-terminal peptide elongation

Influence of some bacterial and host factors on colonization and invasiveness of Escherichia coli K1 in neonatal rats.

OpenAIRE

Wullenweber, M; Beutin, L; Zimmermann, S; Jonas, C

1993-01-01

Of 209 healthy infants examined, 44 (21.1%) carried Escherichia coli K1 in their feces. Of these 44 isolates, 36 (81.8%) were attributed to 10 different known clonal groups of E. coli K1 and 4 isolates represented unknown types. The influence of mannose-resistant (MR) adhesins, aerobactin production, and resistance to serum on colonization and invasiveness of E. coli K1 in orally infected inbred LEW baby rats was investigated. Strains expressing MR adhesins had significantly higher colonizati...

Pathogenic Escherichia coli producing Extended-Spectrum β-Lactamases isolated from surface water and wastewater.

Science.gov (United States)

Franz, Eelco; Veenman, Christiaan; van Hoek, Angela H A M; de Roda Husman, Ana; Blaak, Hetty

2015-09-24

To assess public health risks from environmental exposure to Extended-Spectrum β-Lactamases (ESBL)-producing bacteria, it is necessary to have insight in the proportion of relative harmless commensal variants and potentially pathogenic ones (which may directly cause disease). In the current study, 170 ESBL-producing E. coli from Dutch wastewater (n = 82) and surface water (n = 88) were characterized with respect to ESBL-genotype, phylogenetic group, resistance phenotype and virulence markers associated with enteroaggregative E. coli (EAEC), enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), extraintesinal E. coli (ExPEC), and Shiga toxin-producing E. coli (STEC). Overall, 17.1% of all ESBL-producing E. coli were suspected pathogenic variants. Suspected ExPECs constituted 8.8% of all ESBL-producing variants and 8.3% were potential gastrointestinal pathogens (4.1% EAEC, 1.8% EPEC, 1.2% EIEC, 1.2% ETEC, no STEC). Suspected pathogens were significantly associated with ESBL-genotype CTX-M-15 (X(2) = 14.7, P antibiotics. In conclusion, this study demonstrates that the aquatic environment is a potential reservoir of E. coli variants that combine ESBL-genes, a high level of multi-drug resistance and virulence factors, and therewith pose a health risk to humans upon exposure.

Heterologous expression of Homo sapiens alpha-folate receptors in E. coli by fusion with a trigger factor for enhanced solubilization.

Science.gov (United States)

Miranda, Beatriz Nogueira Messias; Fotoran, Wesley Luzetti; Canduri, Fernanda; Souza, Dulce Helena Ferreira; Wunderlich, Gerhard; Carrilho, Emanuel

2018-02-01

The role of Alpha folate receptors (FRα) in folate metabolism and cancer development has been extensively studied. The reason for this is not only associated to its direct relation to disease development but also to its potential use as a highly sensitive and specific biomarker for cancers therapies. Over the recent years, the crystal structures of human FRα complexed with different ligands were described relying on an expensive and time-consuming production process. Here, we constructed an efficient system for the expression and purification of a human FRα in E. coli. Unlike a conventional expression method we used a specific protein fusion expressing the target protein together with a trigger factor (TF). This factor is a chaperone from E. coli that assists the correct folding of newly synthesized polypeptide chains. The activity of rTFFRα was comparable to glycosylphosphatidylinositol (GPI) anchored proteins extracted from HeLa tumor cells. Our work demonstrates a straightforward and versatile approach for the production of active human FRα by heterologous expression; this approach further enhances the development of inhibition studies and biotechnological applications. The purified product was then conjugated to liposomes, obtaining a 35% higher signal from densitometry measurement on the immunoblotting assay in the contruct containing the Ni-NTA tag, as a mimesis of an exosome, which is of vital importance to nanotherapeutic techniques associated to treatment and diagnosis of tumors. Copyright © 2017 Elsevier Inc. All rights reserved.

Adiabatic compression of elongated field-reversed configurations

Energy Technology Data Exchange (ETDEWEB)

Spencer, R.L.; Tuszewski, M.; Linford, R.K.

1983-06-01

The adiabatic compression of an elongated field-reversed configuration (FRC) is computed by using a one-dimensional approximation. The one-dimensional results are checked against a two-dimensional equilibrium code. For ratios of FRC separatrix length to separatrix radius greater than about ten, the one-dimensional results are accurate within 10%. To this accuracy, the adiabatic compression of FRC's can be described by simple analytic formulas.

