Articles de revues : « Arcz »

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Zúñiga, Manuel, Marie Champomier-Verges, Monique Zagorec et Gaspar Pérez-Martínez. « Structural and Functional Analysis of the Gene Cluster Encoding the Enzymes of the Arginine Deiminase Pathway ofLactobacillus sake ». Journal of Bacteriology 180, n^o 16 (15 août 1998) : 4154–59. http://dx.doi.org/10.1128/jb.180.16.4154-4159.1998.

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ABSTRACT Lactobacillus sake can use arginine via the arginine deiminase (ADI) pathway. We designed degenerate primers based on an alignment of known sequences of ornithine transcarbamoylase (OTC)-encoding genes in order to amplify the L. sakecounterpart sequences by PCR. Screening a genomic library of L. sake in λEMBL3 allowed us to isolate a clone containing a 10-kbL. sake genomic DNA insert. Sequence analysis revealed that the genes involved in arginine catabolism were clustered and encoded ADI (arcA), OTC (arcB), carbamate kinase (arcC), and a putative carrier with high similarity to the arginine/ornithine antiporter of Pseudomonas aeruginosa(arcD). Additionally, a putative transaminase-encoding gene (arcT) was located in this region. The genes followed the order arcA arcB arcC arcT arcD, which differs from that found in other microorganisms. arcA, arcB,arcC, and arcD mutants were constructed, and the ADI pathway was impaired in all of them. Transcriptional studies indicated that arcA gene is subject to catabolite repression, and under the conditions used, several transcripts could be detected, suggesting the existence of different initiation sites or processing of a larger mRNA.

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Dong, Yiqian, Yi-Ywan M. Chen, Jennifer A. Snyder et R. A. Burne. « Isolation and Molecular Analysis of the Gene Cluster for the Arginine Deiminase System from Streptococcus gordonii DL1 ». Applied and Environmental Microbiology 68, n^o 11 (novembre 2002) : 5549–53. http://dx.doi.org/10.1128/aem.68.11.5549-5553.2002.

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ABSTRACT The arginine deiminase (AD) system (ADS) is one of two major ammonia-generating pathways in the oral cavity that play important roles in oral biofilm pH homeostasis and oral biofilm ecology. To initiate a study of the Streptococcus gordonii ADS, the ADS gene cluster was isolated from subgenomic DNA libraries of S. gordonii DL1 by using an arcB-specific probe. Nucleotide sequence analysis revealed six open reading frames (ORFs) that were arranged contiguously; the first five ORFs were transcribed in the same direction, as an apparent operon, and the sixth was transcribed in the opposite direction. The ORFs were found to share significant homologies and to correspond closely in molecular mass to previously characterized arc genes; thus, they were designated arcA (AD), arcB (ornithine carbamyltransferase), arcC (carbamate kinase), arcD (arginine-ornithine antiporter), arcT (dipeptidase), and arcR (regulator). A putative σ70 promoter (ParcA [TTGTGT-N19-TAGAAT]) was mapped 5′ to arcA by primer extension, and the expression of ParcA was shown to be inducible by arginine and repressible by glucose, in agreement with AD specific activities measured in the wild-type strain. To investigate the function of ArcR in the differential expression of the arc operon, arcR was insertionally inactivated by a KM resistance marker flanked by T4 transcription/translation termination signals, and the expression of ParcA was monitored by primer extension in the wild-type and ArcR-deficient strains. Lower levels of arcA expression, as well as lower levels of AD activity, were consistently observed in the ArcR-deficient strain compared to wild-type cells, regardless of the growth conditions. Thus, ArcR is a transcriptional activator that is required for induction and optimal expression of the S. gordonii ADS gene cluster.

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Barbosa, Flávia Rabelo, Massaru Yokoyama, Pedro Antônio Arraes Pereira et Francisco José Pfeilsticker Zimmermann. « Effect of arcelin protein on the biology of Zabrotes subfasciatus (Boheman 1833), in dry beans ». Pesquisa Agropecuária Brasileira 34, n^o 10 (octobre 1999) : 1805–10. http://dx.doi.org/10.1590/s0100-204x1999001000006.

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Arcelin is a seed protein found in wild beans (Phaseolus vulgaris) which gives resistance to Mexican bean weevil, Zabrotes subfasciatus (Boheman 1833) (Coleoptera: Bruchidae). Studies were carried out with the objective of estimating the effect of four alleles of protein arcelin (Arc1, Arc2, Arc3 and Arc4) on the biology of Z. subfasciatus. The experiment was carried out in laboratory at Embrapa-Centro Nacional de Pesquisa de Arroz e Feijão, in Santo Antônio de Goiás, GO, Brazil, under non controlled conditions. The highest levels of antibiosis to Z. subfasciatus were observed in Arc1, with reduction in the number of eggs, number of emerged adults, adults longevity. In the line Arc2 only reduction in the number of emerged adults was observed. The lines Arc3 and Arc4 showed low efficiency on the reduction of progeny of Z. subfasciatus and effects in the longevity and egg-adult cycle were not detected. Insect sexual ratio was not altered by the presence of Arc1, Arc2, Arc3 and Arc4 in the seeds.

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Barbosa, Flávia R., Massaru Yokoyama, Pedro A. A. Pereira et F. J. P. Zimmermann. « Danos de Zabrotes subfasciatus (Boh.) (Coleoptera : Bruchidae) em linhagens de feijoeiro (Phaseolus vulgaris L.) contendo arcelina ». Anais da Sociedade Entomológica do Brasil 29, n^o 1 (mars 2000) : 113–21. http://dx.doi.org/10.1590/s0301-80592000000100014.

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A arcelina é uma proteína encontrada em feijões silvestres e confere resistência ao caruncho do feijão, Zabrotes subfasciatus (Boh. 1833) (Coleoptera: Bruchidae). Comparando-se às cultivares suscetíveis Porrillo 70 e Goiano Precoce, avaliou-se a contribuição de quatro alelos da arcelina (Arc1, Arc2, Arc3 e Arc4), presentes em quatro linhagens quase isogênicas de feijoeiro, no controle de Z. subfasciatus, no período de 15 a 150 dias de armazenagem, em intervalos de 15 dias. O experimento foi conduzido em condições não controladas, utilizando-se delineamento experimental inteiramente ao acaso, em fatorial 6 x 10. Como resultado da baixa emergência de adultos em Arc1 e Arc2, constataram-se, ao final do período de armazenamento, diferenças significativas na percentagem de sementes danificadas pelo caruncho, entre as linhagens contendo Arc1 (0,0%), Arc2 (8,0%), as testemunhas suscetíveis 'Porrillo 70' (73,7%) e Goiano Precoce (99,3%) e as linhagens Arc3 (86,3%) e Arc4 (48,0%). A percentagem de emergência de plantas, imediatamente antes da armazenagem, variou de 95,3 a 97,3% entre os tratamentos, sem diferenças significativas; após 150 dias de armazenagem a emergência foi de 92% em Arc1, 84,3% em Arc2 e 83% em Arc4, as quais diferiram significativamente de Arc3 (30%), 'Porrillo 70' (41,3%) e 'Goiano Precoce' (6,7%).

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Hong, Kyongsu. « Characterization of the arginine deiminase ofStreptococcus equisubsp.zooepidemicus ». Canadian Journal of Microbiology 52, n^o 9 (1 septembre 2006) : 868–76. http://dx.doi.org/10.1139/w06-041.

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Streptococcus equi subsp. zooepidemicus is an important cause of infectious diseases in horses and rarely humans. Little is known about the virulence factors or protective antigens of S. equi subsp. zooepidemicus. In the present study, I designed original primers based on an alignment of the gene sagp(arcA) from Streptococcus pyogenes encoding streptococcal acid glycoprotein – arginine deiminase (SAGP/AD) to amplify the S. equi subsp. zooepidemicus counterpart sequence by polymerase chain reaction, and I analyzed the sagp(arcA) gene of the organism. Using chromosomal walking steps, I identified a contiguous eight-gene locus involved in SAGP/AD production. Their open reading frames were found to share significant homologies and to correspond closely in molecular mass to previously sequenced arc genes of S. pyogenes, thus they were designated ahrC.2 (arginine repressor), arcR (CRP/FNR transcription regulator), sagp(arcA) (streptococcal acid glycoprotein – arginine deiminase), putative acetyltransferase gene, arcB (ornithine carbamyl transferase), arcD (arginine–ornithine antiporter), arcT (Xaa-His peptidase), and arcC (carbamate kinase). The SAGP homologue of S. equi subsp. zooepidemicus (SzSAGP), encoded by arcA gene of the bacteria (arcA(SZ)), was successfully expressed in Escherichia coli and purified to homogeneity. When in vitro growth inhibitory activity of the recombinant SzSAGP was tested against MOLT-3 cells, it inhibited the growth of the cells during the 3 days of culture in a dose-dependent manner, accompanied by the induction of apoptotic cell death. The recombinant protein also possessed AD activity. By immunoblot analysis using both anti-SzSAGP-SfbI(H8) and anti-SfbI(H8) sera, I was able to demonstrate that the SzSAGP protein is expressed on the streptococcal surface.Key words: SAGP, arginine deiminase, Streptococcus equi subsp. zooepidemicus.

