Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FLAGELLATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,009 records · Page 56Linked to original sources
PubMed2001

Flagellin expressed by live Salmonella vaccine strains induces distinct antibody responses following delivery via systemic or mucosal immunization routes.

Salmonella flagellin, expressed as flagella in live attenuated vaccine strains, elicits distinct systemic (IgG) and secreted (IgA) antibody responses in mice following delivery via mucosal (nasal/oral) or parenteral (intraperitoneal (i.p.)) immunization routes. Reduced flagellin-specific antibodies were detected either systemically or locally following delivery of flagellated derivatives of aroA Salmonella enterica serovar Dublin SL1438 via the nasal route, the most effective mucosal site for activation of immune responses in mice. In contrast, flagellin represents the most potent Salmonella antigen for the generation of specific serum antibody (IgG) responses following i.p. inoculations. The distinct immunogenic properties of Salmonella flagellin could not be ascribed to deficient colonization, reduced invasive ability or loss of the flagellin expression by the flagellated vaccine strains.

Administration, Intranasal↗
PubMed1999

Ultrastructural characterization of Anaerobiospirillum succiniciproducens and its differentiation from Campylobacter species.

The anaerobic spiral-shaped bacterium Anaerobiospirillum succiniciproducens was isolated from the blood of an AIDS patient for the first time in Europe. Electron-microscopical methods, especially negative staining, allowed rapid morphological classification and differentiation from Campylobacter species. While A. succiniciproducens revealed lophotriche flagellation all the investigated Campylobacter species showed monotriche flagellation. The cell diameter of A. succiniciproducens was at least double that of the investigated Campylobacter species. Other ultrastructural features, such as a ring-like structure underneath the flagellar area and fibrils arranged parallel along the axis, were also specific to A. succiniciproducens.

AIDS-Related Opportunistic Infections↗
PubMed2002

Detection of sialoglycomolecules in five plant trypanosomatids and in an insect phytophagous isolate.

The sialoglycoprotein profiles of five plant trypanosomatids (Phytomonas spp.) and of one flagellate (Herpetomonas sp.) isolated from the salivary gland of a phytophagous insect (Phthia picta) were analyzed by Western blotting using three distinct lectins (LFA, SNA and MAA), which recognize specifically sialic acid residues in glycoconjugates. All six flagellates presented at least one polypeptide recognized by the lectins, with the exception of Phytomonas françai, which did not show any reactivity with SNA agglutinin. Phytomonas serpens and P. françai showed the most distinct pattern of sialoglycoproteins. Phytomonas mcgheei, Herpetomonas sp. and the two other Phytomonas spp., isolated from latex, displayed an identical sialomolecule profile. We discuss the possible role of the sialoglycoproteins in the physiology of these trypanosomatids.

Animals↗
PubMed2005

The white pulp in the setting of the septic spleen caused by different bacteria: a comparative morphometric study.

In the past little attention has been paid to histomorphologic changes accompanying the phenomenon of the septic spleen, thus indirectly reinforcing the old axiom that the spleen is an organ of mystery. It is especially noteworthy that the relationship between different causative bacteria and histopathologic abnormalities of the white pulp has not been investigated. In this study morphometric analysis was performed on the white pulp of 30 spleens obtained at autopsy from individuals with premortal sepsis. A strictly defined age- and sex-matched control group was analyzed for statistical comparison. Our findings demonstrate a significant depletion of B- and T-areas in the septic spleen, accompanied by a significant tendency towards reactive germinal center hyperplasia regardless of the type of bacteria responsible. However, depletion of splenic B-areas was shown to be significantly pronounced in the setting of premortal enterococcemia in comparison with a panel of gram-negative flagellated bacteria. It is felt that certain bacterial virulence factors (e.g. flagellation and/or structural components of the cell wall) might be pathogenetically involved in the observed changes, reflecting a partially different activation of splenic lymphocytes in the setting of the septic spleen.

Aged↗
PubMed1975

Programmed synthesis of flagellar tubulin during cell differentiation in Naegleria.

Amebae of Naegleria gruberi differentiate into flagellates when transferred from growth medium to non-nutrient buffer. This differentiation, which requires 48 min at 28 degrees C, is dependent on transcription and translation. Tubulin of the flagellar outer doublets comprises about 0.15% of the protein of flagellate, and only about 1-2% of the total tubulin. An antiserum to flagellar (outer-doublet) tubulin contains antibodies that react selectively with flagellar tubulin. Measurements using this antiserum have shown that 97-98% of the flagellar tubulin antigen appears during differentiation. The appearance of tubulin antigen is sensitive to actinomycin D and cycloheximide. Isotope dilution experiments using [35S]methione demonstrated that at least 70% of the flagellar tubulin is synthesized from amino acids during differentiation. Experiments using both the specific antiserum and isotopes have shown that flagellar tubulin synthesis begins about one-third of the way through differentiation, before any morphological change has occurred. These experiments demonstrate that most, if not all, of the flagellar tubulin is synthesized de novo during differentiation, and that cells selectively use a specific subpopulation of tubulin in assembling the outer doub)lets. The results bring into focus major unsolved questions about the synthesis and assembly of flagellar tubulin.

