Academic literature on the topic 'Flagellen'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Flagellen.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Flagellen"
1
Kanbe, Masaomi, Jin Yagasaki, Susanne Zehner, Michael Göttfert, and Shin-Ichi Aizawa. "Characterization of Two Sets of Subpolar Flagella in Bradyrhizobium japonicum." Journal of Bacteriology 189, no. 3 (November 10, 2006): 1083–89. http://dx.doi.org/10.1128/jb.01405-06.
Full textAbstract:
ABSTRACT Bradyrhizobium japonicum is one of the soil bacteria that form nodules on soybean roots. The cell has two sets of flagellar systems, one thick flagellum and a few thin flagella, uniquely growing at subpolar positions. The thick flagellum appears to be semicoiled in morphology, and the thin flagella were in a tight-curly form as observed by dark-field microscopy. Flagellin genes were identified from the amino acid sequence of each flagellin. Flagellar genes for the thick flagellum are scattered into several clusters on the genome, while those genes for the thin flagellum are compactly organized in one cluster. Both types of flagella are powered by proton-driven motors. The swimming propulsion is supplied mainly by the thick flagellum. B. japonicum flagellar systems resemble the polar-lateral flagellar systems of Vibrio species but differ in several aspects.
2
Yen, Jiun Y., Katherine M. Broadway, and Birgit E. Scharf. "Minimum Requirements of Flagellation and Motility for Infection of Agrobacterium sp. Strain H13-3 by Flagellotropic Bacteriophage 7-7-1." Applied and Environmental Microbiology 78, no. 20 (August 3, 2012): 7216–22. http://dx.doi.org/10.1128/aem.01082-12.
Full textAbstract:
ABSTRACTThe flagellotropic phage 7-7-1 specifically adsorbs toAgrobacteriumsp. strain H13-3 (formerlyRhizobium lupiniH13-3) flagella for efficient host infection. TheAgrobacteriumsp. H13-3 flagellum is complex and consists of three flagellin proteins: the primary flagellin FlaA, which is essential for motility, and the secondary flagellins FlaB and FlaD, which have minor functions in motility. Using quantitative infectivity assays, we showed that absence of FlaD had no effect on phage infection, while absence of FlaB resulted in a 2.5-fold increase in infectivity. AflaAdeletion strain, which produces straight and severely truncated flagella, experienced a significantly reduced infectivity, similar to that of aflaB flaDstrain, which produces a low number of straight flagella. A strain lacking all three flagellin genes is phage resistant. In addition to flagellation, flagellar rotation is required for infection. A strain that is nonmotile due to an in-frame deletion in the gene encoding the motor component MotA is resistant to phage infection. We also generated two strains with point mutations in themotAgene resulting in replacement of the conserved charged residue Glu98, which is important for modulation of rotary speed. A change to the neutral Gln caused the flagellar motor to rotate at a constant high speed, allowing a 2.2-fold-enhanced infectivity. A change to the positively charged Lys caused a jiggly motility phenotype with very slow flagellar rotation, which significantly reduced the efficiency of infection. In conclusion, flagellar number and length, as well as speed of flagellar rotation, are important determinants for infection by phage 7-7-1.
3
Wu, Cheng-Mu, Hsin-Hui Huang, Li-Hua Li, Yi-Tsung Lin, and Tsuey-Ching Yang. "Molecular Characterization of Three Tandemly Located Flagellin Genes of Stenotrophomonas maltophilia." International Journal of Molecular Sciences 23, no. 7 (March 31, 2022): 3863. http://dx.doi.org/10.3390/ijms23073863.
Full textAbstract:
Stenotrophomonas maltophilia is a motile, opportunistic pathogen. The flagellum, which is involved in swimming, swarming, adhesion, and biofilm formation, is considered a virulence factor for motile pathogens. Three flagellin genes, fliC1, fliC2, and fliC3, were identified from the sequenced S. maltophilia genome. FliC1, fliC2, and fliC3 formed an operon, and their encoding proteins shared 67–82% identity. Members of the fliC1C2C3 operon were deleted individually or in combination to generate single mutants, double mutants, and a triple mutant. The contributions of the three flagellins to swimming, swarming, flagellum morphology, adhesion, and biofilm formation were assessed. The single mutants generally had a compromise in swimming and no significant defects in swarming, adhesion on biotic surfaces, and biofilm formation on abiotic surfaces. The double mutants displayed obvious defects in swimming and adhesion on abiotic and biotic surfaces. The flagellin-null mutant lost swimming ability and was compromised in adhesion and biofilm formation. All tested mutants demonstrated substantial but different flagellar morphologies, supporting that flagellin composition affects filament morphology. Bacterial swimming motility was significantly compromised under an oxidative stress condition, irrespective of flagellin composition. Collectively, the utilization of these three flagellins for filament assembly equips S. maltophilia with flagella adapted to provide better ability in swimming, adhesion, and biofilm formation for its pathogenesis.
4
Campodónico, Victoria L., Nicolás J. Llosa, Martha Grout, Gerd Döring, Tomás Maira-Litrán, and Gerald B. Pier. "Evaluation of Flagella and Flagellin of Pseudomonas aeruginosa as Vaccines." Infection and Immunity 78, no. 2 (December 7, 2009): 746–55. http://dx.doi.org/10.1128/iai.00806-09.
Full textAbstract:
ABSTRACT Pseudomonas aeruginosa is a serious pathogen in hospitalized, immunocompromised, and cystic fibrosis (CF) patients. P. aeruginosa is motile via a single polar flagellum made of polymerized flagellin proteins differentiated into two major serotypes: a and b. Antibodies to flagella delay onset of infection in CF patients, but whether immunity to polymeric flagella and that to monomeric flagellin are comparable has not been addressed, nor has the question of whether such antibodies might negatively impact Toll-like receptor 5 (TLR5) activation, an important component of innate immunity to P. aeruginosa. We compared immunization with flagella and that with flagellin for in vitro effects on motility, opsonic killing, and protective efficacy using a mouse pneumonia model. Antibodies to flagella were superior to antibodies to flagellin at inhibiting motility, promoting opsonic killing, and mediating protection against P. aeruginosa pneumonia in mice. Protection against the flagellar type strains PAK and PA01 was maximal, but it was only marginal against motile clinical isolates from flagellum-immunized CF patients who nonetheless became colonized with P. aeruginosa. Purified flagellin was a more potent activator of TLR5 than were flagella and also elicited higher TLR5-neutralizing antibodies than did immunization with flagella. Antibody to type a but not type b flagella or flagellin inhibited TLR5 activation by whole bacterial cells. Overall, intact flagella appear to be superior for generating immunity to P. aeruginosa, and flagellin monomers might induce antibodies capable of neutralizing innate immunity due to TLR5 activation, but solid immunity to P. aeruginosa based on flagellar antigens may require additional components beyond type a and type b proteins from prototype strains.
5
Li, Chunhao, Melanie Sal, Michael Marko, and Nyles W. Charon. "Differential Regulation of the Multiple Flagellins in Spirochetes." Journal of Bacteriology 192, no. 10 (March 19, 2010): 2596–603. http://dx.doi.org/10.1128/jb.01502-09.
Full textAbstract:
ABSTRACT The expression of flagellin genes in most bacteria is typically regulated by the flagellum-specific sigma28 factor FliA, and an anti-sigma28 factor, FlgM. However, the regulatory hierarchy in several bacteria that have multiple flagellins is more complex. In these bacteria, the flagellin genes are often transcribed by at least two different sigma factors. The flagellar filament in spirochetes consists of one to three FlaB core proteins and at least one FlaA sheath protein. Here, the genetically amenable bacterium Brachyspira hyodysenteriae was used as a model spirochete to investigate the regulation of its four flagellin genes, flaA, flaB1, flaB2, and flaB3. We found that the flaB1 and flaB2 genes are regulated by sigma28, whereas the flaA and flaB3 genes are controlled by sigma70. The analysis of a flagellar motor switch fliG mutant further supported this proposition; in the mutant, the transcription of flaB1 and flaB2 was inhibited, but that of flaA and flaB3 was not. In addition, the continued expression of flaA and flaB3 in the mutant resulted in the formation of incomplete flagellar filaments that were hollow tubes and consisted primarily of FlaA. Finally, our recent studies have shown that each flagellin unit contributes to the stiffness of the periplasmic flagella, and this stiffness directly correlates with motility. The regulatory mechanism identified here should allow spirochetes to change the relative ratio of these flagellin proteins and, concomitantly, vary the stiffness of their flagellar filament.
