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Literatura académica sobre el tema "F plasmid"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 1 de febrero de 2022

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Artículos de revistas sobre el tema "F plasmid"

Lin, Mei-Hui, and Shih-Tung Liu. "Stabilization of pSW100 from Pantoea stewartii by the F Conjugation System." Journal of Bacteriology 190, no. 10 (2008): 3681–89. http://dx.doi.org/10.1128/jb.00846-07.

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ABSTRACT Plasmid pSW100 is 1 of the 13 plasmids from Pantoea stewartii subsp. stewartii SW2 which has a replicon that resembles that of ColE1. This work uses a pSW100 derivative, pSW140K, to study how the pSW100 replicon is stably maintained in its hosts. Our results indicate that although pSW140K is stable in Escherichia coli HB101, the plasmid is rapidly lost in another E. coli strain, DH5α, indicating that the genetic background of an E. coli strain affects the stability of pSW140K. Mutagenesis of E. coli HB101 with EZ::TN <DHFR-1> revealed that mutations in traC, traF, traG, traN, and traV, which encode the components of the sex pilus assembly, reduce plasmid stability. Furthermore, this work identified that a 38-bp region located immediately upstream of the RNAII promoter is critical to the maintenance of plasmid stability in E. coli HB101. TraC binds to the region, and in addition, deleting the region destabilizes the plasmid. Furthermore, inserting this 38-bp fragment into a plasmid that contains the minimal replicon from pSW200 stabilizes the plasmid in E. coli HB101. Fluorescence in situ hybridization and immunofluorescence staining also revealed that derivatives of pSW100, pSW128A, and TraC are colocalized in cells, suggesting that pSW100 may use the sex pilus assembly as a partition apparatus to ensure the even distribution of the plasmid during cell division, which may thus maintain the plasmid's stability.

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Matlock, William, Kevin K. Chau, Manal AbuOun, et al. "Genomic network analysis of environmental and livestock F-type plasmid populations." ISME Journal 15, no. 8 (2021): 2322–35. http://dx.doi.org/10.1038/s41396-021-00926-w.

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AbstractF-type plasmids are diverse and of great clinical significance, often carrying genes conferring antimicrobial resistance (AMR) such as extended-spectrum β-lactamases, particularly in Enterobacterales. Organising this plasmid diversity is challenging, and current knowledge is largely based on plasmids from clinical settings. Here, we present a network community analysis of a large survey of F-type plasmids from environmental (influent, effluent and upstream/downstream waterways surrounding wastewater treatment works) and livestock settings. We use a tractable and scalable methodology to examine the relationship between plasmid metadata and network communities. This reveals how niche (sampling compartment and host genera) partition and shape plasmid diversity. We also perform pangenome-style analyses on network communities. We show that such communities define unique combinations of core genes, with limited overlap. Building plasmid phylogenies based on alignments of these core genes, we demonstrate that plasmid accessory function is closely linked to core gene content. Taken together, our results suggest that stable F-type plasmid backbone structures can persist in environmental settings while allowing dramatic variation in accessory gene content that may be linked to niche adaptation. The association of F-type plasmids with AMR may reflect their suitability for rapid niche adaptation.

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Boyd, E. Fidelma, Charles W. Hill, Stephen M. Rich, and Daniel L. Hartl. "Mosaic Structure of Plasmids From Natural Populations of Escherichia coli." Genetics 143, no. 3 (1996): 1091–100. http://dx.doi.org/10.1093/genetics/143.3.1091.

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Abstract The distribution of plasmids related to the fertility factor F was examined in the ECOR reference collection of Escherichia coli. Probes specific for four F-related genes were isolated and used to survey the collection by DNA hybridization. To estimate the genetic diversity of genes in F-like plasmids, DNA sequences were obtained for four plasmid genes. The phylogenetic relationships among the plasmids in the ECOR strains is very different from that of the strains themselves. This finding supports the view that plasmid transfer has been frequent within and between the major groups of ECOR. Furthermore, the sequences indicate that recombination between genes in plasmids takes place at a considerably higher frequency than that observed for chromosomal genes. The plasmid genes, and by inference the plasmids themselves, are mosaic in structure with different regions acquired from different sources. Comparison of gene sequences from a variety of naturally occurring plasmids suggested a plausible donor of some of the recombinant regions as well as implicating a chi site in the mechanism of genetic exchange. The relatively high rate of recombination in F-plasmid genes suggests that conjugational gene transfer may play a greater role in bacterial population structure than previously appreciated.

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Haake, Susan Kinder, Sean C. Yoder, Gwynne Attarian, and Kara Podkaminer. "Native Plasmids of Fusobacterium nucleatum: Characterization and Use in Development of Genetic Systems." Journal of Bacteriology 182, no. 4 (2000): 1176–80. http://dx.doi.org/10.1128/jb.182.4.1176-1180.2000.

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ABSTRACT Three native plasmids of Fusobacterium nucleatum were characterized, including DNA sequence analysis of one plasmid, pFN1. A shuttle plasmid, pHS17, capable of transforming Escherichia coli and F. nucleatum ATCC 10953 was constructed with pFN1. pHS17 was stably maintained in the F. nucleatum transformants, and differences in the transformation efficiencies suggested the presence of a restriction-modification system in F. nucleatum.

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May, Thithiwat, and Satoshi Okabe. "Escherichia coli Harboring a Natural IncF Conjugative F Plasmid Develops Complex Mature Biofilms by Stimulating Synthesis of Colanic Acid and Curli." Journal of Bacteriology 190, no. 22 (2008): 7479–90. http://dx.doi.org/10.1128/jb.00823-08.