Modeling the growth dynamics of multiple Escherichia coli strains in the pig intestine following intramuscular ampicillin treatment

DEFF Research Database (Denmark)

Ahmad, Amais; Zachariasen, Camilla; Christiansen, Lasse Engbo

2016-01-01

using a mathematical model to simulate the competitive growth of E. coli strains in a pig intestine under specified plasma concentration profiles of ampicillin. Results : In vitro growth results demonstrated that the resistant strains did not carry a fitness cost for their resistance, and that the most...... with ampicillin resistance in E. coli. Besides dosing factors, epidemiological factors (such as number of competing strains and bacterial excretion) influenced resistance development and need to be considered further in relation to optimal treatment strategies. The modeling approach used in the study is generic......Background : This study evaluated how dosing regimen for intramuscularly-administered ampicillin, composition of Escherichia coli strains with regard to ampicillin susceptibility, and excretion of bacteria from the intestine affected the level of resistance among Escherichia coli strains...

Escherichia coli in broiler chickens with airsacculitis

Directory of Open Access Journals (Sweden)

Leandro S. Machado

2014-09-01

Full Text Available ABSTRACT. Machado L.S., do Nascimento E.R., Pereira V.L.A., Abreu D.L.C., Gouvea R. & Santos L.M.M. 2014. [Escherichia coli in broiler chickens with airsacculitis.] Escherichia coli em frangos de corte com aerossaculite. Revista Brasileira de Medicina Veterinária, 36(3:261-265, 2014. Departamento de Medicina Veterinária Preventiva e Saúde Pública, Faculdade de Veterinária, Universidade Federal Fluminense, Rua Dr. Vital Brazil Filho 64, Vital Brazil, Niterói, RJ 24230-340, Brazil. E-mail: leandromachadovet@yahoo.com.br The Brazilian poultry industry grows each year and becomes increasingly representative in the production and export of products. The health care with poultry have accompanied and favored this evolution, however, respiratory agents that affect the weight and carcass quality, continue to cause great damage to the poultry industry. Airsacculitis is considered the main cause of total and partial condemnation of carcasses of broilers, and has been attributed to Mycoplasmosis mostly caused by Mycoplasma gallisepticum (MG and Mycoplasma synoviae (MS and Escherichia coli. The aim of this study was to relate the positivity of MG / MS and E. coli detected by PCR as a risk factor for airsacculitis in condemnation of broilers in Health Inspection Service. We studied 30 broiler poultry slaughtered in a slaughterhouse under Federal Sanitary Inspection, located in the State of Rio de Janeiro. 30 chickens were randomly collected from different lots and tracheas obtained in each PCR. DNA was extracted by phenol-chloroform method and amplified using pairs of “primer”specific for MG, MS and E. coli. Of the 30 chickens analyzed by PCR, 30% (9/30 had lesions in air sacs. None of the birds showed infection with MG and/or MS PCR, however 33.3% (3/9 birds were positive for airsacculitis iss gene from E.coli. E.coli found in broiler chickens that were negative for mycoplasma airsacculitis, implying the presence of such bacteria may be sufficient

Telomere Elongation and Naive Pluripotent Stem Cells Achieved from Telomerase Haplo-Insufficient Cells by Somatic Cell Nuclear Transfer

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Li-Ying Sung

2014-12-01

Full Text Available Summary: Haplo-insufficiency of telomerase genes in humans leads to telomere syndromes such as dyskeratosis congenital and idiopathic pulmonary fibrosis. Generation of pluripotent stem cells from telomerase haplo-insufficient donor cells would provide unique opportunities toward the realization of patient-specific stem cell therapies. Recently, pluripotent human embryonic stem cells (ntESCs have been efficiently achieved by somatic cell nuclear transfer (SCNT. We tested the hypothesis that SCNT could effectively elongate shortening telomeres of telomerase haplo-insufficient cells in the ntESCs with relevant mouse models. Indeed, telomeres of telomerase haplo-insufficient (Terc+/− mouse cells are elongated in ntESCs. Moreover, ntESCs derived from Terc+/− cells exhibit naive pluripotency as evidenced by generation of Terc+/− ntESC clone pups by tetraploid embryo complementation, the most stringent test of naive pluripotency. These data suggest that SCNT could offer a powerful tool to reprogram telomeres and to discover the factors for robust restoration of telomeres and pluripotency of telomerase haplo-insufficient somatic cells. : Sung et al. demonstrate in a mouse model that telomeres of telomerase haplo-insufficient cells can be elongated by somatic cell nuclear transfer. Moreover, ntESCs derived from Terc+/− cells exhibit pluripotency evidenced by generation of Terc+/−ntESC clone pups by tetraploid embryo complementation, the most stringent test of naive pluripotency.

