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Mark J Alkema - One of the best experts on this subject based on the ideXlab platform.
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a tyramine gated chloride channel coordinates distinct motor programs of a caenorhabditis elegans Escape Response
Neuron, 2009Co-Authors: Jennifer K. Pirri, Adam D. Mcpherson, Jamie L. Donnelly, Michael M. Francis, Mark J AlkemaAbstract:Summary A key feature of Escape Responses is the fast translation of sensory information into a coordinated motor output. In C. elegans , anterior touch initiates a backward Escape Response in which lateral head movements are suppressed. Here, we show that tyramine inhibits head movements and forward locomotion through the activation of a tyramine-gated chloride channel, LGC-55. lgc-55 mutant animals have defects in reversal behavior and fail to suppress head oscillations in Response to anterior touch. lgc-55 is expressed in neurons and muscle cells that receive direct synaptic inputs from tyraminergic motor neurons. Therefore, tyramine can act as a classical inhibitory neurotransmitter. Activation of LGC-55 by tyramine coordinates the output of two distinct motor programs, locomotion and head movements that are critical for a C. elegans Escape Response.
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A Tyramine-Gated Chloride Channel Coordinates Distinct Motor Programs of a Caenorhabditis elegans Escape Response
Neuron, 2009Co-Authors: Jennifer K. Pirri, Adam D. Mcpherson, Jamie L. Donnelly, Michael M. Francis, Mark J AlkemaAbstract:A key feature of Escape Responses is the fast translation of sensory information into a coordinated motor output. In C. elegans, anterior touch initiates a backward Escape Response in which lateral head movements are suppressed. Here, we show that tyramine inhibits head movements and forward locomotion through the activation of a tyramine-gated chloride channel, LGC-55. lgc-55 mutant animals have defects in reversal behavior and fail to suppress head oscillations in Response to anterior touch. lgc-55 is expressed in neurons and muscle cells that receive direct synaptic inputs from tyraminergic motor neurons. Therefore, tyramine can act as a classical inhibitory neurotransmitter. Activation of LGC-55 by tyramine coordinates the output of two distinct motor programs, locomotion and head movements that are critical for a C. elegans Escape Response. © 2009 Elsevier Inc. All rights reserved.
George V Lauder - One of the best experts on this subject based on the ideXlab platform.
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Hydrodynamics of C-Start Escape Responses of Fish as Studied with Simple Physical Models
Integrative and Comparative Biology, 2015Co-Authors: William C. Witt, George V LauderAbstract:: One of the most-studied unsteady locomotor behaviors exhibited by fishes is the c-start Escape Response. Although the kinematics of these Responses have been studied extensively and two well-defined kinematic stages have been documented, only a few studies have focused on hydrodynamic patterns generated by fishes executing Escape behaviors. Previous work has shown that Escape Responses by bluegill sunfish generate three distinct vortex rings, each with central orthogonal jet flows, and here we extend this conclusion to two other species: stickleback and mosquitofish. Jet #1 is formed by the tail during Stage 1, and moves in the same direction as Stage-2 movement of the fish, thereby reducing final Escape-velocity but also rotating the fish. Jet #2, in contrast, moves approximately opposite to the final direction of the fish's motion and contains the bulk of the total fluid-momentum powering the Escape Response. Jet #3 forms during Stage 2 in the mid-body region and moves in a direction approximately perpendicular to jets 1 and 2, across the direction of movement of the body. In this study, we used a mechanical controller to impulsively move passively flexible plastic panels of three different stiffnesses in heave, pitch, and heave + pitch motions to study the effects of stiffness on unsteady hydrodynamics of Escape. We were able to produce kinematics very similar to those of fish c-starts and also to reproduce the 3-jet hydrodynamic pattern of the c-start using a panel of medium flexural stiffness and the combined heave + pitch motion. This medium-stiffness panel matched the measured stiffness of the near-tail region of fish bodies. This motion also produced positive power when the panel straightened during stage 2 of the Escape Response. More flexible and stiffer panels resulted in non-biological kinematics and patterns of flow for all motions. The use of simple flexible models with a mechanical controller and program of fish-like motion is a promising approach for studying unsteady behaviors of fish which can be difficult to manipulate experimentally in live animals.