6
Alexandre, Gladys, René Rohr, and René Bally. "A Phase Variant of Azospirillum lipoferum Lacks a Polar Flagellum and Constitutively Expresses Mechanosensing Lateral Flagella." Applied and Environmental Microbiology 65, no. 10 (October 1, 1999): 4701–4. http://dx.doi.org/10.1128/aem.65.10.4701-4704.1999.
Full textAbstract:
ABSTRACT Flagellation of a nonswimming variant of the mixed flagellated bacterium Azospirillum lipoferum 4B was characterized by electron microscopy, and polyclonal antibodies were raised against polar and lateral flagellins. The variant cells lacked a polar flagellum due to a defect in flagellin synthesis and constitutively expressed lateral flagella. The variant cells were able to respond to conditions that restricted the rotation of lateral flagella by producing more lateral flagella, suggesting that the lateral flagella, as well as the polar flagellum, are mechanosensing.
7
Rabaan, Ali A., Ioannis Gryllos, Juan M. Tomás, and Jonathan G. Shaw. "Motility and the Polar Flagellum Are Required for Aeromonas caviae Adherence to HEp-2 Cells." Infection and Immunity 69, no. 7 (July 1, 2001): 4257–67. http://dx.doi.org/10.1128/iai.69.7.4257-4267.2001.
Full textAbstract:
ABSTRACT Aeromonas caviae is increasingly being recognized as a cause of gastroenteritis, especially among the young. The adherence of aeromonads to human epithelial cells in vitro has been correlated with enteropathogenicity, but the mechanism is far from well understood. Initial investigations demonstrated that adherence of A. caviae to HEp-2 cells was significantly reduced by either pretreating bacterial cells with an antipolar flagellin antibody or by pretreating HEp-2 cells with partially purified flagella. To precisely define the role of the polar flagellum in aeromonad adherence, we isolated the A. caviae polar flagellin locus and identified five polar flagellar genes, in the order flaA, flaB, flaG, flaH, and flaJ. Each gene was inactivated using a kanamycin resistance cartridge that ensures the transcription of downstream genes, and the resulting mutants were tested for motility, flagellin expression, and adherence to HEp-2 cells. N-terminal amino acid sequencing, mutant analysis, and Western blotting demonstrated that A. caviae has a complex flagellum filament composed of two flagellin subunits encoded by flaAand flaB. The predicted molecular mass of both flagellins was ∼31,700 Da; however, their molecular mass estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was ∼35,500 Da. This aberrant migration was thought to be due to their glycosylation, since the proteins were reactive in glycosyl group detection assays. Single mutations in either flaA orflaB did not result in loss of flagella but did result in decreased motility and adherence by approximately 50%. Mutation offlaH, flaJ, or both flagellin genes resulted in the complete loss of motility, flagellin expression, and adherence. However, mutation of flaG did not affect motility but did significantly reduce the level of adherence. Centrifugation of the flagellate mutants (flaA, flaB, and flaG) onto the cell monolayers did not increase adherence, whereas centrifugation of the aflagellate mutants (flaH, flaJ, and flaA flaB) increased adherence slightly. We conclude that maximum adherence of A. caviae to human epithelial cells in vitro requires motility and optimal flagellar function.
8
Fedorov, Oleg V., Michael G. Pyatibratov, Alla S. Kostyukova, Natalja K. Osina, and Valery Yu Tarasov. "Protofilament as a structural element of flagella of haloalkalophilic archaebacteria." Canadian Journal of Microbiology 40, no. 1 (January 1, 1994): 45–53. http://dx.doi.org/10.1139/m94-007.
Full textAbstract:
Flagella of the haloalkalophilic archaebacterium Natronobacterium magadii were purified and characterized. The diameter of the flagella was 10 nm. It was shown that the flagella consist of four major proteins with molecular weights of 105 000, 60 000, 59 000, and 45 000. With decreasing NaCl concentration, the flagella dissociated into protofilaments. The structure of dissociated flagella and individual flagellins was studied by limited proteolysis. It was found that proteolytic cleavage of flagellins in dissociated flagella into high molecular weight fragments (about 40 000) did not lead to protofilament degradation. It was shown that the most stable fragment is formed from the 60 000 molecular weight flagellin. Cleavage of this fragment led to complete disappearance of protofilaments. On the basis of the data obtained, possible principles of archaebacterial flagellar construction are discussed.Key words: flagellin, archaebacteria, protofilaments, Natronobacterium magadii.
9
Rementeria, A., A. B. Vivanco, A. Ramirez, F. L. Hernando, J. Bikandi, S. Herrera-León, A. Echeita, and J. Garaizar. "Characterization of a Monoclonal Antibody Directed against Salmonella enterica Serovar Typhimurium and Serovar [4,5,12:i:−]." Applied and Environmental Microbiology 75, no. 5 (January 5, 2009): 1345–54. http://dx.doi.org/10.1128/aem.01597-08.
Full textAbstract:
ABSTRACT Flagellar extracts of Salmonella enterica serovars expressing phase 2 H1 antigenic complex (H:1,2, H:1,5, H:1,6, and H:1,7) and a mutant flagellin obtained by site-directed mutagenesis of the fljB gene from serovar Typhimurium at codon 218, transforming threonine to alanine, expressed in Escherichia coli (fljB218 A ) were used to analyze the H1 antigenic complex. Cross-reactions were detected by Western blotting and dot blotting using commercial polyclonal antibodies against the different wild-type extracts and mutant FljB218A. Therefore, we produced a monoclonal antibody (MAb), 23D4, isotyped as immunoglobulin M, against H:1,2 S. enterica serovar Typhimurium flagellin. The mutant flagellin was not recognized by this MAb. When a large number of phase 1 and phase 2 flagellin antigens of different serovars were used to characterize the 23D4 MAb, only extracts of serovars Typhimurium and [4,5,12:i:−] reacted. The protein composition of phase 1 and phase 2 extracts and highly purified H:1,2 flagellin from serovar Typhimurium strain LT2 and extract of strain 286 (serovar [4,5,12:i:−]), which reacted with the MAb, was studied. Phase 2 flagellin (FljBH:1,2) was detected in phase 1 and phase 2 flagellar heat extracts of serovar Typhimurium and was the single protein identified in all spots of purified H:1,2 flagellin. FliC, FlgK, and other proteins were detected in some immunoreactive spots and in the flagellar extract of serovar [4,5,12:i:−]. Immunoelectron microscopy of complete bacteria with 23D4 showed MAb attachment at the base of flagella, although the MAb failed to recognize the filament of flagella. Nevertheless, the results obtained by the other immunological tests (enzyme-linked immunosorbent assay, Western blotting, and dot blotting) indicate a reaction against flagellins. The epitopes could also be shared by other proteins on spots where FljB is not present, such as aminopeptidase B, isocitrate lyase, InvE, EF-TuA, enolase, DnaK, and others. In conclusion, MAb 23D4 can be useful for detection and diagnostic purposes of S. enterica serovar Typhimurium and serovar [4,5,12:i:−] and could be also helpful for epitope characterization of flagellum-associated antigens.
10
Mangan, Erin K., Jaleh Malakooti, Anthony Caballero, Paul Anderson, Bert Ely, and James W. Gober. "FlbT Couples Flagellum Assembly to Gene Expression in Caulobacter crescentus." Journal of Bacteriology 181, no. 19 (October 1, 1999): 6160–70. http://dx.doi.org/10.1128/jb.181.19.6160-6170.1999.