The relationship between the types of axial elongation and the prevalence of lattice degeneration of the retina.

Science.gov (United States)

Yura, T

1998-02-01

To assess the relationship between the prevalence of lattice degeneration and the types of axial elongation. Nine hundred seventy eyes of 542 highly myopic patients with axial length of 26.00-31.99 mm were evaluated by using A-scan axial length measurements and fundus examinations. Then the prevalence of lattice degeneration was compared between eyes with posterior staphyloma and those without posterior staphyloma. At each axial length, lattice degeneration was more frequent in eyes without posterior staphyloma (the entire eye elongates) than those with posterior staphyloma (only the posterior pole elongates). The difference was statistically significant (plattice degeneration is influenced by the types of axial elongation in high myopic eyes.

ROS mediated selection for increased NADPH availability in Escherichia coli.

Science.gov (United States)

Reynolds, Thomas S; Courtney, Colleen M; Erickson, Keesha E; Wolfe, Lisa M; Chatterjee, Anushree; Nagpal, Prashant; Gill, Ryan T

2017-11-01

The economical production of chemicals and fuels by microbial processes remains an intense area of interest in biotechnology. A key limitation in such efforts concerns the availability of key co-factors, in this case NADPH, required for target pathways. Many of the strategies pursued for increasing NADPH availability in Escherichia coli involve manipulations to the central metabolism, which can create redox imbalances and overall growth defects. In this study we used a reactive oxygen species based selection to search for novel methods of increasing NADPH availability. We report a loss of function mutation in the gene hdfR appears to increase NADPH availability in E. coli. Additionally, we show this excess NADPH can be used to improve the production of 3HP in E. coli. © 2017 Wiley Periodicals, Inc.

Annual Surveillance Summary: Escherichia coli (E. coli) Infections in the Military Health System (MHS), 2015

Science.gov (United States)

2017-03-01

Annual Surveillance Summary: Escherichia coli ( E . coli ) Infections in the Military Health System (MHS...or position of the Department of the Navy, Department of Defense, nor the U.S. Government. i i E . coli in the MHS: Annual Summary 2015 Prepared...March 2017 EpiData Center Department NMCPHC-EDC-TR-187-2017 ii ii E . coli in the MHS: Annual Summary 2015 Prepared March 2017 EpiData

Enterohemorrhagic Escherichia coli (EHEC

Directory of Open Access Journals (Sweden)

Abdullah Kilic

2011-08-01

Full Text Available Escherichia coli is a bacterium that is commonly found in the gut of humans and warm-blooded animals. Most strains of E. coli are harmless for human. E. coli O157:H7 is the most common member of a group of pathogenic E. coli strains known variously as enterohaemorrhagic, verocytotoxin-producing, or Shiga-toxin-producing organisms. EHEC bacterium is the major cause of haemorrhagic colitis and haemolytic uraemic syndrome. The reservoir of this pathogen appears to be mainly cattle and other ruminants such as camels. It is transmitted to humans primarily through consumption of contaminated foods. [TAF Prev Med Bull 2011; 10(4.000: 387-388

Reproducible gene targeting in recalcitrant Escherichia coli isolates

Directory of Open Access Journals (Sweden)