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median fin function during the Escape Response of bluegill sunfish lepomis macrochirus ii fin ray curvature
The Journal of Experimental Biology, 2012Co-Authors: Brad A Chadwell, George V Lauder, Emily M Standen, Miriam A AshleyrossAbstract:Although kinematic analysis of individual fin rays provides valuable insight into the contribution of median fins to C-start performance, it paints an incomplete picture of the complex movements and deformation of the flexible fin surface. To expand our analysis of median fin function during the Escape Response of bluegill sunfish ( Lepomis macrochirus ), patterns of spanwise and chordwise curvature of the soft dorsal and anal fin surfaces were examined from the same video sequences previously used in analysis of fin-ray movement and orientation. We found that both the span and chord undergo undulation, starting in the anterior region of either fin. Initiated early in Stage 1 of the C-start, the undulation travels in a postero-distal direction, reaching the trailing edge of the fins during early Stage 2. Maximum spanwise curvature typically occurred among the more flexible posterior fin rays, though there was no consistent correlation between maximum curvature and fin-ray position. Undulatory patterns suggest different mechanisms of action for the fin regions. In the anterior fin region, where the fin rays are oriented dorsoventrally, undulation is directed primarily chordwise, initiating a transfer of momentum into the water to overcome the inertia of the flow and direct the water posteriorly. Within the posterior region, where the fin rays are oriented caudally, undulation is predominantly directed spanwise; thus, the posterior fin region acts to ultimately accelerate this water towards the tail to increase thrust forces. Treatment of median fins as appendages with uniform properties does not do justice to their complexity and effectiveness as control surfaces. * LIST OF SYMBOLS AND ABBREVIATIONS : ARy# : anal ray, where # indicates its numbered position within the fin ASp# : anal spine, where # indicates its numbered position within the fin C : chord axis of the fin surface, perpendicular to the span axis cT : tangent to the chordwise curve DRy# : dorsal ray, where # indicates its numbered position within the fin DSp# : dorsal spine, where # indicates its numbered position within the fin EMG : electromyography L : lateral axis, normal to the fin surface Mid : middle trunk r : fin-ray identifier S : span axis of the fin surface S1 : stage 1 of the C-start S2 : stage 2 of the C-start sB : binormal to the fin surface sfA : soft region of the anal fin sfD : soft dorsal fin ssCOM : stretched-straight center of mass sT : tangent to the spanwise curve t : time point during a C-start sequence T : time zero tr : directional transition event, i.e. change in direction of rotation or orientation t X : time of a given parameter, where X is the event of a given parameter Δ t X : time difference between a given fin-ray parameter and its corresponding axial event, where X is the event of a given parameter κchord : chordwise curvature, perpendicular to the fin surface and span axis κspan : spanwise curvature, perpendicular to the fin surface ϕ′ : turning rate, i.e. the first time derivative of yaw
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median fin function during the Escape Response of bluegill sunfish lepomis macrochirus i fin ray orientation and movement
The Journal of Experimental Biology, 2012Co-Authors: Brad A Chadwell, George V Lauder, Emily M Standen, Miriam A AshleyrossAbstract:The fast-start Escape Response is critically important to avoid predation, and axial movements driving it have been studied intensively. Large median dorsal and anal fins located near the tail have been hypothesized to increase acceleration away from the threat, yet the contribution of flexible median fins remains undescribed. To investigate the role of median fins, C-start Escape Responses of bluegill sunfish ( Lepomis macrochirus ) were recorded by three high-speed, high-resolution cameras at 500 frames s−1 and the 3-D kinematics of individual dorsal and anal fin rays were analyzed. Movement and orientation of the fin rays relative to the body axis were calculated throughout the duration of the C-start. We found that: (1) timing and magnitude of angular displacement varied among fin rays based on position within the fin and (2) kinematic patterns support the prediction that fin rays are actively resisting hydrodynamic forces and transmitting momentum into the water. We suggest that regions within the