Evidence for symmetry in the elementary process of bidirectional torque generation by the bacterial flagellar motor

PubMed Central

Nakamura, Shuichi; Kami-ike, Nobunori; Yokota, Jun-ichi P.; Minamino, Tohru; Namba, Keiichi

2010-01-01

The bacterial flagellar motor can rotate in both counterclockwise (CCW) and clockwise (CW) directions. It has been shown that the sodium ion-driven chimeric flagellar motor rotates with 26 steps per revolution, which corresponds to the number of FliG subunits that form part of the rotor ring, but the size of the backward step is smaller than the forward one. Here we report that the proton-driven flagellar motor of Salmonella also rotates with 26 steps per revolution but symmetrical in both CCW and CW directions with occasional smaller backward steps in both directions. Occasional shift in the stepping positions is also observed, suggesting the frequent exchange of stators in one of the 11–12 possible anchoring positions around the rotor. These observations indicate that the elementary process of torque generation by the cyclic association/dissociation of the stator with every FliG subunit along the circumference of the rotor is symmetric in CCW and CW rotation even though the structure of FliG is highly asymmetric and suggests a 180° rotation of a FliG domain for the rotor-stator interaction to reverse the direction of rotation. PMID:20876126

Structure of the torque ring of the flagellar motor and the molecular basis for rotational switching.

PubMed

Lee, Lawrence K; Ginsburg, Michael A; Crovace, Claudia; Donohoe, Mhairi; Stock, Daniela

2010-08-19

The flagellar motor drives the rotation of flagellar filaments at hundreds of revolutions per second, efficiently propelling bacteria through viscous media. The motor uses the potential energy from an electrochemical gradient of cations across the cytoplasmic membrane to generate torque. A rapid switch from anticlockwise to clockwise rotation determines whether a bacterium runs smoothly forward or tumbles to change its trajectory. A protein called FliG forms a ring in the rotor of the flagellar motor that is involved in the generation of torque through an interaction with the cation-channel-forming stator subunit MotA. FliG has been suggested to adopt distinct conformations that induce switching but these structural changes and the molecular mechanism of switching are unknown. Here we report the molecular structure of the full-length FliG protein, identify conformational changes that are involved in rotational switching and uncover the structural basis for the formation of the FliG torque ring. This allows us to propose a model of the complete ring and switching mechanism in which conformational changes in FliG reverse the electrostatic charges involved in torque generation.

Loose coupling in the bacterial flagellar motor

PubMed Central

Boschert, Ryan; Adler, Frederick R.; Blair, David F.

2015-01-01

Physiological properties of the flagellar rotary motor have been taken to indicate a tightly coupled mechanism in which each revolution is driven by a fixed number of energizing ions. Measurements that would directly test the tight-coupling hypothesis have not been made. Energizing ions flow through membrane-bound complexes formed from the proteins MotA and MotB, which are anchored to the cell wall and constitute the stator. Genetic and biochemical evidence points to a “power stroke” mechanism in which the ions interact with an aspartate residue of MotB to drive conformational changes in MotA that are transmitted to the rotor protein FliG. Each stator complex contains two separate ion-binding sites, raising the question of whether the power stroke is driven by one, two, or either number of ions. Here, we describe simulations of a model in which the conformational change can be driven by either one or two ions. This loosely coupled model can account for the observed physiological properties of the motor, including those that have been taken to indicate tight coupling; it also accords with recent measurements of motor torque at high load that are harder to explain in tight-coupling models. Under loads relevant to a swimming cell, the loosely coupled motor would perform about as well as a two-proton motor and significantly better than a one-proton motor. The loosely coupled motor is predicted to be especially advantageous under conditions of diminished energy supply, or of reduced temperature, turning faster than an obligatorily two-proton motor while using fewer ions. PMID:25825730

Modeling torque versus speed, shot noise, and rotational diffusion of the bacterial flagellar motor.

PubMed

Mora, Thierry; Yu, Howard; Wingreen, Ned S

2009-12-11

We present a minimal physical model for the flagellar motor that enables bacteria to swim. Our model explains the experimentally measured torque-speed relationship of the proton-driven E. coli motor at various pH and temperature conditions. In particular, the dramatic drop of torque at high rotation speeds (the "knee") is shown to arise from saturation of the proton flux. Moreover, we show that shot noise in the proton current dominates the diffusion of motor rotation at low loads. This suggests a new way to probe the discreteness of the energy source, analogous to measurements of charge quantization in superconducting tunnel junctions.

Proposed model for the flagellar rotary motor with shear stress transmission

PubMed Central

Mitsui, Toshio; Ohshima, Hiroyuki

2012-01-01

Most bacteria that swim are propelled by flagellar filaments, which are driven by a rotary motor powered by proton flux. The motor consists of the rotor and the stator. The stator consists of about 8 MotA-Mot B complex. There seems to be no definite information about the structure between the rotor and the stator, and it is examined whether the experimental data can be explained based upon the following assumptions. (a) There is viscoelastic medium between the rotor and the stator. (b) MotA-MotB complex has an electric dipole moment and produces shear stress in the electric field by a proton in the channel. Calculation results based upon these assumptions are in good agreement with the following experimental observations. (1) One revolution of the flagellar rotation consists of a constant number of steps. (2) The rotation velocity of the rotor is proportional to the trans-membrane potential difference. (3) When the rotational velocity of a flagellum is changed by adjusting the viscosity of the outer fluid, the torque for the cell to rotate a flagellum is practically constant but sharply decreases when the rotational velocity increases over a critical value. (4) The rotation direction remains the same when the sign of the electrochemical potential gradient is reversed. (5) The cell produces constant torque to rotate the flagellum even when the cell is rotated by externally applied torque. (6) A simple switch mechanism is proposed for chemotaxis. PMID:27493532

Modeling Torque Versus Speed, Shot Noise, and Rotational Diffusion of the Bacterial Flagellar Motor

PubMed Central

Mora, Thierry; Yu, Howard; Wingreen, Ned S.

2010-01-01

We present a minimal physical model for the flagellar motor that enables bacteria to swim. Our model explains the experimentally measured torque-speed relationship of the proton-driven E. coli motor at various pH and temperature conditions. In particular, the dramatic drop of torque at high rotation speeds (the “knee”) is shown to arise from saturation of the proton flux. Moreover, we show that shot noise in the proton current dominates the diffusion of motor rotation at low loads. This suggests a new way to probe the discreteness of the energy source, analogous to measurements of charge quantization in superconducting tunnel junctions. PMID:20366231

Impact of fluorescent protein fusions on the bacterial flagellar motor.

PubMed

Heo, M; Nord, A L; Chamousset, D; van Rijn, E; Beaumont, H J E; Pedaci, F

2017-10-03

Fluorescent fusion proteins open a direct and unique window onto protein function. However, they also introduce the risk of perturbation of the function of the native protein. Successful applications of fluorescent fusions therefore rely on a careful assessment and minimization of the side effects, but such insight is still lacking for many applications. This is particularly relevant in the study of the internal dynamics of motor proteins, where both the chemical and mechanical reaction coordinates can be affected. Fluorescent proteins fused to the stator of the Bacterial Flagellar Motor (BFM) have previously been used to unveil the motor subunit dynamics. Here we report the effects on single motors of three fluorescent proteins fused to the stators, all of which altered BFM behavior. The torque generated by individual stators was reduced while their stoichiometry remained unaffected. MotB fusions decreased the switching frequency and induced a novel bias-dependent asymmetry in the speed in the two directions. These effects could be mitigated by inserting a linker at the fusion point. These findings provide a quantitative account of the effects of fluorescent fusions to the stator on BFM dynamics and their alleviation- new insights that advance the use of fluorescent fusions to probe the dynamics of protein complexes.

Characterization of C-ring component assembly in flagellar motors from amino acid coevolution

PubMed Central

dos Santos, Ricardo Nascimento; Khan, Shahid

2018-01-01

Bacterial flagellar motility, an important virulence factor, is energized by a rotary motor localized within the flagellar basal body. The rotor module consists of a large framework (the C-ring), composed of the FliG, FliM and FliN proteins. FliN and FliM contacts the FliG torque ring to control the direction of flagellar rotation. We report that structure-based models constrained only by residue coevolution can recover the binding interface of atomic X-ray dimer complexes with remarkable accuracy (approx. 1 Å RMSD). We propose a model for FliM–FliN heterodimerization, which agrees accurately with homologous interfaces as well as in situ cross-linking experiments, and hence supports a proposed architecture for the lower portion of the C-ring. Furthermore, this approach allowed the identification of two discrete and interchangeable homodimerization interfaces between FliM middle domains that agree with experimental measurements and might be associated with C-ring directional switching dynamics triggered upon binding of CheY signal protein. Our findings provide structural details of complex formation at the C-ring that have been difficult to obtain with previous methodologies and clarify the architectural principle that underpins the ultra-sensitive allostery exhibited by this ring assembly that controls the clockwise or counterclockwise rotation of flagella. PMID:29892378

Conformational Spread in the Flagellar Motor Switch: A Model Study

PubMed Central

Maini, Philip K.; Berry, Richard M.; Bai, Fan

2012-01-01

The reliable response to weak biological signals requires that they be amplified with fidelity. In E. coli, the flagellar motors that control swimming can switch direction in response to very small changes in the concentration of the signaling protein CheY-P, but how this works is not well understood. A recently proposed allosteric model based on cooperative conformational spread in a ring of identical protomers seems promising as it is able to qualitatively reproduce switching, locked state behavior and Hill coefficient values measured for the rotary motor. In this paper we undertook a comprehensive simulation study to analyze the behavior of this model in detail and made predictions on three experimentally observable quantities: switch time distribution, locked state interval distribution, Hill coefficient of the switch response. We parameterized the model using experimental measurements, finding excellent agreement with published data on motor behavior. Analysis of the simulated switching dynamics revealed a mechanism for chemotactic ultrasensitivity, in which cooperativity is indispensable for realizing both coherent switching and effective amplification. These results showed how cells can combine elements of analog and digital control to produce switches that are simultaneously sensitive and reliable. PMID:22654654

Biotemplated flagellar nanoswimmers

NASA Astrophysics Data System (ADS)

Ali, Jamel; Cheang, U. Kei; Darvish, Armin; Kim, Hoyeon; Kim, Min Jun

2017-11-01

In this article, a porous hollow biotemplated nanoscale helix that can serve as a low Reynolds number robotic swimmer is reported. The nanorobot utilizes repolymerized bacterial flagella from Salmonella typhimurium as a nanotemplate for biomineralization. We demonstrate the ability to generate templated nanotubes with distinct helical geometries by using specific alkaline pH values to fix the polymorphic form of flagellar templates. Using uniform rotating magnetic fields to mimic the motion of the flagellar motor, we explore the swimming characteristics of these silica templated flagella and demonstrate the ability to wirelessly control their trajectories. The results suggest that the biotemplated nanoswimmer can be a cost-effective alternative to the current top-down methods used to produce helical nanorobots.

The flagellar motor of Caulobacter crescentus generates more torque when a cell swims backward

PubMed Central

Lele, Pushkar P.; Roland, Thibault; Shrivastava, Abhishek; Chen, Yihao; Berg, Howard C.

2016-01-01

Caulobacter crescentus, a monotrichous bacterium, swims by rotating a single right-handed helical filament. CW motor rotation thrusts the cell forward 1, a mode of motility known as the pusher mode; CCW motor rotation pulls the cell backward, a mode of motility referred to as the puller mode 2. The situation is opposite in E. coli, a peritrichous bacterium, where CCW rotation of multiple left-handed filaments drives the cell forward. The flagellar motor in E. coli generates more torque in the CCW direction than the CW direction in swimming cells 3,4. However, monotrichous bacteria including C. crescentus swim forward and backward at similar speeds, prompting the assumption that motor torques in the two modes are the same 5,6. Here, we present evidence that motors in C. crescentus develop higher torques in the puller mode than in the pusher mode, and suggest that the anisotropy in torque-generation is similar in two species, despite the differences in filament handedness and motor bias (probability of CW rotation). PMID:27499800

Second-chance signal transduction explains cooperative flagellar switching.

PubMed

Zot, Henry G; Hasbun, Javier E; Minh, Nguyen Van

2012-01-01

The reversal of flagellar motion (switching) results from the interaction between a switch complex of the flagellar rotor and a torque-generating stationary unit, or stator (motor unit). To explain the steeply cooperative ligand-induced switching, present models propose allosteric interactions between subunits of the rotor, but do not address the possibility of a reaction that stimulates a bidirectional motor unit to reverse direction of torque. During flagellar motion, the binding of a ligand-bound switch complex at the dwell site could excite a motor unit. The probability that another switch complex of the rotor, moving according to steady-state rotation, will reach the same dwell site before that motor unit returns to ground state will be determined by the independent decay rate of the excited-state motor unit. Here, we derive an analytical expression for the energy coupling between a switch complex and a motor unit of the stator complex of a flagellum, and demonstrate that this model accounts for the cooperative switching response without the need for allosteric interactions. The analytical result can be reproduced by simulation when (1) the motion of the rotor delivers a subsequent ligand-bound switch to the excited motor unit, thereby providing the excited motor unit with a second chance to remain excited, and (2) the outputs from multiple independent motor units are constrained to a single all-or-none event. In this proposed model, a motor unit and switch complex represent the components of a mathematically defined signal transduction mechanism in which energy coupling is driven by steady-state and is regulated by stochastic ligand binding. Mathematical derivation of the model shows the analytical function to be a general form of the Hill equation (Hill AV (1910) The possible effects of the aggregation of the molecules of haemoglobin on its dissociation curves. J Physiol 40: iv-vii).

Simultaneous measurement of bacterial flagellar rotation rate and swimming speed.

PubMed Central

Magariyama, Y; Sugiyama, S; Muramoto, K; Kawagishi, I; Imae, Y; Kudo, S

1995-01-01

Swimming speeds and flagellar rotation rates of individual free-swimming Vibrio alginolyticus cells were measured simultaneously by laser dark-field microscopy at 25, 30, and 35 degrees C. A roughly linear relation between swimming speed and flagellar rotation rate was observed. The ratio of swimming speed to flagellar rotation rate was 0.113 microns, which indicated that a cell progressed by 7% of pitch of flagellar helix during one flagellar rotation. At each temperature, however, swimming speed had a tendency to saturate at high flagellar rotation rate. That is, the cell with a faster-rotating flagellum did not always swim faster. To analyze the bacterial motion, we proposed a model in which the torque characteristics of the flagellar motor were considered. The model could be analytically solved, and it qualitatively explained the experimental results. The discrepancy between the experimental and the calculated ratios of swimming speed to flagellar rotation rate was about 20%. The apparent saturation in swimming speed was considered to be caused by shorter flagella that rotated faster but produced less propelling force. Images FIGURE 1 FIGURE 4 PMID:8580359

Sodium-driven energy conversion for flagellar rotation of the earliest divergent hyperthermophilic bacterium.

PubMed

Takekawa, Norihiro; Nishiyama, Masayoshi; Kaneseki, Tsuyoshi; Kanai, Tamotsu; Atomi, Haruyuki; Kojima, Seiji; Homma, Michio

2015-08-05

Aquifex aeolicus is a hyperthermophilic, hydrogen-oxidizing and carbon-fixing bacterium that can grow at temperatures up to 95 °C. A. aeolicus has an almost complete set of flagellar genes that are conserved in bacteria. Here we observed that A. aeolicus has polar flagellum and can swim with a speed of 90 μm s(-1) at 85 °C. We expressed the A. aeolicus mot genes (motA and motB), which encode the torque generating stator proteins of the flagellar motor, in a corresponding mot nonmotile mutant of Escherichia coli. Its motility was slightly recovered by expression of A. aeolicus MotA and chimeric MotB whose periplasmic region was replaced with that of E. coli. A point mutation in the A. aeolicus MotA cytoplasmic region remarkably enhanced the motility. Using this system in E. coli, we demonstrate that the A. aeolicus motor is driven by Na(+). As motor proteins from hyperthermophilic bacteria represent the earliest motor proteins in evolution, this study strongly suggests that ancient bacteria used Na(+) for energy coupling of the flagellar motor. The Na(+)-driven flagellar genes might have been laterally transferred from early-branched bacteria into late-branched bacteria and the interaction surfaces of the stator and rotor seem not to change in evolution.

Interactions of the chemotaxis signal protein CheY with bacterial flagellar motors visualized by evanescent wave microscopy.

PubMed

Khan, S; Pierce, D; Vale, R D

The chemotaxis signal protein CheY of enteric bacteria shuttles between transmembrane methyl-accepting chemotaxis protein (MCP) receptor complexes and flagellar basal bodies [1]. The basal body C-rings, composed of the FliM, FliG and FliN proteins, form the rotor of the flagellar motor [2]. Phosphorylated CheY binds to isolated FliM [3] and may also interact with FliG [4], but its binding to basal bodies has not been measured. Using the chemorepellent acetate to phosphorylate and acetylate CheY [5], we have measured the covalent-modification-dependent binding of a green fluorescent protein-CheY fusion (GFP-CheY) to motor assemblies in bacteria lacking MCP complexes by evanescent wave microscopy [6]. At acetate concentrations that cause solely clockwise rotation, GFP-CheY molecules bound to native basal bodies or to overproduced rotor complexes with a stoichiometry comparable to the number of C-ring subunits. GFP-CheY did not bind to rotors lacking FIiM/FliN, showing that these subunits are essential for the association. This assay provides a new means of monitoring protein-protein interactions in signal transduction pathways in living cells.

Arsenate arrests flagellar rotation in cytoplasm-free envelopes of bacteria.

PubMed Central

Margolin, Y; Barak, R; Eisenbach, M

1994-01-01

The effect of arsenate on flagellar rotation in cytoplasm-free flagellated envelopes of Escherichia coli and Salmonella typhimurium was investigated. Flagellar rotation ceased as soon as the envelopes were exposed to arsenate. Inclusion of phosphate intracellularly (but not extracellular) prevented the inhibition by arsenate. In a parallel experiment, the rotation was not affected by inclusion of an ATP trap (hexokinase and glucose) within the envelopes. It is concluded that arsenate affects the motor in a way other than reversible deenergization. This may be an irreversible damage to the cell or direct inhibition of the motor by arsenate. The latter possibility suggests that a process of phosphorylation or phosphate binding is involved in the motor function. PMID:8071237

Function of Proline Residues of MotA in Torque Generation by the Flagellar Motor of Escherichia coli

PubMed Central

Braun, Timothy F.; Poulson, Susan; Gully, Jonathan B.; Empey, J. Courtney; Van Way, Susan; Putnam, Angélica; Blair, David F.

1999-01-01

Bacterial flagellar motors obtain energy for rotation from the membrane gradient of protons or, in some species, sodium ions. The molecular mechanism of flagellar rotation is not understood. MotA and MotB are integral membrane proteins that function in proton conduction and are believed to form the stator of the motor. Previous mutational studies identified two conserved proline residues in MotA (Pro 173 and Pro 222 in the protein from Escherichia coli) and a conserved aspartic acid residue in MotB (Asp 32) that are important for function. Asp 32 of MotB probably forms part of the proton path through the motor. To learn more about the roles of the conserved proline residues of MotA, we examined motor function in Pro 173 and Pro 222 mutants, making measurements of torque at high load, speed at low and intermediate loads, and solvent-isotope effects (D2O versus H2O). Proton conduction by wild-type and mutant MotA-MotB channels was also assayed, by a growth defect that occurs upon overexpression. Several different mutations of Pro 173 reduced the torque of the motor under high load, and a few prevented motor rotation but still allowed proton flow through the MotA-MotB channels. These and other properties of the mutants suggest that Pro 173 has a pivotal role in coupling proton flow to motor rotation and is positioned in the channel near Asp 32 of MotB. Replacements of Pro 222 abolished function in all assays and were strongly dominant. Certain Pro 222 mutant proteins prevented swimming almost completely when expressed at moderate levels in wild-type cells. This dominance might be caused by rotor-stator jamming, because it was weaker when FliG carried a mutation believed to increase rotor-stator clearance. We propose a mechanism for torque generation, in which specific functions are suggested for the proline residues of MotA and Asp32 of MotB. PMID:10348868

Asymmetry in the clockwise and counterclockwise rotation of the bacterial flagellar motor

PubMed Central

Yuan, Junhua; Fahrner, Karen A.; Turner, Linda; Berg, Howard C.

2010-01-01

Cells of Escherichia coli are able to swim up gradients of chemical attractants by modulating the direction of rotation of their flagellar motors, which spin alternately clockwise (CW) and counterclockwise (CCW). Rotation in either direction has been thought to be symmetric and exhibit the same torques and speeds. The relationship between torque and speed is one of the most important measurable characteristics of the motor, used to distinguish specific mechanisms of motor rotation. Previous measurements of the torque–speed relationship have been made with cells lacking the response regulator CheY that spin their motors exclusively CCW. In this case, the torque declines slightly up to an intermediate speed called the “knee speed” after which it falls rapidly to zero. This result is consistent with a “power-stroke” mechanism for torque generation. Here, we measure the torque–speed relationship for cells that express large amounts of CheY and only spin their motors CW. We find that the torque decreases linearly with speed, a result remarkably different from that for CCW rotation. We obtain similar results for wild-type cells by reexamining data collected in previous work. We speculate that CCW rotation might be optimized for runs, with higher speeds increasing the ability of cells to sense spatial gradients, whereas CW rotation might be optimized for tumbles, where the object is to change cell trajectories. But why a linear torque–speed relationship might be optimum for the latter purpose we do not know. PMID:20615986

Proteomic Analysis of Intact Flagella of Procyclic Trypanosoma brucei Cells Identifies Novel Flagellar Proteins with Unique Sub-localization and Dynamics*

PubMed Central

Subota, Ines; Julkowska, Daria; Vincensini, Laetitia; Reeg, Nele; Buisson, Johanna; Blisnick, Thierry; Huet, Diego; Perrot, Sylvie; Santi-Rocca, Julien; Duchateau, Magalie; Hourdel, Véronique; Rousselle, Jean-Claude; Cayet, Nadège; Namane, Abdelkader; Chamot-Rooke, Julia; Bastin, Philippe

2014-01-01

Cilia and flagella are complex organelles made of hundreds of proteins of highly variable structures and functions. Here we report the purification of intact flagella from the procyclic stage of Trypanosoma brucei using mechanical shearing. Structural preservation was confirmed by transmission electron microscopy that showed that flagella still contained typical elements such as the membrane, the axoneme, the paraflagellar rod, and the intraflagellar transport particles. It also revealed that flagella severed below the basal body, and were not contaminated by other cytoskeletal structures such as the flagellar pocket collar or the adhesion zone filament. Mass spectrometry analysis identified a total of 751 proteins with high confidence, including 88% of known flagellar components. Comparison with the cell debris fraction revealed that more than half of the flagellum markers were enriched in flagella and this enrichment criterion was taken into account to identify 212 proteins not previously reported to be associated to flagella. Nine of these were experimentally validated including a 14-3-3 protein not yet reported to be associated to flagella and eight novel proteins termed FLAM (FLAgellar Member). Remarkably, they localized to five different subdomains of the flagellum. For example, FLAM6 is restricted to the proximal half of the axoneme, no matter its length. In contrast, FLAM8 is progressively accumulating at the distal tip of growing flagella and half of it still needs to be added after cell division. A combination of RNA interference and Fluorescence Recovery After Photobleaching approaches demonstrated very different dynamics from one protein to the other, but also according to the stage of construction and the age of the flagellum. Structural proteins are added to the distal tip of the elongating flagellum and exhibit slow turnover whereas membrane proteins such as the arginine kinase show rapid turnover without a detectible polarity. PMID:24741115

Temperature Dependences of Torque Generation and Membrane Voltage in the Bacterial Flagellar Motor

PubMed Central

Inoue, Yuichi; Baker, Matthew A.B.; Fukuoka, Hajime; Takahashi, Hiroto; Berry, Richard M.; Ishijima, Akihiko

2013-01-01

In their natural habitats bacteria are frequently exposed to sudden changes in temperature that have been shown to affect their swimming. With our believed to be new methods of rapid temperature control for single-molecule microscopy, we measured here the thermal response of the Na+-driven chimeric motor expressed in Escherichia coli cells. Motor torque at low load (0.35 μm bead) increased linearly with temperature, twofold between 15°C and 40°C, and torque at high load (1.0 μm bead) was independent of temperature, as reported for the H+-driven motor. Single cell membrane voltages were measured by fluorescence imaging and these were almost constant (∼120 mV) over the same temperature range. When the motor was heated above 40°C for 1–2 min the torque at high load dropped reversibly, recovering upon cooling below 40°C. This response was repeatable over as many as 10 heating cycles. Both increases and decreases in torque showed stepwise torque changes with unitary size ∼150 pN nm, close to the torque of a single stator at room temperature (∼180 pN nm), indicating that dynamic stator dissociation occurs at high temperature, with rebinding upon cooling. Our results suggest that the temperature-dependent assembly of stators is a general feature of flagellar motors. PMID:24359752

Speed of the bacterial flagellar motor near zero load depends on the number of stator units.

PubMed

Nord, Ashley L; Sowa, Yoshiyuki; Steel, Bradley C; Lo, Chien-Jung; Berry, Richard M

2017-10-31

The bacterial flagellar motor (BFM) rotates hundreds of times per second to propel bacteria driven by an electrochemical ion gradient. The motor consists of a rotor 50 nm in diameter surrounded by up to 11 ion-conducting stator units, which exchange between motors and a membrane-bound pool. Measurements of the torque-speed relationship guide the development of models of the motor mechanism. In contrast to previous reports that speed near zero torque is independent of the number of stator units, we observe multiple speeds that we attribute to different numbers of units near zero torque in both Na + - and H + -driven motors. We measure the full torque-speed relationship of one and two H + units in Escherichia coli by selecting the number of H + units and controlling the number of Na + units in hybrid motors. These experiments confirm that speed near zero torque in H + -driven motors increases with the stator number. We also measured 75 torque-speed curves for Na + -driven chimeric motors at different ion-motive force and stator number. Torque and speed were proportional to ion-motive force and number of stator units at all loads, allowing all 77 measured torque-speed curves to be collapsed onto a single curve by simple rescaling. Published under the PNAS license.

Speed of the bacterial flagellar motor near zero load depends on the number of stator units

PubMed Central

Nord, Ashley L.; Sowa, Yoshiyuki; Steel, Bradley C.; Lo, Chien-Jung; Berry, Richard M.

2017-01-01

The bacterial flagellar motor (BFM) rotates hundreds of times per second to propel bacteria driven by an electrochemical ion gradient. The motor consists of a rotor 50 nm in diameter surrounded by up to 11 ion-conducting stator units, which exchange between motors and a membrane-bound pool. Measurements of the torque–speed relationship guide the development of models of the motor mechanism. In contrast to previous reports that speed near zero torque is independent of the number of stator units, we observe multiple speeds that we attribute to different numbers of units near zero torque in both Na+- and H+-driven motors. We measure the full torque–speed relationship of one and two H+ units in Escherichia coli by selecting the number of H+ units and controlling the number of Na+ units in hybrid motors. These experiments confirm that speed near zero torque in H+-driven motors increases with the stator number. We also measured 75 torque–speed curves for Na+-driven chimeric motors at different ion-motive force and stator number. Torque and speed were proportional to ion-motive force and number of stator units at all loads, allowing all 77 measured torque–speed curves to be collapsed onto a single curve by simple rescaling. PMID:29078322

Motility and Flagellar Glycosylation in Clostridium difficile▿ †

PubMed Central

Twine, Susan M.; Reid, Christopher W.; Aubry, Annie; McMullin, David R.; Fulton, Kelly M.; Austin, John; Logan, Susan M.

2009-01-01

In this study, intact flagellin proteins were purified from strains of Clostridium difficile and analyzed using quadrupole time of flight and linear ion trap mass spectrometers. Top-down studies showed the flagellin proteins to have a mass greater than that predicted from the corresponding gene sequence. These top-down studies revealed marker ions characteristic of glycan modifications. Additionally, diversity in the observed masses of glycan modifications was seen between strains. Electron transfer dissociation mass spectrometry was used to demonstrate that the glycan was attached to the flagellin protein backbone in O linkage via a HexNAc residue in all strains examined. Bioinformatic analysis of C. difficile genomes revealed diversity with respect to glycan biosynthesis gene content within the flagellar biosynthesis locus, likely reflected by the observed flagellar glycan diversity. In C. difficile strain 630, insertional inactivation of a glycosyltransferase gene (CD0240) present in all sequenced genomes resulted in an inability to produce flagellar filaments at the cell surface and only minor amounts of unmodified flagellin protein. PMID:19749038

H{sup +} and Na{sup +} are involved in flagellar rotation of the spirochete Leptospira

DOE Office of Scientific and Technical Information (OSTI.GOV)

Islam, Md. Shafiqul; Morimoto, Yusuke V.; Graduate School of Frontier BioSciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871

2015-10-16

Leptospira is a spirochete possessing intracellular flagella. Each Leptospira flagellar filament is linked with a flagellar motor composed of a rotor and a dozen stators. For many bacterial species, it is known that the stator functions as an ion channel and that the ion flux through the stator is coupled with flagellar rotation. The coupling ion varies depending on the species; for example, H{sup +} is used in Escherichia coli, and Na{sup +} is used in Vibrio spp. to drive a polar flagellum. Although genetic and structural studies illustrated that the Leptospira flagellar motor also contains a stator, the couplingmore » ion for flagellar rotation remains unknown. In the present study, we analyzed the motility of Leptospira under various pH values and salt concentrations. Leptospira cells displayed motility in acidic to alkaline pH. In the presence of a protonophore, the cells completely lost motility in acidic to neutral pH but displayed extremely slow movement under alkaline conditions. This result suggests that H{sup +} is a major coupling ion for flagellar rotation over a wide pH range; however, we also observed that the motility of Leptospira was significantly enhanced by the addition of Na{sup +}, though it vigorously moved even under Na{sup +}-free conditions. These results suggest that H{sup +} is preferentially used and that Na{sup +} is secondarily involved in flagellar rotation in Leptospira. The flexible ion selectivity in the flagellar system could be advantageous for Leptospira to survive in a wide range of environment. - Highlights: • This is a study on input energy for motility in the spirochete Leptospira. • Leptospira biflexa exhibited active motility in acidic to alkaline pH. • Both H{sup +} and Na{sup +} are involved in flagellar rotation in Leptospira. • H{sup +} is a primary energy source, but Na{sup +} can secondarily enhance motility.« less

Load- and polysaccharide-dependent activation of the Na+-type MotPS stator in the Bacillus subtilis flagellar motor.

PubMed

Terahara, Naoya; Noguchi, Yukina; Nakamura, Shuichi; Kami-Ike, Nobunori; Ito, Masahiro; Namba, Keiichi; Minamino, Tohru

2017-04-05

The flagellar motor of Bacillus subtilis possesses two distinct H + -type MotAB and Na + -type MotPS stators. In contrast to the MotAB motor, the MotPS motor functions efficiently at elevated viscosity in the presence of 200 mM NaCl. Here, we analyzed the torque-speed relationship of the Bacillus MotAB and MotPS motors over a wide range of external loads. The stall torque of the MotAB and MotPS motors at high load was about 2,200 pN nm and 220 pN nm, respectively. The number of active stators in the MotAB and MotPS motors was estimated to be about ten and one, respectively. However, the number of functional stators in the MotPS motor was increased up to ten with an increase in the concentration of a polysaccharide, Ficoll 400, as well as in the load. The maximum speeds of the MotAB and MotPS motors at low load were about 200 Hz and 50 Hz, respectively, indicating that the rate of the torque-generation cycle of the MotPS motor is 4-fold slower than that of the MotAB motor. Domain exchange experiments showed that the C-terminal periplasmic domain of MotS directly controls the assembly and disassembly dynamics of the MotPS stator in a load- and polysaccharide-dependent manner.

Load- and polysaccharide-dependent activation of the Na+-type MotPS stator in the Bacillus subtilis flagellar motor

PubMed Central

Terahara, Naoya; Noguchi, Yukina; Nakamura, Shuichi; Kami-ike, Nobunori; Ito, Masahiro; Namba, Keiichi; Minamino, Tohru

2017-01-01

The flagellar motor of Bacillus subtilis possesses two distinct H+-type MotAB and Na+-type MotPS stators. In contrast to the MotAB motor, the MotPS motor functions efficiently at elevated viscosity in the presence of 200 mM NaCl. Here, we analyzed the torque-speed relationship of the Bacillus MotAB and MotPS motors over a wide range of external loads. The stall torque of the MotAB and MotPS motors at high load was about 2,200 pN nm and 220 pN nm, respectively. The number of active stators in the MotAB and MotPS motors was estimated to be about ten and one, respectively. However, the number of functional stators in the MotPS motor was increased up to ten with an increase in the concentration of a polysaccharide, Ficoll 400, as well as in the load. The maximum speeds of the MotAB and MotPS motors at low load were about 200 Hz and 50 Hz, respectively, indicating that the rate of the torque-generation cycle of the MotPS motor is 4-fold slower than that of the MotAB motor. Domain exchange experiments showed that the C-terminal periplasmic domain of MotS directly controls the assembly and disassembly dynamics of the MotPS stator in a load- and polysaccharide-dependent manner. PMID:28378843

Bacterial flagellar microhydrodynamics: Laminar flow over complex flagellar filaments, analog archimedean screws and cylinders, and its perturbations.

PubMed

Trachtenberg, Shlomo; Fishelov, Dalia; Ben-Artzi, Matania

2003-09-01

The flagellar filament, the bacterial organelle of motility, is the smallest rotary propeller known. It consists of 1), a basal body (part of which is the proton driven rotary motor), 2), a hook (universal joint-allowing for off-axial transmission of rotary motion), and 3), a filament (propeller-a long, rigid, supercoiled helical assembly allowing for the conversion of rotary motion into linear thrust). Helically perturbed (so-called "complex") filaments have a coarse surface composed of deep grooves and ridges following the three-start helical lines. These surface structures, reminiscent of a turbine or Archimedean screw, originate from symmetry reduction along the six-start helical lines due to dimerization of the flagellin monomers from which the filament self assembles. Using high-resolution electron microscopy and helical image reconstruction methods, we calculated three-dimensional density maps of the complex filament of Rhizobium lupini H13-3 and determined its surface pattern and boundaries. The helical symmetry of the filament allows viewing it as a stack of identical slices spaced axially and rotated by constant increments. Here we use the closed outlines of these slices to explore, in two dimensions, the hydrodynamic effect of the turbine-like boundaries of the flagellar filament. In particular, we try to determine if, and under what conditions, transitions from laminar to turbulent flow (or perturbations of the laminar flow) may occur on or near the surface of the bacterial propeller. To address these questions, we apply the boundary element method in a manner allowing the handling of convoluted boundaries. We tested the method on several simple, well-characterized cylindrical structures before applying it to real, highly convoluted biological surfaces and to simplified mechanical analogs. Our results indicate that under extreme structural and functional conditions, and at low Reynolds numbers, a deviation from laminar flow might occur on the flagellar

Instability of hooks during bacterial flagellar swimming

NASA Astrophysics Data System (ADS)

Jabbarzadeh, Mehdi; Fu, Henry C.; Henry Fu Team

2016-11-01

In bacteria, a flexible hook transmits torque from the rotary motor at the cell body to the flagellum. Previously, the hook has been modeled as a Kirchhoff rod between the cell body and rotating flagellum. To study effects of the hook's flexibility on the bacteria's swimming speed and trajectory for wide range hook stiffnesses and flagellum configurations, we develop an efficient simplified spring model for the hook by linearizing the Kirchhoff rod. We treat the hydrodynamics of the cell body and helical flagellum using resistance matrices calculated by the method of regularized Stokeslets. We investigate flagellar and swimming dynamics for a range of hook flexibilities and flagellar orientations relative to the cell body and compare the results to models without hook flexibility. We investigate in detail parameters corresponding to E. coli and Vibrio alginolyticus. Generally, the flagellum changes orientation relative to the cell body, undergoing an orbit with the period of the motor rotation. We find that as the hook stiffness decreases, steady-state orbits of the flagellum first become unstable before the hook buckles, which may suggest a new mechanism of flick initiation in run-reverse-flick motility. We also find that for some parameter ranges, there are multiple stable steady state orbits, which may have implications for the tumbling and turning of bacteria.

Flagellar Synchronization Is a Simple Alternative to Cell Cycle Synchronization for Ciliary and Flagellar Studies

PubMed Central

Dutta, Soumita

2017-01-01

ABSTRACT 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. This results in a maximally homogeneous distribution of flagellar lengths at 3 h postamputation. We found that time-limiting new protein synthesis during flagellar synchronization limits variability in the unassembled pool of limiting flagellar protein and variability in flagellar length without affecting the range of cell volumes. We also found that long- and short-flagella mutants that regenerate normally require longer and shorter synchronization times, respectively. By minimizing flagellar length variability using a simple method requiring only hours and no changes in media, flagellar synchronization facilitates the detection of small changes in flagellar length resulting from both chemical and genetic perturbations in Chlamydomonas. This method increases our ability to probe the basic biology of ciliary size regulation and related disease etiologies. IMPORTANCE Cilia and flagella are highly conserved antenna-like organelles that found in nearly all mammalian cell types. They perform sensory and motile functions contributing to numerous physiological and developmental processes. Defects in their assembly and function are implicated in a wide range of human diseases ranging from retinal degeneration to cancer. Chlamydomonas reinhardtii is an algal model system for studying mammalian cilium formation and function. Here, we report a simple synchronization method that allows detection of

Flagellar Synchronization Is a Simple Alternative to Cell Cycle Synchronization for Ciliary and Flagellar Studies.

PubMed

Dutta, Soumita; Avasthi, Prachee

2017-01-01

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. This results in a maximally homogeneous distribution of flagellar lengths at 3 h postamputation. We found that time-limiting new protein synthesis during flagellar synchronization limits variability in the unassembled pool of limiting flagellar protein and variability in flagellar length without affecting the range of cell volumes. We also found that long- and short-flagella mutants that regenerate normally require longer and shorter synchronization times, respectively. By minimizing flagellar length variability using a simple method requiring only hours and no changes in media, flagellar synchronization facilitates the detection of small changes in flagellar length resulting from both chemical and genetic perturbations in Chlamydomonas . This method increases our ability to probe the basic biology of ciliary size regulation and related disease etiologies. IMPORTANCE Cilia and flagella are highly conserved antenna-like organelles that found in nearly all mammalian cell types. They perform sensory and motile functions contributing to numerous physiological and developmental processes. Defects in their assembly and function are implicated in a wide range of human diseases ranging from retinal degeneration to cancer. Chlamydomonas reinhardtii is an algal model system for studying mammalian cilium formation and function. Here, we report a simple synchronization method that allows detection of small

Kinematics of flagellar swimming in Euglena gracilis: Helical trajectories and flagellar shapes.

PubMed

Rossi, Massimiliano; Cicconofri, Giancarlo; Beran, Alfred; Noselli, Giovanni; DeSimone, Antonio

2017-12-12

The flagellar swimming of euglenids, which are propelled by a single anterior flagellum, is characterized by a generalized helical motion. The 3D nature of this swimming motion, which lacks some of the symmetries enjoyed by more common model systems, and the complex flagellar beating shapes that power it make its quantitative description challenging. In this work, we provide a quantitative, 3D, highly resolved reconstruction of the swimming trajectories and flagellar shapes of specimens of Euglena gracilis We achieved this task by using high-speed 2D image recordings taken with a conventional inverted microscope combined with a precise characterization of the helical motion of the cell body to lift the 2D data to 3D trajectories. The propulsion mechanism is discussed. Our results constitute a basis for future biophysical research on a relatively unexplored type of eukaryotic flagellar movement. Copyright © 2017 the Author(s). Published by PNAS.

Flagellar glycosylation in Clostridium botulinum.

PubMed

Twine, Susan M; Paul, Catherine J; Vinogradov, Evgeny; McNally, David J; Brisson, Jean-Robert; Mullen, James A; McMullin, David R; Jarrell, Harold C; Austin, John W; Kelly, John F; Logan, Susan M

2008-09-01

Flagellins from Clostridium botulinum were shown to be post-translationally modified with novel glycan moieties by top-down MS analysis of purified flagellin protein from strains of various toxin serotypes. Detailed analyses of flagellin from two strains of C. botulinum demonstrated that the protein is modified by a novel glycan moiety of mass 417 Da in O-linkage. Bioinformatic analysis of available C. botulinum genomes identified a flagellar glycosylation island containing homologs of genes recently identified in Campylobacter coli that have been shown to be responsible for the biosynthesis of legionaminic acid derivatives. Structural characterization of the carbohydrate moiety was completed utilizing both MS and NMR spectroscopy, and it was shown to be a novel legionaminic acid derivative, 7-acetamido-5-(N-methyl-glutam-4-yl)-amino-3,5,7,9-tetradeoxy-D-glycero-alpha-D-galacto-nonulosonic acid, (alphaLeg5GluNMe7Ac). Electron transfer dissociation MS with and without collision-activated dissociation was utilized to map seven sites of O-linked glycosylation, eliminating the need for chemical derivatization of tryptic peptides prior to analysis. Marker ions for novel glycans, as well as a unique C-terminal flagellin peptide marker ion, were identified in a top-down analysis of the intact protein. These ions have the potential for use in for rapid detection and discrimination of C. botulinum cells, indicating botulinum neurotoxin contamination. This is the first report of glycosylation of Gram-positive flagellar proteins by the 'sialic acid-like' nonulosonate sugar, legionaminic acid.

Gap compression/extension mechanism of bacterial flagellar hook as the molecular universal joint.

PubMed

Furuta, Tadaomi; Samatey, Fadel A; Matsunami, Hideyuki; Imada, Katsumi; Namba, Keiichi; Kitao, Akio

2007-03-01

Bacterial flagellar hook acts as a molecular universal joint, transmitting torque produced by the flagellar basal body, a rotary motor, to the flagellar filament. The hook forms polymorphic supercoil structures and can be considered as an assembly of 11 circularly arranged protofilaments. We investigated the molecular mechanism of the universal joint function of the hook by a approximately two-million-atom molecular dynamics simulation. On the inner side of the supercoil, protein subunits are highly packed along the protofilament and no gaps remain for further compression, whereas subunits are slightly separated and are hydrogen bonded through one layer of water molecules on the outer side. As for the intersubunit interactions between protofilaments, subunits are packed along the 6-start helix in a left-handed supercoil whereas they are highly packed along the 5-start helix in a right-handed supercoil. We conclude that the supercoiled structures of the hook in the left- and right-handed forms make maximal use of the gaps between subunits, which we call "gap compression/extension mechanism". Mutual sliding of subunits at the subunit interface accompanying rearrangements of intersubunit hydrogen bonds is interpreted as a mechanism to allow continuous structural change of the hook during flagellar rotation at low energy cost.

Structure of the bacterial flagellar hook and implication for the molecular universal joint mechanism.

PubMed

Samatey, Fadel A; Matsunami, Hideyuki; Imada, Katsumi; Nagashima, Shigehiro; Shaikh, Tanvir R; Thomas, Dennis R; Chen, James Z; Derosier, David J; Kitao, Akio; Namba, Keiichi

2004-10-28

The bacterial flagellum is a motile organelle, and the flagellar hook is a short, highly curved tubular structure that connects the flagellar motor to the long filament acting as a helical propeller. The hook is made of about 120 copies of a single protein, FlgE, and its function as a nano-sized universal joint is essential for dynamic and efficient bacterial motility and taxis. It transmits the motor torque to the helical propeller over a wide range of its orientation for swimming and tumbling. Here we report a partial atomic model of the hook obtained by X-ray crystallography of FlgE31, a major proteolytic fragment of FlgE lacking unfolded terminal regions, and by electron cryomicroscopy and three-dimensional helical image reconstruction of the hook. The model reveals the intricate molecular interactions and a plausible switching mechanism for the hook to be flexible in bending but rigid against twisting for its universal joint function.

Computing the motor torque of Escherichia coli.

PubMed

Das, Debasish; Lauga, Eric

2018-06-13

The rotary motor of bacteria is a natural nano-technological marvel that enables cell locomotion by powering the rotation of semi-rigid helical flagellar filaments in fluid environments. It is well known that the motor operates essentially at constant torque in counter-clockwise direction but past work have reported a large range of values of this torque. Focusing on Escherichia coli cells that are swimming and cells that are stuck on a glass surface for which all geometrical and environmental parameters are known (N. C. Darnton et al., J. Bacteriol., 2007, 189, 1756-1764), we use two validated numerical methods to compute the value of the motor torque consistent with experiments. Specifically, we use (and compare) a numerical method based on the boundary integral representation of Stokes flow and also develop a hybrid method combining boundary element and slender body theory to model the cell body and flagellar filament, respectively. Using measured rotation speed of the motor, our computations predict a value of the motor torque in the range 440 pN nm to 829 pN nm, depending critically on the distance between the flagellar filaments and the nearby surface.

Bacteria exploit a polymorphic instability of the flagellar filament to escape from traps.

PubMed

Kühn, Marco J; Schmidt, Felix K; Eckhardt, Bruno; Thormann, Kai M

2017-06-13

Many bacterial species swim by rotating single polar helical flagella. Depending on the direction of rotation, they can swim forward or backward and change directions to move along chemical gradients but also to navigate their obstructed natural environment in soils, sediments, or mucus. When they get stuck, they naturally try to back out, but they can also resort to a radically different flagellar mode, which we discovered here. Using high-speed microscopy, we monitored the swimming behavior of the monopolarly flagellated species Shewanella putrefaciens with fluorescently labeled flagellar filaments at an agarose-glass interface. We show that, when a cell gets stuck, the polar flagellar filament executes a polymorphic change into a spiral-like form that wraps around the cell body in a spiral-like fashion and enables the cell to escape by a screw-like backward motion. Microscopy and modeling suggest that this propagation mode is triggered by an instability of the flagellum under reversal of the rotation and the applied torque. The switch is reversible and bacteria that have escaped the trap can return to their normal swimming mode by another reversal of motor direction. The screw-type flagellar arrangement enables a unique mode of propagation and, given the large number of polarly flagellated bacteria, we expect it to be a common and widespread escape or motility mode in complex and structured environments.

Flagellar dynamics reveal the distribution of chemotactic signaling molecule CheY-P in E. coli

NASA Astrophysics Data System (ADS)

Bano, Roshni; Mears, Patrick; Chemla, Yann; Golding, Ido

E. colicells swim in a random walk consisting of ''runs'' - during which the flagella that propel the cell rotate counter-clockwise (CCW) - and ''tumbles''- during which one or more flagella rotate clockwise (CW). The tumbling frequency is modulated by the phosphorylation state of the signaling molecule CheY, which depends on the cell's environment. Phosphorylated CheY (CheY-P) binds to a flagellar motor and engenders a change in rotation state from CCW to CW. Despite advances in methods used to observe chemotactic signaling, it remains a challenge to measure the CheY-P level in cells directly. Here, we used an optical trap assay coupled with fluorescence microscopy to observe the dynamics of fluorescently labelled flagella in individual cells. By measuring the distribution of flagellar states in multi-flagellated cells and using our recent finding that each flagellar motor independently measures the cellular CheY-P concentration, we are able to extract the probability distribution of the CheY-P level in the cell. This analysis reveals the magnitude of fluctuations in chemotactic signaling in the live cell. We further investigate how this CheY-P distribution changes when cells encounter chemical gradients and perform chemotaxis. This work was supported by the National Science Foundation (NSF) through the Centre for Physics of Living Cells (CPLC).

Expression, purification and biochemical characterization of the cytoplasmic loop of PomA, a stator component of the Na+ driven flagellar motor

PubMed Central

Abe-Yoshizumi, Rei; Kobayashi, Shiori; Gohara, Mizuki; Hayashi, Kokoro; Kojima, Chojiro; Kojima, Seiji; Sudo, Yuki; Asami, Yasuo; Homma, Michio

2013-01-01

Flagellar motors embedded in bacterial membranes are molecular machines powered by specific ion flows. Each motor is composed of a stator and a rotor and the interactions of those components are believed to generate the torque. Na+ influx through the PomA/PomB stator complex of Vibrio alginolyticus is coupled to torque generation and is speculated to trigger structural changes in the cytoplasmic domain of PomA that interacts with a rotor protein in the C-ring, FliG, to drive the rotation. In this study, we tried to overproduce the cytoplasmic loop of PomA (PomA-Loop), but it was insoluble. Thus, we made a fusion protein with a small soluble tag (GB1) which allowed us to express and characterize the recombinant protein. The structure of the PomA-Loop seems to be very elongated or has a loose tertiary structure. When the PomA-Loop protein was produced in E. coli, a slight dominant effect was observed on motility. We conclude that the cytoplasmic loop alone retains a certain function. PMID:27493537

Noise effects in bacterial motor switch

NASA Astrophysics Data System (ADS)

Tu, Yuhai

2006-03-01

The clockwise (CW) or counter clockwise (CCW) spinning of bacterial flagellar motors is controlled by the concentration of a phosphorylated protein CheY-P. In this talk, we represent the stochastic switching behavior of a bacterial flagellar motor by a dynamical two-state (CW and CCW) model, with the energy levels of the two states fluctuating in time according to the variation of the CheY-P concentration in the cell. We show that with a generic normal distribution and a modest amplitude for CheY-P concentration fluctuations, the dynamical two-state model is capable of generating a power-law distribution (as opposed to an exponential Poisson-like distribution) for the durations of the CCW states, in agreement with recent experimental observations of Korobkova et al (Nature, 428, 574(2004)). In addition, we show that the power spectrum for the flagellar motor switching time series is not determined solely by the power-law duration distribution, but also by the temporal correlation between the duration times of different CCW intervals. We point out the intrinsic connection between anomalously large fluctuations of the motor output and the overall high gain of the bacterial chemotaxis system. Suggestions for experimental verification of the dynamical two-state model will also be discussed.

A solid-state control system for dynein-based ciliary/flagellar motility

PubMed Central

2013-01-01

Ciliary and flagellar beating requires the coordinated action of multiple dyneins with different enzymatic and motor properties. In this issue, Yamamoto et al. (2013. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201211048) identify the MIA (modifier of inner arms) complex within the Chlamydomonas reinhardtii axoneme that physically links to a known regulatory structure and provides a signaling conduit from the radial spokes to an inner arm dynein essential for waveform determination. PMID:23569213

The Flagellar Regulon of Legionella—A Review

PubMed Central

Appelt, Sandra; Heuner, Klaus

2017-01-01

The Legionella genus comprises more than 60 species. In particular, Legionella pneumophila is known to cause severe illnesses in humans. Legionellaceae are ubiquitous inhabitants of aquatic environments. Some Legionellaceae are motile and their motility is important to move around in habitats. Motility can be considered as a potential virulence factor as already shown for various human pathogens. The genes of the flagellar system, regulator and structural genes, are structured in hierarchical levels described as the flagellar regulon. Their expression is modulated by various environmental factors. For L. pneumophila it was shown that the expression of genes of the flagellar regulon is modulated by the actual growth phase and temperature. Especially, flagellated Legionella are known to express genes during the transmissive phase of growth that are involved in the expression of virulence traits. It has been demonstrated that the alternative sigma-28 factor is part of the link between virulence expression and motility. In the following review, the structure of the flagellar regulon of L. pneumophila is discussed and compared to other flagellar systems of different Legionella species. Recently, it has been described that Legionella micdadei and Legionella fallonii contain a second putative partial flagellar system. Hence, the report will focus on flagellated and non-flagellated Legionella strains, phylogenetic relationships, the role and function of the alternative sigma factor (FliA) and its anti-sigma-28 factor (FlgM). PMID:29104863

The Flagellar Regulon of Legionella-A Review.

PubMed

Appelt, Sandra; Heuner, Klaus

2017-01-01

The Legionella genus comprises more than 60 species. In particular, Legionella pneumophila is known to cause severe illnesses in humans. Legionellaceae are ubiquitous inhabitants of aquatic environments. Some Legionellaceae are motile and their motility is important to move around in habitats. Motility can be considered as a potential virulence factor as already shown for various human pathogens. The genes of the flagellar system, regulator and structural genes, are structured in hierarchical levels described as the flagellar regulon. Their expression is modulated by various environmental factors. For L. pneumophila it was shown that the expression of genes of the flagellar regulon is modulated by the actual growth phase and temperature. Especially, flagellated Legionella are known to express genes during the transmissive phase of growth that are involved in the expression of virulence traits. It has been demonstrated that the alternative sigma-28 factor is part of the link between virulence expression and motility. In the following review, the structure of the flagellar regulon of L. pneumophila is discussed and compared to other flagellar systems of different Legionella species. Recently, it has been described that Legionella micdadei and Legionella fallonii contain a second putative partial flagellar system. Hence, the report will focus on flagellated and non-flagellated Legionella strains, phylogenetic relationships, the role and function of the alternative sigma factor (FliA) and its anti-sigma-28 factor (FlgM).

Purification and Thermal Stability of Intact Bacillus subtilis Flagella

PubMed Central

Dimmitt, K.; Simon, M.

1971-01-01

Flagella were prepared and purified in a relatively intact form from bacterial lysates. Immunochemical tests showed that over 95% of the protein in the final preparation consisted of flagellar antigen. These flagella are more stable to thermal denaturation than flagella filaments obtained by shearing. Their thermal properties more closely resemble those of flagella in the native state on bacteria. The presence of the hook structure is responsible for this extra stability. Images PMID:4993323

The bacterial flagellar switch complex is getting more complex

PubMed Central

Cohen-Ben-Lulu, Galit N; Francis, Noreen R; Shimoni, Eyal; Noy, Dror; Davidov, Yaacov; Prasad, Krishna; Sagi, Yael; Cecchini, Gary; Johnstone, Rose M; Eisenbach, Michael

2008-01-01

The mechanism of function of the bacterial flagellar switch, which determines the direction of flagellar rotation and is essential for chemotaxis, has remained an enigma for many years. Here we show that the switch complex associates with the membrane-bound respiratory protein fumarate reductase (FRD). We provide evidence that FRD binds to preparations of isolated switch complexes, forms a 1:1 complex with the switch protein FliG, and that this interaction is required for both flagellar assembly and switching the direction of flagellar rotation. We further show that fumarate, known to be a clockwise/switch factor, affects the direction of flagellar rotation through FRD. These results not only uncover a new component important for switching and flagellar assembly, but they also reveal that FRD, an enzyme known to be primarily expressed and functional under anaerobic conditions in Escherichia coli, nonetheless, has important, unexpected functions under aerobic conditions. PMID:18337747

The C-terminal periplasmic domain of MotB is responsible for load-dependent control of the number of stators of the bacterial flagellar motor.

PubMed

Castillo, David J; Nakamura, Shuichi; Morimoto, Yusuke V; Che, Yong-Suk; Kami-Ike, Nobunori; Kudo, Seishi; Minamino, Tohru; Namba, Keiichi

2013-01-01

The bacterial flagellar motor is made of a rotor and stators. In Salmonella it is thought that about a dozen MotA/B complexes are anchored to the peptidoglycan layer around the motor through the C-terminal peptidoglycan-binding domain of MotB to become active stators as well as proton channels. MotB consists of 309 residues, forming a single transmembrane helix (30-50), a stalk (51-100) and a C-terminal peptidoglycan-binding domain (101-309). Although the stalk is dispensable for torque generation by the motor, it is required for efficient motor performance. Residues 51 to 72 prevent premature proton leakage through the proton channel prior to stator assembly into the motor. However, the role of residues 72-100 remains unknown. Here, we analyzed the torque-speed relationship of the MotB(Δ72-100) motor. At a low speed near stall, this mutant motor produced torque at the wild-type level. Unlike the wild-type motor, however, torque dropped off drastically by slight decrease in external load and then showed a slow exponential decay over a wide range of load by its further reduction. Since it is known that the stator is a mechano-sensor and that the number of active stators changes in a load-dependent manner, we interpreted this unusual torque-speed relationship as anomaly in load-dependent control of the number of active stators. The results suggest that residues 72-100 of MotB is required for proper load-dependent control of the number of active stators around the rotor.

Coevolved Mutations Reveal Distinct Architectures for Two Core Proteins in the Bacterial Flagellar Motor

PubMed Central

Pandini, Alessandro; Kleinjung, Jens; Rasool, Shafqat; Khan, Shahid

2015-01-01

Switching of bacterial flagellar rotation is caused by large domain movements of the FliG protein triggered by binding of the signal protein CheY to FliM. FliG and FliM form adjacent multi-subunit arrays within the basal body C-ring. The movements alter the interaction of the FliG C-terminal (FliGC) “torque” helix with the stator complexes. Atomic models based on the Salmonella entrovar C-ring electron microscopy reconstruction have implications for switching, but lack consensus on the relative locations of the FliG armadillo (ARM) domains (amino-terminal (FliGN), middle (FliGM) and FliGC) as well as changes during chemotaxis. The generality of the Salmonella model is challenged by the variation in motor morphology and response between species. We studied coevolved residue mutations to determine the unifying elements of switch architecture. Residue interactions, measured by their coevolution, were formalized as a network, guided by structural data. Our measurements reveal a common design with dedicated switch and motor modules. The FliM middle domain (FliMM) has extensive connectivity most simply explained by conserved intra and inter-subunit contacts. In contrast, FliG has patchy, complex architecture. Conserved structural motifs form interacting nodes in the coevolution network that wire FliMM to the FliGC C-terminal, four-helix motor module (C3-6). FliG C3-6 coevolution is organized around the torque helix, differently from other ARM domains. The nodes form separated, surface-proximal patches that are targeted by deleterious mutations as in other allosteric systems. The dominant node is formed by the EHPQ motif at the FliMMFliGM contact interface and adjacent helix residues at a central location within FliGM. The node interacts with nodes in the N-terminal FliGc α-helix triad (ARM-C) and FliGN. ARM-C, separated from C3-6 by the MFVF motif, has poor intra-network connectivity consistent with its variable orientation revealed by structural data. ARM-C could

Inactivation of ferric uptake regulator (Fur) attenuates Helicobacter pylori J99 motility by disturbing the flagellar motor switch and autoinducer-2 production.

PubMed

Lee, Ai-Yun; Kao, Cheng-Yen; Wang, Yao-Kuan; Lin, Ssu-Yuan; Lai, Tze-Ying; Sheu, Bor-Shyang; Lo, Chien-Jung; Wu, Jiunn-Jong

2017-08-01

Flagellar motility of Helicobacter pylori has been shown to be important for the bacteria to establish initial colonization. The ferric uptake regulator (Fur) is a global regulator that has been identified in H. pylori which is involved in the processes of iron uptake and establishing colonization. However, the role of Fur in H. pylori motility is still unclear. Motility of the wild-type, fur mutant, and fur revertant J99 were determined by a soft-agar motility assay and direct video observation. The bacterial shape and flagellar structure were evaluated by transmission electron microscopy. Single bacterial motility and flagellar switching were observed by phase-contrast microscopy. Autoinducer-2 (AI-2) production in bacterial culture supernatant was analyzed by a bioluminescence assay. The fur mutant showed impaired motility in the soft-agar assay compared with the wild-type J99 and fur revertant. The numbers and lengths of flagellar filaments on the fur mutant cells were similar to those of the wild-type and revertant cells. Phenotypic characterization showed similar swimming speed but reduction in switching rate in the fur mutant. The AI-2 production of the fur mutant was dramatically reduced compared with wild-type J99 in log-phase culture medium. These results indicate that Fur positively modulates H. pylori J99 motility through interfering with bacterial flagellar switching. © 2017 John Wiley & Sons Ltd.

The role of the dynein light intermediate chain in retrograde IFT and flagellar function in Chlamydomonas

PubMed Central

Reck, Jaimee; Schauer, Alexandria M.; VanderWaal Mills, Kristyn; Bower, Raqual; Tritschler, Douglas; Perrone, Catherine A.; Porter, Mary E.

2016-01-01

The assembly of cilia and flagella depends on the activity of two microtubule motor complexes, kinesin-2 and dynein-2/1b, but the specific functions of the different subunits are poorly defined. Here we analyze Chlamydomonas strains expressing different amounts of the dynein 1b light intermediate chain (D1bLIC). Disruption of D1bLIC alters the stability of the dynein 1b complex and reduces both the frequency and velocity of retrograde intraflagellar transport (IFT), but it does not eliminate retrograde IFT. Flagellar assembly, motility, gliding, and mating are altered in a dose-dependent manner. iTRAQ-based proteomics identifies a small subset of proteins that are significantly reduced or elevated in d1blic flagella. Transformation with D1bLIC-GFP rescues the mutant phenotypes, and D1bLIC-GFP assembles into the dynein 1b complex at wild-type levels. D1bLIC-GFP is transported with anterograde IFT particles to the flagellar tip, dissociates into smaller particles, and begins processive retrograde IFT in <2 s. These studies demonstrate the role of D1bLIC in facilitating the recycling of IFT subunits and other proteins, identify new components potentially involved in the regulation of IFT, flagellar assembly, and flagellar signaling, and provide insight into the role of D1bLIC and retrograde IFT in other organisms. PMID:27251063

The Glycosylphosphatidylinositol-PLC in Trypanosoma brucei Forms a Linear Array on the Exterior of the Flagellar Membrane Before and After Activation

PubMed Central

Hanrahan, Orla; Webb, Helena; O'Byrne, Robert; Brabazon, Elaine; Treumann, Achim; Sunter, Jack D.; Carrington, Mark; Voorheis, H. Paul

2009-01-01

Bloodstream forms of Trypanosoma brucei contain a glycosylphosphatidylinositol-specific phospholipase C (GPI-PLC) that cleaves the GPI-anchor of the variable surface glycoprotein (VSG). Its location in trypanosomes has been controversial. Here, using confocal microscopy and surface labelling techniques, we show that the GPI-PLC is located exclusively in a linear array on the outside of the flagellar membrane, close to the flagellar attachment zone, but does not co-localize with the flagellar attachment zone protein, FAZ1. Consequently, the GPI-PLC and the VSG occupy the same plasma membrane leaflet, which resolves the topological problem associated with the cleavage reaction if the VSG and the GPI-PLC were on opposite sides of the membrane. The exterior location requires the enzyme to be tightly regulated to prevent VSG release under basal conditions. During stimulated VSG release in intact cells, the GPI-PLC did not change location, suggesting that the release mechanism involves lateral diffusion of the VSG in the plane of the membrane to the fixed position of the GPI-PLC. PMID:19503825

Mechanoregulation of molecular motors in flagella

NASA Astrophysics Data System (ADS)

Gadelha, Hermes

2014-11-01

Molecular motors are nano-biological machines responsible for exerting forces that drive movement in living organisms, from cargo transport to cell division and motility. Interestingly, despite the inherent complexity of many interacting motors, order and structure may arise naturally, as exemplified by the harmonic, self-organized undulatory motion of the flagellum. The real mechanisms behind this collective spontaneous oscillation are still unknown, and it is challenging task to measure experimentally the molecular motor dynamics within the flagellar structure in real time. In this talk we will explore different competing hypotheses that are capable of generating flagellar bending waves that ``resemble'' in-vitro observations, emphasizing the need for further mathematical analysis and model validation. It also highlight that this is a fertile and challenging area of inter-disciplinary research for applied mathematicians and demonstrates the importance of future observational and theoretical studies in understanding the underlying mechanics of these motile cell appendages.

Fuel of the Bacterial Flagellar Type III Protein Export Apparatus.

PubMed

Minamino, Tohru; Kinoshita, Miki; Namba, Keiichi

2017-01-01

The flagellar type III export apparatus utilizes ATP and proton motive force (PMF) across the cytoplasmic membrane as the energy sources and transports flagellar component proteins from the cytoplasm to the distal growing end of the growing structure to construct the bacterial flagellum beyond the cellular membranes. The flagellar type III export apparatus coordinates flagellar protein export with assembly by ordered export of substrates to parallel with their order of the assembly. The export apparatus is composed of a PMF-driven transmembrane export gate complex and a cytoplasmic ATPase complex. Since the ATPase complex is dispensable for flagellar protein export, PMF is the primary fuel for protein unfolding and translocation. Interestingly, the export gate complex can also use sodium motive force across the cytoplasmic membrane in addition to PMF when the ATPase complex does not work properly. Here, we describe experimental protocols, which have allowed us to identify the export substrate class and the primary fuel of the flagellar type III protein export apparatus in Salmonella enterica serovar Typhimurium.

Polar Flagellar Motility of the Vibrionaceae

PubMed Central

McCarter, Linda L.

2001-01-01

Polar flagella of Vibrio species can rotate at speeds as high as 100,000 rpm and effectively propel the bacteria in liquid as fast as 60 μm/s. The sodium motive force powers rotation of the filament, which acts as a propeller. The filament is complex, composed of multiple subunits, and sheathed by an extension of the cell outer membrane. The regulatory circuitry controlling expression of the polar flagellar genes of members of the Vibrionaceae is different from the peritrichous system of enteric bacteria or the polar system of Caulobacter crescentus. The scheme of gene control is also pertinent to other members of the gamma purple bacteria, in particular to Pseudomonas species. This review uses the framework of the polar flagellar system of Vibrio parahaemolyticus to provide a synthesis of what is known about polar motility systems of the Vibrionaceae. In addition to its propulsive role, the single polar flagellum of V. parahaemolyticus is believed to act as a tactile sensor controlling surface-induced gene expression. Under conditions that impede rotation of the polar flagellum, an alternate, lateral flagellar motility system is induced that enables movement through viscous environments and over surfaces. Although the dual flagellar systems possess no shared structural components and although distinct type III secretion systems direct the simultaneous placement and assembly of polar and lateral organelles, movement is coordinated by shared chemotaxis machinery. PMID:11528005

Nonlinear amplitude dynamics in flagellar beating

NASA Astrophysics Data System (ADS)

Oriola, David; Gadêlha, Hermes; Casademunt, Jaume

2017-03-01

The physical basis of flagellar and ciliary beating is a major problem in biology which is still far from completely understood. The fundamental cytoskeleton structure of cilia and flagella is the axoneme, a cylindrical array of microtubule doublets connected by passive cross-linkers and dynein motor proteins. The complex interplay of these elements leads to the generation of self-organized bending waves. Although many mathematical models have been proposed to understand this process, few attempts have been made to assess the role of dyneins on the nonlinear nature of the axoneme. Here, we investigate the nonlinear dynamics of flagella by considering an axonemal sliding control mechanism for dynein activity. This approach unveils the nonlinear selection of the oscillation amplitudes, which are typically either missed or prescribed in mathematical models. The explicit set of nonlinear equations are derived and solved numerically. Our analysis reveals the spatio-temporal dynamics of dynein populations and flagellum shape for different regimes of motor activity, medium viscosity and flagellum elasticity. Unstable modes saturate via the coupling of dynein kinetics and flagellum shape without the need of invoking a nonlinear axonemal response. Hence, our work reveals a novel mechanism for the saturation of unstable modes in axonemal beating.

Nonlinear amplitude dynamics in flagellar beating.

PubMed

Oriola, David; Gadêlha, Hermes; Casademunt, Jaume

2017-03-01

The physical basis of flagellar and ciliary beating is a major problem in biology which is still far from completely understood. The fundamental cytoskeleton structure of cilia and flagella is the axoneme, a cylindrical array of microtubule doublets connected by passive cross-linkers and dynein motor proteins. The complex interplay of these elements leads to the generation of self-organized bending waves. Although many mathematical models have been proposed to understand this process, few attempts have been made to assess the role of dyneins on the nonlinear nature of the axoneme. Here, we investigate the nonlinear dynamics of flagella by considering an axonemal sliding control mechanism for dynein activity. This approach unveils the nonlinear selection of the oscillation amplitudes, which are typically either missed or prescribed in mathematical models. The explicit set of nonlinear equations are derived and solved numerically. Our analysis reveals the spatio-temporal dynamics of dynein populations and flagellum shape for different regimes of motor activity, medium viscosity and flagellum elasticity. Unstable modes saturate via the coupling of dynein kinetics and flagellum shape without the need of invoking a nonlinear axonemal response. Hence, our work reveals a novel mechanism for the saturation of unstable modes in axonemal beating.

Nonlinear amplitude dynamics in flagellar beating

PubMed Central

Casademunt, Jaume

2017-01-01

The physical basis of flagellar and ciliary beating is a major problem in biology which is still far from completely understood. The fundamental cytoskeleton structure of cilia and flagella is the axoneme, a cylindrical array of microtubule doublets connected by passive cross-linkers and dynein motor proteins. The complex interplay of these elements leads to the generation of self-organized bending waves. Although many mathematical models have been proposed to understand this process, few attempts have been made to assess the role of dyneins on the nonlinear nature of the axoneme. Here, we investigate the nonlinear dynamics of flagella by considering an axonemal sliding control mechanism for dynein activity. This approach unveils the nonlinear selection of the oscillation amplitudes, which are typically either missed or prescribed in mathematical models. The explicit set of nonlinear equations are derived and solved numerically. Our analysis reveals the spatio-temporal dynamics of dynein populations and flagellum shape for different regimes of motor activity, medium viscosity and flagellum elasticity. Unstable modes saturate via the coupling of dynein kinetics and flagellum shape without the need of invoking a nonlinear axonemal response. Hence, our work reveals a novel mechanism for the saturation of unstable modes in axonemal beating. PMID:28405357

Real-Time Imaging of Fluorescent Flagellar Filaments of Rhizobium lupini H13-3: Flagellar Rotation and pH-Induced Polymorphic Transitions

PubMed Central

Scharf, Birgit

2002-01-01

The soil bacterium Rhizobium lupini H13-3 has complex right-handed flagellar filaments with unusual ridged, grooved surfaces. Clockwise (CW) rotation propels the cells forward, and course changes (tumbling) result from changes in filament speed instead of the more common change in direction of rotation. In view of these novelties, fluorescence labeling was used to analyze the behavior of single flagellar filaments during swimming and tumbling, leading to a model for directional changes in R. lupini. Also, flagellar filaments were investigated for helical conformational changes, which have not been previously shown for complex filaments. During full-speed CW rotation, the flagellar filaments form a propulsive bundle that pushes the cell on a straight path. Tumbling is caused by asynchronous deceleration and stops of individual filaments, resulting in dissociation of the propulsive bundle. R. lupini tumbles were not accompanied by helical conformational changes as are tumbles in other organisms including enteric bacteria. However, when pH was experimentally changed, four different polymorphic forms were observed. At a physiological pH of 7, normal flagellar helices were characterized by a pitch angle of 30°, a pitch of 1.36 μm, and a helical diameter of 0.50 μm. As pH increased from 9 to 11, the helices transformed from normal to semicoiled to straight. As pH decreased from 5 to 3, the helices transformed from normal to curly to straight. Transient conformational changes were also noted at high viscosity, suggesting that the R. lupini flagellar filament may adapt to high loads in viscous environments (soil) by assuming hydrodynamically favorable conformations. PMID:12374832

Emergence of flagellar beating from the collective behavior of individual ATP-powered dyneins

NASA Astrophysics Data System (ADS)

Namdeo, S.; Onck, P. R.