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ABSTRACT It has been shown that Escherichia coli harboring the derepressed IncFI and IncFII conjugative F plasmids form complex mature biofilms by using their F-pilus connections, whereas a plasmid-free strain forms only patchy biofilms. Therefore, in this study we investigated the contribution of a natural IncF conjugative F plasmid to the formation of E. coli biofilms. Unlike the presence of a derepressed F plasmid, the presence of a natural IncF F plasmid promoted biofilm formation by generating the cell-to-cell mating F pili between pairs of F+ cells (approximately two to four pili per cell) and by stimulating the formation of colanic acid and curli meshwork. Formation of colanic acid and curli was required after the initial deposition of F-pilus connections to generate a three-dimensional mushroom-type biofilm. In addition, we demonstrated that the conjugative factor of F plasmid, rather than a pilus synthesis function, was involved in curli production during biofilm formation, which promoted cell-surface interactions. Curli played an important role in the maturation process. Microarray experiments were performed to identify the genes involved in curli biosynthesis and regulation. The results suggested that a natural F plasmid was more likely an external activator that indirectly promoted curli production via bacterial regulatory systems (the EnvZ/OmpR two-component regulators and the RpoS and HN-S global regulators). These data provided new insights into the role of a natural F plasmid during the development of E. coli biofilms.

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Haryanto, Aris, Hevi Wihadmadyatami, and Nastiti Wijayanti. "In vitro expression of the recombinant fusion protein of Newcastle disease virus from local Indonesian isolates by using a cell-free protein expression system." Indonesian Journal of Biotechnology 25, no. 2 (2020): 69. http://dx.doi.org/10.22146/ijbiotech.54703.

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The aim of this work was the in vitro expression of the recombinant fusion (F) protein of Newcastle disease virus (NDV). The pBT7-N-His-Fusion-NDV expression plasmid which carries the recombinant F protein encoding gene from local Indonesian isolates, was prepared and transformed into E. coli BL21 (DE3). To detect bacterial colonies carrying the recombinant plasmid, a restriction endonuclease analysis was performed using the EcoRI restriction endonuclease. These results showed that the pBT-N-His-Fusion-NDV plasmid was successfully isolated with a size of 4.601 bp, and three recombinant plasmids carrying the gene coding for the recombinant F protein of NDV were obtained. Selected recombinant plasmids were then in vitro by using a cell-free protein expression system followed by visualization of the recombinant F protein on a 12% SDS-PAGE gel both by Coomassie Brilliant Blue staining and Western blotting. Recombinant F protein was successfully in vitro expressed by using a cell-free protein expression system as indicated by a specific single protein band with a molecular mass of 25.6 kDa.

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Boyd, E. Fidelma, and Daniel L. Hartl. "Salmonella Virulence Plasmid: Modular Acquisition of the spv Virulence Region by an F-Plasmid in Salmonella enterica Subspecies I and Insertion Into the Chromosome of Subspecies II, IIIa, IV and VII Isolates." Genetics 149, no. 3 (1998): 1183–90. http://dx.doi.org/10.1093/genetics/149.3.1183.

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Abstract The spv operon is common to all Salmonella virulence plasmids. DNA hybridization analysis indicates that the spv region is limited in distribution to serovars of Salmonella enterica subspecies I, II, IIIa, IV, and VII and is absent from Salmonella bongori isolates. Among strains of subspecies II, IIIa, and VII, all isolates examined contained sequences that hybridized with the spv region. However, among isolates of subspecies I, DNA sequences capable of hybridizing with the spv region were found in some isolates of certain serovars. Furthermore, in isolates of subspecies I, the virulence plasmid was found in the same set of isolates as an F-related plasmid, as determined by the presence of the spv region of the virulence plasmid and the finO, traD, and repA sequences of the F-plasmid. The concordance of the virulence plasmid and all three F-plasmid sequences in subspecies I serovar Choleraesuis, Paratyphi, and Typhimurium is most easily explained if the spv region is carried in an F-related plasmid in these isolates. In contrast, among S. enterica subspecies II, IIIa, IV, and VII, the isolates that contain spv sequences did not hybridize with an F-related plasmid or any other identifiable plasmid. With the use of pulse-field gel electrophoresis, the spv region in subspecies II, IIIa, and VII was found to be encoded on the chromosome. Analysis of the phylogenetic distribution of spv among Salmonella isolates and comparative nucleotide sequence analysis of spvA and spvC suggests that the spv region was acquired very recently, after speciation of the salmonellae.

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Dostál, Lubomír, Sichen Shao, and Joel F. Schildbach. "Tracking F plasmid TraI relaxase processing reactions provides insight into F plasmid transfer." Nucleic Acids Research 39, no. 7 (2010): 2658–70. http://dx.doi.org/10.1093/nar/gkq1137.

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Hammerl, Jens A., Iris Klein, Erich Lanka, Bernd Appel, and Stefan Hertwig. "Genetic and Functional Properties of the Self-Transmissible Yersinia enterocolitica Plasmid pYE854, Which Mobilizes the Virulence Plasmid pYV." Journal of Bacteriology 190, no. 3 (2007): 991–1010. http://dx.doi.org/10.1128/jb.01467-07.

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ABSTRACT Yersinia strains frequently harbor plasmids, of which the virulence plasmid pYV, indigenous in pathogenic strains, has been thoroughly characterized during the last decades. Yet, it has been unknown whether the nonconjugative pYV can be transferred by helper plasmids naturally occurring in this genus. We have isolated the conjugative plasmids pYE854 (95.5 kb) and pYE966 (70 kb) from a nonpathogenic and a pathogenic Yersinia enterocolitica strain, respectively, and demonstrate that both plasmids are able to mobilize pYV. The complete sequence of pYE854 has been determined. The transfer proteins and oriT of the plasmid reveal similarities to the F factor. However, the pYE854 replicon does not belong to the IncF group and is more closely related to a plasmid of gram-positive bacteria. Plasmid pYE966 is very similar to pYE854 but lacks two DNA regions of the larger plasmid that are dispensable for conjugation.

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Dionisio, Francisco, Ivan Matic, Miroslav Radman, Olivia R. Rodrigues, and François Taddei. "Plasmids Spread Very Fast in Heterogeneous Bacterial Communities." Genetics 162, no. 4 (2002): 1525–32. http://dx.doi.org/10.1093/genetics/162.4.1525.