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Gruening, Petra, Marcus Fulde, Peter Valentin-Weigand et Ralph Goethe. « Structure, Regulation, and Putative Function of the Arginine Deiminase System of Streptococcus suis ». Journal of Bacteriology 188, n^o 2 (15 janvier 2006) : 361–69. http://dx.doi.org/10.1128/jb.188.2.361-369.2006.

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ABSTRACT Streptococcus suis is an important cause of infectious diseases in young pigs. Little is known about the virulence factors or protective antigens of S. suis. Recently, we have identified two proteins of the arginine deiminase system (ADS) of S. suis, which were temperature induced and expressed on the streptococcal surface (N. Winterhoff, R. Goethe, P. Gruening, M. Rohde, H. Kalisz, H. E. Smith, and P. Valentin-Weigand, J. Bacteriol. 184:6768-6776, 2002). In the present study, we analyzed the complete ADS of S. suis. Due to their homologies to the recently published S. gordonii ADS genes, the genes for arginine deiminase, ornithine carbamoyl-transferase, and carbamate kinase, which were previously designated adiS, octS, and ckS, respectively, were renamed arcA, arcB, and arcC, respectively. Our data revealed that arcA, arcB, and arcC of the S. suis ADS are transcribed from an operon (arcABC operon). Additionally, putative ADS-associated genes were cloned and sequenced which, however, did not belong to the arcABC operon. These were the flpS gene upstream of the arcABC operon with homology to the flp transcription regulator of S. gordonii and the arcD, arcT, arcH, and argR genes downstream of the arcABC operon with high homologies to a putative arginine-ornithine antiporter, a putative dipeptidase of S. gordonii, a putative β-N-acetylhexosaminidase of S. pneumoniae, and a putative arginine repressor of S. gordonii, respectively. The transcriptional start point of the arcABC operon was determined, and promoter analysis provided evidence that multiple factors contribute to the regulation of the ADS. Thus, a putative binding site for a transcription regulator of the Crp/Fnr family, an ArgR-binding site, and two cis-acting catabolite response elements were identified in the promoter-operator region of the operon. Consistent with this, we could demonstrate that the ADS of S. suis is inducible by arginine and reduced O2 tension and subject to carbon catabolite repression. Furthermore, comparing an arcA knockout mutant in which expression of the three operon-encoded proteins was abolished with the parental wild-type strain showed that the arcABC operon of S. suis contributes to survival under acidic conditions.

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Andryushin, A. « Ice loads on pod unit bodies of ice-going ships ». Transactions of the Krylov State Research Centre S-I, n^o 2 (28 décembre 2020) : 19–30. http://dx.doi.org/10.24937/2542-2324-2020-2-s-i-19-30.

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This paper presents the methodology for determination of ice loads on the elements of pod propulsion units for Arc4-Arc9 ships. The conclusion gives calculation results for ice loads on pod units for Arc5 and Arc7 ships, and compares these results with those obtained as per DNV-GL rules for ice classes PC6, PC5, PC3

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Brual, Typhaine, Géraldine Effantin, Julie Baltenneck, Laetitia Attaiech, Cloé Grosbois, Monique Royer, Jérémy Cigna, Denis Faure, Nicole Hugouvieux-Cotte-Pattat et Erwan Gueguen. « A natural single nucleotide mutation in the small regulatory RNA ArcZ of Dickeya solani switches off the antimicrobial activities against yeast and bacteria ». PLOS Genetics 19, n^o 4 (27 avril 2023) : e1010725. http://dx.doi.org/10.1371/journal.pgen.1010725.

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The necrotrophic plant pathogenic bacterium Dickeya solani emerged in the potato agrosystem in Europe. All isolated strains of D. solani contain several large polyketide synthase/non-ribosomal peptide synthetase (PKS/NRPS) gene clusters. Analogy with genes described in other bacteria suggests that the clusters ooc and zms are involved in the production of secondary metabolites of the oocydin and zeamine families, respectively. A third cluster named sol was recently shown to produce an antifungal molecule. In this study, we constructed mutants impaired in each of the three secondary metabolite clusters sol, ooc, and zms to compare first the phenotype of the D. solani wild-type strain D s0432-1 with its associated mutants. We demonstrated the antimicrobial functions of these three PKS/NRPS clusters against bacteria, yeasts or fungi. The cluster sol, conserved in several other Dickeya species, produces a secondary metabolite inhibiting yeasts. Phenotyping and comparative genomics of different D. solani wild-type isolates revealed that the small regulatory RNA ArcZ plays a major role in the control of the clusters sol and zms. A single-point mutation, conserved in some Dickeya wild-type strains, including the D. solani type strain IPO 2222, impairs the ArcZ function by affecting its processing into an active form.

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Mandin, Pierre, et Susan Gottesman. « Integrating anaerobic/aerobic sensing and the general stress response through the ArcZ small RNA ». EMBO Journal 29, n^o 18 (3 août 2010) : 3094–107. http://dx.doi.org/10.1038/emboj.2010.179.

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Lassak, Jürgen, Anna-Lena Henche, Lucas Binnenkade et Kai M. Thormann. « ArcS, the Cognate Sensor Kinase in an Atypical Arc System of Shewanella oneidensis MR-1 ». Applied and Environmental Microbiology 76, n^o 10 (26 mars 2010) : 3263–74. http://dx.doi.org/10.1128/aem.00512-10.

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ABSTRACT The availability of oxygen is a major environmental factor for many microbes, in particular for bacteria such as Shewanella species, which thrive in redox-stratified environments. One of the best-studied systems involved in mediating the response to changes in environmental oxygen levels is the Arc two-component system of Escherichia coli, consisting of the sensor kinase ArcB and the cognate response regulator ArcA. An ArcA ortholog was previously identified in Shewanella, and as in Escherichia coli, Shewanella ArcA is involved in regulating the response to shifts in oxygen levels. Here, we identified the hybrid sensor kinase SO_0577, now designated ArcS, as the previously elusive cognate sensor kinase of the Arc system in Shewanella oneidensis MR-1. Phenotypic mutant characterization, transcriptomic analysis, protein-protein interaction, and phosphotransfer studies revealed that the Shewanella Arc system consists of the sensor kinase ArcS, the single phosphotransfer domain protein HptA, and the response regulator ArcA. Phylogenetic analyses suggest that HptA might be a relict of ArcB. Conversely, ArcS is substantially different with respect to overall sequence homologies and domain organizations. Thus, we speculate that ArcS might have adopted the role of ArcB after a loss of the original sensor kinase, perhaps as a consequence of regulatory adaptation to a redox-stratified environment.

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Papenfort, Kai, Nelly Said, Tim Welsink, Sacha Lucchini, Jay C. D. Hinton et Jörg Vogel. « Specific and pleiotropic patterns of mRNA regulation by ArcZ, a conserved, Hfq-dependent small RNA ». Molecular Microbiology 74, n^o 1 (octobre 2009) : 139–58. http://dx.doi.org/10.1111/j.1365-2958.2009.06857.x.

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Haddadi, Azita, Alyssa Chaffey, Siew Hon Ng, Damayanthi Yalamati et Heather L. Wilson. « Combination of Innate Immune Modulators as Vaccine Adjuvants in Mice ». Vaccines 8, n^o 4 (1 octobre 2020) : 569. http://dx.doi.org/10.3390/vaccines8040569.

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The development of new, effective, and safe vaccines necessarily requires the identification of new adjuvant(s) to enhance the potency and longevity of antigen-specific immune responses. In the present study, we compare the antibody-mediated and cell-mediated immune (CMI) responses within groups of mice vaccinated subcutaneously with ovalbumin (OVA; as an experimental antigen) plus polyphosphazene (an innate immune modulator), Polyinosinic:polycytidylic acid (poly-I:C; (an RNA mimetic) and glycopeptide ARC5 (which is a Toll-like receptor (TLR), TLR2 ligand and PAM3CSK4 analogue) formulated together in a soluble vaccine. We also investigated the effect of a polymeric nanoparticle of ARC4 and ARC7 (which are a novel muramyl dipeptide analogue and a monophosophoryl lipid A (MPLA) analogue, respectively) plus OVA +/− ARC5 as a subcutaneous vaccine in mice. OVA+ARC4/ARC7 nanoparticle +/− ARC5 triggered a robust and balanced Th1/Th2-type humoral response with significant anti-OVA IgA in serum, and significant interferon (IFN)-γ and interleukin (IL)-17 production in splenocytes after 35 days relative to the controls. Formulation of OVA with ARC4/ARC7 nanoparticles should be investigated for inducing protective immunity against infectious pathogens in mice and other species.