2016-10-01

Flagella are hair-like projections from the surface of eukaryotic cells, and they play an important role in many cellular functions, such as cell-motility. The beating of flagella is enabled by their internal architecture, the axoneme, and is powered by a dense distribution of motor proteins, dyneins. The dyneins deliver the required mechanical work through the hydrolysis of ATP. Although the dynein-ATP cycle, the axoneme microstructure, and the flagellar-beating kinematics are well studied, their integration into a coherent picture of ATP-powered flagellar beating is still lacking. Here we show that a time-delayed negative-work-based switching mechanism is able to convert the individual sliding action of hundreds of dyneins into a regular overall beating pattern leading to propulsion. We developed a computational model based on a minimal representation of the axoneme consisting of two representative doublet microtubules connected by nexin links. The relative sliding of the microtubules is incorporated by modeling two groups of ATP-powered dyneins, each responsible for sliding in opposite directions. A time-delayed switching mechanism is postulated, which is key in converting the local individual sliding action of multiple dyneins into global beating. Our results demonstrate that an overall nonreciprocal beating pattern can emerge with time due to the spatial and temporal coordination of the individual dyneins. These findings provide insights in the fundamental working mechanism of axonemal dyneins and could possibly open new research directions in the field of flagellar motility.

Emergence of flagellar beating from the collective behavior of individual ATP-powered dyneins.

PubMed

Namdeo, S; Onck, P R

2016-10-01

Flagella are hair-like projections from the surface of eukaryotic cells, and they play an important role in many cellular functions, such as cell-motility. The beating of flagella is enabled by their internal architecture, the axoneme, and is powered by a dense distribution of motor proteins, dyneins. The dyneins deliver the required mechanical work through the hydrolysis of ATP. Although the dynein-ATP cycle, the axoneme microstructure, and the flagellar-beating kinematics are well studied, their integration into a coherent picture of ATP-powered flagellar beating is still lacking. Here we show that a time-delayed negative-work-based switching mechanism is able to convert the individual sliding action of hundreds of dyneins into a regular overall beating pattern leading to propulsion. We developed a computational model based on a minimal representation of the axoneme consisting of two representative doublet microtubules connected by nexin links. The relative sliding of the microtubules is incorporated by modeling two groups of ATP-powered dyneins, each responsible for sliding in opposite directions. A time-delayed switching mechanism is postulated, which is key in converting the local individual sliding action of multiple dyneins into global beating. Our results demonstrate that an overall nonreciprocal beating pattern can emerge with time due to the spatial and temporal coordination of the individual dyneins. These findings provide insights in the fundamental working mechanism of axonemal dyneins and could possibly open new research directions in the field of flagellar motility.

Step-wise loss of bacterial flagellar torsion confers progressive phagocytic evasion.

PubMed

Lovewell, Rustin R; Collins, Ryan M; Acker, Julie L; O'Toole, George A; Wargo, Matthew J; Berwin, Brent

2011-09-01

Phagocytosis of bacteria by innate immune cells is a primary method of bacterial clearance during infection. However, the mechanisms by which the host cell recognizes bacteria and consequentially initiates phagocytosis are largely unclear. Previous studies of the bacterium Pseudomonas aeruginosa have indicated that bacterial flagella and flagellar motility play an important role in colonization of the host and, importantly, that loss of flagellar motility enables phagocytic evasion. Here we use molecular, cellular, and genetic methods to provide the first formal evidence that phagocytic cells recognize bacterial motility rather than flagella and initiate phagocytosis in response to this motility. We demonstrate that deletion of genes coding for the flagellar stator complex, which results in non-swimming bacteria that retain an initial flagellar structure, confers resistance to phagocytic binding and ingestion in several species of the gamma proteobacterial group of Gram-negative bacteria, indicative of a shared strategy for phagocytic evasion. Furthermore, we show for the first time that susceptibility to phagocytosis in swimming bacteria is proportional to mot gene function and, consequently, flagellar rotation since complementary genetically- and biochemically-modulated incremental decreases in flagellar motility result in corresponding and proportional phagocytic evasion. These findings identify that phagocytic cells respond to flagellar movement, which represents a novel mechanism for non-opsonized phagocytic recognition of pathogenic bacteria.

Load Response of the Flagellar Beat

NASA Astrophysics Data System (ADS)

Klindt, Gary S.; Ruloff, Christian; Wagner, Christian; Friedrich, Benjamin M.

2016-12-01

Cilia and flagella exhibit regular bending waves that perform mechanical work on the surrounding fluid, to propel cellular swimmers and pump fluids inside organisms. Here, we quantify a force-velocity relationship of the beating flagellum, by exposing flagellated Chlamydomonas cells to controlled microfluidic flows. A simple theory of flagellar limit-cycle oscillations, calibrated by measurements in the absence of flow, reproduces this relationship quantitatively. We derive a link between the energy efficiency of the flagellar beat and its ability to synchronize to oscillatory flows.

Kinesin regulation dynamics through cargo delivery, a single molecule investigation

NASA Astrophysics Data System (ADS)

Kovacs, Anthony; Kessler, Jonathan; Lin, Huawen; Dutcher, Susan; Wang, Yan Mei

2015-03-01

Kinesins are microtubule-based motors that deliver cargo to their destinations in a highly regulated manner. Although in recent years numerous regulators of cargo delivery have been identified, the regulation mechanism of kinesin through the cargo delivery and recycling process is not known. By performing single molecule fluorescence imaging measurements in Chlamydomonas flagella, which are 200 nm in diameter, 10 microns in length, and contain 9 sets of microtubule doublets, we tracked the intraflagellar transport (IFT) trains, BBSome cargo, and kinesin-2 motors through the cargo delivery process and determined the aforementioned dynamics. Upon arrival at the microtubule plus end at the flagellar tip, (1) IFT trains and BBSome cargo remain intact, dissociate together from kinesins and microtubules, and diffuse along flagellar membrane for a mean of 2.3 sec before commencing retrograde travel. (2) Kinesin motors remain bound to and diffuse along microtubules for 1.3 sec before dissociating into the flagellar lumen for recycling.

Step-Wise Loss of Bacterial Flagellar Torsion Confers Progressive Phagocytic Evasion

PubMed Central

Lovewell, Rustin R.; Collins, Ryan M.; Acker, Julie L.; O'Toole, George A.; Wargo, Matthew J.; Berwin, Brent

2011-01-01

Phagocytosis of bacteria by innate immune cells is a primary method of bacterial clearance during infection. However, the mechanisms by which the host cell recognizes bacteria and consequentially initiates phagocytosis are largely unclear. Previous studies of the bacterium Pseudomonas aeruginosa have indicated that bacterial flagella and flagellar motility play an important role in colonization of the host and, importantly, that loss of flagellar motility enables phagocytic evasion. Here we use molecular, cellular, and genetic methods to provide the first formal evidence that phagocytic cells recognize bacterial motility rather than flagella and initiate phagocytosis in response to this motility. We demonstrate that deletion of genes coding for the flagellar stator complex, which results in non-swimming bacteria that retain an initial flagellar structure, confers resistance to phagocytic binding and ingestion in several species of the gamma proteobacterial group of Gram-negative bacteria, indicative of a shared strategy for phagocytic evasion. Furthermore, we show for the first time that susceptibility to phagocytosis in swimming bacteria is proportional to mot gene function and, consequently, flagellar rotation since complementary genetically- and biochemically-modulated incremental decreases in flagellar motility result in corresponding and proportional phagocytic evasion. These findings identify that phagocytic cells respond to flagellar movement, which represents a novel mechanism for non-opsonized phagocytic recognition of pathogenic bacteria. PMID:21949654

A coordinated sequence of distinct flagellar waveforms enables a sharp flagellar turn mediated by squid sperm pH-taxis.

PubMed

Iida, Tomohiro; Iwata, Yoko; Mohri, Tatsuma; Baba, Shoji A; Hirohashi, Noritaka

2017-10-11

Animal spermatozoa navigate by sensing ambient chemicals to reach the site of fertilization. Generally, such chemicals derive from the female reproductive organs or cells. Exceptionally, squid spermatozoa mutually release and perceive carbon dioxide to form clusters after ejaculation. We previously identified the pH-taxis by which each spermatozoon can execute a sharp turn, but how flagellar dynamics enable this movement remains unknown. Here, we show that initiation of the turn motion requires a swim down a steep proton gradient (a theoretical estimation of ≥0.025 pH/s), crossing a threshold pH value of ~5.5. Time-resolved kinematic analysis revealed that the turn sequence results from the rhythmic exercise of two flagellar motions: a stereotypical flagellar 'bent-cane' shape followed by asymmetric wave propagation, which enables a sharp turn in the realm of low Reynolds numbers. This turning episode is terminated by an 'overshoot' trajectory that differs from either straight-line motility or turning. As with bidirectional pH-taxes in some bacteria, squid spermatozoa also showed repulsion from strong acid conditions with similar flagellar kinematics as in positive pH-taxis. These findings indicate that squid spermatozoa might have a unique reorientation mechanism, which could be dissimilar to that of classical egg-guided sperm chemotaxis in other marine invertebrates.

Clinically Relevant Levels of 4-Aminopyridine Strengthen Physiological Responses in Intact Motor Circuits in Rats, Especially After Pyramidal Tract Injury.

PubMed

Sindhurakar, Anil; Mishra, Asht M; Gupta, Disha; Iaci, Jennifer F; Parry, Tom J; Carmel, Jason B

2017-04-01

4-Aminopyridine (4-AP) is a Food and Drug Administration-approved drug to improve motor function in people with multiple sclerosis. Preliminary results suggest the drug may act on intact neural circuits and not just on demyelinated ones. To determine if 4-AP at clinically relevant levels alters the excitability of intact motor circuits. In anesthetized rats, electrodes were placed over motor cortex and the dorsal cervical spinal cord for electrical stimulation, and electromyogram electrodes were inserted into biceps muscle to measure responses. The motor responses to brain and spinal cord stimulation were measured before and for 5 hours after 4-AP administration both in uninjured rats and rats with a cut lesion of the pyramidal tract. Blood was collected at the same time as electrophysiology to determine drug plasma concentration with a goal of 20 to 100 ng/mL. We first determined that a bolus infusion of 0.32 mg/kg 4-AP was optimal: it produced on average 61.5 ± 1.8 ng/mL over the 5 hours after infusion. This dose of 4-AP increased responses to spinal cord stimulation by 1.3-fold in uninjured rats and 3-fold in rats with pyramidal tract lesion. Responses to cortical stimulation also increased by 2-fold in uninjured rats and up to 4-fold in the injured. Clinically relevant levels of 4-AP strongly augment physiological responses in intact circuits, an effect that was more robust after partial injury, demonstrating its broad potential in treating central nervous system injuries.

Reactions of chicken sera to recombinant Campylobacter jejuni flagellar proteins.

PubMed

Yeh, Hung-Yueh; Hiett, Kelli L; Line, John E

2015-03-01

Campylobacter jejuni is a Gram-negative spiral rod bacterium and is the leading but underreported bacterial food-borne pathogen that causes human campylobacteriosis worldwide. Raw or undercooked poultry products are regarded as a major source for human infection. C. jejuni flagella have been implicated in colonization and adhesion to the mucosal surface of chicken gastrointestinal tracts. Therefore, flagellar proteins would be the excellent targets for further investigation. In this report, we used the recombinant technology to generate a battery of C. jejuni flagellar proteins, which were purified by His tag affinity chromatography and determined antigenic profiles of these recombinant flagellar proteins using sera from chickens older than 6 weeks of age. The immunoblot results demonstrate that each chicken serum reacted to various numbers of recombinant flagellar proteins. Among these recombinant proteins, chicken sera reacted predominantly to the FlgE1, FlgK, FlhF, FliG and FliY proteins. These antibody screening results provide a rationale for further evaluation of these recombinant flagellar proteins as potential vaccines for chickens to improve food safety as well as investigation of host immune response to C. jejuni.

The Flagellar Hook Protein, FlgE, of Salmonella enterica Serovar Typhimurium Is Posttranscriptionally Regulated in Response to the Stage of Flagellar Assembly

PubMed Central

Bonifield, Heather R.; Yamaguchi, Shigeru; Hughes, Kelly T.

2000-01-01

We investigated the posttranscriptional regulation of flgE, a class 2 gene that encodes the hook subunit protein of the flagella. RNase protection assays demonstrated that the flgE gene was transcribed at comparable levels in numerous strains defective in known steps of flagellar assembly. However, Western analyses of these strains demonstrated substantial differences in FlgE protein levels. Although wild-type FlgE levels were observed in strains with deletions of genes encoding components of the switch complex and the flagellum-specific secretion apparatus, no protein was detected in a strain with deletions of the rod, ring, and hook-associated proteins. To determine whether FlgE levels were affected by the stage of hook–basal-body assembly, Western analysis was performed on strains with mutations at individual loci encompassed by the deletion. FlgE protein was undetectable in rod mutants, intermediate in ring mutants, and wild type in hook-associated protein mutants. The lack of negative regulation in switch complex and flagellum-specific secretion apparatus deletion mutants blocked for flagellar construction prior to rod assembly suggests that these structures play a role in the negative regulation of FlgE. Quantitative Western analyses of numerous flagellar mutants indicate that FlgE levels reflect the stage at which flagellar assembly is blocked. These data provide evidence for negative posttranscriptional regulation of FlgE in response to the stage of flagellar assembly. PMID:10869084

The flaA locus of Bacillus subtilis is part of a large operon coding for flagellar structures, motility functions, and an ATPase-like polypeptide.

PubMed Central

Albertini, A M; Caramori, T; Crabb, W D; Scoffone, F; Galizzi, A

1991-01-01

We cloned and sequenced 8.3 kb of Bacillus subtilis DNA corresponding to the flaA locus involved in flagellar biosynthesis, motility, and chemotaxis. The DNA sequence revealed the presence of 10 complete and 2 incomplete open reading frames. Comparison of the deduced amino acid sequences to data banks showed similarities of nine of the deduced products to a number of proteins of Escherichia coli and Salmonella typhimurium for which a role in flagellar functioning has been directly demonstrated. In particular, the sequence data suggest that the flaA operon codes for the M-ring protein, components of the motor switch, and the distal part of the basal-body rod. The gene order is remarkably similar to that described for region III of the enterobacterial flagellar regulon. One of the open reading frames was translated into a protein with 48% amino acid identity to S. typhimurium FliI and 29% identity to the beta subunit of E. coli ATP synthase. PMID:1828465

Divalent Cation Control of Flagellar Motility in African Trypanosomes

NASA Astrophysics Data System (ADS)

Westergard, Anna M.; Hutchings, Nathan R.

2005-03-01

Changes in calcium concentration have been shown to dynamically affect flagellar motility in several eukaryotic systems. The African trypanosome is a monoflagellated protozoan parasite and the etiological agent of sleeping sickness. Although cell motility has been implicated in disease progression, very little is currently known about biochemical control of the trypanosome flagellum. In this study, we assess the effects of extracellular changes in calcium and nickel concentration on trypanosome flagellar movement. Using a flow through chamber, we determine the relative changes in motility in individual trypanosomes in response to various concentrations of calcium and nickel, respectively. Extracellular concentrations of calcium and nickel (as low as 100 micromolar) significantly inhibit trypanosome cell motility. The effects are reversible, as indicated by the recovery of motion after removal of the calcium or nickel from the chamber. We are currently investigating the specific changes in flagellar oscillation and coordination that result from calcium and nickel, respectively. These results verify the presence of a calcium-responsive signaling mechanism(s) that regulates flagellar beat in trypanosomes.

Ocean acidification reduces sperm flagellar motility in broadcast spawning reef invertebrates.

PubMed

Morita, Masaya; Suwa, Ryota; Iguchi, Akira; Nakamura, Masako; Shimada, Kazuaki; Sakai, Kazuhiko; Suzuki, Atsushi

2010-05-01

Ocean acidification is now recognized as a threat to marine ecosystems; however, the effect of ocean acidification on fertilization in marine organisms is still largely unknown. In this study, we focused on sperm flagellar motility in broadcast spawning reef invertebrates (a coral and a sea cucumber). Below pH 7.7, the pH predicted to occur within the next 100 years, sperm flagellar motility was seriously impaired in these organisms. Considering that sperm flagellar motility is indispensable for transporting the paternal haploid genome for fertilization, fertilization taking place in seawater may decline in the not too distant future. Urgent surveys are necessary for a better understanding of the physiological consequences of ocean acidification on sperm flagellar motility in a wide range of marine invertebrates.

Themes and Variations: Regulation of RpoN-Dependent Flagellar Genes across Diverse Bacterial Species

PubMed Central

Tsang, Jennifer; Hoover, Timothy R.

2014-01-01

Flagellar biogenesis in bacteria is a complex process in which the transcription of dozens of structural and regulatory genes is coordinated with the assembly of the flagellum. Although the overall process of flagellar biogenesis is conserved among bacteria, the mechanisms used to regulate flagellar gene expression vary greatly among different bacterial species. Many bacteria use the alternative sigma factor σ 54 (also known as RpoN) to transcribe specific sets of flagellar genes. These bacteria include members of the Epsilonproteobacteria (e.g., Helicobacter pylori and Campylobacter jejuni), Gammaproteobacteria (e.g., Vibrio and Pseudomonas species), and Alphaproteobacteria (e.g., Caulobacter crescentus). This review characterizes the flagellar transcriptional hierarchies in these bacteria and examines what is known about how flagellar gene regulation is linked with other processes including growth phase, quorum sensing, and host colonization. PMID:24672734

Regulation of flagellar assembly by glycogen synthase kinase 3 in Chlamydomonas reinhardtii.

PubMed

Wilson, Nedra F; Lefebvre, Paul A

2004-10-01

Chlamydomonas reinhardtii controls flagellar assembly such that flagella are of an equal and predetermined length. Previous studies demonstrated that lithium, an inhibitor of glycogen synthase kinase 3 (GSK3), induced flagellar elongation, suggesting that a lithium-sensitive signal transduction pathway regulated flagellar length (S. Nakamura, H. Takino, and M. K. Kojima, Cell Struct. Funct. 12:369-374, 1987). Here, we demonstrate that lithium treatment depletes the pool of flagellar proteins from the cell body and that the heterotrimeric kinesin Fla10p accumulates in flagella. We identify GSK3 in Chlamydomonas and demonstrate that its kinase activity is inhibited by lithium in vitro. The tyrosine-phosphorylated, active form of GSK3 was enriched in flagella and GSK3 associated with the axoneme in a phosphorylation-dependent manner. The level of active GSK3 correlated with flagellar length; early during flagellar regeneration, active GSK3 increased over basal levels. This increase in active GSK3 was rapidly lost within 30 min of regeneration as the level of active GSK3 decreased relative to the predeflagellation level. Taken together, these results suggest a possible role for GSK3 in regulating the assembly and length of flagella.

Hierarchical protein export mechanism of the bacterial flagellar type III protein export apparatus.

PubMed

Minamino, Tohru

2018-06-01

The bacterial flagellum is supramolecular motility machinery consisting of the basal body, the hook and the filament. Flagellar proteins are translocated across the cytoplasmic membrane via a type III protein export apparatus, diffuse down the central channel of the growing structure and assemble at the distal end. Flagellar assembly begins with the basal body, followed by the hook and finally the filament. The completion of hook assembly is the most important morphological checkpoint of the sequential flagellar assembly process. When the hook reaches its mature length of about 55 nm in Salmonella enterica, the type III protein export apparatus switches export specificity from proteins required for the structure and assembly of the hook to those responsible for filament assembly, thereby terminating hook assembly and initiating filament assembly. Three flagellar proteins, namely FliK, FlhB and FlhA, are responsible for this substrate specificity switching. Upon completion of the switching event, interactions among FlhA, the cytoplasmic ATPase complex and flagellar type III export chaperones establish the assembly order of the filament at the hook tip. Here, we describe our current understanding of a hierarchical protein export mechanism used in flagellar type III protein export.

Magnetic Propulsion of Microswimmers with DNA-Based Flagellar Bundles.

PubMed

Maier, Alexander M; Weig, Cornelius; Oswald, Peter; Frey, Erwin; Fischer, Peer; Liedl, Tim

2016-02-10

We show that DNA-based self-assembly can serve as a general and flexible tool to construct artificial flagella of several micrometers in length and only tens of nanometers in diameter. By attaching the DNA flagella to biocompatible magnetic microparticles, we provide a proof of concept demonstration of hybrid structures that, when rotated in an external magnetic field, propel by means of a flagellar bundle, similar to self-propelling peritrichous bacteria. Our theoretical analysis predicts that flagellar bundles that possess a length-dependent bending stiffness should exhibit a superior swimming speed compared to swimmers with a single appendage. The DNA self-assembly method permits the realization of these improved flagellar bundles in good agreement with our quantitative model. DNA flagella with well-controlled shape could fundamentally increase the functionality of fully biocompatible nanorobots and extend the scope and complexity of active materials.

Flagellar region 3b supports strong expression of integrated DNA and the highest chromosomal integration efficiency of the Escherichia coli flagellar regions.

PubMed

Juhas, Mario; Ajioka, James W

2015-07-01

The Gram-negative bacterium Escherichia coli is routinely used as the chassis for a variety of biotechnology and synthetic biology applications. Identification and analysis of reliable chromosomal integration and expression target loci is crucial for E. coli engineering. Chromosomal loci differ significantly in their ability to support integration and expression of the integrated genetic circuits. In this study, we investigate E. coli K12 MG1655 flagellar regions 2 and 3b. Integration of the genetic circuit into seven and nine highly conserved genes of the flagellar regions 2 (motA, motB, flhD, flhE, cheW, cheY and cheZ) and 3b (fliE, F, G, J, K, L, M, P, R), respectively, showed significant variation in their ability to support chromosomal integration and expression of the integrated genetic circuit. While not reducing the growth of the engineered strains, the integrations into all 16 target sites led to the loss of motility. In addition to high expression, the flagellar region 3b supports the highest efficiency of integration of all E. coli K12 MG1655 flagellar regions and is therefore potentially the most suitable for the integration of synthetic genetic circuits. © 2015 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Automatic Online Motor Control Is Intact in Parkinson's Disease With and Without Perceptual Awareness.

PubMed

Merritt, Kate E; Seergobin, Ken N; Mendonça, Daniel A; Jenkins, Mary E; Goodale, Melvyn A; MacDonald, Penny A

2017-01-01

In the double-step paradigm, healthy human participants automatically correct reaching movements when targets are displaced. Motor deficits are prominent in Parkinson's disease (PD) patients. In the lone investigation of online motor correction in PD using the double-step task, a recent study found that PD patients performed unconscious adjustments appropriately but seemed impaired for consciously-perceived modifications. Conscious perception of target movement was achieved by linking displacement to movement onset. PD-related bradykinesia disproportionately prolonged preparatory phases for movements to original target locations for patients, potentially accounting for deficits. Eliminating this confound in a double-step task, we evaluated the effect of conscious awareness of trajectory change on online motor corrections in PD. On and off dopaminergic therapy, PD patients ( n = 14) and healthy controls ( n = 14) reached to peripheral visual targets that remained stationary or unexpectedly moved during an initial saccade. Saccade latencies in PD are comparable to controls'. Hence, target displacements occurred at equal times across groups. Target jump size affected conscious awareness, confirmed in an independent target displacement judgment task. Small jumps were subliminal, but large target displacements were consciously perceived. Contrary to the previous result, PD patients performed online motor corrections normally and automatically, irrespective of conscious perception. Patients evidenced equivalent movement durations for jump and stay trials, and trajectories for patients and controls were identical, irrespective of conscious perception. Dopaminergic therapy had no effect on performance. In summary, online motor control is intact in PD, unaffected by conscious perceptual awareness. The basal ganglia are not implicated in online corrective responses.

Transcriptional Control of the Lateral-Flagellar Genes of Bradyrhizobium diazoefficiens.

PubMed

Mongiardini, Elías J; Quelas, J Ignacio; Dardis, Carolina; Althabegoiti, M Julia; Lodeiro, Aníbal R

2017-08-01

Bradyrhizobium diazoefficiens , a soybean N 2 -fixing symbiont, possesses a dual flagellar system comprising a constitutive subpolar flagellum and inducible lateral flagella. Here, we analyzed the genomic organization and biosynthetic regulation of the lateral-flagellar genes. We found that these genes are located in a single genomic cluster, organized in two monocistronic transcriptional units and three operons, one possibly containing an internal transcription start site. Among the monocistronic units is blr6846, homologous to the class IB master regulators of flagellum synthesis in Brucella melitensis and Ensifer meliloti and required for the expression of all the lateral-flagellar genes except lafA2 , whose locus encodes a single lateral flagellin. We therefore named blr6846 lafR ( la teral- f lagellar r egulator). Despite its similarity to two-component response regulators and its possession of a phosphorylatable Asp residue, lafR behaved as an orphan response regulator by not requiring phosphorylation at this site. Among the genes induced by lafR is flbT L , a class III regulator. We observed different requirements for FlbT L in the synthesis of each flagellin subunit. Although the accumulation of lafA1 , but not lafA2 , transcripts required FlbT L , the production of both flagellin polypeptides required FlbT L Moreover, the regulation cascade of this lateral-flagellar regulon appeared to be not as strictly ordered as those found in other bacterial species. IMPORTANCE Bacterial motility seems essential for the free-living style in the environment, and therefore these microorganisms allocate a great deal of their energetic resources to the biosynthesis and functioning of flagella. Despite energetic costs, some bacterial species possess dual flagellar systems, one of which is a primary system normally polar or subpolar, and the other is a secondary, lateral system that is produced only under special circumstances. Bradyrhizobium diazoefficiens , an N 2 -fixing

Glucose induces delocalization of a flagellar biosynthesis protein from the flagellated pole.

PubMed

Park, Soyoung; Park, Young-Ha; Lee, Chang-Ro; Kim, Yeon-Ran; Seok, Yeong-Jae

2016-09-01

To survive in a continuously changing environment, bacteria sense concentration gradients of attractants or repellents, and purposefully migrate until a more favourable habitat is encountered. While glucose is known as the most effective attractant, the flagellar biosynthesis and hence chemotactic motility has been known to be repressed by glucose in some bacteria. To date, the only known regulatory mechanism of the repression of flagellar synthesis by glucose is via downregulation of the cAMP level, as shown in a few members of the family Enterobacteriaceae. Here we show that, in Vibrio vulnificus, the glucose-mediated inhibition of flagellar motility operates by a completely different mechanism. In the presence of glucose, EIIA(Glc) is dephosphorylated and inhibits the polar localization of FapA (flagellar assembly protein A) by sequestering it from the flagellated pole. A loss or delocalization of FapA results in a complete failure of the flagellar biosynthesis and motility. However, when glucose is depleted, EIIA(Glc) is phosphorylated and releases FapA such that free FapA can be localized back to the pole and trigger flagellation. Together, these data provide new insight into a bacterial strategy to reach and stay in the glucose-rich area. © 2016 John Wiley & Sons Ltd.

[Structure and function of the bacterial flagellar type III protein export system in Salmonella
].

PubMed

Minamino, Tohru

2015-01-01

The bacterial flagellum is a filamentous organelle that propels the bacterial cell body in liquid media. For construction of the bacterial flagellum beyond the cytoplasmic membrane, flagellar component proteins are transported by its specific protein export apparatus from the cytoplasm to the distal end of the growing flagellar structure. The flagellar export apparatus consists of a transmembrane export gate complex and a cytoplasmic ATPase ring complex. Flagellar substrate-specific chaperones bind to their cognate substrates in the cytoplasm and escort the substrates to the docking platform of the export gate. The export apparatus utilizes ATP and proton motive force across the cytoplasmic membrane as the energy sources to drive protein export and coordinates protein export with assembly by ordered export of substrates to parallel with their order of assembly. In this review, we summarize our current understanding of the structure and function of the flagellar protein export system in Salmonella enterica serovar Typhimurium.

A quantitative description of flagellar movement in golden hamster spermatozoa.

PubMed

Ishijima, S; Mohri, H

1985-01-01

Flagellar movement of golden hamster spermatozoa obtained from the testis and the caput and cauda epididymides was observed by a light microscope while holding them at their heads with a micropipette. Flagellar movement of capacitated spermatozoa and of reactivated spermatozoa demembranated with Triton X-100 was also observed. Testicular and caput epididymal spermatozoa showed weak movement in Tyrode's solution, whereas cauda epididymal spermatozoa showed vigorous movement. The flagellar bends of the cauda epididymal spermatozoa were almost planar. Capacitated spermatozoa moved with waves of a large amplitude. Demembranated spermatozoa reactivated with ATP only had a latent period before the initiation of flagellar movement, and beat at low frequency, whereas demembranated spermatozoa reactivated with both ATP and cAMP began to move immediately at high frequency. Thrust and hydrodynamic power output were calculated using the parameters for the typical waveforms of cauda epididymal spermatozoa before and after capacitation. The possible role of the large amplitude beat in capacitated spermatozoa is discussed. A comparison of the 'principal' and 'reverse' bends in golden hamster sperm flagella as defined by Woolley (1977) with those in sea urchin sperm flagella suggests that the so-called 'principal' bend in golden hamster sperm flagella corresponds to the reverse bend in sea urchin sperm flagella and vice versa.

Automatic Online Motor Control Is Intact in Parkinson’s Disease With and Without Perceptual Awareness

PubMed Central

Seergobin, Ken N.; Mendonça, Daniel A.

2017-01-01

Abstract In the double-step paradigm, healthy human participants automatically correct reaching movements when targets are displaced. Motor deficits are prominent in Parkinson’s disease (PD) patients. In the lone investigation of online motor correction in PD using the double-step task, a recent study found that PD patients performed unconscious adjustments appropriately but seemed impaired for consciously-perceived modifications. Conscious perception of target movement was achieved by linking displacement to movement onset. PD-related bradykinesia disproportionately prolonged preparatory phases for movements to original target locations for patients, potentially accounting for deficits. Eliminating this confound in a double-step task, we evaluated the effect of conscious awareness of trajectory change on online motor corrections in PD. On and off dopaminergic therapy, PD patients (n = 14) and healthy controls (n = 14) reached to peripheral visual targets that remained stationary or unexpectedly moved during an initial saccade. Saccade latencies in PD are comparable to controls’. Hence, target displacements occurred at equal times across groups. Target jump size affected conscious awareness, confirmed in an independent target displacement judgment task. Small jumps were subliminal, but large target displacements were consciously perceived. Contrary to the previous result, PD patients performed online motor corrections normally and automatically, irrespective of conscious perception. Patients evidenced equivalent movement durations for jump and stay trials, and trajectories for patients and controls were identical, irrespective of conscious perception. Dopaminergic therapy had no effect on performance. In summary, online motor control is intact in PD, unaffected by conscious perceptual awareness. The basal ganglia are not implicated in online corrective responses. PMID:29085900

Isolation and characterization of flagellar filament from zoospores of Dermatophilus congolensis.

PubMed

Hiraizumi, Mieko; Tagawa, Yuichi

2014-09-17

Highly motile zoospores from Dermatophilus congolensis bovine isolates from clinical dermatophilosis in Japan were obtained by culturing at 27°C in an ambient atmosphere on heart infusion agar supplemented with 5% defibrinated sheep blood for 72h or in heart infusion broth for 48h with gentle shaking. After vigorous mechanical agitation of the zoospore suspension, the flagellar filaments detached from motile zoospores and were isolated in the clear gelatinous part of the final pellet by differential centrifugation. Typical morphology of a flagellar filament, with a width of approximately 15nm, was observed in the isolated flagellar filament by electron microscopy. A single major protein (flagellin) band with an apparent molecular mass of 35kDa was detected in the flagellar filament of D. congolensis strain AM-1 and that of 33kDa was detected in strain IT-2 by SDS-PAGE. In immunoblot analysis of whole-cell proteins from seven isolates of D. congolensis, antiserum to strain AM-1 zoospores reacted with the 35-kDa antigen band of strain AM-1, but not with any antigen band of other strains in a similar molecular mass range. In contrast, antiserum to strain IT-2 zoospores reacted with antigen bands at 33kDa from six strains, except strain AM-1. Similar strain-specific reactions of these anti-zoospore sera with isolated flagellar filaments from strains AM-1 and IT-2 were confirmed by immunoblot, indicating the presence of antigenic variations of flagellins of D. congolensis zoospores. Copyright © 2014 Elsevier B.V. All rights reserved.

Intracellular Ca2+ threshold reversibly switches flagellar beat off and on.

PubMed

Sánchez-Cárdenas, C; Montoya, F; Navarrete, F A; Hernández-Cruz, A; Corkidi, G; Visconti, P E; Darszon, A

2018-06-08

Sperm motility is essential for fertilization. The asymmetry of flagellar beat in spermatozoa is finely regulated by intracellular calcium concentration ([Ca2+]i). Recently, we demonstrated that the application of high concentrations (10-20 μM) of the Ca2+ ionophore A23187 promotes sperm immobilization after 10 minutes, and its removal thereafter allows motility recovery, hyperactivation and fertilization. In addition, the same ionophore treatment overcomes infertility observed in sperm from Catsper1-/-, Slo3-/- and Adcy10-/-, but not PMCA4-/-, which strongly suggest that regulation of [Ca2+]i is mandatory for sperm motility and hyperactivation. In this study we found that prior to inducing sperm immobilization, high A23187 concentrations (10 μM) increase flagellar beat. While 5-10 μM A23187 substantially elevates [Ca2+]i and rapidly immobilizes sperm in a few minutes, smaller concentrations (0.5 and 1 μM) provoke smaller [Ca2+]i increases and sperm hyperactivation, confirming that [Ca2+]i increases act as a motility switch. Until now the [Ca2+]i thresholds that switch motility on and off were not fully understood. To study the relationship between [Ca2+]i and flagellar beating, we developed an automatic tool that allows the simultaneous measurement of these two parameters. Individual spermatozoa were treated with A23187 which is then washed to evaluate [Ca2+]i and flagellar beat recovery using the implemented method. We observe that [Ca2+]i must decrease below a threshold concentration range to facilitate subsequent flagellar beat recovery and sperm motility.

Structure and Activity of the Flagellar Rotor Protein FliY

PubMed Central

Sircar, Ria; Greenswag, Anna R.; Bilwes, Alexandrine M.; Gonzalez-Bonet, Gabriela; Crane, Brian R.

2013-01-01

Rotating flagella propel bacteria toward favorable environments. Sense of rotation is determined by the intracellular response regulator CheY, which when phosphorylated (CheY-P) interacts directly with the flagellar motor. In many different types of bacteria, the CheC/CheX/FliY (CXY) family of phosphatases terminates the CheY-P signal. Unlike CheC and CheX, FliY is localized in the flagellar switch complex, which also contains the stator-coupling protein FliG and the target of CheY-P, FliM. The 2.5 Å resolution crystal structure of the FliY catalytic domain from Thermotoga maritima bears strong resemblance to the middle domain of FliM. Regions of FliM that mediate contacts within the rotor compose the phosphatase active sites in FliY. Despite the similarity between FliY and FliM, FliY does not bind FliG and thus is unlikely to be a substitute for FliM in the center of the switch complex. Solution studies indicate that FliY dimerizes through its C-terminal domains, which resemble the Escherichia coli switch complex component FliN. FliY differs topologically from the E. coli chemotaxis phosphatase CheZ but appears to utilize similar structural motifs for CheY dephosphorylation in close analogy to CheX. Recognition properties and phosphatase activities of site-directed mutants identify two pseudosymmetric active sites in FliY (Glu35/Asn38 and Glu132/Asn135), with the second site (Glu132/Asn135) being more active. A putative N-terminal CheY binding domain conserved with FliM is not required for binding CheY-P or phosphatase activity. PMID:23532838

The Flagellar Protein FliL Is Essential for Swimming in Rhodobacter sphaeroides▿ †

PubMed Central

Suaste-Olmos, Fernando; Domenzain, Clelia; Mireles-Rodríguez, José Cruz; Poggio, Sebastian; Osorio, Aurora; Dreyfus, Georges; Camarena, Laura

2010-01-01

In this work we characterize the function of the flagellar protein FliL in Rhodobacter sphaeroides. Our results show that FliL is essential for motility in this bacterium and that in its absence flagellar rotation is highly impaired. A green fluorescent protein (GFP)-FliL fusion forms polar and lateral fluorescent foci that show different spatial dynamics. The presence of these foci is dependent on the expression of the flagellar genes controlled by the master regulator FleQ, suggesting that additional components of the flagellar regulon are required for the proper localization of GFP-FliL. Eight independent pseudorevertants were isolated from the fliL mutant strain. In each of these strains a single nucleotide change in motB was identified. The eight mutations affected only three residues located on the periplasmic side of MotB. Swimming of the suppressor mutants was not affected by the presence of the wild-type fliL allele. Pulldown and yeast two-hybrid assays showed that that the periplasmic domain of FliL is able to interact with itself but not with the periplasmic domain of MotB. From these results we propose that FliL could participate in the coupling of MotB with the flagellar rotor in an indirect fashion. PMID:20889747

Combining d-cycloserine with motor training does not result in improved general motor learning in neurologically intact people or in people with stroke

PubMed Central

Cherry, Kendra M.; Lenze, Eric J.

2014-01-01

Neurological rehabilitation involving motor training has resulted in clinically meaningful improvements in function but is unable to eliminate many of the impairments associated with neurological injury. Thus there is a growing need for interventions that facilitate motor learning during rehabilitation therapy, to optimize recovery. d-Cycloserine (DCS), a partial N-methyl-d-aspartate (NMDA) receptor agonist that enhances neurotransmission throughout the central nervous system (Ressler KJ, Rothbaum BO, Tannenbaum L, Anderson P, Graap K, Zimand E, Hodges L, Davis M. Arch Gen Psychiatry 61: 1136–1144, 2004), has been shown to facilitate declarative and emotional learning. We therefore tested whether combining DCS with motor training facilitates motor learning after stroke in a series of two experiments. Forty-one healthy adults participated in experiment I, and twenty adults with stroke participated in experiment II of this two-session, double-blind study. Session one consisted of baseline assessment, subject randomization, and oral administration of DCS or placebo (250 mg). Subjects then participated in training on a balancing task, a simulated feeding task, and a cognitive task. Subjects returned 1–3 days later for posttest assessment. We found that all subjects had improved performance from pretest to posttest on the balancing task, the simulated feeding task, and the cognitive task. Subjects who were given DCS before motor training, however, did not show enhanced learning on the balancing task, the simulated feeding task, or the associative recognition task compared with subjects given placebo. Moreover, training on the balancing task did not generalize to a similar, untrained balance task. Our findings suggest that DCS does not enhance motor learning or motor skill generalization in neurologically intact adults or in adults with stroke. PMID:24671538

Direction of flagellar rotation in bacterial cell envelopes.

PubMed Central

Ravid, S; Eisenbach, M

1984-01-01

Cell envelopes with functional flagella, isolated from wild-type strains of Escherichia coli and Salmonella typhimurium by formation of spheroplasts with penicillin and subsequent osmotic lysis, demonstrate counterclockwise (CCW)-biased rotation when energized with an electron donor for respiration, DL-lactate. Since the direction of flagellar rotation in bacteria is central to the expression of chemotaxis, we studied the cause of this bias. Our main observations were: (i) spheroplasts acquired a clockwise (CW) bias if instead of being lysed they were further incubated with penicillin; (ii) repellents temporarily caused CW rotation of tethered bacteria and spheroplasts but not of their derived cell envelopes; (iii) deenergizing CW-rotating cheV bacteria by KCN or arsenate treatment caused CCW bias; (iv) cell envelopes isolated from CW-rotating cheC and cheV mutants retained the CW bias, unlike envelopes isolated from cheB and cheZ mutants, which upon cytoplasmic release lost this bias and acquired CCW bias; and (v) an inwardly directed, artificially induced proton current rotated tethered envelopes in CCW direction, but an outwardly directed current was unable to rotate the envelopes. It is concluded that (i) a cytoplasmic constituent is required for the expression of CW rotation (or repression of CCW rotation) in strains which are not defective in the switch; (ii) in the absence of this cytoplasmic constituent, the motor is not reversible in such strains, and it probably is mechanically constricted so as to permit CCW sense of rotation only; (iii) the requirement of CW rotation for ATP is not at the level of the motor or the switch but at one of the preceding functional steps of the chemotaxis machinery; (iv) the cheC and cheV gene products are associated with the cytoplasmic membrane; and (v) direct interaction between the switch-motor system and the repellent sensors is improbable. Images PMID:6370958

Intraflagellar transport particle size scales inversely with flagellar length: revisiting the balance-point length control model.

PubMed

Engel, Benjamin D; Ludington, William B; Marshall, Wallace F

2009-10-05

The assembly and maintenance of eukaryotic flagella are regulated by intraflagellar transport (IFT), the bidirectional traffic of IFT particles (recently renamed IFT trains) within the flagellum. We previously proposed the balance-point length control model, which predicted that the frequency of train transport should decrease as a function of flagellar length, thus modulating the length-dependent flagellar assembly rate. However, this model was challenged by the differential interference contrast microscopy observation that IFT frequency is length independent. Using total internal reflection fluorescence microscopy to quantify protein traffic during the regeneration of Chlamydomonas reinhardtii flagella, we determined that anterograde IFT trains in short flagella are composed of more kinesin-associated protein and IFT27 proteins than trains in long flagella. This length-dependent remodeling of train size is consistent with the kinetics of flagellar regeneration and supports a revised balance-point model of flagellar length control in which the size of anterograde IFT trains tunes the rate of flagellar assembly.

Limiting (zero-load) speed of the rotary motor of Escherichia coli is independent of the number of torque-generating units

PubMed Central

Wang, Bin; Zhang, Rongjing; Yuan, Junhua

2017-01-01

Rotation of the bacterial flagellar motor is driven by multiple torque-generating units (stator elements). The torque-generating dynamics can be understood in terms of the “duty ratio” of the stator elements, that is, the fraction of time a stator element engages with the rotor during its mechanochemical cycle. The dependence of the limiting speed (zero-load speed) of the motor on the number of stator elements is the determining test of the duty ratio, which has been controversial experimentally and theoretically over the past decade. Here, we developed a method combining laser dark-field microscopy and optical trapping to resolve this controversy. We found that the zero-load speed is independent of the number of stator elements for the bacterial flagellar motor in Escherichia coli, demonstrating that these elements have a duty ratio close to 1. PMID:29109285

Limiting (zero-load) speed of the rotary motor of Escherichia coli is independent of the number of torque-generating units.

PubMed

Wang, Bin; Zhang, Rongjing; Yuan, Junhua

2017-11-21

Rotation of the bacterial flagellar motor is driven by multiple torque-generating units (stator elements). The torque-generating dynamics can be understood in terms of the "duty ratio" of the stator elements, that is, the fraction of time a stator element engages with the rotor during its mechanochemical cycle. The dependence of the limiting speed (zero-load speed) of the motor on the number of stator elements is the determining test of the duty ratio, which has been controversial experimentally and theoretically over the past decade. Here, we developed a method combining laser dark-field microscopy and optical trapping to resolve this controversy. We found that the zero-load speed is independent of the number of stator elements for the bacterial flagellar motor in Escherichia coli , demonstrating that these elements have a duty ratio close to 1.

Transcriptional regulation of coordinate changes in flagellar mRNAs during differentiation of Naegleria gruberi amoebae into flagellates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, J.H.; Walsh, C.J.

1988-06-01

The nuclear run-on technique was used to measure the rate of transcription of flagellar genes during the differentiation of Naegleria gruberi amebae into flagellates. Synthesis of mRNAs for the axonemal proteins ..cap alpha..- and BETA-tubulin and flagellar calmodulin, as well as a coordinately regulated poly(A)/sup +/ RNA that codes for an unidentified protein, showed transient increases averaging 22-fold. The rate of synthesis of two poly(A)/sup +/ RNAs common to ameobae and flagellates was low until the transcription of the flagellar genes began to decline, at which time synthesis of the RNAs found in ameobae increased 3- to 10-fold. The observedmore » changes in the rate of transcription can account quantitatively for the 20-fold increase in flagellar mRNA concentration during the differentiation. The data for the flagellar calmodulin gene demonstrate transcriptional regulation for a nontubulin axonemal protein. The data also demonstrate at least two programs of transcriptional regulation during the differentiation and raise the intriguing possibility that some significant fraction of the nearly 200 different proteins of the flagellar axoneme is transcriptionally regulated during the 1 h it takes N. gruberi amebae to form visible flagella.« less

In Vitro Reconstitution of Functional Type III Protein Export and Insights into Flagellar Assembly.

PubMed

Terashima, Hiroyuki; Kawamoto, Akihiro; Tatsumi, Chinatsu; Namba, Keiichi; Minamino, Tohru; Imada, Katsumi

2018-06-26

The type III secretion system (T3SS) forms the functional core of injectisomes, protein transporters that allow bacteria to deliver virulence factors into their hosts for infection, and flagella, which are critical for many pathogens to reach the site of infection. In spite of intensive genetic and biochemical studies, the T3SS protein export mechanism remains unclear due to the difficulty of accurate measurement of protein export in vivo Here, we developed an in vitro flagellar T3S protein transport assay system using an inverted cytoplasmic membrane vesicle (IMV) for accurate and controlled measurements of flagellar protein export. We show that the flagellar T3SS in the IMV fully retains export activity. The flagellar hook was constructed inside the lumen of the IMV by adding purified component proteins externally to the IMV solution. We reproduced the hook length control and export specificity switch in the IMV consistent with that seen in the native cell. Previous in vivo analyses showed that flagellar protein export is driven by proton motive force (PMF) and facilitated by ATP hydrolysis by FliI, a T3SS-specific ATPase. Our in vitro assay recapitulated these previous in vivo observations but furthermore clearly demonstrated that even ATP hydrolysis by FliI alone can drive flagellar protein export. Moreover, this assay showed that addition of the FliH 2 /FliI complex to the assay solution at a concentration similar to that in the cell dramatically enhanced protein export, confirming that the FliH 2 /FliI complex in the cytoplasm is important for effective protein transport. IMPORTANCE The type III secretion system (T3SS) is the functional core of the injectisome, a bacterial protein transporter used to deliver virulence proteins into host cells, and bacterial flagella, critical for many pathogens. The molecular mechanism of protein transport is still unclear due to difficulties in accurate measurements of protein transport under well-controlled conditions in

Flagellar Hook Flexibility Is Essential for Bundle Formation in Swimming Escherichia coli Cells

PubMed Central

Brown, Mostyn T.; Steel, Bradley C.; Silvestrin, Claudio; Wilkinson, David A.; Delalez, Nicolas J.; Lumb, Craig N.; Obara, Boguslaw; Berry, Richard M.

2012-01-01

Swimming Escherichia coli cells are propelled by the rotary motion of their flagellar filaments. In the normal swimming pattern, filaments positioned randomly over the cell form a bundle at the posterior pole. It has long been assumed that the hook functions as a universal joint, transmitting rotation on the motor axis through up to ∼90° to the filament in the bundle. Structural models of the hook have revealed how its flexibility is expected to arise from dynamic changes in the distance between monomers in the helical lattice. In particular, each of the 11 protofilaments that comprise the hook is predicted to cycle between short and long forms, corresponding to the inside and outside of the curved hook, once each revolution of the motor when the hook is acting as a universal joint. To test this, we genetically modified the hook so that it could be stiffened by binding streptavidin to biotinylated monomers, impeding their motion relative to each other. We found that impeding the action of the universal joint resulted in atypical swimming behavior as a consequence of disrupted bundle formation, in agreement with the universal joint model. PMID:22522898

3D structure of eukaryotic flagella in a quiescent state revealed by cryo-electron tomography

PubMed Central

Nicastro, Daniela; McIntosh, J. Richard; Baumeister, Wolfgang

2005-01-01

We have used cryo-electron tomography to investigate the 3D structure and macromolecular organization of intact, frozen-hydrated sea urchin sperm flagella in a quiescent state. The tomographic reconstructions provide information at a resolution better than 6 nm about the in situ arrangements of macromolecules that are key for flagellar motility. We have visualized the heptameric rings of the motor domains in the outer dynein arm complex and determined that they lie parallel to the plane that contains the axes of neighboring flagellar microtubules. Both the material associated with the central pair of microtubules and the radial spokes display a plane of symmetry that helps to explain the planar beat pattern of these flagella. Cryo-electron tomography has proven to be a powerful technique for helping us understand the relationships between flagellar structure and function and the design of macromolecular machines in situ. PMID:16246999

Role of calmodulin and calcineurin in regulating flagellar motility and wave polarity in Leishmania.

PubMed

Mukhopadhyay, Aakash Gautam; Dey, Chinmoy Sankar

2017-11-01

We have previously reported the involvement of cyclic AMP in regulating flagellar waveforms in Leishmania. Here, we investigated the roles of calcium, calmodulin, and calcineurin in flagellar motility regulation in L. donovani. Using high-speed videomicroscopy, we show that calcium-independent calmodulin and calcineurin activity is necessary for motility in Leishmania. Inhibition of calmodulin and calcineurin induced ciliary beats interrupting flagellar beating in both live (in vivo) and ATP-reactivated (in vitro) parasites. Our results indicate that signaling mediated by calmodulin and calcineurin operates antagonistically to cAMP signaling in regulating the waveforms of Leishmania flagellum. These two pathways are possibly involved in maintaining the balance between the two waveforms, essential for responding to environmental cues, survival, and infectivity.

The flagellar master operon flhDC is a pleiotropic regulator involved in motility and virulence of the fish pathogen Yersinia ruckeri.

PubMed

Jozwick, A K S; Graf, J; Welch, T J

2017-03-01

To investigate the function of the master flagellar operon flhDC in the fish pathogen Yersinia ruckeri and compare the effect of a constructed flhD mutation to a naturally occurring fliR mutation causing loss-of-motility in emergent biotype 2 (BT2) strains. Yersinia ruckeri flhD and fliR mutants were constructed in a motile strain. Both mutations caused loss-of-motility, ablation of flagellin synthesis and phospholipase secretion, similar to naturally occurring BT2 strains. Transcriptome analysis confirmed flhDC regulation of flagellar, chemotaxis and phospholipase loci as well as other genes of diverse function. The flhD mutation confers a competitive advantage within the fish host when compared with its parent strain, while this advantage was not seen with the naturally occurring fliR mutation. An intact flhD is necessary for expression of the flagellar secretion system as well as other diverse loci, consistent with a role for flhD as a pleiotropic regulator. The maintenance of the flhD locus in Y. ruckeri strains suggests its importance for aspects of Y. ruckeri biology other than virulence, since the flhD mutation conferred a competitive advantage during experimental challenge of rainbow trout. Yersinia ruckeri is the causative agent of enteric red mouth disease, an invasive septicaemia that affects farmed salmonid fish species. Disease outbreaks can cause severe economic losses in aquaculture. BT2 variants, which have independently emerged worldwide, are an increasing threat to farmed fish production. Knowledge of mechanisms involved in virulence, conserved functions and gene regulation among strains may be exploited for the development of novel disease control strategies to prevent pathogen growth or virulence phenotypes within aquaculture. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Pseudomonas aeruginosa flagellar motility activates the phagocyte PI3K/Akt pathway to induce phagocytic engulfment.

PubMed

Lovewell, Rustin R; Hayes, Sandra M; O'Toole, George A; Berwin, Brent

2014-04-01

Phagocytosis of the bacterial pathogen Pseudomonas aeruginosa is the primary means by which the host controls bacterially induced pneumonia during lung infection. Previous studies have identified flagellar swimming motility as a key pathogen-associated molecular pattern (PAMP) recognized by phagocytes to initiate engulfment. Correspondingly, loss of flagellar motility is observed during chronic pulmonary infection with P. aeruginosa, and this likely reflects a selection for bacteria resistant to phagocytic clearance. However, the mechanism underlying the preferential phagocytic response to motile bacteria is unknown. Here we have identified a cellular signaling pathway in alveolar macrophages and other phagocytes that is specifically activated by flagellar motility. Genetic and biochemical methods were employed to identify that phagocyte PI3K/Akt activation is required for bacterial uptake and, importantly, it is specifically activated in response to P. aeruginosa flagellar motility. Based on these observations, the second important finding that emerged from these studies is that titration of the bacterial flagellar motility results in a proportional activation state of Akt. Therefore, the Akt pathway is responsive to, and corresponds with, the degree of bacterial flagellar motility, is independent of the actin polymerization that facilitates phagocytosis, and determines the phagocytic fate of P. aeruginosa. These findings elucidate the mechanism behind motility-dependent phagocytosis of extracellular bacteria and support a model whereby phagocytic clearance exerts a selective pressure on P. aeruginosa populations in vivo, which contributes to changes in pathogenesis during infections.

Pseudomonas aeruginosa flagellar motility activates the phagocyte PI3K/Akt pathway to induce phagocytic engulfment

PubMed Central

Lovewell, Rustin R.; Hayes, Sandra M.; O'Toole, George A.

2014-01-01

Phagocytosis of the bacterial pathogen Pseudomonas aeruginosa is the primary means by which the host controls bacterially induced pneumonia during lung infection. Previous studies have identified flagellar swimming motility as a key pathogen-associated molecular pattern (PAMP) recognized by phagocytes to initiate engulfment. Correspondingly, loss of flagellar motility is observed during chronic pulmonary infection with P. aeruginosa, and this likely reflects a selection for bacteria resistant to phagocytic clearance. However, the mechanism underlying the preferential phagocytic response to motile bacteria is unknown. Here we have identified a cellular signaling pathway in alveolar macrophages and other phagocytes that is specifically activated by flagellar motility. Genetic and biochemical methods were employed to identify that phagocyte PI3K/Akt activation is required for bacterial uptake and, importantly, it is specifically activated in response to P. aeruginosa flagellar motility. Based on these observations, the second important finding that emerged from these studies is that titration of the bacterial flagellar motility results in a proportional activation state of Akt. Therefore, the Akt pathway is responsive to, and corresponds with, the degree of bacterial flagellar motility, is independent of the actin polymerization that facilitates phagocytosis, and determines the phagocytic fate of P. aeruginosa. These findings elucidate the mechanism behind motility-dependent phagocytosis of extracellular bacteria and support a model whereby phagocytic clearance exerts a selective pressure on P. aeruginosa populations in vivo, which contributes to changes in pathogenesis during infections. PMID:24487390

Flagellar flows around bacterial swarms

NASA Astrophysics Data System (ADS)

Dauparas, Justas; Lauga, Eric

2016-08-01

Flagellated bacteria on nutrient-rich substrates can differentiate into a swarming state and move in dense swarms across surfaces. A recent experiment measured the flow in the fluid around an Escherichia coli swarm [Wu, Hosu, and Berg, Proc. Natl. Acad. Sci. USA 108, 4147 (2011)], 10.1073/pnas.1016693108. A systematic chiral flow was observed in the clockwise direction (when viewed from above) ahead of the swarm with flow speeds of about 10 μ m /s , about 3 times greater than the radial velocity at the edge of the swarm. The working hypothesis is that this flow is due to the action of cells stalled at the edge of a colony that extend their flagellar filaments outward, moving fluid over the virgin agar. In this work we quantitatively test this hypothesis. We first build an analytical model of the flow induced by a single flagellum in a thin film and then use the model, and its extension to multiple flagella, to compare with experimental measurements. The results we obtain are in agreement with the flagellar hypothesis. The model provides further quantitative insight into the flagella orientations and their spatial distributions as well as the tangential speed profile. In particular, the model suggests that flagella are on average pointing radially out of the swarm and are not wrapped tangentially.

Changes in the flagellar bundling time account for variations in swimming behavior of flagellated bacteria in viscous media

NASA Astrophysics Data System (ADS)

Qu, Zijie; Temel, Fatma; Henderikx, Rene; Breuer, Kenneth

2017-11-01

The motility of bacteria E.coli in viscous fluids has been widely studied, although conflicting results on the effect of viscosity on swimming speed abound. The swimming mode of wild-type E.coli is idealized as a run-and-tumble sequence in which periods of straight swimming at a constant speed are randomly interrupted by a tumble, defined as a sudden change of direction with a very low speed. Using a tracking microscope, we follow cells for extended time and find that the swimming behavior of a single cell can exhibit a variety of behaviors including run-and-tumble and ``slow-random-walk'' in which the cells move at relatively low speed without the characteristic run. Although the characteristic swimming speed varies between individuals and in different polymer solutions, we find that the skewness of the speed distribution is solely a function of viscosity, and uniquely determines the ratio of the average speed to the characteristic run speed. Using Resistive Force Theory and the cell-specific measured characteristic run speed, we show that differences in the swimming behavior observed in solutions of different viscosity are due to changes in the flagellar bundling time, which increases as the viscosity rises, due to lower rotation rate of the flagellar motor. National Science Foundation.

Calaxin drives sperm chemotaxis by Ca2+-mediated direct modulation of a dynein motor

PubMed Central

Mizuno, Katsutoshi; Shiba, Kogiku; Okai, Masahiko; Takahashi, Yusuke; Shitaka, Yuji; Oiwa, Kazuhiro; Tanokura, Masaru; Inaba, Kazuo

2012-01-01

Sperm chemotaxis occurs widely in animals and plants and plays an important role in the success of fertilization. Several studies have recently demonstrated that Ca2+ influx through specific Ca2+ channels is a prerequisite for sperm chemotactic movement. However, the regulator that modulates flagellar movement in response to Ca2+ is unknown. Here we show that a neuronal calcium sensor, calaxin, directly acts on outer-arm dynein and regulates specific flagellar movement during sperm chemotaxis. Calaxin inhibition resulted in significant loss of sperm chemotactic movement, despite normal increases in intracellular calcium concentration. Using a demembranated sperm model, we demonstrate that calaxin is essential for generation and propagation of Ca2+-induced asymmetric flagellar bending. An in vitro motility assay revealed that calaxin directly suppressed the velocity of microtubule sliding by outer-arm dynein at high Ca2+ concentrations. This study describes the missing link between chemoattractant-mediated Ca2+ signaling and motor-driven microtubule sliding during sperm chemotaxis. PMID:23169663

Control of Flagellar Gene Regulation in Legionella pneumophila and Its Relation to Growth Phase▿ †

PubMed Central

Albert-Weissenberger, Christiane; Sahr, Tobias; Sismeiro, Odile; Hacker, Jörg; Heuner, Klaus; Buchrieser, Carmen

2010-01-01

The bacterial pathogen Legionella pneumophila responds to environmental changes by differentiation. At least two forms are well described: replicative bacteria are avirulent; in contrast, transmissive bacteria express virulence traits and flagella. Phenotypic analysis, Western blotting, and electron microscopy of mutants of the regulatory genes encoding RpoN, FleQ, FleR, and FliA demonstrated that flagellin expression is strongly repressed and that the mutants are nonflagellated in the transmissive phase. Transcriptome analyses elucidated that RpoN, together with FleQ, enhances transcription of 14 out of 31 flagellar class II genes, which code for the basal body, hook, and regulatory proteins. Unexpectedly, FleQ independent of RpoN enhances the transcription of fliA encoding sigma 28. Expression analysis of a fliA mutant showed that FliA activates three out of the five remaining flagellar class III genes and the flagellar class IV genes. Surprisingly, FleR does not induce but inhibits expression of at least 14 flagellar class III genes on the transcriptional level. Thus, we propose that flagellar class II genes are controlled by FleQ and RpoN, whereas the transcription of the class III gene fliA is controlled in a FleQ-dependent but RpoN-independent manner. However, RpoN and FleR might influence flagellin synthesis on a posttranscriptional level. In contrast to the commonly accepted view that enhancer-binding proteins such as FleQ always interact with RpoN to fullfill their regulatory functions, our results strongly indicate that FleQ regulates gene expression that is RpoN dependent and RpoN independent. Finally, FliA induces expression of flagellar class III and IV genes leading to the complete synthesis of the flagellum. PMID:19915024

Bacterial flagellar capping proteins adopt diverse oligomeric states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Postel, Sandra; Deredge, Daniel; Bonsor, Daniel A.

2016-09-24

Flagella are crucial for bacterial motility and pathogenesis. The flagellar capping protein (FliD) regulates filament assembly by chaperoning and sorting flagellin (FliC) proteins after they traverse the hollow filament and exit the growing flagellum tip. In the absence of FliD, flagella are not formed, resulting in impaired motility and infectivity. Here, we report the 2.2 Å resolution X-ray crystal structure of FliD fromPseudomonas aeruginosa, the first high-resolution structure of any FliD protein from any bacterium. Using this evidence in combination with a multitude of biophysical and functional analyses, we find thatPseudomonasFliD exhibits unexpected structural similarity to other flagellar proteins atmore » the domain level, adopts a unique hexameric oligomeric state, and depends on flexible determinants for oligomerization. Considering that the flagellin filaments on which FliD oligomers are affixed vary in protofilament number between bacteria, our results suggest that FliD oligomer stoichiometries vary across bacteria to complement their filament assemblies.« less

Genome-wide transcriptional analysis of flagellar regeneration in Chlamydomonas reinhardtii identifies orthologs of ciliary disease genes

NASA Technical Reports Server (NTRS)

Stolc, Viktor; Samanta, Manoj Pratim; Tongprasit, Waraporn; Marshall, Wallace F.

2005-01-01

The important role that cilia and flagella play in human disease creates an urgent need to identify genes involved in ciliary assembly and function. The strong and specific induction of flagellar-coding genes during flagellar regeneration in Chlamydomonas reinhardtii suggests that transcriptional profiling of such cells would reveal new flagella-related genes. We have conducted a genome-wide analysis of RNA transcript levels during flagellar regeneration in Chlamydomonas by using maskless photolithography method-produced DNA oligonucleotide microarrays with unique probe sequences for all exons of the 19,803 predicted genes. This analysis represents previously uncharacterized whole-genome transcriptional activity profiling study in this important model organism. Analysis of strongly induced genes reveals a large set of known flagellar components and also identifies a number of important disease-related proteins as being involved with cilia and flagella, including the zebrafish polycystic kidney genes Qilin, Reptin, and Pontin, as well as the testis-expressed tubby-like protein TULP2.

Viscous Dynamics of Lyme Disease and Syphilis Spirochetes Reveal Flagellar Torque and Drag

PubMed Central

Harman, Michael; Vig, Dhruv K.; Radolf, Justin D.; Wolgemuth, Charles W.

2013-01-01

The spirochetes that cause Lyme disease (Borrelia burgdorferi) and syphilis (Treponema pallidum) swim through viscous fluids, such as blood and interstitial fluid, by undulating their bodies as traveling, planar waves. These undulations are driven by rotation of the flagella within the periplasmic space, the narrow (∼20–40 nm in width) compartment between the inner and outer membranes. We show here that the swimming speeds of B. burgdorferi and T. pallidum decrease with increases in viscosity of the external aqueous milieu, even though the flagella are entirely intracellular. We then use mathematical modeling to show that the measured changes in speed are consistent with the exertion of constant torque by the spirochetal flagellar motors. Comparison of simulations, experiments, and a simple model for power dissipation allows us to estimate the torque and resistive drag that act on the flagella of these major spirochetal pathogens. PMID:24268139

The Bacterial Flagellar Type III Export Gate Complex Is a Dual Fuel Engine That Can Use Both H+ and Na+ for Flagellar Protein Export

PubMed Central

Minamino, Tohru; Morimoto, Yusuke V.; Hara, Noritaka; Aldridge, Phillip D.; Namba, Keiichi

2016-01-01

The bacterial flagellar type III export apparatus utilizes ATP and proton motive force (PMF) to transport flagellar proteins to the distal end of the growing flagellar structure for self-assembly. The transmembrane export gate complex is a H+–protein antiporter, of which activity is greatly augmented by an associated cytoplasmic ATPase complex. Here, we report that the export gate complex can use sodium motive force (SMF) in addition to PMF across the cytoplasmic membrane to drive protein export. Protein export was considerably reduced in the absence of the ATPase complex and a pH gradient across the membrane, but Na+ increased it dramatically. Phenamil, a blocker of Na+ translocation, inhibited protein export. Overexpression of FlhA increased the intracellular Na+ concentration in the presence of 100 mM NaCl but not in its absence, suggesting that FlhA acts as a Na+ channel. In wild-type cells, however, neither Na+ nor phenamil affected protein export, indicating that the Na+ channel activity of FlhA is suppressed by the ATPase complex. We propose that the export gate by itself is a dual fuel engine that uses both PMF and SMF for protein export and that the ATPase complex switches this dual fuel engine into a PMF-driven export machinery to become much more robust against environmental changes in external pH and Na+ concentration. PMID:26943926

The Bacterial Flagellar Type III Export Gate Complex Is a Dual Fuel Engine That Can Use Both H+ and Na+ for Flagellar Protein Export.

PubMed

Minamino, Tohru; Morimoto, Yusuke V; Hara, Noritaka; Aldridge, Phillip D; Namba, Keiichi

2016-03-01

The bacterial flagellar type III export apparatus utilizes ATP and proton motive force (PMF) to transport flagellar proteins to the distal end of the growing flagellar structure for self-assembly. The transmembrane export gate complex is a H+-protein antiporter, of which activity is greatly augmented by an associated cytoplasmic ATPase complex. Here, we report that the export gate complex can use sodium motive force (SMF) in addition to PMF across the cytoplasmic membrane to drive protein export. Protein export was considerably reduced in the absence of the ATPase complex and a pH gradient across the membrane, but Na+ increased it dramatically. Phenamil, a blocker of Na+ translocation, inhibited protein export. Overexpression of FlhA increased the intracellular Na+ concentration in the presence of 100 mM NaCl but not in its absence, suggesting that FlhA acts as a Na+ channel. In wild-type cells, however, neither Na+ nor phenamil affected protein export, indicating that the Na+ channel activity of FlhA is suppressed by the ATPase complex. We propose that the export gate by itself is a dual fuel engine that uses both PMF and SMF for protein export and that the ATPase complex switches this dual fuel engine into a PMF-driven export machinery to become much more robust against environmental changes in external pH and Na+ concentration.

KHARON Is an Essential Cytoskeletal Protein Involved in the Trafficking of Flagellar Membrane Proteins and Cell Division in African Trypanosomes*

PubMed Central

Sanchez, Marco A.; Tran, Khoa D.; Valli, Jessica; Hobbs, Sam; Johnson, Errin; Gluenz, Eva; Landfear, Scott M.

2016-01-01

African trypanosomes and related kinetoplastid parasites selectively traffic specific membrane proteins to the flagellar membrane, but the mechanisms for this trafficking are poorly understood. We show here that KHARON, a protein originally identified in Leishmania parasites, interacts with a putative trypanosome calcium channel and is required for its targeting to the flagellar membrane. KHARON is located at the base of the flagellar axoneme, where it likely mediates targeting of flagellar membrane proteins, but is also on the subpellicular microtubules and the mitotic spindle. Hence, KHARON is probably a multifunctional protein that associates with several components of the trypanosome cytoskeleton. RNA interference-mediated knockdown of KHARON mRNA results in failure of the calcium channel to enter the flagellar membrane, detachment of the flagellum from the cell body, and disruption of mitotic spindles. Furthermore, knockdown of KHARON mRNA induces a lethal failure of cytokinesis in both bloodstream (mammalian host) and procyclic (insect vector) life cycle stages, and KHARON is thus critical for parasite viability. PMID:27489106

An Ultrasensitive Bacterial Motor Revealed by Monitoring Signaling Proteins in Single Cells

NASA Astrophysics Data System (ADS)

Cluzel, Philippe; Surette, Michael; Leibler, Stanislas

2000-03-01

Understanding biology at the single-cell level requires simultaneous measurements of biochemical parameters and behavioral characteristics in individual cells. Here, the output of individual flagellar motors in Escherichia coli was measured as a function of the intracellular concentration of the chemotactic signaling protein. The concentration of this molecule, fused to green fluorescent protein, was monitored with fluorescence correlation spectroscopy. Motors from different bacteria exhibited an identical steep input-output relation, suggesting that they actively contribute to signal amplification in chemotaxis. This experimental approach can be extended to quantitative in vivo studies of other biochemical networks.

MotD of Sinorhizobium meliloti and Related α-Proteobacteria Is the Flagellar-Hook-Length Regulator and Therefore Reassigned as FliK

PubMed Central

Eggenhofer, Elke; Rachel, Reinhard; Haslbeck, Martin; Scharf, Birgit

2006-01-01

The flagella of the soil bacterium Sinorhizobium meliloti differ from the enterobacterial paradigm in the complex filament structure and modulation of the flagellar rotary speed. The mode of motility control in S. meliloti has a molecular corollary in two novel periplasmic motility proteins, MotC and MotE, that are present in addition to the ubiquitous MotA/MotB energizing proton channel. A fifth motility gene is located in the mot operon downstream of the motB and motC genes. Its gene product was originally designated MotD, a cytoplasmic motility protein having an unknown function. We report here reassignment of MotD as FliK, the regulator of flagellar hook length. The FliK gene is one of the few flagellar genes not annotated in the contiguous flagellar regulon of S. meliloti. Characteristic for its class, the 475-residue FliK protein contains a conserved, compactly folded Flg hook domain in its carboxy-terminal region. Deletion of fliK leads to formation of prolonged flagellar hooks (polyhooks) with missing filament structures. Extragenic suppressor mutations all mapped in the cytoplasmic region of the transmembrane export protein FlhB and restored assembly of a flagellar filament, and thus motility, in the presence of polyhooks. The structural properties of FliK are consistent with its function as a substrate specificity switch of the flagellar export apparatus for switching from rod/hook-type substrates to filament-type substrates. PMID:16513744

Crystallographic and Molecular Dynamics Analysis of Loop Motions Unmasking the Peptidoglycan-Binding Site in Stator Protein MotB of Flagellar Motor

PubMed Central

Nahar, Musammat F.; Buckle, Ashley M.; Roujeinikova, Anna

2011-01-01

Background The C-terminal domain of MotB (MotB-C) shows high sequence similarity to outer membrane protein A and related peptidoglycan (PG)-binding proteins. It is believed to anchor the power-generating MotA/MotB stator unit of the bacterial flagellar motor to the peptidoglycan layer of the cell wall. We previously reported the first crystal structure of this domain and made a puzzling observation that all conserved residues that are thought to be essential for PG recognition are buried and inaccessible in the crystal structure. In this study, we tested a hypothesis that peptidoglycan binding is preceded by, or accompanied by, some structural reorganization that exposes the key conserved residues. Methodology/Principal Findings We determined the structure of a new crystalline form (Form B) of Helicobacter pylori MotB-C. Comparisons with the existing Form A revealed conformational variations in the petal-like loops around the carbohydrate binding site near one end of the β-sheet. These variations are thought to reflect natural flexibility at this site required for insertion into the peptidoglycan mesh. In order to understand the nature of this flexibility we have performed molecular dynamics simulations of the MotB-C dimer. The results are consistent with the crystallographic data and provide evidence that the three loops move in a concerted fashion, exposing conserved MotB residues that have previously been implicated in binding of the peptide moiety of peptidoglycan. Conclusion/Significance Our structural analysis provides a new insight into the mechanism by which MotB inserts into the peptidoglycan mesh, thus anchoring the power-generating complex to the cell wall. PMID:21533052

Structure of Salmonella FlhE, conserved member of a flagellar Type III secretion operon

DOE PAGES

Lee, Jaemin; Monzingo, Arthur F.; Keatinge-Clay, Adrian T.; ...

