Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Locomotion

  • bipedal locomotion
  • cell locomotion
  • high-speed locomotion
  • quadrupedal locomotion
  • terrestrial locomotion

  • Terms modified by Locomotion

  • locomotion behaviour
  • locomotion control

  • Selected Abstracts

    Locomotion and Escape Modes in Rodents of the Monte Desert (Argentina)

    ETHOLOGY, Issue 6 2003
    Paula Taraborelli
    Modes of locomotion and escape tactics are attributes that affect the structure of animal communities, promoting exploitation of different microhabitats and the coexistence of different species. Bipedal locomotion is considered to be more effective than a quadrupedal gait in escaping attacks by predators because it allows for higher speed, a faster response to attack, sudden changes of direction and better detection of aerial raptors. The aim of this study was to determine the type of locomotion used at the moment of escape by three rodent species of the Monte desert ,Eligmodontia typus, Akodon molinae and Graomys griseoflavus. The study was carried out in three plant communities of the Ñacuñán Reserve (Mendoza). All three species showed differences in both mode of escape and locomotory pattern. Graomys griseoflavus exhibited the highest proportion of escapes using quadrupedal saltation. The mode of locomotion employed by E. typus varied according to the type of plant communities it inhabited. Those occurring at open sites (Medanal community) exhibited a greater propensity to jump during escapes than those from more sheltered habitats (Algarrobal community). Akodon molinae relied primarily on a quadrupedal gait when fleeing from predators, which would explain its greater dependence on plant cover. Therefore, the morphological and behavioural characteristics of these species are related to their mode of locomotion and the strategies they employ to diminish the risk of predation. [source]

    Effects of Ultraviolet Radiation on Locomotion and Orientation in Roughskin Newts (Taricha granulosa)

    ETHOLOGY, Issue 3 2000
    Andrew R. Blaustein
    Environmental changes, including those associated with the atmosphere may significantly affect individual animals and ultimately populations. Ultraviolet (UV) radiation, perhaps increasing due to stratospheric ozone depletion, has been linked to mortality in a number of organisms, including amphibians. The eggs and larvae of certain amphibian species hatch at significantly lower rates when exposed to ambient ultraviolet light. Yet little is known about the sublethal effects of UV radiation. For example, UV radiation may affect specific behaviors of an animal that could alter its ability to survive. To examine if UV radiation affects amphibian behavior, we used roughskin newts (Taricha granulosa) as a model. Newts were exposed to low-level doses of UV in the laboratory and then tested in the field to examine if UV-exposed and control (no UV) newts differed in orientation towards water or in locomotor activity levels. UV-exposed and control newts both exhibited a significant orientation towards water in field tests but there was no significant difference in orientation between treatments. However, UV-exposed newts were significantly more active than control newts. Our results suggest that exposure to short-term low levels of UV radiation alters certain behaviors. Environmentally induced changes in behavior may have significant ecological and evolutionary consequences. [source]

    The generation of rhythmic activity in dissociated cultures of rat spinal cord

    Jürg Streit
    Abstract Locomotion in vertebrates is controlled by central pattern generators in the spinal cord. The roles of specific network architecture and neuronal properties in rhythm generation by such spinal networks are not fully understood. We have used multisite recording from dissociated cultures of embryonic rat spinal cord grown on multielectrode arrays to investigate the patterns of spontaneous activity in randomised spinal networks. We were able to induce similar patterns of rhythmic activity in dissociated cultures as in slice cultures, although not with the same reliability and not always with the same protocols. The most reliable rhythmic activity was induced when a partial disinhibition of the network was combined with an increase in neuronal excitability, suggesting that both recurrent synaptic excitation and neuronal excitability contribute to rhythmogenesis. During rhythmic activity, bursts started at several sites and propagated in variable ways. However, the predominant propagation patterns were independent of the protocol used to induce rhythmic activity. When synaptic transmission was blocked by CNQX, APV, strychnine and bicuculline, asynchronous low-rate activity persisted at ,,50% of the electrodes and ,,70% of the sites of burst initiation. Following the bursts, the activity in the interval was transiently suppressed below the level of intrinsic activity. The degree of suppression was proportional to the amount of activity in the preceding burst. From these findings we conclude that rhythmic activity in spinal cultures is controlled by the interplay of intrinsic neuronal activity and recurrent excitation in neuronal networks without the need for a specific architecture. [source]

