SEARCH · PubMed Health

Results for “FLAGELLA”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 37 records · Page 2Linked to original sources

PubMed1991

The bent-end morphology of Treponema phagedenis is associated with short, left-handed, periplasmic flagella.

Treponema phagedenis Kazan 5 is a spirochete with multiple periplasmic flagella attached near each end of the cell cylinder. Dark-field microscopy revealed that most of the cell is right-handed (helix diameter, 0.23 micron; helix pitch, 1.74 microns), and the ends appear bent. These ends could move and gyrate while the central part of the cell remained stationary. The present study examines the basis for the bent-end characteristic. Motility mutants deficient in periplasmic flagella were found to lack the bent ends, and spontaneous revertants to motility regained the periplasmic flagella and bent-end characteristic. The length of the bent ends (2.40 microns) was found to be similar to the length of the periplasmic flagella as determined by electron microscopy (2.50 microns). The helix diameter of the bent ends was 0.57 micron, and the helix pitch of the bent ends was 1.85 microns. The periplasmic flagella were short relative to the length of the cells (15 microns) and, in contrast to the reports of others, did not overlap in the center of the cell. Similar results were found with T. phagedenis Reiter. The results taken together indicate that there is a causal relationship between the bent-end morphology and the presence of short periplasmic flagella. We report the first three-dimensional description of spirochete periplasmic flagella. Dark-field microscopy of purified periplasmic flagella revealed that these organelles were left-handed (helix diameter, 0.36 microns; helix pitch, 1.26 microns) and only 1 to 2 wavelengths long. Because of a right-handed cell cylinder and left-handed periplasmic flagella along with bent ends having helix diameters greater than those of either the cell cylinder or periplasmic flagella, we conclude that there is a complex interaction of the periplasmic flagella and the cell cylinder to form the bent ends. The results are discussed with respect to a possible mechanism of T. phagedenis motility.

Cell Movement↗

PubMed1966

Some singular properties of bacterial flagella, with special reference to monotrichous forms.

Roberts, F. F., Jr. (University of Maryland, College Park), and R. N. Doetsch. Some singular properties of bacterial flagella, with special reference to monotrichous forms. J. Bacteriol. 91:414-421. 1966.-Heat (60 C for 30 min), 10 m acetamide, and 8 m urea all brought about rapid and complete dissolution of flagella from monotrichous bacteria; hence, these flagella respond similarly to those of peritrichous forms. Chloramphenicol (10(3) mug/ml) inhibited regeneration of flagella in all peritrichously flagellated cultures; however, monotrichous forms were able to regenerate their flagella in a concentration 10(2) times that required to inhibit multiplication. Peritrichous bacteria did not synthesize flagella when infected by lytic bacteriophages. In these experiments, the time from infection to lysis was sufficient for uninfected controls to resynthesize their flagella. Monotrichous bacteria, however, in all but one instance, were able to resynthesize their flagella before lysis occurred. A study of flagella resynthesis in a non-nutritive milieu indicated that only a small amount of flagellum precursor is present in any given cell. The effect of temperature on synthesis of flagella indicated that, although some bacteria multiply and are motile at a given temperature, they are unable to resynthesize their flagella at that same temperature. This strongly suggests that initial flagellum synthesis and flagellum regeneration are not necessarily identical processes.

Amides↗

PubMed1984

Morphology, function and isolation of halobacterial flagella.

Halobacterium halobium has right-handed helical flagella. During the logarithmic phase of growth, cells are predominantly monopolar, whereas in the stationary phase they are mostly bipolarly flagellated. The flagellar bundle consists of several filaments. Halobacteria swim forward by clockwise and backwards by counterclockwise rotation of their flagella. The flagellar bundle does not fly apart when the sense of rotation changes. In addition to the flagella attached to the cells, large amounts of loose flagella, which aggregate into thick super-flagella, can be observed at all phases of growth. During stationary phase, the production of these super-flagella, which are generally 10 to 20 times longer than the cell body, is significantly higher. Dissociation and association by high temperature and differential centrifugation allow the isolation of pure flagella. Three different protein bands, of 23,500, 26,500 and 31,500 apparent molecular weights, are seen on sodium dodecyl sulphate/polyacrylamide gels. Antibodies against halobacterial flagella were produced in chicken; these antibodies interact with the flagella even in 4 M-NaCl. Rotation of tethered cells demonstrates that Halobacteria move due to the rotation of the flagella.