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Gaida, S. M., M. A. Al-Hinai, D. C. Indurthi, S. A. Nicolaou et E. T. Papoutsakis. « Synthetic tolerance : three noncoding small RNAs, DsrA, ArcZ and RprA, acting supra-additively against acid stress ». Nucleic Acids Research 41, n^o 18 (27 juillet 2013) : 8726–37. http://dx.doi.org/10.1093/nar/gkt651.

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Griswold, Ann, Yi-Ywan M. Chen, Jennifer A. Snyder et Robert A. Burne. « Characterization of the Arginine Deiminase Operon of Streptococcus rattus FA-1 ». Applied and Environmental Microbiology 70, n^o 3 (mars 2004) : 1321–27. http://dx.doi.org/10.1128/aem.70.3.1321-1327.2004.

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ABSTRACT The arginine deiminase system (ADS) is of critical importance in oral biofilm pH homeostasis and microbial ecology. The ADS consists of three enzymes. Arginine is hydrolyzed by AD (ArcA) to generate citrulline and ammonia. Citrulline is then converted to ornithine and carbamoylphosphate via ornithine carbamoyltransferase (ArcB). Finally, carbamate kinase (ArcC) transfers a phosphate from carbamoylphosphate to ADP, yielding ATP. Ammonia production from this pathway protects bacteria from lethal acidification, and ATP production provides a source of energy for the cells. The purpose of this study was to initiate a characterization of the arc operon of Streptococcus rattus, the least cariogenic and sole ADS-positive member of the mutans streptococci. Using an arcB gene fragment obtained by degenerate PCRs, the FA-1 arc operon was identified in subgenomic DNA libraries and sequence analysis was performed. Results showed that the genes encoding the AD pathway in S. rattus FA-1 are organized as an arcABCDT-adiR operon gene cluster, including the enzymes of the pathway, an arginine-ornithine antiporter (ArcD) and a putative regulatory protein (AdiR). The arcA transcriptional start site was identified by primer extension, and a σ70-like promoter was mapped 5′ to arcA. Reverse transcriptase PCR was used to establish that arcABCDT could be cotranscribed. Reporter gene fusions and AD assays demonstrated that the operon is regulated by substrate induction and catabolite repression, the latter apparently through a CcpA-dependent pathway.

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Maghnouj, Abdelouahid, Tiago Franco de Sousa Cabral, Victor Stalon et Corinne Vander Wauven. « The arcABDC Gene Cluster, Encoding the Arginine Deiminase Pathway of Bacillus licheniformis, and Its Activation by the Arginine Repressor ArgR ». Journal of Bacteriology 180, n^o 24 (15 décembre 1998) : 6468–75. http://dx.doi.org/10.1128/jb.180.24.6468-6475.1998.

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ABSTRACT The arginine deiminase pathway enables Bacillus licheniformis to grow anaerobically on arginine. Both the presence of arginine and anaerobiosis are needed to trigger induction of the pathway. In this study we have cloned and sequenced thearc genes encoding the pathway. They appear clustered in an operon-like structure in the order arcA (arginine deiminase), arcB (ornithine carbamoyltransferase),arcD (putative arginine-ornithine antiporter),arcC (carbamate kinase). It was found that B. licheniformis has an arginine repressor, ArgR, homologous to theB. subtilis arginine repressor AhrC. Mutants affected inargR were isolated. These mutants have lost both repression by arginine of the anabolic ornithine carbamoyltransferase and induction of the arginine deiminase pathway. Electrophoretic band shift experiments and DNase I footprinting revealed that in the presence of arginine, ArgR binds to a site upstream from the arcpromoter. The binding site is centered 108 nucleotides upstream from the transcription start point and contains a single Arg box.

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Rechnitzer, Hagai, Shlomo Rottem et Richard Herrmann. « Reconstitution of an Active Arginine Deiminase Pathway in Mycoplasma pneumoniae M129 ». Infection and Immunity 81, n^o 10 (29 juillet 2013) : 3742–49. http://dx.doi.org/10.1128/iai.00441-13.

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ABSTRACTSome species of the genusMycoplasmacode for the arginine deiminase pathway (ADI), which enables these bacteria to produce ATP from arginine by the successive reaction of three enzymes: arginine deiminase (ArcA), ornithine carbamoyltransferase (ArcB), and carbamate kinase (ArcC). It so far appears that independently isolated strains ofMycoplasma pneumoniaeencode an almost identical truncated version of the ADI pathway in which the proteins ArcA and ArcB have lost their original enzymatic activities due to the deletion of significant regions of these proteins. To study the consequences of a functional ADI pathway,M. pneumoniaeM129 was successfully transformed with the cloned functionalarcA,arcB, andarcCgenes fromMycoplasma fermentans. Enzymatic tests showed that while theM. pneumoniaeArcAB and ArcABC transformants possess functional arginine deiminase, ornithine carbamoyltransferase, and carbamate kinase, they were unable to grow on arginine as the sole energy source. Nevertheless, infection of a lung epithelial cell line, A549, with theM. pneumoniaetransformants showed that almost 100% of the infected host cells were nonviable, while most of the lung cells infected with nontransformedM. pneumoniaewere viable under the same experimental conditions.

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Yuan, Xiaochen, Quan Zeng, Devanshi Khokhani, Fang Tian, Geoffrey B. Severin, Christopher M. Waters, Jingsheng Xu et al. « A feed‐forward signalling circuit controls bacterial virulence through linking cyclic di‐GMP and two mechanistically distinct sRNAs, ArcZ and RsmB ». Environmental Microbiology 21, n^o 8 (13 mai 2019) : 2755–71. http://dx.doi.org/10.1111/1462-2920.14603.

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Mun, So Yeong, et Hae Choon Chang. « Characterization of Weissella koreensis SK Isolated from Kimchi Fermented at Low Temperature (around 0 °C) Based on Complete Genome Sequence and Corresponding Phenotype ». Microorganisms 8, n^o 8 (29 juillet 2020) : 1147. http://dx.doi.org/10.3390/microorganisms8081147.

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This study identified lactic acid bacteria (LAB) that play a major role in kimchi fermented at low temperature, and investigated the safety and functionality of the LAB via biologic and genomic analyses for its potential use as a starter culture or probiotic. Fifty LAB were isolated from 45 kimchi samples fermented at −1.5~0 °C for 2~3 months. Weissella koreensis strains were determined as the dominant LAB in all kimchi samples. One strain, W. koreensis SK, was selected and its phenotypic and genomic features characterized. The complete genome of W. koreensis SK contains one circular chromosome and plasmid. W. koreensis SK grew well under mesophilic and psychrophilic conditions. W. koreensis SK was found to ferment several carbohydrates and utilize an alternative carbon source, the amino acid arginine, to obtain energy. Supplementation with arginine improved cell growth and resulted in high production of ornithine. The arginine deiminase pathway of W. koreensis SK was encoded in a cluster of four genes (arcA-arcB-arcD-arcC). No virulence traits were identified in the genomic and phenotypic analyses. The results indicate that W. koreensis SK may be a promising starter culture for fermented vegetables or fruits at low temperature as well as a probiotic candidate.

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He, Shoukui, Zeqiang Zhan, Chunlei Shi, Siyun Wang et Xianming Shi. « Ethanol at Subinhibitory Concentrations Enhances Biofilm Formation in Salmonella Enteritidis ». Foods 11, n^o 15 (27 juillet 2022) : 2237. http://dx.doi.org/10.3390/foods11152237.

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The survival of Salmonella Enteritidis in the food chain is relevant to its biofilm formation capacity, which is influenced by suboptimal environmental conditions. Here, biofilm formation pattern of this bacterium was assessed in the presence of ethanol at sub-minimal inhibitory concentrations (sub-MICs) by microtiter plate assays, cell characteristic analyses, and gene expression tests. It was observed that ethanol at subinhibitory concentrations (1/4 MIC, 2.5%; 1/2 MIC, 5.0%) was able to stimulate biofilm formation in S. Enteritidis. The OD595 value (optical density at 595 nm) used to quantify biofilm production was increased from 0.14 in control groups to 0.36 and 0.63 under 2.5% and 5.0% ethanol stresses, respectively. Ethanol was also shown to reduce bacterial swimming motility and enhance cell auto-aggregation ability. However, other cell characteristics such as swarming activity, initial attachment and cell surface hydrophobicity were not remarkedly impacted by ethanol. Reverse transcription quantitative real-time PCR (RT-qPCR) analysis further revealed that the luxS gene belonging to a quorum-sensing system was upregulated by 2.49- and 10.08-fold in the presence of 2.5% and 5.0% ethanol, respectively. The relative expression level of other biofilm-related genes (adrA, csgB, csgD, and sdiA) and sRNAs (ArcZ, CsrB, OxyS, and SroC) did not obviously change. Taken together, these findings suggest that decrease in swimming motility and increase in cell auto-aggregation and quorum sensing may result in the enhancement of biofilm formation by S. Enteritidis under sublethal ethanol stress.