2014-12-26

In this paper, the bacterial flagellum is assembled by a multicomponent transport apparatus categorized as a type III secretion system. The secretion of proteins that assemble into the flagellum is driven by the proton motive force. The periplasmic protein FlhE is a member of the flhBAE operon in the majority of bacteria where FlhE is found. FlhA and FlhB are established components of the flagellar type III secretion system. The absence of FlhE results in a proton leak through the flagellar system, inappropriate secretion patterns, and cell death, indicating that FlhE regulates an important aspect of proper flagellar biosynthesis. Wemore » isolated FlhE from the periplasm of Salmonella and solved its structure to 1.5 Å resolution. The structure reveals a β-sandwich fold, with no close structural homologs. Finally, possible roles of FlhE, including that of a chaperone, are discussed.« less

Structure of Salmonella FlhE, conserved member of a flagellar Type III secretion operon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Jaemin; Monzingo, Arthur F.; Keatinge-Clay, Adrian T.

In this paper, the bacterial flagellum is assembled by a multicomponent transport apparatus categorized as a type III secretion system. The secretion of proteins that assemble into the flagellum is driven by the proton motive force. The periplasmic protein FlhE is a member of the flhBAE operon in the majority of bacteria where FlhE is found. FlhA and FlhB are established components of the flagellar type III secretion system. The absence of FlhE results in a proton leak through the flagellar system, inappropriate secretion patterns, and cell death, indicating that FlhE regulates an important aspect of proper flagellar biosynthesis. Wemore » isolated FlhE from the periplasm of Salmonella and solved its structure to 1.5 Å resolution. The structure reveals a β-sandwich fold, with no close structural homologs. Finally, possible roles of FlhE, including that of a chaperone, are discussed.« less

Somatosensory responses in a human motor cortex

PubMed Central

Donoghue, John P.; Hochberg, Leigh R.

2013-01-01

Somatic sensory signals provide a major source of feedback to motor cortex. Changes in somatosensory systems after stroke or injury could profoundly influence brain computer interfaces (BCI) being developed to create new output signals from motor cortex activity patterns. We had the unique opportunity to study the responses of hand/arm area neurons in primary motor cortex to passive joint manipulation in a person with a long-standing brain stem stroke but intact sensory pathways. Neurons responded to passive manipulation of the contralateral shoulder, elbow, or wrist as predicted from prior studies of intact primates. Thus fundamental properties and organization were preserved despite arm/hand paralysis and damage to cortical outputs. The same neurons were engaged by attempted arm actions. These results indicate that intact sensory pathways retain the potential to influence primary motor cortex firing rates years after cortical outputs are interrupted and may contribute to online decoding of motor intentions for BCI applications. PMID:23343902

Human sperm steer with second harmonics of the flagellar beat.

PubMed

Saggiorato, Guglielmo; Alvarez, Luis; Jikeli, Jan F; Kaupp, U Benjamin; Gompper, Gerhard; Elgeti, Jens

2017-11-10

Sperm are propelled by bending waves traveling along their flagellum. For steering in gradients of sensory cues, sperm adjust the flagellar waveform. Symmetric and asymmetric waveforms result in straight and curved swimming paths, respectively. Two mechanisms causing spatially asymmetric waveforms have been proposed: an average flagellar curvature and buckling. We image flagella of human sperm tethered with the head to a surface. The waveform is characterized by a fundamental beat frequency and its second harmonic. The superposition of harmonics breaks the beat symmetry temporally rather than spatially. As a result, sperm rotate around the tethering point. The rotation velocity is determined by the second-harmonic amplitude and phase. Stimulation with the female sex hormone progesterone enhances the second-harmonic contribution and, thereby, modulates sperm rotation. Higher beat frequency components exist in other flagellated cells; therefore, this steering mechanism might be widespread and could inspire the design of synthetic microswimmers.

Flagellar central pair assembly in Chlamydomonas reinhardtii

PubMed Central

2013-01-01

Background Most motile cilia and flagella have nine outer doublet and two central pair (CP) microtubules. Outer doublet microtubules are continuous with the triplet microtubules of the basal body, are templated by the basal body microtubules, and grow by addition of new subunits to their distal (“plus”) ends. In contrast, CP microtubules are not continuous with basal body microtubules, raising the question of how these microtubules are assembled and how their polarity is established. Methods CP assembly in Chlamydomonas reinhardtii was analyzed by electron microscopy and wide-field and super-resolution immunofluorescence microscopy. To analyze CP assembly independently from flagellar assembly, the CP-deficient katanin mutants pf15 or pf19 were mated to wild-type cells. HA-tagged tubulin and the CP-specific protein hydin were used as markers to analyze de novo CP assembly inside the formerly mutant flagella. Results In regenerating flagella, the CP and its projections assemble near the transition zone soon after the onset of outer doublet elongation. During de novo CP assembly in full-length flagella, the nascent CP was first apparent in a subdistal region of the flagellum. The developing CP replaces a fibrous core that fills the axonemal lumen of CP-deficient flagella. The fibrous core contains proteins normally associated with the C1 CP microtubule and proteins involved in intraflagellar transport (IFT). In flagella of the radial spoke-deficient mutant pf14, two pairs of CPs are frequently present with identical correct polarities. Conclusions The temporal separation of flagellar and CP assembly in dikaryons formed by mating CP-deficient gametes to wild-type gametes revealed that the formation of the CP does not require proximity to the basal body or transition zone, or to the flagellar tip. The observations on pf14 provide further support that the CP self-assembles without a template and eliminate the possibility that CP polarity is established by interaction

Two flagellar BAR domain proteins in Trypanosoma brucei with stage-specific regulation

PubMed Central

Cicova, Zdenka; Dejung, Mario; Skalicky, Tomas; Eisenhuth, Nicole; Hanselmann, Steffen; Morriswood, Brooke; Figueiredo, Luisa M.; Butter, Falk; Janzen, Christian J.

2016-01-01

Trypanosomes are masters of adaptation to different host environments during their complex life cycle. Large-scale proteomic approaches provide information on changes at the cellular level, and in a systematic way. However, detailed work on single components is necessary to understand the adaptation mechanisms on a molecular level. Here, we have performed a detailed characterization of a bloodstream form (BSF) stage-specific putative flagellar host adaptation factor Tb927.11.2400, identified previously in a SILAC-based comparative proteome study. Tb927.11.2400 shares 38% amino acid identity with TbFlabarin (Tb927.11.2410), a procyclic form (PCF) stage-specific flagellar BAR domain protein. We named Tb927.11.2400 TbFlabarin-like (TbFlabarinL), and demonstrate that it originates from a gene duplication event, which occurred in the African trypanosomes. TbFlabarinL is not essential for the growth of the parasites under cell culture conditions and it is dispensable for developmental differentiation from BSF to the PCF in vitro. We generated TbFlabarinL-specific antibodies, and showed that it localizes in the flagellum. Co-immunoprecipitation experiments together with a biochemical cell fractionation suggest a dual association of TbFlabarinL with the flagellar membrane and the components of the paraflagellar rod. PMID:27779220

Genetic dissection of the consensus sequence for the class 2 and class 3 flagellar promoters

PubMed Central

Wozniak, Christopher E.; Hughes, Kelly T.

2008-01-01

Summary Computational searches for DNA binding sites often utilize consensus sequences. These search models make assumptions that the frequency of a base pair in an alignment relates to the base pair’s importance in binding and presume that base pairs contribute independently to the overall interaction with the DNA binding protein. These two assumptions have generally been found to be accurate for DNA binding sites. However, these assumptions are often not satisfied for promoters, which are involved in additional steps in transcription initiation after RNA polymerase has bound to the DNA. To test these assumptions for the flagellar regulatory hierarchy, class 2 and class 3 flagellar promoters were randomly mutagenized in Salmonella. Important positions were then saturated for mutagenesis and compared to scores calculated from the consensus sequence. Double mutants were constructed to determine how mutations combined for each promoter type. Mutations in the binding site for FlhD4C2, the activator of class 2 promoters, better satisfied the assumptions for the binding model than did mutations in the class 3 promoter, which is recognized by the σ28 transcription factor. These in vivo results indicate that the activator sites within flagellar promoters can be modeled using simple assumptions but that the DNA sequences recognized by the flagellar sigma factor require more complex models. PMID:18486950

Modulation of Chlamydomonas reinhardtii flagellar motility by redox poise

PubMed Central

Wakabayashi, Ken-ichi; King, Stephen M.

2006-01-01

Redox-based regulatory systems are essential for many cellular activities. Chlamydomonas reinhardtii exhibits alterations in motile behavior in response to different light conditions (photokinesis). We hypothesized that photokinesis is signaled by variations in cytoplasmic redox poise resulting from changes in chloroplast activity. We found that this effect requires photosystem I, which generates reduced NADPH. We also observed that photokinetic changes in beat frequency and duration of the photophobic response could be obtained by altering oxidative/reductive stress. Analysis of reactivated cell models revealed that this redox poise effect is mediated through the outer dynein arms (ODAs). Although the global redox state of the thioredoxin-related ODA light chains LC3 and LC5 and the redox-sensitive Ca2+-binding subunit of the docking complex DC3 did not change upon light/dark transitions, we did observe significant alterations in their interactions with other flagellar components via mixed disulfides. These data indicate that redox poise directly affects ODAs and suggest that it may act in the control of flagellar motility. PMID:16754958

The flagellar apparatus of heteroloboseans.

PubMed

Brugerolle, Guy; Simpson, Alastair G B

2004-01-01

The flagellar apparatus of four heterolobosean species Percolomonas descissus, Percolomonas sulcatus, Tetramitus rostratus, and Naegleria gruberi were examined. P. descissus lives in oxygen-poor water. It is a quadriflagellated cell with a ventral groove. The two pairs of basal bodies are connected to an apical structure from which the peripheral dorso-lateral microtubules and a short striated rhizoplast originate. There is one major microtubular root, R1, which originates from the posterior basal body pair and splits into left and right portions that support the sides of the ventral groove. The anterior pair of basal bodies is associated with a root of four to five microtubules that runs to the left of the groove. This organisation is similar to that previously reported for Psalteriomonas, Lyromonas, and Percolomonas cosmopolitus. Percolomonas sulcatus has two parallel pairs of basal bodies, each of which is associated with a well-developed R1 root. These roots divide to give two distinct left portions and one merged right portion that support the margins of the slit-like ventral groove. Tetramitus rostratus has two pairs of basal bodies, several rhizoplast fibres, and two R1 roots. Each R1 root supports one wall of the ventral groove. Naegleria gruberi may have two pairs of basal bodies, each associated with a microtubular root and one long rhizoplast fibre. From available data, a 'double bikont'-like organisation of the heterolobosean flagellar apparatus is inferred, where both of the eldest basal bodies have largely 'mature' complements of microtubular roots. The cytoskeletal organisation of heteroloboseans is compared to those of (other) excavates. Our structural data and existing molecular phylogenies weaken the case that Percolomonas, Psalteriomonas, and Lyromonas are phylogenetically separable from other heteroloboseans, undermining many of the highest-level taxa proposed for these organisms, including Percolozoa, Striatorhiza, Percolomonada, Percolomonadea

FliH and FliI ensure efficient energy coupling of flagellar type III protein export in Salmonella.

PubMed

Minamino, Tohru; Kinoshita, Miki; Inoue, Yumi; Morimoto, Yusuke V; Ihara, Kunio; Koya, Satomi; Hara, Noritaka; Nishioka, Noriko; Kojima, Seiji; Homma, Michio; Namba, Keiichi

2016-06-01

For construction of the bacterial flagellum, flagellar proteins are exported via its specific export apparatus from the cytoplasm to the distal end of the growing flagellar structure. The flagellar export apparatus consists of a transmembrane (TM) export gate complex and a cytoplasmic ATPase complex consisting of FliH, FliI, and FliJ. FlhA is a TM export gate protein and plays important roles in energy coupling of protein translocation. However, the energy coupling mechanism remains unknown. Here, we performed a cross-complementation assay to measure robustness of the energy transduction system of the export apparatus against genetic perturbations. Vibrio FlhA restored motility of a Salmonella ΔflhA mutant but not that of a ΔfliH-fliI flhB(P28T) ΔflhA mutant. The flgM mutations significantly increased flagellar gene expression levels, allowing Vibrio FlhA to exert its export activity in the ΔfliH-fliI flhB(P28T) ΔflhA mutant. Pull-down assays revealed that the binding affinities of Vibrio FlhA for FliJ and the FlgN-FlgK chaperone-substrate complex were much lower than those of Salmonella FlhA. These suggest that Vibrio FlhA requires the support of FliH and FliI to efficiently and properly interact with FliJ and the FlgN-FlgK complex. We propose that FliH and FliI ensure robust and efficient energy coupling of protein export during flagellar assembly. © 2016 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

The counterbend phenomenon in flagellar axonemes and cross-linked filament bundles

PubMed Central

Gadêlha, Hermes; Gaffney, Eamonn A.; Goriely, Alain

2013-01-01

Recent observations of flagellar counterbend in sea urchin sperm show that the mechanical induction of curvature in one part of a passive flagellum induces a compensatory countercurvature elsewhere. This apparent paradoxical effect cannot be explained using the standard elastic rod theory of Euler and Bernoulli, or even the more general Cosserat theory of rods. Here, we develop a geometrically exact mechanical model to describe the statics of microtubule bundles that is capable of predicting the curvature reversal events observed in eukaryotic flagella. This is achieved by allowing the interaction of deformations in different material directions, by accounting not only for structural bending, but also for the elastic forces originating from the internal cross-linking mechanics. Large-amplitude static configurations can be described analytically, and an excellent match between the model and the observed counterbend deformation was found. This allowed a simultaneous estimation of multiple sperm flagellum material parameters, namely the cross-linking sliding resistance, the bending stiffness, and the sperm head junction compliance ratio. We further show that small variations on the empirical conditions may induce discrepancies for the evaluation of the flagellar material quantities, so that caution is required when interpreting experiments. Finally, our analysis demonstrates that the counterbend emerges as a fundamental property of sliding resistance in cross-linked filamentous polymer bundles, which also suggests that cross-linking proteins may contribute to the regulation of the flagellar waveform in swimming sperm via counterbend mechanics. PMID:23824293

A chemotactic signaling surface on CheY defined by suppressors of flagellar switch mutations.

PubMed Central

Roman, S J; Meyers, M; Volz, K; Matsumura, P

1992-01-01

CheY is the response regulator protein that interacts with the flagellar switch apparatus to modulate flagellar rotation during chemotactic signaling. CheY can be phosphorylated and dephosphorylated in vitro, and evidence indicates that CheY-P is the activated form that induces clockwise flagellar rotation, resulting in a tumble in the cell's swimming pattern. The flagellar switch apparatus is a complex macromolecular structure composed of at least three gene products, FliG, FliM, and FliN. Genetic analysis of Escherichia coli has identified fliG and fliM as genes in which mutations occur that allele specifically suppress cheY mutations, indicating interactions among these gene products. We have generated a class of cheY mutations selected for dominant suppression of fliG mutations. Interestingly, these cheY mutations dominantly suppressed both fliG and fliM mutations; this is consistent with the idea that the CheY protein interacts with both switch gene products during signaling. Biochemical characterization of wild-type and suppressor CheY proteins did not reveal altered phosphorylation properties or evidence for phosphorylation-dependent CheY multimerization. These data indicate that suppressor CheY proteins are specifically altered in the ability to transduce chemotactic signals to the switch at some point subsequent to phosphorylation. Physical mapping of suppressor amino acid substitutions on the crystal structure of CheY revealed a high degree of spatial clustering, suggesting that this region of CheY is a signaling surface that transduces chemotactic signals to the switch. Images PMID:1400175

Effective viscosity of a suspension of flagellar-beating microswimmers: Three-dimensional modeling

NASA Astrophysics Data System (ADS)

Jibuti, Levan; Zimmermann, Walter; Rafaï, Salima; Peyla, Philippe

2017-11-01

Micro-organisms usually can swim in their liquid environment by flagellar or ciliary beating. In this numerical work, we analyze the influence of flagellar beating on the orbits of a swimming cell in a shear flow. We also calculate the effect of the flagellar beating on the rheology of a dilute suspension of microswimmers. A three-dimensional model is proposed for Chlamydomonas Reinhardtii swimming with a breaststroke-like beating of two anterior flagella modeled by two counter-rotating fore beads. The active swimmer model reveals unusual angular orbits in a linear shear flow. Namely, the swimmer sustains orientations transiently across the flow. Such behavior is a result of the interplay between shear flow and the swimmer's periodic beating motion of flagella, which exert internal torques on the cell body. This peculiar behavior has some significant consequences on the rheological properties of the suspension. We calculate Einstein's viscosity of the suspension composed of such isolated modeled microswimmers (dilute case) in a shear flow. We use numerical simulations based on a Rotne-Prager-like approximation for hydrodynamic interaction between simplified flagella and the cell body. The results show an increased intrinsic viscosity for active swimmer suspensions in comparison to nonactive ones as well as a shear thinning behavior in accordance with previous experimental measurements [Phys. Rev. Lett. 104, 098102 (2010), 10.1103/PhysRevLett.104.098102].

Non-genetic individuality in Escherichia coli motor switching

PubMed Central

Mora, Thierry; Bai, Fan; Che, Yong-Suk; Minamino, Tohru; Namba, Keiichi; Wingreen, Ned S.

2011-01-01

By analyzing 30-minute, high-resolution recordings of single E. coli flagellar motors in the physiological regime, we show that two main properties of motor switching —the mean clockwise and mean counter-clockwise interval durations— vary significantly. When we represent these quantities on a two-dimensional plot for several cells, the data does not fall on a one-dimensional curve, as expected with a single control parameter, but instead spreads in two dimensions, pointing to motor individuality. The largest variations are in the mean counter-clockwise interval, and are attributable to variations in the concentration of the internal signaling molecule CheY-P. In contrast, variations in the mean clockwise interval are interpreted in terms of motor individuality. We argue that the sensitivity of the mean counter-clockwise interval to fluctuations in CheY-P is consistent with an optimal strategy of run and tumble. The concomittent variability in mean run length may allow populations of cells to better survive in rapidly changing environments by “hedging their bets”. PMID:21422514

Ion selectivity of the Vibrio alginolyticus flagellar motor.

PubMed Central

Liu, J Z; Dapice, M; Khan, S

1990-01-01

The marine bacterium, Vibrio alginolyticus, normally requires sodium for motility. We found that lithium will substitute for sodium. In neutral pH buffers, the membrane potential and swimming speed of glycolyzing bacteria reached maximal values as sodium or lithium concentration was increased. While the maximal potentials obtained in the two cations were comparable, the maximal swimming speed was substantially lower in lithium. Over a wide range of sodium concentration, the bacteria maintained an invariant sodium electrochemical potential as determined by membrane potential and intracellular sodium measurements. Over this range the increase of swimming speed took Michaelis-Menten form. Artificial energization of swimming motility required imposition of a voltage difference in concert with a sodium pulse. The cation selectivity and concentration dependence exhibited by the motile apparatus depended on the viscosity of the medium. In high-viscosity media, swimming speeds were relatively independent of either ion type or concentration. These facts parallel and extend observations of the swimming behavior of bacteria propelled by proton-powered flagella. In particular, they show that ion transfers limit unloaded motor speed in this bacterium and imply that the coupling between ion transfers and force generation must be fairly tight. PMID:2394685

bop5 mutations reveal new roles for the IC138 phosphoprotein in the regulation of flagellar motility and asymmetric waveforms

PubMed Central

VanderWaal, Kristyn E.; Yamamoto, Ryosuke; Wakabayashi, Ken-ichi; Fox, Laura; Kamiya, Ritsu; Dutcher, Susan K.; Bayly, Phillip V.; Sale, Winfield S.; Porter, Mary E.

2011-01-01

I1 dynein, or dynein f, is a highly conserved inner arm isoform that plays a key role in the regulation of flagellar motility. To understand how the IC138 IC/LC subcomplex modulates I1 activity, we characterized the molecular lesions and motility phenotypes of several bop5 alleles. bop5-3, bop5-4, and bop5-5 are null alleles, whereas bop5-6 is an intron mutation that reduces IC138 expression. I1 dynein assembles into the axoneme, but the IC138 IC/LC subcomplex is missing. bop5 strains, like other I1 mutants, swim forward with reduced swimming velocities and display an impaired reversal response during photoshock. Unlike mutants lacking the entire I1 dynein, however, bop5 strains exhibit normal phototaxis. bop5 defects are rescued by transformation with the wild-type IC138 gene. Analysis of flagellar waveforms reveals that loss of the IC138 subcomplex reduces shear amplitude, sliding velocities, and the speed of bend propagation in vivo, consistent with the reduction in microtubule sliding velocities observed in vitro. The results indicate that the IC138 IC/LC subcomplex is necessary to generate an efficient waveform for optimal motility, but it is not essential for phototaxis. These findings have significant implications for the mechanisms by which IC/LC complexes regulate dynein motor activity independent of effects on cargo binding or complex stability. PMID:21697502

Insight into structural remodeling of the FlhA ring responsible for bacterial flagellar type III protein export

PubMed Central

2018-01-01

The bacterial flagellum is a supramolecular motility machine. Flagellar assembly begins with the basal body, followed by the hook and finally the filament. A carboxyl-terminal cytoplasmic domain of FlhA (FlhAC) forms a nonameric ring structure in the flagellar type III protein export apparatus and coordinates flagellar protein export with assembly. However, the mechanism of this process remains unknown. We report that a flexible linker of FlhAC (FlhAL) is required not only for FlhAC ring formation but also for substrate specificity switching of the protein export apparatus from the hook protein to the filament protein upon completion of the hook structure. FlhAL was required for cooperative ring formation of FlhAC. Alanine substitutions of residues involved in FlhAC ring formation interfered with the substrate specificity switching, thereby inhibiting filament assembly at the hook tip. These observations lead us to propose a mechanistic model for export switching involving structural remodeling of FlhAC. PMID:29707633

How molecular motors work – insights from the molecular machinist's toolbox: the Nobel prize in Chemistry 2016

PubMed Central

Astumian, R. D.

2017-01-01

The Nobel prize in Chemistry for 2016 was awarded to Jean Pierre Sauvage, Sir James Fraser Stoddart, and Bernard (Ben) Feringa for their contributions to the design and synthesis of molecular machines. While this field is still in its infancy, and at present there are no commercial applications, many observers have stressed the tremendous potential of molecular machines to revolutionize technology. However, perhaps the most important result so far accruing from the synthesis of molecular machines is the insight provided into the fundamental mechanisms by which molecular motors, including biological motors such as kinesin, myosin, FoF1 ATPase, and the flagellar motor, function. The ability to “tinker” with separate components of molecular motors allows asking, and answering, specific questions about mechanism, particularly with regard to light driven vs. chemistry driven molecular motors. PMID:28572896

Flagellar filament bio-templated inorganic oxide materials - towards an efficient lithium battery anode

NASA Astrophysics Data System (ADS)

Beznosov, Sergei N.; Veluri, Pavan S.; Pyatibratov, Mikhail G.; Chatterjee, Abhijit; Macfarlane, Douglas R.; Fedorov, Oleg V.; Mitra, Sagar

2015-01-01

Designing a new generation of energy-intensive and sustainable electrode materials for batteries to power a variety of applications is an imperative task. The use of biomaterials as a nanosized structural template for these materials has the potential to produce hitherto unachievable structures. In this report, we have used genetically modified flagellar filaments of the extremely halophilic archaea species Halobacterium salinarum to synthesize nanostructured iron oxide composites for use as a lithium-ion battery anode. The electrode demonstrated a superior electrochemical performance compared to existing literature results, with good capacity retention of 1032 mAh g-1 after 50 cycles and with high rate capability, delivering 770 mAh g-1 at 5 A g-1 (~5 C) discharge rate. This unique flagellar filament based template has the potential to provide access to other highly structured advanced energy materials in the future.

Characterization of a Chlamydomonas Insertional Mutant that Disrupts Flagellar Central Pair Microtubule-associated Structures

PubMed Central

Mitchell, David R.; Sale, Winfield S.

1999-01-01

Two alleles at a new locus, central pair–associated complex 1 (CPC1), were selected in a screen for Chlamydomonas flagellar motility mutations. These mutations disrupt structures associated with central pair microtubules and reduce flagellar beat frequency, but do not prevent changes in flagellar activity associated with either photophobic responses or phototactic accumulation of live cells. Comparison of cpc1 and pf6 axonemes shows that cpc1 affects a row of projections along C1 microtubules distinct from those missing in pf6, and a row of thin fibers that form an arc between the two central pair microtubules. Electron microscopic images of the central pair in axonemes from radial spoke–defective strains reveal previously undescribed central pair structures, including projections extending laterally toward radial spoke heads, and a diagonal link between the C2 microtubule and the cpc1 projection. By SDS-PAGE, cpc1 axonemes show reductions of 350-, 265-, and 79-kD proteins. When extracted from wild-type axonemes, these three proteins cosediment on sucrose gradients with three other central pair proteins (135, 125, and 56 kD) in a 16S complex. Characterization of cpc1 provides new insights into the structure and biochemistry of the central pair apparatus, and into its function as a regulator of dynein-based motility. PMID:9922455

The Armadillo Repeat Protein PF16 Is Essential for Flagellar Structure and Function in Plasmodium Male Gametes

PubMed Central

Ferguson, David J. P.; Bunting, Karen A.; Xu, Zhengyao; Bailes, Elizabeth; Sinden, Robert E.; Holder, Anthony A.; Smith, Elizabeth F.; Coates, Juliet C.; Rita Tewari

2010-01-01

Malaria, caused by the apicomplexan parasite Plasmodium, threatens 40% of the world's population. Transmission between vertebrate and insect hosts depends on the sexual stages of the life-cycle. The male gamete of Plasmodium parasite is the only developmental stage that possesses a flagellum. Very little is known about the identity or function of proteins in the parasite's flagellar biology. Here, we characterise a Plasmodium PF16 homologue using reverse genetics in the mouse malaria parasite Plasmodium berghei. PF16 is a conserved Armadillo-repeat protein that regulates flagellar structure and motility in organisms as diverse as green algae and mice. We show that P. berghei PF16 is expressed in the male gamete flagellum, where it plays a crucial role maintaining the correct microtubule structure in the central apparatus of the axoneme as studied by electron microscopy. Disruption of the PF16 gene results in abnormal flagellar movement and reduced fertility, but does not lead to complete sterility, unlike pf16 mutations in other organisms. Using homology modelling, bioinformatics analysis and complementation studies in Chlamydomonas, we show that some regions of the PF16 protein are highly conserved across all eukaryotes, whereas other regions may have species-specific functions. PF16 is the first ARM-repeat protein characterised in the malaria parasite genus Plasmodium and this study opens up a novel model for analysis of Plasmodium flagellar biology that may provide unique insights into an ancient organelle and suggest novel intervention strategies to control the malaria parasite. PMID:20886115

Flagellar filament bio-templated inorganic oxide materials - towards an efficient lithium battery anode.

PubMed

Beznosov, Sergei N; Veluri, Pavan S; Pyatibratov, Mikhail G; Chatterjee, Abhijit; MacFarlane, Douglas R; Fedorov, Oleg V; Mitra, Sagar

2015-01-13

Designing a new generation of energy-intensive and sustainable electrode materials for batteries to power a variety of applications is an imperative task. The use of biomaterials as a nanosized structural template for these materials has the potential to produce hitherto unachievable structures. In this report, we have used genetically modified flagellar filaments of the extremely halophilic archaea species Halobacterium salinarum to synthesize nanostructured iron oxide composites for use as a lithium-ion battery anode. The electrode demonstrated a superior electrochemical performance compared to existing literature results, with good capacity retention of 1032 mAh g(-1) after 50 cycles and with high rate capability, delivering 770 mAh g(-1) at 5 A g(-1) (~5 C) discharge rate. This unique flagellar filament based template has the potential to provide access to other highly structured advanced energy materials in the future.

Flagellar oscillation: a commentary on proposed mechanisms.

PubMed

Woolley, David M

2010-08-01

Eukaryotic flagella and cilia have a remarkably uniform internal 'engine' known as the '9+2' axoneme. With few exceptions, the function of cilia and flagella is to beat rhythmically and set up relative motion between themselves and the liquid that surrounds them. The molecular basis of axonemal movement is understood in considerable detail, with the exception of the mechanism that provides its rhythmical or oscillatory quality. Some kind of repetitive 'switching' event is assumed to occur; there are several proposals regarding the nature of the 'switch' and how it might operate. Herein I first summarise all the factors known to influence the rate of the oscillation (the beating frequency). Many of these factors exert their effect through modulating the mean sliding velocity between the nine doublet microtubules of the axoneme, this velocity being the determinant of bend growth rate and bend propagation rate. Then I explain six proposed mechanisms for flagellar oscillation and review the evidence on which they are based. Finally, I attempt to derive an economical synthesis, drawing for preference on experimental research that has been minimally disruptive of the intricate structure of the axoneme. The 'provisional synthesis' is that flagellar oscillation emerges from an effect of passive sliding direction on the dynein arms. Sliding in one direction facilitates force-generating cycles and dynein-to-dynein synchronisation along a doublet; sliding in the other direction is inhibitory. The direction of the initial passive sliding normally oscillates because it is controlled hydrodynamically through the alternating direction of the propulsive thrust. However, in the absence of such regulation, there can be a perpetual, mechanical self-triggering through a reversal of sliding direction due to the recoil of elastic structures that deform as a response to the prior active sliding. This provisional synthesis may be a useful basis for further examination of the problem.

Variation in motor output and motor performance in a centrally generated motor pattern

PubMed Central

Norris, Brian J.; Doloc-Mihu, Anca; Calabrese, Ronald L.

2014-01-01

Central pattern generators (CPGs) produce motor patterns that ultimately drive motor outputs. We studied how functional motor performance is achieved, specifically, whether the variation seen in motor patterns is reflected in motor performance and whether fictive motor patterns differ from those in vivo. We used the leech heartbeat system in which a bilaterally symmetrical CPG coordinates segmental heart motor neurons and two segmented heart tubes into two mutually exclusive coordination modes: rear-to-front peristaltic on one side and nearly synchronous on the other, with regular side-to-side switches. We assessed individual variability of the motor pattern and the beat pattern in vivo. To quantify the beat pattern we imaged intact adults. To quantify the phase relations between motor neurons and heart constrictions we recorded extracellularly from two heart motor neurons and movement from the corresponding heart segments in minimally dissected leeches. Variation in the motor pattern was reflected in motor performance only in the peristaltic mode, where larger intersegmental phase differences in the motor neurons resulted in larger phase differences between heart constrictions. Fictive motor patterns differed from those in vivo only in the synchronous mode, where intersegmental phase differences in vivo had a larger front-to-rear bias and were more constrained. Additionally, load-influenced constriction timing might explain the amplification of the phase differences between heart segments in the peristaltic mode and the higher variability in motor output due to body shape assumed in this soft-bodied animal. The motor pattern determines the beat pattern, peristaltic or synchronous, but heart mechanics influence the phase relations achieved. PMID:24717348

The phylogeny of swimming kinematics: The environment controls flagellar waveforms in sperm motility

NASA Astrophysics Data System (ADS)

Guasto, Jeffrey; Burton, Lisa; Zimmer, Richard; Hosoi, Anette; Stocker, Roman

2013-11-01

In recent years, phylogenetic and molecular analyses have dominated the study of ecology and evolution. However, physical interactions between organisms and their environment, a fundamental determinant of organism ecology and evolution, are mediated by organism form and function, highlighting the need to understand the mechanics of basic survival strategies, including locomotion. Focusing on spermatozoa, we combined high-speed video microscopy and singular value decomposition analysis to quantitatively compare the flagellar waveforms of eight species, ranging from marine invertebrates to humans. We found striking similarities in sperm swimming kinematics between genetically dissimilar organisms, which could not be uncovered by phylogenetic analysis. The emergence of dominant waveform patterns across species are suggestive of biological optimization for flagellar locomotion and point toward environmental cues as drivers of this convergence. These results reinforce the power of quantitative kinematic analysis to understand the physical drivers of evolution and as an approach to uncover new solutions for engineering applications, such as micro-robotics.

Osmotaxis in Escherichia coli through changes in motor speed

PubMed Central

Rosko, Jerko; Martinez, Vincent A.; Poon, Wilson C. K.

2017-01-01

Bacterial motility, and in particular repulsion or attraction toward specific chemicals, has been a subject of investigation for over 100 years, resulting in detailed understanding of bacterial chemotaxis and the corresponding sensory network in many bacterial species. For Escherichia coli most of the current understanding comes from the experiments with low levels of chemotactically active ligands. However, chemotactically inactive chemical species at concentrations found in the human gastrointestinal tract produce significant changes in E. coli’s osmotic pressure and have been shown to lead to taxis. To understand how these nonspecific physical signals influence motility, we look at the response of individual bacterial flagellar motors under stepwise changes in external osmolarity. We combine these measurements with a population swimming assay under the same conditions. Unlike for chemotactic response, a long-term increase in swimming/motor speeds is observed, and in the motor rotational bias, both of which scale with the osmotic shock magnitude. We discuss how the speed changes we observe can lead to steady-state bacterial accumulation. PMID:28874571

Flagellar filament bio-templated inorganic oxide materials – towards an efficient lithium battery anode

PubMed Central

Beznosov, Sergei N.; Veluri, Pavan S.; Pyatibratov, Mikhail G.; Chatterjee, Abhijit; MacFarlane, Douglas R.; Fedorov, Oleg V.; Mitra, Sagar

2015-01-01

Designing a new generation of energy-intensive and sustainable electrode materials for batteries to power a variety of applications is an imperative task. The use of biomaterials as a nanosized structural template for these materials has the potential to produce hitherto unachievable structures. In this report, we have used genetically modified flagellar filaments of the extremely halophilic archaea species Halobacterium salinarum to synthesize nanostructured iron oxide composites for use as a lithium-ion battery anode. The electrode demonstrated a superior electrochemical performance compared to existing literature results, with good capacity retention of 1032 mAh g−1 after 50 cycles and with high rate capability, delivering 770 mAh g−1 at 5 A g−1 (~5 C) discharge rate. This unique flagellar filament based template has the potential to provide access to other highly structured advanced energy materials in the future. PMID:25583370

Association of Lis1 with outer arm dynein is modulated in response to alterations in flagellar motility

PubMed Central

Rompolas, Panteleimon; Patel-King, Ramila S.; King, Stephen M.

2012-01-01

The cytoplasmic dynein regulatory factor Lis1, which induces a persistent tight binding to microtubules and allows for transport of cargoes under high-load conditions, is also present in motile cilia/flagella. We observed that Lis1 levels in flagella of Chlamydomonas strains that exhibit defective motility due to mutation of various axonemal substructures were greatly enhanced compared with wild type; this increase was absolutely dependent on the presence within the flagellum of the outer arm dynein α heavy chain/light chain 5 thioredoxin unit. To assess whether cells might interpret defective motility as a “high-load environment,” we reduced the flagellar beat frequency of wild-type cells through enhanced viscous load and by reductive stress; both treatments resulted in increased levels of flagellar Lis1, which altered the intrinsic beat frequency of the trans flagellum. Differential extraction of Lis1 from wild-type and mutant axonemes suggests that the affinity of outer arm dynein for Lis1 is directly modulated. In cytoplasm, Lis1 localized to two punctate structures, one of which was located near the base of the flagella. These data reveal that the cell actively monitors motility and dynamically modulates flagellar levels of the dynein regulatory factor Lis1 in response to imposed alterations in beat parameters. PMID:22855525

Disruption of the A-Kinase Anchoring Domain in Flagellar Radial Spoke Protein 3 Results in Unregulated Axonemal cAMP-dependent Protein Kinase Activity and Abnormal Flagellar Motility

PubMed Central

Gaillard, Anne R.; Fox, Laura A.; Rhea, Jeanne M.; Craige, Branch

2006-01-01

Biochemical studies of Chlamydomonas flagellar axonemes revealed that radial spoke protein (RSP) 3 is an A-kinase anchoring protein (AKAP). To determine the physiological role of PKA anchoring in the axoneme, an RSP3 mutant, pf14, was transformed with an RSP3 gene containing a mutation in the PKA-binding domain. Analysis of several independent transformants revealed that the transformed cells exhibit an unusual phenotype: a fraction of the cells swim normally; the remainder of the cells twitch feebly or are paralyzed. The abnormal/paralyzed motility is not due to an obvious deficiency of radial spoke assembly, and the phenotype cosegregates with the mutant RSP3. We postulated that paralysis was due to failure in targeting and regulation of axonemal cAMP-dependent protein kinase (PKA). To test this, reactivation experiments of demembranated cells were performed in the absence or presence of PKA inhibitors. Importantly, motility in reactivated cell models mimicked the live cell phenotype with nearly equal fractions of motile and paralyzed cells. PKA inhibitors resulted in a twofold increase in the number of motile cells, rescuing paralysis. These results confirm that flagellar RSP3 is an AKAP and reveal that a mutation in the PKA binding domain results in unregulated axonemal PKA activity and inhibition of normal motility. PMID:16571668

Salmonella Enteritidis flagellar mutants have a colonization benefit in the chicken oviduct.

PubMed

Kilroy, Sofie; Raspoet, Ruth; Martel, An; Bosseler, Leslie; Appia-Ayme, Corinne; Thompson, Arthur; Haesebrouck, Freddy; Ducatelle, Richard; Van Immerseel, Filip

2017-02-01

Egg borne Salmonella Enteritidis is still a major cause of human food poisoning. Eggs can become internally contaminated following colonization of the hen's oviduct. In this paper we aimed to analyze the role of flagella of Salmonella Enteritidis in colonization of the hen's oviduct. Using a transposon library screen we showed that mutants lacking functional flagella are significantly more efficient in colonizing the hen's oviduct in vivo. A micro-array analysis proved that transcription of a number of flagellar genes is down-regulated inside chicken oviduct cells. Flagella contain flagellin, a pathogen associated molecular pattern known to bind to Toll-like receptor 5, activating a pro-inflammatory cascade. In vitro tests using primary oviduct cells showed that flagellin is not involved in invasion. Using a ligated loop model, a diminished inflammatory reaction was seen in the oviduct resulting from injection of an aflagellated mutant compared to the wild-type. It is hypothesized that Salmonella Enteritidis downregulates flagellar gene expression in the oviduct and consequently prevents a flagellin-induced inflammatory response, thereby increasing its oviduct colonization efficiency. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structural Insights into Membrane Targeting by the Flagellar Calcium-binding Protein (FCaBP) a Myristoylated and Palmitoylated Calcium Sensor in Trypanosoma cruzi

DOE Office of Scientific and Technical Information (OSTI.GOV)

J Wingard; J Ladner; M Vanarotti

2011-12-31

The flagellar calcium-binding protein (FCaBP) of the protozoan Trypanosoma cruzi is targeted to the flagellar membrane where it regulates flagellar function and assembly. As a first step toward understanding the Ca{sup 2+}-induced conformational changes important for membrane-targeting, we report here the x-ray crystal structure of FCaBP in the Ca{sup 2+}-free state determined at 2.2{angstrom} resolution. The first 17 residues from the N terminus appear unstructured and solvent-exposed. Residues implicated in membrane targeting (Lys-19, Lys-22, and Lys-25) are flanked by an exposed N-terminal helix (residues 26-37), forming a patch of positive charge on the protein surface that may interact electrostatically withmore » flagellar membrane targets. The four EF-hands in FCaBP each adopt a 'closed conformation' similar to that seen in Ca{sup 2+}-free calmodulin. The overall fold of FCaBP is closest to that of grancalcin and other members of the penta EF-hand superfamily. Unlike the dimeric penta EF-hand proteins, FCaBP lacks a fifth EF-hand and is monomeric. The unstructured N-terminal region of FCaBP suggests that its covalently attached myristoyl group at the N terminus may be solvent-exposed, in contrast to the highly sequestered myristoyl group seen in recoverin and GCAP1. NMR analysis demonstrates that the myristoyl group attached to FCaBP is indeed solvent-exposed in both the Ca{sup 2+}-free and Ca{sup 2+}-bound states, and myristoylation has no effect on protein structure and folding stability. We propose that exposed acyl groups at the N terminus may anchor FCaBP to the flagellar membrane and that Ca{sup 2+}-induced conformational changes may control its binding to membrane-bound protein targets..« less

Flagellar generated flow mediates attachment of Giardia lamblia

NASA Astrophysics Data System (ADS)

Urbach, Jeffrey; Luo, Haibei; Picou, Theodore; McAllister, Ryan; Elmendorf, Heidi

2011-03-01

Giardia lamblia is a protozoan parasite responsible for widespread diarrheal disease in humans and animals worldwide. Attachment to the host intestinal mucosa and resistance to peristalsis is necessary for establishing infection, but the physical basis for this attachment is poorly understood. We report results from TIRF and confocal fluorescence microscopy that demonstrate that the regular beating of the posterior flagella generate a flow through the ventral disk, a suction-cup shaped structure that is against the substrate during attachment. Finite element simulations are used to compare the negative pressure generated by the flow to the measured attachment force and the expected performance of the flagellar pump. NIH grant 1R21AI062934-0.

Testing the time-of-flight model for flagellar length sensing.

PubMed

Ishikawa, Hiroaki; Marshall, Wallace F

2017-11-07

Cilia and flagella are microtubule-based organelles that protrude from the surface of most cells, are important to the sensing of extracellular signals, and make a driving force for fluid flow. Maintenance of flagellar length requires an active transport process known as intraflagellar transport (IFT). Recent studies reveal that the amount of IFT injection negatively correlates with the length of flagella. These observations suggest that a length-dependent feedback regulates IFT. However, it is unknown how cells recognize the length of flagella and control IFT. Several theoretical models try to explain this feedback system. We focused on one of the models, the "time-of-flight" model, which measures the length of flagella on the basis of the travel time of IFT protein in the flagellar compartment. We tested the time-of-flight model using Chlamydomonas dynein mutant cells, which show slower retrograde transport speed. The amount of IFT injection in dynein mutant cells was higher than that in control cells. This observation does not support the prediction of the time-of-flight model and suggests that Chlamydomonas uses another length-control feedback system rather than that described by the time-of-flight model. © 2017 Ishikawa and Marshall. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

MotI (DgrA) acts as a molecular clutch on the flagellar stator protein MotA in Bacillus subtilis

PubMed Central

Subramanian, Sundharraman; Gao, Xiaohui; Dann, Charles E.; Kearns, Daniel B.

2017-01-01

Stator elements consisting of MotA4MotB2 complexes are anchored to the cell wall, extend through the cell membrane, and interact with FliG in the cytoplasmic C ring rotor of the flagellum. The cytoplasmic loop of MotA undergoes proton-driven conformational changes that drive flagellar rotation. Functional regulators inhibit motility by either disengaging or jamming the stator–rotor interaction. Here we show that the YcgR homolog MotI (formerly DgrA) of Bacillus subtilis inhibits motility like a molecular clutch that disengages MotA. MotI-inhibited flagella rotated freely by Brownian motion, and suppressor mutations in MotA that were immune to MotI inhibition were located two residues downstream of the critical force generation site. The 3D structure of MotI bound to c-di-GMP was solved, and MotI-fluorescent fusions localized as transient MotA-dependent puncta at the membrane when induced at subinhibitory levels. Finally, subinhibitory levels of MotI expression resulted in incomplete inhibition and proportional decreases in swimming speed. We propose a model in which flagellar stators are disengaged and sequestered from the flagellar rotor when bound by MotI. PMID:29196522

Specific arrangement of alpha-helical coiled coils in the core domain of the bacterial flagellar hook for the universal joint function.

PubMed

Fujii, Takashi; Kato, Takayuki; Namba, Keiichi

2009-11-11

The bacterial flagellar hook is a short, highly curved tubular structure connecting the rotary motor to the filament acting as a helical propeller. The bending flexibility of the hook allows it to work as a universal joint. A partial atomic model of the hook revealed a sliding intersubunit domain interaction along the protofilament to produce bending flexibility. However, it remained unclear how the tightly packed inner core domains can still permit axial extension and compression. We report advances in cryoEM image analysis for high-resolution, high-throughput structural analysis and a density map of the hook that reveals most of the secondary structures, including the terminal alpha helices forming a coiled coil. The orientations and axial packing interactions of these two alpha helices are distinctly different from those of the filament, allowing them to have a room for axial compression and extension for bending flexibility without impairing the mechanical stability of the hook.

Listeria monocytogenes DNA glycosylase AdiP affects flagellar motility, biofilm formation, virulence, and stress responses

USDA-ARS?s Scientific Manuscript database

The temperature-dependent alteration of flagellar motility gene expression is critical for the foodborne pathogen Listeria monocytogenes to respond to a changing environment. In this study, a genetic determinant, L. monocytogenes f2365_0220 (lmof2365_0220), encoding a putative protein that is struct...

Measurement of motor disability in MPTP-treated macaques using a telemetry system for estimating circadian motor activity.

PubMed

Barcia, C; De Pablos, V; Bautista-Hernández, V; Sanchez-Bahillo, A; Fernández-Barreiro, A; Poza, M; Herrero, M T

2004-03-15

The parkinsonian symptoms of primates after MPTP exposure can be measured by several visual methods (classical motor scores). However, these methods have a subjective bias, especially as regards the evaluation of the motor activity. Computerized monitoring systems represent an unbiased method for measuring the motor disability of monkeys after MPTP administration. In this work the motor activity of monkeys before and after MPTP administration is measured and compared with the activity of a control intact group by means of a telemetry system. A pronounced decrease in motor activity was observed after MPTP administration. These results suggest the monitoring method used is suited for characterizing the motor incapacity and possible improvements following treatments to test different therapies to control Parkinson's disease in MPTP models involving primates.

Protein export through the bacterial flagellar type III export pathway.

PubMed

Minamino, Tohru

2014-08-01

For construction of the bacterial flagellum, which is responsible for bacterial motility, the flagellar type III export apparatus utilizes both ATP and proton motive force across the cytoplasmic membrane and exports flagellar proteins from the cytoplasm to the distal end of the nascent structure. The export apparatus consists of a membrane-embedded export gate made of FlhA, FlhB, FliO, FliP, FliQ, and FliR and a water-soluble ATPase ring complex consisting of FliH, FliI, and FliJ. FlgN, FliS, and FliT act as substrate-specific chaperones that do not only protect their cognate substrates from degradation and aggregation in the cytoplasm but also efficiently transfer the substrates to the export apparatus. The ATPase ring complex facilitates the initial entry of the substrates into the narrow pore of the export gate. The export gate by itself is a proton-protein antiporter that uses the two components of proton motive force, the electric potential difference and the proton concentration difference, for different steps of the export process. A specific interaction of FlhA with FliJ located in the center of the ATPase ring complex allows the export gate to efficiently use proton motive force to drive protein export. The ATPase ring complex couples ATP binding and hydrolysis to its assembly-disassembly cycle for rapid and efficient protein export cycle. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey. © 2013 Elsevier B.V. All rights reserved.

Computer simulation of flagellar movement. VI. Simple curvature-controlled models are incompletely specified.

PubMed

Brokaw, C J

1985-10-01

Computer simulation is used to examine a simple flagellar model that will initiate and propagate bending waves in the absence of viscous resistances. The model contains only an elastic bending resistance and an active sliding mechanism that generates reduced active shear moment with increasing sliding velocity. Oscillation results from a distributed control mechanism that reverses the direction of operation of the active sliding mechanism when the curvature reaches critical magnitudes in either direction. Bend propagation by curvature-controlled flagellar models therefore does not require interaction with the viscous resistance of an external fluid. An analytical examination of moment balance during bend propagation by this model yields a solution curve giving values of frequency and wavelength that satisfy the moment balance equation and give uniform bend propagation, suggesting that the model is underdetermined. At 0 viscosity, the boundary condition of 0 shear rate at the basal end of the flagellum during the development of new bends selects the particular solution that is obtained by computer simulations. Therefore, the details of the pattern of bend initiation at the basal end of a flagellum can be of major significance in determining the properties of propagated bending waves in the distal portion of a flagellum. At high values of external viscosity, the model oscillates at frequencies and wavelengths that give approximately integral numbers of waves on the flagellum. These operating points are selected because they facilitate the balance of bending moments at the ends of the model, where the external viscous moment approaches 0. These mode preferences can be overridden by forcing the model to operate at a predetermined frequency. The strong mode preferences shown by curvature-controlled flagellar models, in contrast to the weak or absent mode preferences shown by real flagella, therefore do not demonstrate the inapplicability of the moment-balance approach

Curcumin Reduces the Motility of Salmonella enterica Serovar Typhimurium by Binding to the Flagella, Thereby Leading to Flagellar Fragility and Shedding

PubMed Central

Balakrishnan, Arjun; Negi, Vidya Devi; Sakorey, Deepika; Chandra, Nagasuma

2016-01-01

ABSTRACT One of the important virulence properties of the pathogen is its ability to travel to a favorable environment, cross the viscous mucus barrier (intestinal barrier for enteric pathogens), and reach the epithelia to initiate pathogenesis with the help of an appendage, like flagella. Nonetheless, flagella can act as an “Achilles heel,” revealing the pathogen's presence to the host through the stimulation of innate and adaptive immune responses. We assessed whether curcumin, a dietary polyphenol, could alter the motility of Salmonella, a foodborne pathogen. It reduced the motility of Salmonella enterica serovar Typhimurium by shortening the length of the flagellar filament (from ∼8 μm to ∼5 μm) and decreasing its density (4 or 5 flagella/bacterium instead of 8 or 9 flagella/bacterium). Upon curcumin treatment, the percentage of flagellated bacteria declined from ∼84% to 59%. However, no change was detected in the expression of the flagellin gene and protein. A fluorescence binding assay demonstrated binding of curcumin to the flagellar filament. This might make the filament fragile, breaking it into smaller fragments. Computational analysis predicted the binding of curcumin, its analogues, and its degraded products to a flagellin molecule at an interface between domains D1 and D2. Site-directed mutagenesis and a fluorescence binding assay confirmed the binding of curcumin to flagellin at residues ASN120, ASP123, ASN163, SER164, ASN173, and GLN175. IMPORTANCE This work, to our knowledge the first report of its kind, examines how curcumin targets flagellar density and affects the pathogenesis of bacteria. We found that curcumin does not affect any of the flagellar synthesis genes. Instead, it binds to the flagellum and makes it fragile. It increases the torsional stress on the flagellar filament that then breaks, leaving fewer flagella around the bacteria. Flagella, which are crucial ligands for Toll-like receptor 5, are some of the most important

Flagellar Cap Protein FliD Mediates Adherence of Atypical Enteropathogenic Escherichia coli to Enterocyte Microvilli

PubMed Central

Sampaio, Suely C. F.; Luiz, Wilson B.; Vieira, Mônica A. M.; Ferreira, Rita C. C.; Garcia, Bruna G.; Sinigaglia-Coimbra, Rita; Sampaio, Jorge L. M.; Ferreira, Luís C. S.

2016-01-01

The expression of flagella correlates with different aspects of bacterial pathogenicity, ranging from adherence to host cells to activation of inflammatory responses by the innate immune system. In the present study, we investigated the role of flagella in the adherence of an atypical enteropathogenic Escherichia coli (aEPEC) strain (serotype O51:H40) to human enterocytes. Accordingly, isogenic mutants deficient in flagellin (FliC), the flagellar structural subunit; the flagellar cap protein (FliD); or the MotAB proteins, involved in the control of flagellar motion, were generated and tested for binding to differentiated Caco-2 cells. Binding of the aEPEC strain to enterocytes was significantly impaired in strains with the fliC and fliD genes deleted, both of which could not form flagella on the bacterial surface. A nonmotile but flagellated MotAB mutant also showed impaired adhesion to Caco-2 cells. In accordance with these observations, adhesion of aEPEC strain 1711-4 to Caco-2 cells was drastically reduced after the treatment of Caco-2 cells with purified FliD. In addition, incubation of aEPEC bacteria with specific anti-FliD serum impaired binding to Caco-2 cells. Finally, incubation of Caco-2 cells with purified FliD, followed by immunolabeling, showed that the protein was specifically bound to the microvillus tips of differentiated Caco-2 cells. The aEPEC FliD or anti-FliD serum also reduced the adherence of prototype typical enteropathogenic, enterohemorrhagic, and enterotoxigenic E. coli strains to Caco-2 cells. In conclusion, our findings further strengthened the role of flagella in the adherence of aEPEC to human enterocytes and disclosed the relevant structural and functional involvement of FliD in the adhesion process. PMID:26831466

Microscopic Analysis of Bacterial Motility at High Pressure

PubMed Central

Nishiyama, Masayoshi; Sowa, Yoshiyuki

2012-01-01

The bacterial flagellar motor is a molecular machine that converts an ion flux to the rotation of a helical flagellar filament. Counterclockwise rotation of the filaments allows them to join in a bundle and propel the cell forward. Loss of motility can be caused by environmental factors such as temperature, pH, and solvation. Hydrostatic pressure is also a physical inhibitor of bacterial motility, but the detailed mechanism of this inhibition is still unknown. Here, we developed a high-pressure microscope that enables us to acquire high-resolution microscopic images, regardless of applied pressures. We also characterized the pressure dependence of the motility of swimming Escherichia coli cells and the rotation of single flagellar motors. The fraction and speed of swimming cells decreased with increased pressure. At 80 MPa, all cells stopped swimming and simply diffused in solution. After the release of pressure, most cells immediately recovered their initial motility. Direct observation of the motility of single flagellar motors revealed that at 80 MPa, the motors generate torque that should be sufficient to join rotating filaments in a bundle. The discrepancy in the behavior of free swimming cells and individual motors could be due to the applied pressure inhibiting the formation of rotating filament bundles that can propel the cell body in an aqueous environment. PMID:22768943

Auditory-Motor Interactions in Pediatric Motor Speech Disorders: Neurocomputational Modeling of Disordered Development

PubMed Central

Terband, H.; Maassen, B.; Guenther, F.H.; Brumberg, J.

2014-01-01

Background/Purpose Differentiating the symptom complex due to phonological-level disorders, speech delay and pediatric motor speech disorders is a controversial issue in the field of pediatric speech and language pathology. The present study investigated the developmental interaction between neurological deficits in auditory and motor processes using computational modeling with the DIVA model. Method In a series of computer simulations, we investigated the effect of a motor processing deficit alone (MPD), and the effect of a motor processing deficit in combination with an auditory processing deficit (MPD+APD) on the trajectory and endpoint of speech motor development in the DIVA model. Results Simulation results showed that a motor programming deficit predominantly leads to deterioration on the phonological level (phonemic mappings) when auditory self-monitoring is intact, and on the systemic level (systemic mapping) if auditory self-monitoring is impaired. Conclusions These findings suggest a close relation between quality of auditory self-monitoring and the involvement of phonological vs. motor processes in children with pediatric motor speech disorders. It is suggested that MPD+APD might be involved in typically apraxic speech output disorders and MPD in pediatric motor speech disorders that also have a phonological component. Possibilities to verify these hypotheses using empirical data collected from human subjects are discussed. PMID:24491630

Electrical stimulation of motor cortex in the uninjured hemisphere after chronic unilateral injury promotes recovery of skilled locomotion through ipsilateral control.

PubMed

Carmel, Jason B; Kimura, Hiroki; Martin, John H

2014-01-08

Partial injury to the corticospinal tract (CST) causes sprouting of intact axons at their targets, and this sprouting correlates with functional improvement. Electrical stimulation of motor cortex augments sprouting of intact CST axons and promotes functional recovery when applied soon after injury. We hypothesized that electrical stimulation of motor cortex in the intact hemisphere after chronic lesion of the CST in the other hemisphere would restore function through ipsilateral control. To test motor skill, rats were trained and tested to walk on a horizontal ladder with irregularly spaced rungs. Eight weeks after injury, produced by pyramidal tract transection, half of the rats received forelimb motor cortex stimulation of the intact hemisphere. Rats with injury and stimulation had significantly improved forelimb control compared with rats with injury alone and achieved a level of proficiency similar to uninjured rats. To test whether recovery of forelimb function was attributable to ipsilateral control, we selectively inactivated the stimulated motor cortex using the GABA agonist muscimol. The dose of muscimol we used produces strong contralateral but no ipsilateral impairments in naive rats. In rats with injury and stimulation, but not those with injury alone, inactivation caused worsening of forelimb function; the initial deficit was reinstated. These results demonstrate that electrical stimulation can promote recovery of motor function when applied late after injury and that motor control can be exerted from the ipsilateral motor cortex. These results suggest that the uninjured motor cortex could be targeted for brain stimulation in people with large unilateral CST lesions.

Novel Single-Tube Agar-Based Test System for Motility Enhancement and Immunocapture of Escherichia coli O157:H7 by H7 Flagellar Antigen-Specific Antibodies

PubMed Central

Murinda, Shelton E.; Nguyen, Lien T.; Ivey, Susan J.; Almeida, Raul A.; Oliver, Stephen P.

2002-01-01

This paper describes a novel single-tube agar-based technique for motility enhancement and immunoimmobilization of Escherichia coli O157:H7. Motility indole ornithine medium and agar (0.4%, wt/vol) media containing either nutrient broth, tryptone broth, or tryptic soy broth (TSBA) were evaluated for their abilities to enhance bacterial motility. Twenty-six E. coli strains, including 19 O157:H7 strains, 1 O157:H− strain, and 6 generic E. coli strains, were evaluated. Test bacteria were stab inoculated in the center of the agar column, and tubes were incubated at 37°C for 18 to 96 h. Nineteen to 24 of the 26 test strains (73.1 to 92.3%) were motile in the different media. TSBA medium performed best and was employed in subsequent studies of motility enhancement and H7 flagellar immunocapture. H7 flagellar antiserum (30 and 60 μl) mixed with TSBA was placed as a band (1 ml) in the middle of an agar column separating the top (3-ml) and bottom (3-ml) agar layers. The top agar layer was inoculated with the test bacterial strains. The tubes were incubated at 37°C for 12 to 18 h and for 18 to 96 h. The specificity and sensitivity of the H7 flagellar immunocapture tests were 75 and 100%, respectively. The procedure described is simple and sensitive and could be adapted easily for routine use in laboratories that do not have sophisticated equipment and resources for confirming the presence of H7 flagellar antigens. Accurate and rapid identification of H7 flagellar antigen is critical for the complete characterization of E. coli O157:H7, owing to the immense clinical, public health, and economic significance of this food-borne pathogen. PMID:12454173

Combined motor cortex and spinal cord neuromodulation promotes corticospinal system functional and structural plasticity and motor function after injury

PubMed Central

Song, Weiguo; Amer, Alzahraa; Ryan, Daniel; Martin, John H.

2016-01-01

An important strategy for promoting voluntary movements after motor system injury is to harness activity-dependent corticospinal tract (CST) plasticity. We combine forelimb motor cortex (M1) activation with co-activation of its cervical spinal targets in rats to promote CST sprouting and skilled limb movement after pyramidal tract lesion (PTX). We used a two-step experimental design in which we first established the optimal combined stimulation protocol in intact rats and then used the optimal protocol in injured animals to promote CST repair and motor recovery. M1 was activated epidurally using an electrical analog of intermittent theta burst stimulation (iTBS). The cervical spinal cord was co-activated by trans-spinal direct current stimulation (tsDCS) that was targeted to the cervical enlargement, simulated from finite element method. In intact rats, forelimb motor evoked potentials (MEPs) were strongly facilitated during iTBS and for 10 minutes after cessation of stimulation. Cathodal, not anodal, tsDCS alone facilitated MEPs and also produced a facilitatory aftereffect that peaked at 10 minutes. Combined iTBS and cathodal tsDCS (c-tsDCS) produced further MEP enhancement during stimulation, but without further aftereffect enhancement. Correlations between forelimb M1 local field potentials and forelimb electromyogram (EMG) during locomotion increased after electrical iTBS alone and further increased with combined stimulation (iTBS + c-tsDCS). This optimized combined stimulation was then used to promote function after PTX because it enhanced functional connections between M1 and spinal circuits and greater M1 engagement in muscle contraction than either stimulation alone. Daily application of combined M1 iTBS on the intact side and c-tsDCS after PTX (10 days, 27 minutes/day) significantly restored skilled movements during horizontal ladder walking. Stimulation produced a 5.4-fold increase in spared ipsilateral CST terminations. Combined neuromodulation achieves

Assembly and stoichiometry of the core structure of the bacterial flagellar type III export gate complex.

PubMed

Fukumura, Takuma; Makino, Fumiaki; Dietsche, Tobias; Kinoshita, Miki; Kato, Takayuki; Wagner, Samuel; Namba, Keiichi; Imada, Katsumi; Minamino, Tohru

2017-08-01

The bacterial flagellar type III export apparatus, which is required for flagellar assembly beyond the cell membranes, consists of a transmembrane export gate complex and a cytoplasmic ATPase complex. FlhA, FlhB, FliP, FliQ, and FliR form the gate complex inside the basal body MS ring, although FliO is required for efficient export gate formation in Salmonella enterica. However, it remains unknown how they form the gate complex. Here we report that FliP forms a homohexameric ring with a diameter of 10 nm. Alanine substitutions of conserved Phe-137, Phe-150, and Glu-178 residues in the periplasmic domain of FliP (FliPP) inhibited FliP6 ring formation, suppressing flagellar protein export. FliO formed a 5-nm ring structure with 3 clamp-like structures that bind to the FliP6 ring. The crystal structure of FliPP derived from Thermotoga maritia, and structure-based photo-crosslinking experiments revealed that Phe-150 and Ser-156 of FliPP are involved in the FliP-FliP interactions and that Phe-150, Arg-152, Ser-156, and Pro-158 are responsible for the FliP-FliO interactions. Overexpression of FliP restored motility of a ∆fliO mutant to the wild-type level, suggesting that the FliP6 ring is a functional unit in the export gate complex and that FliO is not part of the final gate structure. Copurification assays revealed that FlhA, FlhB, FliQ, and FliR are associated with the FliO/FliP complex. We propose that the assembly of the export gate complex begins with FliP6 ring formation with the help of the FliO scaffold, followed by FliQ, FliR, and FlhB and finally FlhA during MS ring formation.

Assembly and stoichiometry of the core structure of the bacterial flagellar type III export gate complex

PubMed Central

Fukumura, Takuma; Makino, Fumiaki; Dietsche, Tobias; Kinoshita, Miki; Kato, Takayuki; Wagner, Samuel; Namba, Keiichi; Imada, Katsumi

2017-01-01

The bacterial flagellar type III export apparatus, which is required for flagellar assembly beyond the cell membranes, consists of a transmembrane export gate complex and a cytoplasmic ATPase complex. FlhA, FlhB, FliP, FliQ, and FliR form the gate complex inside the basal body MS ring, although FliO is required for efficient export gate formation in Salmonella enterica. However, it remains unknown how they form the gate complex. Here we report that FliP forms a homohexameric ring with a diameter of 10 nm. Alanine substitutions of conserved Phe-137, Phe-150, and Glu-178 residues in the periplasmic domain of FliP (FliPP) inhibited FliP6 ring formation, suppressing flagellar protein export. FliO formed a 5-nm ring structure with 3 clamp-like structures that bind to the FliP6 ring. The crystal structure of FliPP derived from Thermotoga maritia, and structure-based photo-crosslinking experiments revealed that Phe-150 and Ser-156 of FliPP are involved in the FliP–FliP interactions and that Phe-150, Arg-152, Ser-156, and Pro-158 are responsible for the FliP–FliO interactions. Overexpression of FliP restored motility of a ∆fliO mutant to the wild-type level, suggesting that the FliP6 ring is a functional unit in the export gate complex and that FliO is not part of the final gate structure. Copurification assays revealed that FlhA, FlhB, FliQ, and FliR are associated with the FliO/FliP complex. We propose that the assembly of the export gate complex begins with FliP6 ring formation with the help of the FliO scaffold, followed by FliQ, FliR, and FlhB and finally FlhA during MS ring formation. PMID:28771466

Mechanism of gastrointestinal abnormal motor activity induced by cisplatin in conscious dogs.

PubMed

Ando, Hiroyuki; Mochiki, Erito; Ohno, Tetsuro; Yanai, Mitsuhiro; Toyomasu, Yoshitaka; Ogata, Kyoichi; Tabe, Yuichi; Aihara, Ryuusuke; Nakabayashi, Toshihiro; Asao, Takayuki; Kuwano, Hiroyuki

2014-11-14

To investigate whether 5-hydroxytryptamine (serotonin; 5-HT) is involved in mediating abnormal motor activity in dogs after cisplatin administration. After the dogs had been given a 2-wk recovery period, all of them were administered cisplatin, and the motor activity was recorded using strain gauge force transducers. Blood and intestinal fluid samples were collected to measure 5-HT for 24 h. To determine whether 5-HT in plasma or that in intestinal fluids is more closely related to abnormal motor activity we injected 5-HT into the bloodstream and the intestinal tract of the dogs. Cisplatin given intravenously produced abnormal motor activity that lasted up to 5 h. From 3 to 4 h after cisplatin administration, normal intact dogs exhibited retropropagation of motor activity accompanied by emesis. The concentration of 5-HT in plasma reached the peak at 4 h, and that in intestinal fluids reached the peak at 3 h. In normal intact dogs with resection of the vagus nerve that were administered kytril, cisplatin given intravenously did not produce abnormal motor activity. Intestinal serotonin administration did not produce abnormal motor activity, but intravenous serotonin administration did. After the intravenous administration of cisplatin, abnormal motor activity was produced in the involved vagus nerve and in the involved serotonergic neurons via another pathway. This study was the first to determine the relationship between 5-HT and emesis-induced motor activity.

Motor nerve transplantation.

PubMed

Gray, W P; Keohane, C; Kirwan, W O

1997-10-01

The motor nerve transplantation (MNT) technique is used to transfer an intact nerve into a denervated muscle by harvesting a neurovascular pedicle of muscle containing motor endplates from the motor endplate zone of a donor muscle and implanting it into a denervated muscle. Thirty-six adult New Zealand White rabbits underwent reinnervation of the left long peroneal (LP) muscle (fast twitch) with a motor nerve graft from the soleus muscle (slow twitch). The right LP muscle served as a control. Reinnervation was assessed using microstimulatory single-fiber electromyography (SFEMG), alterations in muscle fiber typing and grouping, and isometric response curves. Neurofilament antibody was used for axon staining. The neurofilament studies provided direct evidence of nerve growth from the motor nerve graft into the adjacent denervated muscle. Median motor endplate jitter was 13 microsec preoperatively, and 26 microsec at 2 months, 29.5 microsec at 4 months, and 14 microsec at 6 months postoperatively (p < 0.001). Isometric tetanic tension studies showed a progressive functional recovery in the reinnervated muscle over 6 months. There was no histological evidence of aberrant reinnervation from any source outside the nerve pedicle. Isometric twitch responses and adenosine triphosphatase studies confirmed the conversion of the reinnervated LP muscle to a slow-type muscle. Acetylcholinesterase studies confirmed the presence of functioning motor endplates beneath the insertion of the motor nerve graft. It is concluded that the MNT technique achieves motor reinnervation by growth of new nerve fibers across the pedicle graft into the recipient muscle.

Polymorphic transformation of helical flagella of bacteria

NASA Astrophysics Data System (ADS)

Lim, Sookkyung; Howard Berg Collaboration; William Ko Collaboration; Yongsam Kim Collaboration; Wanho Lee Collaboration; Charles Peskin Collaboration

2016-11-01

Bacteria such as E. coli swim in an aqueous environment by utilizing the rotation of flagellar motors and alternate two modes of motility, runs and tumbles. Runs are steady forward swimming driven by bundles of flagellar filaments whose motors are turning CCW; tumbles involve a reorientation of the direction of swimming triggered by motor reversals. During tumbling, the helical flagellum undergoes polymorphic transformations, which is a local change in helical pitch, helical radius, and handedness. In this work, we investigate the underlying mechanism of structural conformation and how this polymorphic transition plays a role in bacterial swimming. National Science Foundation.

Are there intracellular Ca2+ oscillations correlated with flagellar beating in human sperm? A three vs. two-dimensional analysis.