fins have different roles. Anterior regions of the fins are rapidly elevated to increase the volume of water that the fish may interact with and transmit force into, thus generating greater total momentum. The movement pattern of all the fin rays creates traveling waves that move posteriorly along the length of the fin, moving water as they do so. Flexible posterior regions ultimately act to accelerate this water towards the tail, potentially interacting with vortices generated by the caudal fin during the C-start. Despite their simple appearance, median fins are highly complex and versatile control surfaces that modulate locomotor performance. * a : acceleration of the ssCOM parallel to the fish trajectory A 〈 x 〉 : area, where x represents the fin surface between a named fin-ray and the next posterior digitized fin ray, or of the entire named fin/region Ant : anterior trunk ARy# : anal rays, where # indicates its numbered position within the fin ASp# : anal spines, where # indicates its numbered position within the fin C : chord axis of the fin surface cT : tangent to the chordwise curve D : displacement of the center of mass DRy# : dorsal rays, where # indicates its numbered position within the fin DSp# : dorsal spines, where # indicates its numbered position within the fin Fr : frontal axis, a.k.a. normal to the frontal plane L : lateral axis, a.k.a. normal to the fin surface Mid : middle trunk MSE : mean square error Op : operculum Post : posterior trunk r : fin-ray identifier Rs : rostrum S : span axis of the fin surface S1 : stage 1 of the C-start S2 : stage 2 of the C-start Seg : body segment identifier sfA : soft region of the anal fin sfD : soft dorsal fin Sg : sagittal axis, a.k.a. normal to the sagittal plane spD : spiny dorsal fin ssCOM : stretched-straight center of mass sT : tangent to the spanwise curve t : time point during a C-start sequence T : time zero TL : total length tr directional transition event, i.e. change in direction of rotation or orientation Tr : transverse axis, a.k.a. normal to the transverse plane t X : time of a given parameter, where X is the event of a given parameter v : velocity of the ssCOM parallel to the fish trajectory ![Graphic][1] : average span axis angle of a fin ray Δ t X : time difference between a given fin-ray parameter and its corresponding axial event, where X is the event of a given parameter ![Graphic][2] : average elevation of a fin ray θ′ : turning rate, i.e. the first time derivative of yaw ![Graphic][3] : average sweep angle of a fin ray [1]: /embed/inline-graphic-168.gif [2]: /embed/inline-graphic-169.gif [3]: /embed/inline-graphic-170.gif
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hydrodynamics of the Escape Response in bluegill sunfish lepomis macrochirus
The Journal of Experimental Biology, 2008Co-Authors: Eric D Tytell, George V LauderAbstract:SUMMARY Escape Responses of fishes are one of the best characterized vertebrate behaviors, with extensive previous research on both the neural control and biomechanics of startle Response performance. However, very little is known about the hydrodynamics of Escape Responses, despite the fact that understanding fluid flow patterns during the Escape is critical for evaluating how body movement transfers power to the fluid, for defining the time course of power generation, and for characterizing the wake signature left by escaping fishes, which may provide information to predators. In this paper, we present an experimental hydrodynamic analysis of the C-start Escape Response in bluegill sunfish ( Lepomis macrochirus ). We used time-resolved digital particle image velocimetry at 1000 frames s –1 (fps) to image flow patterns during the Escape Response. We analyzed flow patterns generated by the body separately from those generated by the dorsal and anal fins to assess the contribution of these median fins to Escape momentum. Each Escape Response produced three distinct jets of fluid. Summing the components of fluid momentum in the jets provided an estimate of fish momentum that did not differ significantly from momentum measured from the escaping fish body. In contrast to conclusions drawn from previous kinematic analyses and theoretical models, the caudal fin generated momentum that opposes the Escape during stage one, whereas the body bending during stage one contributed substantial propulsive momentum. Additionally, the dorsal and anal fins each contributed substantial momentum. The results underscore the importance of the dorsal and anal fins as propulsors and suggest that the size and placement of these fins may be a key determinant of fast start performance.
