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Brandon R Anjuwon-Foster, Rita Tamayo
In the human intestinal pathogen Clostridium difficile, flagella promote adherence to intestinal epithelial cells. Flagellar gene expression also indirectly impacts production of the glucosylating toxins, which are essential to diarrheal disease development. Thus, factors that regulate the expression of the flgB operon will likely impact toxin production in addition to flagellar motility. Here, we report the identification a "flagellar switch" that controls the phase variable production of flagella and glucosylating toxins...
March 27, 2017: PLoS Genetics
Magali Zbinden, Camille Berthod, Nicolas Montagné, Julia Machon, Nelly Léger, Thomas Chertemps, Nicolas Rabet, Bruce Shillito, Juliette Ravaux
The detection of chemical signals is involved in a variety of crustacean behaviors, such as social interactions, search and evaluation of food and navigation in the environment. At hydrothermal vents, endemic shrimp may use the chemical signature of vent fluids to locate active edifices, however little is known on their sensory perception in these remote deep-sea habitats. Here, we present the first comparative description of the sensilla on the antennules and antennae of 4 hydrothermal vent shrimp (Rimicaris exoculata, Mirocaris fortunata, Chorocaris chacei, and Alvinocaris markensis) and of a closely related coastal shrimp (Palaemon elegans)...
February 22, 2017: Chemical Senses
Amy E Baker, George A O'Toole
Many bacteria move through liquids and across surfaces using flagella - filaments propelled by a membrane-embedded rotary motor. Much is known about the flagellum: its basic structure, the function of its individual motor components, and the regulation of its synthesis. However, we are only beginning to identify the dynamics of flagellar proteins and to understand how the motor structurally adapts to environmental stimuli. In this review, we discuss the external and cellular factors that influence the dynamics of stator complexes (the ion-conducting channels of the flagellar motor)...
March 20, 2017: Journal of Bacteriology
Hana Tlapák, Kerstin Rydzewski, Tino Schulz, Dennis Weschka, Eva Schunder, Klaus Heuner
Legionella oakridgensis is causing the Legionnaires' disease but is known to be less virulent than Legionella pneumophilaL. oakridgensis is one of the Legionella species that is non-flagellated. The genes of the flagellar regulon are absent; except the alternative sigma-28 factor (FliA) and its anti-sigma-28 factor (FlgM). Similar to L. oakridgensis, Legionella adelaidensis and Legionella londiniensis, located in the same phylogenetic clade, they have no flagellar regulon, although both are positive for fliA and flgM Herein, we investigated the role and function of both genes to better understand the role of FliA, the positive regulator of flagellin expression, in non-flagellated strains...
March 20, 2017: Journal of Bacteriology
Bo Lv, Lei Wan, Michael Taschner, Xi Cheng, Esben Lorentzen, Kaiyao Huang
Cilia are microtubule based organelles and perform motile, sensing and signaling functions. The assembly and maintenance of cilia depend on intraflagellar transport. Besides ciliary localization, most IFT proteins accumulate at basal bodies. However, little is known about the molecular mechanism of basal body targeting of IFT proteins. We first identified the possible basal body targeting sequence of IFT46 by expressing IFT46 truncations in ift46-1 mutant. The C-terminal sequence 246-321 aa, termed BBTS3, was sufficient to target YFPs to basal bodies in ift46-1 Interestingly, BBTS3 is also responsible for the ciliary targeting of IFT46...
March 16, 2017: Journal of Cell Science
Katsutoshi Mizuno, Roger D Sloboda
Changes in protein activity driven by post translational modifications comprise an important mechanism for the control of many cellular processes. Several flagellar proteins are methylated on arginine residues during flagellar resorption; however, the function is not understood. To learn more about the role of protein methylation during flagellar dynamics, we have focused on protein arginine methyltransferases (PRMTs) 1, 3, 5, and 10. These PRMTs localize to the tip of flagella and in a punctate pattern along the length, very similar, but not identical, to that of intraflagellar transport (IFT) components...
March 15, 2017: Molecular Biology of the Cell
Meng Qi, Xiangjun Gong, Bo Wu, Guangzhao Zhang
Landing of bacteria for adhesion on a surface is a common phenomenon in our life. However, how surface properties are involved in this process remains largely unclear. Using digital holographic microscopy, we investigated the three-dimensional motions of flagellate Escherichia coli swimming near polymeric surfaces with different properties in aqueous solution before adhesion. We monitored the bacteria landing dynamics, which shows that the density distribution, the probability, and the orientation for collisions of the bacteria are determined by their motility but are slightly affected by the surface properties...