    Many Roads Lead to Rome: Locomotion and Dynamics

    INFANCY, Issue 2 2000
    Esther Thelen
    First page of article [source]

    Magnetic-Field-Induced Locomotion of Glass Fibers on Water Surfaces: Towards the Understanding of How Much Force One Magnetic Nanoparticle Can Deliver

    ADVANCED MATERIALS, Issue 19 2009
    Feng Shi
    The amount of force one magnetic nanoparticle (MNPs) can deliver is calculated using Fe3O4 MNPs building blocks to modify glass fibers. Our results demonstrate that one weight unit of Fe3O4 MNPs can eventually drag ,10,000 times its own weight on a water surface, a significant finding for the development of new magnetic delivery systems and micromanipulators. [source]

    Mechatronic Design and Locomotion of Amoebot,A Metamorphic Underwater Vehicle

    I-Ming Chen
    The Metamorphic Underwater Vehicle (MUV) is a vehicle that propels in the water by continuously changing the shape of its body similar to the motion of the microorganism amoebae. In this article, we describe the basic design of Amoebot, a plastic MUV that achieves shape-changing capability through the inflation and deflation of water-filled balloons. A sequence of inflation and deflation procedures can be taken to produce cyclic swimming shapes that propel the MUV. Swimming shapes similar to the microorganism amoebae have been successfully reproduced by present Amoebot. The mechanical system designed proves to be very reliable and flexible in producing desired body shapes. The physical shape of the Amoebot is analyzed numerically and its variation in time during the swim can be expressed explicitly. By formulating sets of idealized swimming rules based on the changing shape, simulations are carried out to predict the trajectory and study the pseudo dynamics of the swimming of Amoebot. Possible applications of this type of underwater vehicle are discussed. © 2003 Wiley Periodicals, Inc. [source]

    A possible evolutionary pathway to insect flight starting from lepismatid organization

    Starting from the hypothesis that flight in Pterygota evolved from lepismatid organization of their ancestors, the functional anatomy of the thorax was studied in Lepisma saccharina Linnaeus, 1758, and a Ctenolepisma sp. in regard to both the adaptations to the adaptive zone of Lepismatidae and to pre-adaptations for the evolution of Pterygota. Well-preserved parts of three subcoxal leg segments were found in the pleural zone participating in leg movement. The lepismatid strategy of escaping predators by running fast and hiding in narrow flat retreats led to a dorso-ventrally flattened body which enabled gliding effects when dropped, followed by flight on the ground. The presumed exploitation of soft tissue at the tips of low growing Devonian vascular plants opened a canalized pathway to the evolution of the flying ability. Locomotion to another plant was facilitated by dropping. It is possible that threat by spider-like predators favoured falling and gliding as escape reactions by selection. Falling experiments with `lepismatid' models revealed a narrow `window' for gliding, with optimum dimensions of 8 mm body length and 8 mg weight. An equation was derived which describes the glide distance as function of weight, area of the horizontal outline, the specific glide efficiency of the body, and a non-linear function of the falling height. Improved gliding was made possible by enlarging thoracic paratergites into broad wing-like extensions of light-weight organization. The disadvantage of the lateral lobes for locomotion on the ground could be minimized by tilting them vertically when running and horizontally when gliding. This movability could be attained by the intercalation of a membranous strip between tergite and paratergite and the utilization of the pre-existing muscular system and the articulation between the two most basal subcoxal sclerites as a pivot. The dorsal part of the most basal subcoxa was thus integrated into the wing. Initiation of active flight was possible by flapping movements during gliding. Morphological, ontogenetic and ecological aspects of the origin of Pterygota are discussed. Ein möglicher, von der lepismatiden Organisation ausgehender Evolütionsweg zum Flugvermögen der Insekten Ausgehend von der Hypothese daß die Evolution des Flugvermögens der Pterygota mit der lepismatiden Organisation ihrer Ahnen begann, wurde die funktionelle Anatomie des Thorax von Lepisma saccharina und einer Ctenolepisma sp. im Hinblick auf Adaptationen an die adaptive Zone der Lepismatidae und im Hinblick auf Praeadaptationen für die Evolution der Pterygota untersucht. Es wurden in der Pleuralzone gut erhaltene Teile von drei subcoxalen Beingliedern gefunden, die an der Beinbewegung teilnehmen. Die Strategie der Lepismatidae, vor Feinden durch rasches Laufen zu fliehen und sich in flachen Spalten zu verstecken, führte zu einer dorsoventralen Abflachung des Körpers, die beim Herabfallen Gleiteffekte und weitere Flucht am Boden ermöglichte. Im Zusammenhang mit der vermuteten Ernährung von Triebspitzen der im Devon noch niedrigen Gefäßpflanzen eröffnete dies einen kanalisierten Evolutionsweg zum aktiven Flug wobei möglicherweise spinnenartige Prädatoren den Selektionsdruck verstärkten. Gleitversuche mit `lepismatiden' Modellen zeigten ein enges Gleitfenster mit dem Optimum von 8 mg Gewicht und 8 mm Körperlänge. Es wurde eine Gleichung gefunden, die die Gleitdistanz als Funktion der Gleitfläche, der Masse, der Gleiteffizienz des Fallkörpers und einer nicht-linearen Funktion der Fallhöhe beschreibt. Vergrößerung der Gleitdistanz war möglich, wenn die Körpermasse veringert, die lateral vorragenden thorakalen Paratergite vergrößert wurden und als `Flügel' nicht länger als breit waren. Die Behinderung der Flucht am Boden durch laterale `Flügel' konnte durch deren Vertikalstellung beim Laufen und durch Horizontalstellung beim Gleiten vermindert werden. Die Beweglichkeit war durch Einfügen eines Membranstreifens zwischen Tergit und Paratergit sowie die Nutzung des vorhandenen Gelenks zwischen zwei basalen Subcoxalgliedern mit dem vorhandenen Muskelsystem möglich. Demnach ist der dorsale Teil eines ursprünglichen Beingliedes im Flügel der Pterygota integriert. Auf- und Abbewegung der Flügel während des Gleitens ermöglichten den Beginn des aktiven Fluges. Die dafür erforderlichen Transformationen sowie deren ontogenetische und ökologische Aspekte werden diskutiert. [source]