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Yuan, Xiaochen, Manda Yu et Ching-Hong Yang. « Innovation and Application of the Type III Secretion System Inhibitors in Plant Pathogenic Bacteria ». Microorganisms 8, n^o 12 (9 décembre 2020) : 1956. http://dx.doi.org/10.3390/microorganisms8121956.

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Many Gram-negative pathogenic bacteria rely on a functional type III secretion system (T3SS), which injects multiple effector proteins into eukaryotic host cells, for their pathogenicity. Genetic studies conducted in different host-microbe pathosystems often revealed a sophisticated regulatory mechanism of their T3SSs, suggesting that the expression of T3SS is tightly controlled and constantly monitored by bacteria in response to the ever-changing host environment. Therefore, it is critical to understand the regulation of T3SS in pathogenic bacteria for successful disease management. This review focuses on a model plant pathogen, Dickeyadadantii, and summarizes the current knowledge of its T3SS regulation. We highlight the roles of several T3SS regulators that were recently discovered, including the transcriptional regulators: FlhDC, RpoS, and SlyA; the post-transcriptional regulators: PNPase, Hfq with its dependent sRNA ArcZ, and the RsmA/B system; and the bacterial second messenger cyclic-di-GMP (c-di-GMP). Homologs of these regulatory components have also been characterized in almost all major bacterial plant pathogens like Erwiniaamylovora, Pseudomonassyringae, Pectobacterium spp., Xanthomonas spp., and Ralstonia spp. The second half of this review shifts focus to an in-depth discussion of the innovation and development of T3SS inhibitors, small molecules that inhibit T3SSs, in the field of plant pathology. This includes T3SS inhibitors that are derived from plant phenolic compounds, plant coumarins, and salicylidene acylhydrazides. We also discuss their modes of action in bacteria and application for controlling plant diseases.

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Weawsiangsang, Sattaporn, Nontaporn Rattanachak, Touchkanin Jongjitvimol, Theerasak Jaifoo, Pensri Charoensit, Jarupa Viyoch, Sukunya Ross, Gareth M. Ross, Robert A. Baldock et Jirapas Jongjitwimol. « Hydroquinine Inhibits the Growth of Multidrug-Resistant Pseudomonas aeruginosa via the Suppression of the Arginine Deiminase Pathway Genes ». International Journal of Molecular Sciences 24, n^o 18 (10 septembre 2023) : 13914. http://dx.doi.org/10.3390/ijms241813914.

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Hydroquinine has antimicrobial potential with demonstrated activity against several bacteria, including multidrug-resistant (MDR) P. aeruginosa reference strains. Despite this, there is limited evidence confirming the antibacterial activity of hydroquinine against clinical isolates and the underlying mechanism of action. Here, we aimed to investigate the antibacterial effect of hydroquinine in clinical P. aeruginosa strains using phenotypic antimicrobial susceptibility testing and synergistic testing. In addition, we examined the potential inhibitory mechanisms against MDR P. aeruginosa isolates using informatic-driven molecular docking analysis in combination with RT-qPCR. We uncovered that hydroquinine inhibits and kills clinical P. aeruginosa at 2.50 mg/mL (MIC) and 5.00 mg/mL (MBC), respectively. Hydroquinine also showed partial synergistic effects with ceftazidime against clinical MDR P. aeruginosa strains. Using SwissDock, we identified potential interactions between arginine deiminase (ADI)-pathway-related proteins and hydroquinine. Furthermore, using RT-qPCR, we found that hydroquinine directly affects the mRNA expression of arc operon. We demonstrated that the ADI-related genes, including the arginine/ornithine antiporter (arcD) and the three enzymes (arginine deiminase (arcA), ornithine transcarbamylase (arcB), and carbamate kinase (arcC)), were significantly downregulated at a half MIC of hydroquinine. This study is the first report that the ADI-related proteins are potential molecular targets for the inhibitory effect of hydroquinine against clinically isolated MDR P. aeruginosa strains.

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Peña-Sandoval, Gabriela R., Ohsuk Kwon et Dimitris Georgellis. « Requirement of the Receiver and Phosphotransfer Domains of ArcB for Efficient Dephosphorylation of Phosphorylated ArcA In Vivo ». Journal of Bacteriology 187, n^o 9 (1 mai 2005) : 3267–72. http://dx.doi.org/10.1128/jb.187.9.3267-3272.2005.

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ABSTRACT The Arc two-component system, comprising the ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous genes in response to the respiratory conditions of growth. Under anoxic growth conditions, ArcB autophosphorylates and transphosphorylates ArcA, which in turn represses or activates its target operons. Under aerobic growth conditions, phosphorylated ArcA (ArcA-P) dephosphorylates and its transcriptional regulation is released. The dephosphorylation of ArcA-P has been shown to occur, at least in vitro, via an ArcAAsp54-P → ArcBHis717-P → ArcBAsp576-P → Pi reverse phosphorelay. In this study, the physiological significance of this pathway was assessed. The results demonstrate that the receiver and phosphotransfer domains of the tripartite sensor kinase ArcB are necessary and sufficient for efficient ArcA-P dephosphorylation in vivo.

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Matsushika, Akinori, et Takeshi Mizuno. « A Dual-Signaling Mechanism Mediated by the ArcB Hybrid Sensor Kinase Containing the Histidine-Containing Phosphotransfer Domain in Escherichia coli ». Journal of Bacteriology 180, n^o 15 (1 août 1998) : 3973–77. http://dx.doi.org/10.1128/jb.180.15.3973-3977.1998.

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ABSTRACT The two components ArcB and ArcA play a crucial role in the signal transduction implicated in the complex transcriptional regulatory network that allows Escherichia coli to sense various respiratory growth conditions. ArcB is a hybrid sensor kinase having multiple phosphorylation sites in its primary amino acid sequence, including a transmitter, a receiver, and a histidine-containing phosphotransfer (HPt) domain. ArcA is a DNA-binding transcriptional regulator with a receiver domain. Results of recent in vitro studies revealed multistep His-to-Asp phosphotransfer circuitry in the ArcB-ArcA signaling system. For this report we conducted a series of in vivo experiments using a set of crucial ArcB mutants to evaluate the regulation of the sdh operon. The results suggested that the phosphorylated His-717 site in the HPt domain of ArcB is essential for anaerobic repression of sdh. Nonetheless, the ArcB mutant lacking this crucial His-717 site does not necessarily exhibit a null phenotype with respect to ArcB-ArcA signaling. The HPt mutant appears to maintain an ability to signal ArcA, particularly under aerobic conditions, which results in a significant repression ofsdh. Based on these and other in vivo results, we propose a model in which ArcB functions in its own right as a dual-signaling sensor that is capable of propagating two types of stimuli through two distinct phosphotransfer pathways.

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Rodriguez, Claudia, Ohsuk Kwon et Dimitris Georgellis. « Effect of d-Lactate on the Physiological Activity of the ArcB Sensor Kinase in Escherichia coli ». Journal of Bacteriology 186, n^o 7 (1 avril 2004) : 2085–90. http://dx.doi.org/10.1128/jb.186.7.2085-2090.2004.

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ABSTRACT The Arc two-component system, comprising the ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous genes in response to the respiratory growth conditions. Under anoxic growth conditions ArcB autophosphorylates and transphosphorylates ArcA, which in turn represses or activates its target operons. The anaerobic metabolite d-lactate has been shown to stimulate the in vitro autophosphorylating activity of ArcB. In this study, the in vivo effect of d-lactate on the kinase activity of ArcB was assessed. The results demonstrate that d-lactate does not act as a direct signal for activation of ArcB, as previously proposed, but acts as a physiologically significant effector that amplifies ArcB kinase activity.

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Barcelona-Andrés, Belén, Alberto Marina et Vicente Rubio. « Gene Structure, Organization, Expression, and Potential Regulatory Mechanisms of Arginine Catabolism in Enterococcus faecalis ». Journal of Bacteriology 184, n^o 22 (15 novembre 2002) : 6289–300. http://dx.doi.org/10.1128/jb.184.22.6289-6300.2002.