De Greve Henri

2011-06-01

Full Text Available Abstract Background A number of allele replacement methods can be used to mutate bacterial genes. For instance, the Red recombinase system of phage Lambda has been used very efficiently to inactivate chromosomal genes in E. coli K-12, through recombination between regions of homology. However, this method does not work reproducibly in some clinical E. coli isolates. Findings The procedure was modified by using longer homologous regions (85 bp and 500-600 bp, to inactivate genes in the uropathogenic E. coli strain UTI89. An lrhA regulator mutant, and deletions of the lac operon as well as the complete type 1 fimbrial gene cluster, were obtained reproducibly. The modified method is also functional in other recalcitrant E. coli, like the avian pathogenic E. coli strain APEC1. The lrhA regulator and lac operon deletion mutants of APEC1 were successfully constructed in the same way as the UTI89 mutants. In other avian pathogenic E. coli strains (APEC3E, APEC11A and APEC16A it was very difficult or impossible to construct these mutants, with the original Red recombinase-based method, with a Red recombinase-based method using longer (85 bp homologous regions or with our modified protocol, using 500 - 600 bp homologous regions. Conclusions The method using 500-600 bp homologous regions can be used reliably in some clinical isolates, to delete single genes or entire operons by homologous recombination. However, it does not invariably show a greater efficiency in obtaining mutants, when compared to the original Red-mediated gene targeting method or to the gene targeting method with 85 bp homologous regions. Therefore the length of the homology regions is not the only limiting factor for the construction of mutants in these recalcitrant strains.

Cessation of reproduction-related spine elongation after multiple breeding cycles in female naked mole-rats.

Science.gov (United States)

Dengler-Crish, Christine M; Catania, Kenneth C

2009-01-01

The breeding female or "queen" naked mole-rat has a uniquely elongated body morphology attributed to the lengthening of the lumbar vertebral column that occurs during pregnancy. It is unknown whether this vertebral growth is a continuous process, or associated only with early reproductive experience. We compared pregnancy-related bone elongation in nascent primiparous queens and established queens to determine if this vertebral expansion was a lifelong process in these females. We also investigated the impact of lactation on vertebral elongation in these mole-rats because it is known to be a time of significant bone loss in other mammals. Our data show that after eight or more pregnancies, established queens no longer experienced a net gain in lumbar spine length over the reproductive cycle, whereas the nascent breeders demonstrated significant spine lengthening over this time. Despite the lack of net spine lengthening in established breeders, our results indicated that these queens still experienced some pregnancy-specific vertebral elongation. In naked mole-rats, pregnancy-induced bone elongation may serve the dual purposes of first lengthening the spine, and then once optimal spine size is achieved, serving as a homeostatic mechanism that prepares the spine for the mineral demands of lactation. Anat Rec, 2009. (c) 2008 Wiley-Liss, Inc.

Species differences in ligand specificity of auxin-controlled elongation and auxin transport: comparing Zea and Vigna

Science.gov (United States)

Zhao, Hu; Hertel, Rainer; Ishikawa, Hideo; Evans, Michael L.

2002-01-01

The plant hormone auxin affects cell elongation in both roots and shoots. In roots, the predominant action of auxin is to inhibit cell elongation while in shoots auxin, at normal physiological levels, stimulates elongation. The question of whether the primary receptor for auxin is the same in roots and shoots has not been resolved. In addition to its action on cell elongation in roots and shoots, auxin is transported in a polar fashion in both organs. Although auxin transport is well characterized in both roots and shoots, there is relatively little information on the connection, if any, between auxin transport and its action on elongation. In particular, it is not clear whether the protein mediating polar auxin movement is separate from the protein mediating auxin action on cell elongation or whether these two processes might be mediated by one and the same receptor. We examined the identity of the auxin growth receptor in roots and shoots by comparing the response of roots and shoots of the grass Zea mays L. and the legume Vigna mungo L. to indole-3-acetic acid, 2-naphthoxyacetic acid, 4,6-dichloroindoleacetic acid, and 4,7-dichloroindoleacetic acid. We also studied whether or not a single protein might mediate both auxin transport and auxin action by comparing the polar transport of indole-3-acetic acid and 2-naphthoxyacetic acid through segments from Vigna hypocotyls and maize coleoptiles. For all of the assays performed (root elongation, shoot elongation, and polar transport) the action and transport of the auxin derivatives was much greater in the dicots than in the grass species. The preservation of ligand specificity between roots and shoots and the parallels in ligand specificity between auxin transport and auxin action on growth are consistent with the hypothesis that the auxin receptor is the same in roots and shoots and that this protein may mediate auxin efflux as well as auxin action in both organ types.

Prevalence and potential risk factors for the occurrence of cefotaxime resistant Escherichia coli in German fattening pig farms--a cross-sectional study.