Bacterial Proteins↗

PubMed1977

Formation and function of Vibrio parahaemolyticus lateral flagella.

Formation of the lateral flagella (L-flagella) of Vibrio parahaemolyticus was studied immunologically, using specific antiserum against L-flagella. On solid medium, L-flagella were formed at both high (37 degrees C) and low (25 degrees C) temperatures, although at high temperatures they became dissociated from the cells and decomposed in the medium. L-flagella were not formed in liquid or soft-agar medium. Formation of L-flagella was decreased by lowering the pH of the medium and repressed by transferring the cells from solid medium to liquid medium. Mutants possessing L-flagella but not a polar monotrichous flagellum (M-flagellum) swarmed on solid medium, whereas mutants were grown on solid medium and then transfered to liquid medium, the cells oscillated until they lost L-flagella. It is postulated that L-flagella are locomotive organelles on solid medium and in some cases also in liquid medium, whereas M-flagella are locomotive organelles only in liquid medium.

Culture Media↗

PubMed1988

Formation of flagella during interphase in secondary spermatocytes from Xenopus laevis in vitro.

In cell culture, single motile flagella, 1 micron in length, were observed to grow from secondary spermatocytes of Xenopus laevis within 2-3 hours after telophase I, at 22 degrees C. About 90% of the secondary spermatocytes formed flagella as observed by phase-contrast microscopy. The flagella grew up to 2-6 microns in length during interphase II, which lasted about 18 hours. The presence of the "9 + 2" microtubular structure of the flagellar axonemes of secondary spermatocytes was confirmed by electron microscopy. When chromosomal condensation began (prophase II), the flagella were resorbed into the cells and, after the second meiotic division, a flagellum was formed again by each of the round spermatids. Thus, there appears to be a close relationship between the meiotic division cycle and the formation of flagella. The possible contribution of Sertoli cells to the formation of flagella in secondary spermatocytes was examined by reducing the number of Sertoli cells to less than ten per culture. Under these conditions, flagella formed in secondary spermatocytes with very high efficiency. It is very likely that secondary spermatocytes form flagella in vivo, since the secondary spermatocytes were observed to have flagella immediately after dissociation of the testes.

Animals↗

PubMed1990

Cell body and flagellar agglutinins in Chlamydomonas reinhardtii: the cell body plasma membrane is a reservoir for agglutinins whose migration to the flagella is regulated by a functional barrier.

Fertilization in Chlamydomonas reinhardtii is initiated when gametes of opposite mating types adhere to each other via adhesion molecules (agglutinins) on their flagella. Adhesion leads to loss of active agglutinins from the flagella and recruitment of new agglutinins from a pool associated with the cell body. We have been interested in determining the precise cellular location of the pool and learning more about the relationship between agglutinins in the two domains. In the studies reported here we describe methods for purification of mt+ cell body agglutinins by use of ammonium sulfate precipitation, chromatography (molecular sieve, ion exchange, and hydrophobic interaction), and sucrose gradient centrifugation. About 90% of the total agglutinins were associated with the cell body and the remainder were on the flagella. Cell body agglutinins were indistinguishable from mt+ flagellar agglutinins by SDS-PAGE, elution properties on a hydrophobic interaction column, and in sedimentation properties on sucrose gradients. The nonadhesiveness of cell bodies suggested that the cell body agglutinins would be intracellular, but our results are not consistent with this interpretation. We have demonstrated that brief trypsin treatment of deflagellated gametes destroyed all of the cell body agglutinins and, in addition, we showed that the cell body agglutinins were accessible to surface iodination. These results indicated that C. reinhardtii agglutinins have a novel cellular disposition: active agglutinins, representing approximately 10% of the total cellular agglutinins, are found only on the flagella, whereas the remaining 90% of these molecules are on the external surface of the cell body plasma membrane in a nonfunctional form. This segregation of cell adhesion molecules into distinct membrane domains before gametic interactions has been demonstrated in sperm of multicellular organisms and may be a common mechanism for sequestering these critical molecules until gametes are activated for fusion. In experiments in which surface-iodinated cell bodies were permitted to regenerate new flagella, we found that the agglutinins (as well as the 350,000 Mr, major flagellar membrane protein) on the newly regenerated flagella were iodinated. These results indicate that proteins destined for the flagella can reside on the external surface of the cell body plasma membrane and are recruited onto newly forming flagella as well as onto preexisting flagella during fertilization.