Amoeba↗
PubMed1997

Cochlosoma infections in finches.

OBJECTIVE: To survey finches in pet shops for Cochlosoma infection and evaluate the efficacy of antiprotozoal therapy with metronidazole or ronidazole. DESIGN: A survey of pet shop finches and drug efficacy trials. PROCEDURE: Finches in pet shops were randomly selected and their faeces examined microscopically for motile Cochlosoma sp trophozoites. Drug trials were carried out on 60 adult finches with naturally occurring infections. Body weight was measured and the faeces of each bird was examined for trophozoites at the beginning and 7 days after the end of treatment. In some birds, additional daily faecal examinations were done until three consecutive negative results were obtained. Metronidazole was administered at various dose rates by crop gavage or in drinking water to eight groups of five to ten finches each. Ronidazole was given in water for 7 days to ten finches. In addition, six finches whose faeces tested positive were necropsied and their tissues collected for histological examination. RESULTS: Motile flagellates in the faeces were identified as C anatis-like protozoa. Red-headed parrot-finches, Bengalese and Lady Gould finches were found to be most commonly infected. Cochlosoma sp was also found in the blue-faced parrot-finch, zebra finch, painted finch, nutmeg mannikin and double-barred finch. Metronidazole and ronidazole were found to be effective against Cochlosoma sp. Histological findings on infected adult finches were normal, except for the presence of numerous flagellates between the colorectal villi and cloacal mucosal folds. CONCLUSIONS: Cochlosoma anatis-like organisms can infect several species of finches and in adult finches are confined to the colorectum and cloaca. Infection in adult finches was mostly subclinical and could be treated effectively with metronidazole or ronidazole.

Animals↗
PubMed1968

Trypanosome transmitted by Phlebotomus: first report from the Americas.

Transmission studies carried out in the laboratory incriminated Phlebotomus vexator occidentis as a vector of a species of trypanosome that infects Bufo boreas halophilus. Toads free of parasites contracted the trypanosome after eating infected flies and after intraperitoneal inoculation of flagellates cultured from the hindgut of flies that had fed on infected toads. Discovery of this vectorhost-parasite system in the Americas, and the localization of promastigote flagellates (leptomonads) in the hindgut of the vector, should assist in clarifying interpretative problems associated with infection of wild-caught flies in studies on leishmaniasis in the Americas and elsewhere.

Animals↗
PubMed1971

Bacterial differentiation.

The foregoing studies are intended to define a differentiation process and to permit genetic access to the mechanisms that control this process. In order to elucidate the basic mechanisms whereby a cell dictates its own defined morphogenic changes, we have found it helpful to study an organism that can be manipulated both biochemically and genetically. We have attempted to develop the studies initiated by Poindexter,Stove and Stanier, and Schmidt and Stanier (16, 17, 20) with the Caulobacter genus so that these bacteria can serve as a model system for prokaryotic differentiation. The Caulobacter life cycle, defined in synchronously growing cultures, includes a sequential series of morphological changes that occur at specific times in the cycle and at specific locations in the cell. Six distinct cellular characteristics, which are peculiar to these bacteria, have been defined and include (i) the synthesis of a polar organelle which may be membranous (21-23), (ii) a satellite DNA in the stalked cell (26), (iii) pili to which RNA bacteriophage specifically adsorb (16, 33), (iv) a single polar flagellum(17), (v) a lipopolysaccharide phage receptor site (27), and (vi) new cell wall material at the flagellated pole of the cell giving rise to a stalk (19, 20). Cell division, essential for the viability of the organism, is dependent on the irreversible differentiation of a flagellated swarmer cell to a mature stalked cell. The specific features of the Caulobacter system which make it a system of choice for studies of the control of sequential events resulting in cellular differentiation can be summarized as follows. 1) Cell populations can be synchronized, and homogeneous populations at each stage in the differentiation cycle can thus be obtained. 2) A specific technique has been developed whereby the progress of the differentiation cycle can be accurately measured by adsorption of labeled RNA phage or penetration of labeled phage DNA into specific cell forms. This technique can be used to select for mutants blocked in the various stages of morphogenesis. 3) Temperature-sensitive mutants of Caulobacter that are restricted in macromolecular synthesis and development at elevated temperatures have been isolated. 4) Genetic exchange in the Calflobacter genus has been demonstrated and is now being defined. Two questions related to control processes can now readily be approached experimentally. (i) Is the temporal progression of events occurring during bacterial differentiation controlled by regulator gene products? (ii) Is the differentiation cycle like a biosynthetic pathway where one event must follow another? The availability of temperature-sensitive mutants blocked at various stages of development permits access to both questions. An interesting feature of the differentiation cycle is that the polar organelle may represent a special segregated unit which is operative in the control of the differentiation process. Perhaps the sequential morphogenic changes exhibited by Caulobacter are dependent on the initial synthesis of this organelle. Because the ultimate expression of cell changes are dependent on selective protein synthesis, specific messenger RNA production-either from DNA present in an organelle or from the chromosome-may prove to be a controlling factor in cell differentiation. We have begun studies with RNA polymerase purified from Caulobacter crescentus to determine whether cell factors or alterations in the enzyme structure serve to change the specificity of transcription during the cell cycle. Control of sequential cell changes at the level of transcription has long been postulated and has recently been substantiated in the case of Bacillus sporulation (6). The Caulobacter bacteria now present another system in which direct analysis of these control mechanisms is feasible.