Full textAbstract:
ABSTRACT The biogenesis of the polar flagellum of Caulobacter crescentus is regulated by the cell cycle as well as by atrans-acting regulatory hierarchy that functions to couple flagellum assembly to gene expression. The assembly of early flagellar structures (MS ring, switch, and flagellum-specific secretory system) is required for the transcription of class III genes, which encode the remainder of the basal body and the external hook structure. Similarly, the assembly of class III gene-encoded structures is required for the expression of the class IV flagellins, which are incorporated into the flagellar filament. Here, we demonstrate that mutations inflbT, a flagellar gene of unknown function, can restore flagellin protein synthesis and the expression offljK::lacZ (25-kDa flagellin) protein fusions in class III flagellar mutants. These results suggest that FlbT functions to negatively regulate flagellin expression in the absence of flagellum assembly. Deletion analysis shows that sequences within the 5′ untranslated region of the fljK transcript are sufficient for FlbT regulation. To determine the mechanism of FlbT-mediated regulation, we assayed the stability of fljKmRNA. The half-life (t 1/2) of fljKmRNA in wild-type cells was approximately 11 min and was reduced to less than 1.5 min in a flgE (hook) mutant. A flgE flbT double mutant exhibited an mRNA t 1/2of greater than 30 min. This suggests that the primary effect of FlbT regulation is an increased turnover of flagellin mRNA. The increasedt 1/2 of fljK mRNA in aflbT mutant has consequences for the temporal expression offljK. In contrast to the case for wild-type cells,fljK::lacZ protein fusions in the mutant are expressed almost continuously throughout the C. crescentus cell cycle, suggesting that coupling of flagellin gene expression to assembly has a critical influence on regulating cell cycle expression.
Dissertations / Theses on the topic "Flagellen"
1
Lehnen, Daniela. "LrhA als Regulator der Flagellen, Motilität, Chemotaxis und Typ-1-Fimbrien in Escherichia coli." [S.l.] : [s.n.], 2002. http://ArchiMeD.uni-mainz.de/pub/2002/0162/diss.pdf.
Full text
2
Ravaux, Benjamin. "Influence du battement du flagelle et de la composition lipidique du spermatozoïde sur l'étape de fusion des gamètes chez le mammifère." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066597/document.
Full textAbstract:
La fécondation est la rencontre de deux gamètes. Bien que centrale chez les espèces sexuées, les mécanismes membranaires et moléculaires ne sont pas encore établis. La communauté scientifique bute toujours sur la question centrale : Comment le spermatozoïde fusionne-t-il avec l’ovule ? Si des études ont identifié trois protéines essentielles : Izumo1, Juno et CD9, elles montrent aussi que ces acteurs ne sont pas suffisants. Notre étude a eu pour but d’identifier d’autres paramètres potentiels impliqués dans cette machinerie de fusion. Nous nous sommes donc focalisés sur la contribution des lipides spermatiques et sur celle du battement du flagelle. Nous avons développé deux méthodes expérimentales originales. Avec la première, qualifiée de « Bottom-up », nous avons tenté de déterminer la machinerie spermatique minimale pour induire la fusion avec l’ovocyte. L’idée a été de reconstituer pas à pas la membrane de la tête du spermatozoïde, d’abord avec les lipides identifiés lors d’analyses, puis en y incorporant Izumo1. Pour la seconde approche, appelée « Top-down », nous avons développé un outil microfluidique pour guider le spermatozoïde jusqu’à l’ovocyte afin de suivre la rencontre avec le « meilleur » point de vue, dans des conditions in-vitro aussi physiologiques que possible. Nous avons découvert que contrairement à ce que nous pensions, le battement du flagelle ne sert pas uniquement à atteindre l'ovocyte, mais aussi à déclencher la fécondation. En effet, les contraintes mécaniques induisent une réorganisation de la membrane ovocytaire incluant la protéine CD9. Ainsi, la chronologie des événements a pu être obtenue avec une résolution temporelle inégaléeFertilization is the encounter of two gametes. Although this process is crucial for sexual organisms, the timeline of the molecular events is not yet established. The researchers cannot explain: how the spermatozoon fuses with the oocyte? One of the reasons is the lack of experimental methods available. Indeed, the gametes need a specific environment to fertilize. Nevertheless, the scientific community identified three essential proteins: Izumo1 on the spermatozoon, Juno (its receptor) and CD9 on the oocyte membrane. For our part, we tried to determine if the none-proteins environment of Izumo1 and CD9 could influence the gametic interaction. To do so, we were focused on the role of the lipids composition of the sperm membranes and on the influence of the forces developed by the flagellum beating on the oocyte. We designed two original experimental methods to offer a better understanding of the mechanisms inside the gamete contact area. With the first one, we tried to identify the minimal machinery to induce fusion. We started to reconstitute step by step the membrane of the spermatozoon head. We tested first the identified lipids alone, and then we coupled these molecules with Izumo1. With the second one, we developed a microfluidic tool to observe the gametic encounter with the “best” viewpoint in the most physiological in-vitro conditions. We observed that the flagellum beating is not only involved in the crossing of the female genital tract but also in the initiation of the fusion step. Indeed, the mechanical constraints induce membrane reorganization with CD9 recruitment. So we succeed to establish the kinetic of the events with an unequaled resolution
3
Pfiffer, Vanessa. "Molekularbiologische Analyse der Diguanylatzyklase DgcE sowie weiterer biofilmrelevanter Proteine und Signale in Escherichia coli." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/20107.
Full textAbstract:
Für die E. coli K12 Biofilmbildung ist die Expression des Masterregulators CsgD essentiell. Dies erfordert das Signalmolekül c-di-GMP, dessen Auf- und Abbau durch 12 Diguanylatzyklasen (DGCs mit GGDEF-Domänen) und 13 Phosphodiesterasen (PDEs mit EAL-Domänen) erfolgt. DgcE ist mit einer MASE1-umfassenden Transmembranregion (TM), drei PAS-, einer GGDEF- und einer degenerierten EAL-Domäne die strukturell komplexeste DGC und notwendig für die Biofilmbildung. Diese Arbeit zeigt, dass die Aktivität von DgcE einer hoch komplexen Regulation unterliegt. Einzelnen DgcE-Domänen konnten aktivierende bzw. inhibierende Rollen hinsichtlich der Biofilmmatrixsynthese zugeordnet werden. Die Biofilmbildung hängt von DgcE-produziertem c-di-GMP ab, wobei die DgcE-Dimerisierung v.a. durch die PAS-Region vermittelt wird. Die EAL-Domäne wirkt einer aktiven DgcE-Form entgegen. Für die DgcE-vermittelte Matrixproduktion sind die GTPase YjdA und sein Partnerprotein YjcZ nötig. Über Interaktionen mit YjcZ und der TM von DgcE vermittelt YjdA eine Komplexbildung. Die Interaktion von YjdA und DgcE sowie die Matrixproduktion hängen von der GTPase-Aktivität von YjdA ab. GTP wird daher als intrazelluläres Signal vorgeschlagen, das die Aktivierung von DgcE durch YjdA/YjcZ reguliert. Die MASE1-umfassende TM agiert als Zentrale der Signalintegration. Einerseits ist sie nötig für die DgcE-Aktivität und andererseits ist sie an einem massiven Abbau von DgcE beteiligt.
Zudem wurden neu identifizierte Curli-regulierende Gene (rbsK, rbsR, ydcI, yieP, puuR) untersucht, wobei keines über das PdeR/DgcM/MlrA-Modul in die c-di-GMP-vermittelte CsgD-Expression eingreift.