March 28, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Julia A Horstmann, Erik Zschieschang, Theresa Truschel, Juana de Diego, Michele Lunelli, Manfred Rohde, Tobias May, Till Strowig, Theresia Stradal, Michael Kolbe, Marc Erhardt
The flagellum is a sophisticated nanomachine and an important virulence factor of many pathogenic bacteria. Flagellar motility enables directed movements towards host cells in a chemotactic process and near surface swimming on cell surfaces is crucial for selection of permissive entry sites. The long external flagellar filament is made of tens of thousands subunits of a single protein, flagellin, and many Salmonella serovars alternate expression of antigenically distinct flagellin proteins, FliC and FljB. However, the role of the different flagellin variants during gut colonization and host cell invasion remains elusive...
March 13, 2017: Cellular Microbiology
Jennifer L Hoeflinger, Michael J Miller
Cronobacter sakazakii is an opportunistic nosocomial and foodborne pathogen that causes severe infections with high morbidity and mortality rates in neonates, the elderly, and immunocompromised individuals. Little is known about the pathogenesis mechanism of this pathogen and if there are any consequences of C. sakazakii colonization in healthy individuals. In this study, we characterized the mechanisms of autoaggregation in C. sakazakii ATCC 29544 (CS29544). Autoaggregation in CS29544 occurred rapidly, within 30 min, and proceeded to a maximum of 70%...
2017: Frontiers in Microbiology
Soumita Dutta, Prachee Avasthi
The unicellular green alga Chlamydomonas reinhardtii is an ideal model organism for studies of ciliary function and assembly. In assays for biological and biochemical effects of various factors on flagellar structure and function, synchronous culture is advantageous for minimizing variability. Here, we have characterized a method in which 100% synchronization is achieved with respect to flagellar length but not with respect to the cell cycle. The method requires inducing flagellar regeneration by amputation of the entire cell population and limiting regeneration time...
March 2017: MSphere
Thomas Schwarz, Barbara Prieler, Johannes A Schmid, Pawel Grzmil, Juergen Neesen
Disruption of murine Hook1 results in a disturbed spermatogenesis and consequently leads to male infertility in mice. Within these mice abnormal sperm development starts with a disorganization of the microtubular manchette in elongating spermatids that leads to an abnormal head shape as well as to distinctive structural changes in the flagella of the sperm. To elucidate Hook1 function in male germ cell differentiation a yeast two-hybrid screen was performed using a murine testicular library, which leads to the identification of several putative Hook1 interacting proteins...
February 20, 2017: European Journal of Cell Biology
Jong Soo Park
The genus Tetramitus is a representative amoeboflagellate group within the Heterolobosea, and currently contains over a dozen species. Here, a new heterolobosean amoeboflagellate was isolated from a freshwater pond on Dokdo Island, Korea. The amoebae have eruptive pseudopodia, no uroidal filament, and a nucleus with a central nucleolus. The length and width of the amoebae are 15.5-28.0 μm and 5.4-12.6 μm, respectively. The flagellates are conical, with 4 flagella of equal length (~10 μm). There is a discrete rostrum in the subapical region of the flagellate form...
March 9, 2017: Journal of Eukaryotic Microbiology
V K Sharma, D O Bayles, D P Alt, T Looft, B W Brunelle, J A Stasko
BACKGROUND: Escherichia coli O157:H7 (O157) strain 86-24, linked to a 1986 disease outbreak, displays curli- and biofilm-negative phenotypes that are correlated with the lack of Congo red (CR) binding and formation of white colonies (CR(-)) on a CR-containing medium. However, on a CR medium this strain produces red isolates (CR(+)) capable of producing curli fimbriae and biofilms. RESULTS: To identify genes controlling differential expression of curli fimbriae and biofilm formation, the RNA-Seq profile of a CR(+) isolate was compared to the CR(-) parental isolate...
March 8, 2017: BMC Microbiology
Nana Kinoshita, Chikako Nagasato, Taizo Motomura
Brown algae exhibit three patterns of sexual reproduction: isogamy, anisogamy, and oogamy. Unicellular swarmers including gametes and zoospores bear two heterogenous flagella, an anterior flagellum with mastigonemes (fine tripartite hairs) and a posterior one. In seawater, these flagellates usually receive physico-chemical signals for finding partners and good habitats. It is well known that brown algal swarmers change their swimming direction depending on blue light (phototaxis), and male gametes do so, based on the sex pheromones from female gametes (chemotaxis)...