Agglutinins↗

PubMed1988

Genetic analysis of long-flagella mutants of Chlamydomonas reinhardtii.

The length of the flagella of Chlamydomonas reinhardtii cells is tightly regulated; both short-flagella and long-flagella mutants have been described. This report characterizes ten long-flagella mutants, including five newly isolated mutants, to determine the number of different loci conferring this phenotype, and to study interactions of mutants at different loci. The mutants, each of which was recessive in heterozygous diploids with wild type, fall into three unlinked complementation groups. One of these defines a new gene, lf3, which maps near the centromere of linkage group I. The flagellar length distributions in populations of each mutant were broad, with the longest flagella measuring four times the length of the longest flagella seen on wild-type cells. Each of the ten mutants had defective flagellar regrowth after amputation. Some of the mutants showed no regrowth within the time required for wild-type cells to regenerate flagella completely. Other mutants had subpopulations with rapid regeneration kinetics, and subpopulations with no observable regeneration. The mutants were each crossed to wild type to form temporary quadriflagellate, dikaryon cells; in each case the long flagella were rapidly shortened in the presence of the wild-type cytoplasm, demonstrating that the mutants were recessive, and that length control could be exerted on already assembled flagella.

Chlamydomonas↗

PubMed2003

Pseudomonas aeruginosa flagella activate airway epithelial cells through asialoGM1 and toll-like receptor 2 as well as toll-like receptor 5.

The distribution of specific toll-like receptors and components of the signaling pathways activated by Pseudomonas aeruginosa flagella were studied in airway epithelial cells. Initially flagella bound to the apical surface of polarized epithelial cells, where they prominently colocalized with asialoGM1. By 4 h of exposure to flagella, toll-like receptor (TLR)5 expression was induced, mobilized to the apical surface of the cells, and colocalized with superficial flagella. Interleukin-8 expression in airway cells was activated by flagella through induction of Ca(2+) fluxes, Src, Ras, and extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase and nuclear factor-kappaB activation, a pathway previously associated with asialoGM1-mediated stimuli. There was evidence for participation of asialoGM1 and TLR2 as well as TLR5 in the response to flagella, and increased asialoGM1 correlated directly with increased signaling. TLR2 DN or TLR5 DN mutations inhibited interleukin-8 induction by 78% and 35%, respectively (P < 0.001 for each). The participation of TLR2 as well as TLR5 was confirmed in Chinese hamster ovary cells transfected with either human TLR2 or TLR5 in which flagella activated a nuclear factor-kappaB-luciferase reporter to the same extent. Flagella signaling in airway cells can be initiated by interactions with asialoGM1 and TLR2 as well as by activation of TLR5. The availability of exposed receptors on the apical surface of polarized airway epithelial cells is a major factor in the activation of signaling pathways by flagella.

Animals↗

PubMed1992

Systemic and topical protection studies using Pseudomonas aeruginosa flagella in an ocular model of infection.

Purified flagella from P. aeruginosa ATCC 19660 were used for active, passive, or topical immunization prior to corneal challenge with strain 19660. At 30 days post-infection, a significant number of mice actively or passively immunized with flagella and infected with the homologous bacterial strain were protected from ocular disease when compared to control animals. In topical immunization studies, premixing of 19660 flagella with the bacterial inoculum prior to ocular challenge with strain 19660, provided results similar to those of the active or passive immunization studies. A reduced lipopolysaccharide (LPS:1 E.U./mg) flagella preparation was also produced and used similarly. Again, significant protection was achieved in mice immunized by flagella regardless of the immunization route. An in vitro adherence assay also was performed to examine quantitatively the effect of exogenously applied flagella, or an antiflagella monoclonal antibody (MAb) on bacterial adhesion. Premixing of the bacterial inoculum with flagella or the MAb prior to applying it topically to corneas in organ culture all significantly inhibited bacterial binding. These results strongly suggest that significant ocular protection is achieved with either active or passive immunization, or premixing of the bacterial inoculum with flagella from strain 19660 prior to ocular challenge with the homologous bacterial strain. They also indicate that topical application of flagella or antiflagella MAb provide protection against ocular disease by decreasing bacterial adhesion to cornea.

Animals↗

PubMed1996

Functions of bacterial flagella.