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Abstract Conjugative plasmids can mediate gene transfer between bacterial taxa in diverse environments. The ability to donate the F-type conjugative plasmid R1 greatly varies among enteric bacteria due to the interaction of the system that represses sex-pili formations (products of finOP) of plasmids already harbored by a bacterial strain with those of the R1 plasmid. The presence of efficient donors in heterogeneous bacterial populations can accelerate plasmid transfer and can spread by several orders of magnitude. Such donors allow millions of other bacteria to acquire the plasmid in a matter of days whereas, in the absence of such strains, plasmid dissemination would take years. This “amplification effect” could have an impact on the evolution of bacterial pathogens that exist in heterogeneous bacterial communities because conjugative plasmids can carry virulence or antibiotic-resistance genes.

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Tesis sobre el tema "F plasmid"

Kennedy, Martin A. "Transcriptional promoters in a replication region of F plasmid." Thesis, University of Auckland, 1986. http://hdl.handle.net/2292/2482.

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This thesis describes aspects of genetic regulation within and near a replication origin (ori-1) of the F plasmid. A number of transcriptional promoters were isolated, precisely mapped, and characterized with respect to their strengths and modes of regulation. The principal techniques employed in these investigations were: "shotgun" molecular cloning of restriction fragments into a galactokinase-based promoter selection vector, assays for galactokinase activities, DNA sequencing and S1 nuclease mapping of transcripts. Major findings from this study can be summarized as follows: 1). Promoters for the essential replication genes pifC and E were cloned and shown to be autoregulated at the transcriptional level. 2). An E.coli protein, integration host factor (IHF), was found to modulate the activity of the pif operon promoter. 13). Two promoters which direct transcription in opposite directions from within the minimal ori-1 region were discovered. 4). Transcription from both ori-1 promoters was shown to be repressed by the mini-F encoded D protein. 5). Precise transcriptional startsites of the pifC gene and the two ori-1 promoters were determined. 6). A mini-F protein (D) was shown to resolve dimers of a plasmid which contains a site-specific recombination locus from near ori-1, and a facile assay system for this function was developed.

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Hyde, Helena. "F-mediated mobilisation and stability of the plasmid NTP16." Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257206.

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Kosuk, Nicholas L. "Topological analysis of the F plasmid encoded TraD protein /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/10244.

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Anthony, Karen Gnanammal. "Role of the pilus in F plasmid-mediated bacterial conjugation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ34727.pdf.

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Nakamura, Akira. "Structural studies on replication initiator protein RepE of F plasmid." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136792.

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Fekete, Richard Alfred. "Characterizing the protein and DNA interactions of the F plasmid DNA binding protein, TraM." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ60291.pdf.

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Goldschmidt, Gunther Karl. "Cloning, Sequencing and Partial Characterization of the Accessory Gene Region of Plasmid pTC-F14 isolated from the Biomining Bacterium Acidithiobacillus caldus f." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/1588.

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Thesis (MSc (Microbiology))--University of Stellenbosch, 2005.<br>Plasmid pTC-F14 is a 14.2kb promiscuous, broad-host range IncQ-like mobilizable plasmid isolated from Acidithiobacillus caldus f. At. caldus is a member of a consortium of bacteria (along with Acidithiobacillus ferrooxidans and Leptospirilum ferrooxidans) that is used industrially for decomposing metal sulphide ores and concentrates at temperatures of 40ºC or below which is now a well-established industrial process to recover metals from certain copper, uranium and gold-bearing minerals or mineral concentrates. These biomining microbes are usually obligately acidophilic, autotrophic, usually aerobic iron- or sulphur-oxidizing chemolithotrophic bacteria. Their remarkable physiology allows them to inhabit an ecological niche that is largely inorganic and differs from those environments populated by the more commonly studied non-acidophilic heterotrophic bacteria. At. caldus, is a moderately thermophilic (45 to 50ºC), highly acidophilic (pH1.5 to 2.5) sulphur-oxidizing bacterium, and its role as one of the major players in the industrial decomposition of metal sulphide ores has become evident in recent years. At. caldus f from which pTC-F14 was isolated was found to be one of two dominant organisms in a bacterial consortium undergoing pilot-scale testing for the commercial extraction of nickel from ores.

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Sommer, Suzanne. "Induction des fonctions SOS par introduction d'ADN exogène." Paris 11, 1987. http://www.theses.fr/1987PA112120.

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Les bactéries réagissent aux traitements qui endommagent l'ADN par l'induction d'un ensemble de gènes dits "SOS". L'induction des gènes SOS résulte de l'inactivation du répresseur LexA par une forme activée de la protéine RecA. Quand la réplication de l'ADN est bloquée, un signal appelé signal SOS permet l'activation de la protéine RecA. 1- Pour déterminer la nature et les mécanismes de formation du signal SOS, nous avons introduit dans des cellules intactes des réplicons endommagés et/ou bloqués dans leur réplication. Nos résultats montrent que le signal SOS est constitué par des portions d'ADN simple-brin sur un réplicon, le signal induit par le plasmide miniF étant localisé en trans sur le chromosome bactérien, celui qui est engendré par le plasmide F ou l'ADN Hfr étant situé en cis sur l’ADN transféré. Nos résultats infirment l'hypothèse selon laquelle l’activation de la protéine RecA serait due à des oligonucléotides résultant de la dégradation de l’ADN. 2- Nous avons caractérisé les fonctions des polypeptides PsiA et PsiB codés par le plasmide R6. 5. L'expression des gènes psiA et psiB a un effet pléiotrope sur la cellule, inhibant à la fois l'induction des fonctions SOS et la recombinaison génétique. Nous pensons que les protéines PsiA et PsiB agissent à la fourche de réplication du chromosome bactérien<br>Bacteria react to treatments that damage DNA by induction of a set of genes called "SOS genes". The induction of the SOS genes results from the inactivation of the LexA repressor by an activated form of RecA protein. When DNA replication is blocked, a signal, called "SOS signal" permits the activation of RecA protein. 1- To determine the nature and the mechanisms of formation of the SOS signal, we have introduced into intact cells replicons damaged or blocked in their replication. Our findings are consistent with a picture where the SOS signal is constituted by stretches of single-stranded DNA on a replicon. The SOS signal induced by miniF plasmid is located in trans on the host chromosome, the one generated by F or Hfr DNA is located in cis on the transferred DNA. Our results argue against the hypothesis that activation of RecA protein is promoted by oligonucleotides resulting from DNA degradation. 2- We have characterized the functions of the polypeptides PsiA and PsiB coded by plasmid R6. 5. The expression of psiA and psiB genes has a pleiotropic effect on the cell, counteracting induction of SOS functions and genetic recombination. We postulate that PsiA and PsiB proteins act on the replication fork of the bacterial chromosome