Science.gov (United States)

Hering, Johanna; Hille, Katja; Frömke, Cornelia; von Münchhausen, Christiane; Hartmann, Maria; Schneider, Bettina; Friese, Anika; Roesler, Uwe; Merle, Roswitha; Kreienbrock, Lothar

2014-09-01

A cross-sectional study concerning farm prevalence and risk factors for the count of cefotaxime resistant Escherichia coli (E. coli) (CREC) positive samples per sampling group on German fattening pig farms was performed in 2011 and 2012. Altogether 48 farms in four agricultural regions in the whole of Germany were investigated. Faecal samples, boot swabs and dust samples from two sampling groups per farm were taken and supplemental data were collected using a questionnaire. On 85% of the farms, at least one sample contained cefotaxime resistant E. coli colonies. Positive samples were more frequent in faeces (61%) and boot swabs (54%) than in dust samples (11%). Relevant variables from the questionnaire were analysed in a univariable mixed effect Poisson regression model. Variables that were related to the number (risk) of positive samples per sampling group with a p-value risk for positive samples involved farm management and hygienic aspects. Farms that had a separate pen for diseased pigs had a 2.8 higher mean count of positive samples (95%-CI [1.71; 4.58], p=0.001) than farms without an extra pen. The mean count was increased on farms with under-floor exhaust ventilation compared to farms with over floor ventilation (2.22 [1.43; 3.46], p=0.001) and more positive samples were observed on farms that controlled flies with toxin compared to farms that did not (1.86 [1.24; 2.78], p=0.003). It can be concluded, that CREC are wide spread on German fattening pig farms. In addition the explorative approach of the present study suggests an influence of management strategies on the occurrence of cefotaxime resistant E. coli. Copyright © 2014 Elsevier B.V. All rights reserved.

Impact of dry chilling on the genetic diversity of Escherichia coli on beef carcasses and on the survival of E. coli and E. coli O157.

Science.gov (United States)

Visvalingam, Jeyachchandran; Liu, Yang; Yang, Xianqin

2017-03-06

The objective of this study was to examine the effect of dry chilling on the genetic diversity of naturally occurring Escherichia coli on beef carcasses, and to examine whether two populations of E. coli recovered from carcasses during chilling and E. coli O157 differed in their response to desiccation. Isolates of E. coli were obtained from beef carcasses during a 67h dry chilling process and were genotyped using multiple-locus variable-number tandem-repeat analysis (MLVA). Ten E. coli genotypes found only at 0h (group A) and found more than once (group B), as well as five strains of E. coli O157 (group C) were inoculated on stainless steel coupons and their survival was examined after exposure to 75 and 100% relative humidity (RH) at 0 or 35°C for 67h. A total of 450 E. coli isolates were obtained, with 254, 49, 49, 51, 23, 20, and 4 from 0, 1, 2, 4, 6, 8 and 24h of chilling, respectively. No E. coli were recovered at 67h. MLVA of the isolates revealed 173 distinct genotypes. Genetic diversity of E. coli isolates, defined as ratio of the number of isolates to the number of genotypes, remained between 2.3 and 1.3 during the 24h of chilling. All strains inoculated on stainless steel coupons and exposed to 75% RH at 35°C were completely inactivated, irrespective of their groups. Inactivation of E. coli of the three groups was not significantly (P>0.05) different by exposure to 75% RH at 0°C. The findings indicate that the genetic diversity of E. coli on beef carcasses was not affected by dry chilling. In addition, inactivation of E. coli genotypes and E. coli O157 by desiccation on stainless steel simulating dry chilling conditions did not differ significantly (P>0.05). Thus, dry chilling may be used as an effective antimicrobial intervention for beef carcasses. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Characteristics of elongated and ruptured anterior cruciate ligament grafts: An analysis of 21 consecutive revision cases

Directory of Open Access Journals (Sweden)

Kohei Iio

2017-04-01

Conclusion: The location of the original femoral tunnel was more proximal in patients with elongated grafts than in those with ruptured grafts. Different bone tunnel position from native ACL might lead to graft elongation.

Haemolytic Escherichia coli isolated from dogs with diarrhea have characteristics of both uropathogenic and necrotoxigenic strains

NARCIS (Netherlands)

Starxix, M.; Johnson, J.R.; Stell, A.L.; Goot, van der J.A.; Hendriks, H.G.; Vorstenbosch, van C.; Dijk, van L.; Gaastra, W.