Many bacterial species are motile by means of flagella. The structure and implantation of flagella seems related to the specific environments the cells live in. In some cases, the bacteria even adapt their flagellation pattern in response to the environmental conditions they encounter. Swarming cell differentiation is a remarkable example of this phenomenon. Flagella seem to have more functions than providing motility alone. For many pathogenic species, studies have been performed on the contribution of flagella to the virulence, but the result is not clear in all cases. Flagella are generally accepted as being important virulence factors, and expression and repression of flagellation and virulence have in several cases been shown to be linked. Providing motility is always an important feature of flagella of pathogenic bacteria, but adhesive and other properties also have been attributed to these flagella. In nonpathogenic bacterial colonization, flagella are important locomotive and adhesive organelles as well. In several cases where competition between several bacterial species exists, motility by means of flagella is shown to provide a specific advantage for a bacterium. This review gives an overview of studies that have been performed on the significance of flagellation in a wide variety of processes where flagellated bacteria are involved.

Animal Population Groups↗

PubMed1965

FLAGELLA OF SALMONELLA TYPHIMURIUM SPHEROPLASTS.

Vaituzis, Z. (University of Maryland, College Park), and R. N. Doetsch. Flagella of Salmonella typhimurium spheroplasts. J. Bacteriol. 89:1586-1593. 1965.-The flagella of penicillin-induced spheroplasts of Salmonella typhimurium were examined by electron and light microscopy. The process of spheroplast formation was followed for a period of 20 hr from its inception. Flagella were found to be confined to those areas of the spheroplast where cell-wall fragments remained. Flagella disappeared as the spheroplasts aged. Spheroplasts produced from nonflagellated organisms were found incapable of synthesizing flagella. Upon inactivation of the penicillin, however, flagella again were synthesized by spheroplasts during reversion to their original rod form. Flagella formation, it is suggested, is dependent on prior synthesis of the normal cell wall. The morphology of the microorganisms at the time of appearance of new flagella is described.

Cell Physiological Phenomena↗

PubMed1997

Flagella are a positive predictor for virulence in Legionella.

Pathogenesis of Legionnaires>> disease is strictly related to the ability of the legionellae to infect phagocytic cells, yet surface markers of virulence in Legionella isolates are currently unknown. Rabbit antibodies raised against purified flagella of Legionella pneumophila serogroup 1 recognized a total of 24 of 30 laboratory-maintained isolates of L. pneumophila serogroups 1-15 and 16 of 24 other Legionella species tested by rapid immunoblot and indirect immunofluorescence assay. All isolates possessing flagella detectable with these anti-flagella antibodies, regardless of species, were capable of infecting Hartmannella vermiformis. Isolates lacking immunologic cross-reactivity were shown to lack purifiable flagella. The majority of aflagellate isolates were not motile and failed to multiply intracellularly in co-culture with Hartmannella vermiformis. Some isolates characterized as aflagellate when harvested from BCYE agar were able to multiply in amoebae, and flagella were subsequently detectable by immunologic methods. These data suggest that lack of immunologic recognition of flagella in laboratory-maintained isolates of Legionella is due to their attenuation and a corresponding loss of expression of flagella. More importantly, the presence of flagella can serve as a positive predictive marker for strain virulence and is useful in determining the virulence status of Legionella isolates.

Animals↗

PubMed2002

Lateral flagella of Aeromonas species are essential for epithelial cell adherence and biofilm formation.

Mesophilic Aeromonas strains express a single polar flagellum in all culture conditions and produce lateral flagella on solid media. Such hyperflagellated cells demonstrate increased adherence. Nine lateral flagella genes, lafA-U for Aeromonas hydrophila, and four Aeromonas caviae genes, lafA1, lafA2, lafB and fliU, were isolated. Mutant characterization, nucleotide and N-terminal sequencing demonstrated that the A. hydrophila and A. caviae lateral flagellins were almost identical, but were distinct from their polar flagellum counterparts. The aeromonad lateral flagellins exhibited higher molecular masses on SDS-PAGE, and this aberrant migration was thought to result from post-translational modification through glycosylation. Mutation of the Aeromonas lafB, lafS or both A. caviae lateral flagellins caused the loss of lateral flagella and a reduction in adherence and biofilm formation. Mutations in lafA1, lafA2, fliU or lafT resulted in strains that expressed lateral flagella, but had reduced adherence levels. Mutation of the lateral flagella loci did not affect polar flagellum synthesis, but the polarity of the transposon insertions on the A. hydrophila lafTlU genes resulted in non-motility. However, mutations that abolished polar flagellum production also inhibited lateral flagella expression. We conclude that Aeromonas lateral flagella: (i) play a role in adherence and biofilm formation; (ii) are distinct from the polar flagellum; (iii) synthesis is dependent upon the presence of a polar flagellum filament; and (iv) that the motor proteins of the polar and lateral flagella systems appear to be shared.