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Ah-Seng, Yoan. "La Ségrégation du plasmide F d'Escherichia coli : régulation de l'activité ATPase de la protéine moteur de partition SopA." Toulouse 3, 2010. http://thesesups.ups-tlse.fr/1126/.

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La ségrégation, ou partition, des chromosomes et des plasmides bactériens est l'étape fondamentale du cycle cellulaire qui assure la transmission de l'ensemble du génome aux cellules filles. C'est l'équivalent procaryote de la mitose. Des systèmes de ségrégation, appelés les loci par, ont été identifiés sur les plasmides à bas nombre de copies, et des homologues de ces systèmes de partition sont présents sur la majorité des chromosomes bactériens. Le système code deux protéines, une ATPase et une protéine qui se fixe spécifiquement sur une région centromérique. Ces deux protéines interagissent entre elles, permettent la localisation subcellulaire des réplicons et assurent ainsi leur maintien dans les générations futures. Au laboratoire, nous étudions l'un des systèmes modèles majeurs, le système de partition du plasmide F d'Escherichia coli, afin de déterminer le mécanisme moléculaire assurant le processus de ségrégation et son contrôle pendant le cycle cellulaire. La stabilité du plasmide F est assurée par le système de partition sopABC. Après la réplication du plasmide, la protéine SopB s'assemble sur le centromère sopC pour former un complexe de partition qui permet aux copies du plasmide d'être positionnés au centre de la cellule. Avant la division cellulaire les plasmides migrent aux positions 1/4 et 3/4 de la cellule et assurent ainsi l'héritage des réplicons dans les futures cellules filles. L'ATPase SopA est essentielle dans le processus de partition, mais son rôle n'est pas bien défini. SopA pourrait être impliquée dans les étapes de positionnement et/ou de déplacement des plasmides de part et d'autre de la cellule. SopA possède plusieurs activités. In vivo, SopA agit comme autorépresseur de l'opéron sopAB en se fixant sur la région promotrice. De plus elle interagit avec le complexe de partition et forme des polymères en présence d'ATP. Nous avons montré que cette activité est régulée par SopB et par l'ADN. L'activité ATPase de SopA est essentielle pour la partition. Elle est légèrement stimulée par SopB et par l'ADN, mais lorsque ces deux facteurs sont présents, elle est fortement stimulée. Nous avons entrepris de caractériser les interactions existantes entre ces trois protagonistes. Ainsi, nous avons démontré que cette stimulation nécessite une interaction de SopA avec SopB d'une part et avec l'ADN d'autre part. Nous avons également montré que le site centromérique sopC potentialise la stimulation de l'activité ATPase par l'intermédiaire de SopB. Nous nous sommes intéressés ensuite à l'interaction SopA-SopB, et nous avons mis en évidence que SopB stimule l'activité ATPase de SopA via un motif arginine finger. Pour finir, nous avons montré que in vivo, la stimulation de l'activité ATPase de SopA joue un rôle dans la régulation de l'opéron sopAB mais aussi dans la partition du plasmide F<br>Mitotic segregation of chromosomes and plasmids, termed partition in bacteria, is a fundamental step of the cell cycle that ensures the transmission of the whole genome to daughter cells. It is governed by specific genetic loci named par, first identified in low copy number plasmids and later found to be present as homologues in most bacterial chromosomes. Par loci encode two proteins, an ATPase and a DNA binding protein, and include a cis-acting centromeric site. These components interact with each other to direct the subcellular localization that ensures stability of their replicons. To determine the molecular mechanisms of the partition process and its control during the cell cycle, we study the Sop partition system of the Escherichia coli plasmid, F. Sop is one of the best-known partition systems. After F plasmid replication, SopB protein binds to the sopC centromeric site to form a partition complex. The complex on each plasmid copy interacts with SopA, an ATPase, and activates it to move the plasmid molecules towards the two cell poles. SopA ATPase is essential to the segregation process but its role is not defined. SopA has many activities. In vivo it represses its own operon by binding to the sopAB promoter. Moreover, in addition to its interaction with the partition complex it polymerizes in the presence of ATP. We have shown that SopB and DNA regulate this activity. Although the ATP-binding site on SopA is essential for partition, ATP hydrolysis by SopA is very weak. It is stimulated modestly by DNA and by SopB and strongly in the presence of both. We have characterized the interactions necessary for stimulation of ATP hydrolysis. First we found that the SopB-sopC partition complex is required for maximal stimulation. Then we showed that SopB and DNA contact SopA by two distinct interactions to fully activate ATPase activity. We also found that SopB activates SopA ATPase through an arginine finger motif. Finally, we have shown that in vivo, stimulation of the ATPase activity is necessary for both regulation of the sopAB operon and partition of plasmid F to be efficient

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Castaing, Jean-Philippe. "La ségrégation du plasmide F d'Escherichia coli : étude du rôle de la fixation de l'ATPase Sopa à l'ADN." Toulouse 3, 2009. http://thesesups.ups-tlse.fr/597/.