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ABSTRACT Although Enteroccus faecalis is the paradigm for biochemical studies on the arginine deiminase (ADI) pathway of fermentative arginine catabolism, little genetic information exists on this pathway in this organism. We fill this important gap by characterizing, in an 8,228-bp region cloned from a λgt11 genomic library of E. faecalis, a five-gene cluster forming a transcriptional unit (revealed by Northern blots and primer extension in E. faecalis) that corresponds to the ADI operon. Four additional genes in the opposite DNA strand and one in the same DNA strand are also identified. Studies on the protein products, including heterologous expression and/or sequence comparisons, allow us to ascertain or propose functions for all but 1 of the 10 genes. The ADI operon genes, arcABCRD, encode, respectively, ADI, ornithine transcarbamylase, carbamate kinase, a putative Crp/Fnr-type regulator (ArcR), and a putative ornithine-arginine antiporter (ArcD). Arginine induces the expression of arcABCRD, most likely by means of two homologous ArgR/AhrC-type regulators encoded by two genes, argR1 and argR2, that precede arcABCRD in each DNA strand and that are transcribed monocistronically, their transcription being influenced differentially by glucose and arginine. Potential ArgR1/ArgR2 (double and single) binding sequences are found in the promoter regions of arcA and of argR1/argR2 themselves. In addition, putative binding sequences for ArcR and for CcpA are found, respectively, in the argR1/argR2 and arcA promoter regions. Of the three other genes identified, two form a transcriptional unit and encode a putative metal-sensitive transcriptional regulator (ArsR) and a cysteine protease.

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Spano, G., G. Chieppa, L. Beneduce et S. Massa. « Expression analysis of putative arcA, arcB and arcC genes partially cloned from Lactobacillus plantarum isolated from wine ». Journal of Applied Microbiology 96, n^o 1 (janvier 2004) : 185–93. http://dx.doi.org/10.1046/j.1365-2672.2003.02132.x.

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Kwon, Ohsuk, Dimitris Georgellis et E. C. C. Lin. « Phosphorelay as the Sole Physiological Route of Signal Transmission by the Arc Two-Component System ofEscherichia coli ». Journal of Bacteriology 182, n^o 13 (1 juillet 2000) : 3858–62. http://dx.doi.org/10.1128/jb.182.13.3858-3862.2000.

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ABSTRACT The Arc two-component system, comprising a tripartite sensor kinase (ArcB) and a response regulator (ArcA), modulates the expression of numerous genes involved in respiratory functions. In this study, the steps of phosphoryl group transfer from phosphorylated ArcB to ArcA were examined in vivo by using single copies of wild-type and mutantarcB alleles. The results indicate that the signal transmission occurs solely by His-Asp-His-Asp phosphorelay.

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Padilla-Vaca, Felipe, Javier de la Mora, Rodolfo García-Contreras, Jorge Humberto Ramírez-Prado, Marcos Vicente-Gómez, Francisco Vargas-Gasca, Fernando Anaya-Velázquez et al. « Theoretical study of ArcB and its dimerization, interaction with anaerobic metabolites, and activation of ArcA ». PeerJ 11 (13 octobre 2023) : e16309. http://dx.doi.org/10.7717/peerj.16309.

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The complex metabolism of Escherichia coli has been extensively studied, including its response to oxygen availability. The ArcA/B two-component system (TCS) is the key regulator for the transition between these two environmental conditions and has been thoroughly characterized using genetic and biochemical approaches. Still, to date, limited structural data is available. The breakthrough provided by AlphaFold2 in 2021 has brought a reliable tool to the scientific community for assessing the structural features of complex proteins. In this report, we analyzed the structural aspects of the ArcA/B TCS using AlphaFold2 models. The models are consistent with the experimentally determined structures of ArcB kinase. The predicted structure of the dimeric form of ArcB is consistent with the extensive genetic and biochemical data available regarding mechanistic signal perception and regulation. The predicted interaction of the dimeric form of ArcB with its cognate response regulator (ArcA) is also consistent with both the forward and reverse phosphotransfer mechanisms. The ArcB model was used to detect putative binding cavities to anaerobic metabolites, encouraging testing of these predictions experimentally. Finally, the highly accurate models of other ArcB homologs suggest that different experimental approaches are needed to determine signal perception in kinases lacking the PAS domain. Overall, ArcB is a kinase with features that need further testing, especially in determining its crystal structure under different conditions.

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Li, Fangzhen, Huaping Zhong, Kehui Ouyang, Xiaomin Zhao et Yuzhe Li. « Estimation and Mapping of Actual and Potential Grassland Root Carbon Storage : A Case Study in the Altay Region, China ». Agronomy 12, n^o 11 (26 octobre 2022) : 2632. http://dx.doi.org/10.3390/agronomy12112632.

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The actual root carbon storage (ARCS) and potential root carbon storage (PRCS) of grasslands play an important role in the global carbon balance and carbon neutralization. However, estimation of these indicators is difficult. In addition, their spatial patterns and crucial driving factors also require clarification. In this study, an approach for accurate estimation of ARCS and PRCS was developed incorporating a support vector machine model and high-accuracy surface modeling. Based on field data collected from Altay Prefecture in 2015, the estimation accuracy (R2) of root biomass in the 0–10, 10–20, and 20–30 cm soil layers of grassland were 0.73, 0.63, and 0.60, respectively. In addition, the spatial patterns of actual root carbon density (ARCD) and potential root carbon density (PRCD) were analyzed. The ARCD increased with the increase in elevation. High PRCD was located on hillsides with a gentle slope. The dominant interaction factors for the ARCD spatial pattern were temperature and precipitation, whereas the main interaction factors for the PRCD pattern were temperature and slope. The grassland ARCS and PRCS in Altay Prefecture were estimated to be 48.52 and 22.69 Tg C, respectively. We suggest there is considerable capacity to increase grassland ARCS in the study area.

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Georgellis, Dimitris, Ohsuk Kwon, Edmund C. C. Lin, Sandy M. Wong et Brian J. Akerley. « Redox Signal Transduction by the ArcB Sensor Kinase of Haemophilus influenzae Lacking the PAS Domain ». Journal of Bacteriology 183, n^o 24 (15 décembre 2001) : 7206–12. http://dx.doi.org/10.1128/jb.183.24.7206-7212.2001.

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ABSTRACT The Arc (anoxic redox control) two-component signal transduction system of Escherichia coli, which comprises the tripartite ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous operons in response to redox conditions of growth. We demonstrate that the arcA and arcBgenes of Haemophilus influenzae specify a two-component system. The Arc proteins of the two bacterial species sufficiently resemble each other that they can participate in heterologous transphosphorylation in vitro. Moreover, the Arc system of H. influenzae mediates transcriptional control according to the redox condition of growth both autologously in its own host and homologously in E. coli, indicating a high degree of functional conservation of the signal transduction system. The H. influenzae ArcB, however, lacks the PAS domain present in the region of E. coli ArcB linking the transmembrane to the cytosolic catalytic domains. Because the PAS domain participates in signal reception in a variety of sensory proteins, including sensors of molecular oxygen and redox state, a similar role was previously ascribed to it in ArcB. Our results demonstrate that the ArcB protein of H. influenzae mediates signal transduction in response to redox conditions of growth despite the absence of the PAS domain.

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Batista, Rafael Oliveira, Antonio Teixeira de Matos, Fernando França da Cunha et Paola Alfonsa Lo Monaco. « OBSTRUÇÃO DE GOTEJADORES UTILIZADOS PARA A APLICAÇÃO DE ÁGUA RESIDUÁRIA DA DESPOLPA DOS FRUTOS DO CAFEEIRO ». IRRIGA 10, n^o 3 (5 août 2005) : 299–305. http://dx.doi.org/10.15809/irriga.2005v10n3p299-305.