Adenine↗
PubMed1991

Role of flagella in adhesion of Pseudomonas fluorescens to tendon slices.

Tendon slices were used as model surfaces to investigate the role of flagella in the adhesion of Pseudomonas fluorescens to meat. The slices were introduced into a specially designed flow chamber, which was then filled with a suspension of the organism, and the tendon surface was observed at a x640 magnification. The same events that occur during the colonization of glass surfaces (apical adhesion of cells with rotation around the contact point, longitudinal adhesion, detachment of apically and longitudinally adherent cells) were also observed on tendon. Mechanical removal of the flagella resulted in no change in the contact angles with 0.1 M saline or alpha-bromonaphthalene, in the electrophoretic mobility, or in the adhesion of the organism to hydrophobic and ion-exchange resins. In addition, cells from which flagella had been mechanically removed still adhered extensively to tendon. Nevertheless, under comparable conditions (bacterial concentration, contact time), flagellated cells adhered to tendon in larger numbers than did deflagellated cells. This was entirely due to the ability of the motile flagellated cells to reach tendon in greater numbers than deflagellated cells.

Animals↗
PubMed1995

Regeneration of phosphorus and nitrogen by four species of heterotrophic nanoflagellates feeding on three nutritional States of a single bacterial strain.

Three physiological states of a single bacterial strain, namely, balanced, phosphorus-rich, and nitrogen-rich bacteria, were obtained by culturing a bacterial strain in chemostats under three different nutrient regimens. Each was shown to be distinctly different in elemental composition with respect to C/N/P ratio. These bacteria were fed to four species of heterotrophic nanoflagellates in batch culture grazing experiments, and the percent regeneration efficiencies of bacterium-bound nitrogen and phosphorus by the flagellates were compared. All flagellate species regenerated comparable amounts of nitrogen, which was thought to be due to their similar internal C/N ratios. There was, however, interspecies variation with regard to phosphorus regeneration: the two faster-growing species (Paraphysomonas imperforata and Bodo designis) released significantly more phosphorus than the two slower-growing species (Stephanoeca diplocostata and Jakoba libera). The observed differences were thought to have been influenced by a combination of life cycle strategies and internal C/P ratios.

Journal Article↗
PubMed1999

A phase variant of Azospirillum lipoferum lacks a polar flagellum and constitutively expresses mechanosensing lateral flagella.

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.

Azospirillum↗
PubMed1999

Bacterivory rate estimates and fraction of active bacterivores in natural protist assemblages from aquatic systems