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La ségrégation de l'ADN, appelée partition chez les procaryotes, permet à tout organisme de transmettre son patrimoine génétique au cours des générations. Il existe des systèmes actifs de partition présents sur la majorité des plasmides et des chromosomes bactériens. Ces systèmes sont essentiels pour la ségrégation active des plasmides à bas nombre de copies tel que le plasmide F d'Escherichia coli, étudié au sein de notre équipe. Son système de partition, appelé sop, est composé de deux gènes, sopA et sopB et d'une séquence centromérique sopC. SopB se fixe à sopC pour former le complexe de partition, reconnu par l'ATPase SopA. SopA polymérise en présence d'ATP. Ce comportement pourrait être le " moteur " de la ségrégation des réplicons. Les travaux de notre équipe ont démontré que SopA se fixe de manière ATP-dépendante à l'ADN non spécifique. Cette fixation inhibe la polymérisation de SopA. SopB, de par sa capacité à se fixer à l'ADN non spécifique, contrebalance ainsi cette inhibition. Nous proposons un modèle dans lequel la polymérisation de SopA serait régulée dans la cellule par l'ADN du nucléoïde. En présence du plasmide, SopB, présent à forte concentration autour du complexe de partition, masquerait l'ADN, créant un environnement dans lequel SopA initierait sa polymérisation. Cette régulation de la dynamique de SopA serait nécessaire au processus de partition. Afin d'étayer notre modèle, nous avons recherché un domaine d'interaction à l'ADN dans SopA. Nous avons identifié un mutant ayant perdu sa fixation ATP-dépendante à l'ADN. Seules les activités de SopA dépendante de cette reconnaissance de l'ADN ont été affectées : l'inhibition de la polymérisation, la stimulation de l'activité ATPase basale et la localisation intracellulaire. Cette mutation entraîne aussi une perte majeure de stabilité du plasmide F correspondant. Ceci confirme l'implication de l'ADN du nucléoïde dans la régulation du comportement dynamique de SopA nécessaire à la partition du plasmide F<br>The segregation of the DNA, also called partition for procaryotes, is the process allowing any organisms to transmit its genetic heritage to next generation. In bacteria, mitotic stability of plasmids and many chromosomes depends on replicon-specific systems which comprise a centromere, a centromere-binding protein and an ATPase. We have taken as a model, the low-copy number plasmid F of Escherichia coli. Centromere-binding protein SopB binds to sopC centromere and forms the partition complex. This nucleoproteic complex is recognized by the SopA "Walker-box" ATPase. SopA shares with other partition ATPase the capacity of self assembly in presence of ATP. This dynamic self-assembly would allow active partition during bacterial division. Previous work in our team showed SopA is also able to bind to non specific DNA in an ATP-dependant manner whereby polymerization is inhibited. Indeed, DNA inhibited this polymerization and cause breakdown of pre-formed polymers. SopB counteracted this DNA effect by binding itself to and masking DNA. We had proposed a model in which the polymerization is spacially regulated. Nucleoid DNA prevent inappropriate SopA polymerization but when SopB is present in high concentration, it create a DNA-depleted zone within SopA can initiate polymerization. The regulation of the dynamic behaviour of the "driving" protein of the system would be necessary for the process of partition. To support our model, we looked for a DNA binding domain in SopA. We have found a SopA mutant, defective for ATP dependent DNA binding. Only the activities of SopA dependent on this binding were affected: the inhibition of the polymerisation is abolished, as the stimulation of the ATPase activity and the intracellular localization. Moreover, this mutant is defective for plasmid stabilization. This last result confirms the implication of the nucleoïd DNA in regulation of the dynamic behavior of SopA, which is necessary for the partition of the plasmide F

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Libros sobre el tema "F plasmid"

Al-Bermani, F. G. A. Elasto-plastic large deformation analysis f thin-walled structures. University of Queensland, Dept. of Civil Engineering, 1989.

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Rich, Frederick J. Plasma densities and irregularities at 830 km altitude based on observations during 1979. Space Physics Division, Air Force Geophysics Laboratory, 1986.

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Rich, Frederick J. Plasma densities and irregularities at 830 km altitude based on observations during 1979. Space Physics Division, Air Force Geophysics Laboratory, 1986.

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M, Filippov V. Konvekt͡s︡ii͡a︡ plazmy v subavroralʹnoĭ zone. I͡A︡kutskiĭ nauch. t͡s︡entr SO RAN, 1996.

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F**k Plastik. Prószyński i S-ka, 2019.

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F**k Plastic: 101 Ways to Free Yourself from Plastic and Save the World. Orion Publishing Group, Limited, 2018.

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F**k Plastic: 101 Ways to Free Yourself from Plastic and Save the World. Potter/TenSpeed/Harmony/Rodale, 2019.

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Schindler, Thomas E. A Hidden Legacy. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780197531679.001.0001.

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This biography of Esther Zimmer Lederberg highlights the importance of her research work, which revealed the unique features of bacterial sex, essential for our understanding of molecular biology and evolution. A Hidden Legacy relates how, she and her husband Joshua Lederberg established the new field of bacterial genetics together, in the decade leading up to the discovery of the DNA double helix. Their impressive series of achievements include: the discovery of λ‎ bacteriophage and of the first plasmid, known as the F-factor; the demonstration that viruses carry bacterial genes between bacteria; and the elucidation of fundamental properties of bacterial sex. This successful collaboration earned Joshua the 1958 Nobel Prize, which he shared with two of Esther’s mentors, George Beadle and Edward Tatum. Esther Lederberg’s contributions, however, were overlooked by the Nobel committee, an example of institutional discrimination known as the Matilda Effect. Esther Lederberg should also have been recognized for inventing replica plating, an elegant technique that she originated by re-purposing her compact makeup pad as a kind of ink stamp for conveniently transferring bacterial colonies from one petri dish to another. Instead, the credit for the invention is given to her famous husband, or, at best, to Dr. and Mrs. Lederberg. Within a few years of winning the Nobel Prize, Joshua Lederberg divorced his wife, leaving Esther without a laboratory, cut off from research funding, and facing uncertain employment. In response, she created a new social circle made up of artists and musicians, including a new soulmate. She devoted herself to a close-knit musical ensemble, the Mid-Peninsula Recorder Orchestra, an avocation that flourished for over forty years, until the final days of her life.