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OBSTRUÇÃO DE GOTEJADORES UTILIZADOS PARA A APLICAÇÃO DE ÁGUA RESIDUÁRIA DA DESPOLPA DOS FRUTOS DO CAFEEIRO Rafael Oliveira Batista; Antonio Teixeira de Matos; Fernando França da Cunha; Paola Alfonsa Lo MonacoDepartamento de Engenharia Agrícola, Universidade Federal de Viçosa , Viçosa, MG. 1 RESUMO A realização deste trabalho objetivou identificar os principais fatores causadores de entupimento em gotejadores tipo fita, quando utilizados para a aplicação de água residuária bruta da despolpa dos frutos do cafeeiro (ARCB) e tratada em filtro orgânico (ARCF). Foi montada uma estrutura hidráulica de avaliação, constituída de gotejadores do modelo AQUA-TRAXX, não autocompensante, posicionados no espaçamento de0,3 m. Manteve-se a pressão de serviço no início das linhas laterais em 101 kPa, e quantificaram-se a intervalos de 36 horas, as vazões dos gotejadores, até a obtenção de um tempo total de 144 horas de operação do sistema. Com a aplicação de ARCB, houve redução de 100% no CUD após 36 horas e, com a aplicação da ARCF, essa redução ocorreu após 144 horas de funcionamento do sistema. A utilização do filtro orgânico retardou o entupimento dos gotejadores, entretanto, não preveniu o desenvolvimento do filme biológico na tubulação e junto aos emissores. A formação de biofilme foi resultante da interação entre bactérias formadoras de mucilagens (principalmente aeróbias mesófilas, para a ARCB, e enterobactérias, para a ARCF) e sólidos suspensos e dissolvidos, consistindo no principal fator de entupimento parcial e total dos gotejadores. UNITERMOS: Biofilme, entupimento, emissores. BATISTA, R. O.; MATOS, A. T. DE; CUNHA, F. F. DA; LOMONACO, P. A. OBSTRUCTION OF DRIP TAPE USED FOR APPLYING WASTEWATER FROM COFFEE FRUITS PULPING 2 ABSTRACT This study aimed to identify the main factors of the drip tape clogging, when used in the application of untreated wastewater from coffee fruit pulping (ARCB) and treated wastewater from an organic filter (ARCF). For that, a hydraulic structure of evaluation was built, consisting of non-pressure compensating drippers of the model AQUA-TRAXX positioned in 0.3m spacing. Service pressure was kept, in the beginning of the lateral lines, at 101 kPa; the discharges of the drippers were quantified every 36 hours, until a total time of 144 hours of the system operation. For the ARCB application, the CUD reduction was 100%, after 36 hours of the system operation, and for the ARCF application, this reduction was verified after 144 hours. The use of the organic filter delayed the clogging of the drippers but this did not prevent the biofilm development on the tubes and emitters. The biofilm formation was resultant of the interaction between mucilage producer bacteria (mainly aerobic mesophilic, for the ARCB, and enterobacteria, for the ARCF) and suspended and dissolved solids that consisted the main factor of partial and total clogging of drippers. KEYWORDS: Biofilm, clogging, emitters.

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Feng, Youjun, et John E. Cronan. « Overlapping Repressor Binding Sites Result in Additive Regulation of Escherichia coli FadH by FadR and ArcA ». Journal of Bacteriology 192, n^o 17 (9 juillet 2010) : 4289–99. http://dx.doi.org/10.1128/jb.00516-10.

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ABSTRACT Escherichia coli fadH encodes a 2,4-dienoyl reductase that plays an auxiliary role in β-oxidation of certain unsaturated fatty acids. In the 2 decades since its discovery, FadH biochemistry has been studied extensively. However, the genetic regulation of FadH has been explored only partially. Here we report mapping of the fadH promoter and document its complex regulation by three independent regulators, the fatty acid degradation FadR repressor, the oxygen-responsive ArcA-ArcB two-component system, and the cyclic AMP receptor protein-cyclic AMP (CRP-cAMP) complex. Electrophoretic mobility shift assays demonstrated that FadR binds to the fadH promoter region and that this binding can be specifically reversed by long-chain acyl-coenzyme A (CoA) thioesters. In vivo data combining transcriptional lacZ fusion and real-time quantitative PCR (qPCR) analyses indicated that fadH is strongly repressed by FadR, in agreement with induction of fadH by long-chain fatty acids. Inactivation of arcA increased fadH transcription by >3-fold under anaerobic conditions. Moreover, fadH expression was increased 8- to 10-fold under anaerobic conditions upon deletion of both the fadR and the arcA gene, indicating that anaerobic expression is additively repressed by FadR and ArcA-ArcB. Unlike fadM, a newly reported member of the E. coli fad regulon that encodes another auxiliary β-oxidation enzyme, fadH was activated by the CRP-cAMP complex in a manner similar to those of the prototypical fad genes. In the absence of the CRP-cAMP complex, repression of fadH expression by both FadR and ArcA-ArcB was very weak, suggesting a possible interplay with other DNA binding proteins.

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Perrenoud, Annik, et Uwe Sauer. « Impact of Global Transcriptional Regulation by ArcA, ArcB, Cra, Crp, Cya, Fnr, and Mlc on Glucose Catabolism in Escherichia coli ». Journal of Bacteriology 187, n^o 9 (1 mai 2005) : 3171–79. http://dx.doi.org/10.1128/jb.187.9.3171-3179.2005.

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ABSTRACT Even though transcriptional regulation plays a key role in establishing the metabolic network, the extent to which it actually controls the in vivo distribution of metabolic fluxes through different pathways is essentially unknown. Based on metabolism-wide quantification of intracellular fluxes, we systematically elucidated the relevance of global transcriptional regulation by ArcA, ArcB, Cra, Crp, Cya, Fnr, and Mlc for aerobic glucose catabolism in batch cultures of Escherichia coli. Knockouts of ArcB, Cra, Fnr, and Mlc were phenotypically silent, while deletion of the catabolite repression regulators Crp and Cya resulted in a pronounced slow-growth phenotype but had only a nonspecific effect on the actual flux distribution. Knockout of ArcA-dependent redox regulation, however, increased the aerobic tricarboxylic acid (TCA) cycle activity by over 60%. Like aerobic conditions, anaerobic derepression of TCA cycle enzymes in an ArcA mutant significantly increased the in vivo TCA flux when nitrate was present as an electron acceptor. The in vivo and in vitro data demonstrate that ArcA-dependent transcriptional regulation directly or indirectly controls TCA cycle flux in both aerobic and anaerobic glucose batch cultures of E. coli. This control goes well beyond the previously known ArcA-dependent regulation of the TCA cycle during microaerobiosis.

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Peña-Sandoval, Gabriela R., et Dimitris Georgellis. « The ArcB Sensor Kinase of Escherichia coli Autophosphorylates by an Intramolecular Reaction ». Journal of Bacteriology 192, n^o 6 (22 janvier 2010) : 1735–39. http://dx.doi.org/10.1128/jb.01401-09.

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ABSTRACT The Arc two-component system, comprising the ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous genes in response to the respiratory conditions of growth. ArcB is a tripartite histidine kinase whose activity is regulated by the oxidation of two cytosol-located redox-active cysteine residues that participate in intermolecular disulfide bond formation. Here we show that ArcB autophosphorylates through an intramolecular reaction which diverges from the usually envisaged intermolecular autophosphorylation of homodimeric histidine kinases.

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Tsybulkin, G. A. « Effect of own magnetic fields on electric arcs in tandem-arc welding ». Paton Welding Journal 2018, n^o 3 (28 mars 2018) : 12–15. http://dx.doi.org/10.15407/tpwj2018.03.02.

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Novella, Nicholas S., et Wassila M. Thiaw. « African Rainfall Climatology Version 2 for Famine Early Warning Systems ». Journal of Applied Meteorology and Climatology 52, n^o 3 (mars 2013) : 588–606. http://dx.doi.org/10.1175/jamc-d-11-0238.1.

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AbstractThis paper describes a new gridded, daily 29-yr precipitation estimation dataset centered over Africa at 0.1° spatial resolution. Called the African Rainfall Climatology, version 2 (ARC2), it is a revision of the first version of the ARC. Consistent with the operational Rainfall Estimation, version 2, algorithm (RFE2), ARC2 uses inputs from two sources: 1) 3-hourly geostationary infrared (IR) data centered over Africa from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) and 2) quality-controlled Global Telecommunication System (GTS) gauge observations reporting 24-h rainfall accumulations over Africa. The main difference with ARC1 resides in the recalibration of all Meteosat First Generation (MFG) IR data (1983–2005). Results show that ARC2 is a major improvement over ARC1. It is consistent with other long-term datasets, such as the Global Precipitation Climatology Project (GPCP) and Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP), with correlation coefficients of 0.86 over a 27-yr period. However, a marginal summer dry bias that occurs over West and East Africa is examined. Daily validation with independent gauge data shows RMSEs of 11.3, 13.4, and 14, respectively, for ARC2, Tropical Rainfall Measuring Mission Multisatellite Precipitation Analysis 3B42, version 6 (3B42v6), and the CPC morphing technique (CMORPH) for the West African summer season. The ARC2 RMSE is slightly higher for Ethiopia than those of CMORPH and 3B42v6. Both daily and monthly validations suggested that ARC2 underestimations may be attributed to the unavailability of daily GTS gauge reports in real time, and deficiencies in the satellite estimate associated with precipitation processes over coastal and orographic areas. However, ARC2 is expected to provide users with real-time monitoring of the daily evolution of precipitation, which is instrumental in improved decision making in famine early warning systems.

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Kuroboshi, Manabu, Nobuko Yamada, Yoko Takebe et Tamejiro Hiyama. « Stereoselective synthesis of (E)-ArCFCFR and (E)-ArCHCFR from ArCH(OH)CFBr2 ». Tetrahedron Letters 36, n^o 35 (août 1995) : 6271–74. http://dx.doi.org/10.1016/0040-4039(95)01257-i.

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Uahabi, Kaoutar Lamrini, et Mohammed Zaoui. « Behavior of the Trinomial ArcsB(n,k,r)when0<α<1 ». International Journal of Mathematics and Mathematical Sciences 2007 (2007) : 1–8. http://dx.doi.org/10.1155/2007/91535.