Flagellare Verknotungen in der unteren Schicht von E. coli Makrokolonien tragen zur Morphogenese dieser Makrokolonien bei. Diese Arbeit zeigt, dass Flagellenverknotungen zu einer verminderten Expression der Master-PDE PdeH beitragen, wodurch vermutlich die zelluläre c-di-GMP-Konzentration steigt und somit die Biofilmbildung begünstigt wird.Biofilm formation of E. coli K12 requires the expression of the biofilm master regulator CsgD. This process depends on the signaling molecule c-di-GMP, which is synthesized by 12 diguanylate cyclases (DGCs with GGDEF domains) and degraded by 13 phosphodiesterases (PDEs with EAL domains). DgcE is the most complex DGC with a MASE1-containing transmembrane region (TM), three PAS, a GGDEF and a degenerate EAL domain, and it is essential for biofilm formation. This work shows that the regulation of the DgcE activity is highly complex. It was possible to assign activating and inhibitory roles to single domains of DgcE with regard to the expression of biofilm matrix components. C-di-GMP produced by DgcE is necessary for biofilm matrix production. The dimerization of DgcE is mainly mediated by the PAS region, whereas the EAL domain counteracts an active form of DgcE. DgcE-mediated matrix synthesis requires the activating signal input of the GTPase YjdA and its partner protein YjcZ. DgcE, YjdA and YjcZ form a protein complex in which YjdA directly interacts with YjcZ and the TM of DgcE. The interaction between DgcE and YjdA as well as the matrix expression depend on the GTPase activity of YjdA. Thus, it is proposed that GTP serves as an intracellular signal regulating the activation of DgcE by YjdA/YjcZ. The MASE1-containing TM proved to be a central hub for signal integration. It is both required for DgcE activity and for a massive degradation of DgcE. Furthermore, newly discovered curli-regulating genes (rbsK, rbsR, ydcI, yieP, puuR) have been analyzed. None of those gene products act on CsgD expression via the PdeR/DgcM/MlrA module. Flagellar entangling within the bottom layer of E. coli macrocolonies determines morphogenesis of macrocolonies. The data presented here suggest that the master PDE PdeH is somehow down-regulated by flagellar entangling, which probably results in a higher cellular c-di-GMP concentration, thereby promoting biofilm formation.
4
Florimond, Celia. "Etude et caractérisation de nouvelles protéines du cytosquelette du pathogène Trypanosoma Brucei." Thesis, Bordeaux 2, 2012. http://www.theses.fr/2012BOR21971/document.
Full textAbstract:
La maladie du sommeil ou trypanosomiase africaine humaine fait partie des maladies tropicales négligées sévissant en Afrique sub-saharienne. Elle est causée par le parasite mono-flagellé, Trypanosoma brucei, véhiculé par la mouche tsé-tsé (Glossina spp.). Le flagelle de ce parasite prend naissance au niveau du corps basal et émerge de la cellule en traversant une structure appelée poche flagellaire (FP). Cette poche est formée par l’invagination de la membrane plasmique autour de la base proximale du flagelle. Elle est essentielle à la survie du parasite, car elle constitue l’unique site d’endo- et d’exocytose de la cellule. Cette structure est maintenue autour du flagelle via un constituant du cytosquelette appelé, collier de la poche flagellaire (FPC). Ce collier décrit une structure en anneau ou en fer-à-cheval à la zone de sortie du flagelle. Le premier composant identifié au niveau du FPC est une protéine appelée BILBO1. BILBO1 est essentielle et nécessaire à la biogenèse du FPC et de la FP. Une analyse protéomique et un crible en double-hybride réalisé contre une banque génomique de T. brucei ont permis d’identifier plusieurs partenaires potentiels de BILBO1. Nous avons pu identifier et caractériser de nouvelles protéines du FPC, localisées comme BILBO1 dans une structure en anneau. Nous avons étudié leur fonction chez le parasite, en caractérisant les effets de la surexpression de ces protéines ou de leur ARN interférence sur la croissance et la morphologie cellulaireThe Human African Trypanosomiasis is a Sub-Saharan Neglected Tropical Disease, caused by Trypanosoma brucei, a mono-flagellate protozoan transmitted by the tsetse fly (Glossina spp.). The T. brucei flagellum originates from a cytoplasmic basal body then grows, to emerge from the cell, by traversing an unusual and essential structure called the Flagellar Pocket (FP). This pocket is an invagination of the pellicular membrane at the base of the flagellum. The FP is essential for the survival of the parasite, because it is the unique site for endo- and exocytosis. The Flagellar Pocket Collar (FPC) is a cytoskeletal component of the FP, and is located at the neck of the FP where it maintains a ring/horseshoe structure at the exit site of the flagellum. The FPC contains numerous uncharacterised proteins, including the first protein identified as FPC component - BILBO1. BILBO1 is essential and required for FPC and FP biogenesis. A proteomic analysis and a private two-hybrid genomic screen experiment on T. brucei have revealed a number of potential BILBO1 partners. We found several proteins localize to the FPC like BILBO1 in a ring-like structure. We characterise these new FPC proteins and their function in the parasite. We have characterised the effects of the GFP fusion protein over-expression and RNAi on cell growth and morphology in T. brucei
5
Klindt, Gary. "Hydrodynamics of flagellar swimming and synchronization." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-231897.
Full textAbstract:
What is flagellar swimming? Cilia and flagella are whip-like cell appendages that can exhibit regular bending waves. This active process emerges from the non-equilibrium dynamics of molecular motors distributed along the length of cilia and flagella. Eukaryotic cells can possess many cilia and flagella that beat in a coordinated fashion, thus transporting fluids, as in mammalian airways or the ventricular system inside the brain. Many unicellular organisms posses just one or two flagella, rendering them microswimmers that are propelled through fluids by the flagellar beat including sperm cells and the biflagellate green alga Chlamydomonas.
Objectives. In this thesis in theoretical biological physics, we seek to understand the nonlinear dynamics of flagellar swimming and synchronization. We investigate the flow fields induced by beating flagella and how in turn external hydrodynamic flows change speed and shape of the flagellar beat. This flagellar load-response is a prerequisite for flagellar synchronization. We want to find the physical principals underlying stable synchronization of the two flagella of Chlamydomonas cells.
Results. First, we employed realistic hydrodynamic simulations of flagellar swimming based on experimentally measured beat patterns. For this, we developed analysis tools to extract flagellar shapes from high-speed videoscopy data. Flow-signatures of flagellated swimmers are analysed and their effect on a neighboring swimmer is compared to the effect of active noise of the flagellar beat. We were able to estimate a chemomechanical energy efficiency of the flagellar beat and determine its waveform compliance by comparing findings from experiments, in which a clamped Chlamydomonas is exposed to external flow, to predictions from an effective theory that we designed. These mechanical properties have interesting consequences for the synchronization dynamics of Chlamydomonas, which are revealed by computer simulations. We propose that direct elastic coupling between the two flagella of Chlamydomonas, as suggested by recent experiments, in combination with waveform compliance is crucial to facilitate in-phase synchronization of the two flagella of Chlamydomonas.
6
Chalmeau, Jérôme. "Contribution from nanotechnologies to the study and assembly of the flagellar nano-motor of bacteria." Toulouse, INSA, 2009. http://eprint.insa-toulouse.fr/archive/00000343/.