Unlike the fraction of active bacterioplankton, the fraction of active bacterivores (i.e., those involved in grazing) during a specified time period has not been studied yet. Fractions of protists actively involved in bacterivory were estimated assuming that the distributions of bacteria and fluorescently labeled bacteria (FLB) ingested by protists follow Poisson distributions. Estimates were compared with experimental data obtained from FLB uptake experiments. The percentages of protists with ingested FLB (experimental) and the estimates obtained from Poisson distributions were similar for both flagellates and ciliates. Thus, the fraction of protists actively grazing on natural bacteria during a given time period could be estimated. The fraction of protists with ingested bacteria depends on the incubation time and reaches a saturating value. Aquatic systems with very different characteristics were analyzed; estimates of the fraction of protists actively grazing on bacteria ranged from 7 to 100% in the studied samples. Some nanoflagellates appeared to be grazing on specific bacterial sizes. Evidence indicated that there was no discrimination for or against bacterial surrogates (i.e., FLB); also, bacteria were randomly encountered by bacterivorous protists during these short-term uptake experiments. These analyses made it possible to estimate the ingestion rates from FLB uptake experiments by counting the number of flagellates containing ingested FLB. These results represent the first reported estimates of active bacterivores in natural aquatic systems; also, a proposed protocol for estimating in situ ingestion rates by protists represents a significant improvement and simplification to the current protocol and avoids the tedious work of counting the number of ingested FLB per protist.

Journal Article↗
PubMed2002

Unveiling the organisms behind novel eukaryotic ribosomal DNA sequences from the ocean.

Despite the fact that the smallest eukaryotes (cells less than 5 micro m in diameter) play key roles in marine food webs, particularly in open oligotrophic areas, the study of their in situ diversity started just one year ago. Perhaps the most remarkable finding of the most recent studies has been the discovery of completely new phylogenetic lineages, such as novel clades belonging to the stramenopile and alveolate phyla. The two new groups account for a significant fraction of clones in genetic libraries from North Atlantic, equatorial Pacific, Antarctic, and Mediterranean Sea waters. However, the identities and ecological relevance of these organisms remain unknown. Here we investigate the phylogenetic relationships, morphology, in situ abundance, and ecological role of novel stramenopiles. They form at least eight independent clades within the stramenopile basal branches, indicating a large phylogenetic diversity within the group. Two lineages were visualized and enumerated in field samples and enrichments by fluorescent in situ hybridization using specific rRNA-targeted oligonucleotide probes. The targeted organisms were 2- to 3- micro m-diameter, round-shaped, nonpigmented flagellates. Further, they were found to be bacterivorous. One lineage accounted for up to 46% (average during an annual cycle, 19%) of heterotrophic flagellates in a coastal environment, providing evidence that novel stramenopiles are important and unrecognized components of the total stock of bacterial grazers.

Animals↗
PubMed2006

Direct and indirect effects of protist predation on population size structure of a bacterial strain with high phenotypic plasticity.

We studied the impact of grazing and substrate supply on the size structure of a freshwater bacterial strain (Flectobacillus sp.) which showed pronounced morphological plasticity. The cell length varied from 2 to >40 microm and encompassed rods, curved cells, and long filaments. Without grazers and with a sufficient substrate supply, bacteria grew mainly in the form of medium-sized rods (4 to 7 microm), with a smaller proportion (<10%) of filamentous forms. Grazing experiments with the bacterivorous flagellate Ochromonas sp. showed that freely suspended cells of <7 microm were highly vulnerable to grazers, whereas filamentous cells were resistant to grazing and became enriched during predation. A comparison of long-term growth in carbon-limited chemostats with and without grazers revealed that strikingly different bacterial populations developed: treatments with flagellates were composed of >80% filamentous cells. These attained a biomass comparable to that of populations in chemostats without grazers, which were composed of medium-sized rods and c-shaped cells. Carbon starvation resulted in a fast decrease in cell length and a shift towards small rods, which were highly vulnerable to grazing. Dialysis bag experiments in combination with continuous cultivation revealed that filament formation was significantly enhanced even without direct contact of bacteria with bacterivores and was thus probably stimulated by grazer excretory products.

Animals↗
PubMed2005

Unique mitochondrial genome structure in diplonemids, the sister group of kinetoplastids.

Kinetoplastid flagellates are characterized by uniquely massed mitochondrial DNAs (mtDNAs), the kinetoplasts. Kinetoplastids of the trypanosomatid group possess two types of mtDNA molecules: maxicircles bearing protein and mitoribosomal genes and minicircles specifying guide RNAs, which mediate uridine insertion/deletion RNA editing. These circles are interlocked with one another to form dense networks. Whether these peculiar mtDNA features are restricted to kinetoplastids or prevail throughout Euglenozoa (euglenids, diplonemids, and kinetoplastids) is unknown. Here, we describe the mitochondrial genome and the mitochondrial ultrastructure of Diplonema papillatum, a member of the diplonemid flagellates, the sister group of kinetoplastids. Fluorescence and electron microscopy show a single mitochondrion per cell with an ultrastructure atypical for Euglenozoa. In addition, DNA is evenly distributed throughout the organelle rather than compacted. Molecular and electron microscopy studies distinguish numerous 6- and 7-kbp-sized mitochondrial chromosomes of monomeric circular topology and relaxed conformation in vivo. Remarkably, the cox1 gene (and probably other mitochondrial genes) is fragmented, with separate gene pieces encoded on different chromosomes. Generation of the contiguous cox1 mRNA requires trans-splicing, the precise mechanism of which remains to be determined. Taken together, the mitochondrial gene/genome structure of Diplonema is not only different from that of kinetoplastids but unique among eukaryotes as a whole.