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We deal with the familyB(n,k,r)of trinomial arcs defined as the set of roots of the trinomial equationzn=αzk+(1−α), wherez=ρeiθis a complex number,nandkare two integers such that0<k<n, andαis a real number between0and1. These arcsB(n,k,r)are continuous arcs inside the unit disk, expressed in polar coordinates(ρ,θ). The question is to prove thatρ(θ)is a decreasing function, for each trinomial arcB(n,k,r).

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Shroff, Namita P., Moiz A. Charania et Daad A. Saffarini. « ArcB1, a Homolog of Escherichia coli ArcB, Regulates Dimethyl Sulfoxide Reduction in Shewanella oneidensis MR-1 ». Journal of Bacteriology 192, n^o 12 (16 avril 2010) : 3227–30. http://dx.doi.org/10.1128/jb.01695-09.

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ABSTRACT Shewanella oneidensis is a metal reducer that uses the cyclic AMP receptor protein, CRP, to regulate anaerobic respiration. In addition, ArcA So is required for anaerobic growth with dimethyl sulfoxide (DMSO) and plays a role in aerobic respiration. The sensor kinase that activates ArcA So in S. oneidensis is not known. ArcB1 So , a homolog of the Escherichia coli sensor kinase ArcB Ec , was identified and found to be required for DMSO reductase gene expression. In combination with HptA, ArcB1 So complemented an E. coli arcBEc mutant. ArcA So , ArcB1 So , and HptA appear to constitute a two-component signal transduction system that regulates DMSO reduction in S. oneidensis.

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García Baena, Pablo, et Mark Aldrich. « La fuente del arco / The Fountain in the Arch ». Sirena : poesia, arte y critica 2006, n^o 2 (2006) : 106–7. http://dx.doi.org/10.1353/sir.2006.0129.

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Makovický, Pa, M. Milerski, M. Margetín, Pe Makovický et M. Nagy. « Paramètres génétiques de la taille des citernes de lait chez les brebis diagnostiqués par échographie parmi les races : improved Valachian, Tsigai, Lacaune et leurs croisements ». Archivos de Zootecnia 64, n^o 247 (10 décembre 2015) : 403–8. http://dx.doi.org/10.21071/az.v64i248.427.

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La taille de la citerne de lait a été diagnostiquée chez les brebis en utilisant l’échographie et la sonde linéaire de 3,5 MHz de deux façons: La méthode de côté et celle de bas. L’échographie a été faite à partir de chaque scan et ensuite la taille du réservoir à gauche et à droite a été mesurée en utilisant la technique numérique. Les deux citernes ont été scannées environ 12 heures après la dernière traite. L’espace gauche de la citerne (ALC1; 1.933.35 mm2) et celui de droite (ARC1; 1.970.72 mm2), détectés par la méthode de côté, ont été diagnostiqués à plusieurs reprises chez 378 brebis (pendant l’allaitement ainsi qu’entre lactations); un total de 1198 mesures ont été effectuées. L’espace gauche de la citerne (ALC2; 2.137.67 mm2) et de droite (ARC2; 2.171.12 mm2), détectés par la méthode du bas, ont également été diagnostiqués à plusieurs reprises, notamment chez 265 brebis; 753 mesures ont été réalisées au total. La somme des deux zones de section transversale détectées par la méthode de côté (SLRC1) était de 3904.07 mm2, et celle détectée par la méthode de fond (SLRC2) était 4308.77 mm2. Les données primaires ont été traitées en utilisant la méthodologie REML et le modèle animal trait multiple, en utilisant des programmes comme REMLF90 et VCE 4.0. En plus de l’effet génétique additif aléatoire des animaux et l’effet permanent des brebis, les modèles incluent l’année de contrôle comme facteur fixe (7 ou 5 niveaux), un stade de lactation (4 niveaux), un groupe de race (9 niveaux) et la parité (3 niveaux). Nous avons trouvé des valeurs plus élevées de h2 pour les paramètres diagnostiqués par la méthode du bas. Le coefficient d’héritabilité pour ALC1 et ALC2 était de 0.07 et 0.18, respectivement; pour ARC1 et ARC2 de 0.17 et 0.2, resp.; et pour SLRC1 et SLRC2 de 0.12 et 0.17, respectivement. Les corrélations génétiques entre ARC1 et ARC1 ou ARC2 et ARC2 étaient élevées (rg= 0.73 ou 0.910). De même, les corrélations entre la taille de la citerne gauche et/ou droite, et la taille totale des deux citernes étaient élevées avec les deux modes de scan (rg= 0.90 à 0.98). En conclusion, la mesure de la taille des citernes de lait par la méthode de côté est plus recommandée, bien que les mesures avec la méthode du bas montrent des coefficients d’héritabilité légèrement plus élevés.

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Mcandrew, Rosemary S., Bradley J. S. C. Olson, Deena K. Kadirjan-Kalbach, Cecilia L. Chi-Ham, Stanislav Vitha, John E. Froehlich et Katherine W. Osteryoung. « In vivo quantitative relationship between plastid division proteins FtsZ1 and FtsZ2 and identification of ARC6 and ARC3 in a native FtsZ complex ». Biochemical Journal 412, n^o 2 (14 mai 2008) : 367–78. http://dx.doi.org/10.1042/bj20071354.

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FtsZ1 and FtsZ2 are phylogenetically distinct homologues of the tubulin-like bacterial cell division protein FtsZ that play major roles in the initiation and progression of plastid division in plant cells. Both proteins are components of a mid-plastid ring, the Z-ring, which functions as a contractile ring on the stromal surface of the chloroplast IEM (inner envelope membrane). FtsZ1 and FtsZ2 have been shown to interact, but their in vivo biochemical properties are largely unknown. To gain insight into the in vivo biochemical relationship between FtsZ1 and FtsZ2, in the present study we investigated their molecular levels in wild-type Arabidopsis thaliana plants and endogenous interactions in Arabidopsis and pea. Quantitative immunoblotting and morphometric analysis showed that the average total FtsZ concentration in chloroplasts of 3-week-old Arabidopsis plants is comparable with that in Escherichia coli. FtsZ levels declined as plants matured, but the molar ratio between FtsZ1 and FtsZ2 remained constant at approx. 1:2, suggesting that this stoichiometry is regulated and functionally important. Density-gradient centrifugation, native gel electrophoresis, gel filtration and co-immunoprecipitation experiments showed that a portion of the FtsZ1 and FtsZ2 in Arabidopsis and pea chloroplasts is stably associated in a complex of ∼200–245 kDa. This complex also contains the FtsZ2-interacting protein ARC6 (accumulation and replicatioin of chloroplasts 6), an IEM protein, and analysis of density-gradient fractions suggests the presence of the FtsZ1-interacting protein ARC3. Based on the mid-plastid localization of ARC6 and ARC3 and their postulated roles in promoting and inhibiting chloroplast FtsZ polymer formation respectively, we hypothesize that the FtsZ1–FtsZ2–ARC3–ARC6 complex represents an unpolymerized IEM-associated pool of FtsZ that contributes to the dynamic regulation of Z-ring assembly and remodelling at the plastid division site in vivo.

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Shaik, Rahamthulla S., Min Woo Sung, Stanislav Vitha et Andreas Holzenburg. « Chloroplast division protein ARC3 acts on FtsZ2 by preventing filament bundling and enhancing GTPase activity ». Biochemical Journal 475, n^o 1 (2 janvier 2018) : 99–115. http://dx.doi.org/10.1042/bcj20170697.

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Chloroplasts evolved from cyanobacterial endosymbiotic ancestors and their division is a complex process initiated by the assembly of cytoskeletal FtsZ (Filamentous temperature sensitive Z) proteins into a ring structure at the division site (Z-ring). The cyanobacterial Z-ring positioning system (MinCDE proteins) is also conserved in chloroplasts, except that MinC was lost and replaced by the eukaryotic ARC3 (accumulation and replication of chloroplasts). Both MinC and ARC3 act as negative regulators of FtsZ assembly, but ARC3 bears little sequence similarity with MinC. Here, light scattering assays, co-sedimentation, GTPase assay and transmission electron microscopy in conjunction with single-particle analysis have been used to elucidate the structure of ARC3 and its effect on its main target in chloroplast division, FtsZ2. Analysis of FtsZ2 in vitro assembly reactions in the presence and absence of GMPCPP showed that ARC3 promotes FtsZ2 debundling and disassembly of existing filaments in a concentration-dependent manner and requires GTP hydrolysis. Three-dimensional reconstruction of ARC3 revealed an almost circular molecule in which the FtsZ-binding N-terminus and the C-terminal PARC6 (paralog of ARC6)-binding MORN (Membrane Occupation and Recognition Nexus) domain are in close proximity and suggest a model for PARC6-enabled binding of ARC3 to FtsZ2. The latter is corroborated by in vivo data.