Full textAbstract:
Le nano-moteur qui se trouve à la base des flagelles des bactéries est une merveille de part sa structure et son rôle dans la survie des bactéries. Il permet la mise en rotation rapide (300Hz) d’un long filament à l’extérieur de la bactérie, filament qui va jouer un rôle comparable à une hélice de sous marin. Malgré sa taille, 45 nm dans son plus grand diamètre, cette nano-bio-machine est composée de milliers de protéines, briques essentielles à la vie. Ces protéines travaillent de concert afin de faire tourner le flagelle bactérien et permettre à la bactérie de se mouvoir dans son environnement au gré du milieu dans lequel elle évolue. Malgré son importance dans la vie bactérienne, son fonctionnement précis reste encore relativement flou aujourd’hui. Sa découverte il y a plus de 30 ans a permis l’accumulation de données qui permettent d’esquisser la structure de certaines des protéines, leur emplacement ou le rôle joue par certaines parties de ces mêmes protéines. D’autres expériences ont permis de déduire des caractéristiques mécaniques, comme les relations couple/vitesse de ce moteur. Cependant, sa description à l’échelle nanométrique reste a ce jour limité et sujette à questions. Dans le cadre de ma thèse, deux approches parallèles et complémentaires ont été développé afin de répondre à ce défi : le réassemblage de manière contrôlé in vitro d’une partie du moteur crucial pour le fonctionnement du moteur, l’étude à grande échelle des interactions entre les protéines identifiées comme étant essentielles à la rotation du flagelle. De nombreux outils qui n’avaient jamais été utilisés pour l’étude du moteur ont été mis en oeuvre : le microscope à force atomique, afin de visualiser dans un environnement proche du milieu natif les parties du moteur réassemblées, et la Micro Balance à Quartz pour les études d’interactions. Des nouvelles données ont pu être obtenues et synthétisées afin de proposer une nouvelle hypothèse de fonctionnement du Nano-moteur flagellaire des bactériesThe bacteria flagellar nanomotor is a nature marvel due to its structure and importance for bacteria. It allows the rotation at high frequency ( 300 Hz) of a long external filament. This filament plays a role comparable to a submarine helix and propels its host in the liquid environment. Despite its size, 45 nm at the largest diameter, this nano-bio-machine is composed of thousands of proteins. These proteins work together in order to generate the flagellar rotation and allow bacteria to swim freely in a liquid environment. Despite its importance for bacteria’s life, its precise mechanism remains unclear today. This motor was discovered more than 3o years ago and a large number of experimental data and hypotheses about its structure and mechanism have been accumulated. The overall assembly, the crystal structure of some constitutive proteins, and the role played by each component permit to draw a possible architecture of the motor. Others experiments has also highlighted some crucial aspects of this machine, through mechanical measurement of the torque developed by the motor, in order to define the torque/speed relationship. However, the nanoscale description of the motor remains limited and many interpretations are still questionable. In this work, I have developed two ambitious parallel and complementary ways to elucidate some open questions: the in vitro re-assembly in a control maner of an essential part of the motor, and a large scale study of the interactions between identified motor’s proteins crucial for the motor rotation. These approaches have been supported by the use of new tools, which had never been used before for studying this nano-motor: the Atomic Force Microscope (AFM), for visualizing in a close native environment part of the motor reassembled, and the Quartz Micro Balance for the interactions study. New experimental datas have been obtained and permitted to propose a new hypothesis of the mechanism of the Bacteria Flagellar Nano-Motor
7
Woudstra, Cedric. "Clostridium botulinum, du génotypage de la toxine en passant par les flagellines jusqu'au séquençage de génomes : un aperçu de la diversité génétique des Clostridies associés au botulisme animal et humain." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1020/document.
Full textAbstract:
Le botulisme est une maladie nerveuse, commune à l’homme et aux animaux, due à l’action de la toxine botulique produite par Clostridium botulinum. Il existe 8 types de toxines dénommées A à H. Les bactéries capables de produire cette toxine se différencient en six groupe sur la base de leurs caractéristiques phénotypiques et biologiques. Les souches de C. botulinum responsables du botulisme humain appartiennent aux groupes I et II selon qu’elles soient protéolytiques ou non. Elles produisent les toxines A, B, E et F, ainsi que le nouveau type H récemment découvert. C. butyricum et C. baratii sont également capables de produire les toxines botuliques de type F et E et appartiennent au groupe V et VI. C. argentinense appartient au groupe IV et est capable de synthétiser la toxine de type G. Elle a été soupçonnée d’être impliquée dans des cas de botulisme infantile en Argentine. Les souches de C. botulinum responsables du botulisme animal appartiennent au groupe III (C. novyi sensu lato) et produisent les toxines C, D et leurs formes mosaïques C/D et D/C. La toxine botulique est le poison le plus puissant connu à ce jour. La dose létale nécessaire pour tuer une personne en bonne santé par intoxication alimentaire est de 70 µg seulement. C’est pourquoi cette toxine a fait l’objet d’études particulièrement approfondies, notamment celles impliquées dans des cas de botulisme humain. Elle peut également être utilisée pour le traitement de certaine pathologie ou la chirurgie esthétique (Botox). Malheureusement, elle peut également être utilisée à mauvais escient, en tant qu’arme de guerre ou à des fins de bioterrorisme. C’est pourquoi l’emploi de la toxine botulique ou de sa bactérie productrice fait l’objet d’une législation particulièrement stricte. Mon projet de doctorat s’est organisé autour de plusieurs projets de recherche visant à développer des méthodes de détection et de typage de du germe et de sa toxine (projets Européens BIOTRACER et AniBioThreat ; projets NRBC-bio ; LNR botulisme aviaire en France). Lors de mes recherches j’ai concentré mon travail sur le développement de méthodes capable de suivre et remonter à la source d’une contamination, qu’elle soit délibérée, accidentelle ou naturelle. Afin d’y parvenir j’ai investigué les gènes des flagellines de C. botulinum groupe I à III, responsables du botulisme humain et animal. L’analyse des gènes flaA et flaB a mis en évidence 5 groupes majeurs et 15 sous-groupes, certain étant spécifiques de régions géographiques. FlaB s’est montré spécifique de C. botulinum type E. Les gènes flagellines fliC, spécifiques à C. botulinum du groupe III, se divisent 5 groupes, avec fliC-I et fliC-IV associés aux types mosaïques C/D et D/C. J’ai étudié la prévalence des souches productrices de toxine de type mosaïques chez les volailles et les bovins. Les résultats montrent que les types C/D et D/C sont majoritaires en Europe. Enfin, j’ai séquencé 17 génomes provenant de souches responsables de botulisme animal en France (14 types C/D et 3 types D/C). Leur analyse montre que ces souches sont très proche génétiquement, entre elles et avec les souches Européennes. Grâce à ces données j’ai mis en évidence un large contenu extra chromosomique dans les souches C/D, qui peut être utilisé pour créer une carte d’identité génétique. D’autre part, l’étude des séquences Crisps à des fins de typage ne s’est pas avérée suffisamment résolutive, du fait de système Crispr-Cas déficient chez les souches C/D. Enfin, un très haut degré de discrimination a été atteint par typage SNP, qui a permis de distinguer jusqu’à l’origine de chaque souche. L’ensemble de ces résultats est développé dans le présent manuscritClostridium botulinum is the etiologic agent of botulism, a deadly paralytic disease that can affects both human and animals. Different bacteria, producing neurotoxins type A to H, are responsible for the disease. They are separated into different groups (I to VI) on the basis of their phenotypical and biological characteristics. Human botulism is mainly due to Groups I and II producing neurotoxins A, B, E and F, with type H recently discovered. Also C. butyricum and C. baratii species (Groups V and VI), producing toxins type F and E respectively, are scarcely reported. C. argentinense Group IV, producing toxin type G, which has been suspected to be associated with infant botulism in Argentina. Animal botulism is mainly due to Group III, which is constituted by C. novyi sensu lato species. They produce toxin types C, D and their mosaic variants. Botulinum neurotoxins are the most powerful toxin known to date with as little as 70 µg enough to kill a person by food poisoning. Therefore, it received a great deal of attention. Botulinum neurotoxins have been deeply studied, especially human related toxins compared to animal. The toxins found to be useful for medical or cosmetic (Botox) treatments, but it was also used as a biological warfare agent, and for bioterrorism. Its extreme potency is equal to its dangerousness. Therefore, governments show concerns of its potential misuse as a bioterrorism weapon; research programs are funded to study and raise awareness about both the toxins and the producing organisms. My PhD work was structured by the different projects I was involved in, which were related to C. botulinum detection and typing, like BIOTRACER and AniBioThreat European projects, the French national CBRN program, or the NRL for avian botulism. The main transversal objective I followed lead me to develop new methods to trace back the origin of C. botulinum contamination, in case of a deliberate, accidental or naturally occurring botulism outbreak. I investigated flagellin genes as potential genetic targets for typing C. botulinum Group I-II and III, responsible for human and animal botulism respectively. Flagellin genes flaA and flaB showed the investigated C. botulinum Group I and II strains to cluster into 5 major groups and up to 15 subgroups, some being specific for certain geographical areas, and flaB being specific to C. botulinum type E. Flagellin fliC gene investigated in C. botulinum Group III showed to cluster into five groups, with fliC-I and fliC-IV associated to type C/D and D/C respectively, being not discriminative enough to differentiate highly genetically related strains. I also studied the prevalence of mosaic toxin genes in C. botulinum Group III in animal botulism, mainly in poultry and bovine. The results brought out the mosaic toxin types C/D and D/C to be predominant in the samples investigated throughout Europe. Finally, I explored the full genome sequences of 14 types C/D and 3 types D/C C. botulinum Group III strains, mainly originating from French avian and bovine botulism outbreaks. Analyses of their genome sequences showed them to be closely related to other European strains from Group III. While studying their genetic content, I was able to point out that the extrachromosomal elements of strains type C/D could be used to generate a genetic ID card. Investigation of Crispr typing method showed to be irrelevant for type C/D, due to a deficient Crispr-Cas mechanism, but deserve more investigation for type D/C. The highest level of discrimination was achieved while using SNP core phylogeny, which allowed distinguishing up to the strain level. Here are the results I’m going to develop in this manuscript
8
Andersen-Nissen, Erica. "Toll-like receptor 5 recognition fo bacterial flagellin /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8341.