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the c start Escape Response of polypterus senegalus bilateral muscle activity and variation during stage 1 and 2
The Journal of Experimental Biology, 2002Co-Authors: Eric D Tytell, George V LauderAbstract:The fast-start Escape Response is the primary reflexive Escape mechanism in a wide phylogenetic range of fishes. To add detail to previously reported novel muscle activity patterns during the Escape Response of the bichir, Polypterus, we analyzed Escape kinematics and muscle activity patterns in Polypterus senegalus using high-speed video and electromyography (EMG). Five fish were filmed at 250 Hz while synchronously recording white muscle activity at five sites on both sides of the body simultaneously (10 sites in total). Body wave speed and center of mass velocity, acceleration and curvature were calculated from digitized outlines. Six EMG variables per channel were also measured to characterize the motor pattern. P. senegalus shows a wide range of activity patterns, from very strong Responses, in which the head often touched the tail, to very weak Responses. This variation in strength is significantly correlated with the stimulus and is mechanically driven by changes in stage 1 muscle activity duration. Besides these changes in duration, the stage 1 muscle activity is unusual because it has strong bilateral activity, although the observed contralateral activity is significantly weaker and shorter in duration than ipsilateral activity. Bilateral activity may stiffen the body, but it does so by a constant amount over the variation we observed; therefore, P. senegalus does not modulate fast-start wave speed by changing body stiffness. Escape Responses almost always have stage 2 contralateral muscle activity, often only in the anterior third of the body. The magnitude of the stage 2 activity is the primary predictor of final Escape velocity. Summary
Linda Partridge - One of the best experts on this subject based on the ideXlab platform.
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a computational model of the Escape Response latency in the giant fiber system of drosophila melanogaster
eNeuro, 2019Co-Authors: Hrvoje Augustin, Asaph Zylbertal, Linda PartridgeAbstract:Abstract The giant fiber system (GFS) is a multi-component neuronal pathway mediating rapid Escape Response in the adult fruit-fly Drosophila melanogaster, usually in the face of a threatening visual stimulus. Two branches of the circuit promote the Response by stimulating an Escape jump followed by flight initiation. A recent work demonstrated an age-associated decline in the speed of signal propagation through the circuit, measured as the stimulus-to-muscle depolarization Response latency. The decline is likely due to the diminishing number of inter-neuronal gap junctions in the GFS of ageing flies. In this work, we presented a realistic conductance-based, computational model of the GFS that recapitulates the experimental results and identifies some of the critical anatomical and physiological components governing the circuit’s Response latency. According to our model, anatomical properties of the GFS neurons have a stronger impact on the transmission than neuronal membrane conductance densities. The model provides testable predictions for the effect of experimental interventions on the circuit’s performance in young and ageing flies.
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a computational model of the Escape Response latency in the giant fiber system of drosophila melanogaster
bioRxiv, 2018Co-Authors: Hrvoje Augustin, Asaph Zylbertal, Linda PartridgeAbstract:ABSTRACT The Giant Fiber System (GFS) is a multi-component neuronal pathway mediating rapid Escape Response in the adult fruit-fly Drosophila melanogaster, usually in the face of a threatening visual stimulus. Two branches of the circuit promote the Response by stimulating an Escape jump followed by flight initiation. Our recent work demonstrated an age-associated decline in the speed of signal propagation through the circuit, measured as the stimulus-to-muscle depolarization Response latency. The decline is likely due to the diminishing number of interneuronal gap junctions in the GFS of ageing flies. In this work, we presented a realistic conductance-based, computational model of the GFS that recapitulates our experimental results and identifies some of the critical anatomical and physiological components governing the circuit’s Response latency. According to our model, anatomical properties of the GFS neurons have a stronger impact on the transmission than neuronal membrane conductance densities. The model provides testable predictions for the effect of experimental interventions on the circuit’s performance in young and ageing flies.
Jennifer K. Pirri - One of the best experts on this subject based on the ideXlab platform.
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a tyramine gated chloride channel coordinates distinct motor programs of a caenorhabditis elegans Escape Response
Neuron, 2009Co-Authors: Jennifer K. Pirri, Adam D. Mcpherson, Jamie L. Donnelly, Michael M. Francis, Mark J AlkemaAbstract:Summary A key feature of Escape Responses is the fast translation of sensory information into a coordinated motor output. In C. elegans , anterior touch initiates a backward Escape Response in which lateral head movements are suppressed. Here, we show that tyramine inhibits head movements and forward locomotion through the activation of a tyramine-gated chloride channel, LGC-55. lgc-55 mutant animals have defects in reversal behavior and fail to suppress head oscillations in Response to anterior touch. lgc-55 is expressed in neurons and muscle cells that receive direct synaptic inputs from tyraminergic motor neurons. Therefore, tyramine can act as a classical inhibitory neurotransmitter. Activation of LGC-55 by tyramine coordinates the output of two distinct motor programs, locomotion and head movements that are critical for a C. elegans Escape Response.