PubMed

Corkidi, G; Montoya, F; Hernández-Herrera, P; Ríos-Herrera, W A; Müller, M F; Treviño, C L; Darszon, A

2017-09-01

Are there intracellular Ca2+ ([Ca2+]i) oscillations correlated with flagellar beating in human sperm? The results reveal statistically significant [Ca2+]i oscillations that are correlated with the human sperm flagellar beating frequency, when measured in three-dimensions (3D). Fast [Ca2+]i oscillations that are correlated to the beating flagellar frequency of cells swimming in a restricted volume have been detected in hamster sperm. To date, such findings have not been confirmed in any other mammalian sperm species. An important question that has remained regarding these observations is whether the fast [Ca2+]i oscillations are real or might they be due to remaining defocusing effects of the Z component arising from the 3D beating of the flagella. Healthy donors whose semen samples fulfill the WHO criteria between the age of 18-28 were selected. Cells from at least six different donors were utilized for analysis. Approximately the same number of experimental and control cells were analyzed. Motile cells were obtained by the swim-up technique and were loaded with Fluo-4 (Ca2+ sensitive dye) or with Calcein (Ca2+ insensitive dye). Ni2+ was used as a non-specific plasma membrane Ca2+ channel blocker. Fluorescence data and flagella position were acquired in 3D. Each cell was recorded for up to 5.6 s within a depth of 16 microns with a high speed camera (coupled to an image intensifier) acquiring at a rate of 3000 frames per second, while an oscillating objective vibrated at 90 Hz via a piezoelectric device. From these samples, eight experimental and nine control sperm cells were analyzed in both 2D and 3D. We have implemented a new system that allows [Ca2+]i measurements of the human sperm flagellum beating in 3D. These measurements reveal statistically significant [Ca2+]i oscillations that correlate with the flagellar beating frequency. These oscillations may arise from intracellular sources and/or Ca2+ transporters, as they were insensitive to external Ni2+, a non

Neural correlates of the age-related changes in motor sequence learning and motor adaptation in older adults

PubMed Central

King, Bradley R.; Fogel, Stuart M.; Albouy, Geneviève; Doyon, Julien

2013-01-01

As the world's population ages, a deeper understanding of the relationship between aging and motor learning will become increasingly relevant in basic research and applied settings. In this context, this review aims to address the effects of age on motor sequence learning (MSL) and motor adaptation (MA) with respect to behavioral, neurological, and neuroimaging findings. Previous behavioral research investigating the influence of aging on motor learning has consistently reported the following results. First, the initial acquisition of motor sequences is not altered, except under conditions of increased task complexity. Second, older adults demonstrate deficits in motor sequence memory consolidation. And, third, although older adults demonstrate deficits during the exposure phase of MA paradigms, the aftereffects following removal of the sensorimotor perturbation are similar to young adults, suggesting that the adaptive ability of older adults is relatively intact. This paper will review the potential neural underpinnings of these behavioral results, with a particular emphasis on the influence of age-related dysfunctions in the cortico-striatal system on motor learning. PMID:23616757

Mechanism of gastrointestinal abnormal motor activity induced by cisplatin in conscious dogs

PubMed Central

Ando, Hiroyuki; Mochiki, Erito; Ohno, Tetsuro; Yanai, Mitsuhiro; Toyomasu, Yoshitaka; Ogata, Kyoichi; Tabe, Yuichi; Aihara, Ryuusuke; Nakabayashi, Toshihiro; Asao, Takayuki; Kuwano, Hiroyuki

2014-01-01

AIM: To investigate whether 5-hydroxytryptamine (serotonin; 5-HT) is involved in mediating abnormal motor activity in dogs after cisplatin administration. METHODS: After the dogs had been given a 2-wk recovery period, all of them were administered cisplatin, and the motor activity was recorded using strain gauge force transducers. Blood and intestinal fluid samples were collected to measure 5-HT for 24 h. To determine whether 5-HT in plasma or that in intestinal fluids is more closely related to abnormal motor activity we injected 5-HT into the bloodstream and the intestinal tract of the dogs. RESULTS: Cisplatin given intravenously produced abnormal motor activity that lasted up to 5 h. From 3 to 4 h after cisplatin administration, normal intact dogs exhibited retropropagation of motor activity accompanied by emesis. The concentration of 5-HT in plasma reached the peak at 4 h, and that in intestinal fluids reached the peak at 3 h. In normal intact dogs with resection of the vagus nerve that were administered kytril, cisplatin given intravenously did not produce abnormal motor activity. Intestinal serotonin administration did not produce abnormal motor activity, but intravenous serotonin administration did. CONCLUSION: After the intravenous administration of cisplatin, abnormal motor activity was produced in the involved vagus nerve and in the involved serotonergic neurons via another pathway. This study was the first to determine the relationship between 5-HT and emesis-induced motor activity. PMID:25400453

Altering the speract-induced ion permeability changes that generate flagellar Ca2+ spikes regulates their kinetics and sea urchin sperm motility.

PubMed

Wood, Christopher D; Nishigaki, Takuya; Tatsu, Yoshiro; Yumoto, Noboru; Baba, Shoji A; Whitaker, Michael; Darszon, Alberto

2007-06-15

Speract, an egg-derived sperm-activating peptide, induces changes in intracellular Ca2+, Na+, pH, cAMP, cGMP, and membrane potential in sperm of the sea urchin Strongylocentrotus purpuratus. Ca2+ is a key regulator of motility in all sperm and, in many marine species, is required for generating turns interspersed with straighter swimming paths that are essential for chemotaxis towards the egg. We show that speract triggers a train of increases in flagellar Ca2+, and that each individual Ca2+ fluctuation induces a transient increase in flagellar asymmetry that leads to a turn. We also find that modifying the amplitude, duration and interval between individual Ca2+ fluctuations by treating sperm with niflumic acid, an inhibitor of Ca2+-activated Cl(-) channels, correspondingly alters the properties of the sperm turns. We conclude that Ca2+ entry through a fast flagellar pathway not only induces sperm turns, but the kinetics of Ca2+ entry may shape the nature of these turns, and that these kinetics are tuned by other channels, possibly including Cl(-) channels. In addition, the speract-induced changes in sperm motility closely resemble those seen during chemotaxis in other marine organisms, yet speract is not a chemoattractant. This implies the Ca2+-induced motility changes are necessary but not sufficient for chemotaxis.

Flagellar Kinematics and Swimming of Algal Cells in Viscoelastic Fluids

PubMed Central

Qin, B.; Gopinath, A.; Yang, J.; Gollub, J. P.; Arratia, P. E.

2015-01-01

The motility of microorganisms is influenced greatly by their hydrodynamic interactions with the fluidic environment they inhabit. We show by direct experimental observation of the bi-flagellated alga Chlamydomonas reinhardtii that fluid elasticity and viscosity strongly influence the beating pattern - the gait - and thereby control the propulsion speed. The beating frequency and the wave speed characterizing the cyclical bending are both enhanced by fluid elasticity. Despite these enhancements, the net swimming speed of the alga is hindered for fluids that are sufficiently elastic. The origin of this complex response lies in the interplay between the elasticity-induced changes in the spatial and temporal aspects of the flagellar cycle and the buildup and subsequent relaxation of elastic stresses during the power and recovery strokes. PMID:25778677

A continuum theoretical model and finite elements simulation of bacterial flagellar filament phase transition.

PubMed

Wang, Xiaoling; Meng, Shuo; Han, Jingshi

2017-10-03

The Bacterial flagellar filament can undergo a polymorphic phase transition in response to both mechanical and chemical variations in vitro and in vivo environments. Under mechanical stimuli, such as viscous flow or forces induced by motor rotation, the filament changes its phase from left-handed normal (N) to right-handed semi-coiled (SC) via phase nucleation and growth. Our detailed mechanical analysis of existing experiments shows that both torque and bending moment contribute to the filament phase transition. In this paper, we establish a non-convex and non-local continuum model based on the Ginzburg-Landau theory to describe main characteristics of the filament phase transition such as new-phase nucleation, growth, propagation and the merging of neighboring interfaces. The finite element method (FEM) is adopted to simulate the phase transition under a displacement-controlled loading condition (rotation angle and bending deflection). We show that new-phase nucleation corresponds to the maximum torque and bending moment at the stuck end of the filament. The hysteresis loop in the loading and unloading curves indicates energy dissipation. When the new phase grows and propagates, torque and bending moment remain static. We also find that there is a drop in load when the two interfaces merge, indicating a concomitant reduction in the interfacial energy. Finally, the interface thickness is governed by the coefficients of the gradient of order parameters in the non-local interface energy. Our continuum theory and the finite element method provide a method to study the mechanical behavior of such biomaterials. Copyright © 2017 Elsevier Ltd. All rights reserved.

Recruitment of rat diaphragm motor units across motor behaviors with different levels of diaphragm activation.

PubMed

Seven, Yasin B; Mantilla, Carlos B; Sieck, Gary C

2014-12-01

Phrenic motor neurons are recruited across a range of motor behaviors to generate varying levels of diaphragm muscle (DIAm) force. We hypothesized that DIAm motor units are recruited in a fixed order across a range of motor behaviors of varying force levels, consistent with the Henneman Size Principle. Single motor unit action potentials and compound DIAm EMG activities were recorded in anesthetized, neurally intact rats across different motor behaviors, i.e., eupnea, hypoxia-hypercapnia (10% O2 and 5% CO2), deep breaths, sustained airway occlusion, and sneezing. Central drive [estimated by root-mean-squared (RMS) EMG value 75 ms after the onset of EMG activity (RMS75)], recruitment delay, and onset discharge frequencies were similar during eupnea and hypoxia-hypercapnia. Compared with eupnea, central drive increased (∼25%) during deep breaths, and motor units were recruited ∼12 ms earlier (P < 0.01). During airway occlusion, central drive was ∼3 times greater, motor units were recruited ∼30 ms earlier (P < 0.01), and motor unit onset discharge frequencies were significantly higher (P < 0.01). Recruitment order of motor unit pairs observed during eupnea was maintained for 98%, 87%, and 84% of the same pairs recorded during hypoxia-hypercapnia, deep breaths, and airway occlusion, respectively. Reversals in motor unit recruitment order were observed primarily if motor unit pairs were recruited <20 ms apart. These results are consistent with DIAm motor unit recruitment order being determined primarily by the intrinsic size-dependent electrophysiological properties of phrenic motor neurons. Copyright © 2014 the American Physiological Society.

Recruitment of rat diaphragm motor units across motor behaviors with different levels of diaphragm activation

PubMed Central

Seven, Yasin B.; Mantilla, Carlos B.

2014-01-01

Phrenic motor neurons are recruited across a range of motor behaviors to generate varying levels of diaphragm muscle (DIAm) force. We hypothesized that DIAm motor units are recruited in a fixed order across a range of motor behaviors of varying force levels, consistent with the Henneman Size Principle. Single motor unit action potentials and compound DIAm EMG activities were recorded in anesthetized, neurally intact rats across different motor behaviors, i.e., eupnea, hypoxia-hypercapnia (10% O2 and 5% CO2), deep breaths, sustained airway occlusion, and sneezing. Central drive [estimated by root-mean-squared (RMS) EMG value 75 ms after the onset of EMG activity (RMS75)], recruitment delay, and onset discharge frequencies were similar during eupnea and hypoxia-hypercapnia. Compared with eupnea, central drive increased (∼25%) during deep breaths, and motor units were recruited ∼12 ms earlier (P < 0.01). During airway occlusion, central drive was ∼3 times greater, motor units were recruited ∼30 ms earlier (P < 0.01), and motor unit onset discharge frequencies were significantly higher (P < 0.01). Recruitment order of motor unit pairs observed during eupnea was maintained for 98%, 87%, and 84% of the same pairs recorded during hypoxia-hypercapnia, deep breaths, and airway occlusion, respectively. Reversals in motor unit recruitment order were observed primarily if motor unit pairs were recruited <20 ms apart. These results are consistent with DIAm motor unit recruitment order being determined primarily by the intrinsic size-dependent electrophysiological properties of phrenic motor neurons. PMID:25257864

Combined motor cortex and spinal cord neuromodulation promotes corticospinal system functional and structural plasticity and motor function after injury.

PubMed

Song, Weiguo; Amer, Alzahraa; Ryan, Daniel; Martin, John H

2016-03-01

An important strategy for promoting voluntary movements after motor system injury is to harness activity-dependent corticospinal tract (CST) plasticity. We combine forelimb motor cortex (M1) activation with co-activation of its cervical spinal targets in rats to promote CST sprouting and skilled limb movement after pyramidal tract lesion (PTX). We used a two-step experimental design in which we first established the optimal combined stimulation protocol in intact rats and then used the optimal protocol in injured animals to promote CST repair and motor recovery. M1 was activated epidurally using an electrical analog of intermittent theta burst stimulation (iTBS). The cervical spinal cord was co-activated by trans-spinal direct current stimulation (tsDCS) that was targeted to the cervical enlargement, simulated from finite element method. In intact rats, forelimb motor evoked potentials (MEPs) were strongly facilitated during iTBS and for 10 min after cessation of stimulation. Cathodal, not anodal, tsDCS alone facilitated MEPs and also produced a facilitatory aftereffect that peaked at 10 min. Combined iTBS and cathodal tsDCS (c-tsDCS) produced further MEP enhancement during stimulation, but without further aftereffect enhancement. Correlations between forelimb M1 local field potentials and forelimb electromyogram (EMG) during locomotion increased after electrical iTBS alone and further increased with combined stimulation (iTBS+c-tsDCS). This optimized combined stimulation was then used to promote function after PTX because it enhanced functional connections between M1 and spinal circuits and greater M1 engagement in muscle contraction than either stimulation alone. Daily application of combined M1 iTBS on the intact side and c-tsDCS after PTX (10 days, 27 min/day) significantly restored skilled movements during horizontal ladder walking. Stimulation produced a 5.4-fold increase in spared ipsilateral CST terminations. Combined neuromodulation achieves optimal motor

Mutations in Genes Involved in the Flagellar Export Apparatus of the Solvent-Tolerant Pseudomonas putida DOT-T1E Strain Impair Motility and Lead to Hypersensitivity to Toluene Shocks

PubMed Central

Segura, Ana; Duque, Estrella; Hurtado, Ana; Ramos, Juan L.

2001-01-01

Pseudomonas putida DOT-T1E is a solvent-tolerant strain able to grow in the presence of 1% (vol/vol) toluene in the culture medium. Random mutagenesis with mini-Tn5-′phoA-Km allowed us to isolate a mutant strain (DOT-T1E-42) that formed blue colonies on Luria-Bertani medium supplemented with 5-bromo-4-chloro-3-indolylphosphate and that, in contrast to the wild-type strain, was unable to tolerate toluene shocks (0.3%, vol/vol). The mutant strain exhibited patterns of tolerance or sensitivity to a number of antibiotics, detergents, and chelating agents similar to those of the wild-type strain. The mutation in this strain therefore seemed to specifically affect toluene tolerance. Cloning and sequencing of the mutation revealed that the mini-Tn5-′phoA-Km was inserted within the fliP gene, which is part of the fliLMNOPQRflhBA cluster, a set of genes that encode flagellar structure components. FliP is involved in the export of flagellar proteins, and in fact, the P. putida fliP mutant was nonmotile. The finding that, after replacing the mutant allele with the wild-type one, the strain recovered the wild-type pattern of toluene tolerance and motility unequivocally assigned FliP a function in solvent resistance. An flhB knockout mutant, another gene component of the flagellar export apparatus, was also nonmotile and hypersensitive to toluene. In contrast, a nonpolar mutation at the fliL gene, which encodes a cytoplasmic membrane protein associated with the flagellar basal body, yielded a nonmotile yet toluene-resistant strain. The results are discussed regarding a possible role of the flagellar export apparatus in the transport of one or more proteins necessary for toluene tolerance in P. putida DOT-T1E to the periplasm. PMID:11418551

Progressive motor cortex functional reorganization following 6-hydroxydopamine lesioning in rats.

PubMed

Viaro, Riccardo; Morari, Michele; Franchi, Gianfranco

2011-03-23

Many studies have attempted to correlate changes of motor cortex activity with progression of Parkinson's disease, although results have been controversial. In the present study we used intracortical microstimulation (ICMS) combined with behavioral testing in 6-hydroxydopamine hemilesioned rats to evaluate the impact of dopamine depletion on movement representations in primary motor cortex (M1) and motor behavior. ICMS allows for motor-effective stimulation of corticofugal neurons in motor areas so as to obtain topographic movements representations based on movement type, area size, and threshold currents. Rats received unilateral 6-hydroxydopamine in the nigrostriatal bundle, causing motor impairment. Changes in M1 were time dependent and bilateral, although stronger in the lesioned than the intact hemisphere. Representation size and threshold current were maximally impaired at 15 d, although inhibition was still detectable at 60-120 d after lesion. Proximal forelimb movements emerged at the expense of the distal ones. Movement lateralization was lost mainly at 30 d after lesion. Systemic L-3,4-dihydroxyphenylalanine partially attenuated motor impairment and cortical changes, particularly in the caudal forelimb area, and completely rescued distal forelimb movements. Local application of the GABA(A) antagonist bicuculline partially restored cortical changes, particularly in the rostral forelimb area. The local anesthetic lidocaine injected into the M1 of the intact hemisphere restored movement lateralization in the lesioned hemisphere. This study provides evidence for motor cortex remodeling after unilateral dopamine denervation, suggesting that cortical changes were associated with dopamine denervation, pathogenic intracortical GABA inhibition, and altered interhemispheric activity.

The Lipid Raft Proteome of African Trypanosomes Contains Many Flagellar Proteins.

PubMed

Sharma, Aabha I; Olson, Cheryl L; Engman, David M

2017-08-24

Lipid rafts are liquid-ordered membrane microdomains that form by preferential association of 3-β-hydroxysterols, sphingolipids and raft-associated proteins often having acyl modifications. We isolated lipid rafts of the protozoan parasite Trypanosoma brucei and determined the protein composition of lipid rafts in the cell. This analysis revealed a striking enrichment of flagellar proteins and several putative signaling proteins in the lipid raft proteome. Calpains and intraflagellar transport proteins, in particular, were found to be abundant in the lipid raft proteome. These findings provide additional evidence supporting the notion that the eukaryotic cilium/flagellum is a lipid raft-enriched specialized structure with high concentrations of sterols, sphingolipids and palmitoylated proteins involved in environmental sensing and cell signaling.

Instabilities of a rotating helical rod

NASA Astrophysics Data System (ADS)

Park, Yunyoung; Ko, William; Kim, Yongsam; Lim, Sookkyung

2016-11-01

Bacteria such as Escherichia coli and Vibrio alginolyticus have helical flagellar filament. By rotating a motor, which is located at the bottom end of the flagellar filament embedded in the cell body, CCW or CW, they swim forward or backward. We model a left-handed helix by the Kirchhoff rod theory and use regularized Stokes formulation to study an interaction between the surrounding fluid and the flagellar filament. We perform numerical studies focusing on relations between physical parameters and critical angular frequency of the motor, which separates overwhiring from twirling. We are also interested in the buckling instability of the hook, which is very flexible elastic rod. By measuring buckling angle, which is an angle between rotational axis and helical axis, we observe the effects of physical parameters on buckling of the hook.

Evidence for Loss of a Partial Flagellar Glycolytic Pathway during Trypanosomatid Evolution

PubMed Central

Brown, Robert W. B.; Collingridge, Peter W.; Gull, Keith; Rigden, Daniel J.; Ginger, Michael L.

2014-01-01

Classically viewed as a cytosolic pathway, glycolysis is increasingly recognized as a metabolic pathway exhibiting surprisingly wide-ranging variations in compartmentalization within eukaryotic cells. Trypanosomatid parasites provide an extreme view of glycolytic enzyme compartmentalization as several glycolytic enzymes are found exclusively in peroxisomes. Here, we characterize Trypanosoma brucei flagellar proteins resembling glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoglycerate kinase (PGK): we show the latter associates with the axoneme and the former is a novel paraflagellar rod component. The paraflagellar rod is an essential extra-axonemal structure in trypanosomes and related protists, providing a platform into which metabolic activities can be built. Yet, bioinformatics interrogation and structural modelling indicate neither the trypanosome PGK-like nor the GAPDH-like protein is catalytically active. Orthologs are present in a free-living ancestor of the trypanosomatids, Bodo saltans: the PGK-like protein from B. saltans also lacks key catalytic residues, but its GAPDH-like protein is predicted to be catalytically competent. We discuss the likelihood that the trypanosome GAPDH-like and PGK-like proteins constitute molecular evidence for evolutionary loss of a flagellar glycolytic pathway, either as a consequence of niche adaptation or the re-localization of glycolytic enzymes to peroxisomes and the extensive changes to glycolytic flux regulation that accompanied this re-localization. Evidence indicating loss of localized ATP provision via glycolytic enzymes therefore provides a novel contribution to an emerging theme of hidden diversity with respect to compartmentalization of the ubiquitous glycolytic pathway in eukaryotes. A possibility that trypanosome GAPDH-like protein additionally represents a degenerate example of a moonlighting protein is also discussed. PMID:25050549

Tracking the Re-organization of Motor Functions After Disconnective Surgery: A Longitudinal fMRI and DTI Study

PubMed Central

Rosazza, Cristina; Deleo, Francesco; D'Incerti, Ludovico; Antelmi, Luigi; Tringali, Giovanni; Didato, Giuseppe; Bruzzone, Maria G.; Villani, Flavio; Ghielmetti, Francesco

2018-01-01

Objective: Mechanisms of motor plasticity are critical to maintain motor functions after cerebral damage. This study explores the mechanisms of motor reorganization occurring before and after surgery in four patients with drug-refractory epilepsy candidate to disconnective surgery. Methods: We studied four patients with early damage, who underwent tailored hemispheric surgery in adulthood, removing the cortical motor areas and disconnecting the corticospinal tract (CST) from the affected hemisphere. Motor functions were assessed clinically, with functional MRI (fMRI) tasks of arm and leg movement and Diffusion Tensor Imaging (DTI) before and after surgery with assessments of up to 3 years. Quantifications of fMRI motor activations and DTI fractional anisotropy (FA) color maps were performed to assess the lateralization of motor network. We hypothesized that lateralization of motor circuits assessed preoperatively with fMRI and DTI was useful to evaluate the motor outcome in these patients. Results: In two cases preoperative DTI-tractography did not reconstruct the CST, and FA-maps were strongly asymmetric. In the other two cases, the affected CST appeared reduced compared to the contralateral one, with modest asymmetry in the FA-maps. fMRI showed different degrees of lateralization of the motor network and the SMA of the intact hemisphere was mostly engaged in all cases. After surgery, patients with a strongly lateralized motor network showed a stable performance. By contrast, a patient with a more bilateral pattern showed worsening of the upper limb function. For all cases, fMRI activations shifted to the intact hemisphere. Structural alterations of motor circuits, observed with FA values, continued beyond 1 year after surgery. Conclusion: In our case series fMRI and DTI could track the longitudinal reorganization of motor functions. In these four patients the more the paretic limbs recruited the intact hemisphere in primary motor and associative areas, the

Tracking the Re-organization of Motor Functions After Disconnective Surgery: A Longitudinal fMRI and DTI Study.

PubMed

Rosazza, Cristina; Deleo, Francesco; D'Incerti, Ludovico; Antelmi, Luigi; Tringali, Giovanni; Didato, Giuseppe; Bruzzone, Maria G; Villani, Flavio; Ghielmetti, Francesco

2018-01-01

Objective: Mechanisms of motor plasticity are critical to maintain motor functions after cerebral damage. This study explores the mechanisms of motor reorganization occurring before and after surgery in four patients with drug-refractory epilepsy candidate to disconnective surgery. Methods: We studied four patients with early damage, who underwent tailored hemispheric surgery in adulthood, removing the cortical motor areas and disconnecting the corticospinal tract (CST) from the affected hemisphere. Motor functions were assessed clinically, with functional MRI (fMRI) tasks of arm and leg movement and Diffusion Tensor Imaging (DTI) before and after surgery with assessments of up to 3 years. Quantifications of fMRI motor activations and DTI fractional anisotropy (FA) color maps were performed to assess the lateralization of motor network. We hypothesized that lateralization of motor circuits assessed preoperatively with fMRI and DTI was useful to evaluate the motor outcome in these patients. Results: In two cases preoperative DTI-tractography did not reconstruct the CST, and FA-maps were strongly asymmetric. In the other two cases, the affected CST appeared reduced compared to the contralateral one, with modest asymmetry in the FA-maps. fMRI showed different degrees of lateralization of the motor network and the SMA of the intact hemisphere was mostly engaged in all cases. After surgery, patients with a strongly lateralized motor network showed a stable performance. By contrast, a patient with a more bilateral pattern showed worsening of the upper limb function. For all cases, fMRI activations shifted to the intact hemisphere. Structural alterations of motor circuits, observed with FA values, continued beyond 1 year after surgery. Conclusion: In our case series fMRI and DTI could track the longitudinal reorganization of motor functions. In these four patients the more the paretic limbs recruited the intact hemisphere in primary motor and associative areas, the

Auditory-motor interactions in pediatric motor speech disorders: neurocomputational modeling of disordered development.

PubMed

Terband, H; Maassen, B; Guenther, F H; Brumberg, J

2014-01-01

Differentiating the symptom complex due to phonological-level disorders, speech delay and pediatric motor speech disorders is a controversial issue in the field of pediatric speech and language pathology. The present study investigated the developmental interaction between neurological deficits in auditory and motor processes using computational modeling with the DIVA model. In a series of computer simulations, we investigated the effect of a motor processing deficit alone (MPD), and the effect of a motor processing deficit in combination with an auditory processing deficit (MPD+APD) on the trajectory and endpoint of speech motor development in the DIVA model. Simulation results showed that a motor programming deficit predominantly leads to deterioration on the phonological level (phonemic mappings) when auditory self-monitoring is intact, and on the systemic level (systemic mapping) if auditory self-monitoring is impaired. These findings suggest a close relation between quality of auditory self-monitoring and the involvement of phonological vs. motor processes in children with pediatric motor speech disorders. It is suggested that MPD+APD might be involved in typically apraxic speech output disorders and MPD in pediatric motor speech disorders that also have a phonological component. Possibilities to verify these hypotheses using empirical data collected from human subjects are discussed. The reader will be able to: (1) identify the difficulties in studying disordered speech motor development; (2) describe the differences in speech motor characteristics between SSD and subtype CAS; (3) describe the different types of learning that occur in the sensory-motor system during babbling and early speech acquisition; (4) identify the neural control subsystems involved in speech production; (5) describe the potential role of auditory self-monitoring in developmental speech disorders. Copyright © 2014 Elsevier Inc. All rights reserved.

Flagellar motility is a key determinant of the magnitude of the inflammasome response to Pseudomonas aeruginosa.

PubMed

Patankar, Yash R; Lovewell, Rustin R; Poynter, Matthew E; Jyot, Jeevan; Kazmierczak, Barbara I; Berwin, Brent

2013-06-01

We previously demonstrated that bacterial flagellar motility is a fundamental mechanism by which host phagocytes bind and ingest bacteria. Correspondingly, loss of bacterial motility, consistently observed in clinical isolates from chronic Pseudomonas aeruginosa infections, enables bacteria to evade association and ingestion of P. aeruginosa by phagocytes both in vitro and in vivo. Since bacterial interactions with the phagocyte cell surface are required for type three secretion system-dependent NLRC4 inflammasome activation by P. aeruginosa, we hypothesized that reduced bacterial association with phagocytes due to loss of bacterial motility, independent of flagellar expression, will lead to reduced inflammasome activation. Here we report that inflammasome activation is reduced in response to nonmotile P. aeruginosa. Nonmotile P. aeruginosa elicits reduced IL-1β production as well as caspase-1 activation by peritoneal macrophages and bone marrow-derived dendritic cells in vitro. Importantly, nonmotile P. aeruginosa also elicits reduced IL-1β levels in vivo in comparison to those elicited by wild-type P. aeruginosa. This is the first demonstration that loss of bacterial motility results in reduced inflammasome activation and antibacterial IL-1β host response. These results provide a critical insight into how the innate immune system responds to bacterial motility and, correspondingly, how pathogens have evolved mechanisms to evade the innate immune system.

Flagellar Motility Is a Key Determinant of the Magnitude of the Inflammasome Response to Pseudomonas aeruginosa

PubMed Central

Patankar, Yash R.; Lovewell, Rustin R.; Poynter, Matthew E.; Jyot, Jeevan; Kazmierczak, Barbara I.

2013-01-01

We previously demonstrated that bacterial flagellar motility is a fundamental mechanism by which host phagocytes bind and ingest bacteria. Correspondingly, loss of bacterial motility, consistently observed in clinical isolates from chronic Pseudomonas aeruginosa infections, enables bacteria to evade association and ingestion of P. aeruginosa by phagocytes both in vitro and in vivo. Since bacterial interactions with the phagocyte cell surface are required for type three secretion system-dependent NLRC4 inflammasome activation by P. aeruginosa, we hypothesized that reduced bacterial association with phagocytes due to loss of bacterial motility, independent of flagellar expression, will lead to reduced inflammasome activation. Here we report that inflammasome activation is reduced in response to nonmotile P. aeruginosa. Nonmotile P. aeruginosa elicits reduced IL-1β production as well as caspase-1 activation by peritoneal macrophages and bone marrow-derived dendritic cells in vitro. Importantly, nonmotile P. aeruginosa also elicits reduced IL-1β levels in vivo in comparison to those elicited by wild-type P. aeruginosa. This is the first demonstration that loss of bacterial motility results in reduced inflammasome activation and antibacterial IL-1β host response. These results provide a critical insight into how the innate immune system responds to bacterial motility and, correspondingly, how pathogens have evolved mechanisms to evade the innate immune system. PMID:23529619

Heavy tailed bacterial motor switching statistics define macroscopic transport properties during upstream contamination by E. coli

NASA Astrophysics Data System (ADS)

Figueroa-Morales, N.; Rivera, A.; Altshuler, E.; Darnige, T.; Douarche, C.; Soto, R.; Lindner, A.; Clément, E.

The motility of E. Coli bacteria is described as a run and tumble process. Changes of direction correspond to a switch in the flagellar motor rotation. The run time distribution is described as an exponential decay of characteristic time close to 1s. Remarkably, it has been demonstrated that the generic response for the distribution of run times is not exponential, but a heavy tailed power law decay, which is at odds with the motility findings. We investigate the consequences of the motor statistics in the macroscopic bacterial transport. During upstream contamination processes in very confined channels, we have identified very long contamination tongues. Using a stochastic model considering bacterial dwelling times on the surfaces related to the run times, we are able to reproduce qualitatively and quantitatively the evolution of the contamination profiles when considering the power law run time distribution. However, the model fails to reproduce the qualitative dynamics when the classical exponential run and tumble distribution is considered. Moreover, we have corroborated the existence of a power law run time distribution by means of 3D Lagrangian tracking. We then argue that the macroscopic transport of bacteria is essentially determined by the motor rotation statistics.

Common Evolutionary Origin for the Rotor Domain of Rotary Atpases and Flagellar Protein Export Apparatus

PubMed Central

Kishikawa, Jun-ichi; Ibuki, Tatsuya; Nakamura, Shuichi; Nakanishi, Astuko; Minamino, Tohru; Miyata, Tomoko; Namba, Keiichi; Konno, Hiroki; Ueno, Hiroshi; Imada, Katsumi; Yokoyama, Ken

2013-01-01

The V1- and F1- rotary ATPases contain a rotor that rotates against a catalytic A3B3 or α3β3 stator. The rotor F1-γ or V1-DF is composed of both anti-parallel coiled coil and globular-loop parts. The bacterial flagellar type III export apparatus contains a V1/F1-like ATPase ring structure composed of FliI6 homo-hexamer and FliJ which adopts an anti-parallel coiled coil structure without the globular-loop part. Here we report that FliJ of Salmonella enterica serovar Typhimurium shows a rotor like function in Thermus thermophilus A3B3 based on both biochemical and structural analysis. Single molecular analysis indicates that an anti-parallel coiled-coil structure protein (FliJ structure protein) functions as a rotor in A3B3. A rotary ATPase possessing an F1-γ-like protein generated by fusion of the D and F subunits of V1 rotates, suggesting F1-γ could be the result of a fusion of the genes encoding two separate rotor subunits. Together with sequence comparison among the globular part proteins, the data strongly suggest that the rotor domains of the rotary ATPases and the flagellar export apparatus share a common evolutionary origin. PMID:23724081

An intact action-perception coupling depends on the integrity of the cerebellum.

PubMed

Christensen, Andrea; Giese, Martin A; Sultan, Fahad; Mueller, Oliver M; Goericke, Sophia L; Ilg, Winfried; Timmann, Dagmar

2014-05-07

It is widely accepted that action and perception in humans functionally interact on multiple levels. Moreover, areas originally suggested to be predominantly motor-related, as the cerebellum, are also involved in action observation. However, as yet, few studies provided unequivocal evidence that the cerebellum is involved in the action perception coupling (APC), specifically in the integration of motor and multisensory information for perception. We addressed this question studying patients with focal cerebellar lesions in a virtual-reality paradigm measuring the effect of action execution on action perception presenting self-generated movements as point lights. We measured the visual sensitivity to the point light stimuli based on signal detection theory. Compared with healthy controls cerebellar patients showed no beneficial influence of action execution on perception indicating deficits in APC. Applying lesion symptom mapping, we identified distinct areas in the dentate nucleus and the lateral cerebellum of both hemispheres that are causally involved in APC. Lesions of the right ventral dentate, the ipsilateral motor representations (lobules V/VI), and most interestingly the contralateral posterior cerebellum (lobule VII) impede the benefits of motor execution on perception. We conclude that the cerebellum establishes time-dependent multisensory representations on different levels, relevant for motor control as well as supporting action perception. Ipsilateral cerebellar motor representations are thought to support the somatosensory state estimate of ongoing movements, whereas the ventral dentate and the contralateral posterior cerebellum likely support sensorimotor integration in the cerebellar-parietal loops. Both the correct somatosensory as well as the multisensory state representations are vital for an intact APC.

The Lipid Raft Proteome of African Trypanosomes Contains Many Flagellar Proteins

PubMed Central

Sharma, Aabha I.; Olson, Cheryl L.; Engman, David M.

2017-01-01

Lipid rafts are liquid-ordered membrane microdomains that form by preferential association of 3-β-hydroxysterols, sphingolipids and raft-associated proteins often having acyl modifications. We isolated lipid rafts of the protozoan parasite Trypanosoma brucei and determined the protein composition of lipid rafts in the cell. This analysis revealed a striking enrichment of flagellar proteins and several putative signaling proteins in the lipid raft proteome. Calpains and intraflagellar transport proteins, in particular, were found to be abundant in the lipid raft proteome. These findings provide additional evidence supporting the notion that the eukaryotic cilium/flagellum is a lipid raft-enriched specialized structure with high concentrations of sterols, sphingolipids and palmitoylated proteins involved in environmental sensing and cell signaling. PMID:28837104

Cerebellum and Ocular Motor Control

PubMed Central

Kheradmand, Amir; Zee, David S.

2011-01-01

An intact cerebellum is a prerequisite for optimal ocular motor performance. The cerebellum fine-tunes each of the subtypes of eye movements so they work together to bring and maintain images of objects of interest on the fovea. Here we review the major aspects of the contribution of the cerebellum to ocular motor control. The approach will be based on structural–functional correlation, combining the effects of lesions and the results from physiologic studies, with the emphasis on the cerebellar regions known to be most closely related to ocular motor function: (1) the flocculus/paraflocculus for high-frequency (brief) vestibular responses, sustained pursuit eye movements, and gaze holding, (2) the nodulus/ventral uvula for low-frequency (sustained) vestibular responses, and (3) the dorsal oculomotor vermis and its target in the posterior portion of the fastigial nucleus (the fastigial oculomotor region) for saccades and pursuit initiation. PMID:21909334

Peripheral Nerve Injury in Developing Rats Reorganizes Representation Pattern in Motor Cortex

NASA Astrophysics Data System (ADS)

Donoghue, John P.; Sanes, Jerome N.

1987-02-01

We investigated the effect of neonatal nerve lesions on cerebral motor cortex organization by comparing the cortical motor representation of normal adult rats with adult rats that had one forelimb removed on the day of birth. Mapping of cerebral neocortex with electrical stimulation revealed an altered relationship between the motor cortex and the remaining muscles. Whereas distal forelimb movements are normally elicited at the lowest threshold in the motor cortex forelimb area, the same stimuli activated shoulder and trunk muscles in experimental animals. In addition, an expanded cortical representation of intact body parts was present and there was an absence of a distinct portion of motor cortex. These data demonstrate that representation patterns in motor cortex can be altered by peripheral nerve injury during development.

Three Members of the LC8/DYNLL Family Are Required for Outer Arm Dynein Motor Function

PubMed Central

Tanner, Christopher A.; Rompolas, Panteleimon; Patel-King, Ramila S.; Gorbatyuk, Oksana; Wakabayashi, Ken-ichi; Pazour, Gregory J.

2008-01-01

The highly conserved LC8/DYNLL family proteins were originally identified in axonemal dyneins and subsequently found to function in multiple enzyme systems. Genomic analysis uncovered a third member (LC10) of this protein class in Chlamydomonas. The LC10 protein is extracted from flagellar axonemes with 0.6 M NaCl and cofractionates with the outer dynein arm in sucrose density gradients. Furthermore, LC10 is specifically missing only from axonemes of those strains that fail to assemble outer dynein arms. Previously, the oda12-1 insertional allele was shown to lack the Tctex2-related dynein light chain LC2. The LC10 gene is located ∼2 kb from that of LC2 and is also completely missing from this mutant but not from oda12-2, which lacks only the 3′ end of the LC2 gene. Although oda12-1 cells assemble outer arms that lack only LC2 and LC10, this strain exhibits a flagellar beat frequency that is consistently less than that observed for strains that fail to assemble the entire outer arm and docking complex (e.g., oda1). These results support a key regulatory role for the intermediate chain/light chain complex that is an integral and highly conserved feature of all oligomeric dynein motors. PMID:18579685

Following the Viterbi Path to Deduce Flagellar Actin-Interacting Proteins of Leishmania spp.: Report on Cofilins and Twinfilins

NASA Astrophysics Data System (ADS)

Pacheco, Ana Carolina L.; Araújo, Fabiana F.; Kamimura, Michel T.; Medeiros, Sarah R.; Viana, Daniel A.; Oliveira, Fátima de Cássia E.; Filho, Raimundo Araújo; Costa, Marcília P.; Oliveira, Diana M.

2007-11-01

For performing vital cellular processes, such as motility, eukaryotic cells rely on the actin cytoskeleton, whose structure and dynamics are tightly controlled by a large number of actin-interacting (AIP) or actin-related/regulating (ARP) proteins. Trypanosomatid protozoa, such as Leishmania, rely on their flagellum for motility and sensory reception, which are believed to allow parasite migration, adhesion, invasion and even persistence on mammalian host tissues to cause disease. Actin can determine cell stiffness and transmit force during mechanotransduction, cytokinesis, cell motility and other cellular shape changes, while the identification and analyses of AIPs can help to improve understanding of their mechanical properties on physiological architectures, such as the present case regarding Leishmania flagellar apparatus. This work conveniently apply bioinformatics tools in some refined pattern recognition techniques (such as hidden Markov models (HMMs) through the Viterbi algorithm/path) in order to improve the recognition of actin-binding/interacting activity through identification of AIPs in genomes, transcriptomes and proteomes of Leishmania species. We here report cofilin and twinfilin as putative components of the flagellar apparatus, a direct bioinformatics contribution in the secondary annotation of Leishmania and trypanosomatid genomes.

Modulation of flagellar expression in Escherichia coli by acetyl phosphate and the osmoregulator OmpR.

PubMed Central

Shin, S; Park, C

1995-01-01

During the search for unknown factors involved in motility, we have found that expression of the flagellar master operon flhDC is affected by mutations of the pta and ackA genes, encoding phosphotransacetylase and acetate kinase, respectively (S. Shin, J. Sheen, and C. Park, Korean J. Microbiol. 31:504-511, 1993). Here we describe results showing that this effect is modulated by externally added acetate, except when both pta and ackA are mutated, suggesting the role of acetyl phosphate, an intermediate of acetate metabolism, as a regulatory effector. Furthermore, the following evidence indicates that the phosphorylation of OmpR, a trans factor for osmoregulation, regulates flagellar expression. First, in a strain lacking ompR, the expression of flhDC is no longer responsive to a change in the level of acetyl phosphate. Second, an increase in medium osmolarity does not decrease flhDC expression in an ompR mutant. It is known that such an increase normally enhances OmpR phosphorylation. Third, OmpR protein binds to the DNA fragment containing the flhDC promoter, and its affinity is increased with phosphorylation by acetyl phosphate. DNase I footprinting revealed the regions of the flhDC promoter protected by OmpR in the presence or absence of phosphorylation. Therefore, we propose that the phosphorylated OmpR, generated by either osmolarity change or the internal level of acetyl phosphate, negatively regulates the expression of flagella. PMID:7642497

Modulation of flagellar expression in Escherichia coli by acetyl phosphate and the osmoregulator OmpR.

PubMed

Shin, S; Park, C

1995-08-01

During the search for unknown factors involved in motility, we have found that expression of the flagellar master operon flhDC is affected by mutations of the pta and ackA genes, encoding phosphotransacetylase and acetate kinase, respectively (S. Shin, J. Sheen, and C. Park, Korean J. Microbiol. 31:504-511, 1993). Here we describe results showing that this effect is modulated by externally added acetate, except when both pta and ackA are mutated, suggesting the role of acetyl phosphate, an intermediate of acetate metabolism, as a regulatory effector. Furthermore, the following evidence indicates that the phosphorylation of OmpR, a trans factor for osmoregulation, regulates flagellar expression. First, in a strain lacking ompR, the expression of flhDC is no longer responsive to a change in the level of acetyl phosphate. Second, an increase in medium osmolarity does not decrease flhDC expression in an ompR mutant. It is known that such an increase normally enhances OmpR phosphorylation. Third, OmpR protein binds to the DNA fragment containing the flhDC promoter, and its affinity is increased with phosphorylation by acetyl phosphate. DNase I footprinting revealed the regions of the flhDC promoter protected by OmpR in the presence or absence of phosphorylation. Therefore, we propose that the phosphorylated OmpR, generated by either osmolarity change or the internal level of acetyl phosphate, negatively regulates the expression of flagella.

Preliminary evidence of motor impairment among polysubstance 3,4-methylenedioxymethamphetamine users with intact neuropsychological functioning

PubMed Central

BOUSMAN, CHAD A.; CHERNER, MARIANA; EMORY, KRISTEN T.; BARRON, DANIEL; GREBENSTEIN, PATRICIA; ATKINSON, J. HAMPTON; HEATON, ROBERT K.; GRANT, IGOR

2013-01-01

Neuropsychological disturbances have been reported in association with use of the recreational drug “ecstasy,” or 3,4-methylenedioxymethamphetamine (MDMA), but findings have been inconsistent. We performed comprehensive neuropsychological testing examining seven ability domains in 21 MDMA users (MDMA+) and 21 matched control participants (MDMA−). Among MDMA+ participants, median [interquartile range] lifetime MDMA use was 186 [111, 516] doses, with 120 [35–365] days of abstinence. There were no significant group differences in neuropsychological performance, with the exception of the motor speed/dexterity domain in which 43% of MDMA+ were impaired compared with 5% of MDMA− participants (p = .004). Motor impairment differences were not explained by use of other substances and were unrelated to length of abstinence or lifetime number of MDMA doses. Findings provide limited evidence for neuropsychological differences between MDMA+ and MDMA− participants with the exception of motor impairments observed in the MDMA+ group. However, replication of this finding in a larger sample is warranted. PMID:20735886

Comparison of Intact PTH and Bio-Intact PTH Assays Among Non-Dialysis Dependent Chronic Kidney Disease Patients.

PubMed

Einbinder, Yael; Benchetrit, Sydney; Golan, Eliezer; Zitman-Gal, Tali

2017-09-01

The third-generation bio-intact parathyroid hormone (PTH) (1-84) assay was designed to overcome problems associated with the detection of C-terminal fragments by the second-generation intact PTH assay. The two assays have been compared primarily among dialysis populations. The present study evaluated the correlations and differences between these two PTH assays among patients with chronic kidney disease (CKD) stages 3 to 5 not yet on dialysis. Blood samples were collected from 98 patients with CKD stages 3 to 5. PTH concentrations were measured simultaneously by using the second-generation - PTH intact-STAT and third-generation bio-intact 1-84 PTH assays. Other serum biomarkers of bone mineral disorders were also assessed. CKD stage was calculated by using the CKD-Epidemiology Collaboration (EPI) formula. Serum bio-intact PTH concentrations were strongly correlated but significantly lower than the intact PTH concentrations (r=0.963, P<0.0001). This finding was consistent among CKD stages 3 to 5. PTH concentrations by both assays (intact and bio-intact PTH) positively correlated with urea (r=0.523, r=0.504; P=0.002, respectively), phosphorus (r=0.532, r=0.521; P<0.0001, respectively) and negatively correlated with blood calcium (r=-0.435, r=-0.476; P<0.0001, respectively), 25(OH) vitamin D, (r=-0.319, r=-0.353; respectively, P<0.0001) and the estimated glomerular filtration rate (r=-0.717, r=-0.688; P<0.0001, respectively). Among patients with CKD stages 3 to 5 not on dialysis, the bio-intact PTH assay detected significantly lower PTH concentrations compared with intact PTH assay. Additional studies that correlate the diagnosis and management of CKD mineral and bone disorders with bone histomorphometric findings are needed to determine whether bio-intact PTH assay results are better surrogate markers in these early stages of CKD. © The Korean Society for Laboratory Medicine

Recollections of Parent Characteristics and Attachment Patterns for College Women of Intact vs. Non-Intact Families

ERIC Educational Resources Information Center

Kilmann, Peter R.; Carranza, Laura V.; Vendemia, Jennifer M. C.

2006-01-01

This study contrasted offsprings' attachment patterns and recollections of parent characteristics in two college samples: 147 females from intact biological parents and 157 females of parental divorce. Secure females from intact or non-intact families rated parents positively, while insecure females rated parents as absent, distant, and demanding.…

Natural descriptions of motor behavior: examples from E. coli and C. elegans.

NASA Astrophysics Data System (ADS)

Ryu, William

2007-03-01

E. coli has a natural behavioral variable - the direction of rotation of its flagellar rotorary motor. Monitoring this one-dimensional behavioral response in reaction to chemical perturbation has been instrumental in the understanding of how E. coli performs chemotaxis at the genetic, physiological, and computational level. Here we apply this experimental strategy to the study of bacterial thermotaxis - a sensory mode that is less well understood. We investigate bacterial thermosensation by studying the motor response of single cells subjected to impulses of heat produced by an IR laser. A simple temperature dependent modification to an existing chemotaxis model can explain the observed temperature response. Higher organisms may have a more complicated behavioral response due to the simple fact that their motions have more degrees of freedom. Here we provide a principled analysis of motor behavior of such an organism -- the roundworm C. elegans. Using tracking video-microscopy we capture a worm's image and extract the skeleton of the shape as a head-to-tail ordered collection of tangent angles sampled along the curve. Applying principal components analysis we show that the space of shapes is remarkably low dimensional, with four dimensions accounting for > 95% of the shape variance. We also show that these dimensions align with behaviorally relevant states. As an application of this analysis we study the thermal response of worms stimulated by laser heating. Our quantitative description of C. elegans movement should prove useful in a wide variety of contexts, from the linking of motor output with neural circuitry to the genetic basis of adaptive behavior.

The N Terminus of Phosphodiesterase TbrPDEB1 of Trypanosoma brucei Contains the Signal for Integration into the Flagellar Skeleton ▿

PubMed Central

Luginbuehl, Edith; Ryter, Damaris; Schranz-Zumkehr, Judith; Oberholzer, Michael; Kunz, Stefan; Seebeck, Thomas

2010-01-01

The precise subcellular localization of the components of the cyclic AMP (cAMP) signaling pathways is a crucial aspect of eukaryotic intracellular signaling. In the human pathogen Trypanosoma brucei, the strict control of cAMP levels by cAMP-specific phosphodiesterases is essential for parasite survival, both in cell culture and in the infected host. Among the five cyclic nucleotide phosphodiesterases identified in this organism, two closely related isoenzymes, T. brucei PDEB1 (TbrPDEB1) (PDEB1) and TbrPDEB2 (PDEB2) are predominantly responsible for the maintenance of cAMP levels. Despite their close sequence similarity, they are distinctly localized in the cell. PDEB1 is mostly located in the flagellum, where it forms an integral part of the flagellar skeleton. PDEB2 is mainly located in the cell body, and only a minor part of the protein localizes to the flagellum. The current study, using transfection of procyclic trypanosomes with green fluorescent protein (GFP) reporters, demonstrates that the N termini of the two enzymes are essential for determining their final subcellular localization. The first 70 amino acids of PDEB1 are sufficient to specifically direct a GFP reporter to the flagellum and to lead to its detergent-resistant integration into the flagellar skeleton. In contrast, the analogous region of PDEB2 causes the GFP reporter to reside predominantly in the cell body. Mutagenesis of selected residues in the N-terminal region of PDEB2 demonstrated that single amino acid changes are sufficient to redirect the reporter from a cell body location to stable integration into the flagellar skeleton. PMID:20693305

Once more on the equilibrium-point hypothesis (lambda model) for motor control.

PubMed

Feldman, A G

1986-03-01

The equilibrium control hypothesis (lambda model) is considered with special reference to the following concepts: (a) the length-force invariant characteristic (IC) of the muscle together with central and reflex systems subserving its activity; (b) the tonic stretch reflex threshold (lambda) as an independent measure of central commands descending to alpha and gamma motoneurons; (c) the equilibrium point, defined in terms of lambda, IC and static load characteristics, which is associated with the notion that posture and movement are controlled by a single mechanism; and (d) the muscle activation area (a reformulation of the "size principle")--the area of kinematic and command variables in which a rank-ordered recruitment of motor units takes place. The model is used for the interpretation of various motor phenomena, particularly electromyographic patterns. The stretch reflex in the lambda model has no mechanism to follow-up a certain muscle length prescribed by central commands. Rather, its task is to bring the system to an equilibrium, load-dependent position. Another currently popular version defines the equilibrium point concept in terms of alpha motoneuron activity alone (the alpha model). Although the model imitates (as does the lambda model) spring-like properties of motor performance, it nevertheless is inconsistent with a substantial data base on intact motor control. An analysis of alpha models, including their treatment of motor performance in deafferented animals, reveals that they suffer from grave shortcomings. It is concluded that parameterization of the stretch reflex is a basis for intact motor control. Muscle deafferentation impairs this graceful mechanism though it does not remove the possibility of movement.

Should the injured and intact hemispheres be treated differently during the early phases of physical restorative therapy in experimental stroke or parkinsonism?

PubMed

Schallert, Tim; Fleming, Sheila M; Woodlee, Martin T

2003-02-01

Over a century ago the intact cortex was proposed to contribute to recovery from unilateral brain injury, but its possible role in functional outcome has become more appreciated in recent years as a result of anatomic, metabolic and behavioral studies. Although use of the contralesional limb is naturally impaired after sensorimotor cortex injury, neural and astrocytic events in the intact hemisphere may give rise to, and may be influenced by, an enhanced ability to compensate for lost motor function. The debate is still open as to whether the neural changes are generally compensatory in nature, with activity in the homotopic cortex leading to greater capability in the nonimpaired limb, or whether they are actually a matter of reorganization in the homotopic cortex leading to connections to denervated targets in the opposite hemisphere, thus allowing the homotopic cortex to control motor programs there. Although both phenomena may occur to some degree, there is mounting evidence in support of the former view. Careful behavioral techniques have been developed that can expose compensatory tricks, and the time course of these behaviors correlates well with anatomic data. Moreover, if the intact cortex sustains a second lesion after recovery from the first, forelimb sensorimotor function specific to the first-impaired side of the body is not worsened. Partial denervation of callosal fibers coming from the injured hemisphere, plus preferential use of the good forelimb caused by a cortical injury, may increase trophic factors in the intact hemisphere. These and related events seem to provide a growth-favorable environment there that permits motor learning in the intact forelimb at a level of skill exceeding that which a normal animal can attain in the same period of time. There are anecdotal cases in human neurologic patients that are consistent with these findings. For example, a colleague of the authors who sustained a unilateral infarction that rendered his dominant

Positive Youth Development, Life Satisfaction, and Problem Behaviors of Adolescents in Intact and Non-Intact Families in Hong Kong

PubMed Central

Shek, Daniel T. L.; Leung, Hildie

2013-01-01

This study investigated whether Chinese adolescents living in intact and non-intact families differed in their positive development, life satisfaction, and risk behavior. A total of 3,328 Secondary 1 students responded to measures of positive youth development (such as resilience and psychosocial competencies), life satisfaction, and risk behavior (substance abuse, delinquency, Internet addiction, consumption of pornographic materials, self-harm, and behavioral intention to engage in problem behavior). Findings revealed that adolescents growing up in intact families reported higher levels of positive developmental outcomes and life satisfaction as compared with adolescents from non-intact families. Adolescents in non-intact families also reported higher levels of risk behaviors than those growing up in intact families. PMID:24400264

Positive youth development, life satisfaction, and problem behaviors of adolescents in intact and non-intact families in Hong Kong.

PubMed

Shek, Daniel T L; Leung, Hildie

2013-01-01

This study investigated whether Chinese adolescents living in intact and non-intact families differed in their positive development, life satisfaction, and risk behavior. A total of 3,328 Secondary 1 students responded to measures of positive youth development (such as resilience and psychosocial competencies), life satisfaction, and risk behavior (substance abuse, delinquency, Internet addiction, consumption of pornographic materials, self-harm, and behavioral intention to engage in problem behavior). Findings revealed that adolescents growing up in intact families reported higher levels of positive developmental outcomes and life satisfaction as compared with adolescents from non-intact families. Adolescents in non-intact families also reported higher levels of risk behaviors than those growing up in intact families.

Is the Cerebellum Involved in Motor and Perceptual Timing: A Case Study.

DTIC Science & Technology

1985-05-15

return to regular employment as a typist. *The visual fields and cranial nerves were intact. The extraocular movements wererfull and there was no nystagmus ...Her saccades were hypermetric, especially on gaze to the left. Examination of motor function in the upper extremities revealed normal strength

Motor Control of Human Spinal Cord Disconnected from the Brain and Under External Movement.

PubMed

Mayr, Winfried; Krenn, Matthias; Dimitrijevic, Milan R

2016-01-01

Motor control after spinal cord injury is strongly depending on residual ascending and descending pathways across the lesion. The individually altered neurophysiology is in general based on still intact sublesional control loops with afferent sensory inputs linked via interneuron networks to efferent motor outputs. Partial or total loss of translesional control inputs reduces and alters the ability to perform voluntary movements and results in motor incomplete (residual voluntary control of movement functions) or motor complete (no residual voluntary control) spinal cord injury classification. Of particular importance are intact functionally silent neural structures with residual brain influence but reduced state of excitability that inhibits execution of voluntary movements. The condition is described by the term discomplete spinal cord injury. There are strong evidences that artificial afferent input, e.g., by epidural or noninvasive electrical stimulation of the lumbar posterior roots, can elevate the state of excitability and thus re-enable or augment voluntary movement functions. This modality can serve as a powerful assessment technique for monitoring details of the residual function profile after spinal cord injury, as a therapeutic tool for support of restoration of movement programs and as a neuroprosthesis component augmenting and restoring movement functions, per se or in synergy with classical neuromuscular or muscular electrical stimulation.

Exploratory investigations of hypervelocity intact capture spectroscopy

NASA Technical Reports Server (NTRS)

Tsou, P.; Griffiths, D. J.

1993-01-01

The ability to capture hypervelocity projectiles intact opens a new technique available for hypervelocity research. A determination of the reactions taking place between the projectile and the capture medium during the process of intact capture is extremely important to an understanding of the intact capture phenomenon, to improving the capture technique, and to developing a theory describing the phenomenon. The intact capture of hypervelocity projectiles by underdense media generates spectra, characteristic of the material species of projectile and capture medium involved. Initial exploratory results into real-time characterization of hypervelocity intact capture techniques by spectroscopy include ultra-violet and visible spectra obtained by use of reflecting gratings, transmitting gratings, and prisms, and recorded by photographic and electronic means. Spectrometry proved to be a valuable real-time diagnostic tool for hypervelocity intact capture events, offering understanding of the interactions of the projectile and the capture medium during the initial period and providing information not obtainable by other characterizations. Preliminary results and analyses of spectra produced by the intact capture of hypervelocity aluminum spheres in polyethylene (PE), polystyrene (PS), and polyurethane (PU) foams are presented. Included are tentative emission species identifications, as well as gray body temperatures produced in the intact capture process.

Computer simulation of flagellar movement VIII: coordination of dynein by local curvature control can generate helical bending waves.

PubMed

Brokaw, Charles J

2002-10-01

Computer simulations have been carried out with a model flagellum that can bend in three dimensions. A pattern of dynein activation in which regions of dynein activity propagate along each doublet, with a phase shift of approximately 1/9 wavelength between adjacent doublets, will produce a helical bending wave. This pattern can be termed "doublet metachronism." The simulations show that doublet metachronism can arise spontaneously in a model axoneme in which activation of dyneins is controlled locally by the curvature of each outer doublet microtubule. In this model, dyneins operate both as sensors of curvature and as motors. Doublet metachronism and the chirality of the resulting helical bending pattern are regulated by the angular difference between the direction of the moment and sliding produced by dyneins on a doublet and the direction of the controlling curvature for that doublet. A flagellum that is generating a helical bending wave experiences twisting moments when it moves against external viscous resistance. At high viscosities, helical bending will be significantly modified by twist unless the twist resistance is greater than previously estimated. Spontaneous doublet metachronism must be modified or overridden in order for a flagellum to generate the planar bending waves that are required for efficient propulsion of spermatozoa. Planar bending can be achieved with the three-dimensional flagellar model by appropriate specification of the direction of the controlling curvature for each doublet. However, experimental observations indicate that this "hard-wired" solution is not appropriate for real flagella. Copyright 2002 Wiley-Liss, Inc.

Scaling Equations for Ballistic Modeling of Solid Rocket Motor Case Breach

NASA Technical Reports Server (NTRS)

McMillin, Joshua E.

2006-01-01

This paper explores the development of a series of scaling equations that can take a known nominal motor performance and scale it for small and growing case failures. This model was developed for the Malfunction-Turn Study as part of Return to Flight activities for the Space Shuttle program. To verify the model, data from the Challenger accident (STS- 51L) were used. The model is able to predict the motor performance beyond the last recorded Challenger data and show how the failed right hand booster would have performed if the vehicle had remained intact.

[A new type of flagellar structure. Type 9+n

PubMed Central

1977-01-01

The ultrastructural study of the Eoacanthocephala sperm cell shows a variation from 0 to 5 in the number of the axial fibers in the axoneme. All the species of the order Eoacanthocephala available to us show this variation; moreover, every individual possesses simultaneously several different structural types. So, we are dealing with a new flagellar organization: 9+n, with 0 less than or equal to n less than or equal to 5. In the Quadrigyridae and the Tenuisentidae families, n varies from 0 to 4, with a maximum of 2 for most individuals, exceptionally at 1 for some individuals. In the Neoechinorhynchidae family, n varies from 0 to 5 with a conspicuous prevalence of 3 (from 84 to 99%, according to the individual). These results prompted us to reexamine the two other orders of Acanthocephala in which the structural types 9+2 or 9+0 have been considered as fixed. Indeed, we have found a few flagella the structure of which is different from the prevalent one. It seems, therefore, that the number of the central fibers of the axoneme in the Acanthocephala sperm cell is never absolutely fixed. PMID:557042

Intact glycopeptide characterization using mass spectrometry.

PubMed

Cao, Li; Qu, Yi; Zhang, Zhaorui; Wang, Zhe; Prytkova, Iya; Wu, Si

2016-05-01

Glycosylation is one of the most prominent and extensively studied protein post-translational modifications. However, traditional proteomic studies at the peptide level (bottom-up) rarely characterize intact glycopeptides (glycosylated peptides without removing glycans), so no glycoprotein heterogeneity information is retained. Intact glycopeptide characterization, on the other hand, provides opportunities to simultaneously elucidate the glycan structure and the glycosylation site needed to reveal the actual biological function of protein glycosylation. Recently, significant improvements have been made in the characterization of intact glycopeptides, ranging from enrichment and separation, mass spectroscopy (MS) detection, to bioinformatics analysis. In this review, we recapitulated currently available intact glycopeptide characterization methods with respect to their advantages and limitations as well as their potential applications.

Flagellar membrane fusion and protein exchange in trypanosomes; a new form of cell-cell communication?

PubMed Central

Imhof, Simon; Fragoso, Cristina; Hemphill, Andrew; von Schubert, Conrad; Li, Dong; Legant, Wesley; Betzig, Eric; Roditi, Isabel

2016-01-01

Diverse structures facilitate direct exchange of proteins between cells, including plasmadesmata in plants and tunnelling nanotubes in bacteria and higher eukaryotes.  Here we describe a new mechanism of protein transfer, flagellar membrane fusion, in the unicellular parasite Trypanosoma brucei. When fluorescently tagged trypanosomes were co-cultured, a small proportion of double-positive cells were observed. The formation of double-positive cells was dependent on the presence of extracellular calcium and was enhanced by placing cells in medium supplemented with fresh bovine serum. Time-lapse microscopy revealed that double-positive cells arose by bidirectional protein exchange in the absence of nuclear transfer.  Furthermore, super-resolution microscopy showed that this process occurred in ≤1 minute, the limit of temporal resolution in these experiments. Both cytoplasmic and membrane proteins could be transferred provided they gained access to the flagellum. Intriguingly, a component of the RNAi machinery (Argonaute) was able to move between cells, raising the possibility that small interfering RNAs are transported as cargo. Transmission electron microscopy showed that shared flagella contained two axonemes and two paraflagellar rods bounded by a single membrane. In some cases flagellar fusion was partial and interactions between cells were transient. In other cases fusion occurred along the entire length of the flagellum, was stable for several hours and might be irreversible. Fusion did not appear to be deleterious for cell function: paired cells were motile and could give rise to progeny while fused. The motile flagella of unicellular organisms are related to the sensory cilia of higher eukaryotes, raising the possibility that protein transfer between cells via cilia or flagella occurs more widely in nature. PMID:27239276

Proteomics on the rims; insights into the biology of the nuclear envelope and flagellar pocket of trypanosomes

PubMed Central

Field, Mark C.; Adung’a, Vincent; Obado, Samson; Chait, Brian T.; Rout, Michael P.

2014-01-01

SUMMERY Trypanosomatids represent the causative agents of major diseases in humans, livestock and plants, with inevitable suffering and economic hardship as a result. They are also evolutionarily highly divergent organisms, and the many unique aspects of trypanosome biology provide opportunities in terms of identification of drug targets, the challenge of exploiting these putative targets, and at the same time significant scope for exploration of novel and divergent cell biology. We can estimate from genome sequences that the degree of divergence of trypanosomes from animals and fungi is extreme, with perhaps one third to one half of predicted trypanosome proteins having no known function based on homology or recognizable protein domains/architecture. Two highly important aspects of trypanosome biology are the flagellar pocket and the nuclear envelope, where in silico analysis clearly suggests great potential divergence in the proteome. The flagellar pocket is the sole site of endo- and exocytosis in trypanosomes and plays important roles in immune evasion via variant surface glycoprotein (VSG) trafficking and providing a location for sequestration of various invariant receptors. The trypanosome nuclear envelope has been largely unexplored, but by analogy with higher eukaryotes, roles in the regulation of chromatin and most significantly, in controlling VSG gene expression are expected. Here we discuss recent successful proteomics-based approaches towards characterization of the nuclear envelope and the endocytic apparatus, the identification of conserved and novel trypanosomatid-specific features, and the implications of these findings. PMID:22309600

Basic Timing Abilities Stay Intact in Patients with Musician's Dystonia

PubMed Central

van der Steen, M. C.; van Vugt, Floris T.; Keller, Peter E.; Altenmüller, Eckart

2014-01-01

Task-specific focal dystonia is a movement disorder that is characterized by the loss of voluntary motor control in extensively trained movements. Musician's dystonia is a type of task-specific dystonia that is elicited in professional musicians during instrumental playing. The disorder has been associated with deficits in timing. In order to test the hypothesis that basic timing abilities are affected by musician's dystonia, we investigated a group of patients (N = 15) and a matched control group (N = 15) on a battery of sensory and sensorimotor synchronization tasks. Results did not show any deficits in auditory-motor processing for patients relative to controls. Both groups benefited from a pacing sequence that adapted to their timing (in a sensorimotor synchronization task at a stable tempo). In a purely perceptual task, both groups were able to detect a misaligned metronome when it was late rather than early relative to a musical beat. Overall, the results suggest that basic timing abilities stay intact in patients with musician's dystonia. This supports the idea that musician's dystonia is a highly task-specific movement disorder in which patients are mostly impaired in tasks closely related to the demands of actually playing their instrument. PMID:24667273

The IntAct molecular interaction database in 2012

PubMed Central

Kerrien, Samuel; Aranda, Bruno; Breuza, Lionel; Bridge, Alan; Broackes-Carter, Fiona; Chen, Carol; Duesbury, Margaret; Dumousseau, Marine; Feuermann, Marc; Hinz, Ursula; Jandrasits, Christine; Jimenez, Rafael C.; Khadake, Jyoti; Mahadevan, Usha; Masson, Patrick; Pedruzzi, Ivo; Pfeiffenberger, Eric; Porras, Pablo; Raghunath, Arathi; Roechert, Bernd; Orchard, Sandra; Hermjakob, Henning

2012-01-01

IntAct is an open-source, open data molecular interaction database populated by data either curated from the literature or from direct data depositions. Two levels of curation are now available within the database, with both IMEx-level annotation and less detailed MIMIx-compatible entries currently supported. As from September 2011, IntAct contains approximately 275 000 curated binary interaction evidences from over 5000 publications. The IntAct website has been improved to enhance the search process and in particular the graphical display of the results. New data download formats are also available, which will facilitate the inclusion of IntAct's data in the Semantic Web. IntAct is an active contributor to the IMEx consortium (http://www.imexconsortium.org). IntAct source code and data are freely available at http://www.ebi.ac.uk/intact. PMID:22121220

Motor Decline in Clinically Presymptomatic Spinocerebellar Ataxia Type 2 Gene Carriers

PubMed Central

Velázquez-Perez, Luis; Díaz, Rosalinda; Pérez-González, Ruth; Canales, Nalia; Rodríguez-Labrada, Roberto; Medrano, Jacquelín; Sánchez, Gilberto; Almaguer-Mederos, Luis; Torres, Cira; Fernandez-Ruiz, Juan

2009-01-01

Background Motor deficits are a critical component of the clinical characteristics of patients with spinocerebellar ataxia type 2. However, there is no current information on the preclinical manifestation of those motor deficits in presymptomatic gene carriers. To further understand and characterize the onset of the clinical manifestation in this disease, we tested presymptomatic spinocerebellar ataxia type 2 gene carriers, and volunteers, in a task that evaluates their motor performance and their motor learning capabilities. Methods and Findings 28 presymptomatic spinocerebellar ataxia type 2 gene carriers and an equal number of control volunteers matched for age and gender participated in the study. Both groups were tested in a prism adaptation task known to be sensible to both motor performance and visuomotor learning deficits. Our results clearly show that although motor learning capabilities are intact, motor performance deficits are present even years before the clinical manifestation of the disease start. Conclusions The results show a clear deficit in motor performance that can be detected years before the clinical onset of the disease. This motor performance deficit appears before any motor learning or clinical manifestations of the disease. These observations identify the performance coefficient as an objective and quantitative physiological biomarker that could be useful to assess the efficiency of different therapeutic agents. PMID:19401771

50 CFR 622.381 - Landing fish intact.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Landing fish intact. 622.381 Section 622... Migratory Pelagic Resources (Gulf of Mexico and South Atlantic) § 622.381 Landing fish intact. (a) Cobia... head and fins intact. Such fish may be eviscerated, gilled, and scaled, but must otherwise be...

50 CFR 622.381 - Landing fish intact.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Landing fish intact. 622.381 Section 622... Migratory Pelagic Resources (Gulf of Mexico and South Atlantic) § 622.381 Landing fish intact. (a) Cobia... head and fins intact. Such fish may be eviscerated, gilled, and scaled, but must otherwise be...

50 CFR 622.276 - Landing fish intact.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Landing fish intact. 622.276 Section 622... Wahoo Fishery Off the Atlantic States § 622.276 Landing fish intact. (a) Dolphin and wahoo in or from the Atlantic EEZ must be maintained with head and fins intact. Such fish may be eviscerated, gilled...

50 CFR 622.276 - Landing fish intact.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Landing fish intact. 622.276 Section 622... Wahoo Fishery Off the Atlantic States § 622.276 Landing fish intact. (a) Dolphin and wahoo in or from the Atlantic EEZ must be maintained with head and fins intact. Such fish may be eviscerated, gilled...

50 CFR 622.38 - Landing fish intact.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 12 2012-10-01 2012-10-01 false Landing fish intact. 622.38 Section 622... § 622.38 Landing fish intact. The operator of a vessel that fishes in the EEZ is responsible for ensuring that fish on that vessel in the EEZ are maintained intact and, if taken from the EEZ, are...

50 CFR 622.38 - Landing fish intact.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false Landing fish intact. 622.38 Section 622... § 622.38 Landing fish intact. The operator of a vessel that fishes in the EEZ is responsible for ensuring that fish on that vessel in the EEZ are maintained intact and, if taken from the EEZ, are...

Novel Membrane-Bound eIF2α Kinase in the Flagellar Pocket of Trypanosoma brucei▿

PubMed Central

Moraes, Maria Carolina S.; Jesus, Teresa C. L.; Hashimoto, Nilce N.; Dey, Madhusudan; Schwartz, Kevin J.; Alves, Viviane S.; Avila, Carla C.; Bangs, James D.; Dever, Thomas E.; Schenkman, Sergio; Castilho, Beatriz A.

2007-01-01

Translational control mediated by phosphorylation of the alpha subunit of the eukaryotic initiation factor 2 (eIF2α) is central to stress-induced programs of gene expression. Trypanosomatids, important human pathogens, display differentiation processes elicited by contact with the distinct physiological milieu found in their insect vectors and mammalian hosts, likely representing stress situations. Trypanosoma brucei, the agent of African trypanosomiasis, encodes three potential eIF2α kinases (TbeIF2K1 to -K3). We show here that TbeIF2K2 is a transmembrane glycoprotein expressed both in procyclic and in bloodstream forms. The catalytic domain of TbeIF2K2 phosphorylates yeast and mammalian eIF2α at Ser51. It also phosphorylates the highly unusual form of eIF2α found in trypanosomatids specifically at residue Thr169 that corresponds to Ser51 in other eukaryotes. T. brucei eIF2α, however, is not a substrate for GCN2 or PKR in vitro. The putative regulatory domain of TbeIF2K2 does not share any sequence similarity with known eIF2α kinases. In both procyclic and bloodstream forms TbeIF2K2 is mainly localized in the membrane of the flagellar pocket, an organelle that is the exclusive site of exo- and endocytosis in these parasites. It can also be detected in endocytic compartments but not in lysosomes, suggesting that it is recycled between endosomes and the flagellar pocket. TbeIF2K2 location suggests a relevance in sensing protein or nutrient transport in T. brucei, an organism that relies heavily on posttranscriptional regulatory mechanisms to control gene expression in different environmental conditions. This is the first membrane-associated eIF2α kinase described in unicellular eukaryotes. PMID:17873083

A macroscopic scale model of bacterial flagellar bundling

NASA Astrophysics Data System (ADS)

Kim, Munju; Bird, James C.; van Parys, Annemarie J.; Breuer, Kenneth S.; Powers, Thomas R.

2003-12-01

Escherichia coli and other bacteria use rotating helical filaments to swim. Each cell typically has about four filaments, which bundle or disperse depending on the sense of motor rotation. To study the bundling process, we built a macroscopic scale model consisting of stepper motor-driven polymer helices in a tank filled with a high-viscosity silicone oil. The Reynolds number, the ratio of viscous to elastic stresses, and the helix geometry of our experimental model approximately match the corresponding quantities of the full-scale E. coli cells. We analyze digital video images of the rotating helices to show that the initial rate of bundling is proportional to the motor frequency and is independent of the characteristic relaxation time of the filament. We also determine which combinations of helix handedness and sense of motor rotation lead to bundling.

Comparison of independent screens on differentially vulnerable motor neurons reveals alpha-synuclein as a common modifier in motor neuron diseases.