Full text
9
Ralston, Katherine Sampson. "Parasites in motion novel roles for the flagellum and flagellar motility /." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1835602901&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
Full text
10
Fort, Cécile. "Les voies du transport intraflagellaire." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066404/document.
Full textAbstract:
Les cils sont des organites essentiels chez la plupart des eucaryotes. Ils sont construits par un mécanisme appelé transport intraflagellaire (IFT). Dans cette thèse, nous avons étudié le rôle de l'IFT chez le protiste Trypanosoma brucei. Par une combinaison d'approches en vidéo-microscopie et en microscopie électronique, nous avons révélé que l'IFT est absent ou s'arrête après ciblage par ARNi de gènes requis pour le transport aller et retour. Dans ces conditions, nous avons démontré que l'IFT n'est pas nécessaire au maintien de la longueur du flagelle mature mais contrôle la distribution de plusieurs protéines non structurales. Les trains IFT transportent la tubuline, le constituant majeur de l'axonème. En collaboration avec l'équipe d'Esben Lorentzen, nous avons mis en évidence l'existence d'un module de liaison à la tubuline sur les protéines IFT74/IFT81. Par FIB-SEM, nous avons démontré que les trains IFT sont présents presque exclusivement sur seulement deux (4 et 7) des 9 doublets de microtubules du flagelle. L'utilisation de méthodes d'imagerie super résolutives par SIM, a permis de montrer sur cellules vivantes, l'existence de deux voies spécifiques pour le trafic IFT aller et retour. Cette restriction s'explique par la présence d'une polyglutamylation plus marquée de la tubuline au niveau de ces doublets. L'inhibition des enzymes responsables de la polyglutamylation freine l'accès des protéines IFT aux flagelles et interfère sévèrement avec la construction de l'organite. Ces travaux démontrent donc un rôle essentiel de la polyglutamylation, qui serait lu par les moteurs du transport intraflagellaireCilia and flagella are essential organelles in most eukaryotes including humans. They are built by an active mechanism termed Intraflagellar Transport or IFT. During this thesis, we have investigated the role and functioning of IFT in the protist Trypanosoma brucei. Using a combination of video-microscopy and electron microscopy, we have revealed that IFT is absent or arrested upon RNAi knockdown of genes required for anterograde and retrograde transport, respectively. In these conditions, we have demonstrated that IFT is not required for maintenance of flagellum length but that IFT controls the distribution of several non-structural proteins, to the contrary of the established dogma. IFT trains transport tubulin, the main component of the axoneme. In collaboration with the team of Esben Lorentzen (MPI Munich), we have revealed the existence of a tubulin-binding domain on proteins IFT74/IFT81. Using FIB-SEM, we have demonstrated that IFT trains are present almost exclusively on only two (4 and 7) out of 9 microtubule doublets. The use of super-resolution imaging methods (work performed at the Janelia Research Institute, USA) allowed us to show for the first time in live cells the existence of two specific bidirectional paths for IFT trafficking. This restriction is explained by differential polyglutamylation on these two doublets. The inhibition of the enzymes responsible for polyglutamylation restricts the access of IFT proteins to flagella, resulting in severe impairment of flagellum elongation. This work demonstrates an essential role for polyglutamylation that could act as a “tubulin code” that would be decrypted by the motors of intraflagellar transport
Books on the topic "Flagellen"
1
Mieses, Juan Carlos. Flagellum dei. Santo Domingo, República Dominicana: Taller, 1987.
Find full text
2
Convegno internazionale di studi storici sulla figura di Attila e sulla discesa degli Unni in Italia nel 452 d.C. (1990 Rome, Italy?). Attila flagellum Dei? Roma: "L'Erma" di Bretschneider, 1994.
Find full text
3
Minamino, Tohru, and Keiichi Namba, eds. The Bacterial Flagellum. New York, NY: Springer New York, 2017. http://dx.doi.org/10.1007/978-1-4939-6927-2.
Full text
5
A, Bloodgood Robert, ed. Ciliary and flagellar membranes. New York: Plenum Press, 1990.
Find full text
6
Bloodgood, Robert A., ed. Ciliary and Flagellar Membranes. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4613-0515-6.
Full text
7
Bloodgood, Robert A. Ciliary and Flagellar Membranes. Boston, MA: Springer US, 1990.
Find full textBook chapters on the topic "Flagellen"
1
Held, Andreas, and Manuela Held. "Excavata besitzen abgewandelte Mitochondrien und außergewöhnliche Flagellen." In Diversität 1 b, 5–7. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-55084-7_2.
Full text
2
Minamino, Tohru, and Shin-Ichi Aizawa. "Biogenesis of Flagella: Export of Flagellar Proteins via the Flagellar Machine." In Protein Secretion Pathways in Bacteria, 249–70. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-010-0095-6_13.
Full text
3
Abhyankar, Krutika, and Monisha Kottayi. "Flagellin." In Springer Protocols Handbooks, 35–39. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2601-6_5.
Full text
4
Ichinose, Y., R. Shimizu, F. Taguchi, K. Takeuchi, M. Marutani, T. Mukaihara, Y. Inagaki, K. Toyoda, and T. Shiraishi. "Role of Flagella and Flagellin in Plant — Pseudomonas syringae Interactions." In Pseudomonas syringae and related pathogens, 311–18. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-017-0133-4_33.
Full text
5
Krafsur, E. S., R. D. Moon, R. Albajes, O. Alomar, Elisabetta Chiappini, John Huber, John L. Capinera, et al. "Flagellum." In Encyclopedia of Entomology, 1464. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-6359-6_3823.
Full text
6
Gooch, Jan W. "Flagellum." In Encyclopedic Dictionary of Polymers, 893. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_13762.
Full text
7
Frankel, Gad, Sharon Moshitch, David Zangen, Adam Friedmann, and Linda Doll. "Salmonella Flagellin - Carriers of Heterologous Antigens and Identification of two new Flagellar Genes." In Biology of Salmonella, 391–94. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4615-2854-8_45.
Full text
8
Mehlhorn, Heinz. "Flagella." In Encyclopedia of Parasitology, 1–3. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-642-27769-6_1203-2.
Full text
9
Mehlhorn, Heinz. "Flagella." In Encyclopedia of Parasitology, 1024–25. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-43978-4_1203.
Full text
10
Mehlhorn, Heinz. "Flagellol®." In Encyclopedia of Parasitology, 1027. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-43978-4_5038.