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A Tyramine-Gated Chloride Channel Coordinates Distinct Motor Programs of a Caenorhabditis elegans Escape Response
Neuron, 2009Co-Authors: Jennifer K. Pirri, Adam D. Mcpherson, Jamie L. Donnelly, Michael M. Francis, Mark J AlkemaAbstract:A key feature of Escape Responses is the fast translation of sensory information into a coordinated motor output. In C. elegans, anterior touch initiates a backward Escape Response in which lateral head movements are suppressed. Here, we show that tyramine inhibits head movements and forward locomotion through the activation of a tyramine-gated chloride channel, LGC-55. lgc-55 mutant animals have defects in reversal behavior and fail to suppress head oscillations in Response to anterior touch. lgc-55 is expressed in neurons and muscle cells that receive direct synaptic inputs from tyraminergic motor neurons. Therefore, tyramine can act as a classical inhibitory neurotransmitter. Activation of LGC-55 by tyramine coordinates the output of two distinct motor programs, locomotion and head movements that are critical for a C. elegans Escape Response. © 2009 Elsevier Inc. All rights reserved.
Helga Guderley - One of the best experts on this subject based on the ideXlab platform.
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Effect of different predators on the Escape Response of Placopecten magellanicus
Marine Biology, 2015Co-Authors: Helga Guderley, John H. Himmelman, Madeleine Nadeau, Hernan Pérez Cortes, Isabelle Tremblay, Xavier JanssooneAbstract:To assess whether giant scallops, Placopecten magellanicus use distinct Escape strategies to respond to their seastar and crustacean predators, Escape Responses to two major seastar predators, Asterias vulgaris and Leptasterias polaris, two seastars with little predatory impact, Crossaster papposus and Solaster endeca, and two crustacean predators, Cancer irroratus and Hyas araneus were compared. A glass rod served as a mechanical control. The Responses of juvenile [2+ year (y), ~36-mm shell height (SH)] and adult (6+ y, ~100-mm SH) scallops from the Magdalen Islands, Quebec, Canada, were assessed in early summer 2005. The predatory seastars evoked the strongest Response, in terms of both Response latency and minimum interval between phasic contractions and numbers of phasic contractions, particularly early in the Escape Response. Both the minor seastar predators and crabs stimulated stronger Responses than the mechanical control. Juvenile scallops were livelier than adult scallops. As P. magellanicus consistently responded to predators with an initial flurry of phasic contractions that tapered off to spaced phasic contractions separated by increasingly long tonic contractions, only the intensity of the Escape Response seems to have been modified by selection.
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Escape Responses by jet propulsion in scallops1
Canadian Journal of Zoology, 2013Co-Authors: Helga Guderley, Isabelle TremblayAbstract:The impressive swimming Escape Response of scallops uses a simple locomotor system that facilitates analysis of the functional relationships between its primary components. One large adductor muscle, two valves, the muscular mantle, and the rubbery hinge ligament are the basic elements allowing swimming by jet propulsion. Although these basic functional elements are shared among scallop species, the exact nature of the Escape Response varies considerably within and among species. Valve shape and density have opposing influences upon the capacity for swimming and the ease of attack by predators once captured. Patterns of muscle use can partly overcome the constraints imposed by shell characteristics. The depletion of muscle reserves during gametogenesis leads to a trade-off between Escape Response performance and reproductive investment. However, changes in muscle energetic status influence repeat performance more than initial Escape performance. Escape Response performance is influenced by habitat tempera...
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Diet and performance in the scallop, Argopecten purpuratus : force production during Escape Responses and mitochondrial oxidative capacities
Aquatic Living Resources, 2011Co-Authors: Helga Guderley, Katherina Brokordt, Hernán M. Pérez Cortés, Yanic Marty, Edouard KraffeAbstract:We examined whether Escape Response performance and mitochondrial capacities could reveal differences created by feeding scallops, Argopecten purpuratus, mono-specific algal diets composed of either Chaetoceros calcitrans or Isochrysis galbana (variety T. iso) hereafter T. iso. Before and after feeding scallops with these diets, we assessed force production in vivo to evaluate Escape Response performance (initial and repeat). We measured oxidative capacities of mitochondria isolated from the adductor muscle and from the male and female portions of the gonad. Initial Escape Response performance was reduced more by the C. calcitrans diet than by the T. iso diet. Repeat Escape Responses, which require aerobic recuperation, were reduced by both treatments. The oxidative capacity of mitochondria isolated from muscle and female gonad was markedly lower in scallops fed C. calcitrans than in those fed T. iso. Flux through complex I–IV and through complex IV was also lower in mitochondria from muscle of scallops fed C. calcitrans than in those fed T. iso. Muscle aerobic capacity, assessed by citrate synthase activity, was lower in scallops fed C. calcitrans than in those fed T. iso. Despite the marked differences in fatty acid (FA) composition of the algal diets, the FA composition of mitochondrial phospholipids differed little between scallops fed C. calcitrans and those fed T. iso. Both Escape Response behaviour and mitochondrial capacities changed with feeding mono-specific diets. The simplicity of measurements of scallop Escape Responses suggests this as a practical means of evaluating the status of scallops for the two monoalgal diets tested.