PubMed

Kline, Rachel A; Kaifer, Kevin A; Osman, Erkan Y; Carella, Francesco; Tiberi, Ariana; Ross, Jolill; Pennetta, Giuseppa; Lorson, Christian L; Murray, Lyndsay M

2017-03-01

The term "motor neuron disease" encompasses a spectrum of disorders in which motor neurons are the primary pathological target. However, in both patients and animal models of these diseases, not all motor neurons are equally vulnerable, in that while some motor neurons are lost very early in disease, others remain comparatively intact, even at late stages. This creates a valuable system to investigate the factors that regulate motor neuron vulnerability. In this study, we aim to use this experimental paradigm to identify potential transcriptional modifiers. We have compared the transcriptome of motor neurons from healthy wild-type mice, which are differentially vulnerable in the childhood motor neuron disease Spinal Muscular Atrophy (SMA), and have identified 910 transcriptional changes. We have compared this data set with published microarray data sets on other differentially vulnerable motor neurons. These neurons were differentially vulnerable in the adult onset motor neuron disease Amyotrophic Lateral Sclerosis (ALS), but the screen was performed on the equivalent population of neurons from neurologically normal human, rat and mouse. This cross species comparison has generated a refined list of differentially expressed genes, including CELF5, Col5a2, PGEMN1, SNCA, Stmn1 and HOXa5, alongside a further enrichment for synaptic and axonal transcripts. As an in vivo validation, we demonstrate that the manipulation of a significant number of these transcripts can modify the neurodegenerative phenotype observed in a Drosophila line carrying an ALS causing mutation. Finally, we demonstrate that vector-mediated expression of alpha-synuclein (SNCA), a transcript decreased in selectively vulnerable motor neurons in all four screens, can extend life span, increase weight and decrease neuromuscular junction pathology in a mouse model of SMA. In summary, we have combined multiple data sets to identify transcripts, which are strong candidates for being phenotypic modifiers

Development of Second Generation Intact Stability Criteria

DTIC Science & Technology

2011-12-01

the intact stability performance of ships, have motivated the development of the second generation intact stability criteria by the IMO Subcommittee on...primary modes of stability failures which are being addressed. The second generation intact stability criteria are planned to have a multitiered structure...and 2 vulnerability criteria that are used as a preliminary design process check of dynamic stability failure risk. This report describes the U.S

Sleep benefits consolidation of visuo-motor adaptation learning in older adults.

PubMed

Mantua, Janna; Baran, Bengi; Spencer, Rebecca M C

2016-02-01

Sleep is beneficial for performance across a range of memory tasks in young adults, but whether memories are similarly consolidated in older adults is less clear. Performance benefits have been observed following sleep in older adults for declarative learning tasks, but this benefit may be reduced for non-declarative, motor skill learning tasks. To date, studies of sleep-dependent consolidation of motor learning in older adults are limited to motor sequence tasks. To examine whether reduced sleep-dependent consolidation in older adults is generalizable to other forms of motor skill learning, we examined performance changes over intervals of sleep and wake in young (n = 62) and older adults (n = 61) using a mirror-tracing task, which assesses visuo-motor adaptation learning. Participants learned the task either in the morning or in evening, and performance was assessed following a 12-h interval containing overnight sleep or daytime wake. Contrary to our prediction, both young adults and older adults exhibited sleep-dependent gains in visuo-motor adaptation. There was a correlation between performance improvement over sleep and percent of the night in non-REM stage 2 sleep. These results indicate that motor skill consolidation remains intact with increasing age although this relationship may be limited to specific forms of motor skill learning.

Prolyl hydroxylase regulates axonal rewiring and motor recovery after traumatic brain injury

PubMed Central

Miyake, S; Muramatsu, R; Hamaguchi, M; Yamashita, T

2015-01-01

Prolyl 4-hydroxylases (PHDs; PHD1, PHD2, and PHD3) are a component of cellular oxygen sensors that regulate the adaptive response depending on the oxygen concentration stabilized by hypoxia/stress-regulated genes transcription. In normoxic condition, PHD2 is required to stabilize hypoxia inducible factors. Silencing of PHD2 leads to the activation of intracellular signaling including RhoA and Rho-associated protein kinase (ROCK), which are key regulators of neurite growth. In this study, we determined that genetic or pharmacological inhibition of PHD2 in cultured cortical neurons prevents neurite elongation through a ROCK-dependent mechanism. We then explored the role of PHDs in axonal reorganization following a traumatic brain injury in adult mice. Unilateral destruction of motor cortex resulted in behavioral deficits due to disruption of the corticospinal tract (CST), a part of the descending motor pathway. In the spinal cord, sprouting of fibers from the intact side of the CST into the denervated side is thought to contribute to the recovery process following an injury. Intracortical infusion of PHD inhibitors into the intact side of the motor cortex abrogated spontaneous formation of CST collaterals and functional recovery after damage to the sensorimotor cortex. These findings suggest PHDs have an important role in the formation of compensatory axonal networks following an injury and may represent a new molecular target for the central nervous system disorders. PMID:25675298

Electromyographic studies of motor control in humans.

PubMed

Shahani, B T; Wierzbicka, M M

1987-11-01

Electromyography and electroneurography have proved to be useful in investigation and understanding of a variety of neurologic disorders. In most laboratories, however, these electrodiagnostic techniques have been used to help in the diagnosis of diseases that affect the peripheral nerves, neuromuscular junctions, or skeletal muscle fibers. Although major advances in electronic and computer technology have made it possible to study, quantitate, and document reflex activity in intact human subjects, most neurologists still rely on gross clinical observations and most electromyographers continue to use conventional techniques of EMG and nerve conduction studies to differentiate "myopathy" from "neuropathy." This article is a review of some of the electromyographic techniques that have been used in the authors' laboratory for the study of normal and abnormal motor control in man and the treatment of patients with disorders of motor control.

Coordination of Fictive Motor Activity in the Larval Zebrafish Is Generated by Non-Segmental Mechanisms

PubMed Central

Wiggin, Timothy D.; Peck, Jack H.; Masino, Mark A.

2014-01-01

The cellular and network basis for most vertebrate locomotor central pattern generators (CPGs) is incompletely characterized, but organizational models based on known CPG architectures have been proposed. Segmental models propose that each spinal segment contains a circuit that controls local coordination and sends longer projections to coordinate activity between segments. Unsegmented/continuous models propose that patterned motor output is driven by gradients of neurons and synapses that do not have segmental boundaries. We tested these ideas in the larval zebrafish, an animal that swims in discrete episodes, each of which is composed of coordinated motor bursts that progress rostrocaudally and alternate from side to side. We perturbed the spinal cord using spinal transections or strychnine application and measured the effect on fictive motor output. Spinal transections eliminated episode structure, and reduced both rostrocaudal and side-to-side coordination. Preparations with fewer intact segments were more severely affected, and preparations consisting of midbody and caudal segments were more severely affected than those consisting of rostral segments. In reduced preparations with the same number of intact spinal segments, side-to-side coordination was more severely disrupted than rostrocaudal coordination. Reducing glycine receptor signaling with strychnine reversibly disrupted both rostrocaudal and side-to-side coordination in spinalized larvae without disrupting episodic structure. Both spinal transection and strychnine decreased the stability of the motor rhythm, but this effect was not causal in reducing coordination. These results are inconsistent with a segmented model of the spinal cord and are better explained by a continuous model in which motor neuron coordination is controlled by segment-spanning microcircuits. PMID:25275377

A conserved residue, PomB-F22, in the transmembrane segment of the flagellar stator complex, has a critical role in conducting ions and generating torque.

PubMed

Terauchi, Takashi; Terashima, Hiroyuki; Kojima, Seiji; Homma, Michio

2011-08-01

Bacterial flagellar motors exploit the electrochemical potential gradient of a coupling ion (H(+) or Na(+)) as their energy source, and are composed of stator and rotor proteins. Sodium-driven and proton-driven motors have the stator proteins PomA and PomB or MotA and MotB, respectively, which interact with each other in their transmembrane (TM) regions to form an ion channel. The single TM region of PomB or MotB, which forms the ion-conduction pathway together with TM3 and TM4 of PomA or MotA, respectively, has a highly conserved aspartate residue that is the ion binding site and is essential for rotation. To investigate the ion conductivity and selectivity of the Na(+)-driven PomA/PomB stator complex, we replaced conserved residues predicted to be near the conserved aspartate with H(+)-type residues, PomA-N194Y, PomB-F22Y and/or PomB-S27T. Motility analysis revealed that the ion specificity was not changed by either of the PomB mutations. PomB-F22Y required a higher concentration of Na(+) to exhibit swimming, but this effect was suppressed by additional mutations, PomA-N194Y or PomB-S27T. Moreover, the motility of the PomB-F22Y mutant was resistant to phenamil, a specific inhibitor for the Na(+) channel. When PomB-F22 was changed to other amino acids and the effects on swimming ability were investigated, replacement with a hydrophilic residue decreased the maximum swimming speed and conferred strong resistance to phenamil. From these results, we speculate that the Na(+) flux is reduced by the PomB-F22Y mutation, and that PomB-F22 is important for the effective release of Na(+) from PomB-D24.

Central command differentially affects aortic and carotid sinus baroreflexes at the onset of spontaneous motor activity.

PubMed

Matsukawa, Kanji; Ishii, Kei; Idesako, Mitsuhiro; Ishida, Tomoko; Endo, Kana; Liang, Nan

2013-12-01

Our laboratory has recently demonstrated that central command provides selective inhibition of the cardiomotor component of aortic (AOR) baroreflex during exercise, preserving carotid sinus (CS) baroreflex. To further explore the differential effects of central command on the arterial baroreflexes, we surgically separated the AOR and CS baroreflex systems, to identify the input-output relationship of each baroreflex system using brief occlusion of the abdominal aorta in decerebrate cats. Baroreflex sensitivity for heart rate (HR) was estimated from the baroreflex ratio between the pressor and bradycardia responses during aortic occlusion and from the slope of the baroreflex curve between the changes in mean arterial blood pressure (ΔMAP) and ΔHR. Spontaneous motor activity accompanied the abrupt increases in HR and MAP. When aortic occlusion was given at the onset of spontaneous motor activity, the baroreflex ratio was blunted to 11-25% of the preexercise value in either intact or AOR baroreflex. The slope of the ΔMAP-ΔHR curve was similarly attenuated at the onset of spontaneous motor activity to 11-18% of the slope during the preexercise period. In contrast, in the CS baroreflex, the baroreflex ratio and curve slope were not significantly (P>0.05) altered by spontaneous motor activity. An upward shift of the baroreflex curve appeared at the onset of spontaneous motor activity, irrespective of the intact, AOR, and CS baroreflex conditions. Taken together, it is concluded that central command provides selective inhibition for the cardiomotor limb of the aortic baroreflex at the onset of exercise, which in turn contributes to an instantaneous increase in HR. © 2013.

Comparison of independent screens on differentially vulnerable motor neurons reveals alpha-synuclein as a common modifier in motor neuron diseases

PubMed Central

Kaifer, Kevin A.; Osman, Erkan Y.; Carella, Francesco; Tiberi, Ariana; Ross, Jolill; Pennetta, Giuseppa; Lorson, Christian L.

2017-01-01

The term “motor neuron disease” encompasses a spectrum of disorders in which motor neurons are the primary pathological target. However, in both patients and animal models of these diseases, not all motor neurons are equally vulnerable, in that while some motor neurons are lost very early in disease, others remain comparatively intact, even at late stages. This creates a valuable system to investigate the factors that regulate motor neuron vulnerability. In this study, we aim to use this experimental paradigm to identify potential transcriptional modifiers. We have compared the transcriptome of motor neurons from healthy wild-type mice, which are differentially vulnerable in the childhood motor neuron disease Spinal Muscular Atrophy (SMA), and have identified 910 transcriptional changes. We have compared this data set with published microarray data sets on other differentially vulnerable motor neurons. These neurons were differentially vulnerable in the adult onset motor neuron disease Amyotrophic Lateral Sclerosis (ALS), but the screen was performed on the equivalent population of neurons from neurologically normal human, rat and mouse. This cross species comparison has generated a refined list of differentially expressed genes, including CELF5, Col5a2, PGEMN1, SNCA, Stmn1 and HOXa5, alongside a further enrichment for synaptic and axonal transcripts. As an in vivo validation, we demonstrate that the manipulation of a significant number of these transcripts can modify the neurodegenerative phenotype observed in a Drosophila line carrying an ALS causing mutation. Finally, we demonstrate that vector-mediated expression of alpha-synuclein (SNCA), a transcript decreased in selectively vulnerable motor neurons in all four screens, can extend life span, increase weight and decrease neuromuscular junction pathology in a mouse model of SMA. In summary, we have combined multiple data sets to identify transcripts, which are strong candidates for being phenotypic

Neural Substrates for the Effects of Rehabilitative Training on Motor Recovery After Ischemic Infarct

NASA Astrophysics Data System (ADS)

Nudo, Randolph J.; Wise, Birute M.; Sifuentes, Frank; Milliken, Garrett W.

1996-06-01

Substantial functional reorganization takes place in the motor cortex of adult primates after a focal ischemic infarct, as might occur in stroke. A subtotal lesion confined to a small portion of the representation of one hand was previously shown to result in a further loss of hand territory in the adjacent, undamaged cortex of adult squirrel monkeys. In the present study, retraining of skilled hand use after similar infarcts resulted in prevention of the loss of hand territory adjacent to the infarct. In some instances, the hand representations expanded into regions formerly occupied by representations of the elbow and shoulder. Functional reorganization in the undamaged motor cortex was accompanied by behavioral recovery of skilled hand function. These results suggest that, after local damage to the motor cortex, rehabilitative training can shape subsequent reorganization in the adjacent intact cortex, and that the undamaged motor cortex may play an important role in motor recovery.

In Vivo Neuromechanics: Decoding Causal Motor Neuron Behavior with Resulting Musculoskeletal Function.

PubMed

Sartori, Massimo; Yavuz, Utku Ş; Farina, Dario

2017-10-18

Human motor function emerges from the interaction between the neuromuscular and the musculoskeletal systems. Despite the knowledge of the mechanisms underlying neural and mechanical functions, there is no relevant understanding of the neuro-mechanical interplay in the neuro-musculo-skeletal system. This currently represents the major challenge to the understanding of human movement. We address this challenge by proposing a paradigm for investigating spinal motor neuron contribution to skeletal joint mechanical function in the intact human in vivo. We employ multi-muscle spatial sampling and deconvolution of high-density fiber electrical activity to decode accurate α-motor neuron discharges across five lumbosacral segments in the human spinal cord. We use complete α-motor neuron discharge series to drive forward subject-specific models of the musculoskeletal system in open-loop with no corrective feedback. We perform validation tests where mechanical moments are estimated with no knowledge of reference data over unseen conditions. This enables accurate blinded estimation of ankle function purely from motor neuron information. Remarkably, this enables observing causal associations between spinal motor neuron activity and joint moment control. We provide a new class of neural data-driven musculoskeletal modeling formulations for bridging between movement neural and mechanical levels in vivo with implications for understanding motor physiology, pathology, and recovery.

Motor control and the management of musculoskeletal dysfunction.

PubMed

van Vliet, Paulette M; Heneghan, Nicola R

2006-08-01

This paper aims to develop understanding of three important motor control issues--feedforward mechanisms, cortical plasticity and task-specificity and assess the implications for musculoskeletal practice. A model of control for the reach-to-grasp movement illustrates how the central nervous system integrates sensorimotor processes to control complex movements. Feedforward mechanisms, an essential element of motor control, are altered in neurologically intact patients with chronic neck pain and low back pain. In healthy subjects, cortical mapping studies using transcranial magnetic stimulation have demonstrated that neural pathways adapt according to what and how much is practised. Neuroplasticity has also been demonstrated in a number of musculoskeletal conditions, where cortical maps are altered compared to normal. Behavioural and neurophysiological studies indicate that environmental and task constraints such as the goal of the task and an object's shape and size, are determinants of the motor schema for reaching and other movements. Consideration of motor control issues as well as signs and symptoms, may facilitate management of musculoskeletal conditions and improve outcome. Practice of entire everyday tasks at an early stage and systematic variation of the task is recommended. Training should be directed with the aim of re-educating feedforward mechanisms where necessary and the amount of practice should be sufficient to cause changes in cortical activity.

[Trigeminal motor paralysis and dislocation of the temporo-mandibular joints].

PubMed

Ohkawa, S; Yoshida, T; Ohsumi, Y; Tabuchi, M

1996-07-01

A 64-year-old woman with diabetes mellitus was admitted to our hospital with left hemiparesis of sudden onset. A brain MRI demonstrated a cerebral infarction in the ventral part of the right lower pons. When left hemiparesis worsened, she had dislocation of the temporo-mandibular joints repeatedly. Then, her lower jaw deviated to the right when she opened her mouth. Also, there was decreased contraction of the right masseter when she clenched her teeth. These findings suggest that there was trigeminal motor paralysis on the right side resulting from involvement of the intrapontine trigeminal motor nerve. She has no history of dislocation of the temporo-mandibular joints. An X-ray film showed that the temporo-mandibular joints were intact. Thus, it is possible that deviation of the lower jaw was the cause of this dislocation. We suspect that dislocation of the temporo-mandibular joints may occur as a complication of unilateral trigeminal motor paralysis. This has not been reported to our knowledge.

Dopamine D1 receptor activation maintains motor coordination in injured rats but does not accelerate the recovery of the motor coordination deficit.

PubMed

Avila-Luna, Alberto; Gálvez-Rosas, Arturo; Alfaro-Rodríguez, Alfonso; Reyes-Legorreta, Celia; Garza-Montaño, Paloma; González-Piña, Rigoberto; Bueno-Nava, Antonio

2018-01-15

The sensorimotor cortex and the striatum are interconnected by the corticostriatal pathway, suggesting that cortical injury alters the striatal function that is associated with skilled movements and motor learning, which are functions that may be modulated by dopamine (DA). In this study, we explored motor coordination and balance in order to investigate whether the activation of D 1 receptors (D 1 Rs) modulates functional recovery after cortical injury. The results of the beam-walking test showed motor deficit in the injured group at 24, 48 and 96h post-injury, and the recovery time was observed at 192h after cortical injury. In the sham and injured rats, systemic administration of the D 1 R antagonist SCH-23390 (1mg/kg) alone at 24, 48, 96 and 192h significantly (P<0.01) increased the motor deficit, while administration of the D 1 R agonist SKF-38393 alone (2, 3 and 4mg/kg) at 24, 48, 96 and 192h post-injury did not produce a significant difference; however, the co-administration of SKF-38393 and SCH-23390 prevented the antagonist-induced increase in the motor deficit. The cortical+striatal injury showed significantly increased the motor deficit at 24, 48, 96 and 192h post-injury (P<0.01) but did not show recovery at 192h. In conclusion, the administration of the D 1 R agonist did not accelerate the motor recovery, but the activation of D 1 Rs maintained motor coordination, confirming that an intact striatum may be necessary for achieving recovery. Copyright © 2017 Elsevier B.V. All rights reserved.

46 CFR 28.570 - Intact righting energy.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 1 2014-10-01 2014-10-01 false Intact righting energy. 28.570 Section 28.570 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY UNINSPECTED VESSELS REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS Stability § 28.570 Intact righting energy. (a) Except as provided in paragraph (c) of this...

46 CFR 28.570 - Intact righting energy.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 1 2012-10-01 2012-10-01 false Intact righting energy. 28.570 Section 28.570 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY UNINSPECTED VESSELS REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS Stability § 28.570 Intact righting energy. (a) Except as provided in paragraph (c) of this...

46 CFR 28.570 - Intact righting energy.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Intact righting energy. 28.570 Section 28.570 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY UNINSPECTED VESSELS REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS Stability § 28.570 Intact righting energy. (a) Except as provided in paragraph (c) of this...

46 CFR 28.570 - Intact righting energy.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 1 2011-10-01 2011-10-01 false Intact righting energy. 28.570 Section 28.570 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY UNINSPECTED VESSELS REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS Stability § 28.570 Intact righting energy. (a) Except as provided in paragraph (c) of this...

46 CFR 28.570 - Intact righting energy.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 1 2013-10-01 2013-10-01 false Intact righting energy. 28.570 Section 28.570 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY UNINSPECTED VESSELS REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS Stability § 28.570 Intact righting energy. (a) Except as provided in paragraph (c) of this...

Small Particles Intact Capture Experiment (SPICE)

NASA Technical Reports Server (NTRS)

Nishioka, Ken-Ji; Carle, G. C.; Bunch, T. E.; Mendez, David J.; Ryder, J. T.

1994-01-01

The Small Particles Intact Capture Experiment (SPICE) will develop technologies and engineering techniques necessary to capture nearly intact, uncontaminated cosmic and interplanetary dust particles (IDP's). Successful capture of such particles will benefit the exobiology and planetary science communities by providing particulate samples that may have survived unaltered since the formation of the solar system. Characterization of these particles may contribute fundamental data to our knowledge of how these particles could have formed into our planet Earth and, perhaps, contributed to the beginnings of life. The term 'uncontaminated' means that captured cosmic and IDP particles are free of organic contamination from the capture process and the term 'nearly intact capture' means that their chemical and elemental components are not materially altered during capture. The key to capturing cosmic and IDP particles that are organic-contamination free and nearly intact is the capture medium. Initial screening of capture media included organic foams, multiple thin foil layers, and aerogel (a silica gel); but, with the exception of aerogel, the requirements of no contamination or nearly intact capture were not met. To ensure no contamination of particles in the capture process, high-purity aerogel was chosen. High-purity aerogel results in high clarity (visual clearness), a useful quality in detection and recovery of embedded captured particles from the aerogel. P. Tsou at the Jet Propulsion Laboratory (JPL) originally described the use of aerogel for this purpose and reported laboratory test results. He has flown aerogel as a 'GAS-can Lid' payload on STS-47 and is evaluating the results. The Timeband Capture Cell Experiment (TICCE), a Eureca 1 experiment, is also flying aerogel and is scheduled for recovery in late April.

Structural and molecular conformation of myosin in intact muscle fibers by second harmonic generation

NASA Astrophysics Data System (ADS)

Nucciotti, V.; Stringari, C.; Sacconi, L.; Vanzi, F.; Linari, M.; Piazzesi, G.; Lombardi, V.; Pavone, F. S.

2009-02-01

Recently, the use of Second Harmonic Generation (SHG) for imaging biological samples has been explored with regard to intrinsic SHG in highly ordered biological samples. As shown by fractional extraction of proteins, myosin is the source of SHG signal in skeletal muscle. SHG is highly dependent on symmetries and provides selective information on the structural order and orientation of the emitting proteins and the dynamics of myosin molecules responsible for the mechano-chemical transduction during contraction. We characterise the polarization-dependence of SHG intensity in three different physiological states: resting, rigor and isometric tetanic contraction in a sarcomere length range between 2.0 μm and 4.0 μm. The orientation of motor domains of the myosin molecules is dependent on their physiological states and modulate the SHG signal. We can discriminate the orientation of the emitting dipoles in four different molecular conformations of myosin heads in intact fibers during isometric contraction, in resting and rigor. We estimate the contribution of the myosin motor domain to the total second order bulk susceptibility from its molecular structure and its functional conformation. We demonstrate that SHG is sensitive to the fraction of ordered myosin heads by disrupting the order of myosin heads in rigor with an ATP analog. We estimate the fraction of myosin motors generating the isometric force in the active muscle fiber from the dependence of the SHG modulation on the degree of overlap between actin and myosin filaments during an isometric contraction.

Structural and molecular interrogation of intact biological systems

PubMed Central

Chung, Kwanghun; Wallace, Jenelle; Kim, Sung-Yon; Kalyanasundaram, Sandhiya; Andalman, Aaron S.; Davidson, Thomas J.; Mirzabekov, Julie J.; Zalocusky, Kelly A.; Mattis, Joanna; Denisin, Aleksandra K.; Pak, Sally; Bernstein, Hannah; Ramakrishnan, Charu; Grosenick, Logan; Gradinaru, Viviana; Deisseroth, Karl

2014-01-01

Obtaining high-resolution information from a complex system, while maintaining the global perspective needed to understand system function, represents a key challenge in biology. Here we address this challenge with a method (termed CLARITY) for the transformation of intact tissue into a nanoporous hydrogel-hybridized form (crosslinked to a three-dimensional network of hydrophilic polymers) that is fully assembled but optically transparent and macromolecule-permeable. Using mouse brains, we show intact-tissue imaging of long-range projections, local circuit wiring, cellular relationships, subcellular structures, protein complexes, nucleic acids and neurotransmitters. CLARITY also enables intact-tissue in situ hybridization, immunohistochemistry with multiple rounds of staining and de-staining in non-sectioned tissue, and antibody labelling throughout the intact adult mouse brain. Finally, we show that CLARITY enables fine structural analysis of clinical samples, including non-sectioned human tissue from a neuropsychiatric-disease setting, establishing a path for the transmutation of human tissue into a stable, intact and accessible form suitable for probing structural and molecular underpinnings of physiological function and disease. PMID:23575631

50 CFR 622.186 - Landing fish intact.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Landing fish intact. 622.186 Section 622...-Grouper Fishery of the South Atlantic Region § 622.186 Landing fish intact. (a) South Atlantic snapper... specified in paragraph (b) of this section. Such fish may be eviscerated, gilled, and scaled, but must...

50 CFR 622.186 - Landing fish intact.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Landing fish intact. 622.186 Section 622...-Grouper Fishery of the South Atlantic Region § 622.186 Landing fish intact. (a) South Atlantic snapper... specified in paragraph (b) of this section. Such fish may be eviscerated, gilled, and scaled, but must...

Motor neuronal activity varies least among individuals when it matters most for behavior

PubMed Central

Cullins, Miranda J.; Shaw, Kendrick M.; Gill, Jeffrey P.

2014-01-01

How does motor neuronal variability affect behavior? To explore this question, we quantified activity of multiple individual identified motor neurons mediating biting and swallowing in intact, behaving Aplysia californica by recording from the protractor muscle and the three nerves containing the majority of motor neurons controlling the feeding musculature. We measured multiple motor components: duration of the activity of identified motor neurons as well as their relative timing. At the same time, we measured behavioral efficacy: amplitude of grasping movement during biting and amplitude of net inward food movement during swallowing. We observed that the total duration of the behaviors varied: Within animals, biting duration shortened from the first to the second and third bites; between animals, biting and swallowing durations varied. To study other sources of variation, motor components were divided by behavior duration (i.e., normalized). Even after normalization, distributions of motor component durations could distinguish animals as unique individuals. However, the degree to which a motor component varied among individuals depended on the role of that motor component in a behavior. Motor neuronal activity that was essential for the expression of biting or swallowing was similar among animals, whereas motor neuronal activity that was not essential for that behavior varied more from individual to individual. These results suggest that motor neuronal activity that matters most for the expression of a particular behavior may vary least from individual to individual. Shaping individual variability to ensure behavioral efficacy may be a general principle for the operation of motor systems. PMID:25411463

Study of adaptation to altered gravity through systems analysis of motor control.

PubMed

Fox, R A; Daunton, N G; Corcoran, M L

1998-01-01

Maintenance of posture and production of functional, coordinated movement demand integration of sensory feedback with spinal and supra-spinal circuitry to produce adaptive motor control in altered gravity (G). To investigate neuroplastic processes leading to optimal performance in altered G we have studied motor control in adult rats using a battery of motor function tests following chronic exposure to various treatments (hyper-G, hindlimb suspension, chemical distruction of hair cells, space flight). These treatments differentially affect muscle fibers, vestibular receptors, and behavioral compensations and, in consequence, differentially disrupt air righting, swimming, posture and gait. The time-course of recovery from these disruptions varies depending on the function tested and the duration and type of treatment. These studies, with others (e.g., D'Amelio et al. in this volume), indicate that adaptation to altered gravity involves alterations in multiple sensory-motor systems that change at different rates. We propose that the use of parallel studies under different altered G conditions will most efficiently lead to an understanding of the modifications in central (neural) and peripheral (sensory and neuromuscular) systems that underlie sensory-motor adaptation in active, intact individuals.

Study of adaptation to altered gravity through systems analysis of motor control

NASA Astrophysics Data System (ADS)

Fox, R. A.; Daunton, N. G.; Corcoran, M. L.

Maintenance of posture and production of functional, coordinated movement demand integration of sensory feedback with spinal and supra-spinal circuitry to produce adaptive motor control in altered gravity (G). To investigate neuroplastic processes leading to optimal performance in altered G we have studied motor control in adult rats using a battery of motor function tests following chronic exposure to various treatments (hyper-G, hindlimb suspension, chemical distruction of hair cells, space flight). These treatments differentially affect muscle fibers, vestibular receptors, and behavioral compensations and, in consequence, differentially disrupt air righting, swimming, posture and gait. The time-course of recovery from these disruptions varies depending on the function tested and the duration and type of treatment. These studies, with others (e.g., D'Amelio et al. in this volume), indicate that adaptation to altered gravity involves alterations in multiple sensory-motor systems that change at different rates. We propose that the use of parallel studies under different altered G conditions will most efficiently lead to an understanding of the modifications in central (neural) and peripheral (sensory and neuromuscular) systems that underlie sensory-motor adaptation in active, intact individuals.

In Helicobacter pylori auto-inducer-2, but not LuxS/MccAB catalysed reverse transsulphuration, regulates motility through modulation of flagellar gene transcription

PubMed Central

2010-01-01

Background LuxS may function as a metabolic enzyme or as the synthase of a quorum sensing signalling molecule, auto-inducer-2 (AI-2); hence, the mechanism underlying phenotypic changes upon luxS inactivation is not always clear. In Helicobacter pylori, we have recently shown that, rather than functioning in recycling methionine as in most bacteria, LuxS (along with newly-characterised MccA and MccB), synthesises cysteine via reverse transsulphuration. In this study, we investigated whether and how LuxS controls motility of H. pylori, specifically if it has its effects via luxS-required cysteine metabolism or via AI-2 synthesis only. Results We report that disruption of luxS renders H. pylori non-motile in soft agar and by microscopy, whereas disruption of mccAHp or mccBHp (other genes in the cysteine provision pathway) does not, implying that the lost phenotype is not due to disrupted cysteine provision. The motility defect of the ΔluxSHp mutant was complemented genetically by luxSHp and also by addition of in vitro synthesised AI-2 or 4, 5-dihydroxy-2, 3-pentanedione (DPD, the precursor of AI-2). In contrast, exogenously added cysteine could not restore motility to the ΔluxSHp mutant, confirming that AI-2 synthesis, but not the metabolic effect of LuxS was important. Microscopy showed reduced number and length of flagella in the ΔluxSHp mutant. Immunoblotting identified decreased levels of FlaA and FlgE but not FlaB in the ΔluxSHp mutant, and RT-PCR showed that the expression of flaA, flgE, motA, motB, flhA and fliI but not flaB was reduced. Addition of DPD but not cysteine to the ΔluxSHp mutant restored flagellar gene transcription, and the number and length of flagella. Conclusions Our data show that as well as being a metabolic enzyme, H. pylori LuxS has an alternative role in regulation of motility by modulating flagellar transcripts and flagellar biosynthesis through production of the signalling molecule AI-2. PMID:20691071

50 CFR 622.38 - Landing fish intact.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Landing fish intact. 622.38 Section 622.38... Landing fish intact. The operator of a vessel that fishes in the EEZ is responsible for ensuring that fish... specified in paragraphs (c) and (d) of this section. Such fish may be eviscerated, gilled, and scaled, but...

Pharmacokinetics of erythropoietin in intact and anephric dogs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, J.S.; Lertora, J.J.; Brookins, J.

1988-06-01

The present studies were performed to determine the pharmacokinetic parameters of erythropoietin in intact and anephric dogs by use of unlabeled crude native erythropoietin (nEp) and iodine 125-labeled purified recombinant erythropoietin (rEp) given by intravenous infusion for 15 minutes. Sephadex G-75 gel filtration was used to confirm that the 125I-rEp molecule remained iodinated in dog plasma during the 24-hour period of these studies. The plasma disappearance of erythropoietin conformed to a biexponential equation for both nEp and 125I-rEp, with the central compartment being larger than the peripheral compartment. The mean distribution half-life of 75.3 +/- 21.2 minutes for nEp wasmore » significantly (p less than 0.05) longer than that of 125I-rEp (23.7 +/- 5.0 minutes) in intact dogs. The intercompartmental clearance (CIic) for nEp (0.018 +/- 0.006 L/kg/hr) was significantly smaller than that of 125I-rEp (0.068 +/- 0.018 L/kg/hr) in intact dogs (p less than 0.05). There were no significant differences in apparent volume of distribution, elimination half-life, and elimination clearance (CIe) for nEp and rEp in intact dogs. The mean elimination half-life for 125I-rEp in intact dogs (9.0 +/- 0.6 hours) and anephric dogs (13.8 +/- 1.4 hours) was significantly different (p less than 0.05). The CIe for 125I-rEp in anephric dogs (0.008 +/- 0.001 L/kg/hr) was significantly (p less than 0.05) smaller than that of 125I-rEp in intact dogs (0.011 +/- 0.001 L/kg/hr). There were no significant differences in apparent volume of distribution, distribution half-life, and CIic for 125I-rEp in intact and anephric dogs.« less

Reduced tonic inhibition after stroke promotes motor performance and epileptic seizures

PubMed Central

Jaenisch, Nadine; Liebmann, Lutz; Guenther, Madlen; Hübner, Christian A.; Frahm, Christiane; Witte, Otto W.

2016-01-01

Stroke survivors often recover from motor deficits, either spontaneously or with the support of rehabilitative training. Since tonic GABAergic inhibition controls network excitability, it may be involved in recovery. Middle cerebral artery occlusion in rodents reduces tonic GABAergic inhibition in the structurally intact motor cortex (M1). Transcript and protein abundance of the extrasynaptic GABAA-receptor complex α4β3δ are concurrently reduced (δ-GABAARs). In vivo and in vitro analyses show that stroke-induced glutamate release activates NMDA receptors, thereby reducing KCC2 transporters and down-regulates δ-GABAARs. Functionally, this is associated with improved motor performance on the RotaRod, a test in which mice are forced to move in a similar manner to rehabilitative training sessions. As an adverse side effect, decreased tonic inhibition facilitates post-stroke epileptic seizures. Our data imply that early and sometimes surprisingly fast recovery following stroke is supported by homeostatic, endogenous plasticity of extrasynaptic GABAA receptors. PMID:27188341

Enhanced Automatic Action Imitation and Intact Imitation-Inhibition in Schizophrenia.

PubMed

Simonsen, Arndis; Fusaroli, Riccardo; Skewes, Joshua Charles; Roepstorff, Andreas; Campbell-Meiklejohn, Daniel; Mors, Ole; Bliksted, Vibeke

2018-02-21

Imitation plays a key role in social learning and in facilitating social interactions and likely constitutes a basic building block of social cognition that supports higher-level social abilities. Recent findings suggest that patients with schizophrenia have imitation impairments that could contribute to the social impairments associated with the disorder. However, extant studies have specifically assessed voluntary imitation or automatic imitation of emotional stimuli without controlling for potential confounders. The imitation impairments seen might therefore be secondary to other cognitive, motoric, or emotional deficits associated with the disorder. To overcome this issue, we used an automatic imitation paradigm with nonemotional stimuli to assess automatic imitation and the top-down modulation of imitation where participants were required to lift one of 2 fingers according to a number shown on the screen while observing the same or the other finger movement. In addition, we used a control task with a visual cue in place of a moving finger, to isolate the effect of observing finger movement from other visual cueing effects. Data from 33 patients (31 medicated) and 40 matched healthy controls were analyzed. Patients displayed enhanced imitation and intact top-down modulation of imitation. The enhanced imitation seen in patients may have been medication induced as larger effects were seen in patients receiving higher antipsychotic doses. In sum, we did not find an imitation impairment in schizophrenia. The results suggest that previous findings of impaired imitation in schizophrenia might have been due to other cognitive, motoric, and/or emotional deficits.

Two Types of Genetic Interaction Implicate the Whirligig Gene of Drosophila Melanogaster in Microtubule Organization in the Flagellar Axoneme

PubMed Central

Green, L. L.; Wolf, N.; McDonald, K. L.; Fuller, M. T.

1990-01-01

The mutant nc4 allele of whirligig (3-54.4) of Drosophila melanogaster fails to complement mutations in an α-tubulin locus, α1t, mutations in a β-tubulin locus, B2t, or a mutation in the haywire locus. However, wrl fails to map to any of the known α- or β-tubulin genes. The extragenic failure to complement could indicate that the wrl product participates in structural interactions with microtubule proteins. The whirligig locus appears to be haploinsufficient for male fertility. Both a deficiency of wrl and possible loss of function alleles obtained by reverting the failure to complement between wrl(nc4) and B2t(n) are dominant male sterile in a genetic background wild type for tubulin. The dominant male sterility of the revertant alleles is suppressed if the flies are also heterozygous for B2t(n), for a deficiency of α1t, or for the hay(nc2) allele. These results suggest that it is not the absolute level of wrl gene product but its level relative to tubulin or microtubule function that is important for normal spermatogenesis. The phenotype of homozygous wrl mutants suggests that the whirligig product plays a role in postmeiotic spermatid differentiation, possibly in organizing the microtubules of the sperm flagellar axoneme. Flies homozygous for either wrl(nc4) or revertant alleles are viable and female fertile but male sterile. Premeiotic and meiotic stages of spermatogenesis appear normal. However, in post-meiotic stages, flagellar axonemes show loss of the accessory microtubule on the B-subfiber of outer doublet microtubules, outer triplet instead of outer doublet microtubules, and missing central pair microtubules. PMID:2127579

Comparison between pre-exercise casein peptide and intact casein supplementation on glucose tolerance in mice fed a high-fat diet.

PubMed

Matsunaga, Yutaka; Tamura, Yuki; Sakata, Yasuyuki; Nonaka, Yudai; Saito, Noriko; Nakamura, Hirohiko; Shimizu, Takashi; Takeda, Yasuhiro; Terada, Shin; Hatta, Hideo

2018-04-01

We hypothesized that along with exercise, casein peptide supplementation would have a higher impact on improving glucose tolerance than intact casein. Male 6-week-old ICR mice were provided a high-fat diet to induce obesity and glucose intolerance. The mice were randomly divided into 4 treatment groups: control (Con), endurance training (Tr), endurance training with intact casein supplementation (Cas+Tr), and endurance training with casein peptide supplementation (CP+Tr). The mice in each group were orally administrated water, intact casein, or casein peptide (1.0 mg/g body weight, every day), and then subjected to endurance training (15-25 m/min, 60 min, 5 times/week for 4 weeks) on a motor-driven treadmill 30 min after ingestion. Our results revealed that total intra-abdominal fat was significantly lower in CP+Tr than in Con (p < 0.05). Following an oral glucose tolerance test, the blood glucose area under the curve (AUC) was found to be significantly smaller for CP+Tr than for Con (p < 0.05). Moreover, in the soleus muscle, glucose transporter 4 (GLUT4) protein levels were significantly higher in CP+Tr than in Con (p < 0.01). However, intra-abdominal fat, blood glucose AUC, and GLUT4 protein content in the soleus muscle did not alter in Tr and Cas+Tr when compared with Con. These observations suggest that pre-exercise casein peptide supplementation has a higher effect on improving glucose tolerance than intact casein does in mice fed a high-fat diet.

Pseudomonas aeruginosa Evasion of Phagocytosis Is Mediated by Loss of Swimming Motility and Is Independent of Flagellum Expression▿ †

PubMed Central

Amiel, Eyal; Lovewell, Rustin R.; O'Toole, George A.; Hogan, Deborah A.; Berwin, Brent

2010-01-01

Pseudomonas aeruginosa is a pathogenic Gram-negative bacterium that causes severe opportunistic infections in immunocompromised individuals; in particular, severity of infection with P. aeruginosa positively correlates with poor prognosis in cystic fibrosis (CF) patients. Establishment of chronic infection by this pathogen is associated with downregulation of flagellar expression and of other genes that regulate P. aeruginosa motility. The current paradigm is that loss of flagellar expression enables immune evasion by the bacteria due to loss of engagement by phagocytic receptors that recognize flagellar components and loss of immune activation through flagellin-mediated Toll-like receptor (TLR) signaling. In this work, we employ bacterial and mammalian genetic approaches to demonstrate that loss of motility, not the loss of the flagellum per se, is the critical factor in the development of resistance to phagocytosis by P. aeruginosa. We demonstrate that isogenic P. aeruginosa mutants deficient in flagellar function, but retaining an intact flagellum, are highly resistant to phagocytosis by both murine and human phagocytic cells at levels comparable to those of flagellum-deficient mutants. Furthermore, we show that loss of MyD88 signaling in murine phagocytes does not recapitulate the phagocytic deficit observed for either flagellum-deficient or motility-deficient P. aeruginosa mutants. Our data demonstrate that loss of bacterial motility confers a dramatic resistance to phagocytosis that is independent of both flagellar expression and TLR signaling. These findings provide an explanation for the well-documented observation of nonmotility in clinical P. aeruginosa isolates and for how this phenotype confers upon the bacteria an advantage in the context of immune evasion. PMID:20457788

Pseudomonas aeruginosa evasion of phagocytosis is mediated by loss of swimming motility and is independent of flagellum expression.

PubMed

Amiel, Eyal; Lovewell, Rustin R; O'Toole, George A; Hogan, Deborah A; Berwin, Brent

2010-07-01

Pseudomonas aeruginosa is a pathogenic Gram-negative bacterium that causes severe opportunistic infections in immunocompromised individuals; in particular, severity of infection with P. aeruginosa positively correlates with poor prognosis in cystic fibrosis (CF) patients. Establishment of chronic infection by this pathogen is associated with downregulation of flagellar expression and of other genes that regulate P. aeruginosa motility. The current paradigm is that loss of flagellar expression enables immune evasion by the bacteria due to loss of engagement by phagocytic receptors that recognize flagellar components and loss of immune activation through flagellin-mediated Toll-like receptor (TLR) signaling. In this work, we employ bacterial and mammalian genetic approaches to demonstrate that loss of motility, not the loss of the flagellum per se, is the critical factor in the development of resistance to phagocytosis by P. aeruginosa. We demonstrate that isogenic P. aeruginosa mutants deficient in flagellar function, but retaining an intact flagellum, are highly resistant to phagocytosis by both murine and human phagocytic cells at levels comparable to those of flagellum-deficient mutants. Furthermore, we show that loss of MyD88 signaling in murine phagocytes does not recapitulate the phagocytic deficit observed for either flagellum-deficient or motility-deficient P. aeruginosa mutants. Our data demonstrate that loss of bacterial motility confers a dramatic resistance to phagocytosis that is independent of both flagellar expression and TLR signaling. These findings provide an explanation for the well-documented observation of nonmotility in clinical P. aeruginosa isolates and for how this phenotype confers upon the bacteria an advantage in the context of immune evasion.

Implicit Perceptual-Motor Skill Learning in Mild Cognitive Impairment and Parkinson's Disease

PubMed Central

Gobel, Eric W.; Blomeke, Kelsey; Zadikoff, Cindy; Simuni, Tanya; Weintraub, Sandy; Reber, Paul J.

2015-01-01

Objective Implicit skill learning is hypothesized to depend on nondeclarative memory that operates independent of the medial temporal lobe (MTL) memory system and instead depends on cortico-striatal circuits between the basal ganglia and cortical areas supporting motor function and planning. Research with the Serial Reaction Time (SRT) task suggests that patients with memory-disorders due to MTL damage exhibit normal implicit sequence learning. However, reports of intact learning rely on observations of no group differences, leading to speculation whether implicit sequence learning is fully intact in these patients. Patients with Parkinson's Disease (PD) often exhibit impaired sequence learning, but this impairment is not universally observed. Method Implicit perceptual-motor sequence learning was examined using the Serial Interception Sequence Learning (SISL) task in patients with amnestic Mild Cognitive Impairment (MCI; n=11) and patients with PD (n=15). Sequence learning in SISL is resistant to explicit learning and individually adapted task difficulty controls for baseline performance differences. Results Patients with MCI exhibited robust sequence learning, equivalent to healthy older adults (n=20), supporting the hypothesis that the MTL does not contribute to learning in this task. In contrast, the majority of patients with PD exhibited no sequence-specific learning in spite of matched overall task performance. Two patients with PD exhibited performance indicative of an explicit compensatory strategy suggesting that impaired implicit learning may lead to greater reliance on explicit memory in some individuals. Conclusion The differences in learning between patient groups provides strong evidence in favor of implicit sequence learning depending solely on intact basal ganglia function with no contribution from the MTL memory system. PMID:23688213

Implicit perceptual-motor skill learning in mild cognitive impairment and Parkinson's disease.

PubMed

Gobel, Eric W; Blomeke, Kelsey; Zadikoff, Cindy; Simuni, Tanya; Weintraub, Sandra; Reber, Paul J

2013-05-01

Implicit skill learning is hypothesized to depend on nondeclarative memory that operates independent of the medial temporal lobe (MTL) memory system and instead depends on cortico striatal circuits between the basal ganglia and cortical areas supporting motor function and planning. Research with the Serial Reaction Time (SRT) task suggests that patients with memory disorders due to MTL damage exhibit normal implicit sequence learning. However, reports of intact learning rely on observations of no group differences, leading to speculation as to whether implicit sequence learning is fully intact in these patients. Patients with Parkinson's disease (PD) often exhibit impaired sequence learning, but this impairment is not universally observed. Implicit perceptual-motor sequence learning was examined using the Serial Interception Sequence Learning (SISL) task in patients with amnestic Mild Cognitive Impairment (MCI; n = 11) and patients with PD (n = 15). Sequence learning in SISL is resistant to explicit learning and individually adapted task difficulty controls for baseline performance differences. Patients with MCI exhibited robust sequence learning, equivalent to healthy older adults (n = 20), supporting the hypothesis that the MTL does not contribute to learning in this task. In contrast, the majority of patients with PD exhibited no sequence-specific learning in spite of matched overall task performance. Two patients with PD exhibited performance indicative of an explicit compensatory strategy suggesting that impaired implicit learning may lead to greater reliance on explicit memory in some individuals. The differences in learning between patient groups provides strong evidence in favor of implicit sequence learning depending solely on intact basal ganglia function with no contribution from the MTL memory system.

An adolescent with intact motor skills and intelligence after infant hemorrhagic stroke without rehabilitation therapy: a case report.

PubMed

Lee, Shenghuo; Yan, Tiebin; Lu, Xiao

2012-01-01

Devastating intracerebral hemorrhagic stroke is rarely encountered in children, but it has a high mortality rate. The case of a 15-year-old boy who survived a major stroke at 40 days old is described. He showed no significant motor or intelligence impairment in adolescence until he was hospitalized for transient left had tremors and slight left hand weakness caused by a cyst. The patient's almost complete motor recovery highlights the power of neural plasticity in young patients. The pediatric stroke was huge, but this did not affect his adolescent movement or intelligence, demonstrating the great neuroplastic potential of the developing human brain. These observations may help increase our knowledge about stroke in children and improve the treatment of pediatric stroke patients.

Antiprotozoal glutathione derivatives with flagellar membrane binding activity against T. brucei rhodesiense.

PubMed

Daunes, Sylvie; Yardley, Vanessa; Croft, Simon L; D'Silva, Claudius

2017-02-15

A new series of N-substituted S-(2,4-dinitrophenyl)glutathione dibutyl diesters were synthesized to improve in vitro anti-protozoal activity against the pathogenic parasites Trypanosoma brucei rhodesiense, Trypanosoma cruzi and Leishmania donovani. The results obtained indicate that N-substituents enhance the inhibitory properties of glutathione diesters whilst showing reduced toxicity against KB cells as in the cases of compounds 5, 9, 10, 16, 18 and 19. We suggest that the interaction of N-substituted S-(2,4-dinitrophenyl) glutathione dibutyl diesters with T. b. brucei occurs mainly by weak hydrophobic interactions such as London and van der Waals forces. A QSAR study indicated that the inhibitory activity of the peptide is associated negatively with the average number of C atoms, N C and positively to S ZX, the ZX shadow a geometric descriptor related to molecular size and orientation of the compound. HPLC-UV studies in conjunction with optical microscopy indicate that the observed selectivity of inhibition of these compounds against bloodstream form T. b. brucei parasites in comparison to L. donovani under the same conditions is due to intracellular uptake via endocytosis in the flagellar pocket. Copyright © 2016. Published by Elsevier Ltd.

Plasticity of Intact Rubral Projections Mediates Spontaneous Recovery of Function after Corticospinal Tract Injury

PubMed Central

Siegel, Chad S.; Fink, Kathren L.; Strittmatter, Stephen M.

2015-01-01

Axons in the adult CNS fail to regenerate after injury, and therefore recovery from spinal cord injury (SCI) is limited. Although full recovery is rare, a modest degree of spontaneous recovery is observed consistently in a broad range of clinical and nonclinical situations. To define the mechanisms mediating spontaneous recovery of function after incomplete SCI, we created bilaterally complete medullary corticospinal tract lesions in adult mice, eliminating a crucial pathway for voluntary skilled movement. Anatomic and pharmacogenetic tools were used to identify the pathways driving spontaneous functional recovery in wild-type and plasticity-sensitized mice lacking Nogo receptor 1. We found that plasticity-sensitized mice recovered 50% of normal skilled locomotor function within 5 weeks of lesion. This significant, yet incomplete, spontaneous recovery was accompanied by extensive sprouting of intact rubrofugal and rubrospinal projections with the emergence of a de novo circuit between the red nucleus and the nucleus raphe magnus. Transient silencing of this rubro–raphe circuit in vivo via activation of the inhibitory DREADD (designer receptor exclusively activated by designer drugs) receptor hM4di abrogated spontaneous functional recovery. These data highlight the pivotal role of uninjured motor circuit plasticity in supporting functional recovery after trauma, and support a focus of experimental strategies on enhancing intact circuit rearrangement to promote functional recovery after SCI. PMID:25632122

46 CFR 178.325 - Intact stability requirements-monohull sailing vessels.

Code of Federal Regulations, 2014 CFR

2014-10-01

... simplified stability proof test detailed in § 178.330 of this part, in the presence of a Coast Guard marine... 46 Shipping 7 2014-10-01 2014-10-01 false Intact stability requirements-monohull sailing vessels... PASSENGER VESSELS (UNDER 100 GROSS TONS) INTACT STABILITY AND SEAWORTHINESS Intact Stability Standards § 178...

46 CFR 178.325 - Intact stability requirements-monohull sailing vessels.

Code of Federal Regulations, 2012 CFR

2012-10-01

... simplified stability proof test detailed in § 178.330 of this part, in the presence of a Coast Guard marine... 46 Shipping 7 2012-10-01 2012-10-01 false Intact stability requirements-monohull sailing vessels... PASSENGER VESSELS (UNDER 100 GROSS TONS) INTACT STABILITY AND SEAWORTHINESS Intact Stability Standards § 178...

46 CFR 178.325 - Intact stability requirements-monohull sailing vessels.

Code of Federal Regulations, 2013 CFR

2013-10-01

... simplified stability proof test detailed in § 178.330 of this part, in the presence of a Coast Guard marine... 46 Shipping 7 2013-10-01 2013-10-01 false Intact stability requirements-monohull sailing vessels... PASSENGER VESSELS (UNDER 100 GROSS TONS) INTACT STABILITY AND SEAWORTHINESS Intact Stability Standards § 178...

Soluble components of the flagellar export apparatus, FliI, FliJ, and FliH, do not deliver flagellin, the major filament protein, from the cytosol to the export gate.

PubMed

Sajó, Ráchel; Liliom, Károly; Muskotál, Adél; Klein, Agnes; Závodszky, Péter; Vonderviszt, Ferenc; Dobó, József

2014-11-01

Flagella, the locomotion organelles of bacteria, extend from the cytoplasm to the cell exterior. External flagellar proteins are synthesized in the cytoplasm and exported by the flagellar type III secretion system. Soluble components of the flagellar export apparatus, FliI, FliH, and FliJ, have been implicated to carry late export substrates in complex with their cognate chaperones from the cytoplasm to the export gate. The importance of the soluble components in the delivery of the three minor late substrates FlgK, FlgL (hook-filament junction) and FliD (filament-cap) has been convincingly demonstrated, but their role in the transport of the major filament component flagellin (FliC) is still unclear. We have used continuous ATPase activity measurements and quartz crystal microbalance (QCM) studies to characterize interactions between the soluble export components and flagellin or the FliC:FliS substrate-chaperone complex. As controls, interactions between soluble export component pairs were characterized providing Kd values. FliC or FliC:FliS did not influence the ATPase activity of FliI alone or in complex with FliH and/or FliJ suggesting lack of interaction in solution. Immobilized FliI, FliH, or FliJ did not interact with FliC or FliC:FliS detected by QCM. The lack of interaction in the fluid phase between FliC or FliC:FliS and the soluble export components, in particular with the ATPase FliI, suggests that cells use different mechanisms for the export of late minor substrates, and the major substrate, FliC. It seems that the abundantly produced flagellin does not require the assistance of the soluble export components to efficiently reach the export gate. Copyright © 2014 Elsevier B.V. All rights reserved.

Neuropsychological function in children with primary complex motor stereotypies.

PubMed

Mahone, E Mark; Ryan, Matthew; Ferenc, Lisa; Morris-Berry, Christina; Singer, Harvey S

2014-10-01

Complex motor stereotypies (CMS) are patterned, repetitive, rhythmic, and involuntary movements that persist over time. They are divided into two subgroups dependent on the presence of other developmental problems: 'primary' (development is otherwise typical) or 'secondary' (associated with autism, intellectual disability, or sensory deficits). There are no currently published studies that examine neuropsychological function in children with primary CMS. This case-control study examines whether children with primary CMS manifest neurobehavioral deficits. Fifty-seven children with primary CMS (32 males, 25 females; mean age 6y 8mo, SD 2y 4mo, range 4-12y) with negative screens for autism and 57 comparison participants (32 males, 25 females; mean age 6y 6mo, SD 2y 1mo) completed neuropsychological assessments of IQ, reading ability, attention, language, and motor and executive functions. Parents completed ratings of their child's repetitive movement severity. The CMS group performed significantly less well than comparison participants on motor skills and IQ tests (both p<0.01), although IQ was consistently in the average range. One-third of the CMS group showed signs of developmental motor coordination difficulties. Parent report of stereotypy severity was significantly associated with parent report of inattention and executive dysfunction. Children with primary CMS were found to have largely intact neuropsychological profiles. Stereotypy severity appears to be associated with executive dysfunction. Although motor difficulties were observed in children with CMS, these were not correlated with parent report of symptom severity. © 2014 Mac Keith Press.

Levodopa response differs in Parkinson's motor subtypes: A task-based effective connectivity study.

PubMed

Mohl, Brianne; Berman, Brian D; Shelton, Erika; Tanabe, Jody

2017-06-15

Parkinson's disease (PD) is a circuit-level disorder with clinically-determined motor subtypes. Despite evidence suggesting each subtype may have different pathophysiology, few neuroimaging studies have examined levodopa-induced differences in neural activation between tremor dominant (TD) and postural instability/gait difficulty (PIGD) subtype patients during a motor task. The goal of this functional MRI (fMRI) study was to examine task-induced activation and connectivity in the cortico-striatal-thalamo-cortical motor circuit in healthy controls, TD patients, and PIGD patients before and after levodopa administration. Fourteen TD and 12 PIGD cognitively-intact patients and 21 age- and sex-matched healthy controls completed a right-hand, paced tapping fMRI paradigm. Collectively, PD patients off medication (OFF) showed hypoactivation of the motor cortex relative to healthy controls, even when controlling for performance. After levodopa intake, the PIGD patients had significantly increased activation in the left putamen compared with TD patients and healthy controls. Psychophysiological interaction analysis revealed that levodopa increased effective connectivity between the posterior putamen and other areas of the motor circuit during tapping in TD patients, but not in PIGD patients. This novel, levodopa-induced difference in the neural responses between PD motor subtypes may have significant implications for elucidating the mechanisms underlying the distinct phenotypic manifestations and enabling the classification of motor subtypes objectively using fMRI. © 2017 Wiley Periodicals, Inc.

50 CFR 622.10 - Landing fish intact--general.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Landing fish intact--general. 622.10... ATLANTIC General Provisions § 622.10 Landing fish intact—-general. This section contains requirements for landing fish intact that are broadly applicable to finfish in the Gulf EEZ and Caribbean EEZ, as specified...

50 CFR 622.10 - Landing fish intact--general.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Landing fish intact--general. 622.10... ATLANTIC General Provisions § 622.10 Landing fish intact—-general. This section contains requirements for landing fish intact that are broadly applicable to finfish in the Gulf EEZ and Caribbean EEZ, as specified...

Reorganization of Motor Cortex by Vagus Nerve Stimulation Requires Cholinergic Innervation.

PubMed

Hulsey, Daniel R; Hays, Seth A; Khodaparast, Navid; Ruiz, Andrea; Das, Priyanka; Rennaker, Robert L; Kilgard, Michael P

2016-01-01

Vagus nerve stimulation (VNS) paired with forelimb training drives robust, specific reorganization of movement representations in the motor cortex. The mechanisms that underlie VNS-dependent enhancement of map plasticity are largely unknown. The cholinergic nucleus basalis (NB) is a critical substrate in cortical plasticity, and several studies suggest that VNS activates cholinergic circuitry. We examined whether the NB is required for VNS-dependent enhancement of map plasticity in the motor cortex. Rats were trained to perform a lever pressing task and then received injections of the immunotoxin 192-IgG-saporin to selectively lesion cholinergic neurons of the NB. After lesion, rats underwent five days of motor training during which VNS was paired with successful trials. At the conclusion of behavioral training, intracortical microstimulation was used to document movement representations in motor cortex. VNS paired with forelimb training resulted in a substantial increase in the representation of proximal forelimb in rats with an intact NB compared to untrained controls. NB lesions prevent this VNS-dependent increase in proximal forelimb area and result in representations similar to untrained controls. Motor performance was similar between groups, suggesting that differences in forelimb function cannot account for the difference in proximal forelimb representation. Together, these findings indicate that the NB is required for VNS-dependent enhancement of plasticity in the motor cortex and may provide insight into the mechanisms that underlie the benefits of VNS therapy. Copyright © 2016 Elsevier Inc. All rights reserved.

Sensorimotor nucleus NIf is necessary for auditory processing but not vocal motor output in the avian song system.

PubMed

Cardin, Jessica A; Raksin, Jonathan N; Schmidt, Marc F

2005-04-01

Sensorimotor integration in the avian song system is crucial for both learning and maintenance of song, a vocal motor behavior. Although a number of song system areas demonstrate both sensory and motor characteristics, their exact roles in auditory and premotor processing are unclear. In particular, it is unknown whether input from the forebrain nucleus interface of the nidopallium (NIf), which exhibits both sensory and premotor activity, is necessary for both auditory and premotor processing in its target, HVC. Here we show that bilateral NIf lesions result in long-term loss of HVC auditory activity but do not impair song production. NIf is thus a major source of auditory input to HVC, but an intact NIf is not necessary for motor output in adult zebra finches.

Morphological differences in skeletal muscle atrophy of rats with motor nerve and/or sensory nerve injury★

PubMed Central

Zhao, Lei; Lv, Guangming; Jiang, Shengyang; Yan, Zhiqiang; Sun, Junming; Wang, Ling; Jiang, Donglin

2012-01-01

Skeletal muscle atrophy occurs after denervation. The present study dissected the rat left ventral root and dorsal root at L4-6 or the sciatic nerve to establish a model of simple motor nerve injury, sensory nerve injury or mixed nerve injury. Results showed that with prolonged denervation time, rats with simple motor nerve injury, sensory nerve injury or mixed nerve injury exhibited abnormal behavior, reduced wet weight of the left gastrocnemius muscle, decreased diameter and cross-sectional area and altered ultrastructure of muscle cells, as well as decreased cross-sectional area and increased gray scale of the gastrocnemius muscle motor end plate. Moreover, at the same time point, the pathological changes were most severe in mixed nerve injury, followed by simple motor nerve injury, and the changes in simple sensory nerve injury were the mildest. These findings indicate that normal skeletal muscle morphology is maintained by intact innervation. Motor nerve injury resulted in larger damage to skeletal muscle and more severe atrophy than sensory nerve injury. Thus, reconstruction of motor nerves should be considered first in the clinical treatment of skeletal muscle atrophy caused by denervation. PMID:25337102

The Mr 140,000 Intermediate Chain of Chlamydomonas Flagellar Inner Arm Dynein Is a WD-Repeat Protein Implicated in Dynein Arm Anchoring

PubMed Central

Yang, Pinfen; Sale, Winfield S.

1998-01-01

Previous structural and biochemical studies have revealed that the inner arm dynein I1 is targeted and anchored to a unique site located proximal to the first radial spoke in each 96-nm axoneme repeat on flagellar doublet microtubules. To determine whether intermediate chains mediate the positioning and docking of dynein complexes, we cloned and characterized the 140-kDa intermediate chain (IC140) of the I1 complex. Sequence and secondary structural analysis, with particular emphasis on β-sheet organization, predicted that IC140 contains seven WD repeats. Reexamination of other members of the dynein intermediate chain family of WD proteins indicated that these polypeptides also bear seven WD/β-sheet repeats arranged in the same pattern along each intermediate chain protein. A polyclonal antibody was raised against a 53-kDa fusion protein derived from the C-terminal third of IC140. The antibody is highly specific for IC140 and does not bind to other dynein intermediate chains or proteins in Chlamydomonas flagella. Immunofluorescent microscopy of Chlamydomonas cells confirmed that IC140 is distributed along the length of both flagellar axonemes. In vitro reconstitution experiments demonstrated that the 53-kDa C-terminal fusion protein binds specifically to axonemes lacking the I1 complex. Chemical cross-linking indicated that IC140 is closely associated with a second intermediate chain in the I1 complex. These data suggest that IC140 contains domains responsible for the assembly and docking of the I1 complex to the doublet microtubule cargo. PMID:9843573

Autism Spectrum Disorder and intact executive functioning.

PubMed

Ferrara, R; Ansermet, F; Massoni, F; Petrone, L; Onofri, E; Ricci, P; Archer, T; Ricci, S

2016-01-01

Earliest notions concerning autism (Autism Spectrum Disorders, ASD) describe the disturbance in executive functioning. Despite altered definition, executive functioning, expressed as higher cognitive skills required complex behaviors linked to the prefrontal cortex, are defective in autism. Specific difficulties in children presenting autism or verbal disabilities at executive functioning levels have been identified. Nevertheless, the developmental deficit of executive functioning in autism is highly diversified with huge individual variation and may even be absent. The aim of the present study to examine the current standing of intact executive functioning intact in ASD. Analysis of ASD populations, whether high-functioning, Asperger's or autism Broad Phenotype, studied over a range of executive functions including response inhibition, planning, cognitive flexibility, cognitive inhibition, and alerting networks indicates an absence of damage/impairment compared to the typically-developed normal control subjects. These findings of intact executive functioning in ASD subjects provide a strong foundation on which to construct applications for growth environments and the rehabilitation of autistic subjects.

Coupling biochemistry and hydrodynamics captures hyperactivated sperm motility in a simple flagellar model

PubMed Central

Olson, Sarah D.; Suarez, Susan S.; Fauci, Lisa J.

2011-01-01

Hyperactivation in mammalian sperm is characterized by highly asymmetrical waveforms and an increase in the amplitude of flagellar bends. It is important for the sperm to be able to achieve hyperactivated motility in order to reach and fertilize the egg. Calcium (Ca2+) dynamics are known to play a large role in the initiation and maintenance of hyperactivated motility. Here we present an integrative model that couples the CatSper channel mediated Ca2+ dynamics of hyperactivation to a mechanical model of an idealized sperm flagellum in a 3-d viscous, incompressible fluid. The mechanical forces are due to passive stiffness properties and active bending moments that are a function of the local Ca2+ concentration along the length of the flagellum. By including an asymmetry in bending moments to reflect an asymmetry in the axoneme’s response to Ca2+, we capture the transition from activated motility to hyperactivated motility. We examine the effects of elastic properties of the flagellum and the Ca2+ dynamics on the overall swimming patterns. The swimming velocities of the model flagellum compare well with data for hyperactivated mouse sperm. PMID:21669209

Protein Synthesis Inhibition in the Peri-Infarct Cortex Slows Motor Recovery in Rats.

PubMed

Schubring-Giese, Maximilian; Leemburg, Susan; Luft, Andreas Rüdiger; Hosp, Jonas Aurel

2016-01-01

Neuroplasticity and reorganization of brain motor networks are thought to enable recovery of motor function after ischemic stroke. Especially in the cortex surrounding the ischemic scar (i.e., peri-infarct cortex), evidence for lasting reorganization has been found at the level of neurons and networks. This reorganization depends on expression of specific genes and subsequent protein synthesis. To test the functional relevance of the peri-infarct cortex for recovery we assessed the effect of protein synthesis inhibition within this region after experimental stroke. Long-Evans rats were trained to perform a skilled-reaching task (SRT) until they reached plateau performance. A photothrombotic stroke was induced in the forelimb representation of the primary motor cortex (M1) contralateral to the trained paw. The SRT was re-trained after stroke while the protein synthesis inhibitor anisomycin (ANI) or saline were injected into the peri-infarct cortex through implanted cannulas. ANI injections reduced protein synthesis within the peri-infarct cortex by 69% and significantly impaired recovery of reaching performance through re-training. Improvement of motor performance within a single training session remained intact, while improvement between training sessions was impaired. ANI injections did not affect infarct size. Thus, protein synthesis inhibition within the peri-infarct cortex impairs recovery of motor deficits after ischemic stroke by interfering with consolidation of motor memory between training sessions but not short-term improvements within one session.

Interactive Effects of Dorsomedial Hypothalamic Nucleus and Time-Restricted Feeding on Fractal Motor Activity Regulation.

PubMed

Lo, Men-Tzung; Chiang, Wei-Yin; Hsieh, Wan-Hsin; Escobar, Carolina; Buijs, Ruud M; Hu, Kun

2016-01-01

One evolutionary adaptation in motor activity control of animals is the anticipation of food that drives foraging under natural conditions and is mimicked in laboratory with daily scheduled food availability. Food anticipation is characterized by increased activity a few hours before the feeding period. Here we report that 2-h food availability during the normal inactive phase of rats not only increases activity levels before the feeding period but also alters the temporal organization of motor activity fluctuations over a wide range of time scales from minutes up to 24 h. We demonstrate this multiscale alteration by assessing fractal patterns in motor activity fluctuations-similar fluctuation structure at different time scales-that are robust in intact animals with ad libitum food access but are disrupted under food restriction. In addition, we show that fractal activity patterns in rats with ad libitum food access are also perturbed by lesion of the dorsomedial hypothalamic (DMH)-a neural node that is involved in food anticipatory behavior. Instead of further disrupting fractal regulation, food restriction restores the disrupted fractal patterns in these animals after the DMH lesion despite the persistence of the 24-h rhythms. This compensatory effect of food restriction is more clearly pronounced in the same animals after the additional lesion of the suprachiasmatic nucleus (SCN)-the central master clock in the circadian system that generates and orchestrates circadian rhythms in behavior and physiological functions in synchrony with day-night cycles. Moreover, all observed influences of food restriction persist even when data during the food anticipatory and feeding period are excluded. These results indicate that food restriction impacts dynamics of motor activity at different time scales across the entire circadian/daily cycle, which is likely caused by the competition between the food-induced time cue and the light-entrained circadian rhythm of the SCN. The

Mapping Flagellar Genes in Chlamydomonas Using Restriction Fragment Length Polymorphisms

PubMed Central

Ranum, LPW.; Thompson, M. D.; Schloss, J. A.; Lefebvre, P. A.; Silflow, C. D.

1988-01-01

To correlate cloned nuclear DNA sequences with previously characterized mutations in Chlamydomonas and, to gain insight into the organization of its nuclear genome, we have begun to map molecular markers using restriction fragment length polymorphisms (RFLPs). A Chlamydomonas reinhardtii strain (CC-29) containing phenotypic markers on nine of the 19 linkage groups was crossed to the interfertile species Chlamydomonas smithii. DNA from each member of 22 randomly selected tetrads was analyzed for the segregation of RFLPs associated with cloned genes detected by hybridization with radioactive DNA probes. The current set of markers allows the detection of linkage to new molecular markers over approximately 54% of the existing genetic map. This study focused on mapping cloned flagellar genes and genes whose transcripts accumulate after deflagellation. Twelve different molecular clones have been assigned to seven linkage groups. The α-1 tubulin gene maps to linkage group III and is linked to the genomic sequence homologous to pcf6-100, a cDNA clone whose corresponding transcript accumulates after deflagellation. The α-2 tubulin gene maps to linkage group IV. The two β-tubulin genes are linked, with the β-1 gene being approximately 12 cM more distal from the centromere than the β-2 gene. A clone corresponding to a 73-kD dynein protein maps to the opposite arm of the same linkage group. The gene corresponding to the cDNA clone pcf6-187, whose mRNA accumulates after deflagellation, maps very close to the tightly linked pf-26 and pf-1 mutations on linkage group V. PMID:2906025

Avoiding Complications in Abdominal Wall Surgery: A Mathematical Model to Predict the Course of the Motor Innervation of the Rectus Abdominis.

PubMed

Tessone, Ariel; Nava, Maurizio; Blondeel, Phillip; Spano, Andrea

2016-02-01

Ever since its introduction, the transverse rectus abdominis myocutaneous flap has become the mainstay of autologous breast reconstruction. However, concerns regarding donor site morbidity due to the breach of abdominal wall musculature integrity soon followed. Muscle-sparing techniques, eventually eliminating the muscle from the flap all-together with the deep inferior epigastric artery perforator flap, did not eliminate the problem of abdominal wall weakness. This led to the conclusion that motor innervation might be at fault. Studies have shown that even in the presence of an intact rectus abdominis muscle, and an intact anterior rectus sheath, denervation of the rectus abdominis muscle results in significant abdominal wall weakness leading to superior and inferior abdominal bulges, and abdominal herniation. Our aim was to establish a mathematical model to predict the location of the motor innervation to the rectus abdominis muscle, and thus provide surgeons with a tool that will allow them to reduce abdominal morbidity during deep inferior epigastric artery perforator and free muscle-sparing transverse rectus abdominis myocutaneous surgery. We dissected 42 cadaveric hemiabdomens and mapped the course of the thoracolumbar nerves. We then standardized and analyzed our findings and presented them as a relative map which can be adjusted to body type and dimensions. Our dissections show that the motor innervation is closely related to the lateral vascular supply. Thus, when possible, we support the preferred utilization of the medial vascular supply, and the preservation of the lateral supply and motor innervation.

Flagellar coordination in Chlamydomonas cells held on micropipettes.