    Upward mobility and alternative lifestyles: a report from the 10th biennial meeting on Bacterial Locomotion and Signal Transduction

    Birgit E. Scharf
    Summary This past January, in Cuernavaca Mexico, a conglomerate of scientists met to discuss the contemporary view of Bacterial Locomotion and Signal Transduction (BLAST). The BLAST meetings represent a field that has its roots in chemotaxis and the flagellum-based motility but now encompass all types of cellular movement and signalling. The topics varied from the interactions between molecules to the interactions between species. We heard about 3D reconstructions of transmembrane chemoreceptors within cells, new biophysical methods for understanding cellular engines, intricate phosphorelays, elaborate gene networks, new messenger molecules and emerging behaviours within complex populations of cells. At BLAST X we gained an appreciation for the lifestyle choices bacteria make, how they get to where they are going and the molecular mechanisms that underlie their decisions. Herein we review the highlights of the meeting. [source]

    Variation and context of yawns in captive chimpanzees (Pan troglodytes)

    Sarah-Jane Vick
    Abstract Primate yawns are usually categorized according to context (e.g. as a threat, anxious, or rest yawn), but there has been little consideration of whether these yawns are best regarded as a unitary behavior that only differs with respect to the context in which it is observed. This study examined the context and precise morphology of yawns in a group of 11 captive chimpanzees. Focal video sampling was used to describe the morphology and intensity of 124 yawns using ChimpFACS, a system for coding facial movements. Two distinct forms of yawn were identified, a full yawn and a yawn which is modified by additional actions that reduce the mouth aperture. These modified yawns may indicate some degree of voluntary control over facial movement in chimpanzees and, consequently, multiple functions of yawning according to context. To assess context effects, mean activity levels (resting, locomotion, and grooming) and scratching rates were compared one minute before and after each yawn. Locomotion was significantly increased following both types of yawn, whereas scratching rates significantly increased following modified yawns but decreased following full yawns. In terms of individual differences, males did not yawn more than females, although male yawns were of higher intensity, both in the degree of mouth opening and in the amount of associated head movement. These data indicate that yawning is associated with a change in activity levels in chimpanzees, but only modified yawns may be related to increased arousal. Different types of yawn can therefore be differentiated at the morphological level as well as context level. Am. J. Primatol. 72:262,269, 2010. © 2009 Wiley-Liss, Inc. [source]