2002-01-01

Twenty-four haemolytic Escherichia coli strains were isolated from dogs with diarrhea. The strains were serotyped and analysed by polymerase chain reaction (PCR) for genes encoding virulence factors associated with E. coli that cause diarrhea in animals. Adhesion antigen production was deduced from

Barley Seed Germination/Root Elongation Toxicity Test For Evaluation Of Sludge Pre-Treatment

DEFF Research Database (Denmark)

Eriksson, Eva; Kusk, Kresten Ole; Barrett Sørensen, Mie

Application of sludge from wastewater treatment plants (WWTPs) on agricultural land is an approach for nutrient recycling that rise challenges due to recalcitrant and harmful pollutants. In this study we assessed the feasibility of a seed germination test to evaluate sludge ecotoxicity and compared...... germination responses from two test parameters, root elongation and seed germination (sprouts elongation) of the barley (Hordeum vulgare). 2nd objective was to evaluate sewage sludge pre-treatments at batch-scale of sludge samples from two WWTPs using anaerobic digestion, and thermal and ozonation pre......-treatments. Glyphosate and eco-labelled soil were used as references. Inhibition of germination of seeds exposed to the glyphosate and sludge was registered and thus germination was successfully applied for sludge ecotoxicity assessment, and using the root elongation as the end-point was both faster and more precise...

Prediction of RNA Polymerase II recruitment, elongation and stalling from histone modification data

DEFF Research Database (Denmark)

Chen, Yun; Jørgensen, Mette; Kolde, Raivo

2011-01-01

of RNAPII stalling. CONCLUSIONS: In this study we introduce a general framework to accurately predict the level of RNAPII recruitment, elongation, stalling and mRNA expression from chromatin signals. The versatility of the method also makes it ideally suited to investigate other genomic data....... strategies are needed to progress from descriptive annotation of data to quantitative, predictive models. RESULTS: Here, we describe a computational framework which with high accuracy can predict the locations of core promoters, the amount of recruited RNAPII at the promoter, the amount of elongating RNAPII...... of these four marks are found to be necessary for recruitment of RNAPII but not sufficient for the elongation. We also show that the spatial distributions of histone marks are almost as predictive as the signal strength and that a set of histone marks immediately downstream of the TSS is highly predictive...

The transcription elongation factor ELL2 is specifically upregulated in HTLV-1-infected T-cells and is dependent on the viral oncoprotein Tax.

Science.gov (United States)

Mann, Melanie C; Strobel, Sarah; Fleckenstein, Bernhard; Kress, Andrea K

2014-09-01

The oncoprotein Tax of human T-cell leukemia virus type 1 (HTLV-1) is a potent transactivator of viral and cellular transcription. Here, we identified ELL2 as the sole transcription elongation factor to be specifically upregulated in HTLV-1-/Tax-transformed T-cells. Tax contributes to regulation of ELL2, since transient transfection of Tax increases ELL2 mRNA, Tax transactivates the ELL2 promoter, and repression of Tax results in decrease of ELL2 in transformed T-lymphocytes. However, we also measured upregulation of ELL2 in HTLV-1-transformed cells exhibiting undetectable amounts of Tax, suggesting that ELL2 can still be maintained independent of continuous Tax expression. We further show that Tax and ELL2 synergistically activate the HTLV-1 promoter, indicating that ELL2 cooperates with Tax in viral transactivation. This is supported by our findings that Tax and ELL2 accumulate in nuclear fractions and that they co-precipitate upon co-expression in transiently-transfected cells. Thus, upregulation of ELL2 could contribute to HTLV-1 gene regulation. Copyright © 2014 Elsevier Inc. All rights reserved.

Genome-wide binding site analysis of FAR-RED ELONGATED HYPOCOTYL3 reveals its novel function in Arabidopsis development.

Science.gov (United States)

Ouyang, Xinhao; Li, Jigang; Li, Gang; Li, Bosheng; Chen, Beibei; Shen, Huaishun; Huang, Xi; Mo, Xiaorong; Wan, Xiangyuan; Lin, Rongcheng; Li, Shigui; Wang, Haiyang; Deng, Xing Wang