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Gravity wave seeding of equatorial plasma bubbles. National Aeronautics and Space Administration, 1997.

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I, Kapusta Joseph, Muller Berndt 1950-, and Rafelski Johann, eds. Quark-gluon plasma: Theoretical foundations : an annotated reprint collection. Elsevier, 2003.

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Más fuentes

Capítulos de libros sobre el tema "F plasmid"

Gooch, Jan W. "F Plasmid." In Encyclopedic Dictionary of Polymers. Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_13787.

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Gooch, Jan W. "F´ Plasmid." In Encyclopedic Dictionary of Polymers. Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_13790.

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Mullineaux, Phil, and Neil Willetts. "Promoters in the Transfer Region of Plasmid F." In Plasmids in Bacteria. Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2447-8_42.

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Hiraga, Sota, Teru Ogura, Hirotada Mori, and Masafumi Tanaka. "Mechanisms Essential for Stable Inheritance of Mini-F Plasmid." In Plasmids in Bacteria. Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2447-8_34.

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Austin, Stuart, and Ann Abeles. "The Partition Functions of P1, P7, and F Miniplasmids." In Plasmids in Bacteria. Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2447-8_18.

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Laine, Susan, Deanna Moore, Pushpa Kathir, and Karin Ippen-Ihler. "Genes and Gene Products Involved in the Synthesis of F-Pili." In Plasmids in Bacteria. Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2447-8_38.

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Birge, Edward A. "Plasmids and Conjugation Systems Other Than F." In Bacterial and Bacteriophage Genetics. Springer New York, 2000. http://dx.doi.org/10.1007/978-1-4757-3258-0_12.

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Lisitsa, Valery S. "Atom in a Magnetic Field and Crossed F-B Fields." In Atoms in Plasmas. Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78726-3_6.

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Smit Sibinga, C. Th, P. C. Das, and S. Seidl. "Discussion: Moderators: F. Peetoom, C.Th. Smit Sibinga." In Plasma Fractionation and Blood Transfusion. Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2631-1_29.

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Dempsey, Walter B. "Key Regulatory Aspects of Transfer of F-Related Plasmids." In Bacterial Conjugation. Springer US, 1993. http://dx.doi.org/10.1007/978-1-4757-9357-4_3.

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Actas de conferencias sobre el tema "F plasmid"

Ibragimov, A. E., D. Yu Garshina, An Kh Baymiev, and O. V. Lastochkina. "Modulation of Triticum aestivum L. tolerance to combined abiotic/biotic stresses by endophytic plant growth promoting bacteria Bacillus subtilis." In РАЦИОНАЛЬНОЕ ИСПОЛЬЗОВАНИЕ ПРИРОДНЫХ РЕСУРСОВ В АГРОЦЕНОЗАХ. Federal State Budget Scientific Institution “Research Institute of Agriculture of Crimea”, 2020. http://dx.doi.org/10.33952/2542-0720-15.05.2020.11.

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Wheat (Triticum aestivum L.) is one of the most important cereal food crops worldwide. Various abiotic and biotic stresses or their combinations lead to crop losses (up to 50-82%) and pose a serious threat to the agricultural industry and food security. Plant growth-promoting endophytic bacteria Bacillus subtilis are considered as a bioactive and eco-friendly strategy for plant protection. Earlier, we have shown B. subtilis 10-4 has a growth-promoting and anti-stress effect on wheat under water deficiency. Here, we investigated the effect of B. subtilis 10-4 and B. subtilis 10-4+salicylic acid (SA) on growth and tolerance of wheat (cv. ‘Omskaya-35’) to combined drought (12%PEG) and Fusarium culmorum. 12%PEG and F. culmorum led to yellowing of leaves (in addition to traces of the root damages). Inoculation with 10-4 and especially 10-4+SA reduced the fusarium development in wheat under drought. Similar effects were revealed for growth parameters. Also, 10-4 (especially 10-4+SA) reduces stress-induced lipid peroxidation (MDA). Such physiological effect may be connected with the ability of strain 10-4 to colonize the internal tissues of host-plant and regulate metabolism from the inside. The obtained construct based on the plasmid pHT01 and the green fluorescent protein (gfp) gene, by which was modified the strain 10-4, will allow revealing the nature of the symbiotic relationships between the strain 10-4 and host-plant. The findings indicate that application B. subtilis 10-4 and its composition with SA may be an effective strategy to increase wheat tolerance to the combined abiotic/biotic stresses.

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Wiesel, M. L., R. Spaethe, J.-M. Freyssinet, et al. "DETECTION AND EFFECTS OF THROMBOMODULIN ACTIVITY IN CRUDE THROMBOPLASTIN PREPARATIONS FROM PLACENTA AND LUNG." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644300.

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The activation of protein C (PC) by thrombin requires the presence of an endothelial membrane cofactor, thrombomodulin (TM). Activated PC (APC) exerts its anticoagulant activity by degrading factors (F) Va and Villa in the presence of phospholipids and of a vitamin K-dependent cofactor, protein S. Tissue factor (TF) is the essential cofactor of factor Vll/VIIain the activation of factor X. TF is synthetized by several cell lines including endothelial cells. Using a specific TM assay, up to 0.85 units of TM activity could be detected in commercial thromboplastin (TP) preparations from human placenta or rabbit or porcine lung, when the amount of TP was adjusted to contain 1 unit of TF activity. Preparations from brain contained very low amounts, if any, of this activity (< 0.02 TM units). In order to evaluate the effects of the presence of TM activity in some TP preparations, the stability of F V and VIII activities was examined after activation of the coagulation system by these TP in various plasmas. PC deficient plasmas, plasmas lacking F V, VIII or IX and immunoadsorbed PC deficient plasma supplemented with purified human PC (5 Ug/ml) were used. After activation with placenta or lung TP, F V and VIII activities were markedly reduced ( ∼ 90 % reduction) in normal and hemophiliac plasmas, whereas they remained high after activation with brain TP. F V and VIII activities were preserved in protein C deficient plasma after activation by all TP preparations. The same decrease of F V and VIII activities was observed after activation of immunoadsorbed PC deficient plasma supplemented with purified PC with placenta or lung TP only. Preincubation of TP from human placenta with antibodies to human TM raised in laying hens abolished the capacity of this preparation to destroy F V activity of PC containing plasmas. These results establish the presence of TM activity in crude thromboplastin preparations from placenta or from lung. Surprisingly, this anti-coagulant activity seems to be absent from brain. TM from placenta or lung extracts is responsible for the degradation of F V and VIII.