    Rail, Steam, and Speed: The "Rocket" and the Birth of Steam Locomotion , By Christopher McGowan

    THE HISTORIAN, Issue 4 2008
    Marsh Wilkinson Jones
    No abstract is available for this article. [source]

    Magnetoresponsive Microparticles with Nanoscopic Surface Structures for Remote-Controlled Locomotion,

    ANGEWANDTE CHEMIE, Issue 22 2010
    Shin-Hyun Kim Dr.
    Kügelchen in Bewegung: Die Rotations- und Translationsbewegung magnetischer Janus-Partikel mit nanoskopischer Oberflächenstruktur kann durch ein externes Magnetfeld gesteuert werden (siehe Bild). Die nanoskopischen Oberflächenmuster verstärken die mikroskopische Bewegung der Mikrokügelchen, indem sie eine starke Kopplung zwischen Rotation und Translation induzieren. Es ist außerdem möglich, einzelne Mikrokügelchen aus dem Gemisch abzutrennen. [source]

    Morphological correlates of burst speed and field movement patterns: the behavioural adjustment of locomotion in wall lizards (Podarcis muralis)

    Locomotion of lizards has clear morphological determinants and is important for developing activities such as feeding, social interaction and predator avoidance. Thus, morphological variation is believed to have fitness consequences through affecting locomotor performance. This paper firstly evaluates the dependence of burst speed on morphology, and secondly examines the movement patterns of free-ranging undisturbed wall lizards (Podarcis muralis) engaged in several kinds of activity. Body size was the most important correlate of burst speed as performed at the optimal temperature for running in the laboratory. After removing size effects from performance and morphological traits, the length of some particular limb segments had positive influence on burst speed, but these effects were weak, each trait explaining less than 16% of variance in burst speed. Free-ranging P. muralis exhibited intermittent locomotion, with movement sequences interrupted by frequent short pauses. Field movement patterns greatly differed depending upon the kind of activity and were in most aspects independent of the size and sex of the animal. P. muralis involved in thermoregulation performed short and low-speed displacements; exploratory activities were characterized by frequent, slow and short movements. On the contrary, lizards involved in intraspecific pursuits and predator escape developed comparatively high speeds, although only exceptionally did they attain the size-specific burst speed predicted from the laboratory trials. Speed of escape increased with distance to the refuge and the animals are able to assess predation risks to modulate approach distance, speed and pauses, so maximum exertion is seldom required. The evolution of locomotor capacities exceeding routine needs is discussed in the context of the principle of ,excessive construction'. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society, 2003, 80, 135,146. [source]

    Ascertaining the prevalence of childhood disability

    T. Hutchison
    Abstract Objectives, To reapply 1985 Office of Population Census and Surveys (OPCS) disability survey methods, modified as necessary, to a sample of children to ascertain presence of disability. To compare OPCS-based prevalence with prevalence based on carer's views and medical records. Design, Analytical study. Setting, Community Child Health Department in UK. Participants, Principal carers of 100 children aged 5,15, selected from a district special needs register. Main outcome measures, Comparable information about disability from three sources and diagnosis from carers and medical records. Results, Medical records of 46% contained a diagnosis. Carers were always aware of this, although a single question did not always elicit their knowledge. OPCS-derived threshold disability criteria in categories of Hand function, Personal care, Consciousness and Continence gave prevalence results similar to medical records and carers. OPCS criteria yielded higher prevalence of disability in the areas of Locomotion (8%), Communication (14%) and Hearing (18%). Carers, OPCS and medical records disagreed markedly about prevalence of disabilities of Vision, probably because of the use of differing definitions. OPCS learning criteria were judged unsuitable and standard attainment targets (SATs) were substituted. These provided similar prevalence figures to carers and medical records. OPCS behaviour criteria were also unsuitable and were replaced by the General Health and Behaviour Questionnaire (GHBQ). This found an increased prevalence of problems compared with carers and doctors. Conclusions, Diagnostic labels have limited use when collecting data about disabled children. Doubt is cast on the validity of some of the 1985 OPCS threshold criteria, and reassessment is suggested before their future use. Further work is needed on the use of SATs and GHBQ in the benchmarking of disability. To collect population data it would be easier and at least equally effective (with caution in the case of Vision) to ask carers directly rather than applying descriptive thresholds and external judgements. Similar information could be obtained from medical records, however, they are likely to be out of date. [source]