2011-07-01

FAR-RED ELONGATED HYPOCOTYL3 (FHY3) and its homolog FAR-RED IMPAIRED RESPONSE1 (FAR1), two transposase-derived transcription factors, are key components in phytochrome A signaling and the circadian clock. Here, we use chromatin immunoprecipitation-based sequencing (ChIP-seq) to identify 1559 and 1009 FHY3 direct target genes in darkness (D) and far-red (FR) light conditions, respectively, in the Arabidopsis thaliana genome. FHY3 preferentially binds to promoters through the FHY3/FAR1 binding motif (CACGCGC). Interestingly, FHY3 also binds to two motifs in the 178-bp Arabidopsis centromeric repeats. Comparison between the ChIP-seq and microarray data indicates that FHY3 quickly regulates the expression of 197 and 86 genes in D and FR, respectively. FHY3 also coregulates a number of common target genes with PHYTOCHROME INTERACTING FACTOR 3-LIKE5 and ELONGATED HYPOCOTYL5. Moreover, we uncover a role for FHY3 in controlling chloroplast development by directly activating the expression of ACCUMULATION AND REPLICATION OF CHLOROPLASTS5, whose product is a structural component of the latter stages of chloroplast division in Arabidopsis. Taken together, our data suggest that FHY3 regulates multiple facets of plant development, thus providing insights into its functions beyond light and circadian pathways.

Risk factors and spatial distribution of extended spectrum ?-lactamase-producing- Escherichia coli at retail poultry meat markets in Malaysia: a cross-sectional study

OpenAIRE

Aliyu, A. B.; Saleha, A. A.; Jalila, A.; Zunita, Z.

2016-01-01

Background The significant role of retail poultry meat as an important exposure pathway for the acquisition and transmission of extended spectrum ?-lactamase-producing Escherichia coli (ESBL-EC) into the human population warrants understanding concerning those operational practices associated with dissemination of ESBL-EC in poultry meat retailing. Hence, the objective of this study was to determine the prevalence, spatial distribution and potential risk factors associated with the disseminat...

Characteristics of cytotoxic necrotizing factor and cytolethal distending toxin producing Escherichia coli strains isolated from meat samples in Northern Ireland.

Science.gov (United States)

Kadhum, H J; Ball, H J; Oswald, E; Rowe, M T

2006-08-01

Swabs collected from pig, lamb and beef carcasses and samples of pork, lamb and beef mince were cultured for Escherichia coli strains. Strains harbouring cytotoxic necrotizing factors (CNF1 and 2) and cytolethal distending toxins (CDT-I,-II,-III and -IV) were identified in plate cultures of the isolates by colony hybridization with labelled probes and multiplex PCR assays. Simplex and multiplex PCR assays were used to further characterize the isolates to determine the presence of P, S and F17 fimbriae as well as afimbrial adhesins and haemolysin. The serotype was also determined where possible. Thirty strains with the capacity to code for CNF (4), CDT (24) or both (2) were isolated and characterized, and a wide range of associated factor patterns was observed. The methods utilized were successful in demonstrating the detection of viable strains with potentially significant pathogenic factors from human food sources.

Brassinosteroid regulates cell elongation by modulating gibberellin metabolism in rice.

Science.gov (United States)

Tong, Hongning; Xiao, Yunhua; Liu, Dapu; Gao, Shaopei; Liu, Linchuan; Yin, Yanhai; Jin, Yun; Qian, Qian; Chu, Chengcai

2014-11-01

Brassinosteroid (BR) and gibberellin (GA) are two predominant hormones regulating plant cell elongation. A defect in either of these leads to reduced plant growth and dwarfism. However, their relationship remains unknown in rice (Oryza sativa). Here, we demonstrated that BR regulates cell elongation by modulating GA metabolism in rice. Under physiological conditions, BR promotes GA accumulation by regulating the expression of GA metabolic genes to stimulate cell elongation. BR greatly induces the expression of D18/GA3ox-2, one of the GA biosynthetic genes, leading to increased GA1 levels, the bioactive GA in rice seedlings. Consequently, both d18 and loss-of-function GA-signaling mutants have decreased BR sensitivity. When excessive active BR is applied, the hormone mostly induces GA inactivation through upregulation of the GA inactivation gene GA2ox-3 and also represses BR biosynthesis, resulting in decreased hormone levels and growth inhibition. As a feedback mechanism, GA extensively inhibits BR biosynthesis and the BR response. GA treatment decreases the enlarged leaf angles in plants with enhanced BR biosynthesis or signaling. Our results revealed a previously unknown mechanism underlying BR and GA crosstalk depending on tissues and hormone levels, which greatly advances our understanding of hormone actions in crop plants and appears much different from that in Arabidopsis thaliana. © 2014 American Society of Plant Biologists. All rights reserved.

Actin Cytoskeleton Manipulation by Effector Proteins Secreted by Diarrheagenic Escherichia coli Pathotypes