Aeromonas↗

PubMed1997

Transport of a novel complex in the cytoplasmic matrix of Chlamydomonas flagella.

Proteins necessary for maintenance and function of eukaryotic flagella are synthesized in the cell body. Transport of the inner dynein arm subunit p28(IDA4) in Chlamydomonas flagella requires the activity of the kinesin KHP1(FLA10), a protein inactive at restrictive temperature in fla10, a temperature-dependent mutant of flagellar assembly. To identify other molecules involved in active transport of inner dynein arms within flagella we searched for polypeptides of the cytoplasmic matrix of flagella that fulfill two conditions: they bind to p28 and require the activity of KHP1 to be present in flagella. We found that the cytoplasmic matrix of flagella contains a previously unidentified "17S" complex of at least 13 polypeptides that in part is associated with p28. The 17S complex is present at permissive but not at restrictive temperature in fla10 flagella. It also turns over in the cytoplasmic matrix more frequently than dynein arms within the axoneme. This evidence suggests that the 17S complex transports precursors of inner dynein arms within flagella.

Algal Proteins↗

PubMed1965

Electron microscopy of bundled flagella of the curly mutant of Salmonella abortivoequina.

Mitani, Michiko (National Institute of Genetics, Mishima, Japan), and Tetsuo Iino. Electron microscopy of bundled flagella of the curly mutant of Salmonella abortivoequina. J. Bacteriol. 90:1096-1101. 1965.-The arrangement of flagella was observed by dark-field and electron microscopy in three strains of Salmonella abortivoequina, namely, normal flagellar, curly flagellar, and paralyzed curly flagellar strains. With dark-field microscopy, bundled flagella could be seen in 5 to 10% of actively moving normal or curly mutant cells. Under the electron microscope, a great many bundled flagella were observed in the curly mutant strain, but in the normal strain most of the flagella were dissociated or the bundles were rather loose and irregular. Normal flagella seem to separate easily during the process of preparation, but not the curly ones. Single flagella were found to run parallel with each other and to form a bundle consisting of five or more flagella; the bundle was spirally gyrating, with the characteristic flagellar wave. It is thought that the bundle observed with the electron microscope corresponds to that observed under the dark-field microscope. Further, the marked decrease of bundle formation in the paralyzed curly mutant cells suggests that bundle formation is not caused by curly flagellar structure per se, but corresponds to the mode of locomotion of peritrichously flagellated bacteria.

Flagella↗

PubMed1965

Basal structure and attachment of flagella in cells of Proteus vulgaris.

Abram, Dinah (Purdue University, Lafayette, Ind.), Henry Koffler, and A. E. Vatter. Basal structure and attachment of flagella in cells of Proteus vulgaris. J. Bacteriol. 90:1337-1354. 1965.-The attachment of flagella to cells of Proteus vulgaris was studied electron microscopically with negatively stained and shadow-cast preparations of ghosts from standard cultures and from special cultures that produced "long forms." The flagellum, the basal portion of which is hooked, arises within the cell from a nearly spherical structure, 110 to 140 A in diameter. This structure appears to be associated with the cytoplasmic membrane; it may be a part of the membrane or a separate entity that lies just beneath the membrane. Flagella associated with cell walls free from cytoplasmic membrane frequently have larger bodies, 200 to 700 A in diameter, associated with their base. These structures probably consist at least partly of fragments of the cytoplasmic membrane, a portion of which folds around a smaller structure. Flagella in various stages of development were observed in long forms of P. vulgaris cells grown at low temperature. The basal structure of these flagella was similar to that of the long or "mature" flagella. Strands connecting the basal structures were observed in ghosts of long forms; these strands appear to be derived from the cytoplasmic membrane. Flagella were found to be attached to fragments of cell wall and to cytoplasmic membrane in a similar manner as they are attached to ghosts. In isolates of flagella that have been separated from the cells mechanically, the organelles often terminate in hooks which almost always appear naked, but have a different fine structure than the flagellum proper.