Full textConference papers on the topic "Flagellen"
1
Taheri, Arash, and Meysam Mohammadi-Amin. "Towards a Multi-Flagella Architecture for E.coli Inspired Swimming Microrobot Propulsion." In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192525.
Full textAbstract:
One of the primary goals of medical micro and nano robots is to reach currently inaccessible areas of the human body and carry out a host of complex operations, such as minimally invasive surgery (MIS), highly localized drug delivery, and screening for diseases at their very early stages. One of the innovative approaches to design microrobot propulsion is based on the flagellar motion of bacteria [1]. Certain bacteria, such as Escherichia coli (E.coli) use multiple flagella often concentrated at one end of their bodies to induce locomotion. Each flagellum is formed in a left-handed helix and has a motor at the base that rotates the flagellum in a corkscrew motion. As pointed out by Purcell in his Lecture “Life at low Reynolds numbers” [2], microorganisms experience an environment quite different from our own. In particular, because of their small size (of the order of microns), inertia is, to them, essentially irrelevant. The fact that inertia is irrelevant for micro-organisms makes it difficult for them to move. The propulsive mechanisms based on flow inertia will not work on a mesoscopic scale. To overcome this problem, organisms living in low Reynolds number regimes have developed moving organelles which have a handedness to them. For instance, E. Coli’s flagella rotate with a helical motion, much like a corkscrew. This configuration produces patterns of motion that do not repeat the first half of the cycle in reverse for the second half, allowing the organisms to achieve movement in their environment.
2
Pyatibratov, M. G., A. S. Syutkin, S. N. Beznosov, A. V. Galeva, and S. Yu Shchyogolev. "Bioengineering of archaeal flagella." In 2nd International Scientific Conference "Plants and Microbes: the Future of Biotechnology". PLAMIC2020 Organizing committee, 2020. http://dx.doi.org/10.28983/plamic2020.203.
Full textAbstract:
It was shown that the Haloferax volcanii flagella assembly system can accept alien flagellins and build functional recombinant flagella. The results can be used for targeted flagella modification to create multifunctional nanomaterials.
3
Jeon, Hyejin, Yoon-Cheol Kim, Eun Goh, Dongwook Yim, Songwan Jin, and Jung Yul Yoo. "The Effect of Design Parameters on the Performance of Flagellar Propeller at Low Reynolds Number." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-16019.
Full textAbstract:
To drive a small object which swims in low Reynolds number situation, we need a new type of propeller which is optimized for low Reynolds number usage since the flow at low Reynolds numbers is dominated by viscous force instead of inertia force. Propeller in a shape of bacterial flagellum can be a strong candidate for propeller of small swimming object. In this paper, we visualized velocity field induced by flagellar shaped propeller using stereoscopic particle image velocimetry. We also have experimentally evaluated the effect of pitch and rotational speeds on the performance of flagellar shaped propeller inspired by flagellum of E.coli using macroscopic model. Silicone oil whose viscosity is 100 times larger than water is used as working fluid to make low Reynolds number situation using macroscopic model. Thrust, torque and velocity were measured as a function of pitch and rotational speed, and efficiency was calculated using measured results. We found that the maximum efficiency of flagellar propeller reaches where the pitch angle is about 40°. However, the effect of rotational speed on the efficiency is relatively smaller than that of pitch. And the flow pattern behind the rotating propeller was altered by pitch of the propeller.
4
Okamoto, R. J., J. Ying, B. L. Lewis, E. C. Ranz, J. Y. Shao, S. K. Dutcher, and P. V. Bayly. "Flexural Rigidity of Intact Chlamydomonas Flagella Measured With an Optical Trap." In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53615.
Full textAbstract:
Flagella and cilia are thin, active organelles protruding from cells that are used to propel the cell or move fluid. The flagellated alga Chlamydomonas reinhardtii is a uni-cellular model organism well-suited for the study of flagellar and cilia mechanics.
5
Cheang, U. Kei, Jun Hee Lee, Paul Kim, and Min Jun Kim. "Magnetic Control of Biologically Inspired Robotic Microswimmers." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-19014.
Full textAbstract:
Bacterial flagella have been employed as nanoactuators for biomimetic microswimmers in low Reynolds number fluidic environments. The microswimmer is a dumbbell-like swimmer that utilizes flagellar hydrodynamics to achieve spiral-type swimming. Flagellar filaments from Salmonella typhimurium are harnessed and functionalized in order to serve as couplers for polystyrene (PS) microbeads and magnetic nanoparticles (MNPs) using avidin-biotin chemistry. The MNP have an iron oxide core that will allow us to actuate the microswimmer under a rotating magnetic field. Using a micromanufacturing process, microswimmer of different configurations can be created to mimic mono- and multi-flagellated bacteria. A magnetic control system consists of electromagnetic coils arranged in an approximate Helmholtz configuration was designed, constructed, and characterized. In conjunction with a LabVIEW input interface, a DAQ controller was used as a function generator to generate sinusoidal waveforms to the power supplies. AC current outputs were supplied from the power supplies to the coils in order to generate a rotating magnetic field. A rotating magnetic field will induce rotation in the flagella conjugated MNP which in term will rotate the flagellar filament into a spiral configuration and achieve propulsion, as in polarly-flagellated bacteria. A high-speed camera provided real-time imaging of the microswimmer motion in a static fluidic environment inside a closed PDMS (Polydimethylsiloxane) chamber. The microswimmers exhibited flagellar propulsion in a low Reynolds number fluidic environment under a rotating magnetic field, which demonstrates its potential for biomedical applications.
6
Al-Fandi, Mohamed G., Ajay P. Malshe, Shankar Sundaram, Jerry Jenkins, Steve Tung, and Jin-Woo Kim. "Simulation and Design of E. Coli-Based Rotary Micropump for Use in Microfluidic Systems: Integration of Micro-Nano-Bio." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41450.
Full textAbstract:
This paper presents the results of the computational fluid dynamic (CFD) modeling of viscous fluid flow in a novel cell motor actuated micropump. A cell motor is a bacterial flagellar cell tethered to a surface by a single flagellum, this flagellum acts as a pivot around which the cell body rotates. As a test case for investigation, the micropump consisted of two Escherichia coli cell motors tethered to the bottom of a microchannel with fixed dimensions. The CFD modeling of the micropump was performed using CFD-ACE+ simulation software (CFD Research Corporation). The biological cell motor was modeled as an ellipse with constant rotational speed of 10 Hz clockwise. The results of this model demonstrated the effect of the biological cell motor placement within the microchannel, as well as the rotational phase between the two biological cell motors, on the volumetric flowrate. Pumping action was observed as the cell motor location was moved adjacent to the sidewall of the microchannel. The rates of fluid pumping were of the order of 11 pL/hr when the cell motors were rotating in phase and their placement was close to the sidewall of the microchannel.
7
Hesse, William R., Matthew Federici, David M. Casale, Peter Fink, Basil Milton, and Min Jun Kim. "Biologically Inspired Robotic Microswimmers." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10565.
Full textAbstract:
Drug delivery systems have had a profound impact on several branches of medicine. Engineers and researchers alike have labored to create a controlled drug delivery device capable of regulated dosage release and a specific cell targeting mechanism. The growing field of biomimicry has inspired several of these drug systems, though success has been limited. The flagellated low Reynolds number propulsion system of Salmonella typhimurium has inspired this specific delivery complex. In this system, the helical flagellar filaments of S. typhimurium are isolated from the bacteria’s cell body and are bound to functionalized paramagnetic microspheres. As a magnetic field is applied to this device, the microsphere rotates, inducing rotation of the helical flagella. This motion creates a locomotive force and drives the device in a predestined direction.
8
Koz, Mustafa, and Serhat Yesilyurt. "Simulation-Based Analysis of the Micropropulsion With Rotating Corkscrew Motion of Flagella." In ASME 2009 Fluids Engineering Division Summer Meeting. ASMEDC, 2009. http://dx.doi.org/10.1115/fedsm2009-78526.