PubMed

Rüffer, U; Nultsch, W

1998-01-01

The two flagella of Chlamydomonas are known to beat synchronously: During breaststroke beating they are generally coordinated in a bilateral way while in shock responses during undulatory beating coordination is mostly parallel [Rüffer and Nultsch, 1995: Botanica Acta 108:169-276]. Analysis of a great number of shock responses revealed that in undulatory beats also periods of bilateral coordination are found and that the coordination type may change several times during a shock response, without concomitant changes of the beat envelope and the beat period. In normal wt cells no coordination changes are found during breaststroke beating, but only short temporary asynchronies: During 2 or 3 normal beats of the cis flagellum, the trans flagellum performs 3 or 4 flat beats with a reduced beat envelope and a smaller beat period, resulting in one additional trans beat. Long periods with flat beats of the same shape and beat period are found in both flagella of the non-phototactic mutant ptx1 and in defective wt 622E cells. During these periods, the coordination is parallel, the two flagella beat alternately. A correlation between normal asynchronous trans beats and the parallel-coordinated beats in the presumably cis defective cells and also the undulatory beats is discussed. In the cis defective cells, a perpetual spontaneous change between parallel beats with small beat periods (higher beat frequency) and bilateral beats with greater beat periods (lower beat frequency) are observed and render questionable the existence of two different intrinsic beat frequencies of the two flagella cis and trans. Asynchronies occur spontaneously but may also be induced by light changes, either step-up or step-down, but not by both stimuli in turn as breaststroke flagellar photoresponses (BFPRs). Asynchronies are not involved in phototaxis. They are independent of the BFPRs, which are supposed to be the basis of phototaxis. Both types of coordination must be assumed to be regulated

Robotic set-up to quantify hand-eye behavior in motor execution and learning of children with autism spectrum disorder.

PubMed

Casellato, Claudia; Gandolla, Marta; Crippa, Alessandro; Pedrocchi, Alessandra

2017-07-01

Autism spectrum disorder (ASD) is a multifaceted neurodevelopmental disorder characterized by a persistence of social and communication impairment, and restricted and repetitive behaviors. However, motor disorders have also been described, but not objectively assessed. Most studies showed inefficient eye-hand coordination and motor learning in children with ASD; in other experiments, mechanisms of acquisition of internal models in self-generated movements appeared to be normal in autism. In this framework, we have developed a robotic protocol, recording gaze and hand data during upper limb tasks, in which a haptic pen-like handle is moved along specific trajectories displayed on the screen. The protocol includes trials of reaching under a perturbing force field and catching moving targets, with or without visual availability of the whole path. We acquired 16 typically-developing scholar-age children and one child with ASD as a case study. Speed-accuracy tradeoff, motor performance, and gaze-hand spatial coordination have been evaluated. Compared to typically developing peers, in the force field sequence, the child with ASD showed an intact but delayed learning, and more variable gazehand patterns. In the catching trials, he showed less efficient movements, but an intact capability of exploiting the available a-priori plan. The proposed protocol represents a powerful tool, easily tunable, for quantitative (longitudinal) assessment, and for subject-tailored training in ASD.

Voluntary exercise impact on cognitive impairments in sleep-deprived intact female rats.

PubMed

Rajizadeh, Mohammad Amin; Esmaeilpour, Khadijeh; Masoumi-Ardakani, Yaser; Bejeshk, Mohammad Abbas; Shabani, Mohammad; Nakhaee, Nouzar; Ranjbar, Mohammad Pour; Borzadaran, Fatemeh Mohtashami; Sheibani, Vahid

2018-05-01

Sleep loss is a common problem in modern societies affecting different aspects of individuals' lives. Many studies have reported that sleep deprivation (SD) leads to impairments in various types of learning and memory. Physical exercise has been suggested to attenuate the cognitive impairments induced by sleep deprivation in male rats. Our previous studies have shown that forced exercise by treadmill improved learning and memory impairments following SD. The aim of the current study was to investigate the effects of voluntary exercise by running wheel on cognitive, motor and anxiety-like behavior functions of female rats following 72 h SD. Intact female rats were used in the present study. The multiple platform method was applied for the induction of 72 h SD. The exercise protocol was 4 weeks of running wheel and the cognitive function was evaluated using Morris water maze (MWM), passive avoidance and novel object recognition tests. Open field test and measurement of plasma corticosterone level were performed for evaluation of anxiety-like behaviors. Motor balance evaluation was surveyed by rotarod test. In this study, remarkable learning and long-term memory impairments were observed in sleep deprived rats in comparison to the other groups. Running wheel exercise ameliorated the SD-induced learning and memory impairments. Voluntary and mandatory locomotion and balance situation were not statistically significant among the different groups. Our study confirmed the negative effects of SD on cognitive function and approved protective effects of voluntary exercise on these negative effects. Copyright © 2018 Elsevier Inc. All rights reserved.

Interplay between the Localization and Kinetics of Phosphorylation in Flagellar Pole Development of the Bacterium Caulobacter crescentus

PubMed Central

Tropini, Carolina; Huang, Kerwyn Casey

2012-01-01

Bacterial cells maintain sophisticated levels of intracellular organization that allow for signal amplification, response to stimuli, cell division, and many other critical processes. The mechanisms underlying localization and their contribution to fitness have been difficult to uncover, due to the often challenging task of creating mutants with systematically perturbed localization but normal enzymatic activity, and the lack of quantitative models through which to interpret subtle phenotypic changes. Focusing on the model bacterium Caulobacter crescentus, which generates two different types of daughter cells from an underlying asymmetric distribution of protein phosphorylation, we use mathematical modeling to investigate the contribution of the localization of histidine kinases to the establishment of cellular asymmetry and subsequent developmental outcomes. We use existing mutant phenotypes and fluorescence data to parameterize a reaction-diffusion model of the kinases PleC and DivJ and their cognate response regulator DivK. We then present a systematic computational analysis of the effects of changes in protein localization and abundance to determine whether PleC localization is required for correct developmental timing in Caulobacter. Our model predicts the developmental phenotypes of several localization mutants, and suggests that a novel strain with co-localization of PleC and DivJ could provide quantitative insight into the signaling threshold required for flagellar pole development. Our analysis indicates that normal development can be maintained through a wide range of localization phenotypes, and that developmental defects due to changes in PleC localization can be rescued by increased PleC expression. We also show that the system is remarkably robust to perturbation of the kinetic parameters, and while the localization of either PleC or DivJ is required for asymmetric development, the delocalization of one of these two components does not prevent

Noxious lingual stimulation influences the excitability of the face primary motor cerebral cortex (face MI) in the rat.

PubMed

Adachi, K; Murray, G M; Lee, J-C; Sessle, B J

2008-09-01

The mechanisms whereby orofacial pain affects motor function are poorly understood. The aims were to determine whether 1) lingual algesic chemical stimulation affected face primary motor cerebral cortex (face MI) excitability defined by intracortical microstimulation (ICMS); and 2) any such effects were limited to the motor efferent MI zones driving muscles in the vicinity of the noxious stimulus. Ketamine-anesthetized Sprague-Dawley male rats were implanted with electromyographic (EMG) electrodes into anterior digastric, masseter, and genioglossus muscles. In 38 rats, three microelectrodes were located in left face MI at ICMS-defined sites for evoking digastric and/or genioglossus responses. ICMS thresholds for evoking EMG activity from each site were determined every 15 min for 1 h, then the right anterior tongue was infused (20 microl, 120 microl/h) with glutamate (1.0 M, n = 18) or isotonic saline (n = 7). Subsequently, ICMS thresholds were determined every 15 min for 4 h. In intact control rats (n = 13), ICMS thresholds were recorded over 5 h. Only left and right genioglossus ICMS thresholds were significantly increased (< or =350%) in the glutamate infusion group compared with intact and isotonic saline groups (P < 0.05). These dramatic effects of glutamate on ICMS-evoked genioglossus activity contrast with its weak effects only on right genioglossus activity evoked from the internal capsule or hypoglossal nucleus. This is the first documentation that intraoral noxious stimulation results in prolonged neuroplastic changes manifested as a decrease in face MI excitability. These changes appear to occur predominantly in those parts of face MI that provide motor output to the orofacial region receiving the noxious stimulation.

Lipopolysaccharide-Specific but Not Anti-Flagellar Immunoglobulin A Monoclonal Antibodies Prevent Salmonella enterica Serotype Enteritidis Invasion and Replication within HEp-2 Cell Monolayers

PubMed Central

Iankov, Ianko D.; Petrov, Dragomir P.; Mladenov, Ivan V.; Haralambieva, Iana H.; Mitov, Ivan G.

2002-01-01

The protective potential of immunoglobulin A (IgA) monoclonal antibodies (MAbs) directed against O and H antigens of Salmonella enterica serotype Enteritidis to prevent bacterial adhesion to and invasion of HEp-2 cells was evaluated. Although anti-flagellar IgA MAbs showed strong agglutinating capacities, they did not protect cell monolayers. In contrast, IgA MAbs specific for the O:9 epitope of Salmonella lipopolysaccharide antigen alone prevented S. enterica serotype Enteritidis entry and replication within HEp-2 cells, and the protection was not mediated by direct binding of antibodies to bacterial adhesins or by agglutination of microorganisms. PMID:11854252

Two new species of Piaroa (Arachnida: Schizomida, Hubbardiidae) from Colombia, with comments on the genus taxonomy and the flagellar setae pattern of Hubbardiinae.

PubMed

Moreno-González, Jairo A; Delgado-Santa, Leonardo; De Armas, Luis F

2014-08-14

Two new species of the genus Piaroa Villarreal, Tourinho & Giupponi, 2008, P. escalerete sp. nov. and P. bacata sp. nov. are described from Valle del Cauca, and Cundinamarca departments, Colombia, respectively. The female flagellum is fully illustrated for a Piaroa species for the first time; the generic diagnosis is also emended and the relationships of the new species with those previously described are discussed. New characters for Piaroa species, a new nomenclature for the chitinized arch and a reinterpretation of the Hubbardiinae flagellar setae pattern are proposed. A distribution map of the known species of Piaroa is provided. 

Crystallization of FcpA from Leptospira, a novel flagellar protein that is essential for pathogenesis.

PubMed

San Martin, Fabiana; Mechaly, Ariel E; Larrieux, Nicole; Wunder, Elsio A; Ko, Albert I; Picardeau, Mathieu; Trajtenberg, Felipe; Buschiazzo, Alejandro

2017-03-01

The protein FcpA is a unique component of the flagellar filament of spirochete bacteria belonging to the genus Leptospira. Although it plays an essential role in translational motility and pathogenicity, no structures of FcpA homologues are currently available in the PDB. Its three-dimensional structure will unveil the novel motility mechanisms that render pathogenic Leptospira particularly efficient at invading and disseminating within their hosts, causing leptospirosis in humans and animals. FcpA from L. interrogans was purified and crystallized, but despite laborious attempts no useful X ray diffraction data could be obtained. This challenge was solved by expressing a close orthologue from the related saprophytic species L. biflexa. Three different crystal forms were obtained: a primitive and a centred monoclinic form, as well as a hexagonal variant. All forms diffracted X-rays to suitable resolutions for crystallographic analyses, with the hexagonal type typically reaching the highest limits of 2.0 Å and better. A variation of the quick-soaking procedure resulted in an iodide derivative that was instrumental for single-wavelength anomalous diffraction methods.

Cognitive-motor interactions of the basal ganglia in development

PubMed Central

Leisman, Gerry; Braun-Benjamin, Orit; Melillo, Robert

2014-01-01

Neural circuits linking activity in anatomically segregated populations of neurons in subcortical structures and the neocortex throughout the human brain regulate complex behaviors such as walking, talking, language comprehension, and other cognitive functions associated with frontal lobes. The basal ganglia, which regulate motor control, are also crucial elements in the circuits that confer human reasoning and adaptive function. The basal ganglia are key elements in the control of reward-based learning, sequencing, discrete elements that constitute a complete motor act, and cognitive function. Imaging studies of intact human subjects and electrophysiologic and tracer studies of the brains and behavior of other species confirm these findings. We know that the relation between the basal ganglia and the cerebral cortical region allows for connections organized into discrete circuits. Rather than serving as a means for widespread cortical areas to gain access to the motor system, these loops reciprocally interconnect a large and diverse set of cerebral cortical areas with the basal ganglia. Neuronal activity within the basal ganglia associated with motor areas of the cerebral cortex is highly correlated with parameters of movement. Neuronal activity within the basal ganglia and cerebellar loops associated with the prefrontal cortex is related to the aspects of cognitive function. Thus, individual loops appear to be involved in distinct behavioral functions. Damage to the basal ganglia of circuits with motor areas of the cortex leads to motor symptoms, whereas damage to the subcortical components of circuits with non-motor areas of the cortex causes higher-order deficits. In this report, we review some of the anatomic, physiologic, and behavioral findings that have contributed to a reappraisal of function concerning the basal ganglia and cerebellar loops with the cerebral cortex and apply it in clinical applications to attention deficit/hyperactivity disorder (ADHD

Influence of respiratory motor neurone activity on human autonomic and haemodynamic rhythms

NASA Technical Reports Server (NTRS)

Gonschorek, A. S.; Lu, L. L.; Halliwill, J. R.; Beightol, L. A.; Taylor, J. A.; Painter, J. A.; Warzel, H.; Eckberg, D. L.

2001-01-01

Although humans hold great advantages over other species as subjects for biomedical research, they also bring major disadvantages. One is that among the many rhythmic physiological signals that can be recorded, there is no sure way to know which individual change precedes another, or which change represents cause and which represents effect. In an attempt to deal with the inherent complexity of research conducted in intact human subjects, we developed and used a structural equation model to analyse responses of healthy young men to pharmacological changes of arterial pressure and graded inspiratory resistance, before and after vagomimetic atropine. Our model yielded a good fit of the experimental data, with a system weighted R2 of 0.77, and suggested that our treatments exerted both direct and indirect influences on the variables we measured. Thus, infusions of nitroprusside and phenylephrine exerted all of their direct effects by lowering and raising arterial pressure; the changes of R-R intervals, respiratory sinus arrhythmia and arterial pressure fluctuations that these drugs provoked, were indirect consequences of arterial pressure changes. The only direct effect of increased inspiratory resistance was augmentation of arterial pressure fluctuations. These results may provide a new way to disentangle and understand responses of intact human subjects to experimental forcings. The principal new insight we derived from our modelling is that respiratory gating of vagal-cardiac motor neurone firing is nearly maximal at usual levels of arterial pressure and inspiratory motor neurone activity.

Imaging of the 3D dynamics of flagellar beating in human sperm.

PubMed

Silva-Villalobos, F; Pimentel, J A; Darszon, A; Corkidi, G

2014-01-01

The study of the mechanical and environmental factors that regulate a fundamental event such as fertilization have been subject of multiple studies. Nevertheless, the microscopical size of the spermatozoa and the high beating frequency of their flagella (up to 20 Hz) impose a series of technological challenges for the study of the mechanical factors implicated. Traditionally, due to the inherent characteristics of the rapid sperm movement, and to the technological limitations of microscopes (optical or confocal) to follow in three dimensions (3D) their movement, the analysis of their dynamics has been studied in two dimensions, when the head is confined to a surface. Flagella propel sperm and while their head can be confined to a surface, flagellar movement is not restricted to 2D, always displaying 3D components. In this work, we present a highly novel and useful tool to analyze sperm flagella dynamics in 3D. The basis of the method is a 100 Hz oscillating objective mounted on a bright field optical microscope covering a 16 microns depth space at a rate of ~ 5000 images per second. The best flagellum focused subregions were associated to their respective Z real 3D position. Unprecedented graphical results making evident the 3D movement of the flagella are shown in this work and supplemental material illustrating a 3D animation using the obtained experimental results is also included.

pH regulates genes for flagellar motility, catabolism, and oxidative stress in Escherichia coli K-12.

PubMed

Maurer, Lisa M; Yohannes, Elizabeth; Bondurant, Sandra S; Radmacher, Michael; Slonczewski, Joan L

2005-01-01

Gene expression profiles of Escherichia coli K-12 W3110 were compared as a function of steady-state external pH. Cultures were grown to an optical density at 600 nm of 0.3 in potassium-modified Luria-Bertani medium buffered at pH 5.0, 7.0, and 8.7. For each of the three pH conditions, cDNA from RNA of five independent cultures was hybridized to Affymetrix E. coli arrays. Analysis of variance with an alpha level of 0.001 resulted in 98% power to detect genes showing a twofold difference in expression. Normalized expression indices were calculated for each gene and intergenic region (IG). Differential expression among the three pH classes was observed for 763 genes and 353 IGs. Hierarchical clustering yielded six well-defined clusters of pH profiles, designated Acid High (highest expression at pH 5.0), Acid Low (lowest expression at pH 5.0), Base High (highest at pH 8.7), Base Low (lowest at pH 8.7), Neutral High (highest at pH 7.0, lower in acid or base), and Neutral Low (lowest at pH 7.0, higher at both pH extremes). Flagellar and chemotaxis genes were repressed at pH 8.7 (Base Low cluster), where the cell's transmembrane proton potential is diminished by the maintenance of an inverted pH gradient. High pH also repressed the proton pumps cytochrome o (cyo) and NADH dehydrogenases I and II. By contrast, the proton-importing ATP synthase F1Fo and the microaerophilic cytochrome d (cyd), which minimizes proton export, were induced at pH 8.7. These observations are consistent with a model in which high pH represses synthesis of flagella, which expend proton motive force, while stepping up electron transport and ATPase components that keep protons inside the cell. Acid-induced genes, on the other hand, were coinduced by conditions associated with increased metabolic rate, such as oxidative stress. All six pH-dependent clusters included envelope and periplasmic proteins, which directly experience external pH. Overall, this study showed that (i) low pH accelerates acid

Using ipsilateral motor signals in the unaffected cerebral hemisphere as a signal platform for brain-computer interfaces in hemiplegic stroke survivors

NASA Astrophysics Data System (ADS)

Bundy, David T.; Wronkiewicz, Mark; Sharma, Mohit; Moran, Daniel W.; Corbetta, Maurizio; Leuthardt, Eric C.

2012-06-01

Brain-computer interface (BCI) systems have emerged as a method to restore function and enhance communication in motor impaired patients. To date, this has been applied primarily to patients who have a compromised motor outflow due to spinal cord dysfunction, but an intact and functioning cerebral cortex. The cortical physiology associated with movement of the contralateral limb has typically been the signal substrate that has been used as a control signal. While this is an ideal control platform in patients with an intact motor cortex, these signals are lost after a hemispheric stroke. Thus, a different control signal is needed that could provide control capability for a patient with a hemiparetic limb. Previous studies have shown that there is a distinct cortical physiology associated with ipsilateral, or same-sided, limb movements. Thus far, it was unknown whether stroke survivors could intentionally and effectively modulate this ipsilateral motor activity from their unaffected hemisphere. Therefore, this study seeks to evaluate whether stroke survivors could effectively utilize ipsilateral motor activity from their unaffected hemisphere to achieve this BCI control. To investigate this possibility, electroencephalographic (EEG) signals were recorded from four chronic hemispheric stroke patients as they performed (or attempted to perform) real and imagined hand tasks using either their affected or unaffected hand. Following performance of the screening task, the ability of patients to utilize a BCI system was investigated during on-line control of a one-dimensional control task. Significant ipsilateral motor signals (associated with movement intentions of the affected hand) in the unaffected hemisphere, which were found to be distinct from rest and contralateral signals, were identified and subsequently used for a simple online BCI control task. We demonstrate here for the first time that EEG signals from the unaffected hemisphere, associated with overt and

Electrical stimulation of transplanted motoneurons improves motor unit formation

PubMed Central

Liu, Yang; Grumbles, Robert M.

2014-01-01

Motoneurons die following spinal cord trauma and with neurological disease. Intact axons reinnervate nearby muscle fibers to compensate for the death of motoneurons, but when an entire motoneuron pool dies, there is complete denervation. To reduce denervation atrophy, we have reinnervated muscles in Fisher rats from local transplants of embryonic motoneurons in peripheral nerve. Since growth of axons from embryonic neurons is activity dependent, our aim was to test whether brief electrical stimulation of the neurons immediately after transplantation altered motor unit numbers and muscle properties 10 wk later. All surgical procedures and recordings were done in anesthetized animals. The muscle consequences of motoneuron death were mimicked by unilateral sciatic nerve section. One week later, 200,000 embryonic day 14 and 15 ventral spinal cord cells, purified for motoneurons, were injected into the tibial nerve 10–15 mm from the gastrocnemii muscles as the only neuron source for muscle reinnervation. The cells were stimulated immediately after transplantation for up to 1 h using protocols designed to examine differential effects due to pulse number, stimulation frequency, pattern, and duration. Electrical stimulation that included short rests and lasted for 1 h resulted in higher motor unit counts. Muscles with higher motor unit counts had more reinnervated fibers and were stronger. Denervated muscles had to be stimulated directly to evoke contractions. These results show that brief electrical stimulation of embryonic neurons, in vivo, has long-term effects on motor unit formation and muscle force. This muscle reinnervation provides the opportunity to use patterned electrical stimulation to produce functional movements. PMID:24848463

Patterns of motor activity in the isolated nerve cord of the octopus arm.

PubMed

Gutfreund, Yoram; Matzner, Henry; Flash, Tamar; Hochner, Binyamin

2006-12-01

The extremely flexible octopus arm provides a unique opportunity for studying movement control in a highly redundant motor system. We describe a novel preparation that allows analysis of the peripheral nervous system of the octopus arm and its interaction with the muscular and mechanosensory elements of the arm's intrinsic muscular system. First we examined the synaptic responses in muscle fibers to identify the motor pathways from the axial nerve cord of the arm to the surrounding musculature. We show that the motor axons project to the muscles via nerve roots originating laterally from the arm nerve cord. The motor field of each nerve is limited to the region where the nerve enters the arm musculature. The same roots also carry afferent mechanosensory information from the intrinsic muscle to the axial nerve cord. Next, we characterized the pattern of activity generated in the dorsal roots by electrically stimulating the axial nerve cord. The evoked activity, although far reaching and long lasting, cannot alone account for the arm extension movements generated by similar electrical stimulation. The mismatch between patterns of activity in the isolated cord and in an intact arm may stem from the involvement of mechanosensory feedback in natural arm extension.

46 CFR 178.325 - Intact stability requirements-monohull sailing vessels.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Intact stability requirements-monohull sailing vessels....325 Intact stability requirements—monohull sailing vessels. (a) As permitted by § 178.310(c) of this part, a monohull sailing vessel may demonstrate compliance with paragraphs (b) or (c) of this section...

46 CFR 178.320 - Intact stability requirements-non-sailing vessels.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Intact stability requirements-non-sailing vessels. 178.320 Section 178.320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER... Intact stability requirements—non-sailing vessels. (a) As permitted by § 178.310(c) of this part, the...

The EXCITE Trial: Predicting a Clinically Meaningful Motor Activity Log Outcome

PubMed Central

Park, Si-Woon; Wolf, Steven L.; Blanton, Sarah; Winstein, Carolee; Nichols-Larsen, Deborah S.

2013-01-01

Background and Objective This study determined which baseline clinical measurements best predicted a predefined clinically meaningful outcome on the Motor Activity Log (MAL) and developed a predictive multivariate model to determine outcome after 2 weeks of constraint-induced movement therapy (CIMT) and 12 months later using the database from participants in the Extremity Constraint Induced Therapy Evaluation (EXCITE) Trial. Methods A clinically meaningful CIMT outcome was defined as achieving higher than 3 on the MAL Quality of Movement (QOM) scale. Predictive variables included baseline MAL, Wolf Motor Function Test (WMFT), the sensory and motor portion of the Fugl-Meyer Assessment (FMA), spasticity, visual perception, age, gender, type of stroke, concordance, and time after stroke. Significant predictors identified by univariate analysis were used to develop the multivariate model. Predictive equations were generated and odds ratios for predictors were calculated from the multivariate model. Results Pretreatment motor function measured by MAL QOM, WMFT, and FMA were significantly associated with outcome immediately after CIMT. Pretreatment MAL QOM, WMFT, proprioception, and age were significantly associated with outcome after 12 months. Each unit of higher pretreatment MAL QOM score and each unit of faster pretreatment WMFT log mean time improved the probability of achieving a clinically meaningful outcome by 7 and 3 times at posttreatment, and 5 and 2 times after 12 months, respectively. Patients with impaired proprioception had a 20% probability of achieving a clinically meaningful outcome compared with those with intact proprioception. Conclusions Baseline clinical measures of motor and sensory function can be used to predict a clinically meaningful outcome after CIMT. PMID:18780883

The EXCITE Trial: Predicting a clinically meaningful motor activity log outcome.

PubMed

Park, Si-Woon; Wolf, Steven L; Blanton, Sarah; Winstein, Carolee; Nichols-Larsen, Deborah S

2008-01-01

This study determined which baseline clinical measurements best predicted a predefined clinically meaningful outcome on the Motor Activity Log (MAL) and developed a predictive multivariate model to determine outcome after 2 weeks of constraint-induced movement therapy (CIMT) and 12 months later using the database from participants in the Extremity Constraint Induced Therapy Evaluation (EXCITE) Trial. A clinically meaningful CIMT outcome was defined as achieving higher than 3 on the MAL Quality of Movement (QOM) scale. Predictive variables included baseline MAL, Wolf Motor Function Test (WMFT), the sensory and motor portion of the Fugl-Meyer Assessment (FMA), spasticity, visual perception, age, gender, type of stroke, concordance, and time after stroke. Significant predictors identified by univariate analysis were used to develop the multivariate model. Predictive equations were generated and odds ratios for predictors were calculated from the multivariate model. Pretreatment motor function measured by MAL QOM, WMFT, and FMA were significantly associated with outcome immediately after CIMT. Pretreatment MAL QOM, WMFT, proprioception, and age were significantly associated with outcome after 12 months. Each unit of higher pretreatment MAL QOM score and each unit of faster pretreatment WMFT log mean time improved the probability of achieving a clinically meaningful outcome by 7 and 3 times at posttreatment, and 5 and 2 times after 12 months, respectively. Patients with impaired proprioception had a 20% probability of achieving a clinically meaningful outcome compared with those with intact proprioception. Baseline clinical measures of motor and sensory function can be used to predict a clinically meaningful outcome after CIMT.

Sleep spindles: a physiological marker of age-related changes in gray matter in brain regions supporting motor skill memory consolidation.

PubMed

Fogel, Stuart; Vien, Catherine; Karni, Avi; Benali, Habib; Carrier, Julie; Doyon, Julien

2017-01-01

Sleep is necessary for the optimal consolidation of procedural learning, and in particular, for motor sequential skills. Motor sequence learning remains intact with age, but sleep-dependent consolidation is impaired, suggesting that memory deficits for procedural skills are specifically impacted by age-related changes in sleep. Age-related changes in spindles may be responsible for impaired motor sequence learning consolidation, but the morphological basis for this deficit is unknown. Here, we found that gray matter in the hippocampus and cerebellum was positively correlated with both sleep spindles and offline improvements in performance in young participants but not in older participants. These results suggest that age-related changes in gray matter in the hippocampus relate to spindles and may underlie age-related deficits in sleep-related motor sequence memory consolidation. In this way, spindles can serve as a biological marker for structural brain changes and the related memory deficits in older adults. Copyright © 2016 Elsevier Inc. All rights reserved.

Zernike phase contrast cryo-electron tomography of sodium-driven flagellar hook-basal bodies from Vibrio alginolyticus.

PubMed

Hosogi, Naoki; Shigematsu, Hideki; Terashima, Hiroyuki; Homma, Michio; Nagayama, Kuniaki

2011-01-01

Vibrio alginolyticus use flagella to swim. A flagellum consists of a filament, hook and basal body. The basal body is made up of a rod and several ring structures. This study investigates the structure of the T ring which is a unique component of the V. alginolyticus sodium ion-driven flagellar basal body. Using Zernike phase contrast (ZPC) cryo-electron tomography, we compared the 3D structures of purified hook-basal bodies (HBB) from a wild-type strain (KK148) and a deletion mutant lacking MotX and MotY (TH3), which are thought to form the T ring. ZPC images of HBBs had highly improved signal-to-noise ratio compared to conventional phase contrast images. We observed the outline of the HBBs from strains KK148 and TH3, and the TH3 mutant was missing its T ring. In the wild-type strain, the T ring was beneath the LP ring and seemed to form a ring shape with diameter of 32 nm. Copyright © 2010 Elsevier Inc. All rights reserved.

Thiols of flagellar proteins are essential for progressive motility in human spermatozoa.

PubMed

Cabrillana, María Eugenia; Monclus, María de Los Ángeles; Lancellotti, Tania Estefania Sáez; Boarelli, Paola Vanina; Vincenti, Amanda Edith; Fornés, Miguel Matias; Sanabria, Eduardo Alfredo; Fornés, Miguel Walter

2017-07-01

Male infertility is a disorder of the reproductive system defined by the failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse. The presence of low-motile or immotile spermatozoa is one of many causes of infertility; however, this observation provides little or no information regarding the pathogenesis of the malfunction. Good sperm motility depends on correct assembly of the sperm tail in the testis and efficient maturation during epididymal transit. Thiols of flagellar proteins, such as outer dense fibre protein 1 (ODF1), are oxidised to form disulfides during epididymal transit and the spermatozoa become motile. This study was designed to determine how oxidative changes in protein thiol status affect progressive motility in human spermatozoa. Monobromobimane (mBBr) was used as a specific thiol marker and disruptor of sperm progressive motility. When mBBr was blocked by dithiothreitol it did not promote motility changes. The analysis of mBBr-treated spermatozoa revealed a reduction of progressive motility and an increased number of spermatozoa with non-progressive motility without affecting ATP production. Laser confocal microscopy and western blot analysis showed that one of the mBBr-positive proteins reacted with an antibody to ODF1. Monobromobimane fluorescence intensity of the sperm tail was lower in normozoospermic than asthenozoospermic men, suggesting that thiol oxidation in spermatozoa of asthenozoospermic men is incomplete. Our findings indicate that mBBr affects the thiol status of ODF1 in human spermatozoa and interferes with progressive motility.

Vulnerability of ecosystems to climate change moderated by habitat intactness.

PubMed

Eigenbrod, Felix; Gonzalez, Patrick; Dash, Jadunandan; Steyl, Ilse

2015-01-01

The combined effects of climate change and habitat loss represent a major threat to species and ecosystems around the world. Here, we analyse the vulnerability of ecosystems to climate change based on current levels of habitat intactness and vulnerability to biome shifts, using multiple measures of habitat intactness at two spatial scales. We show that the global extent of refugia depends highly on the definition of habitat intactness and spatial scale of the analysis of intactness. Globally, 28% of terrestrial vegetated area can be considered refugia if all natural vegetated land cover is considered. This, however, drops to 17% if only areas that are at least 50% wilderness at a scale of 48×48 km are considered and to 10% if only areas that are at least 50% wilderness at a scale of 4.8×4.8 km are considered. Our results suggest that, in regions where relatively large, intact wilderness areas remain (e.g. Africa, Australia, boreal regions, South America), conservation of the remaining large-scale refugia is the priority. In human-dominated landscapes, (e.g. most of Europe, much of North America and Southeast Asia), focusing on finer scale refugia is a priority because large-scale wilderness refugia simply no longer exist. Action to conserve such refugia is particularly urgent since only 1 to 2% of global terrestrial vegetated area is classified as refugia and at least 50% covered by the global protected area network. © 2014 John Wiley & Sons Ltd.

CDKL5 regulates flagellar length and localizes to the base of the flagella in Chlamydomonas

PubMed Central

Tam, Lai-Wa; Ranum, Paul T.; Lefebvre, Paul A.

2013-01-01

The length of Chlamydomonas flagella is tightly regulated. Mutations in four genes—LF1, LF2, LF3, and LF4—cause cells to assemble flagella up to three times wild-type length. LF2 and LF4 encode protein kinases. Here we describe a new gene, LF5, in which null mutations cause cells to assemble flagella of excess length. The LF5 gene encodes a protein kinase very similar in sequence to the protein kinase CDKL5. In humans, mutations in this kinase cause a severe form of juvenile epilepsy. The LF5 protein localizes to a unique location: the proximal 1 μm of the flagella. The proximal localization of the LF5 protein is lost when genes that make up the proteins in the cytoplasmic length regulatory complex (LRC)—LF1, LF2, and LF3—are mutated. In these mutants LF5p becomes localized either at the distal tip of the flagella or along the flagellar length, indicating that length regulation involves, at least in part, control of LF5p localization by the LRC. PMID:23283985

Dynein-ADP as a force-generating intermediate revealed by a rapid reactivation of flagellar axoneme.

PubMed Central

Tani, T; Kamimura, S

1999-01-01

Fragmented flagellar axonemes of sand dollar spermatozoa were reactivated by rapid photolysis of caged ATP. After a time lag of 10 ms, axonemes treated with protease started sliding disintegration. Axonemes without protease digestion started nanometer-scale high-frequency oscillation after a similar time lag. Force development in the sliding disintegration was measured with a flexible glass needle and its time course was corresponded well to that of the dynein-ADP intermediate production estimated using kinetic rates previously reported. However, with a high concentration ( approximately 80 microM) of vanadate, which binds to the dynein-ADP intermediate and forms a stable complex of dynein-ADP-vanadate, the time course of force development in sliding disintegration was not affected at all. In the case of high frequency oscillation, the time lag to start the oscillation, the initial amplitude, and the initial frequency were not affected by vanadate, though the oscillation once started was damped more quickly at higher concentrations of vanadate. These results suggest that during the initial turnover of ATP hydrolysis, force generation of dynein is not blocked by vanadate. A vanadate-insensitive dynein-ADP is postulated as a force-generating intermediate. PMID:10465762

Altered neuronal activity in the primary motor cortex and globus pallidus after dopamine depletion in rats.

PubMed

Wang, Min; Li, Min; Geng, Xiwen; Song, Zhimin; Albers, H Elliott; Yang, Maoquan; Zhang, Xiao; Xie, Jinlu; Qu, Qingyang; He, Tingting

2015-01-15

The involvement of dopamine (DA) neuron loss in the etiology of Parkinson's disease has been well documented. The neural mechanisms underlying the effects of DA loss and the resultant motor dysfunction remain unknown. To gain insights into how loss of DA disrupts the electrical processes in the cortico-subcortical network, the present study explores the effects of DA neuron depletion on electrical activity in the primary motor cortex (M1), on the external and the internal segment of the globus pallidus (GPe and GPi respectively), and on their temporal relationships. Comparison of local field potentials (LFPs) in these brain regions from unilateral hemispheric DA neuron depleted rats and neurologically intact rats revealed that the spectrum power of LFPs in 12-70Hz (for M1, and GPe) and in 25-40Hz (for GPi) was significantly greater in the DA depleted rats than that in the control group. These changes were associated with a shortening of latency in LFP activities between M1 and GPe, from several hundred milliseconds in the intact animals to close to zero in the DA depleted animals. LFP oscillations in M1 were significantly more synchronized with those in GPe in the DA depleted rats compared with those in the control rats. By contrast, the synchronization of oscillation in LFP activities between M1 and GPi did not differ between the DA depleted and intact rats. Not surprisingly, rats that had DA neuron depletion spent more time along the ladder compared with the control rats. These data suggest that enhanced oscillatory activity and increased synchronization of LFPs may contribute to movement impairment in the rat model of Parkinson's disease. Copyright © 2014 Elsevier B.V. All rights reserved.

Initial characterization of the FlgE hook high molecular weight complex of Borrelia burgdorferi.

PubMed

Miller, Kelly A; Motaleb, Md A; Liu, Jun; Hu, Bo; Caimano, Melissa J; Miller, Michael R; Charon, Nyles W

2014-01-01

The spirochete periplasmic flagellum has many unique attributes. One unusual characteristic is the flagellar hook. This structure serves as a universal joint coupling rotation of the membrane-bound motor to the flagellar filament. The hook is comprised of about 120 FlgE monomers, and in most bacteria these structures readily dissociate to monomers (∼ 50 kDa) when treated with heat and detergent. However, in spirochetes the FlgE monomers form a large mass of over 250 kDa [referred to as a high molecular weight complex (HMWC)] that is stable to these and other denaturing conditions. In this communication, we examined specific aspects with respect to the formation and structure of this complex. We found that the Lyme disease spirochete Borrelia burgdorferi synthesized the HMWC throughout the in vitro growth cycle, and also in vivo when implanted in dialysis membrane chambers in rats. The HMWC was stable to formic acid, which supports the concept that the stability of the HMWC is dependent on covalent cross-linking of individual FlgE subunits. Mass spectrometry analysis of the HMWC from both wild type periplasmic flagella and polyhooks from a newly constructed ΔfliK mutant indicated that other proteins besides FlgE were not covalently joined to the complex, and that FlgE was the sole component of the complex. In addition, mass spectrometry analysis also indicated that the HMWC was composed of a polymer of the FlgE protein with both the N- and C-terminal regions remaining intact. These initial studies set the stage for a detailed characterization of the HMWC. Covalent cross-linking of FlgE with the accompanying formation of the HMWC we propose strengthens the hook structure for optimal spirochete motility.

Initial Characterization of the FlgE Hook High Molecular Weight Complex of Borrelia burgdorferi

PubMed Central

Miller, Kelly A.; Motaleb, Md. A.; Liu, Jun; Hu, Bo; Caimano, Melissa J.; Miller, Michael R.; Charon, Nyles W.

2014-01-01

The spirochete periplasmic flagellum has many unique attributes. One unusual characteristic is the flagellar hook. This structure serves as a universal joint coupling rotation of the membrane-bound motor to the flagellar filament. The hook is comprised of about 120 FlgE monomers, and in most bacteria these structures readily dissociate to monomers (∼ 50 kDa) when treated with heat and detergent. However, in spirochetes the FlgE monomers form a large mass of over 250 kDa [referred to as a high molecular weight complex (HMWC)] that is stable to these and other denaturing conditions. In this communication, we examined specific aspects with respect to the formation and structure of this complex. We found that the Lyme disease spirochete Borrelia burgdorferi synthesized the HMWC throughout the in vitro growth cycle, and also in vivo when implanted in dialysis membrane chambers in rats. The HMWC was stable to formic acid, which supports the concept that the stability of the HMWC is dependent on covalent cross-linking of individual FlgE subunits. Mass spectrometry analysis of the HMWC from both wild type periplasmic flagella and polyhooks from a newly constructed ΔfliK mutant indicated that other proteins besides FlgE were not covalently joined to the complex, and that FlgE was the sole component of the complex. In addition, mass spectrometry analysis also indicated that the HMWC was composed of a polymer of the FlgE protein with both the N- and C-terminal regions remaining intact. These initial studies set the stage for a detailed characterization of the HMWC. Covalent cross-linking of FlgE with the accompanying formation of the HMWC we propose strengthens the hook structure for optimal spirochete motility. PMID:24859001

Ipsilateral corticotectal projections from the primary, premotor and supplementary motor cortical areas in adult macaque monkeys: a quantitative anterograde tracing study

PubMed Central

Fregosi, Michela; Rouiller, Eric M.

2018-01-01

The corticotectal projection from cortical motor areas is one of several descending pathways involved in the indirect control of spinal motoneurons. In non-human primates, previous studies reported that cortical projections to the superior colliculus originated from the premotor cortex and the primary motor cortex, whereas no projection originated from the supplementary motor area. The aim of the present study was to investigate and compare the properties of corticotectal projections originating from these three cortical motor areas in intact adult macaques (n=9). The anterograde tracer BDA was injected into one of these cortical areas in each animal. Individual axonal boutons, both en passant and terminaux, were charted and counted in the different layers of the ipsilateral superior colliculus. The data confirmed the presence of strong corticotectal projections from the premotor cortex. A new observation was that strong corticotectal projections were also found to originate from the supplementary motor area (its proper division). The corticotectal projection from the primary motor cortex was quantitatively less strong than that from either the premotor or supplementary motor areas. The corticotectal projection from each motor area was directed mainly to the deep layer of the superior colliculus, although its intermediate layer was also a consistent target of fairly dense terminations. The strong corticotectal projections from non-primary motor areas are in position to influence the preparation and planning of voluntary movements. PMID:28921678

Xenopus egg cytoplasm with intact actin.

PubMed

Field, Christine M; Nguyen, Phuong A; Ishihara, Keisuke; Groen, Aaron C; Mitchison, Timothy J

2014-01-01

We report optimized methods for preparing Xenopus egg extracts without cytochalasin D, that we term "actin-intact egg extract." These are undiluted egg cytoplasm that contains abundant organelles, and glycogen which supplies energy, and represents the least perturbed cell-free cytoplasm preparation we know of. We used this system to probe cell cycle regulation of actin and myosin-II dynamics (Field et al., 2011), and to reconstitute the large, interphase asters that organize early Xenopus embryos (Mitchison et al., 2012; Wühr, Tan, Parker, Detrich, & Mitchison, 2010). Actin-intact Xenopus egg extracts are useful for analysis of actin dynamics, and interaction of actin with other cytoplasmic systems, in a cell-free system that closely mimics egg physiology, and more generally for probing the biochemistry and biophysics of the egg, zygote, and early embryo. Detailed protocols are provided along with assays used to check cell cycle state and tips for handling and storing undiluted egg extracts. © 2014 Elsevier Inc. All rights reserved.

Effect of motor limitations on the expression of aggressiveness among adolescents.

PubMed

Tripković, Mara; Matijević, Valentina; Marković, Hrvoje; Ercegovi, Nela

2015-03-01

This study examined how motor limitations in terms of reduced possibilities to move influence aggression, starting from the fact that motor skills and movement have an important place in the expression of aggression, as well as the tendency of adolescents to "body language". Adolescent with motor deficit is hindered in gaining experience of one's own body, which is reflected in the formation of complete experience of himself, or constitution of the self. In many of the functions of motor skills and movement aggression has a significant place that we wanted to determine without deeper analysis of whether the origin of aggression is instinctive or it is always just the result of frustration. The sample on which testing was performed consisted of 100 randomly selected subjects of both genders aged 16-18 years. Fifty subjects had motor limitations due to illness or injury, and another fifty subjects had intact motor functions. The study used three instruments: 1) A-87 questionnaire for aggressiveness examination; 2) structured interview; and 3) protocol for observation under natural conditions. Results of the analysis of data obtained in total score, as well as in all five subscales of the A-87 questionnaire for aggressiveness examination showed that the two groups were not significantly different. The results obtained by structured interview showed the adolescents with motor limitations to demonstrate greater verbal aggressiveness, then latent physical aggressiveness. A statistically significant between-group difference was obtained on the factor of self-destructiveness, which implies that adolescents with motor limitations are somewhat more self-destructive compared to those in control group. From the results obtained by the protocol for systematic observation in natural conditions, it was evident that there were significant differences on most of perceptual conducts between control and experimental group, whereby adolescents with motor limitations were more

Studies of sensory and motor cortex physiology: with observations on akinesia in Parkinson's disease.

PubMed

Hallett, M; Cohen, L G; Bierner, S M

1991-01-01

Magnetic stimulation of the brain can be used to investigate sensory and motor physiology and pathophysiology in intact humans. Although uncommon, it is possible for magnetic stimulation over sensorimotor cortex to produce paresthesis. With magnetic stimulation, it is also possible to block the conscious sensation of an electrical shock delivered to the index finger. The magnetic stimulus must be delivered in the interval from 300 msec before to 200 msec after the cutaneous shock and must be delivered over the contralateral hand region of the sensorimotor cortex. In a reaction time situation, the expected voluntary response may be delayed by a magnetic stimulus delivered over the sensorimotor cortex just before the movement. With the use of a relatively weak magnetic stimulus that does not produce a motor evoked potential (MEP) when the body part is at rest, but that will produce a response when the body part is activated, the reaction time can be divided into two periods. In the first period, there is no MEP and the motor cortex remains 'inexcitable'. In the second period, there is a gradual increase in MEP amplitude even though the voluntary electromyographic activity has not yet appeared. This 'excitable' period indicates the activation of motor cortex before the motor command is delivered. Application of this technique to the analysis of prolonged reaction time (akinesia) in patients with Parkinson's disease shows that the excitable period is prolonged. This describes the mechanism underlying the difficulty in the generation of a motor command in these patients.

Bimanual coupling paradigm as an effective tool to investigate productive behaviors in motor and body awareness impairments.

PubMed

Garbarini, Francesca; Pia, Lorenzo

2013-11-05

When humans move simultaneously both hands strong coupling effects arise and neither of the two hands is able to perform independent actions. It has been suggested that such motor constraints are tightly linked to action representation rather than to movement execution. Hence, bimanual tasks can represent an ideal experimental tool to investigate internal motor representations in those neurological conditions in which the movement of one hand is impaired. Indeed, any effect on the "moving" (healthy) hand would be caused by the constraints imposed by the ongoing motor program of the 'impaired' hand. Here, we review recent studies that successfully utilized the above-mentioned paradigms to investigate some types of productive motor behaviors in stroke patients. Specifically, bimanual tasks have been employed in left hemiplegic patients who report illusory movements of their contralesional limbs (anosognosia for hemiplegia). They have also been administered to patients affected by a specific monothematic delusion of body ownership, namely the belief that another person's arm and his/her voluntary action belong to them. In summary, the reviewed studies show that bimanual tasks are a simple and valuable experimental method apt to reveal information about the motor programs of a paralyzed limb. Therefore, it can be used to objectively examine the cognitive processes underpinning motor programming in patients with different delusions of motor behavior. Additionally, it also sheds light on the mechanisms subserving bimanual coordination in the intact brain suggesting that action representation might be sufficient to produce these effects.

A Comparison of Bacterial Composition in Diabetic Ulcers and Contralateral Intact Skin

PubMed Central

Gontcharova, Viktoria; Youn, Eunseog; Sun, Yan; Wolcott, Randall D; Dowd, Scot E

2010-01-01

An extensive portion of the healthcare budget is allocated to chronic human infection. Chronic wounds in particular are a major contributor to this financial burden. Little is known about the types of bacteria which may contribute to the chronicity, biofilm and overall bioburden of the wound itself. In this study we compare the bacteriology of wounds and associated intact skin. Wound and paired intact skin swabs (from a contralateral location) were collected. The bacterial diversity was determined using bacterial Tag-encoded FLX amplicon pyrosequencing (bTEFAP). Diversity analysis showed intact skin to be significantly more diverse than wounds on both the species and genus levels (3% and 5% divergence). Furthermore, wounds show heightened levels of anaerobic bacteria, like Peptoniphilus, Finegoldia, and Anaerococcus, and other detrimental genera such as Corynebacterium and Staphylococcus. Although some of these and other bacterial genera were found to be common between intact skin and wounds, notable opportunistic wound pathogens were found at lower levels in intact skin. Principal Component Analysis demonstrated a clear separability of the two groups. The findings of the study not only greatly support the hypothesis of differing bacterial composition of intact skin and wounds, but also contribute additional insight into the ecology of skin and wound microflora. The increased diversity and lowered levels of opportunistic pathogens found in skin make the system highly distinguishable from wounds. PMID:20461221

Modified madigan prostatectomy: a procedure preserved prostatic urethra intact.

PubMed

Lu, Jun; Ye, Zhangqun; Hu, Weilie

2005-01-01

A total of 92 patients with benign prostatic hyperplasia (BPH) were subjected to modified Madigan prostatectomy (MPC) for a much satisfactory effect in open prostatectomy surgery. Exposing anterior prostatic urethra near the bladder neck and conjunct cystotomy modified the MPC procedure. This modified procedure preserved prostatic urethra intact and could also deal with intracystic lesions at the same time. The intact of prostatic urethra was kept completely or largely in 86 cases. The amount of blood loss during modified procedure was less. The mean operative time was 105 min. Seventy patients had been followed up for 3-24 months. The postoperative average Qmax was 19. 2 ml/s. The cystourethrography revealed that the urethra and bladder neck were intact in 10 patients postoperatively. Furthermore, the prostatic urethra was obviously wider after modified MPC. The modified MPC can reduce the occurrence of urethra injury and enlarge the MPC indications. The modified technique is easy to perform with less complications and much satisfactory clinical result.

Arraying of intact liposomes into chemically functionalized microwells.

PubMed

Kalyankar, Nikhil D; Sharma, Manoj K; Vaidya, Shyam V; Calhoun, David; Maldarelli, Charles; Couzis, Alexander; Gilchrist, Lane

2006-06-06

Here, we describe a protocol to bind individual, intact phospholipid bilayer liposomes, which are on the order of 1 microm in diameter, in microwells etched in a regular array on a silicon oxide substrate. The diameter of the wells is on the order of the liposome diameter, so only one liposome is located in each well. The background of the silicon oxide surface is functionalized with a PEG oligomer using the contact printing of a PEG silane to present a surface that resists the adsorption of proteins, lipid material, and liposomes. The interiors of the wells are functionalized with an aminosilane to facilitate the conjugation of biotin, which is then bound to Neutravidin. The avidin-coated well interiors bind the liposomes whose surfaces contain biotinylated lipids. The specific binding of the liposomes to the surface using the biotin-avidin linkage, together with the resistant nature of the background and the physical confinement of the wells, allows the liposomes to remain intact and to not unravel, rupture, and fuse onto the surface. We demonstrate this intact arraying using confocal laser scanning microscopy of fluorophores specifically tagging the microwells, the lipid bilayer, and the aqueous interior of the liposome.

Unique ATPase site architecture triggers cis-mediated synchronized ATP binding in heptameric AAA+-ATPase domain of flagellar regulatory protein FlrC.

PubMed

Dey, Sanjay; Biswas, Maitree; Sen, Udayaditya; Dasgupta, Jhimli

2015-04-03

Bacterial enhancer-binding proteins (bEBPs) oligomerize through AAA(+) domains and use ATP hydrolysis-driven energy to isomerize the RNA polymerase-σ(54) complex during transcriptional initiation. Here, we describe the first structure of the central AAA(+) domain of the flagellar regulatory protein FlrC (FlrC(C)), a bEBP that controls flagellar synthesis in Vibrio cholerae. Our results showed that FlrC(C) forms heptamer both in nucleotide (Nt)-free and -bound states without ATP-dependent subunit remodeling. Unlike the bEBPs such as NtrC1 or PspF, a novel cis-mediated "all or none" ATP binding occurs in the heptameric FlrC(C), because constriction at the ATPase site, caused by loop L3 and helix α7, restricts the proximity of the trans-protomer required for Nt binding. A unique "closed to open" movement of Walker A, assisted by trans-acting "Glu switch" Glu-286, facilitates ATP binding and hydrolysis. Fluorescence quenching and ATPase assays on FlrC(C) and mutants revealed that although Arg-349 of sensor II, positioned by trans-acting Glu-286 and Tyr-290, acts as a key residue to bind and hydrolyze ATP, Arg-319 of α7 anchors ribose and controls the rate of ATP hydrolysis by retarding the expulsion of ADP. Heptameric state of FlrC(C) is restored in solution even with the transition state mimicking ADP·AlF3. Structural results and pulldown assays indicated that L3 renders an in-built geometry to L1 and L2 causing σ(54)-FlrC(C) interaction independent of Nt binding. Collectively, our results underscore a novel mechanism of ATP binding and σ(54) interaction that strives to understand the transcriptional mechanism of the bEBPs, which probably interact directly with the RNA polymerase-σ(54) complex without DNA looping. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Development of Predictive Algorithms for Pre-Treatment Motor Deficit and 90-Day Mortality in Spinal Epidural Abscess.

PubMed

Shah, Akash A; Ogink, Paul T; Harris, Mitchel B; Schwab, Joseph H

2018-06-20

Spinal epidural abscess is a high-risk condition that can lead to paralysis or death. It would be of clinical and prognostic utility to identify which subset of patients with spinal epidural abscess is likely to develop a motor deficit or die within 90 days of discharge. We identified all patients ≥18 years of age who were admitted to our hospital system with a diagnosis of spinal epidural abscess during the period of 1993 to 2016. Explanatory variables were collected retrospectively. Bivariate and multivariable logistic regression was performed using these variables to identify independent predictors of motor deficit and 90-day mortality. Nomograms were then constructed to quantify the risk of these outcomes. Of the 1,053 patients we identified with spinal epidural abscess, 362 presented with motor weakness. One hundred and thirty-four patients died within 90 days of discharge, inclusive of those who died during hospitalization. Multivariable logistic regression yielded 8 independent predictors of pre-treatment motor deficit and 8 independent predictors of 90-day mortality. We constructed nomograms that generated a probability of pre-treatment motor deficit or 90-day mortality on the basis of the presence of these factors. By quantifying the risk of pre-treatment motor deficit and 90-day mortality, our nomograms may provide useful prognostic information for the treatment team. Timely treatment of neurologically intact patients with a high risk of developing a motor deficit is necessary to avoid residual motor weakness and improve survival. Therapeutic Level IV. See Instructions for Authors for a complete description of Levels of Evidence.

Motor control for a brushless DC motor

NASA Technical Reports Server (NTRS)

Peterson, William J. (Inventor); Faulkner, Dennis T. (Inventor)

1985-01-01

This invention relates to a motor control system for a brushless DC motor having an inverter responsively coupled to the motor control system and in power transmitting relationship to the motor. The motor control system includes a motor rotor speed detecting unit that provides a pulsed waveform signal proportional to rotor speed. This pulsed waveform signal is delivered to the inverter to thereby cause an inverter fundamental current waveform output to the motor to be switched at a rate proportional to said rotor speed. In addition, the fundamental current waveform is also pulse width modulated at a rate proportional to the rotor speed. A fundamental current waveform phase advance circuit is controllingly coupled to the inverter. The phase advance circuit is coupled to receive the pulsed waveform signal from the motor rotor speed detecting unit and phase advance the pulsed waveform signal as a predetermined function of motor speed to thereby cause the fundamental current waveform to be advanced and thereby compensate for fundamental current waveform lag due to motor winding reactance which allows the motor to operate at higher speeds than the motor is rated while providing optimal torque and therefore increased efficiency.

Negative regulatory loci coupling flagellin synthesis to flagellar assembly in Salmonella typhimurium.

PubMed Central

Gillen, K L; Hughes, K T

1991-01-01

The complex regulation of flagellin gene expression in Salmonella typhimurium was characterized in vivo by using lac transcriptional fusions to the two flagellin structural genes (fliC [H1] and fljB [H2]). Phase variation was measured as the rate of switching of flagellin gene expression. Switching frequencies varied from 1/500 per cell per generation to 1/10,000 per cell per generation depending on the particular insertion and the direction of switching. There is a 4- to 20-fold bias in favor of switching from the fljB(On) to the fljB(Off) orientation. Random Tn10dTc insertions were isolated which failed to express flagellin. While most of these insertions mapped to loci known to be required for flagellin expression, several new loci were identified. The presence of functional copies of all of the genes responsible for complete flagellar assembly, except the hook-associated proteins (flgK, flgL, and fliD gene products), were required for expression of the fliC or fljB flagellin genes. Two novel loci involved in negative regulation of fliC and fljB in fla mutant backgrounds were identified. One of these loci, designated the flgR locus, mapped to the flg operon at 23 min on the Salmonella linkage map. An flgR insertion mutation resulted in relief of repression of the fliC and fljB genes in all fla mutant backgrounds except for mutants in the positive regulatory loci (flhC, flhD, and fliA genes). PMID:1848842

The Function and Organization of the Motor System Controlling Flight Maneuvers in Flies.

PubMed

Lindsay, Theodore; Sustar, Anne; Dickinson, Michael

2017-02-06

Animals face the daunting task of controlling their limbs using a small set of highly constrained actuators. This problem is particularly demanding for insects such as Drosophila, which must adjust wing motion for both quick voluntary maneuvers and slow compensatory reflexes using only a dozen pairs of muscles. To identify strategies by which animals execute precise actions using sparse motor networks, we imaged the activity of a complete ensemble of wing control muscles in intact, flying flies. Our experiments uncovered a remarkably efficient logic in which each of the four skeletal elements at the base of the wing are equipped with both large phasically active muscles capable of executing large changes and smaller tonically active muscles specialized for continuous fine-scaled adjustments. Based on the responses to a broad panel of visual motion stimuli, we have developed a model by which the motor array regulates aerodynamically functional features of wing motion. VIDEO ABSTRACT. Copyright © 2017 Elsevier Ltd. All rights reserved.

Calmodulin in complex with the first IQ motif of myosin-5a functions as an intact calcium sensor

PubMed Central

Shen, Mei; Zhang, Ning; Zheng, Sanduo; Zhang, Wen-Bo; Zhang, Hai-Man; Lu, Zekuan; Su, Qian Peter; Sun, Yujie; Li, Xiang-dong

2016-01-01

The motor function of vertebrate myosin-5a is inhibited by its tail in a Ca2+-dependent manner. We previously demonstrated that the calmodulin (CaM) bound to the first isoleucine-glutamine (IQ) motif (IQ1) of myosin-5a is responsible for the Ca2+-dependent regulation of myosin-5a. We have solved the crystal structure of a truncated myosin-5a containing the motor domain and IQ1 (MD-IQ1) complexed with Ca2+-bound CaM (Ca2+-CaM) at 2.5-Å resolution. Compared with the structure of the MD-IQ1 complexed with essential light chain (an equivalent of apo-CaM), MD-IQ1/Ca2+-CaM displays large conformational differences in IQ1/CaM and little difference in the motor domain. In the MD-IQ1/Ca2+-CaM structure, the N-lobe and the C-lobe of Ca2+-CaM adopt an open conformation and grip the C-terminal and the N-terminal portions of the IQ1, respectively. Remarkably, the interlobe linker of CaM in IQ1/Ca2+-CaM is in a position opposite that in IQ1/apo-CaM, suggesting that CaM flip-flops relative to the IQ1 during the Ca2+ transition. We demonstrated that CaM continuously associates with the IQ1 during the Ca2+ transition and that the binding of CaM to IQ1 increases Ca2+ affinity and substantially changes the kinetics of the Ca2+ transition, suggesting that the IQ1/CaM complex functions as an intact Ca2+ sensor responding to distinct calcium signals. PMID:27647889

Calmodulin in complex with the first IQ motif of myosin-5a functions as an intact calcium sensor.

PubMed

Shen, Mei; Zhang, Ning; Zheng, Sanduo; Zhang, Wen-Bo; Zhang, Hai-Man; Lu, Zekuan; Su, Qian Peter; Sun, Yujie; Ye, Keqiong; Li, Xiang-Dong

2016-10-04

The motor function of vertebrate myosin-5a is inhibited by its tail in a Ca 2+ -dependent manner. We previously demonstrated that the calmodulin (CaM) bound to the first isoleucine-glutamine (IQ) motif (IQ1) of myosin-5a is responsible for the Ca 2+ -dependent regulation of myosin-5a. We have solved the crystal structure of a truncated myosin-5a containing the motor domain and IQ1 (MD-IQ1) complexed with Ca 2+ -bound CaM (Ca 2+ -CaM) at 2.5-Å resolution. Compared with the structure of the MD-IQ1 complexed with essential light chain (an equivalent of apo-CaM), MD-IQ1/Ca 2+ -CaM displays large conformational differences in IQ1/CaM and little difference in the motor domain. In the MD-IQ1/Ca 2+ -CaM structure, the N-lobe and the C-lobe of Ca 2+ -CaM adopt an open conformation and grip the C-terminal and the N-terminal portions of the IQ1, respectively. Remarkably, the interlobe linker of CaM in IQ1/Ca 2+ -CaM is in a position opposite that in IQ1/apo-CaM, suggesting that CaM flip-flops relative to the IQ1 during the Ca 2+ transition. We demonstrated that CaM continuously associates with the IQ1 during the Ca 2+ transition and that the binding of CaM to IQ1 increases Ca 2+ affinity and substantially changes the kinetics of the Ca 2+ transition, suggesting that the IQ1/CaM complex functions as an intact Ca 2+ sensor responding to distinct calcium signals.

Tidal stretches do not modulate responsiveness of intact airways in vitro

PubMed Central

Szabo, Thomas L.; Suki, Béla; Lutchen, Kenneth R.

2010-01-01

Studies on isolated tracheal airway smooth muscle (ASM) strips have shown that length/force fluctuations, similar to those likely occurring during breathing, will mitigate ASM contractility. These studies conjecture that, solely by reducing length oscillations on a healthy, intact airway, one can create airway hyperresponsiveness, but this has never been explicitly tested. The intact airway has additional complexities of geometry and structure that may impact its relevance to isolated ASM strips. We examined the role of transmural pressure (Ptm) fluctuations of physiological amplitudes on the responsiveness of an intact airway. We developed an integrated system utilizing ultrasound imaging to provide real-time measurements of luminal radius and wall thickness over the full length of an intact airway (generation 10 and below) during Ptm oscillations. First, airway constriction dynamics to cumulative acetylcholine (ACh) doses (10−7 to 10−3 M) were measured during static and dynamic Ptm protocols. Regardless of the breathing pattern, the Ptm oscillation protocols were ineffective in reducing the net level of constriction for any ACh dose, compared with the static control (P = 0.225–0.793). Next, Ptm oscillations of increasing peak-to-peak amplitude were applied subsequent to constricting intact airways under static conditions (5.0-cmH2O Ptm) with a moderate ACh dose (10−5 M). Peak-to-peak Ptm oscillations ≤5.0 cmH2O resulted in no statistically significant bronchodilatory response (P = 0.429 and 0.490). Larger oscillations (10 cmH2O, peak to peak) produced modest dilation of 4.3% (P = 0.009). The lack of modulation of airway responsiveness by Ptm oscillations in intact, healthy airways suggests that ASM level mechanisms alone may not be the sole determinant of airway responsiveness. PMID:20431023

Swimming Motility Mediates the Formation of Neutrophil Extracellular Traps Induced by Flagellated Pseudomonas aeruginosa

PubMed Central

Sil, Payel; Chassaing, Benoit; Yoo, Dae-goon; Gewirtz, Andrew T.; Goldberg, Joanna B.; McCarter, Linda L.; Rada, Balázs

2016-01-01

Pseudomonas aeruginosa is an opportunistic pathogen causing severe infections often characterized by robust neutrophilic infiltration. Neutrophils provide the first line of defense against P. aeruginosa. Aside from their defense conferred by phagocytic activity, neutrophils also release neutrophil extracellular traps (NETs) to immobilize bacteria. Although NET formation is an important antimicrobial process, the details of its mechanism are largely unknown. The identity of the main components of P. aeruginosa responsible for triggering NET formation is unclear. In this study, our focus was to identify the main bacterial factors mediating NET formation and to gain insight into the underlying mechanism. We found that P. aeruginosa in its exponential growth phase promoted strong NET formation in human neutrophils while its NET-inducing ability dramatically decreased at later stages of bacterial growth. We identified the flagellum as the primary component of P. aeruginosa responsible for inducing NET extrusion as flagellum-deficient bacteria remained seriously impaired in triggering NET formation. Purified P. aeruginosa flagellin, the monomeric component of the flagellum, does not stimulate NET formation in human neutrophils. P. aeruginosa-induced NET formation is independent of the flagellum-sensing receptors TLR5 and NLRC4 in both human and mouse neutrophils. Interestingly, we found that flagellar motility, not flagellum binding to neutrophils per se, mediates NET release induced by flagellated bacteria. Immotile, flagellar motor-deficient bacterial strains producing paralyzed flagella did not induce NET formation. Forced contact between immotile P. aeruginosa and neutrophils restored their NET-inducing ability. Both the motAB and motCD genetic loci encoding flagellar motor genes contribute to maximal NET release; however the motCD genes play a more important role. Phagocytosis of P. aeruginosa and superoxide production by neutrophils were also largely dependent upon

Morphologic changes in the mesolimbic pathway in Parkinson's disease motor subtypes.

PubMed

Nyberg, Eric M; Tanabe, Jody; Honce, Justin M; Krmpotich, Theodore; Shelton, Erika; Hedeman, Jessica; Berman, Brian D

2015-05-01

Parkinson's disease (PD) is a common neurodegenerative disorder associated with gray matter atrophy. Cortical atrophy patterns may further help distinguish between PD motor subtypes. Comparable differences in subcortical volumes have not been found. Twenty-one cognitively intact and treated PD patients, including 12 tremor dominant (TD) subtype, Nine postural instability gait dominant (PIGD) subtype, and 20 matched healthy control subjects underwent 3.0 T high-resolution structural MRI scanning. Subcortical volumetric analysis was performed using FreeSurfer and shape analysis was performed with FIRST to assess for differences between PD patients and controls and between PD subtypes. No significant differences in subcortical volumes were found between motor PD subtypes, but comparing grouped PD patients with controls revealed a significant increase in hippocampal volume in PD patients (p = 0.03). A significant shape difference was detected in the right nucleus accumbens (NAcc) between PD and controls and between motor subtypes. Shape differences were driven by positive deviations in the TD subtype. Correlation analysis revealed a trend between hippocampal volume and decreasing MDS-UPDRS (p = 0.06). While no significant differences in subcortical volumes between PD motor subtypes were found, increased hippocampal volumes were observed in PD patients compared to controls. Right NAcc shape differences in PD patients were driven by changes in the TD subtype. These unexpected findings may be related to the effects of chronic dopaminergic replacement on the mesolimbic pathway. Further studies are needed to replicate and determine the clinical significance of such morphologic changes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mechanism of autoregulation in the intact kidney.

DOT National Transportation Integrated Search

1963-12-01

The mechanism of renal autoregulation is unclear. The subject of the present investigation is the mechanism of autoregulation of blood flow in the intact kidney. The left kidney of the anesthetized dog was exposed via a flank approach. Renal venous o...

Self-etching adhesive on intact enamel, with and without pre-etching.

PubMed

Devarasa, G M; Subba Reddy, V V; Chaitra, N L; Swarna, Y M

2012-05-01

Bond strengths of composite resin to enamel using self-etch adhesive (SEA) Clearfil SE bond system on intact enamel and enamel pre-etched with phosphoric acid were compared. The objective was to determine if the pre-etching would increase the bond strengths of the SEA systems to intact enamel and to evaluate the effect of pre-etching on bond formation of self-etch adhesives on intact enamel. Labial surfaces of 40 caries free permanent upper central and lateral incisors were cleaned, sectioned of their roots. All specimens were mounted on acrylic block and divided randomly into four groups. In two groups the application of self-etch adhesive, Clearfil SE bond was carried as per manufacturer's instructions, composite cylinders were built, whereas in the other two groups, 37% phosphoric acid etching was done before the application of self-etching adhesives. Then the resin tags were analyzed using scanning electron microscope and shear bond strength was measured using Instron universal testing machine. When phosphoric acid was used, there was significant increase in the depth of penetration of resin tags and in the Shear Bond Strength of composite to enamel. The results indicate that out of both treatment groups, pre-etching the intact enamel with 37% phosphoric acid resulted in formation of longer resin tags and higher depth of penetration of resin tags of the Clearfil SE bond, and attaining higher bond strength of the Clearfil SE bond to intact enamel. Copyright © 2011 Wiley Periodicals, Inc.

Intact mirror mechanisms for automatic facial emotions in children and adolescents with autism spectrum disorder.

PubMed

Schulte-Rüther, Martin; Otte, Ellen; Adigüzel, Kübra; Firk, Christine; Herpertz-Dahlmann, Beate; Koch, Iring; Konrad, Kerstin

2017-02-01

It has been suggested that an early deficit in the human mirror neuron system (MNS) is an important feature of autism. Recent findings related to simple hand and finger movements do not support a general dysfunction of the MNS in autism. Studies investigating facial actions (e.g., emotional expressions) have been more consistent, however, mostly relied on passive observation tasks. We used a new variant of a compatibility task for the assessment of automatic facial mimicry responses that allowed for simultaneous control of attention to facial stimuli. We used facial electromyography in 18 children and adolescents with Autism spectrum disorder (ASD) and 18 typically developing controls (TDCs). We observed a robust compatibility effect in ASD, that is, the execution of a facial expression was facilitated if a congruent facial expression was observed. Time course analysis of RT distributions and comparison to a classic compatibility task (symbolic Simon task) revealed that the facial compatibility effect appeared early and increased with time, suggesting fast and sustained activation of motor codes during observation of facial expressions. We observed a negative correlation of the compatibility effect with age across participants and in ASD, and a positive correlation between self-rated empathy and congruency for smiling faces in TDC but not in ASD. This pattern of results suggests that basic motor mimicry is intact in ASD, but is not associated with complex social cognitive abilities such as emotion understanding and empathy. Autism Res 2017, 10: 298-310. © 2016 International Society for Autism Research, Wiley Periodicals, Inc. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Simultaneous Brain–Cervical Cord fMRI Reveals Intrinsic Spinal Cord Plasticity during Motor Sequence Learning

PubMed Central

Cohen-Adad, Julien; Marchand-Pauvert, Veronique; Benali, Habib; Doyon, Julien

2015-01-01

The spinal cord participates in the execution of skilled movements by translating high-level cerebral motor representations into musculotopic commands. Yet, the extent to which motor skill acquisition relies on intrinsic spinal cord processes remains unknown. To date, attempts to address this question were limited by difficulties in separating spinal local effects from supraspinal influences through traditional electrophysiological and neuroimaging methods. Here, for the first time, we provide evidence for local learning-induced plasticity in intact human spinal cord through simultaneous functional magnetic resonance imaging of the brain and spinal cord during motor sequence learning. Specifically, we show learning-related modulation of activity in the C6–C8 spinal region, which is independent from that of related supraspinal sensorimotor structures. Moreover, a brain–spinal cord functional connectivity analysis demonstrates that the initial linear relationship between the spinal cord and sensorimotor cortex gradually fades away over the course of motor sequence learning, while the connectivity between spinal activity and cerebellum gains strength. These data suggest that the spinal cord not only constitutes an active functional component of the human motor learning network but also contributes distinctively from the brain to the learning process. The present findings open new avenues for rehabilitation of patients with spinal cord injuries, as they demonstrate that this part of the central nervous system is much more plastic than assumed before. Yet, the neurophysiological mechanisms underlying this intrinsic functional plasticity in the spinal cord warrant further investigations. PMID:26125597

Simultaneous Brain-Cervical Cord fMRI Reveals Intrinsic Spinal Cord Plasticity during Motor Sequence Learning.

PubMed

Vahdat, Shahabeddin; Lungu, Ovidiu; Cohen-Adad, Julien; Marchand-Pauvert, Veronique; Benali, Habib; Doyon, Julien

2015-06-01

The spinal cord participates in the execution of skilled movements by translating high-level cerebral motor representations into musculotopic commands. Yet, the extent to which motor skill acquisition relies on intrinsic spinal cord processes remains unknown. To date, attempts to address this question were limited by difficulties in separating spinal local effects from supraspinal influences through traditional electrophysiological and neuroimaging methods. Here, for the first time, we provide evidence for local learning-induced plasticity in intact human spinal cord through simultaneous functional magnetic resonance imaging of the brain and spinal cord during motor sequence learning. Specifically, we show learning-related modulation of activity in the C6-C8 spinal region, which is independent from that of related supraspinal sensorimotor structures. Moreover, a brain-spinal cord functional connectivity analysis demonstrates that the initial linear relationship between the spinal cord and sensorimotor cortex gradually fades away over the course of motor sequence learning, while the connectivity between spinal activity and cerebellum gains strength. These data suggest that the spinal cord not only constitutes an active functional component of the human motor learning network but also contributes distinctively from the brain to the learning process. The present findings open new avenues for rehabilitation of patients with spinal cord injuries, as they demonstrate that this part of the central nervous system is much more plastic than assumed before. Yet, the neurophysiological mechanisms underlying this intrinsic functional plasticity in the spinal cord warrant further investigations.