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Allozyme heterozygosity and Escape Response performance of the scallops, Argopecten purpuratus and Placopecten magellanicus
Marine Biology, 2011Co-Authors: Hernán Mauricio Pérez, Katherina Brokordt, Réjean Tremblay, Helga GuderleyAbstract:Multilocus allozyme heterozygosity (MLH) has been positively correlated with growth in some marine bivalves and was suggested to facilitate swimming activity in pectinids. Using two highly mobile scallops, Placopecten magellanicus and Argopecten purpuratus, we examined Escape Response performance and morphometric characteristics as a function of allelic variability at metabolic loci. Ten allozyme systems were used for A. purpuratus and 7 for P. magellanicus. In each species, the morphometric characteristics and Escape Response parameters were analyzed separately using principal components analysis (PCA) and the scores of the major principal components were related to allozyme heterozygosity. In both P. magellanicus and A. purpuratus, positive correlations were found between MLH and morphometric parameters, but Escape Response parameters were only positively linked to MLH in P. magellanicus, and then weakly. The hypothesis that MLH improves fitness of pectinids by increasing the capacity to Escape predators is not supported.
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Effect of reproduction on Escape Responses, metabolic rates and muscle mitochondrial properties in the scallop Placopecten magellanicus
Marine Biology, 2008Co-Authors: Edouard Kraffe, Réjean Tremblay, Yanic Marty, Sonia Belvin, Jeqn-rené Lecoz, Helga GuderleyAbstract:In scallops, gametogenesis and spawning can diminish the metabolic capacities of the adductor muscle and reduce Escape Response performance. To evaluate potential mechanisms underlying this compromise between reproductive investment and Escape Response, we examined the impact of reproductive stage (pre-spawned, spawned and reproductive quiescent) of the giant scallop, Placopecten magellanicus , on behavioural (i.e., Escape Responses), physiological (i.e., standard metabolic rates and metabolic rates after complete fatigue) and mitochondrial capacities (i.e., oxidative rates) and composition. Escape Responses changed markedly with reproductive investment, with spawned scallops making fewer claps and having shorter Responses than pre-spawned or reproductive-quiescent animals. After recuperation, spawned scallops also recovered a lower proportion of their initial Escape Response. Scallop metabolic rate after complete fatigue (VO_2max) did not vary significantly with reproductive stage whereas standard metabolic rate (VO_2min) was higher in spawned scallops. Thus spawned scallops had the highest maintenance requirements (VO_2min/VO_2max). Maximal capacities for glutamate oxidation by muscle mitochondria did not change with reproductive stage although levels of ANT and cytochromes as well as cytochrome C oxidase (CCO) activity did. Total mitochondrial phospholipids, sterols and the proportion of phospholipid classes differed only slightly between reproductive stages. Few modifications were detected in the fatty acid (FA) composition of the phospholipid classes except in cardiolipin (CL). In this class, pre-spawned and spawned scallops had fairly high proportions of 20:5n-3 whereas this FA in reproductive-quiescent scallops was threefold lower and 22:6n-3 was significantly higher. These changes paralleled the increases in CCO activity and suggest an important role of CL on the modifications of CCO activity in scallops. However, mitochondrial properties could not explain the decreased recuperation ability from exhausting exercise in spawned scallops. Shifts in maintenance requirements (VO_2min/VO_2max) and aerobic scope (VO_2max − VO_2min) provided the best explanation for the impact of reproduction on Escape Response performance.