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KUROBOSHI, M., N. YAMADA, Y. TAKEBE et T. HIYAMA. « ChemInform Abstract : Stereoselective Synthesis of (E)-ArCF=CFR and (E)-ArCH=CFR from ArCH( OH)CFBr2. » ChemInform 26, n^o 50 (16 août 2010) : no. http://dx.doi.org/10.1002/chin.199550068.

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Bekker, Martijn, Svetlana Alexeeva, Wouter Laan, Gary Sawers, Joost Teixeira de Mattos et Klaas Hellingwerf. « The ArcBA Two-Component System of Escherichia coli Is Regulated by the Redox State of both the Ubiquinone and the Menaquinone Pool ». Journal of Bacteriology 192, n^o 3 (20 novembre 2009) : 746–54. http://dx.doi.org/10.1128/jb.01156-09.

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ABSTRACT ArcBA is a two-component regulatory system of Escherichia coli involved in sensing oxygen availability and the concomitant transcriptional regulation of oxidative and fermentative catabolism. Based on in vitro data, it has been postulated that the redox state of the ubiquinone pool is the determinant for ArcB kinase activity. Here we report on the in vivo regulation of ArcB activation, as determined using a lacZ reporter specifically responsive to phosphorylated ArcA. Our results indicate that upon deletion of a ubiquinone biosynthetic enzyme, regulation of ArcB in the anaerobic-aerobic transition is not affected. In contrast, interference with menaquinone biosynthesis leads to inactivation of ArcB during anaerobic growth; this phenotype is fully rescued by addition of a menaquinone precursor. This clearly demonstrates that the menaquinones play a major role in ArcB activation. ArcB shows a complex pattern of regulation when E. coli is titrated through the entire aerobiosis range; ArcB is activated under anaerobic and subaerobic conditions and is much less active under fully aerobic and microaerobic conditions. Furthermore, there is no correlation between ArcB activation and the redox state of the ubiquinone pool, but there is a restricted correlation between the total cellular ubiquinone content and ArcB activity due to the considerable increase in the size of the ubiquinone pool with increasing degrees of aerobiosis. These results lead to the working hypothesis that the in vivo activity of ArcB in E. coli is modulated by the redox state of the menaquinone pool and that the ubiquinone/ubiquinol ratio in vivo surely is not the only determinant of ArcB activity.

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Farré, Judith. « La entrada del marqués de las Amarillas en Puebla (1755), iconografía y sermón «políticogratulatorio» ». Nuevas de Indias. Anuario del CEAC 6 (31 décembre 2021) : 18–53. http://dx.doi.org/10.5565/rev/nueind.87.

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Este trabajo estudia la entrada en Puebla del marqués de las Amarillas (1755) como virrey de Nueva España. El programa iconográfico del arco para la entrada en la catedral poblana corrió a cargo del canónigo magistral, el predicador Andrés de Arce y Miranda. No se conserva el impreso con la idea explicativa pero aquí se analiza a partir del lienzo depositado en el Fondo Guillermo Tovar de Teresa de la Col. Museo Soumaya-Fundación Carlos Slim de la Ciudad de México y, como novedad, en correlación al sermón que el propio Arce predicó en la Catedral el 29 de octubre como homenaje y recibimiento al virrey: «Conservar en paz un Reino».

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Draesner, Ulrike, et Martha Kosir-Widenbauer. « bahn ubern bogen / el tranvia sobre un arco / track over arch ». Sirena : poesia, arte y critica 2005, n^o 2 (2005) : 28–31. http://dx.doi.org/10.1353/sir.2005.0058.

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Żyła, Tomasz, Beata Kawala, Rafał Nowak, Maciej Kawala et Jowita Halupczok-Żyła. « Three-Dimensional Cephalometric Analysis of Skeletal and Dental Effects in Patients Undergoing Transpalatal Distraction ». Applied Sciences 12, n^o 9 (23 avril 2022) : 4273. http://dx.doi.org/10.3390/app12094273.

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The present study aimed to assess dental and skeletal effects after transpalatal distraction using 3D cephalometry methodology. The study group comprised 34 patients (mean age 27.7 years) who were diagnosed with transverse skeletal maxillary deficiency of at least 7 mm. Computed tomography scans were obtained before surgical procedure (T1), after completion of expansion (T2) and at 6-month follow-up (T3). Computed tomography scans were imported into Dolphin Imaging software version 11.7 (Chatsworth, CA, USA). Three-dimensional skull models were oriented according to the Frankfurt horizontal plane, midsagittal plane (passing through the skeletal nasion) and frontal plane (passing through the right and left porion). Cephalometric landmarks related to skeletal, and dental structures were traced and linear and angular measurements were calculated. Following transpalatal distraction N-ANS and S-PNS distances increased by 1.27 mm and 0.54 mm, respectively. Skeletal expansion at the canine region (ARCR-ARCL) was 8.43 mm at T2 and 6.39 mm at T3. Expansion at the distal part of the maxilla (ARMR-ARML) was 5.95 mm at T2 and 4.81 mm after retention. The highest increase in maxillary arch width at T2 was observed at canines (8.74 mm), lower at premolars (8.33 mm) and the lowest at molars (6.76 mm). There is no anteroposterior movement of maxilla following transpalatal distraction; however, the maxilla shifts downward which is particularly marked anteriorly. Skeletal and dental expansion in the transversal plane occurs in a V-shaped manner, with more expansion at the anterior part of the maxilla.

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Piovesan, Martina Gonçalves, Henrique Hiroto Naoe, Niége Michelle Lazzari de Onofre, José Gonçalves de Oliveira Filho et Tanara Prux Fehlberg. « Utilização do arco de Connecticut (CIA®) para intrusão dos dentes anteriores – relato de caso ». Orthodontic Science and Practice 15, n^o 57 (2022) : 62–70. http://dx.doi.org/10.24077/2022;1557-1828467.

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A sobremordida profunda é uma má oclusão vertical que pode apresentar um conjunto de características esqueléticas, dentárias e neuromusculares que produzem uma quantidade excessiva de trespasse vertical na região dos incisivos. O tratamento da sobremordida pode ser realizado pela extrusão dos dentes posteriores, distalização dos dentes posteriores, inclinação vestibular dos dentes anteriores (com intrusão relativa) e intrusão real dos incisivos superiores e/ ou inferiores. Existem diferentes técnicas para tratamento da sobremordida, entretanto, muitas destas apresentam efeitos adversos decorrentes do tipo de mecânica aplicada. O arco Connecticut Intrusion Arch CIA® é um arco de intrusão que possui dobra em “V” pré-calibrada na região posterior, que é confeccionada com o alicate nº 291 (Zattyr®), proporcionando forças de intrusão adequadas (leve e contínua). O objetivo do trabalho foi realizar revisão de literatura sobre o arco CIA®, no qual foi descrito: definição, aplicabilidade, vantagens e desvantagens. Foi realizado um passo a passo da técnica de confecção deste arco e demonstrada sua aplicação em um caso clí- nico. O arco de intrusão, confeccionado de forma simples e padronizada, foi efetivo na intrusão dos incisivos e no controle mecânico vertical e sagital no sistema straight wire do caso clínico apresentado e de acordo com os resultados que foram encontrados na revisão de literatura.

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Zúñiga, Manuel, María del Carmen Miralles et Gaspar Pérez-Martínez. « The Product of arcR, the Sixth Gene of the arc Operon of Lactobacillus sakei, Is Essential for Expression of the Arginine Deiminase Pathway ». Applied and Environmental Microbiology 68, n^o 12 (décembre 2002) : 6051–58. http://dx.doi.org/10.1128/aem.68.12.6051-6058.2002.

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ABSTRACT Lactobacillus sakei is a lactic acid bacterium commonly used as a starter culture for dry sausage production and can utilize arginine via the arginine deiminase pathway. The arcABCTD cluster of L. sakei has been characterized, and transcriptional studies have shown that its expression is subject to carbon catabolite repression and induction by arginine. Downstream of arcD an additional gene has been found; this gene, arcR, codes for a putative regulatory protein of the Crp/Fnr family. Transcriptional studies have shown that arcR is coordinately transcribed with the remaining arc genes, and therefore, these genes constitute the arcABCTDR operon. Northern analysis also showed a complex pattern of transcripts, suggesting that processing and partial termination may play a role in regulation of the expression of individual genes of the operon. Inactivation of arcR led to arrest of transcription of the operon, indicating that the ArcR protein is essential for expression of the arc genes. The availability of this mutant made it possible to study whether the ability to utilize arginine affects the growth of L. sakei in meat fermentations. Under our experimental conditions, expression of arginine deiminase does not confer an obvious advantage to L. sakei, since the wild type and an arcR mutant strain displayed similar dynamics of growth.

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