Flagella↗

PubMed1966

Attachment and structural features of flagella of certain bacilli.

Abram, Dinah (Purdue University, Lafayette, Ind.), A. E. Vatter, and Henry Koffler. Attachment and structural features of flagella of certain bacilli. J. Bacteriol. 91:2045-2068. 1966.-The attachment of flagella to cells of various mesophilic and thermophilic strains of Bacillus was studied electron microscopically. Studies of ghost cells and membrane fragments indicate that flagella are connected to the cytoplasmic membrane. Flagella removed from cells mechanically, during autolysis, or by phage lysis, have attached to the base of their proximal hooks material that is heterogeneous in character. In part, this material consists of cytoplasmic membrane; its varied shape appears to be caused by the folding of the membrane around the proximal end of the flagellum at the site of attachment. It is uncertain whether this material represents a real structure or an artifact. Highresolution microscopy reveals differences in the fine structure of intact flagella of the various strains studied. The proximal hook and the flagellar filament are distinct in morphology and fine structure. A specialized structure is associated with the hook of flagella of B. brevis and B. circulans. The filament of flagella of B. stearothermophilus 2184 has two regions that show marked differences in the manner in which the subunits appear to be organized. No correlation was found between the site of origin of flagella and the location of reduced tellurite when the reduction of potassium tellurite was used to indicate the loci of enzymatic respiratory activities.

Bacillus↗

PubMed2000

Calcium regulation of microtubule sliding in reactivated sea urchin sperm flagella.

The changes in the bending pattern of flagella induced by an increased intracellular Ca(2+) concentration are caused by changes in the pattern and velocity of microtubule sliding. However, the mechanism by which Ca(2+) regulates microtubule sliding in flagella has been unclear. To elucidate it, we studied the effects of Ca(2+) on microtubule sliding in reactivated sea urchin sperm flagella that were beating under imposed head vibration. We found that the maximum microtubule sliding velocity obtainable by imposed vibration, which was about 170-180 rad/second in the presence of 250 microM MgATP and <10(-9) M Ca(2+), was decreased by 10(-6)-10(-5) M Ca(2+) by about 15-20%. Similar decrease of the sliding velocity was observed at 54 and 27 microM MgATP. The Ca(2+)-induced decrease of the sliding velocity was due mainly to a decrease in the reverse bend angle. When the plane of beat was artificially rotated by rotating the plane of vibration of the pipette that held the sperm head, the asymmetric bending pattern also rotated at 10(-5) M Ca(2+) as well as at <10(-9) M Ca(2+). The rotation of the bending pattern was observed at MgATP higher than 54 microM ( approximately 100 microM ATP). These results indicate that the Ca(2+)-induced decrease of the sliding velocity is mediated by a rotatable component or components (probably the central pair) at high MgATP, but is not due to specific dynein arms on particular doublets. We further investigated the effects of a mild trypsin treatment and of trifluoperazine on the Ca(2+)-induced decrease in sliding velocity. Axonemes treated for 3 minutes with a low concentration (0.1 microgram/ml) of trypsin beat with a more symmetrical waveform than before the treatment. Also, their microtubule sliding velocity and reverse bend angle were not affected by high Ca(2+) concentrations. Trifluoperazine (25-50 microM) had no effect on the decrease of the sliding velocity in beating flagella at 10(-5) M Ca(2+). However, the flagella that had been 'quiescent' at 10(-4) M Ca(2+) resumed asymmetrical beating following an application of 10-50 microM trifluoperazine. In such beating flagella, both the sliding velocity and the reverse bend angle were close to their respective values at 10(-5) M Ca(2+). Trypsin treatment induced a similar recovery of beating in quiescent flagella at 10(-)(4) M Ca(2+), albeit with a more symmetrical waveform. These results provide first evidence that, at least at ATP concentrations higher than approximately 100 microM, 10(-6)-10(-5) M Ca(2+) decreases the maximum sliding velocity of microtubules in beating flagella through a trypsin-sensitive regulatory mechanism which possibly involves the central pair apparatus. They also suggest that calmodulin may be associated with the mechanism underlying flagellar quiescence induced by 10(-4) M Ca(2+).

Animals↗