March 7, 2017: Journal of Plant Research
Thibaud T Renault, Anthony O Abraham, Tobias Bergmiller, Guillaume Paradis, Simon Rainville, Emmanuelle Charpentier, Călin C Guet, Yuhai Tu, Keiichi Namba, James P Keener, Tohru Minamino, Marc Erhardt
The bacterial flagellum is a self-assembling nanomachine. The external flagellar filament, several times longer than a bacterial cell body, is made of a few tens of thousands subunits of a single protein: flagellin. A fundamental problem concerns the molecular mechanism of how the flagellum grows outside the cell, where no discernible energy source is available. Here, we monitored the dynamic assembly of individual flagella using in situ labelling and real-time immunostaining of elongating flagellar filaments...
March 6, 2017: ELife
Eun A Kim, Joseph Panushka, Trevor Meyer, Ryan Carlisle, Samantha Baker, Nicholas Ide, Michael Lynch, Brian R Crane, David F Blair
Structural models of the complex that regulates the direction of flagellar rotation assume either ~34 or ~25 copies of the protein FliG. Support for ~34 came from cross-linking experiments identifying an inter-subunit contact most consistent with that number; support for ~25 came from the observation that flagella can assemble and rotate when FliG is genetically fused to FliF, for which the accepted number is ~25. Here, we have undertaken cross-linking and other experiments to address more fully the question of FliG number...
March 1, 2017: Journal of Molecular Biology
Hiroaki Ishikawa, Wallace F Marshall
Cilia and flagella are microtubule-based organelles whose assembly requires a motile process, known as intraflagellar transport (IFT), to bring tubulin and other components to the distal tip of the growing structure. The IFT system uses a multiprotein complex with components that appear to be specialized for the transport of different sets of cargo proteins. The mechanisms by which cargo is selected for ciliary import and transport by IFT remain an area of active research. The complex dynamics of cilia and flagella are under constant regulation to ensure proper length control, and this regulation appears to involve regulation at the stage of IFT injection into the flagellum, as well as regulation of flagellar disassembly and, possibly, of cargo binding...
March 1, 2017: Cold Spring Harbor Perspectives in Biology
Bram Bet, Gijs Boosten, Marjolein Dijkstra, René van Roij
We combine a general formulation of microswimmer equations of motion with a numerical bead-shell model to calculate the hydrodynamic interactions with the fluid, from which the swimming speed, power, and efficiency are extracted. From this framework, a generalized Scallop theorem emerges. The applicability to arbitrary shapes allows for the optimization of the efficiency with respect to the swimmer geometry. We apply this scheme to "three-body swimmers" of various shapes and find that the efficiency is characterized by the single-body friction coefficient in the long-arm regime, while in the short-arm regime the minimal approachable distance becomes the determining factor...
February 28, 2017: Journal of Chemical Physics
Karl F Lechtreck, Julie C Van De Weghe, J Aaron Harris, Peiwei Liu
Cilia and eukaryotic flagella are threadlike cell extensions with motile and sensory functions. Their assembly requires intraflagellar transport (IFT), a bidirectional motor-driven transport of protein carriers along the axonemal microtubules. IFT moves ample amounts of structural proteins including tubulin into growing cilia likely explaining its critical role for assembly. IFT continues in non-growing cilia contributing to a variety of processes ranging from axonemal maintenance and the export of non-ciliary proteins to cell locomotion and ciliary signaling...
March 1, 2017: Traffic
Daniel Pletzer, Sarah C Mansour, Kelli Wuerth, Negin Rahanjam, Robert E W Hancock
Only a few, relatively cumbersome animal models enable long-term Gram-negative bacterial infections that mimic human situations, where untreated infections can last for weeks. Here, we describe a simple murine cutaneous abscess model that enables chronic or progressive infections, depending on the subcutaneously injected bacterial strain. In this model, Pseudomonas aeruginosa cystic fibrosis epidemic isolate LESB58 caused localized high-density skin and soft tissue infections and necrotic skin lesions for up to 10 days but did not disseminate in either CD-1 or C57BL/6 mice...
February 28, 2017: MBio
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