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Fair, D. S., H. A. Chapman, C. L. Allen, and R. Yee. "IN VITRO CHARACTERIZATION OF THE PROCQAGULANT ACTIVITY WITHIN THE BRONCHQALVEOLAR COMPARTMENT OF NORMAL HUMAN LUNG." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643846.

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The procoagulant activity (PCA) of the normal human broncho-alveolar (BA) lining layer was examined qualitatively and quantitatively. Unconcentrated, cell-free lavage freshly obtained from normal volunteers clotted whole plasma in 84 ± 20 sec. The PCA was initiated by factor VII (F VII) and tissue factor (TF) complexes as judged by differential activities in various plasmas genetically deficient in single clotting factors and by neutralization of the PCA with antibodies to either F VII or TF. The cell-free fluid contained about 8500 thromboplastin units/mg total protein. The fluid also contained F VII activity estimated by clotting activity to be 2 ng of plasma F VII/ml of lavage fluid or 22 ng/mg total protein compared to 7 ng/mg protein for normal human plasma. Amidolytic activity measurements suggested that the F VTI concentration was 0.57 ng/ml of lavage fluid. Because of the increased amounts of F VII expressed in the lung relative to plasma, we investigated the activation state of the F VII by the ratio of clotting to amidolytic (VIIc/VIIam) activities. The ratio of unfractionated alveolar fluid was about 19, suggesting the presence of the more active two-chain F Vila. However, imnunoblots of concentrated lavage protein revealed only single-chain F VII and 125I-F VII added to the fluid was not converted to 125I-F VIIa. Additional studies showed that the enhanced PCA of lavage fluid F VII over that of plasma was due to a factor (s) in the sedimentable fraction of the lining layer which directly increased the prothrcmbinase activity of exogenous, purified factor Xa and V/Va and phospholipid (PL). Although normal alveolar macrophages express TF and F VTI, we estimate that the cells contribute < 15% of the total PCA within the alveolar compartment. However, these cells are the only suitable PL surface for prothrcmbinase complex formation within the lavage material, suggesting that macrophages are a major site for thrombin formation within alveoli. Thus, it appears the enhanced rates of thrombin formation rather than an increase in the rate of factor Xa generation explain the accelerated clotting times and the high F VIIc/VIIam ratio, and that macrophages may play a significant role in the total PCA output observed in the lung.

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Laurson, Lasse, and Mikko J. Alava. "1/f noise and plastic deformation." In International conference on Statistical Mechanics of Plasticity and Related Instabilities. Sissa Medialab, 2006. http://dx.doi.org/10.22323/1.023.0051.

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Fagundes, P. R. "Equatorial F-Region Plasma Bubbles Studies." In 5th International Congress of the Brazilian Geophysical Society. European Association of Geoscientists & Engineers, 1997. http://dx.doi.org/10.3997/2214-4609-pdb.299.348.

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Abildgaard, U., P. M. Sandset, M. Pettersen, and M. Hultin. "EXTRINSIC PATHWAY INHIBITOR (EPI):A SENSITIVE CHROMOGENIC SUBSTRATE ASSAY DEMONSTRATES THE RELEASE OF EPI TO THE BLOOD AFTER INJECTION OF HEPARIN." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643915.

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Control of the extrinsic pathway has been ascribed to negative feedback or to plasma inhibitors. Sanders et al recently showed that the inhibitor in plasma cooperates with F X in the inhibition of the tissue thromboplastin (TP)-F Vila complex (Blood 1985, _66,204). Our chromogenic substrate (CS) assay for the plasma inhibitors (Dahl PE et al, Thromb Haemost 1982, 48,253) was manipulated and the results confirm the cooperative effect of F Xa and EPI. When 1 ul of heated plasma was incubated with To (1/100 dil) and amounts of F VII and F X similar to tnose in 1 ul of normal plasma, progressive inhibition of TP-F VII was observed. Using higher amount of F X, the activation to F Xa dominated over inhibition of TP-F Vila. With optimal amounts (0.0005 U F VII, 0.0012 U of F X)in a volume of 250 ul, a 50% inhibition of TP-F Vila developed in 10 minutes. Remaining TP-F Vila was determined by adding 0.02 U of F X and, after 10 minutes, the CS S-2222. The A405 value is inversely related to EPI activity of test plasma or plasma fraction. Prior to assay, functional F II, F VII, F IX and F X in test plasma must be abolished, either by BaSo4 adsorption or by heating to 56° for 15 minutes. BaSo4 removes about 35% of EPI, heating about 15%. Antithrombin and heparin effects in the assay are prevented by specific antibodies and polybrene. EPI activity is reduced by phosphlipase C, suggesting lipoprotein nature. EPI is not released by venous occlusion, but following injection of heparin, EPI increases to 150-250% of base values. High EPI values are found in plasma from patients on heparin. We suggest that this increase in EPI contributes to the antithrombotic effect of heparin. Gel filtration sepa rates plasma EPI into 3 distinct peaks. The macromo-lecular peak accounts for more than half the activity in normal plasma. The activity of this peak increases markedly following heparin injection.

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KUROSO, K., S. IKEMATSU, M. HADA, M. FUJIMAKI, and K. FUKUTAKE. "DEVELOPMENT OF A NEW ASSAY METHOD FOR THE DETECTION OF DD/E COMPLEX." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643130.