Threats to intact tropical peatlands and opportunities for their conservation.

PubMed

Roucoux, K H; Lawson, I T; Baker, T R; Del Castillo Torres, D; Draper, F C; Lähteenoja, O; Gilmore, M P; Honorio Coronado, E N; Kelly, T J; Mitchard, E T A; Vriesendorp, C F

2017-12-01

Large, intact areas of tropical peatland are highly threatened at a global scale by the expansion of commercial agriculture and other forms of economic development. Conserving peatlands on a landscape scale, with their hydrology intact, is of international conservation importance to preserve their distinctive biodiversity and ecosystem services and maintain their resilience to future environmental change. We explored threats to and opportunities for conserving remaining intact tropical peatlands; thus, we excluded peatlands of Indonesia and Malaysia, where extensive deforestation, drainage, and conversion to plantations means conservation in this region can protect only small fragments of the original ecosystem. We focused on a case study, the Pastaza-Marañón Foreland Basin (PMFB) in Peru, which is among the largest known intact tropical peatland landscapes in the world and is representative of peatland vulnerability. Maintenance of the hydrological conditions critical for carbon storage and ecosystem function of peatlands is, in the PMFB, primarily threatened by expansion of commercial agriculture linked to new transport infrastructure that is facilitating access to remote areas. There remain opportunities in the PMFB and elsewhere to develop alternative, more sustainable land-use practices. Although some of the peatlands in the PMFB fall within existing legally protected areas, this protection does not include the most carbon-dense (domed pole forest) areas. New carbon-based conservation instruments (e.g., REDD+, Green Climate Fund), developing markets for sustainable peatland products, transferring land title to local communities, and expanding protected areas offer pathways to increased protection for intact tropical peatlands in Amazonia and elsewhere, such as those in New Guinea and Central Africa which remain, for the moment, broadly beyond the frontier of commercial development. © 2017 The Authors. Conservation Biology published by Wiley Periodicals, Inc

Intact emotion recognition and experience but dysfunctional emotion regulation in idiopathic Parkinson's disease.

PubMed

Ille, Rottraut; Wabnegger, Albert; Schwingenschuh, Petra; Katschnig-Winter, Petra; Kögl-Wallner, Mariella; Wenzel, Karoline; Schienle, Anne

2016-02-15

A specific non-motor impairment in Parkinson's disease (PD) concerns difficulties to accurately identify facial emotions. Findings are numerous but very inconsistent, ranging from general discrimination deficits to problems for specific emotions up to no impairment at all. By contrast, only a few studies exist about emotion experience, altered affective traits and states in PD. To investigate the decoding capacity for affective facial expressions, affective experience of emotion-eliciting images and affective personality traits in PD. The study sample included 25 patients with mild to moderate symptom intensity and 25 healthy controls (HC) of both sexes. The participants were shown pictures of facial expressions depicting disgust, fear, and anger as well as disgusting and fear-relevant scenes. Additionally, they answered self-report scales for the assessment of affective traits. PD patients had more problems in controlling anger and disgust feelings than HC. Higher disgust sensitivity in PD was associated with lower functioning in everyday life and lower capacity to recognize angry faces. Furthermore, patients reported less disgust towards poor hygiene and spoiled food and they stated elevated anxiety. However, the clinical group displayed intact facial emotion decoding and emotion experience. Everyday life functionality was lowered in PD and decreased with stronger motor impairment. Furthermore, disease duration was negatively associated to correct classification of angry faces. Our data indicate that problems with emotion regulation may appear already in earlier disease stages of PD. By contrast, PD patients showed appropriate emotion recognition and experience. However, data also point to a deterioration of emotion recognition capacity with the course of the disease. Compensatory mechanisms in PD patients with less advanced disease are discussed. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

HYDROCARBON VAPOR DIFFUSION IN INTACT CORE SLEEVES

EPA Science Inventory

The diffusion of 2,2,4-trimethylpentane (TMP) and 2,2,5-trimethylhexane (TMH) vapors put of residually contaminated sandy soil from the U.S. Environmental Protection Agency (EPA) field research site at Traverse City, Michigan, was measured and modeled. The headspace of an intact ...

Cortical motor activity and reorganization following upper-limb amputation and subsequent targeted reinnervation.

PubMed

Chen, Albert; Yao, Jun; Kuiken, Todd; Dewald, Julius P A

2013-01-01

Previous studies have postulated that the amount of brain reorganization following peripheral injuries may be correlated with negative symptoms or consequences. However, it is unknown whether restoring effective limb function may then be associated with further changes in the expression of this reorganization. Recently, targeted reinnervation (TR), a surgical technique that restores a direct neural connection from amputated sensorimotor nerves to new peripheral targets such as muscle, has been successfully applied to upper-limb amputees. It has been shown to be effective in restoring both peripheral motor and sensory functions via the reinnervated nerves as soon as a few months after the surgery. However, it was unclear whether TR could also restore normal cortical motor representations for control of the missing limb. To answer this question, we used high-density electroencephalography (EEG) to localize cortical activity related to cued motor tasks generated by the intact and missing limb. Using a case study of 3 upper-limb amputees, 2 of whom went through pre and post-TR experiments, we present unique quantitative evidence for the re-mapping of motor representations for the missing limb closer to their original locations following TR. This provides evidence that an effective restoration of peripheral function from TR can be linked to the return of more normal cortical expression for the missing limb. Therefore, cortical mapping may be used as a potential guide for monitoring rehabilitation following peripheral injuries.

Source Selection Simulation: Intact Team Training on Picking a Provider

DTIC Science & Technology

2015-06-01

seat of a new $100 million stealth fighter before giving her flight simulation time. The ar- gument for source-selection simulation ( SSS ) training is...dynamic is the creation of the SSS Tool. Drawing on his success in using a similar tool in contingency contracting, Long decided we should use a Web...of SSS intact team training. On Sept. 30–Oct. 3, 2014, Professors Long and Elsesser de- livered DAU’s first-ever Intact Team SSS Training to Eglin’s

A New Type of Motor: Pneumatic Step Motor

PubMed Central

Stoianovici, Dan; Patriciu, Alexandru; Petrisor, Doru; Mazilu, Dumitru; Kavoussi, Louis

2011-01-01

This paper presents a new type of pneumatic motor, a pneumatic step motor (PneuStep). Directional rotary motion of discrete displacement is achieved by sequentially pressurizing the three ports of the motor. Pulsed pressure waves are generated by a remote pneumatic distributor. The motor assembly includes a motor, gearhead, and incremental position encoder in a compact, central bore construction. A special electronic driver is used to control the new motor with electric stepper indexers and standard motion control cards. The motor accepts open-loop step operation as well as closed-loop control with position feedback from the enclosed sensor. A special control feature is implemented to adapt classic control algorithms to the new motor, and is experimentally validated. The speed performance of the motor degrades with the length of the pneumatic hoses between the distributor and motor. Experimental results are presented to reveal this behavior and set the expectation level. Nevertheless, the stepper achieves easily controllable precise motion unlike other pneumatic motors. The motor was designed to be compatible with magnetic resonance medical imaging equipment, for actuating an image-guided intervention robot, for medical applications. For this reason, the motors were entirely made of nonmagnetic and dielectric materials such as plastics, ceramics, and rubbers. Encoding was performed with fiber optics, so that the motors are electricity free, exclusively using pressure and light. PneuStep is readily applicable to other pneumatic or hydraulic precision-motion applications. PMID:21528106

46 CFR 174.045 - Intact stability requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Intact stability requirements. 174.045 Section 174.045 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units § 174.045...

46 CFR 174.045 - Intact stability requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Intact stability requirements. 174.045 Section 174.045 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units § 174.045...

Visual speech alters the discrimination and identification of non-intact auditory speech in children with hearing loss.

PubMed

Jerger, Susan; Damian, Markus F; McAlpine, Rachel P; Abdi, Hervé

2017-03-01

Understanding spoken language is an audiovisual event that depends critically on the ability to discriminate and identify phonemes yet we have little evidence about the role of early auditory experience and visual speech on the development of these fundamental perceptual skills. Objectives of this research were to determine 1) how visual speech influences phoneme discrimination and identification; 2) whether visual speech influences these two processes in a like manner, such that discrimination predicts identification; and 3) how the degree of hearing loss affects this relationship. Such evidence is crucial for developing effective intervention strategies to mitigate the effects of hearing loss on language development. Participants were 58 children with early-onset sensorineural hearing loss (CHL, 53% girls, M = 9;4 yrs) and 58 children with normal hearing (CNH, 53% girls, M = 9;4 yrs). Test items were consonant-vowel (CV) syllables and nonwords with intact visual speech coupled to non-intact auditory speech (excised onsets) as, for example, an intact consonant/rhyme in the visual track (Baa or Baz) coupled to non-intact onset/rhyme in the auditory track (/-B/aa or/-B/az). The items started with an easy-to-speechread/B/or difficult-to-speechread/G/onset and were presented in the auditory (static face) vs. audiovisual (dynamic face) modes. We assessed discrimination for intact vs. non-intact different pairs (e.g., Baa:/-B/aa). We predicted that visual speech would cause the non-intact onset to be perceived as intact and would therefore generate more same-as opposed to different-responses in the audiovisual than auditory mode. We assessed identification by repetition of nonwords with non-intact onsets (e.g.,/-B/az). We predicted that visual speech would cause the non-intact onset to be perceived as intact and would therefore generate more Baz-as opposed to az- responses in the audiovisual than auditory mode. Performance in the audiovisual mode showed more same

Visual Speech Alters the Discrimination and Identification of Non-Intact Auditory Speech in Children with Hearing Loss

PubMed Central

Jerger, Susan; Damian, Markus F.; McAlpine, Rachel P.; Abdi, Hervé

2017-01-01

Objectives Understanding spoken language is an audiovisual event that depends critically on the ability to discriminate and identify phonemes yet we have little evidence about the role of early auditory experience and visual speech on the development of these fundamental perceptual skills. Objectives of this research were to determine 1) how visual speech influences phoneme discrimination and identification; 2) whether visual speech influences these two processes in a like manner, such that discrimination predicts identification; and 3) how the degree of hearing loss affects this relationship. Such evidence is crucial for developing effective intervention strategies to mitigate the effects of hearing loss on language development. Methods Participants were 58 children with early-onset sensorineural hearing loss (CHL, 53% girls, M = 9;4 yrs) and 58 children with normal hearing (CNH, 53% girls, M = 9;4 yrs). Test items were consonant-vowel (CV) syllables and nonwords with intact visual speech coupled to non-intact auditory speech (excised onsets) as, for example, an intact consonant/rhyme in the visual track (Baa or Baz) coupled to non-intact onset/rhyme in the auditory track (/–B/aa or /–B/az). The items started with an easy-to-speechread /B/ or difficult-to-speechread /G/ onset and were presented in the auditory (static face) vs. audiovisual (dynamic face) modes. We assessed discrimination for intact vs. non-intact different pairs (e.g., Baa:/–B/aa). We predicted that visual speech would cause the non-intact onset to be perceived as intact and would therefore generate more same—as opposed to different—responses in the audiovisual than auditory mode. We assessed identification by repetition of nonwords with non-intact onsets (e.g., /–B/az). We predicted that visual speech would cause the non-intact onset to be perceived as intact and would therefore generate more Baz—as opposed to az— responses in the audiovisual than auditory mode. Results

Quantifying transfer after perceptual-motor sequence learning: how inflexible is implicit learning?

PubMed

Sanchez, Daniel J; Yarnik, Eric N; Reber, Paul J

2015-03-01

Studies of implicit perceptual-motor sequence learning have often shown learning to be inflexibly tied to the training conditions during learning. Since sequence learning is seen as a model task of skill acquisition, limits on the ability to transfer knowledge from the training context to a performance context indicates important constraints on skill learning approaches. Lack of transfer across contexts has been demonstrated by showing that when task elements are changed following training, this leads to a disruption in performance. These results have typically been taken as suggesting that the sequence knowledge relies on integrated representations across task elements (Abrahamse, Jiménez, Verwey, & Clegg, Psychon Bull Rev 17:603-623, 2010a). Using a relatively new sequence learning task, serial interception sequence learning, three experiments are reported that quantify this magnitude of performance disruption after selectively manipulating individual aspects of motor performance or perceptual information. In Experiment 1, selective disruption of the timing or order of sequential actions was examined using a novel response manipulandum that allowed for separate analysis of these two motor response components. In Experiments 2 and 3, transfer was examined after selective disruption of perceptual information that left the motor response sequence intact. All three experiments provided quantifiable estimates of partial transfer to novel contexts that suggest some level of information integration across task elements. However, the ability to identify quantifiable levels of successful transfer indicates that integration is not all-or-none and that measurement sensitivity is a key in understanding sequence knowledge representations.

Quantifying transfer after perceptual-motor sequence learning: how inflexible is implicit learning?

PubMed Central

Sanchez, Daniel J.; Yarnik, Eric N.

2015-01-01

Studies of implicit perceptual-motor sequence learning have often shown learning to be inflexibly tied to the training conditions during learning. Since sequence learning is seen as a model task of skill acquisition, limits on the ability to transfer knowledge from the training context to a performance context indicates important constraints on skill learning approaches. Lack of transfer across contexts has been demonstrated by showing that when task elements are changed following training, this leads to a disruption in performance. These results have typically been taken as suggesting that the sequence knowledge relies on integrated representations across task elements (Abrahamse, Jiménez, Verwey, & Clegg, Psychon Bull Rev 17:603–623, 2010a). Using a relatively new sequence learning task, serial interception sequence learning, three experiments are reported that quantify this magnitude of performance disruption after selectively manipulating individual aspects of motor performance or perceptual information. In Experiment 1, selective disruption of the timing or order of sequential actions was examined using a novel response manipulandum that allowed for separate analysis of these two motor response components. In Experiments 2 and 3, transfer was examined after selective disruption of perceptual information that left the motor response sequence intact. All three experiments provided quantifiable estimates of partial transfer to novel contexts that suggest some level of information integration across task elements. However, the ability to identify quantifiable levels of successful transfer indicates that integration is not all-or-none and that measurement sensitivity is a key in understanding sequence knowledge representations. PMID:24668505

The Multilevel Mixed Intact Group Analysis: A Mixed Method to Seek, Detect, Describe, and Explain Differences Among Intact Groups

ERIC Educational Resources Information Center

Schoonenboom, Judith

2016-01-01

Educational innovations often involve intact subgroups, such as school classes or university departments. In small-scale educational evaluation research, typically involving 1 to 20 subgroups, differences among these subgroups are often neglected. This article presents a mixed method from a qualitative perspective, in which differences among…

Structural determination of intact proteins using mass spectrometry

DOEpatents

Kruppa, Gary [San Francisco, CA; Schoeniger, Joseph S [Oakland, CA; Young, Malin M [Livermore, CA

2008-05-06

The present invention relates to novel methods of determining the sequence and structure of proteins. Specifically, the present invention allows for the analysis of intact proteins within a mass spectrometer. Therefore, preparatory separations need not be performed prior to introducing a protein sample into the mass spectrometer. Also disclosed herein are new instrumental developments for enhancing the signal from the desired modified proteins, methods for producing controlled protein fragments in the mass spectrometer, eliminating complex microseparations, and protein preparatory chemical steps necessary for cross-linking based protein structure determination.Additionally, the preferred method of the present invention involves the determination of protein structures utilizing a top-down analysis of protein structures to search for covalent modifications. In the preferred method, intact proteins are ionized and fragmented within the mass spectrometer.

Pseudomonas aeruginosa infections of intact skin.

PubMed

Agger, W A; Mardan, A

1995-02-01

Pseudomonas aeruginosa infections of healthy skin are uncommon. We report four cases of P. aeruginosa infections of intact skin. These cases illustrate the clinical spectrum of these cutaneous infections: localized, mild epidermal infections (the green nail syndrome and webbed space infections), moderately serious infections (cutaneous folliculitis and otitis externa), and, in immunocompromised patients, extremely serious infections (malignant otitis externa, perirectal infection, and ecthyma gangrenosum).

Fear of movement modulates the feedforward motor control of the affected limb in complex regional pain syndrome (CRPS): A single-case study.

PubMed

Osumi, Michihiro; Sumitani, Masahiko; Otake, Yuko; Morioka, Shu

2018-01-01

Pain-related fear can exacerbate physical disability and pathological pain in complex regional pain syndrome (CRPS) patients. We conducted a kinematic analysis of grasping movements with a pediatric patient suffering from CRPS in an upper limb to investigate how pain-related fear affects motor control. Using a three-dimensional measurement system, we recorded the patient's movement while grasping three vertical bars of different diameters (thin, middle, thick) with the affected and intact hands. We analyzed the maximum grasp distance between the thumb and the index finger (MGD), the peak velocity of the grasp movement (PV), and the time required for the finger opening phase (TOP) and closing phase (TCP). Consequently, the MGD and PV of grasp movements in the affected hand were significantly smaller than those of the intact hand when grasping the middle and thick bars. This might reflect pain-related fear against visual information of the target size which evokes sensation of difficulty in opening fingers widely to grasp the middle and thick bars. Although MGD and PV increased with target size, the TOP was longer in the affected hand when grasping the thick bar. These findings indicate that pain-related fear impairs motor commands that are sent to the musculoskeletal system, subsequently disrupting executed movements and their sensory feedback. Using kinematic analysis, we objectively demonstrated that pain-related fear affects the process of sending motor commands towards the musculoskeletal system in the CRPS-affected hand, providing a possible explanatory model of pathological pain. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development of uncoupling between D1- and D2-mediated motor behavior in rats depleted of dopamine as neonates.

PubMed

Byrnes, E M; Bruno, J P

1994-09-01

The D1- and D2-mediation of stimulated motor behavior was studied in pups (Days 10-11) and weanlings (Days 20-21) that had been depleted of dopamine (DA) on postnatal Day 3. Administration of the D1-like agonist SKF 38393 (30.0 mg/kg) or the D2-like agonist quinpirole (3.0 mg/kg) increased the incidence of sniffing and locomotion in intact and DA-depleted animals tested at either age. However, the ability of selective DA antagonists to reduce these stimulated responses interacted with both the depletion and the age at the time of testing. When tested as pups, both the D1 antagonist SCH 23390 (0.2 or 0.4 mg/kg) and the D2 antagonist clebopride (10.0 mg/kg) suppressed the behaviors induced by either class of DA agonist. When tested as weanlings, intact animals exhibited the profile of pups (i.e., either antagonist blocked each agonist). In DA-depleted weanlings, however, only the D1 antagonist blocked the D1 agonist-induced responses and only the D2 antagonist blocked the D2 agonist-induced responses. These data demonstrate that the interactions between D1 and D2 receptors in the expression of stimulated motor behaviors are altered following DA depletions in neonates. Moreover, this change in receptor function occurs sometime between 7 and 13 days after the DA depletion.

In search of the motor engram: motor map plasticity as a mechanism for encoding motor experience.

PubMed

Monfils, Marie-H; Plautz, Erik J; Kleim, Jeffrey A

2005-10-01

Motor skill acquisition occurs through modification and organization of muscle synergies into effective movement sequences. The learning process is reflected neurophysiologically as a reorganization of movement representations within the primary motor cortex, suggesting that the motor map is a motor engram. However, the specific neural mechanisms underlying map plasticity are unknown. Here the authors review evidence that 1) motor map topography reflects the capacity for skilled movement, 2) motor skill learning induces reorganization of motor maps in a manner that reflects the kinematics of acquired skilled movement, 3) map plasticity is supported by a reorganization of cortical microcircuitry involving changes in synaptic efficacy, and 4) motor map integrity and topography are influenced by various neurochemical signals that coordinate changes in cortical circuitry to encode motor experience. Finally, the role of motor map plasticity in recovery of motor function after brain damage is discussed.

How can we conserve intact tropical peatlands?

NASA Astrophysics Data System (ADS)

Lawson, Ian; Roucoux, Katherine

2017-04-01

The scientific community has, for more than three decades, been expressing increasing alarm about the fate of peatlands in parts of Indonesia and Malaysia, where extensive land-use conversion and drainage for rice and oil palm have greatly compromised peatland hydrology, ecology, biological richness, and carbon storage. The discourse in the literature on these peatlands is now moving on from attempts to preserve the last remaining fragments of peat-swamp forest, towards discussion of how best to restore damaged ecosystems, and whether it is possible to manage plantations more 'sustainably'. It is becoming increasingly clear, however, that peatlands occur quite widely in other parts of the lowland tropics, including parts of Amazonia and the Congo Basin, and many of these peatlands can reasonably be described as 'intact': although few if any parts of the tropics are totally unaffected by human actions, the hydrology and functional ecology of these systems appear to be close to a 'natural' state. The question then arises as to what should be done with the knowledge of their existence. Here we analyse the arguments in favour of protecting intact peatlands, and the potential conflicts with other priorities such as economic development and social justice. We evaluate alternative mechanisms for protecting intact peatlands, focusing on the particular issues raised by peatlands as opposed to other kinds of tropical ecosystem. We identify ways in which natural science agendas can help to inform these arguments, using our own contributions in palaeoecology and carbon mapping as examples. Finally, we argue for a radical reconsideration of research agendas in tropical peatlands, highlighting the potential contribution of methodologies borrowed from the social sciences and humanities.

Calcium Signaling in Intact Dorsal Root Ganglia

PubMed Central

Gemes, Geza; Rigaud, Marcel; Koopmeiners, Andrew S.; Poroli, Mark J.; Zoga, Vasiliki; Hogan, Quinn H.

2013-01-01

Background Ca2+ is the dominant second messenger in primary sensory neurons. In addition, disrupted Ca2+ signaling is a prominent feature in pain models involving peripheral nerve injury. Standard cytoplasmic Ca2+ recording techniques use high K+ or field stimulation and dissociated neurons. To compare findings in intact dorsal root ganglia, we used a method of simultaneous electrophysiologic and microfluorimetric recording. Methods Dissociated neurons were loaded by bath-applied Fura-2-AM and subjected to field stimulation. Alternatively, we adapted a technique in which neuronal somata of intact ganglia were loaded with Fura-2 through an intracellular microelectrode that provided simultaneous membrane potential recording during activation by action potentials (APs) conducted from attached dorsal roots. Results Field stimulation at levels necessary to activate neurons generated bath pH changes through electrolysis and failed to predictably drive neurons with AP trains. In the intact ganglion technique, single APs produced measurable Ca2+ transients that were fourfold larger in presumed nociceptive C-type neurons than in nonnociceptive Aβ-type neurons. Unitary Ca2+ transients summated during AP trains, forming transients with amplitudes that were highly dependent on stimulation frequency. Each neuron was tuned to a preferred frequency at which transient amplitude was maximal. Transients predominantly exhibited monoexponential recovery and had sustained plateaus during recovery only with trains of more than 100 APs. Nerve injury decreased Ca2+ transients in C-type neurons, but increased transients in Aβ-type neurons. Conclusions Refined observation of Ca2+ signaling is possible through natural activation by conducted APs in undissociated sensory neurons and reveals features distinct to neuronal types and injury state. PMID:20526180

Losing a jewel-Rapid declines in Myanmar's intact forests from 2002-2014.

PubMed

Bhagwat, Tejas; Hess, Andrea; Horning, Ned; Khaing, Thiri; Thein, Zaw Min; Aung, Kyaw Moe; Aung, Kyaw Htet; Phyo, Paing; Tun, Ye Lin; Oo, Aung Htat; Neil, Anthony; Thu, Win Myo; Songer, Melissa; LaJeunesse Connette, Katherine; Bernd, Asja; Huang, Qiongyu; Connette, Grant; Leimgruber, Peter

2017-01-01

New and rapid political and economic changes in Myanmar are increasing the pressures on the country's forests. Yet, little is known about the past and current condition of these forests and how fast they are declining. We mapped forest cover in Myanmar through a consortium of international organizations and environmental non-governmental groups, using freely-available public domain data and open source software tools. We used Landsat satellite imagery to assess the condition and spatial distribution of Myanmar's intact and degraded forests with special focus on changes in intact forest between 2002 and 2014. We found that forests cover 42,365,729 ha or 63% of Myanmar, making it one of the most forested countries in the region. However, severe logging, expanding plantations, and degradation pose increasing threats. Only 38% of the country's forests can be considered intact with canopy cover >80%. Between 2002 and 2014, intact forests declined at a rate of 0.94% annually, totaling more than 2 million ha forest loss. Losses can be extremely high locally and we identified 9 townships as forest conversion hotspots. We also delineated 13 large (>100,000 ha) and contiguous intact forest landscapes, which are dispersed across Myanmar. The Northern Forest Complex supports four of these landscapes, totaling over 6.1 million ha of intact forest, followed by the Southern Forest Complex with three landscapes, comprising 1.5 million ha. These remaining contiguous forest landscape should have high priority for protection. Our project demonstrates how open source data and software can be used to develop and share critical information on forests when such data are not readily available elsewhere. We provide all data, code, and outputs freely via the internet at (for scripts: https://bitbucket.org/rsbiodiv/; for the data: http://geonode.themimu.info/layers/geonode%3Amyan_lvl2_smoothed_dec2015_resamp).

Quantitative bioluminescence imaging of transgene expression in intact porcine antral follicles in vitro.

PubMed

Jung, Song-yi; Willard, Scott T

2014-01-30

The porcine oocyte maturation in vivo occurs within the ovarian follicle and is regulated by the interactions between oocytes and surrounding follicular components, including theca, granulosa, and cumulus cells, and follicular fluid. Therefore, the antral follicle is an essential microenvironment for efficient oocyte maturation and its developmental competence. Quantitative bioluminescence imaging of firefly luciferase reporter genes in an intact antral follicle would allow investigation of changes in cellular and molecular events and in the context of the whole follicles. In this study, we investigate factors influencing bioluminescence measurements as a first step towards developing a new bioluminescence imaging system for intact antral follicles. We analyzed the time course of bioluminescence emitted from transfected living intact follicles using a cationic lipid mediated gene transfer method with increasing doses (1-3 μg) of firefly luciferase reporter gene (pGL4). In addition, a standard luciferase assay was used to confirm the luciferase expression in granulosa cells in the transfected intact antral follicles. Finally, the dose effects of substrate, D-luciferin, were determined for optimal quantitative bioluminescence imaging of intact porcine antral follicles in vitro. The level of luciferase activity of follicles with 3 μg pGL4 was significantly (P < 0.05) greater than the 1 μg and 2 μg groups at 1 min after D-luciferin injection. The bioluminescence intensity of transfected follicles reached a peak at 1 min, and then it was significantly (P < 0.05) reduced within 2 min after injection of D-luciferin; with the level of bioluminescence emission remained constant from 2.5 to 10 min. The bioluminescence emission was maximal with 300 μg of D-luciferin. The results of this study suggested that the investigation of factors influencing bioluminescence measurements is a critical step toward developing a new bioluminescence imaging model. This

Quantitative bioluminescence imaging of transgene expression in intact porcine antral follicles in vitro

PubMed Central

2014-01-01

Background The porcine oocyte maturation in vivo occurs within the ovarian follicle and is regulated by the interactions between oocytes and surrounding follicular components, including theca, granulosa, and cumulus cells, and follicular fluid. Therefore, the antral follicle is an essential microenvironment for efficient oocyte maturation and its developmental competence. Quantitative bioluminescence imaging of firefly luciferase reporter genes in an intact antral follicle would allow investigation of changes in cellular and molecular events and in the context of the whole follicles. In this study, we investigate factors influencing bioluminescence measurements as a first step towards developing a new bioluminescence imaging system for intact antral follicles. Methods We analyzed the time course of bioluminescence emitted from transfected living intact follicles using a cationic lipid mediated gene transfer method with increasing doses (1-3 μg) of firefly luciferase reporter gene (pGL4). In addition, a standard luciferase assay was used to confirm the luciferase expression in granulosa cells in the transfected intact antral follicles. Finally, the dose effects of substrate, D-luciferin, were determined for optimal quantitative bioluminescence imaging of intact porcine antral follicles in vitro. Results The level of luciferase activity of follicles with 3 μg pGL4 was significantly (P < 0.05) greater than the 1 μg and 2 μg groups at 1 min after D-luciferin injection. The bioluminescence intensity of transfected follicles reached a peak at 1 min, and then it was significantly (P < 0.05) reduced within 2 min after injection of D-luciferin; with the level of bioluminescence emission remained constant from 2.5 to 10 min. The bioluminescence emission was maximal with 300 μg of D-luciferin. Conclusions The results of this study suggested that the investigation of factors influencing bioluminescence measurements is a critical step toward developing a

Abnormal functional connectivity and cortical integrity influence dominant hand motor disability in multiple sclerosis: a multimodal analysis.

PubMed

Zhong, Jidan; Nantes, Julia C; Holmes, Scott A; Gallant, Serge; Narayanan, Sridar; Koski, Lisa

2016-12-01

Functional reorganization and structural damage occur in the brains of people with multiple sclerosis (MS) throughout the disease course. However, the relationship between resting-state functional connectivity (FC) reorganization in the sensorimotor network and motor disability in MS is not well understood. This study used resting-state fMRI, T1-weighted and T2-weighted, and magnetization transfer (MT) imaging to investigate the relationship between abnormal FC in the sensorimotor network and upper limb motor disability in people with MS, as well as the impact of disease-related structural abnormalities within this network. Specifically, the differences in FC of the left hemisphere hand motor region between MS participants with preserved (n = 17) and impaired (n = 26) right hand function, compared with healthy controls (n = 20) was investigated. Differences in brain atrophy and MT ratio measured at the global and regional levels were also investigated between the three groups. Motor preserved MS participants had stronger FC in structurally intact visual information processing regions relative to motor impaired MS participants. Motor impaired MS participants showed weaker FC in the sensorimotor and somatosensory association cortices and more severe structural damage throughout the brain compared with the other groups. Logistic regression analysis showed that regional MTR predicted motor disability beyond the impact of global atrophy whereas regional grey matter volume did not. More importantly, as the first multimodal analysis combining resting-state fMRI, T1-weighted, T2-weighted and MTR images in MS, we demonstrate how a combination of structural and functional changes may contribute to motor impairment or preservation in MS. Hum Brain Mapp 37:4262-4275, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Cerebral-buccal pathways in Aplysia californica: synaptic connections, cooperative interneuronal effects and feedback during buccal motor programs.

PubMed

Sánchez, J A; Kirk, M D

2001-12-01

Ingestion of seaweed by Aplysia is in part mediated by cerebral-buccal interneurons that drive rhythmic motor output from the buccal ganglia and in some cases cerebral-buccal interneurons act as members of the feeding central pattern generator. Here we document cooperative interactions between cerebral-buccal interneuron 2 and cerebral-buccal interneuron 12, characterize synaptic input to cerebral-buccal interneuron 2 and cerebral-buccal interneuron 12 from buccal peripheral nerve 2,3, describe a synaptic connection between cerebral-buccal interneuron 1 and buccal neuron B34, further characterize connections made by cerebral-buccal interneurons 2 and -12 with B34 and B61/62, and describe a novel, inhibitory connection made by cerebral-buccal interneuron 2 with a buccal neuron. When cerebral-buccal interneurons 2 and 12 were driven synchronously at low frequencies, ingestion-like buccal motor programs were elicited, and if either was driven alone, indirect synaptic input was recruited in the other cerebral-buccal interneuron. Stimulation of BN2,3 recruited both ingestion and rejection-like motor programs without firing in cerebral-buccal interneurons 2 or 12. During motor programs elicited by cerebral-buccal interneurons 2 or 12, high-voltage stimulation of BN2,3 inhibited firing in both cerebral-buccal interneurons. Our results suggest that cerebral-buccal interneurons 2 and 12 use cooperative interactions to modulate buccal motor programs, yet firing in cerebral-buccal interneurons 2 or 12 is not necessary for recruiting motor programs by buccal peripheral nerve BN2,3, even in preparations with intact cerebral-buccal pathways.

Learning fast accurate movements requires intact frontostriatal circuits

PubMed Central

Shabbott, Britne; Ravindran, Roshni; Schumacher, Joseph W.; Wasserman, Paula B.; Marder, Karen S.; Mazzoni, Pietro

2013-01-01

The basal ganglia are known to play a crucial role in movement execution, but their importance for motor skill learning remains unclear. Obstacles to our understanding include the lack of a universally accepted definition of motor skill learning (definition confound), and difficulties in distinguishing learning deficits from execution impairments (performance confound). We studied how healthy subjects and subjects with a basal ganglia disorder learn fast accurate reaching movements. We addressed the definition and performance confounds by: (1) focusing on an operationally defined core element of motor skill learning (speed-accuracy learning), and (2) using normal variation in initial performance to separate movement execution impairment from motor learning abnormalities. We measured motor skill learning as performance improvement in a reaching task with a speed-accuracy trade-off. We compared the performance of subjects with Huntington's disease (HD), a neurodegenerative basal ganglia disorder, to that of premanifest carriers of the HD mutation and of control subjects. The initial movements of HD subjects were less skilled (slower and/or less accurate) than those of control subjects. To factor out these differences in initial execution, we modeled the relationship between learning and baseline performance in control subjects. Subjects with HD exhibited a clear learning impairment that was not explained by differences in initial performance. These results support a role for the basal ganglia in both movement execution and motor skill learning. PMID:24312037

An experimental study of the putative mechanism of a synthetic autonomous rotary DNA nanomotor

NASA Astrophysics Data System (ADS)

Dunn, K. E.; Leake, M. C.; Wollman, A. J. M.; Trefzer, M. A.; Johnson, S.; Tyrrell, A. M.

2017-03-01

DNA has been used to construct a wide variety of nanoscale molecular devices. Inspiration for such synthetic molecular machines is frequently drawn from protein motors, which are naturally occurring and ubiquitous. However, despite the fact that rotary motors such as ATP synthase and the bacterial flagellar motor play extremely important roles in nature, very few rotary devices have been constructed using DNA. This paper describes an experimental study of the putative mechanism of a rotary DNA nanomotor, which is based on strand displacement, the phenomenon that powers many synthetic linear DNA motors. Unlike other examples of rotary DNA machines, the device described here is designed to be capable of autonomous operation after it is triggered. The experimental results are consistent with operation of the motor as expected, and future work on an enhanced motor design may allow rotation to be observed at the single-molecule level. The rotary motor concept presented here has potential applications in molecular processing, DNA computing, biosensing and photonics.

Dissipation of the Proton Electrochemical Potential in Intact and Lysed Chloroplasts 1

PubMed Central

Nishio, John N.; Whitmarsh, John

1991-01-01

Effective ionophore:chlorophyll ratios were determined for various ionophores that decrease the electrical potential across thylakoid membranes in intact and hypo-osmotically lysed chloroplasts isolated from spinach (Spinacia oleracea). The efficacy of gramicidin D, valinomycin, carbonylcyanide m-chlorophenylhydrazone, and dicyclohexano-18-crown-6 in collapsing the electrical potential was determined spectrophotometrically by the decay half-time of the absorbance change at 518 nanometers induced by a saturating, single turnover flash. The results show that the effectiveness of the ionophores in collapsing the electrical potential in intact and lysed chloroplasts depends on the amount of ionophore-accessible membrane in the assay medium. Only gramicidin exhibited a significant difference in efficacy between intact and lysed chloroplasts. The ratio of gramicidin to chlorophyll required to collapse the electrical potential was more than 50 times higher in intact chloroplasts than in lysed chloroplasts. The efficacy of carbonylcyanide m-chlorophenylhydrazone was significantly reduced in the presence of bovine serum albumin. The other ionophores tested maintained their potency in the presence of bovine serum albumin. Valinomycin was the most effective ionophore tested for collapsing the electrical potential in intact chloroplasts, whereas gramicidin was the most potent ionophore in lysed chloroplasts. The significance of the ionophore:chlorophyll ratios required to collapse the electrical potential is discussed with regard to bioenergetic studies, especially those that examine the contribution of the transmembrane electrochemical potential to protein transport into chloroplasts. PMID:16668015

Childrearing Fathers in Intact Families With Preschoolers.

ERIC Educational Resources Information Center

Radin, Norma

Few empirical studies have specifically examined antecedents and consequences of reversing childrearing roles. A sample of 59 white, intact, middle-class families with a preschool-aged child, 32 with boys and 27 with girls, was studied. Also explored were the father's sex-role orientation and selected paternal behaviors and attitudes. It was found…

Multi-Axis Prosthetic Knee Resembles Alpine Skiing Movements of an Intact Leg

PubMed Central

Demšar, Ivan; Duhovnik, Jože; Lešnik, Blaž; Supej, Matej

2015-01-01

The purpose of the study was to analyse the flexion angles of the ski boot, ankle and knee joints of an above-knee prosthesis and to compare them with an intact leg and a control group of skiers. One subject with an above-knee amputation of the right leg and eight healthy subjects simulated the movement of a skiing turn by performing two-leg squats in laboratory conditions. By adding additional loads in proportion to body weight (BW; +1/3 BW, +2/3 BW, +3/3 BW), various skiing regimes were simulated. Change of Flexion Angle (CoFA) and Range of Motion (RoM) in the ski boot, ankle and knee joints were calculated and compared. An average RoM in the skiing boot on the side of prosthesis (4.4 ± 1.1°) was significantly lower compared to an intact leg (5.9 ± 1.8°) and the control group (6.5 ± 2.3°). In the ankle joint, the average RoM was determined to be 13.2±2.9° in the prosthesis, 12.7 ± 2.8° in an intact leg and 14.8±3.6 in the control group. However, the RoM of the knee joint in the prosthesis (42.2 ± 4.2°) was significantly larger than that of the intact leg (34.7 ± 4.4°). The average RoM of the knee joint in the control group was 47.8 ± 5.4°. The influences of additional loads on the kinematics of the lower extremities were different on the side of the prosthesis and on the intact leg. In contrast, additional loads did not produce any significant differences in the control group. Although different CoFAs in the ski boot, ankle and knee joints were used, an above-knee prosthesis with a built-in multi-axis prosthetic knee enables comparable leg kinematics in simulated alpine skiing. Key points The RoM in the ski boot on the side of the prosthetic leg was smaller than the RoM of the intact leg and the control group of healthy subjects. The RoM in the ankle joint of prosthetic leg was comparable to that of the intact leg and the control group of healthy subjects. The RoM in the prosthetic knee joint was greater than the RoM in the knee joint of the

Vehicle influence on permeation through intact and compromised skin.

PubMed

Gujjar, Meera; Banga, Ajay K

2014-09-10

The purpose of this study was to compare the transdermal permeation of a model compound, diclofenac diethylamine, from a hydrophilic and lipophilic vehicle across in vitro models simulating compromised skin. Mineral oil served as a lipophilic vehicle while 10mM phosphate buffered saline served as a hydrophilic vehicle. Compromised skin was simulated by tape stripping, delipidization, or microneedle application and compared with intact skin as a control. Transepidermal water loss was measured to assess barrier function. Skin compromised with tape stripping and delipidization significantly (p<0.05) increased permeation of diclofenac diethylamine compared to intact and microneedle treated skin with phosphate buffered saline vehicle. A similar trend in permeation was observed with mineral oil as the vehicle. For both vehicles, permeation across skin increased in the same order and correlated with degree of barrier impairment as indicated by transepidermal water loss values: intact

Antimicrobial activity of a new intact skin antisepsis formulation.

PubMed

Russo, Antonello; Viotti, Pier Luigi; Vitali, Matteo; Clementi, Massimo

2003-04-01

Different antiseptic formulations have shown limitations when applied to disinfecting intact skin, notably short-term tolerability and/or efficacy. The purpose of this study was optimizing a new antiseptic formulation specifically targeted at intact skin disinfection and evaluating its in vitro microbicidal activity and in vivo efficacy. The biocidal properties of the antiseptic solution containing 0.5% chloramine-T diluted in 50% isopropyl alcohol (Cloral; Eurospital SpA Trieste, Italy) were measured in vitro versus gram-positive-, gram-negative-, and acid-alcohol-resistant germs and fungi with standard suspension tests in the presence of fetal bovine serum. Virus-inhibiting activity was evaluated in vitro against human cytomegalovirus, herpes simplex virus, poliovirus, hepatitis B virus, and hepatitis C virus. Tests used different methods for the different biologic and in vitro replication capacity of these human viruses. Lastly, Cloral tolerability and skin colonization retardation efficacy after disinfection were studied in vivo. The antiseptic under review showed fast and sustained antimicrobial activity. The efficacy of Cloral against clinically important bacterial and viral pathogens and fungi was highlighted under the experimental conditions described in this article. Finally, microbial regrowth lag and no side effects were documented in vivo after disinfection of 11 volunteers. A stable chloramine-T solution in isopropyl alcohol may be suggested for intact skin antisepsis.

Investigation of Mitochondrial Dysfunction by Sequential Microplate-Based Respiration Measurements from Intact and Permeabilized Neurons

PubMed Central

Clerc, Pascaline; Polster, Brian M.

2012-01-01

Mitochondrial dysfunction is a component of many neurodegenerative conditions. Measurement of oxygen consumption from intact neurons enables evaluation of mitochondrial bioenergetics under conditions that are more physiologically realistic compared to isolated mitochondria. However, mechanistic analysis of mitochondrial function in cells is complicated by changing energy demands and lack of substrate control. Here we describe a technique for sequentially measuring respiration from intact and saponin-permeabilized cortical neurons on single microplates. This technique allows control of substrates to individual electron transport chain complexes following permeabilization, as well as side-by-side comparisons to intact cells. To illustrate the utility of the technique, we demonstrate that inhibition of respiration by the drug KB-R7943 in intact neurons is relieved by delivery of the complex II substrate succinate, but not by complex I substrates, via acute saponin permeabilization. In contrast, methyl succinate, a putative cell permeable complex II substrate, failed to rescue respiration in intact neurons and was a poor complex II substrate in permeabilized cells. Sequential measurements of intact and permeabilized cell respiration should be particularly useful for evaluating indirect mitochondrial toxicity due to drugs or cellular signaling events which cannot be readily studied using isolated mitochondria. PMID:22496810

Zika virus-induced acute myelitis and motor deficits in adult interferon αβ/γ receptor knockout mice.

PubMed

Zukor, Katherine; Wang, Hong; Siddharthan, Venkatraman; Julander, Justin G; Morrey, John D

2018-06-01

Zika virus (ZIKV) has received widespread attention because of its effect on the developing fetus. It is becoming apparent, however, that severe neurological sequelae, such as Guillian-Barrë syndrome (GBS), myelitis, encephalitis, and seizures can occur after infection of adults. This study demonstrates that a contemporary strain of ZIKV can widely infect astrocytes and neurons in the brain and spinal cord of adult, interferon α/β receptor knockout mice (AG129 strain) and cause progressive hindlimb paralysis, as well as severe seizure-like activity during the acute phase of disease. The severity of hindlimb motor deficits correlated with increased numbers of ZIKV-infected lumbosacral spinal motor neurons and decreased numbers of spinal motor neurons. Electrophysiological compound muscle action potential (CMAP) amplitudes in response to stimulation of the lumbosacral spinal cord were reduced when obvious motor deficits were present. ZIKV immunoreactivity was high, intense, and obvious in tissue sections of the brain and spinal cord. Infection in the brain and spinal cord was also associated with astrogliosis as well as T cell and neutrophil infiltration. CMAP and histological analysis indicated that peripheral nerve and muscle functions were intact. Consequently, motor deficits in these circumstances appear to be primarily due to myelitis and possibly encephalitis as opposed to a peripheral neuropathy or a GBS-like syndrome. Thus, acute ZIKV infection of adult AG129 mice may be a useful model for ZIKV-induced myelitis, encephalitis, and seizure activity.

Comparison of Ripening Processes in Intact Tomato Fruit and Excised Pericarp Discs 1

PubMed Central

Campbell, Alan D.; Huysamer, Marius; Stotz, Henrik U.; Greve, L. Carl; Labavitch, John M.

1990-01-01

Physiological processes characteristic of ripening in tissues of intact tomato fruit (Lycopersicon esculentum Mill.) were examined in excised pericarp discs. Pericarp discs were prepared from mature-green tomato fruit and stored in 24-well culture plates, in which individual discs could be monitored for color change, ethylene biosynthesis, and respiration, and selected for cell wall analysis. Within the context of these preparation and handling procedures, most whole fruit ripening processes were maintained in pericarp discs. Pericarp discs and matched intact fruit passed through the same skin color stages at similar rates, as expressed in the L*a*b* color space, changing from green (a* < −5) to red (a* > 15) in about 6 days. Individual tissues of the pericarp discs changed color in the same sequence seen in intact fruit (exocarp, endocarp, then vascular parenchyma). Discs from different areas changed in the same spatial sequence seen in intact fruit (bottom, middle, top). Pericarp discs exhibited climacteric increases in ethylene biosynthesis and CO2 production comparable with those seen in intact fruit, but these were more tightly linked to rate of color change, reaching a peak around a* = 5. Tomato pericarp discs decreased in firmness as color changed. Cell wall carbohydrate composition changed with color as in intact fruit: the quantity of water-soluble pectin eluted from the starch-free alcohol insoluble substances steadily increased and more tightly bound, water-insoluble, pectin decreased in inverse relationship. The cell wall content of the neutral sugars arabinose, rhamnose, and galactose steadily decreased as color changed. The extractable activity of specific cell wall hydrolases changed as in intact fruit: polygalacturonase activity, not detectable in green discs (a* = −5), appeared as discs turned yellow-red (a* = 5), and increased another eight-fold as discs became full red (a* value +20). Carboxymethyl-cellulase activity, low in extracts from

Independent evolution of neurotoxin and flagellar genetic loci in proteolytic Clostridium botulinum

PubMed Central

Carter, Andrew T; Paul, Catherine J; Mason, David R; Twine, Susan M; Alston, Mark J; Logan, Susan M; Austin, John W; Peck, Michael W

2009-01-01

Background Proteolytic Clostridium botulinum is the causative agent of botulism, a severe neuroparalytic illness. Given the severity of botulism, surprisingly little is known of the population structure, biology, phylogeny or evolution of C. botulinum. The recent determination of the genome sequence of C. botulinum has allowed comparative genomic indexing using a DNA microarray. Results Whole genome microarray analysis revealed that 63% of the coding sequences (CDSs) present in reference strain ATCC 3502 were common to all 61 widely-representative strains of proteolytic C. botulinum and the closely related C. sporogenes tested. This indicates a relatively stable genome. There was, however, evidence for recombination and genetic exchange, in particular within the neurotoxin gene and cluster (including transfer of neurotoxin genes to C. sporogenes), and the flagellar glycosylation island (FGI). These two loci appear to have evolved independently from each other, and from the remainder of the genetic complement. A number of strains were atypical; for example, while 10 out of 14 strains that formed type A1 toxin gave almost identical profiles in whole genome, neurotoxin cluster and FGI analyses, the other four strains showed divergent properties. Furthermore, a new neurotoxin sub-type (A5) has been discovered in strains from heroin-associated wound botulism cases. For the first time, differences in glycosylation profiles of the flagella could be linked to differences in the gene content of the FGI. Conclusion Proteolytic C. botulinum has a stable genome backbone containing specific regions of genetic heterogeneity. These include the neurotoxin gene cluster and the FGI, each having evolved independently of each other and the remainder of the genetic complement. Analysis of these genetic components provides a high degree of discrimination of strains of proteolytic C. botulinum, and is suitable for clinical and forensic investigations of botulism outbreaks. PMID:19298644

Independent evolution of neurotoxin and flagellar genetic loci in proteolytic Clostridium botulinum.

PubMed

Carter, Andrew T; Paul, Catherine J; Mason, David R; Twine, Susan M; Alston, Mark J; Logan, Susan M; Austin, John W; Peck, Michael W

2009-03-19

Proteolytic Clostridium botulinum is the causative agent of botulism, a severe neuroparalytic illness. Given the severity of botulism, surprisingly little is known of the population structure, biology, phylogeny or evolution of C. botulinum. The recent determination of the genome sequence of C. botulinum has allowed comparative genomic indexing using a DNA microarray. Whole genome microarray analysis revealed that 63% of the coding sequences (CDSs) present in reference strain ATCC 3502 were common to all 61 widely-representative strains of proteolytic C. botulinum and the closely related C. sporogenes tested. This indicates a relatively stable genome. There was, however, evidence for recombination and genetic exchange, in particular within the neurotoxin gene and cluster (including transfer of neurotoxin genes to C. sporogenes), and the flagellar glycosylation island (FGI). These two loci appear to have evolved independently from each other, and from the remainder of the genetic complement. A number of strains were atypical; for example, while 10 out of 14 strains that formed type A1 toxin gave almost identical profiles in whole genome, neurotoxin cluster and FGI analyses, the other four strains showed divergent properties. Furthermore, a new neurotoxin sub-type (A5) has been discovered in strains from heroin-associated wound botulism cases. For the first time, differences in glycosylation profiles of the flagella could be linked to differences in the gene content of the FGI. Proteolytic C. botulinum has a stable genome backbone containing specific regions of genetic heterogeneity. These include the neurotoxin gene cluster and the FGI, each having evolved independently of each other and the remainder of the genetic complement. Analysis of these genetic components provides a high degree of discrimination of strains of proteolytic C. botulinum, and is suitable for clinical and forensic investigations of botulism outbreaks.

Entropy and information in flagellar axoneme cybernetics: a radial spokes integrative function.

PubMed

Cibert, Christian

2003-04-01

Radial spokes and the consequences of their relationships with the central apparatus seem to play a very important role in the regulation of axonemal activity. We modeled their behavior and observed that it appears to differ in the cilium and the flagellum with respect to the development of bending as a function of time. Specifically, our calculation raises the question of the real function of the radial spokes in the regulation of the axoneme, because a given curvature of the flagellar axoneme may correspond to two opposite of their tilts. The stable nil/low amplitude shear points that we had characterized along the flagellum allowed us to describe their axoneme as a series of modules [Cibert, 2002: Cell Motil. Cytoskeleton 51:89-111]. We observed that a nil/low shearing point moves along each module during beating when a new bend is created at the base of the flagellum [Cibert, 2001: Cell Motil. Cytoskeleton 49:161-175]. We propose that the structural gradients of isoforms of tubulin could be basic verniers that act as structural references for the axonemal machinery during the beating. This allowed us to interpret the axonemal organization as a segmented structure, that could be analyzed according to the complexion(1) theory and Shannon's information theory, which associate entropy and probability in the creation of information. The important consequence of this interpretation is that regulation of the axonemal machinery appears to be due to the upstream and downstream cross-talk between the axonemal segments that do not involve any dedicated integrative structure but depend on the energy level of the entire length of each module. Copyright 2003 Wiley-Liss, Inc.(1)Complexion was defined by Boltzman in 1877 and used by Planck in 1900 to calculate the energy distribution of a normal spectrum [Morowitz, 1970].

Differential activation of an identified motor neuron and neuromodulation provide Aplysia's retractor muscle an additional function.

PubMed

McManus, Jeffrey M; Lu, Hui; Cullins, Miranda J; Chiel, Hillel J

2014-08-15

To survive, animals must use the same peripheral structures to perform a variety of tasks. How does a nervous system employ one muscle to perform multiple functions? We addressed this question through work on the I3 jaw muscle of the marine mollusk Aplysia californica's feeding system. This muscle mediates retraction of Aplysia's food grasper in multiple feeding responses and is innervated by a pool of identified neurons that activate different muscle regions. One I3 motor neuron, B38, is active in the protraction phase, rather than the retraction phase, suggesting the muscle has an additional function. We used intracellular, extracellular, and muscle force recordings in several in vitro preparations as well as recordings of nerve and muscle activity from intact, behaving animals to characterize B38's activation of the muscle and its activity in different behavior types. We show that B38 specifically activates the anterior region of I3 and is specifically recruited during one behavior, swallowing. The function of this protraction-phase jaw muscle contraction is to hold food; thus the I3 muscle has an additional function beyond mediating retraction. We additionally show that B38's typical activity during in vivo swallowing is insufficient to generate force in an unmodulated muscle and that intrinsic and extrinsic modulation shift the force-frequency relationship to allow contraction. Using methods that traverse levels from individual neuron to muscle to intact animal, we show how regional muscle activation, differential motor neuron recruitment, and neuromodulation are key components in Aplysia's generation of multifunctionality. Copyright © 2014 the American Physiological Society.

To What Extent Can Motor Imagery Replace Motor Execution While Learning a Fine Motor Skill?

PubMed Central

Sobierajewicz, Jagna; Szarkiewicz, Sylwia; Przekoracka-Krawczyk, Anna; Jaśkowski, Wojciech; van der Lubbe, Rob

2016-01-01

Motor imagery is generally thought to share common mechanisms with motor execution. In the present study, we examined to what extent learning a fine motor skill by motor imagery may substitute physical practice. Learning effects were assessed by manipulating the proportion of motor execution and motor imagery trials. Additionally, learning effects were compared between participants with an explicit motor imagery instruction and a control group. A Go/NoGo discrete sequence production (DSP) task was employed, wherein a five-stimulus sequence presented on each trial indicated the required sequence of finger movements after a Go signal. In the case of a NoGo signal, participants either had to imagine carrying out the response sequence (the motor imagery group), or the response sequence had to be withheld (the control group). Two practice days were followed by a final test day on which all sequences had to be executed. Learning effects were assessed by computing response times (RTs) and the percentages of correct responses (PCs). The electroencephalogram (EEG ) was additionally measured on this test day to examine whether motor preparation and the involvement of visual short term memory (VST M) depended on the amount of physical/mental practice. Accuracy data indicated strong learning effects. However, a substantial amount of physical practice was required to reach an optimal speed. EEG results suggest the involvement of VST M for sequences that had less or no physical practice in both groups. The absence of differences between the motor imagery and the control group underlines the possibility that motor preparation may actually resemble motor imagery. PMID:28154614

To What Extent Can Motor Imagery Replace Motor Execution While Learning a Fine Motor Skill?

PubMed

Sobierajewicz, Jagna; Szarkiewicz, Sylwia; Przekoracka-Krawczyk, Anna; Jaśkowski, Wojciech; van der Lubbe, Rob

2016-01-01

Motor imagery is generally thought to share common mechanisms with motor execution. In the present study, we examined to what extent learning a fine motor skill by motor imagery may substitute physical practice. Learning effects were assessed by manipulating the proportion of motor execution and motor imagery trials. Additionally, learning effects were compared between participants with an explicit motor imagery instruction and a control group. A Go/NoGo discrete sequence production (DSP) task was employed, wherein a five-stimulus sequence presented on each trial indicated the required sequence of finger movements after a Go signal. In the case of a NoGo signal, participants either had to imagine carrying out the response sequence (the motor imagery group), or the response sequence had to be withheld (the control group). Two practice days were followed by a final test day on which all sequences had to be executed. Learning effects were assessed by computing response times (RTs) and the percentages of correct responses (PCs). The electroencephalogram (EEG ) was additionally measured on this test day to examine whether motor preparation and the involvement of visual short term memory (VST M) depended on the amount of physical/mental practice. Accuracy data indicated strong learning effects. However, a substantial amount of physical practice was required to reach an optimal speed. EEG results suggest the involvement of VST M for sequences that had less or no physical practice in both groups. The absence of differences between the motor imagery and the control group underlines the possibility that motor preparation may actually resemble motor imagery.

Spinal inhibition and motor function in adults with spastic cerebral palsy

PubMed Central

Condliffe, E. G.; Jeffery, D. T.; Emery, D. J.

2016-01-01

Key points Abnormal activation of motoneurons in the spinal cord by sensory pathways is thought to contribute to impaired movement control and spasticity in individuals with cerebral palsy.Here we use single motor unit recordings to show how individual motoneurons in the spinal cord respond to sensory inputs in a group of participants with cerebral palsy having different degrees of motor dysfunction.In participants who had problems walking independently and required assistive devices such as wheelchairs, sensory pathways only excited motoneurons in the spinal cord.In contrast, in participants with cerebral palsy who walked independently for long distances, sensory inputs both inhibited and excited motoneurons in the spinal cord, similar to what we found in uninjured control participants.These findings demonstrate that in individuals with severe cerebral palsy, inhibitory control of motoneurons from sensory pathways is reduced and may contribute to motor dysfunction and spasticity. Abstract Reduced inhibition of spinal motoneurons by sensory pathways may contribute to heightened reflex activity, spasticity and impaired motor function in individuals with cerebral palsy (CP). To measure if the activation of inhibitory post‐synaptic potentials (IPSPs) by sensory inputs is reduced in CP, the tonic discharge rate of single motor units from the soleus muscle was plotted time‐locked to the occurrence of a sensory stimulation to produce peri‐stimulus frequencygrams (PSFs). Stimulation to the medial arch of the foot was used to activate cutaneomuscular afferents in 17 adults with bilateral spastic CP and 15 neurologically intact (NI) peers. Evidence of IPSP activation from the PSF profiles, namely a marked pause or reduction in motor unit firing rates at the onset of the cutaneomuscular reflex, was found in all NI participants but in only half of participants with CP. In the other half of the participants with CP, stimulation of cutaneomuscular afferents produced a PSF

Memory deficits with intact cognitive control in the methylazoxymethanol acetate (MAM) exposure model of neurodevelopmental insult.

PubMed

O'Reilly, Kally C; Perica, Maria I; Fenton, André A

2016-10-01

Cognitive impairments are amongst the most debilitating deficits of schizophrenia and the best predictor of functional outcome. Schizophrenia is hypothesized to have a neurodevelopmental origin, making animal models of neurodevelopmental insult important for testing predictions that early insults will impair cognitive function. Rats exposed to methylazoxymethanol acetate (MAM) at gestational day 17 display morphological, physiological and behavioral abnormalities relevant to schizophrenia. Here we investigate the cognitive abilities of adult MAM rats. We examined brain activity in MAM rats by histochemically assessing cytochrome oxidase enzyme activity, a metabolic marker of neuronal activity. To assess cognition, we used a hippocampus-dependent two-frame active place avoidance paradigm to examine learning and spatial memory, as well as cognitive control and flexibility using the same environment and evaluating the same set of behaviors. We confirmed that adult MAM rats have altered hippocampal morphology and brain function, and that they are hyperactive in an open field. The latter likely indicates MAM rats have a sensorimotor gating deficit that is common to many animal models used for schizophrenia research. On first inspection, cognitive control seems impaired in MAM rats, indicated by more errors during the two-frame active place avoidance task. Because MAM rats are hyperactive throughout place avoidance training, we considered the possibility that the hyperlocomotion may account for the apparent cognitive deficits. These deficits were reduced on the basis of measures of cognitive performance that account for motor activity differences. However, though other aspects of memory are intact, the ability of MAM rats to express trial-to-trial memory is delayed compared to control rats. These findings suggest that spatial learning and cognitive abilities are largely intact, that the most prominent cognitive deficit is specific to acquiring memory in the MAM

The functional alterations associated with motor imagery training: a comparison between motor execution and motor imagery of sequential finger tapping

NASA Astrophysics Data System (ADS)

Zhang, Hang; Yao, Li; Long, Zhiying

2011-03-01

Motor imagery training, as an effective strategy, has been more and more applied to mental disorders rehabilitation and motor skill learning. Studies on the neural mechanism underlying motor imagery have suggested that such effectiveness may be related to the functional congruence between motor execution and motor imagery. However, as compared to the studies on motor imagery, the studies on motor imagery training are much fewer. The functional alterations associated with motor imagery training and the effectiveness of motor imagery training on motor performance improvement still needs further investigation. Using fMRI, we employed a sequential finger tapping paradigm to explore the functional alterations associated with motor imagery training in both motor execution and motor imagery task. We hypothesized through 14 consecutive days motor imagery training, the motor performance could be improved and the functional congruence between motor execution and motor imagery would be sustained form pre-training phase to post-training phase. Our results confirmed the effectiveness of motor imagery training in improving motor performance and demonstrated in both pre and post-training phases, motor imagery and motor execution consistently sustained the congruence in functional neuroanatomy, including SMA (supplementary motor cortex), PMA (premotor area); M1( primary motor cortex) and cerebellum. Moreover, for both execution and imagery tasks, a similar functional alteration was observed in fusiform through motor imagery training. These findings provided an insight into the effectiveness of motor imagery training and suggested its potential therapeutic value in motor rehabilitation.

(Photosynthesis in intact plants)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

Progress in the two years since the last renewal application has been excellent. We have made substantial contributions on both main fronts of the projects, and are particularly happy with the progress of our research on intact plants. The approach of basing our field work on a sound foundation of laboratory studies has enabled is to use methods which provide unambiguous assays of well characterized reactions. We have also made excellent progress in several laboratory studies which will have direct applications in future field work, and have introduced to the laboratory a range of molecular genetics techniques which will allowmore » us to explore new options in the attempt to understand function at the level of molecular structure.« less

Reflex control of discharge in motor fibres to the larynx

PubMed Central

Głogowska, Maria; Stransky, A.; Widdicombe, J. G.

1974-01-01

1. Action potentials have been recorded from single laryngeal motor fibres, with expiratory or inspiratory phases, in cats anaesthetized with pentobarbitone and breathing through a tracheal cannula. 2. Pneumothorax increased the discharge of both inspiratory and expiratory units, the inspiratory response being greatly reduced by bilateral vagotomy below the origin of the recurrent laryngeal nerves. 3. Addition of a `viscous' resistance to breathing, or asphyxial rebreathing through an added dead space, increased the activity of inspiratory units and decreased that of expiratory units. 4. Induction of pulmonary oedema decreased the discharge of inspiratory units and increased that of expiratory units. After vagotomy the response of inspiratory units was reversed. 5. Intravenous injections of potassium cyanide increased the activity of both types of unit. 6. Chemical irritation of the laryngeal mucosa decreased the discharge of inspiratory units and increased that of expiratory units, whether the vagi were intact or cut. 7. It is concluded that expiratory unit discharge can be correlated with expiratory laryngeal resistance, but that inspiratory unit discharge does not correlate so well with inspiratory laryngeal resistance. 8. The relationship between laryngeal motor-fibre activity and the contractions of the inspiratory and expiratory muscles of breathing is discussed. PMID:4415512

The heterotrimeric motor protein kinesin-II localizes to the midpiece and flagellum of sea urchin and sand dollar sperm.

PubMed

Henson, J H; Cole, D G; Roesener, C D; Capuano, S; Mendola, R J; Scholey, J M

1997-01-01

We have utilized immunoblotting and light microscopic immunofluorescent staining methods to examine the expression and localization of sea urchin kinesin-II, a heterotrimeric plus end-directed microtubule motor protein (previously referred to as KRP(85/95)), in sea urchin and sand dollar sperm. We demonstrate the presence of the 85 K and 115 K subunits of kinesin-II in sperm and localize these proteins to the sperm flagella and midpiece. The kinesin-II localization pattern is punctate and discontinuous, and in the flagella it is quite distinct from the continuous labeling present in sperm labeled with anti-flagellar dynein. The kinesin-II staining is largely insensitive to prefixation detergent extraction, suggesting that it is not associated with membranous elements in the sperm. In the midpiece the kinesin-II staining is similar to the pattern present in sperm labeled with an anti-centrosomal antibody. To our knowledge, this is the first localization of kinesin-like proteins in mature sperm and corroborates the recent identification and localization of kinesin-like proteins in the flagella and basal body of the unicellular green alga Chlamydomonas. We hypothesize that kinesin-II in the sperm may play functional roles in intraflagellar transport and/or the formation of flagella during spermatogenesis.

Central Projections of Antennal and Labial Palp Sensory Neurons in the Migratory Armyworm Mythimna separata

PubMed Central

Ma, Bai-Wei; Zhao, Xin-Cheng; Berg, Bente G.; Xie, Gui-Ying; Tang, Qing-Bo; Wang, Gui-Rong

2017-01-01

The oriental armyworm, Mythimna separata (Walker), is a polyphagous, migratory pest relying on olfactory cues to find mates, locate nectar, and guide long-distance flight behavior. In the present study, a combination of neuroanatomical techniques were utilized on this species, including backfills, confocal microscopy, and three-dimensional reconstructions, to trace the central projections of sensory neurons from the antenna and the labial pit organ, respectively. As previously shown, the axons of the labial sensory neurons project via the ipsilateral labial nerve and terminate in three main areas of the central nervous system: (1) the labial-palp pit organ glomerulus of each antennal lobe, (2) the gnathal ganglion, and (3) the prothoracic ganglion of the ventral nerve cord. Similarly, the antennal sensory axons project to multiple areas of the central nervous system. The ipsilateral antennal nerve targets mainly the antennal lobe, the antennal mechanosensory and motor center, and the prothoracic and mesothoracic ganglia. Specific staining experiments including dye application to each of the three antennal segments indicate that the antennal lobe receives input from flagellar olfactory neurons exclusively, while the antennal mechanosensory and motor center is innervated by mechanosensory neurons from the whole antenna, comprising the flagellum, pedicle, and scape. The terminals in the mechanosensory and motor center are organized in segregated zones relating to the origin of neurons. The flagellar mechanosensory axons target anterior zones, while the pedicular and scapal axons terminate in posterior zones. In the ventral nerve cord, the processes from the antennal sensory neurons terminate in the motor area of the thoracic ganglia, suggesting a close connection with motor neurons. Taken together, the numerous neuropils innervated by axons both from the antenna and labial palp indicate the multiple roles these sensory organs serve in insect behavior. PMID:29209176

Quantitation of Contacts Among Sensory, Motor, and Serotonergic Neurons in the Pedal Ganglion of Aplysia

PubMed Central

Zhang, Han; Wainwright, Marcy; Byrne, John H.; Cleary, Leonard J.

2003-01-01

Present models of long-term sensitization in Aplysia californica indicate that the enhanced behavioral response is due, at least in part, to outgrowth of sensory neurons mediating defensive withdrawal reflexes. Presumably, this outgrowth strengthens pre-existing connections by formation of newsynapses with follower neurons. However, the relationship between the number of sensorimotor contacts and the physiological strength of the connection has never been examined in intact ganglia. As a first step in addressing this issue, we used confocal microscopy to examine sites of contact between sensory and motor neurons in naive animals. Our results revealed relatively fewcontacts between physiologically connected cells. In addition, the number of contact sites was proportional to the amplitude of the EPSP elicited in the follower motor neuron by direct stimulation of the sensory neuron. This is the first time such a correlation has been observed in the central nervous system. Serotonin is the neurotransmitter most closely examined for its role in modulating synaptic strength at the sensorimotor synapse. However, the structural relationship of serotonergic processes and sensorimotor synapses has never been examined. Surprisingly, serotonergic processes usually made contact with sensory and motor neurons at sites located relatively distant from the sensorimotor synapse. This result implies that heterosynaptic regulation is due to nondirected release of serotonin into the neuropil. PMID:14557611

Losing a jewel—Rapid declines in Myanmar’s intact forests from 2002-2014

PubMed Central

Horning, Ned; Khaing, Thiri; Thein, Zaw Min; Aung, Kyaw Moe; Aung, Kyaw Htet; Phyo, Paing; Tun, Ye Lin; Oo, Aung Htat; Neil, Anthony; Thu, Win Myo; Songer, Melissa; Huang, Qiongyu; Connette, Grant; Leimgruber, Peter

2017-01-01

New and rapid political and economic changes in Myanmar are increasing the pressures on the country’s forests. Yet, little is known about the past and current condition of these forests and how fast they are declining. We mapped forest cover in Myanmar through a consortium of international organizations and environmental non-governmental groups, using freely-available public domain data and open source software tools. We used Landsat satellite imagery to assess the condition and spatial distribution of Myanmar’s intact and degraded forests with special focus on changes in intact forest between 2002 and 2014. We found that forests cover 42,365,729 ha or 63% of Myanmar, making it one of the most forested countries in the region. However, severe logging, expanding plantations, and degradation pose increasing threats. Only 38% of the country’s forests can be considered intact with canopy cover >80%. Between 2002 and 2014, intact forests declined at a rate of 0.94% annually, totaling more than 2 million ha forest loss. Losses can be extremely high locally and we identified 9 townships as forest conversion hotspots. We also delineated 13 large (>100,000 ha) and contiguous intact forest landscapes, which are dispersed across Myanmar. The Northern Forest Complex supports four of these landscapes, totaling over 6.1 million ha of intact forest, followed by the Southern Forest Complex with three landscapes, comprising 1.5 million ha. These remaining contiguous forest landscape should have high priority for protection. Our project demonstrates how open source data and software can be used to develop and share critical information on forests when such data are not readily available elsewhere. We provide all data, code, and outputs freely via the internet at (for scripts: https://bitbucket.org/rsbiodiv/; for the data: http://geonode.themimu.info/layers/geonode%3Amyan_lvl2_smoothed_dec2015_resamp) PMID:28520726

Production of high quality brain-derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B (TrkB) RNA from isolated populations of rat spinal cord motor neurons obtained by Laser Capture Microdissection (LCM).

PubMed

Mehta, Prachi; Premkumar, Brian; Morris, Renée

2016-08-03

The mammalian central nervous system (CNS) is composed of multiple cellular elements, making it challenging to segregate one particular cell type to study their gene expression profile. For instance, as motor neurons represent only 5-10% of the total cell population of the spinal cord, meaningful transcriptional analysis on these neurons is almost impossible to achieve from homogenized spinal cord tissue. A major challenge faced by scientists is to obtain good quality RNA from small amounts of starting material. In this paper, we used Laser Capture Microdissection (LCM) techniques to identify and isolate spinal cord motor neurons. The present analysis revealed that perfusion with paraformaldehyde (PFA) does not alter RNA quality. RNA integrity numbers (RINs) of tissue samples from rubrospinal tract (RST)-transected, intact spinal cord or from whole spinal cord homogenate were all above 8, which indicates intact, high-quality RNA. Levels of mRNA for brain-derived neurotrophic factor (BDNF) or for its tropomyosin receptor kinase B (TrkB) were not affected by rubrospinal tract (RST) transection, a surgical procedure that deprive motor neurons from one of their main supraspinal input. The isolation of pure populations of neurons with LCM techniques allows for robust transcriptional characterization that cannot be achieved with spinal cord homogenates. Such preparations of pure population of motor neurons will provide valuable tools to advance our understanding of the molecular mechanisms underlying spinal cord injury and neuromuscular diseases. In the near future, LCM techniques might be instrumental to the success of gene therapy for these debilitating conditions. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Neurons other than motor neurons in motor neuron disease.