Animals↗
PubMed2006

Listeria monocytogenes flagella are used for motility, not as adhesins, to increase host cell invasion.

Flagellar structures contribute to the virulence of multiple gastrointestinal pathogens either as the effectors of motility, as adhesins, or as a secretion apparatus for virulence factors. Listeria monocytogenes is a food-borne, gram-positive pathogen that uses flagella to increase the efficiency of epithelial cell invasion (A. Bigot, H. Pagniez, E. Botton, C. Frehel, I. Dubail, C. Jacquet, A. Charbit, and C. Raynaud, Infect. Immun. 73:5530-5539, 2005; L. Dons, E. Eriksson, Y. Jin, M. E. Rottenberg, K. Kristensson, C. N. Larsen, J. Bresciani, and J. E. Olsen, Infect. Immun. 72:3237-3244, 2004). In this study, we aimed to elucidate the mechanism by which flagella contribute to L. monocytogenes invasion. To examine the role of flagella as adhesins, invasion and adhesion assays were performed with flagellated motile and nonmotile bacteria and nonflagellated bacteria. We observed that flagellated but nonmotile bacteria do not adhere to or invade human epithelial cells more efficiently than nonflagellated bacteria. These results indicated that flagella do not function as adhesins to enhance the adhesion of L. monocytogenes to targeted host cells. Instead, it appears that motility is important for tissue culture invasion. Furthermore, we tested whether motility contributes to early colonization of the gastrointestinal tract using a competitive index assay in which mice were infected orally with motile and nonmotile bacteria in a 1:1 ratio. Differential bacterial counts demonstrated that motile bacteria outcompete nonmotile bacteria in the colonization of the intestines at early time points postinfection. This difference is also reflected in invasion of the liver 12 h later, suggesting that flagellum-mediated motility enhances L. monocytogenes infectivity soon after bacterial ingestion in vivo.

Adhesins, Bacterial↗
PubMed1985

Identification and occurrence of Vibrio cholerae flagellar core proteins in isolated outer membrane.

Sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis of outer membranes from a flagellated and an isogenic nonflagellated strain of Vibrio cholerae (classical, Inaba) suggested that two proteins were absent from the nonflagellated strain. Immunoblot examination of such preparations demonstrated that two proteins, present only in outer membrane from the flagellated strain, were associated with flagella. Analysis of purified flagellar cores from strains CA401 and N16961 (El Tor, Inaba) by electron microscopy, sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis, and immunoblotting showed that these two proteins, with apparent molecular weights of 47,000 and 49,000, composed the flagellar core. Antiserum specific for flagellar core proteins did not agglutinate or inhibit the motility of intact V. cholerae. These latter findings suggested that, for intact cells, the flagellar core proteins are not accessible to antibody.

Antibodies, Bacterial↗
PubMed1986

Antigenicity of Campylobacter jejuni flagella.

We studied the antigenicity of a wild-type flagellate and motile (F+M+) Campylobacter jejuni strain (81116) and two daughter mutants, one flagellate and immotile (F+M-) and one aflagellate and immotile (F-M-). By sodium dodecyl sulfate-polyacrylamide gel electrophoresis of acid-extracted surface proteins, a 63-kilodalton (kDa) band identified from sheared flagella as the flagellar protein was present in the F+M+ and F+M- strains but not in the F-M- strain. No other differences in protein profile among the three strains were noted. By Western blotting, serum from rabbits immunized with either the F+M+ or F-M- strain detected a 63-kDa protein in the F+M+ and F+M- strains but not in the F-M- strain. That the F-M- antiserum recognized the 63-kDa band suggests that small amounts of this protein or a cross-reacting antigen is present on the F-M- strain. By counterimmunoelectrophoresis of the acid-extracted preparations with immune sera, all three strains were found to share three major antigens, but a fourth antigen with a net positive charge was present only in the F+M+ and F+M- strains. Antisera to five C. jejuni and two Campylobacter fetus strains recognized the 63-kDa protein of purified F+M+ flagella in Western blots, demonstrating a common antigen is present, but enzyme-linked immunosorbent assay results suggest that the sharing of this antigen among Campylobacter strains is variable.

Antigens, Bacterial↗