Full textAbstract:
Microorganisms such as ecoli bacterium can propel themselves by means of a corkscrew motion in flow regimes where the Reynolds number is much smaller than one and inertial propulsion methods are ineffective. Micropropulsion with the rotating corkscrew motion of flagella can prove useful as a navigation mechanism for microswimming robots in medical applications. In this work, we present the motion of a microswimmer that consists of an ellipsoid of length two-microns and diameter one micron with a flagellum of length two microns and diameter of 40 nanometers. The microswimmer resembles to a typical ecoli bacterium. We present the effect of parameters such as angular velocity and amplitude of the corkscrew motion. In simulations, time-dependent three-dimensional Navier-Stokes equations are solved in deforming mesh using a commercial package COMSOL. Mesh deformation is specified based on the displacement and rotation of the microswimmer that springs from the net force and torque around the center of mass due to the rotation of the corkscrew-like flagellum. The net linear and angular accelerations of the microswimmer are calculated using ordinary-differential equations that represent the equation of motion, and coupled with the Navier-Stokes equations and the mesh deformation. For simplicity, microswimmer is placed in a cylindrical channel of diameter 20 microns and length 60 microns.
9
Araújo, Fabiana F., Ângela M. A. Pinheiro, Kaio M. Farias, Bernadette F. Lóscio, and Diana M. Oliveira. "FlagelLink." In the 2008 ACM symposium. New York, New York, USA: ACM Press, 2008. http://dx.doi.org/10.1145/1363686.1363980.
Full text
10
Pooran, Ryan, Jin-Woo Kim, Steve Tung, Ajay P. Malshe, and Chuen Cheak Lee. "A Cellular Motor Based Micro Pump: Integration of Cellular Motors With Micro Channels." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41545.
Full textAbstract:
To achieve a high degree of functional density and efficiency, some of the micro actuators in MEMS can be replaced by active biological elements. An example of this is the cellular motor micro pump (CMMP) currently under development at the University of Arkansas. The CMMP is realized through the tethering of a harmless strain of Escherichia coli cells to a MEMS-based micro fluidic channel. In a free moving state, an E.coli cell ‘swims’ by rotating its’ flagella, driven at the base by a rotary motor. When a cell is attached to a surface by a single shortened flagellar filament (∼0.5 micron long), the motor turns the entire cell body at a high rotational speed. The CMMP utilizes this mechanism to transport liquid in a micro fluidic channel through viscous pumping. This paper describes two important areas in the CMMP development process: cell tethering in micro channels fabricated from various substrate materials and visualization of tethered cell behavior through fluorescent microscopy.
Reports on the topic "Flagellen"
1
Blaser, Martin J., Janet A. Hopkins, Guillermo I. Perez-Perez, Henry J. Cody, and Diane G. Newell. Antigenicity of Campylobacter Jejuni Flagella. Fort Belvoir, VA: Defense Technical Information Center, March 1986. http://dx.doi.org/10.21236/ada265460.
Full text
2
Montie, Thomas C. Mechanism of Flagellar Vaccine Protection Related to Pseudomonas Pathogenesis in Trauma Burns. Fort Belvoir, VA: Defense Technical Information Center, January 1989. http://dx.doi.org/10.21236/ada203539.
Full text
3
Qiu, D., Q. Tu, Zhili He, and Jizhong Zhou. Comparative Genomics Analysis and Phenotypic Characterization of Shewanella putrefaciens W3-18-1: Anaerobic Respiration, Bacterial Microcompartments, and Lateral Flagella. Office of Scientific and Technical Information (OSTI), May 2010. http://dx.doi.org/10.2172/986497.
Full text
4
Sessa, Guido, and Gregory Martin. role of FLS3 and BSK830 in pattern-triggered immunity in tomato. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7604270.bard.
Full textAbstract:
Pattern-recognition receptors (PRRs) located on the plant cell surface initiate immune responses by perceiving conserved pathogen molecules known as pathogen-associated molecular patterns (PAMPs). PRRs typically function in multiprotein complexes that include transmembrane and cytoplasmickinases and contribute to the initiation and signaling of pattern-triggered immunity (PTI). An important challenge is to identify molecular components of PRR complexes and downstream signaling pathways, and to understand the molecular mechanisms that mediate their function. In research activities supported by BARD-4931, we studied the role of the FLAGELLIN SENSING 3 (FLS3) PRR in the response of tomato leaves to flagellin-derivedPAMPs and PTI. In addition, we investigated molecular properties of the tomato brassinosteroid signaling kinase 830 (BSK830) that physically interacts with FLS3 and is a candidate for acting in the FLS3 signaling pathway. Our investigation refers to the proposal original objectives that were to: 1) Investigate the role of FLS3 and its interacting proteins in PTI; 2) Investigate the role of BSK830 in PTI; 3) Examine molecular and phosphorylation dynamics of the FLS3-BSK830 interaction; 4) Examine the possible interaction of FLS3 and BSK830 with Pstand Xcveffectors. We used CRISPR/Cas9 techniques to develop plants carrying single or combined mutations in the FLS3 gene and in the paralogsFLS2.1 and FLS2.2 genes, which encode the receptor FLAGELLIN SENSING2 (FLS2), and analyzed their function in PTI. Domain swapping analysis of the FLS2 and FLS3 receptors revealed domains of the proteins responsible for PAMP detection and for the different ROS response initiated by flgII-28/FLS3 as compared to flg22/FLS2. In addition, in vitro kinase assays and point mutations analysis identified FLS2 and FLS3 domains required for kinase activity and ATP binding. In research activities on tomato BSK830, we found that it interacts with PRRs and with the co-receptor SERK3A and PAMP treatment affects part of these interactions. CRISPR/Cas9 bsk830 mutant plants displayed enhanced pathogen susceptibility and reduced ROS production upon PAMP treatment. In addition, BSK830 interacted with 8 Xanthomonastype III secreted effectors. Follow up analysis revealed that among these effectors XopAE is part of an operon, is translocated into plant cells, and displays E3 ubiquitinligase activity. Our investigation was also extended to other Arabidopsis and tomato BSK family members. Arabidopsis BSK5 localized to the plant cell periphery, interacted with receptor-like kinases, and it was phosphorylatedin vitro by the PEPR1 and EFRPRRs. bsk5 mutant plants displayed enhanced susceptibility to pathogens and were impaired in several, but not all, PAMP-induced responses. Conversely, BSK5 overexpression conferred enhanced disease resistance and caused stronger PTI responses. Genetic complementation suggested that proper localization, kinase activity, and phosphorylation by PRRs are critical for BSK5 function. BSK7 and BSK8 specifically interacted with the FLS2 PRR, their respective mutant plants were more susceptible to B. cinereaand displayed reduced flg22-induced responses. The tomato BSK Mai1 was found to interact with the M3KMAPKKK, which is involved in activation of cell death associated with effector-triggered immunity. Silencing of Mai1 in N. benthamianaplants compromised cell death induced by a specific class of immune receptors. In addition, co-expression of Mai1 and M3Kin leaves enhanced MAPKphosphorylation and cell death, suggesting that Mai1 acts as a molecular link between pathogen recognition and MAPK signaling. Finally, We identified the PP2C phosphatase Pic1 that acts as a negative regulator of PTI by interacting with and dephosphorylating the receptor-like cytoplasmickinase Pti1, which is a positive regulator of plant immunity. The results of this investigation shed new light on the molecular characteristics and interactions of components of the immune system of crop plants providing new knowledge and tools for development of novel strategies for disease control.
5
Mao, Chuanbin, Penghe Qiu, Lin Wang, Songyuan Yao, Xuewei Qu, and Ningyun Zhou. Controlled synthesis and ordered assembly of Co<sub>3</sub>O<sub>4</sub> nanowires using genetically engineered bacterial flagella as biotemplates (Final Technical Report). Office of Scientific and Technical Information (OSTI), March 2021. http://dx.doi.org/10.2172/1772896.
Full text