PubMed

Ruffoli, Riccardo; Biagioni, Francesca; Busceti, Carla L; Gaglione, Anderson; Ryskalin, Larisa; Gambardella, Stefano; Frati, Alessandro; Fornai, Francesco

2017-11-01

Amyotrophic lateral sclerosis (ALS) is typically defined by a loss of motor neurons in the central nervous system. Accordingly, morphological analysis for decades considered motor neurons (in the cortex, brainstem and spinal cord) as the neuronal population selectively involved in ALS. Similarly, this was considered the pathological marker to score disease severity ex vivo both in patients and experimental models. However, the concept of non-autonomous motor neuron death was used recently to indicate the need for additional cell types to produce motor neuron death in ALS. This means that motor neuron loss occurs only when they are connected with other cell types. This concept originally emphasized the need for resident glia as well as non-resident inflammatory cells. Nowadays, the additional role of neurons other than motor neurons emerged in the scenario to induce non-autonomous motor neuron death. In fact, in ALS neurons diverse from motor neurons are involved. These cells play multiple roles in ALS: (i) they participate in the chain of events to produce motor neuron loss; (ii) they may even degenerate more than and before motor neurons. In the present manuscript evidence about multi-neuronal involvement in ALS patients and experimental models is discussed. Specific sub-classes of neurons in the whole spinal cord are reported either to degenerate or to trigger neuronal degeneration, thus portraying ALS as a whole spinal cord disorder rather than a disease affecting motor neurons solely. This is associated with a novel concept in motor neuron disease which recruits abnormal mechanisms of cell to cell communication.

T-type calcium channels cause bursts of spikes in motor but not sensory thalamic neurons during mimicry of natural patterns of synaptic input.

PubMed

Kim, Haram R; Hong, Su Z; Fiorillo, Christopher D

2015-01-01

Although neurons within intact nervous systems can be classified as 'sensory' or 'motor,' it is not known whether there is any general distinction between sensory and motor neurons at the cellular or molecular levels. Here, we extend and test a theory according to which activation of certain subtypes of voltage-gated ion channel (VGC) generate patterns of spikes in neurons of motor systems, whereas VGC are proposed to counteract patterns in sensory neurons. We previously reported experimental evidence for the theory from visual thalamus, where we found that T-type calcium channels (TtCCs) did not cause bursts of spikes but instead served the function of 'predictive homeostasis' to maximize the causal and informational link between retinogeniculate excitation and spike output. Here, we have recorded neurons in brain slices from eight sensory and motor regions of rat thalamus while mimicking key features of natural excitatory and inhibitory post-synaptic potentials. As predicted by theory, TtCC did cause bursts of spikes in motor thalamus. TtCC-mediated responses in motor thalamus were activated at more hyperpolarized potentials and caused larger depolarizations with more spikes than in visual and auditory thalamus. Somatosensory thalamus is known to be more closely connected to motor regions relative to auditory and visual thalamus, and likewise the strength of its TtCC responses was intermediate between these regions and motor thalamus. We also observed lower input resistance, as well as limited evidence of stronger hyperpolarization-induced ('H-type') depolarization, in nuclei closer to motor output. These findings support our theory of a specific difference between sensory and motor neurons at the cellular level.

Reflectance Spectra Comparison of Orbital Debris, Intact Spacecraft, and Intact Rocket Bodies in the GEO Regime

NASA Technical Reports Server (NTRS)

Barker, Ed; Abercromby, Kira J.; Abell, Paul

2009-01-01

A key objective of NASA s Orbital Debris program office at Johnson Space Center (JSC) is to characterize the debris environment by way of assessing the physical properties (type, mass, density, and size) of objects in orbit. Knowledge of the geosynchronous orbit (GEO) debris environment in particular can be used to determine the hazard probability at specific GEO altitudes and aid predictions of the future environment. To calculate an optical size from an intensity measurement of an object in the GEO regime, a 0.175 albedo is assumed currently. However, identification of specific material type or types could improve albedo accuracy and yield a more accurate size estimate for the debris piece. Using spectroscopy, it is possible to determine the surface materials of space objects. The study described herein used the NASA Infrared Telescope Facility (IRTF) to record spectral data in the 0.6 to 2.5 micron regime on eight catalogued space objects. For comparison, all of the objects observed were in GEO or near-GEO. The eight objects consisted of two intact spacecraft, three rocket bodies, and three catalogued debris pieces. Two of the debris pieces stemmed from Titan 3C transtage breakup and the third is from COSMOS 2054. The reflectance spectra of the Titan 3C pieces share similar slopes (increasing with wavelength) and lack any strong absorption features. The COSMOS debris spectra is flat and has no absorption features. In contrast, the intact spacecraft show classic absorption features due to solar panels with a strong band gap feature near 1 micron. The two spacecraft are spin-stabilized objects and therefore have solar panels surrounding the outer surface. Two of the three rocket bodies are inertial upper stage (IUS) rocket bodies and have similar looking spectra. The slopes flatten out near 1.5 microns with absorption features in the near-infrared that are similar to that of white paint. The third rocket body has a similar flattening of slope but with fewer

Reflectance Spectra Comparison of Orbital Debris, Intact Spacecraft, and Intact Rocket Bodies in the GEO Regime

NASA Astrophysics Data System (ADS)

Albercromby, Kira J.; Abell, Paul; Barker, Ed

2009-03-01

A key objective of NASA's Orbital Debris program office at Johnson Space Center (JSC) is to characterize the debris environment by way of assessing the physical properties (type, mass, density, and size) of objects in orbit. Knowledge of the geosynchronous orbit (GEO) debris environment in particular can be used to determine the hazard probability at specific GEO altitudes and aid predictions of the future environment. To calculate an optical size from an intensity measurement of an object in the GEO regime, a 0.175 albedo is assumed currently. However, identification of specific material type or types could improve albedo accuracy and yield a more accurate size estimate for the debris piece. Using spectroscopy, it is possible to determine the surface materials of space objects. The study described herein used the NASA Infrared Telescope Facility (IRTF) to record spectral data in the ~ 0.65 to 2.5 micron regime on eight catalogued space objects. For comparison, all of the objects observed were in GEO or near-GEO. The eight objects consisted of two intact spacecraft, three rocket bodies, and three catalogued debris pieces. Two of the debris pieces stemmed from Titan 3C transtage breakup and the third is from COSMOS 2054. The reflectance spectra of the Titan 3C pieces share similar slopes (increasing with wavelength) and lack any strong absorption features. The COSMOS debris spectrum has a slight slope and has no absorption features. In contrast, the intact spacecraft show classic absorption features due to solar cells with a strong band gap feature near 1 micron. The two spacecraft were spin-stabilized objects and therefore have solar panels surrounding the outer surface. Two of the three rocket bodies are inertial upper stage (IUS) rocket bodies and have similar looking spectra. The slopes flatten out near 1.5 microns with absorption features in the near-infrared that are similar to that of white paint. The third rocket body has a similar flattening of slope but

Motor "dexterity"?: Evidence that left hemisphere lateralization of motor circuit connectivity is associated with better motor performance in children.

PubMed

Barber, Anita D; Srinivasan, Priti; Joel, Suresh E; Caffo, Brian S; Pekar, James J; Mostofsky, Stewart H

2012-01-01

Motor control relies on well-established motor circuits, which are critical for typical child development. Although many imaging studies have examined task activation during motor performance, none have examined the relationship between functional intrinsic connectivity and motor ability. The current study investigated the relationship between resting state functional connectivity within the motor network and motor performance assessment outside of the scanner in 40 typically developing right-handed children. Better motor performance correlated with greater left-lateralized (mean left hemisphere-mean right hemisphere) motor circuit connectivity. Speed, rhythmicity, and control of movements were associated with connectivity within different individual region pairs: faster speed was associated with more left-lateralized putamen-thalamus connectivity, less overflow with more left-lateralized supplementary motor-primary motor connectivity, and less dysrhythmia with more left-lateralized supplementary motor-anterior cerebellar connectivity. These findings suggest that for right-handed children, superior motor development depends on the establishment of left-hemisphere dominance in intrinsic motor network connectivity.

Motor current signature analysis method for diagnosing motor operated devices

DOEpatents

Haynes, Howard D.; Eissenberg, David M.

1990-01-01

A motor current noise signature analysis method and apparatus for remotely monitoring the operating characteristics of an electric motor-operated device such as a motor-operated valve. Frequency domain signal analysis techniques are applied to a conditioned motor current signal to distinctly identify various operating parameters of the motor driven device from the motor current signature. The signature may be recorded and compared with subsequent signatures to detect operating abnormalities and degradation of the device. This diagnostic method does not require special equipment to be installed on the motor-operated device, and the current sensing may be performed at remote control locations, e.g., where the motor-operated devices are used in accessible or hostile environments.

Predicting explorative motor learning using decision-making and motor noise.

PubMed

Chen, Xiuli; Mohr, Kieran; Galea, Joseph M

2017-04-01

A fundamental problem faced by humans is learning to select motor actions based on noisy sensory information and incomplete knowledge of the world. Recently, a number of authors have asked whether this type of motor learning problem might be very similar to a range of higher-level decision-making problems. If so, participant behaviour on a high-level decision-making task could be predictive of their performance during a motor learning task. To investigate this question, we studied performance during an explorative motor learning task and a decision-making task which had a similar underlying structure with the exception that it was not subject to motor (execution) noise. We also collected an independent measurement of each participant's level of motor noise. Our analysis showed that explorative motor learning and decision-making could be modelled as the (approximately) optimal solution to a Partially Observable Markov Decision Process bounded by noisy neural information processing. The model was able to predict participant performance in motor learning by using parameters estimated from the decision-making task and the separate motor noise measurement. This suggests that explorative motor learning can be formalised as a sequential decision-making process that is adjusted for motor noise, and raises interesting questions regarding the neural origin of explorative motor learning.

Predicting explorative motor learning using decision-making and motor noise

PubMed Central

Galea, Joseph M.

2017-01-01

A fundamental problem faced by humans is learning to select motor actions based on noisy sensory information and incomplete knowledge of the world. Recently, a number of authors have asked whether this type of motor learning problem might be very similar to a range of higher-level decision-making problems. If so, participant behaviour on a high-level decision-making task could be predictive of their performance during a motor learning task. To investigate this question, we studied performance during an explorative motor learning task and a decision-making task which had a similar underlying structure with the exception that it was not subject to motor (execution) noise. We also collected an independent measurement of each participant’s level of motor noise. Our analysis showed that explorative motor learning and decision-making could be modelled as the (approximately) optimal solution to a Partially Observable Markov Decision Process bounded by noisy neural information processing. The model was able to predict participant performance in motor learning by using parameters estimated from the decision-making task and the separate motor noise measurement. This suggests that explorative motor learning can be formalised as a sequential decision-making process that is adjusted for motor noise, and raises interesting questions regarding the neural origin of explorative motor learning. PMID:28437451

Silica Aerogel Captures Cosmic Dust Intact

NASA Technical Reports Server (NTRS)

Tsou, P.

1994-01-01

The mesostructure of silica aerogel resembles stings of grapes, ranging in size from 10 to 100 angstrom. This fine mesostructure transmits nearly 90 percent of incident light in the visible, while providing sufficiently gentle dissipation of the kinetric energy of hypervelocity cosmic dust particles to permit their intact capture. We introduced silica aerogel in 1987 as capture medium to take advantage of its low density, fine mesostruicture and most importantly, its transparency, allowing optical location of captured micron sized particles.

The Relative Impact of Sleep and Circadian Drive on Motor Skill Acquisition and Memory Consolidation.

PubMed

Tucker, Matthew A; Morris, Christopher J; Morgan, Alexandra; Yang, Jessica; Myers, Samantha; Pierce, Joanna Garcia; Stickgold, Robert; Scheer, Frank A J L

2017-04-01

Sleep during the biological night facilitates memory consolidation. Here we determined the impact of sleep and wake on motor skill learning (acquisition) and subsequent off-line skill improvement (memory consolidation), independent of circadian phase, and compared this to the impact of the endogenous circadian system, independent of whether sleep occurred during the biological night or day. Participants completed two 8-day sleep laboratory visits, adhering on one visit to a circadian aligned ("normal") sleep schedule for the full duration of the protocol, and on the other to a circadian misaligned (12-hour inverted) schedule, with alignment during the first 3 days, a 12-hour 'slam shift' on Day 4, followed by circadian misalignment during the last 4 days of the protocol. Participants were repeatedly trained and tested on different versions of the finger-tapping motor sequence task across each visit. Sleep facilitated offline memory consolidation regardless of whether it occurred during the biological day or night, while circadian phase had no significant impact. These sleep-related benefits remained after accounting for general motor speed, measured in the absence of learning. In addition, motor skill acquisition was facilitated when the training session followed shortly after sleep, without significant impact of circadian phase (biological morning vs. evening). This effect was largely driven by heightened acquisition in participants who slept during the day and were trained shortly thereafter, that is, when acquisition occurred during the biological evening. These benefits were also retained after controlling for general motor speed. Sleep benefits both the acquisition and consolidation of motor skill regardless of whether they occur during the biological day or night. After controlling for general motor speed, a critical adjustment that few studies perform, these sleep benefits remain intact. Our findings have clear implications for night shift workers who obtain

Function of the conserved FHIPEP domain of the flagellar type III export apparatus, protein FlhA.

PubMed

Barker, Clive S; Inoue, Tomoharu; Meshcheryakova, Irina V; Kitanobo, Seiya; Samatey, Fadel A

2016-04-01

The Type III flagellar protein export apparatus of bacteria consists of five or six membrane proteins, notably FlhA, which controls the export of other proteins and is homologous to the large family of FHIPEP export proteins. FHIPEP proteins contain a highly-conserved cytoplasmic domain. We mutagenized the cloned Salmonella flhA gene for the 692 amino acid FlhA, changing a single, conserved amino acid in the 68-amino acid FHIPEP region. Fifty-two mutations at 30 positions mostly led to loss of motility and total disappearance of microscopically visible flagella, also Western blot protein/protein hybridization showed no detectable export of hook protein and flagellin. There were two exceptions: a D199A mutant strain, which produced short-stubby flagella; and a V151L mutant strain, which did not produce flagella and excreted mainly un-polymerized hook protein. The V151L mutant strain also exported a reduced amount of hook-cap protein FlgD, but when grown with exogenous FlgD it produced polyhooks and polyhook-filaments. A suppressor mutant in the cytoplasmic domain of the export apparatus membrane protein FlhB rescued export of hook-length control protein FliK and facilitated growth of full-length flagella. These results suggested that the FHIPEP region is part of the gate regulating substrate entry into the export apparatus pore. © 2015 John Wiley & Sons Ltd.

46 CFR 169.684 - Overcurrent protection for motors and motor branch circuits.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Overcurrent protection for motors and motor branch... motors and motor branch circuits. (a) Except as provided in paragraph (d) of this section, each motor... motor that is responsive to motor current or to both motor current and temperature may be used. (b) The...

Aberrant supplementary motor complex and limbic activity during motor preparation in motor conversion disorder

PubMed Central

Voon, V; Brezing, C; Gallea, C; Hallett, M

2014-01-01

Background Conversion disorder is characterized by unexplained neurological symptoms presumed related to psychological issues. The main hypotheses to explain conversion paralysis, characterized by a lack of movement, include impairments in either motor intention or disruption of motor execution, and further, that hyperactive self-monitoring, limbic processing or top-down regulation from higher order frontal regions may interfere with motor execution. We have recently shown that conversion disorder with positive abnormal or excessive motor symptoms was associated with greater amygdala activity to arousing stimuli along with greater functional connectivity between the amgydala and supplementary motor area. Here we studied patients with such symptoms focusing on motor initiation. Methods Subjects performed either an internally or externally generated two-button action selection task in a functional MRI study. Results Eleven conversion disorder patients without major depression and 11 age- and gender-matched normal volunteers were assessed. During both internally and externally generated movement, conversion disorder patients relative to normal volunteers had lower left supplementary motor area (SMA) (implicated in motor initiation) and higher right amygdala, left anterior insula and bilateral posterior cingulate activity (implicated in assigning emotional salience). These findings were confirmed in a subgroup analysis of patients with tremor symptoms. During internally versus externally generated action in CD patients, the left SMA had lower functional connectivity with bilateral dorsolateral prefrontal cortices. Conclusion We propose a theory in which previously mapped conversion motor representations may in an arousing context hijack the voluntary action selection system which is both hypoactive and functionally disconnected from prefrontal top-down regulation. PMID:21935985

Aberrant supplementary motor complex and limbic activity during motor preparation in motor conversion disorder.

PubMed

Voon, Valerie; Brezing, Christina; Gallea, Cecile; Hallett, Mark

2011-11-01

Conversion disorder (CD) is characterized by unexplained neurological symptoms presumed related to psychological issues. The main hypotheses to explain conversion paralysis, characterized by a lack of movement, include impairments in either motor intention or disruption of motor execution, and further, that hyperactive self-monitoring, limbic processing or top-down regulation from higher order frontal regions may interfere with motor execution. We have recently shown that CD with positive abnormal or excessive motor symptoms was associated with greater amygdala activity to arousing stimuli along with greater functional connectivity between the amygdala and supplementary motor area. Here we studied patients with such symptoms focusing on motor initiation. Subjects performed either an internally or externally generated 2-button action selection task in a functional MRI study. Eleven CD patients without major depression and 11 age- and gender-matched normal volunteers were assessed. During both internally and externally generated movement, conversion disorder patients relative to normal volunteers had lower left supplementary motor area (SMA) (implicated in motor initiation) and higher right amygdala, left anterior insula, and bilateral posterior cingulate activity (implicated in assigning emotional salience). These findings were confirmed in a subgroup analysis of patients with tremor symptoms. During internally versus externally generated action in CD patients, the left SMA had lower functional connectivity with bilateral dorsolateral prefrontal cortices. We propose a theory in which previously mapped conversion motor representations may in an arousing context hijack the voluntary action selection system, which is both hypoactive and functionally disconnected from prefrontal top-down regulation. Copyright © 2011 Movement Disorder Society.

Motor/generator

DOEpatents

Hickam, Christopher Dale [Glasford, IL

2008-05-13

A motor/generator is provided for connecting between a transmission input shaft and an output shaft of a prime mover. The motor/generator may include a motor/generator housing, a stator mounted to the motor/generator housing, a rotor mounted at least partially within the motor/generator housing and rotatable about a rotor rotation axis, and a transmission-shaft coupler drivingly coupled to the rotor. The transmission-shaft coupler may include a clamp, which may include a base attached to the rotor and a plurality of adjustable jaws.

41 CFR 102-34.85 - What motor vehicles require motor vehicle identification?

Code of Federal Regulations, 2014 CFR

2014-01-01

... require motor vehicle identification? 102-34.85 Section 102-34.85 Public Contracts and Property Management... 34-MOTOR VEHICLE MANAGEMENT Identifying and Registering Motor Vehicles Motor Vehicle Identification § 102-34.85 What motor vehicles require motor vehicle identification? All Government motor vehicles must...

41 CFR 102-34.85 - What motor vehicles require motor vehicle identification?

Code of Federal Regulations, 2012 CFR

2012-01-01

... require motor vehicle identification? 102-34.85 Section 102-34.85 Public Contracts and Property Management... 34-MOTOR VEHICLE MANAGEMENT Identifying and Registering Motor Vehicles Motor Vehicle Identification § 102-34.85 What motor vehicles require motor vehicle identification? All Government motor vehicles must...

41 CFR 102-34.85 - What motor vehicles require motor vehicle identification?

Code of Federal Regulations, 2010 CFR

2010-07-01

... require motor vehicle identification? 102-34.85 Section 102-34.85 Public Contracts and Property Management... 34-MOTOR VEHICLE MANAGEMENT Identifying and Registering Motor Vehicles Motor Vehicle Identification § 102-34.85 What motor vehicles require motor vehicle identification? All Government motor vehicles must...

41 CFR 102-34.85 - What motor vehicles require motor vehicle identification?

Code of Federal Regulations, 2011 CFR

2011-01-01

... require motor vehicle identification? 102-34.85 Section 102-34.85 Public Contracts and Property Management... 34-MOTOR VEHICLE MANAGEMENT Identifying and Registering Motor Vehicles Motor Vehicle Identification § 102-34.85 What motor vehicles require motor vehicle identification? All Government motor vehicles must...

41 CFR 102-34.85 - What motor vehicles require motor vehicle identification?

Code of Federal Regulations, 2013 CFR

2013-07-01

... require motor vehicle identification? 102-34.85 Section 102-34.85 Public Contracts and Property Management... 34-MOTOR VEHICLE MANAGEMENT Identifying and Registering Motor Vehicles Motor Vehicle Identification § 102-34.85 What motor vehicles require motor vehicle identification? All Government motor vehicles must...

Mass distribution and spatial organization of the linear bacterial motor of Spiroplasma citri R8A2.

PubMed

Trachtenberg, Shlomo; Andrews, S Brian; Leapman, Richard D

2003-03-01

In the simple, helical, wall-less bacterial genus Spiroplasma, chemotaxis and motility are effected by a linear, contractile motor arranged as a flat cytoskeletal ribbon attached to the inner side of the membrane along the shortest helical line. With scanning transmission electron microscopy and diffraction analysis, we determined the hierarchical and spatial organization of the cytoskeleton of Spiroplasma citri R8A2. The structural unit appears to be a fibril, approximately 5 nm wide, composed of dimers of a 59-kDa protein; each ribbon is assembled from seven fibril pairs. The functional unit of the intact ribbon is a pair of aligned fibrils, along which pairs of dimers form tetrameric ring-like repeats. On average, isolated and purified ribbons contain 14 fibrils or seven well-aligned fibril pairs, which are the same structures observed in the intact cell. Scanning transmission electron microscopy mass analysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of purified cytoskeletons indicate that the 59-kDa protein is the only constituent of the ribbons.

Aboveground Biomass Variability Across Intact and Degraded Forests in the Brazilian Amazon

NASA Technical Reports Server (NTRS)

Longo, Marcos; Keller, Michael; Dos-Santos, Maiza N.; Leitold, Veronika; Pinage, Ekena R.; Baccini, Alessandro; Saatchi, Sassan; Nogueira, Euler M.; Batistella, Mateus; Morton, Douglas C.

2016-01-01

Deforestation rates have declined in the Brazilian Amazon since 2005, yet degradation from logging, re, and fragmentation has continued in frontier forests. In this study we quantified the aboveground carbon density (ACD) in intact and degraded forests using the largest data set of integrated forest inventory plots (n 359) and airborne lidar data (18,000 ha) assembled to date for the Brazilian Amazon. We developed statistical models relating inventory ACD estimates to lidar metrics that explained70 of the variance across forest types. Airborne lidar-ACD estimates for intact forests ranged between 5.0 +/- 2.5 and 31.9 +/- 10.8 kg C m(exp -2). Degradation carbon losses were large and persistent. Sites that burned multiple times within a decade lost up to 15.0 +/- 0.7 kg C m(-2)(94%) of ACD. Forests that burned nearly15 years ago had between 4.1 +/- 0.5 and 6.8 +/- 0.3 kg C m(exp -2) (22-40%) less ACD than intact forests. Even for low-impact logging disturbances, ACD was between 0.7 +/- 0.3 and 4.4 +/- 0.4 kg C m(exp -2)(4-21%) lower than unlogged forests. Comparing biomass estimates from airborne lidar to existing biomass maps, we found that regional and pan-tropical products consistently overestimated ACD in degraded forests, under-estimated ACD in intact forests, and showed little sensitivity to res and logging. Fine-scale heterogeneity in ACD across intact and degraded forests highlights the benefits of airborne lidar for carbon mapping. Differences between airborne lidar and regional biomass maps underscore the need to improve and update biomass estimates for dynamic land use frontiers, to better characterize deforestation and degradation carbon emissions for regional carbon budgets and Reduce Emissions from Deforestation and forest Degradation(REDD+).

Developmental amnesia: a new pattern of dissociation with intact episodic memory.

PubMed

Temple, Christine M; Richardson, Paul

2004-01-01

A case of developmental amnesia is reported for a child, CL, of normal intelligence, who has intact episodic memory but impaired semantic memory for both semantic knowledge of facts and semantic knowledge of words, including general world knowledge, knowledge of word meanings and superordinate knowledge of words. In contrast to the deficits in semantic memory, there are no impairments in episodic memory for verbal or visual material, assessed by recall or recognition. Lexical decision was also intact, indicating impairment in semantic knowledge of vocabulary rather than absence of lexical representations. The case forms a double dissociation to the cases of Vargha-Khadem et al. [Science 277 (1997) 376; Episodic memory: new directions in research (2002) 153]; Gadian et al. [Brain 123 (2000) 499] for whom semantic memory was intact but episodic memory was impaired. This double dissociation suggests that semantic memory and episodic memory have the capacity to develop separately and supports models of modularity within memory development and a functional architecture for the developmental disorders within which there is residual normality rather than pervasive abnormality. Knowledge of arithmetical facts is also spared for CL, consistent with adult studies arguing for numeracy knowledge distinct from other semantics. Reading was characterised by difficulty with irregular words and homophones but intact reading of nonwords. CL has surface dyslexia with poor lexico-semantic reading skills but good phonological reading skills. The case was identified following screening from a population of normal schoolchildren suggesting that developmental amnesias may be more pervasive than has been recognised previously.

Not GABA but glycine mediates segmental, propriospinal, and bulbospinal postsynaptic inhibition in adult mouse spinal forelimb motor neurons.

PubMed

Jiang, Juan; Alstermark, Bror

2015-02-04

The general view is that both glycine (Eccles, 1964) and GABA (Curtis and Felix, 1971) evoke postsynaptic inhibition in spinal motor neurons. In newborn or juvenile animals, there are conflicting results showing postsynaptic inhibition in motor neurons by corelease of GABA and glycine (Jonas et al., 1998) or by glycine alone (Bhumbra et al., 2012). To resolve the relative contributions of GABA and glycine to postsynaptic inhibition, we performed in vivo intracellular recordings from forelimb motor neurons in adult mice. Postsynaptic potentials evoked from segmental, propriospinal, and bulbospinal systems in motor neurons were compared across four different conditions: control, after gabazine, gabazine followed by strychnine, and strychnine alone. No significant differences were observed in the proportion of IPSPs and EPSPs between control and gabazine conditions. In contrast, EPSPs but not IPSPs were recorded after adding strychnine with gabazine or administering strychnine alone, suggesting an exclusive role for glycine in postsynaptic inhibition. To test whether the injected (intraperitoneal) dose of gabazine blocked GABAergic inhibitory transmission, we evoked GABAA receptor-mediated monosynaptic IPSPs in deep cerebellar nuclei neurons by stimulation of Purkinje cell fibers. No monosynaptic IPSPs could be recorded in the presence of gabazine, showing the efficacy of gabazine treatment. Our results demonstrate that, in the intact adult mouse, the postsynaptic inhibitory effects in spinal motor neurons exerted by three different systems, intrasegmental and intersegmental as well as supraspinal, are exclusively glycinergic. These findings emphasize the importance of glycinergic postsynaptic inhibition in motor neurons and challenge the view that GABA also contributes. Copyright © 2015 the authors 0270-6474/15/351991-08$15.00/0.

Overexpression of human mutated G93A SOD1 changes dynamics of the ER mitochondria calcium cycle specifically in mouse embryonic motor neurons.

PubMed

Lautenschläger, Janin; Prell, Tino; Ruhmer, Julia; Weidemann, Lisa; Witte, Otto W; Grosskreutz, Julian

2013-09-01

Motor neurons vulnerable to the rapidly progressive deadly neurodegenerative disease amyotrophic lateral sclerosis (ALS) inherently express low amounts of calcium binding proteins (CaBP), likely to allow physiological motor neuron firing frequency modulation. At the same time motor neurons are susceptible to AMPA receptor mediated excitotoxicity and internal calcium deregulation which is not fully understood. We analysed ER mitochondria calcium cycle (ERMCC) dynamics with subsecond resolution in G93A hSOD1 overexpressing motor neurons as a model of ALS using fluorescent calcium imaging. When comparing vulnerable motor neurons and non-motor neurons from G93A hSOD1 mice and their non-transgenic littermates, we found a decelerated cytosolic calcium clearance in the presence of G93A hSOD1. While both non-transgenic as well as G93A hSOD1 motor neurons displayed large mitochondrial calcium uptake by the mitochondrial uniporter (mUP), the mitochondrial calcium extrusion system was altered in the presence of G93A hSOD1. In addition, ER calcium uptake by the sarco-/endoplasmic reticulum ATPase (SERCA) was increased in G93A hSOD1 motor neurons. In survival assays, blocking the mitochondrial sodium calcium exchanger (mNCE) by CGP37157 as well as inhibiting SERCA by cyclopiazonic acid showed protective effects against kainate induced excitotoxicity. Thus, our study shows for the first time that the functional consequence of G93A hSOD1 overexpression in intact motor neurons is indeed a disturbance of the ER mitochondria calcium cycle, and identified two promising targets for therapeutic intervention in the pathology of ALS. Copyright © 2013 Elsevier Inc. All rights reserved.

Comparison of functional recovery of manual dexterity after unilateral spinal cord lesion or motor cortex lesion in adult macaque monkeys.

PubMed

Hoogewoud, Florence; Hamadjida, Adjia; Wyss, Alexander F; Mir, Anis; Schwab, Martin E; Belhaj-Saif, Abderraouf; Rouiller, Eric M

2013-01-01

In relation to mechanisms involved in functional recovery of manual dexterity from cervical cord injury or from motor cortical injury, our goal was to determine whether the movements that characterize post-lesion functional recovery are comparable to original movement patterns or do monkeys adopt distinct strategies to compensate the deficits depending on the type of lesion? To this aim, data derived from earlier studies, using a skilled finger task (the modified Brinkman board from which pellets are retrieved from vertical or horizontal slots), in spinal cord and motor cortex injured monkeys were analyzed and compared. Twelve adult macaque monkeys were subjected to a hemi-section of the cervical cord (n = 6) or to a unilateral excitotoxic lesion of the hand representation in the primary motor cortex (n = 6). In addition, in each subgroup, one half of monkeys (n = 3) were treated for 30 days with a function blocking antibody against the neurite growth inhibitory protein Nogo-A, while the other half (n = 3) represented control animals. The motor deficits, and the extent and time course of functional recovery were assessed. For some of the parameters investigated (wrist angle for horizontal slots and movement types distribution for vertical slots after cervical injury; movement types distribution for horizontal slots after motor cortex lesion), post-lesion restoration of the original movement patterns ("true" recovery) led to a quantitatively better functional recovery. In the motor cortex lesion groups, pharmacological reversible inactivation experiments showed that the peri-lesion territory of the primary motor cortex or re-arranged, spared domain of the lesion zone, played a major role in the functional recovery, together with the ipsilesional intact premotor cortex.

Sympathetic Nervous Regulation of Calcium and Action Potential Alternans in the Intact Heart.

PubMed

Winter, James; Bishop, Martin J; Wilder, Catherine D E; O'Shea, Christopher; Pavlovic, Davor; Shattock, Michael J

2018-01-01

Rationale: Arrhythmogenic cardiac alternans are thought to be an important determinant for the initiation of ventricular fibrillation. There is limited information on the effects of sympathetic nerve stimulation (SNS) on alternans in the intact heart and the conclusions of existing studies, focused on investigating electrical alternans, are conflicted. Meanwhile, several lines of evidence implicate instabilities in Ca handling, not electrical restitution, as the primary mechanism underpinning alternans. Despite this, there have been no studies on Ca alternans and SNS in the intact heart. The present study sought to address this, by application of voltage and Ca optical mapping for the simultaneous study of APD and Ca alternans in the intact guinea pig heart during direct SNS. Objective : To determine the effects of SNS on APD and Ca alternans in the intact guinea pig heart and to examine the mechanism(s) by which the effects of SNS are mediated. Methods and Results : Studies utilized simultaneous voltage and Ca optical mapping in isolated guinea pig hearts with intact innervation. Alternans were induced using a rapid dynamic pacing protocol. SNS was associated with rate-independent shortening of action potential duration (APD) and the suppression of APD and Ca alternans, as indicated by a shift in the alternans threshold to faster pacing rates. Qualitatively similar results were observed with exogenous noradrenaline perfusion. In contrast with previous reports, both SNS and noradrenaline acted to flatten the slope of the electrical restitution curve. Pharmacological block of the slow delayed rectifying potassium current (I Ks ), sufficient to abolish I Ks -mediated APD-adaptation, partially reversed the effects of SNS on pacing-induced alternans. Treatment with cyclopiazonic acid, an inhibitor of the sarco(endo)plasmic reticulum ATPase, had opposite effects to that of SNS, acting to increase susceptibility to alternans, and suggesting that accelerated Ca reuptake

Space shuttle Production Verification Motor 1 (PV-1) static fire

NASA Technical Reports Server (NTRS)

1989-01-01

All inspection and instrumentation data indicate that the PV-1 static test firing conducted 18 Aug. 1988 was successful. With the exception of the intentionally flawed joints and static test modifications, PV-1 was flight configuration. Fail-safe flaws guaranteeing pressure to test the sealing capability of primary O-rings were included in the aft field joint, case-to-nozzle joint, and nozzle internal Joint 5. The test was conducted at ambient conditions, with the exception of the field joints and case/nozzle joints which were maintained at a minimum of 75 F. Ballistics performance values were within specification requirements. The PV-1 motor exhibited chamber pressure oscillations similar to previously tested Space Shuttle redesigned solid rocket motors, particularly QM-7. The first longitudinal mode oscillations experienced by PV-1 were the strongest ever measured in a Space Shuttle motor. Investigation into this observation is being conducted. Joint insulation performed as designed with no evidence of gas flow within unflawed forward field joints. The intentionally flawed center and aft case field joint insulation performance was excellent. There was no evidence of hot gas past the center field joint capture feature O-ring, the case-to-nozzle joint primary O-ring, or the aft field joint primary O-ring. O-ring seals and barriers with assured pressure at the flaws showed erosion and heat effect, but all sealed against passage of hot gases with the exception of the aft field joint capture feature O-ring. There was no evidence of erosion, heat effect, or blowby on any O-ring seals or barriers at the unflawed joints. Nozzle performance was nominal with typical erosion. Post-test examination revealed that the forward nose ring was of the old high performance motor design configuration with the 150-deg ply angle. All nozzle components remained intact for post-test evaluation. The thrust vector control system operated correctly. The water deluge system, CO2 quench, and

Performance Comparison between a Permanent Magnet Synchronous Motor and an Induction Motor as a Traction Motor for High Speed Train

NASA Astrophysics Data System (ADS)

Kondo, Minoru; Kawamura, Junya; Terauchi, Nobuo

Performance tests are carried out to demonstrate the superiority of a permanent magnet synchronous motor to an induction motor as a traction motor for high-speed train. A prototype motor was manufactured by replacing the rotor of a conventional induction motor. The test results show that the permanent magnet motor is lighter, efficient and more silent than the induction motor because of the different rotor structure.

Predictors of attachment security in preschool children from intact and divorced families.

PubMed

Nair, Hira; Murray, Ann D

2005-09-01

The authors selected 58 mother-child dyads from divorced and intact families to participate in a study on the impact of divorce on preschoolers' attachment security. The authors explored pathways that lead to security of attachment. They found that mothers from divorced families were younger, had lower income levels, and had lower levels of education compared with their intact counterparts. Divorced mothers also reported significantly higher levels of stress, depression, need for social support, and conflict with their spouses. Mothers from intact families were more likely to use positive (authoritative) parenting styles compared with divorced mothers. Children in the divorced group had lower security scores on the Attachment Q-Set instrument (E. Waters, 1995). Regression analyses indicated that parenting style made a direct (independent) contribution to attachment security. In addition, temperament was related to attachment security, but temperament did not diminish the association of parenting style with attachment security. Furthermore, regression analyses indicated that the relationship of divorce to attachment security was mediated by parenting style.

Genetic noise mechanism for power-law switching in bacterial flagellar motors

NASA Astrophysics Data System (ADS)

Krivonosov, M. I.; Zaburdaev, V.; Denisov, S. V.; Ivanchenko, M. V.

2018-06-01

Switching of the direction of flagella rotations is the key control mechanism governing the chemotactic activity of E. coli and many other bacteria. Power-law distributions of switching times are most peculiar because their emergence cannot be deduced from simple thermodynamic arguments. Recently, it was suggested that by adding finite-time correlations into Gaussian fluctuations regulating the energy height of the barrier between the two rotation states, it is possible to generate switching statistics with an intermediate power-law asymptotics. By using a simple model of a regulatory pathway, we demonstrate that the required amount of correlated ‘noise’ can be produced by finite number fluctuations of reacting protein molecules, a condition common to the intracellular chemistry. The corresponding power-law exponent appears as a tunable characteristic controlled by parameters of the regulatory pathway network such as the equilibrium number of molecules, sensitivities, and the characteristic relaxation time.

Toward best practices in data processing and analysis for intact biotherapeutics by MS in quantitative bioanalysis.

PubMed

Kellie, John F; Kehler, Jonathan R; Karlinsey, Molly Z; Summerfield, Scott G

2017-12-01

Typically, quantitation of biotherapeutics from biological matrices by LC-MS is based on a surrogate peptide approach to determine molecule concentration. Recent efforts have focused on quantitation of the intact protein molecules or larger mass subunits of monoclonal antibodies. To date, there has been limited guidance for large or intact protein mass quantitation for quantitative bioanalysis. Intact- and subunit-level analyses of biotherapeutics from biological matrices are performed at 12-25 kDa mass range with quantitation data presented. Linearity, bias and other metrics are presented along with recommendations made on the viability of existing quantitation approaches. This communication is intended to start a discussion around intact protein data analysis and processing, recognizing that other published contributions will be required.

System and method for motor speed estimation of an electric motor

DOEpatents

Lu, Bin [Kenosha, WI; Yan, Ting [Brookfield, WI; Luebke, Charles John [Sussex, WI; Sharma, Santosh Kumar [Viman Nagar, IN

2012-06-19

A system and method for a motor management system includes a computer readable storage medium and a processing unit. The processing unit configured to determine a voltage value of a voltage input to an alternating current (AC) motor, determine a frequency value of at least one of a voltage input and a current input to the AC motor, determine a load value from the AC motor, and access a set of motor nameplate data, where the set of motor nameplate data includes a rated power, a rated speed, a rated frequency, and a rated voltage of the AC motor. The processing unit is also configured to estimate a motor speed based on the voltage value, the frequency value, the load value, and the set of nameplate data and also store the motor speed on the computer readable storage medium.

SOLITARY CHEMORECEPTOR CELL SURVIVAL IS INDEPENDENT OF INTACT TRIGEMINAL INNERVATION

PubMed Central

Gulbransen, Brian; Silver, Wayne; Finger, Tom

2008-01-01

Nasal solitary chemoreceptor cells (SCCs) are a population of specialized chemosensory epithelial cells presumed to broaden trigeminal chemoreceptivity in mammals (Finger et al., 2003). SCCs are innervated by peptidergic trigeminal nerve fibers (Finger et al., 2003) but it is currently unknown if intact innervation is necessary for SCC development or survival. We tested the dependence of SCCs on innervation by eliminating trigeminal nerve fibers during development with neurogenin-1 knockout mice, during early postnatal development with capsaicin desensitization, and during adulthood with trigeminal lesioning. Our results demonstrate that elimination of innervation at any of these times does not result in decreased SCC numbers. In conclusion, neither SCC development nor mature cell maintenance is dependent on intact trigeminal innervation. PMID:18300260

Loss of FliL alters Proteus mirabilis surface sensing and temperature-dependent swarming.

PubMed

Lee, Yi-Ying; Belas, Robert

2015-01-01

Proteus mirabilis is a dimorphic motile bacterium well known for its flagellum-dependent swarming motility over surfaces. In liquid, P. mirabilis cells are 1.5- to 2.0-μm swimmer cells with 4 to 6 flagella. When P. mirabilis encounters a solid surface, where flagellar rotation is limited, swimmer cells differentiate into elongated (10- to 80-μm), highly flagellated swarmer cells. In order for P. mirabilis to swarm, it first needs to detect a surface. The ubiquitous but functionally enigmatic flagellar basal body protein FliL is involved in P. mirabilis surface sensing. Previous studies have suggested that FliL is essential for swarming through its involvement in viscosity-dependent monitoring of flagellar rotation. In this study, we constructed and characterized ΔfliL mutants of P. mirabilis and Escherichia coli. Unexpectedly and unlike other fliL mutants, both P. mirabilis and E. coli ΔfliL cells swarm (Swr(+)). Further analysis revealed that P. mirabilis ΔfliL cells also exhibit an alteration in their ability to sense a surface: e.g., ΔfliL P. mirabilis cells swarm precociously over surfaces with low viscosity that normally impede wild-type swarming. Precocious swarming is due to an increase in the number of elongated swarmer cells in the population. Loss of fliL also results in an inhibition of swarming at <30°C. E. coli ΔfliL cells also exhibit temperature-sensitive swarming. These results suggest an involvement of FliL in the energetics and function of the flagellar motor. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Method for assessing motor insulation on operating motors

DOEpatents

Kueck, John D.; Otaduy, Pedro J.

1997-01-01

A method for monitoring the condition of electrical-motor-driven devices. The method is achieved by monitoring electrical variables associated with the functioning of an operating motor, applying these electrical variables to a three phase equivalent circuit and determining non-symmetrical faults in the operating motor based upon symmetrical components analysis techniques.

Motor experience with a sport-specific implement affects motor imagery

PubMed Central

Zhu, Hua; Shen, Cheng; Zhang, Jian

2018-01-01

The present study tested whether sport-specific implements facilitate motor imagery, whereas nonspecific implements disrupt motor imagery. We asked a group of basketball players (experts) and a group of healthy controls (novices) to physically perform (motor execution) and mentally simulate (motor imagery) basketball throws. Subjects produced motor imagery when they were holding a basketball, a volleyball, or nothing. Motor imagery performance was measured by temporal congruence, which is the correspondence between imagery and execution times estimated as (imagery time minus execution time) divided by (imagery time plus execution time), as well as the vividness of motor imagery. Results showed that experts produced greater temporal congruence and vividness of kinesthetic imagery while holding a basketball compared to when they were holding nothing, suggesting a facilitation effect from sport-specific implements. In contrast, experts produced lower temporal congruence and vividness of kinesthetic imagery while holding a volleyball compared to when they were holding nothing, suggesting the interference effect of nonspecific implements. Furthermore, we found a negative correlation between temporal congruence and the vividness of kinesthetic imagery in experts while holding a basketball. On the contrary, the implement manipulation did not modulate the temporal congruence of novices. Our findings suggest that motor representation in experts is built on motor experience associated with specific-implement use and thus was subjected to modulation of the implement held. We conclude that sport-specific implements facilitate motor imagery, whereas nonspecific implements could disrupt motor representation in experts. PMID:29719738

Peptidomics and Secretomics of the Mammalian Peripheral Sensory-Motor System

NASA Astrophysics Data System (ADS)

Tillmaand, Emily G.; Yang, Ning; Kindt, Callie A. C.; Romanova, Elena V.; Rubakhin, Stanislav S.; Sweedler, Jonathan V.

2015-12-01

The dorsal root ganglion (DRG) and its anatomically and functionally associated spinal nerve and ventral and dorsal roots are important components of the peripheral sensory-motor system in mammals. The cells within these structures use a number of peptides as intercellular signaling molecules. We performed a variety of mass spectrometry (MS)-based characterizations of peptides contained within and secreted from these structures, and from isolated and cultured DRG cells. Liquid chromatography-Fourier transform MS was utilized in DRG and nerve peptidome analysis. In total, 2724 peptides from 296 proteins were identified in tissue extracts. Neuropeptides are among those detected, including calcitonin gene-related peptide I, little SAAS, and known hemoglobin-derived peptides. Solid phase extraction combined with direct matrix-assisted laser desorption/ionization time-of-flight MS was employed to investigate the secretome of these structures. A number of peptides were detected in the releasate from semi-intact preparations of DRGs and associated nerves, including neurofilament- and myelin basic protein-related peptides. A smaller set of analytes was observed in releasates from cultured DRG neurons. The peptide signals observed in the releasates have been mass-matched to those characterized and identified in homogenates of entire DRGs and associated nerves. This data aids our understanding of the chemical composition of the mammalian peripheral sensory-motor system, which is involved in key physiological functions such as nociception, thermoreception, itch sensation, and proprioception.

Peptidomics and Secretomics of the Mammalian Peripheral Sensory-Motor System.

PubMed

Tillmaand, Emily G; Yang, Ning; Kindt, Callie A C; Romanova, Elena V; Rubakhin, Stanislav S; Sweedler, Jonathan V

2015-12-01

The dorsal root ganglion (DRG) and its anatomically and functionally associated spinal nerve and ventral and dorsal roots are important components of the peripheral sensory-motor system in mammals. The cells within these structures use a number of peptides as intercellular signaling molecules. We performed a variety of mass spectrometry (MS)-based characterizations of peptides contained within and secreted from these structures, and from isolated and cultured DRG cells. Liquid chromatography-Fourier transform MS was utilized in DRG and nerve peptidome analysis. In total, 2724 peptides from 296 proteins were identified in tissue extracts. Neuropeptides are among those detected, including calcitonin gene-related peptide I, little SAAS, and known hemoglobin-derived peptides. Solid phase extraction combined with direct matrix-assisted laser desorption/ionization time-of-flight MS was employed to investigate the secretome of these structures. A number of peptides were detected in the releasate from semi-intact preparations of DRGs and associated nerves, including neurofilament- and myelin basic protein-related peptides. A smaller set of analytes was observed in releasates from cultured DRG neurons. The peptide signals observed in the releasates have been mass-matched to those characterized and identified in homogenates of entire DRGs and associated nerves. This data aids our understanding of the chemical composition of the mammalian peripheral sensory-motor system, which is involved in key physiological functions such as nociception, thermoreception, itch sensation, and proprioception.

Oral-Motor and Motor-Speech Characteristics of Children with Autism.

ERIC Educational Resources Information Center

Adams, Lynn

1998-01-01

This study compared the oral-motor and motor-speech characteristics of four young children with autism and four nonautistic children. Three tasks requiring oral motor movements, simple syllable productions, and complex syllable productions were utilized. Significant differences were found in scores on the oral-motor movements and the…

A positive association between active lifestyle and hemispheric lateralization for motor control and learning in older adults.

PubMed

Wang, Jinsung; D'Amato, Arthur; Bambrough, Jennifer; Swartz, Ann M; Miller, Nora E

2016-11-01

Physical activity (PA) is well known to have general health benefits for older adults, but it is unclear whether it can also positively affect brain function involved in motor control and learning. We have previously shown that interlimb transfer of visuomotor adaptation occurs asymmetrically in young adults, while that occurs symmetrically in older adults, which suggests that the lateralized function of each hemisphere during motor tasks is diminished with aging. Here, we investigated the association between the level of PA and hemispheric motor lateralization by comparing the pattern of interlimb transfer following visuomotor adaptation between physically active and inactive older adults. Subjects were divided into two groups based on their PA level (active, inactive). They were further divided into two groups, such that a half of the subjects in each group adapted to a 30° rotation during targeted reaching movements with the left arm first, then with the right arm; and the other half with the right arm first, then with the left arm. Results indicated asymmetrical transfer (from left to right only) in the active subjects, whereas symmetrical transfer (from left to right, and vice versa) was observed in the inactive subjects. These findings suggest that older adults who maintain active lifestyle have a central nervous system that is more intact in terms of its lateralized motor function as compared with those who are inactive. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantitative measurement of intact alpha-synuclein proteoforms from post-mortem control and Parkinson's disease brain tissue by intact protein mass spectrometry.

PubMed

Kellie, John F; Higgs, Richard E; Ryder, John W; Major, Anthony; Beach, Thomas G; Adler, Charles H; Merchant, Kalpana; Knierman, Michael D

2014-07-23

A robust top down proteomics method is presented for profiling alpha-synuclein species from autopsied human frontal cortex brain tissue from Parkinson's cases and controls. The method was used to test the hypothesis that pathology associated brain tissue will have a different profile of post-translationally modified alpha-synuclein than the control samples. Validation of the sample processing steps, mass spectrometry based measurements, and data processing steps were performed. The intact protein quantitation method features extraction and integration of m/z data from each charge state of a detected alpha-synuclein species and fitting of the data to a simple linear model which accounts for concentration and charge state variability. The quantitation method was validated with serial dilutions of intact protein standards. Using the method on the human brain samples, several previously unreported modifications in alpha-synuclein were identified. Low levels of phosphorylated alpha synuclein were detected in brain tissue fractions enriched for Lewy body pathology and were marginally significant between PD cases and controls (p = 0.03).

Global forest loss disproportionately erodes biodiversity in intact landscapes.

PubMed

Betts, Matthew G; Wolf, Christopher; Ripple, William J; Phalan, Ben; Millers, Kimberley A; Duarte, Adam; Butchart, Stuart H M; Levi, Taal

2017-07-27

Global biodiversity loss is a critical environmental crisis, yet the lack of spatial data on biodiversity threats has hindered conservation strategies. Theory predicts that abrupt biodiversity declines are most likely to occur when habitat availability is reduced to very low levels in the landscape (10-30%). Alternatively, recent evidence indicates that biodiversity is best conserved by minimizing human intrusion into intact and relatively unfragmented landscapes. Here we use recently available forest loss data to test deforestation effects on International Union for Conservation of Nature Red List categories of extinction risk for 19,432 vertebrate species worldwide. As expected, deforestation substantially increased the odds of a species being listed as threatened, undergoing recent upgrading to a higher threat category and exhibiting declining populations. More importantly, we show that these risks were disproportionately high in relatively intact landscapes; even minimal deforestation has had severe consequences for vertebrate biodiversity. We found little support for the alternative hypothesis that forest loss is most detrimental in already fragmented landscapes. Spatial analysis revealed high-risk hot spots in Borneo, the central Amazon and the Congo Basin. In these regions, our model predicts that 121-219 species will become threatened under current rates of forest loss over the next 30 years. Given that only 17.9% of these high-risk areas are formally protected and only 8.9% have strict protection, new large-scale conservation efforts to protect intact forests are necessary to slow deforestation rates and to avert a new wave of global extinctions.

Ambient ionisation mass spectrometry for in situ analysis of intact proteins

PubMed Central

Kocurek, Klaudia I.; Griffiths, Rian L.

2018-01-01

Abstract Ambient surface mass spectrometry is an emerging field which shows great promise for the analysis of biomolecules directly from their biological substrate. In this article, we describe ambient ionisation mass spectrometry techniques for the in situ analysis of intact proteins. As a broad approach, the analysis of intact proteins offers unique advantages for the determination of primary sequence variations and posttranslational modifications, as well as interrogation of tertiary and quaternary structure and protein‐protein/ligand interactions. In situ analysis of intact proteins offers the potential to couple these advantages with information relating to their biological environment, for example, their spatial distributions within healthy and diseased tissues. Here, we describe the techniques most commonly applied to in situ protein analysis (liquid extraction surface analysis, continuous flow liquid microjunction surface sampling, nano desorption electrospray ionisation, and desorption electrospray ionisation), their advantages, and limitations and describe their applications to date. We also discuss the incorporation of ion mobility spectrometry techniques (high field asymmetric waveform ion mobility spectrometry and travelling wave ion mobility spectrometry) into ambient workflows. Finally, future directions for the field are discussed. PMID:29607564

Body condition and habitat use by Hermann's tortoises in burnt and intact habitats

PubMed Central

Lecq, S.; Ballouard, J.-M.; Caron, S.; Livoreil, B.; Seynaeve, V.; Matthieu, L.-A.; Bonnet, X.

2014-01-01

In Mediterranean regions, fires threaten terrestrial tortoises. Nevertheless, varying proportions of adults survive fire; these surviving individuals can play a central role for population recovery. The regions devastated by fire often include important habitat of Hermann's tortoises (Testudo hermanni hermanni), so assessing the ability of survivors to persist is essential for conserving the species. Body-condition indices provide an integrative estimate of how well individuals cope with environmental variations and impacts, including fires. Between 2002 and 2009, we monitored Hermann's tortoises in intact and burnt habitats in southeastern France. In summer 2003, a strong fire ravaged half of the surveyed zone, providing an opportunity to compare body condition of tortoises between intact and burnt areas over time. Six years later, the impact of fire on vegetation was still marked; large trees were abundant in the intact area, whereas open shrub vegetation prevailed in the burnt area. In both areas, the mean body condition of tortoises fluctuated over time; however, there were no differences between the two areas. A radio-tracking experiment demonstrated that individuals from each area were residents, and not vagrants commuting between areas. We also assessed changes in body condition and microhabitat use in radio-tracked individuals. We found no significant differences between the tortoises living in the burnt and intact areas, despite subtle differences in habitat use. In conclusion: (i) surviving tortoises in an area ravaged by fire can maintain their body condition like individuals living in an intact area, and thus, individuals from burnt areas should not be translocated to supposedly better areas; and (ii) depopulated burnt areas are likely to be appropriate for population-augmentation programmes. PMID:27293640

Effect of exercise and exogenous glucocorticoid on serum level of intact parathyroid hormone.

PubMed

Tsai, K S; Lin, J C; Chen, C K; Cheng, W C; Yang, C H

1997-11-01

Most previous studies suggest that physical exercise, or physiological response to exercise such as cortisol and adrenaline secretion regulate parathyroid hormone (PTH) secretion in humans. To investigate the effects and possible interaction of exercise and excessive glucocorticoid on PTH secretion, we examined the serum of levels of intact-PTH, cortisol, adrenocorticotrophic hormone (ACTH), calcium, magnesium and phosphorus before and during one-hour of bicycle-ergometric exercise at 60% of maximal oxygen uptake. These exercise tests were performed on eight Chinese male volunteers aged between 20 and 25 years, once with and once without pretreatment with 0.5 mg of dexamethasone taken orally 9.5 hours in advance. The results showed that dexamethasone pretreatment significantly lowered basal levels of cortisol and ACTH, but intact PTH did not change. After 60 minutes of bicycling, intact PTH level increases by 50% of baseline both with and without dexamethasone pretreatment. Serum levels of calcium, corrected for changes in serum albumin concentration, phosphorus and magnesium also increased in both cases. This study demonstrated an increase of intact-PTH with exercise which was not associated with hypocalcemia or hypomagnesemia, and was not altered in the presence of mild exogenous glucocorticoid excess and suppressed endogenous cortisol secretion.

Method for assessing motor insulation on operating motors

DOEpatents

Kueck, J.D.; Otaduy, P.J.

1997-03-18

A method for monitoring the condition of electrical-motor-driven devices is disclosed. The method is achieved by monitoring electrical variables associated with the functioning of an operating motor, applying these electrical variables to a three phase equivalent circuit and determining non-symmetrical faults in the operating motor based upon symmetrical components analysis techniques. 15 figs.

Remembering forward: Neural correlates of memory and prediction in human motor adaptation

PubMed Central

Scheidt, Robert A; Zimbelman, Janice L; Salowitz, Nicole M G; Suminski, Aaron J; Mosier, Kristine M; Houk, James; Simo, Lucia

2011-01-01

We used functional MR imaging (FMRI), a robotic manipulandum and systems identification techniques to examine neural correlates of predictive compensation for spring-like loads during goal-directed wrist movements in neurologically-intact humans. Although load changed unpredictably from one trial to the next, subjects nevertheless used sensorimotor memories from recent movements to predict and compensate upcoming loads. Prediction enabled subjects to adapt performance so that the task was accomplished with minimum effort. Population analyses of functional images revealed a distributed, bilateral network of cortical and subcortical activity supporting predictive load compensation during visual target capture. Cortical regions - including prefrontal, parietal and hippocampal cortices - exhibited trial-by-trial fluctuations in BOLD signal consistent with the storage and recall of sensorimotor memories or “states” important for spatial working memory. Bilateral activations in associative regions of the striatum demonstrated temporal correlation with the magnitude of kinematic performance error (a signal that could drive reward-optimizing reinforcement learning and the prospective scaling of previously learned motor programs). BOLD signal correlations with load prediction were observed in the cerebellar cortex and red nuclei (consistent with the idea that these structures generate adaptive fusimotor signals facilitating cancellation of expected proprioceptive feedback, as required for conditional feedback adjustments to ongoing motor commands and feedback error learning). Analysis of single subject images revealed that predictive activity was at least as likely to be observed in more than one of these neural systems as in just one. We conclude therefore that motor adaptation is mediated by predictive compensations supported by multiple, distributed, cortical and subcortical structures. PMID:21840405

Intact parathyroid hormone and whole parathyroid hormone assay results disagree in hemodialysis patients under cinacalcet hydrochloride therapy.

PubMed

Koda, Ryo; Kazama, Junichiro James; Matsuo, Koji; Kawamura, Kazuko; Yamamoto, Suguru; Wakasugi, Minako; Takeda, Tetsuro; Narita, Ichiei

2015-08-01

The parathyroid gland secretes 1-84 and 7-84 parathyroid hormone (PTH) fragments, and its regulation is dependent on stimulation of the extracellular calcium-sensing receptor. While the intact PTH system detects both PTH fragments, the whole PTH system detects the 1-84PTH but not the 7-84PTH. Cinacalcet hydrochloride (CH) binds to calcium-sensing receptor as a calcimimetic. Here we investigated the role of CH treatment in the assessment of parathyroid gland function. Stable adult dialysis patients for whom CH therapy was planned were included. Patients for whom CH therapy was not planned were simultaneously included as the control group. The CH group (n = 44) showed significantly higher circulating levels of Ca, intact PTH, and whole PTH, before the CH treatment than the control group (n = 112). The Ca, intact PTH, and whole PTH levels decreased along with the CH therapy, and the Ca levels became comparable in the 8th week of treatment and thereafter. The CH group in the 8th week and thereafter showed significantly lower whole/intact PTH ratios than the control group, while the whole/intact PTH ratio was not significantly different between before and during the CH therapy. A multiple regression analysis revealed that the whole/intact PTH ratio was almost constant, but both the serum Ca level and a CH therapy could potentially modify the fixed number. When the whole PTH levels were estimated by intact PTH levels using the relationship between them in the control group, the levels were clearly overestimated in the CH group. Although the direct effect of CH on the whole/intact PTH ratio is masked by its hypocalcemic action, we could successfully demonstrate that the ratio in CH users is lower than that in the non-users with comparable levels of serum Ca. Evaluating parathyroid function with intact PTH according to the clinical practice guidelines in patients being treated with CH may lead to significant overestimation and subsequent overtreatment.

Plasmid AZOBR_p1-borne fabG gene for putative 3-oxoacyl-[acyl-carrier protein] reductase is essential for proper assembly and work of the dual flagellar system in the alphaproteobacterium Azospirillum brasilense Sp245.

PubMed

Filip'echeva, Yulia A; Shelud'ko, Andrei V; Prilipov, Alexei G; Burygin, Gennady L; Telesheva, Elizaveta M; Yevstigneyeva, Stella S; Chernyshova, Marina P; Petrova, Lilia P; Katsy, Elena I

2018-02-01

Azospirillum brasilense can swim and swarm owing to the activity of a constitutive polar flagellum (Fla) and inducible lateral flagella (Laf), respectively. Experimental data on the regulation of the Fla and Laf assembly in azospirilla are scarce. Here, the coding sequence (CDS) AZOBR_p1160043 (fabG1) for a putative 3-oxoacyl-[acyl-carrier protein (ACP)] reductase was found essential for the construction of both types of flagella. In an immotile leaky Fla - Laf - fabG1::Omegon-Km mutant, Sp245.1610, defects in flagellation and motility were fully complemented by expressing the CDS AZOBR_p1160043 from plasmid pRK415. When pRK415 with the cloned CDS AZOBR_p1160045 (fliC) for a putative 65.2 kDa Sp245 Fla flagellin was transferred into the Sp245.1610 cells, the bacteria also became able to assemble a motile single flagellum. Some cells, however, had unusual swimming behavior, probably because of the side location of the organelle. Although the assembly of Laf was not restored in Sp245.1610 (pRK415-p1160045), this strain was somewhat capable of swarming motility. We propose that the putative 3-oxoacyl-[ACP] reductase encoded by the CDS AZOBR_p1160043 plays a role in correct flagellar location in the cell envelope and (or) in flagellar modification(s), which are also required for the inducible construction of Laf and for proper swimming and swarming motility of A. brasilense Sp245.

Motor cortex is required for learning but not executing a motor skill

PubMed Central

Kawai, Risa; Markman, Timothy; Poddar, Rajesh; Ko, Raymond; Fantana, Antoniu; Dhawale, Ashesh; Kampff, Adam R.; Ölveczky, Bence P.

2018-01-01

Motor cortex is widely believed to underlie the acquisition and execution of motor skills, yet its contributions to these processes are not fully understood. One reason is that studies on motor skills often conflate motor cortex’s established role in dexterous control with roles in learning and producing task-specific motor sequences. To dissociate these aspects, we developed a motor task for rats that trains spatiotemporally precise movement patterns without requirements for dexterity. Remarkably, motor cortex lesions had no discernible effect on the acquired skills, which were expressed in their distinct pre-lesion forms on the very first day of post-lesion training. Motor cortex lesions prior to training, however, rendered rats unable to acquire the stereotyped motor sequences required for the task. These results suggest a remarkable capacity of subcortical motor circuits to execute learned skills and a previously unappreciated role for motor cortex in ‘tutoring’ these circuits during learning. PMID:25892304

Coupling with concentric contact around motor shaft for line start synchronous motor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melfi, Michael J.; Burdeshaw, Galen E.

A method comprises providing a line-start synchronous motor. The motor has a stator, a rotor core disposed within the stator, and a motor shaft. In accordance with a step of the method, a coupling for coupling a load to the motor is provided. The coupling has a motor shaft attachment portion configured to provide substantially concentric contact around the shaft at the end of the motor shaft. The coupling has a load attachment portion configured to operatively connect to a load. In accordance with a step of the method, a load is coupled to the motor with the coupling, andmore » driven from start to at least near synchronous speed during steady state operation of the motor with a load coupled thereto. The motor shaft attachment portion may comprise a bushing assembly with matching and opposed tapered surfaces that cooperate to secure the motor shaft attachment portion around the motor shaft.« less

Biomechanics and symmetry

NASA Astrophysics Data System (ADS)

Ott, Albrecht

2004-04-01

Molecular motors are of nm scale they are the smallest motors known. They are quasi-omnipresent in the biological organism and among their most promiment functions are muscle contraction, flagellar motion, intracellular transport and cellular motion. In most cases the "fuel" for these motors is provided by the cleavage of a molecule named adenosinetri-phosphate (ATP) to its diphosphate (ADP). How this chemically stored energy is transformed into motion, although a subject of major research all over the world, is only partly understood. Motor function is a dynamical problem, and no technique today is capable of monitoring dynamics at nm scale. The energies involved are close to thermal, making a good signal to noise ratio difficult to achieve. Last not not least, a great deal of knowledge is needed to understand the multiple facets of this problem, ranging from biochemistry, nm technology to theoretical physics.

Motor cortex inhibition

PubMed Central

Isaacs, K.M.; Augusta, M.; MacNeil, L.K.; Mostofsky, S.H.

2011-01-01

Objective: Attention-deficit/hyperactivity disorder (ADHD) is a childhood-onset behavioral diagnosis in which children often fail to meet age norms in development of motor control, particularly timed repetitive and sequential movements, motor overflow, and balance. The neural substrate of this motor delay may include mechanisms of synaptic inhibition in or adjacent to the motor cortex. The primary objective of this study was to determine whether transcranial magnetic stimulation (TMS)–evoked measures, particularly short interval cortical inhibition (SICI), in motor cortex correlate with the presence and severity of ADHD in childhood as well as with commonly observed delays in motor control. Methods: In this case-control study, behavioral ratings, motor skills, and motor cortex physiology were evaluated in 49 children with ADHD (mean age 10.6 years, 30 boys) and 49 typically developing children (mean age 10.5 years, 30 boys), all right-handed, aged 8–12 years. Motor skills were evaluated with the Physical and Neurological Examination for Subtle Signs (PANESS) and the Motor Assessment Battery for Children version 2. SICI and other physiologic measures were obtained using TMS in the left motor cortex. Results: In children with ADHD, mean SICI was reduced by 40% (p < 0.0001) and less SICI correlated with higher ADHD severity (r = −0.52; p = 0.002). Mean PANESS motor development scores were 59% worse in children with ADHD (p < 0.0001). Worse PANESS scores correlated modestly with less SICI (r = −.30; p = 0.01). Conclusion: Reduced TMS-evoked SICI correlates with ADHD diagnosis and symptom severity and also reflects motor skill development in children. PMID:21321335

Dor procedure for pulmonary atresia with intact ventricular septum in an infant.

PubMed

Kang, Yoonjin; Kwak, Jae Gun; Kim, Eung Rae; Kim, Woong-Han

2018-02-01

Pulmonary atresia with intact ventricular septum and right ventricle-dependent coronary circulation confers a high risk for myocardial infarction and complications of ischaemia, including left ventricle aneurysms. We describe an infant with pulmonary atresia with intact ventricular septum and right ventricle-dependent coronary circulation and a left ventricle apical aneurysm who successfully underwent the Dor procedure and a subsequent Fontan operation. Surgery for postinfarction left ventricle aneurysm can be considered in infants. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Role of CheW protein in coupling membrane receptors to the intracellular signaling system of bacterial chemotaxis.

PubMed Central

Liu, J D; Parkinson, J S

1989-01-01

Chemotactic behavior in Escherichia coli is mediated by membrane-associated chemoreceptors that transmit sensory signals to the flagellar motors through an intracellular signaling system, which appears to involve a protein phosphorylation cascade. This study concerns the role of CheW, a cytoplasmic protein, in coupling methyl-accepting chemotaxis proteins (MCPs), the major class of membrane receptors, to the intracellular signaling system. Steady-state flagellar rotation behavior was examined in a series of strains with different combinations and relative amounts of CheW, MCPs, and other signaling components. At normal expression levels, CheW stimulated clockwise rotation, and receptors appeared to enhance this stimulatory effect. At high expression levels, MCPs inhibited clockwise rotation, and CheW appeared to augment this inhibitory effect. Since overexpression of CheW or MCP molecules had the same behavioral effect as their absence, chemoreceptors probably use CheW to modulate two distinct signals, one that stimulates and one that inhibits the intracellular phosphorylation cascade. Images PMID:2682657

Motor Controller System For Large Dynamic Range of Motor Operation

NASA Technical Reports Server (NTRS)

Howard, David E. (Inventor); Alhorn, Dean C. (Inventor); Smith, Dennis A. (Inventor); Dutton, Kenneth R. (Inventor); Paulson, Mitchell Scott (Inventor)

2006-01-01

A motor controller system uses a rotary sensor with a plurality of signal conditioning units, coupled to the rotary sensor. Each of these units, which is associated with a particular range of motor output shaft rotation rates, generate a feedback signal indicative of the position of the motor s output shaft. A controller (i) converts a selected motor output shaft rotation rate to a corresponding incremental amount of rotational movement for a selected fixed time period, (ii) selects, at periodic completions of the selected fixed time period, the feedback signal from one of the signal conditioning units for which the particular range of motor output shaft rotation rates associated therewith encompasses the selected motor output shaft rotation rate, and (iii) generates a motor drive signal based on a difference between the incremental amount of rotational movement and the feedback signal from the selected one of the signal conditioning Units.

Collateral development and spinal motor reorganization after nerve injury and repair

PubMed Central

Yu, Youlai; Zhang, Peixun; Han, Na; Kou, Yuhui; Yin, Xiaofeng; Jiang, Baoguo

2016-01-01

Functional recovery is often unsatisfactory after severe extended nerve defects or proximal nerve trunks injuries repaired by traditional repair methods, as the long regeneration distance for the regenerated axons to reinnervate their original target end-organs. The proximal nerve stump can regenerate with many collaterals that reinnervate the distal stump after peripheral nerve injury, it may be possible to use nearby fewer nerve fibers to repair more nerve fibers at the distal end to shorten the regenerating distance. In this study, the proximal peroneal nerve was used to repair both the distal peroneal and tibial nerve. The number and location of motor neurons in spinal cord as well as functional and morphological recovery were assessed at 2 months, 4 months and 8 months after nerve repair, respectively. Projections from the intact peroneal and tibial nerves were also studied in normal animals. The changes of motor neurons were assessed using the retrograde neurotracers FG and DiI to backlabel motor neurons that regenerate axons into two different pathways. To evaluate the functional recovery, the muscle forces and sciatic function index were examined. The muscles and myelinated axons were assessed using electrophysiology and histology. The results showed that all labeled motor neurons after nerve repair were always confined within the normal peroneal nerve pool and nearly all the distribution of motor neurons labeled via distal different nerves was disorganized as compared to normal group. However, there was a significant decline in the number of double labeled motor neurons and an obvious improvement with respect to the functional and morphological recovery between 2 and 8 months. In addition, the tibial/peroneal motor neuron number ratio at different times was 2.11±0.05, 2.13±0.08, 2.09±0.12, respectively, and was close to normal group (2.21±0.09). Quantitative analysis showed no significant morphological differences between myelinated nerve fibers

Solitary chemoreceptor cell survival is independent of intact trigeminal innervation.

PubMed

Gulbransen, Brian; Silver, Wayne; Finger, Thomas E

2008-05-01

Nasal solitary chemoreceptor cells (SCCs) are a population of specialized chemosensory epithelial cells presumed to broaden trigeminal chemoreceptivity in mammals (Finger et al. [2003] Proc Natl Acad Sci USA 100:8981-8986). SCCs are innervated by peptidergic trigeminal nerve fibers (Finger et al. [2003]) but it is currently unknown if intact innervation is necessary for SCC development or survival. We tested the dependence of SCCs on innervation by eliminating trigeminal nerve fibers during development with neurogenin-1 knockout mice, during early postnatal development with capsaicin desensitization, and during adulthood with trigeminal lesioning. Our results demonstrate that elimination of innervation at any of these times does not result in decreased SCC numbers. In conclusion, neither SCC development nor mature cell maintenance is dependent on intact trigeminal innervation. (c) 2008 Wiley-Liss, Inc.

Directed flux motor

NASA Technical Reports Server (NTRS)

Wilson, Andrew (Inventor); Punnoose, Andrew (Inventor); Strausser, Katherine (Inventor); Parikh, Neil (Inventor)

2011-01-01

A directed flux motor described utilizes the directed magnetic flux of at least one magnet through ferrous material to drive different planetary gear sets to achieve capabilities in six actuated shafts that are grouped three to a side of the motor. The flux motor also utilizes an interwoven magnet configuration which reduces the overall size of the motor. The motor allows for simple changes to modify the torque to speed ratio of the gearing contained within the motor as well as simple configurations for any number of output shafts up to six. The changes allow for improved manufacturability and reliability within the design.