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A new assay method for the detection of DD/E complex derived from crosslinked fibrin is developed. This assay is performed on a microtitre plate using capture/tag antibody technique, in which the monoclonal antibody against D dimer fragment (DD-3B6, MAbCO) is coated and anti-E fragment polyclonal F(ab)’2 conjugated with horse radish peroxidase is for a tag-anti body. Antigen dilution curve is drawn in the range of 0.01-1.0 pg/ml of purified DD/E complex. DD/E complex can be measured specifically and other high molecular weight derivatives from crosslinked fibrin show a little crossreaction, though fibrinogen and fibrinogen degradation products show no crossreactivities on this assay. D dimer fragment dissociated from DD/E complex after further plasmin digestion is less reactive in this assay, while this type of D dimer can be detected by DIMERTEST-EIA (MAbCO). These data suggest that an early stage of plasmin digestion of crosslinked fibrin can be detected by this method. A trace amount of DD/E complex curculating in plasma from a small thrombus is possibly detected, because this assay gives an excellent high sensitivity with the detection limit of 0.01 jug/ ml. Normal value of plasma DD/E complex (n=50) indicates below 0.12 pg/ml as 90 percentile. Patients with DIC (n=24) show high levels of DD/E complex between 0.6 and 40 g/ml. These elevated levels of DD/E complex may suggest consequently the existence of the plasmic digestion of crosslinked fibrin in the cases with DIC. In summary, it is concluded that the development of this assay will add one technique to discriminate between fibrinolysis and fibrinogenolysis and this assay is useful for the quantitative detection of DD/E complex produced in an early stage of fibrinolysis seen in various thrombotic disorders, and for the evaluation of the efficacy of thrombolytic therapy.

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Murayama, H., and N. U. Bang. "INCORPORATION OF PLASMINOGEN ACTIVATOR INHIBITOR INTO FIBRIN, AN ALTERNATIVE REGULATORY PATHWAY OF FIBRINOLYSIS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644442.

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A plasminogen activator inhibitor (PAI-1) Mj, 50 kd is normally found in plasma at low concentrations. Plasma levels increase sharply upon stimulation of endothelial cells with endotoxin or monokines and activated platelets secrete significant quantities of PAI-1. It is possible that high levels of PAI-1 may be achieved at the local sites of intravascular thrombi. Semipurified PAI-1 was therefore prepared from human platelets to study its affinity for fibrin (F). Approximately 50% PAI-1 adsorbed to F monomer immobilized on sepharose and desorbed under conditions of acidic pH and high ionic strength suggesting hydrogen bonding as the mode of interaction. Wells of 96-well microtiter plates were each coated with 50 yg [125I] plasminogen (P)-free fibrinogen and clotted with thrombin in the presence and absence of different concentrations of PAI-1. After extensive washing of the wells, they were incubated with 5 mU of tissue plasminogen activator (t-PA) and 5 mU of P for 6 h. Appropriate calibration curves utilizing different concentrations of t-PA and different concentrations of PAI-1 added to the supernatant rather than to F established that 8-15% of 21-166 mU PAI-1 incorporated into crosslinked (XL) F or noncrosslinked (NXL) F. Incorporated PAI strikingly inhibited fibrinolysis (FL). Percent inhibition of FL of XL or NXLF (Mean±S.D., N=5) plotted in the presence of 166, 83, 42 and 21 mU of PAI were: 83±3.3, 59.5±1.8, 29.7±5.2 and 15.2±6.14 for XLF and 78±5.3, 31±8.1, 14.5±10.5 and 0 Tor NXL F. As demonstrated by radioautography on SDS PAGE PAI-1 incorporated into F readily formed complexes with [125I] urokinase (u-PA). In these experiments, no evidence for crosslinking of PAI-1 into F has been obtained to date. In experiments utilizing agarose immobilized proteins, it was evident that not only F but also fibrinogen binds PAI-1; PAI-1 associated with F as well as fibrinogen is capable of forming complexes with [1251] u-PA.In contrast, fibronectin, collagen, gelatin and albumin did not bind PAI-1. Thus, PAI-1 in analogy with alpha-2 plasmin inhibitor may modulate physiological fibrinolysis through incorporation into fibrin.

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Castilho, H., Vivian Moreira, José Humberto Andrade; Abdu, Mangalathayil Ali; Arruda, and Daniela Cristina. "ASSOCIATION BETWEEN IONOSPHERIC PLASMA BUBBLES AND SPREAD-F." In 9th International Congress of the Brazilian Geophysical Society. European Association of Geoscientists & Engineers, 2005. http://dx.doi.org/10.3997/2214-4609-pdb.160.sbgf458.

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Castilho, Vivian Moreira, José Humberto Andrade Sobral, Mangalathayil Ali Abdu, and Daniela Cristina Santana Arruda. "ASSOCIATION BETWEEN IONOSPHERIC PLASMA BUBBLES AND SPREAD-F." In 9th International Congress of the Brazilian Geophysical Society & EXPOGEF, Salvador, Bahia, Brazil, 11-14 September 2005. Society of Exploration Geophysicists and Brazilian Geophysical Society, 2005. http://dx.doi.org/10.1190/sbgf2005-458.

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Informes sobre el tema "F plasmid"

Koons, H. C., J. L. Roeder, and P. Rodriguez. Plasma Waves Observed Inside Plasma Bubbles in the Equatorial F Region. Defense Technical Information Center, 1998. http://dx.doi.org/10.21236/ada342736.

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Jarosz, Paul. Plasma Electrolytic Oxidation (PEO) Coatings as Superior Thermal Barriers for Engine Pistons - F. Office of Scientific and Technical Information (OSTI), 2020. http://dx.doi.org/10.2172/1604429.

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Fritts, D. C. Gravity Wave Dynamics and Tidal Interactions in the MLT and at the Bottomside F Layer and Their Potential Contributions to Neutral and Plasma Dynamics. Defense Technical Information Center, 2012. http://dx.doi.org/10.21236/ada559865.

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