    Interactive animation of virtual humans based on motion capture data

    Franck Multon
    Abstract This paper presents a novel, parameteric framework for synthesizing new character motions from existing motion capture data. Our framework can conduct morphological adaptation as well as kinematic and physically-based corrections. All these solvers are organized in layers in order to be easily combined together. Given locomotion as an example, the system automatically adapts the motion data to the size of the synthetic figure and to its environment; the character will correctly step over complex ground shapes and counteract with external forces applied to the body. Our framework is based on a frame-based solver. This ensures animating hundreds of humanoids with different morphologies in real-time. It is particularly suitable for interactive applications such as video games and virtual reality where a user interacts in an unpredictable way. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Real-time locomotion control by sensing gloves

    Taku Komura
    Abstract Sensing gloves are often used as an input device for virtual 3D games. We propose a new method to control characters such as humans or animals in real-time by using sensing gloves. Based on existing motion data of the body, a new method to map the hand motion of the user to the locomotion of 3D characters in real-time is proposed. The method was applied to control locomotion of characters such as humans or dogs. Various motions such as trotting, running, hopping, and turning could be produced. As the computational cost needed for our method is low, the response of the system is short enough to satisfy the real-time requirements that are essential to be used for games. Using our method, users can directly control their characters intuitively and precisely than previous controlling devices such as mouse, keyboards or joysticks. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    A grasp-based motion planning algorithm for character animation

    Maciej Kalisiak
    The design of autonomous characters capable of planning their own motions continues to be a challenge for computer animation. We present a novel kinematic motion-planning algorithm for character animation which addresses some of the outstanding problems. The problem domain for our algorithm is as follows: given a constrained environment with designated handholds and footholds, plan a motion through this space towards some desired goal. Our algorithm is based on a stochastic search procedure which is guided by a combination of geometric constraints, posture heuristics, and distance-to-goal metrics. The method provides a single framework for the use of multiple modes of locomotion in planning motions through these constrained, unstructured environments. We illustrate our results with demonstrations of a human character using walking, swinging, climbing, and crawling in order to navigate through various obstacle courses. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Artificial Animals and Humans: From Physics to Intelligence

    Demetri Terzopoulos
    The confluence of virtual reality and artificial life, an emerging discipline that spans the computational and biological sciences, has yielded synthetic worlds inhabited by realistic, artificial flora and fauna. Artificial animals are complex synthetic organisms that possess functional biomechanical bodies, sensors, and brains with locomotion, perception, behavior, learning, and cognition centers. Artificial humans and other animals are of interest in computer graphics because they are self-animating characters that dramatically advance the state of the art of production animation and interactive game technologies. More broadly, these biomimetic autonomous agents in their realistic virtual worlds also foster deeper, computationally oriented insights into natural living systems. [source]

    Adenosine A3 receptors regulate heart rate, motor activity and body temperature

    ACTA PHYSIOLOGICA, Issue 2 2010
    J. N. Yang
    Abstract Aim:, To examine the phenotype of mice that lack the adenosine A3 receptor (A3R). Methods:, We examined the heart rate, body temperature and locomotion continuously by telemetry over several days. In addition, the effect of the adenosine analogue R- N6 -phenylisopropyl-adenosine (R-PIA) was examined. We also examined heat production and food intake. Results:, We found that the marked diurnal variation in activity, heart rate and body temperature, with markedly higher values at night than during day time, was reduced in the A3R knock-out mice. Surprisingly, the reduction in heart rate, activity and body temperature seen after injection of R-PIA in wild type mice was virtually eliminated in the A3R knock-out mice. The marked reduction in activity was associated with a decreased heat production, as expected. However, the A3R knock-out mice, surprisingly, had a higher food intake but no difference in body weight compared to wild type mice. Conclusions:, The mice lacking adenosine A3 receptors exhibit a surprisingly clear phenotype with changes in diurnal rhythm and temperature regulation. Whether these effects are due to a physiological role of A3 receptors in these processes or whether they represent a role in development remains to be elucidated. [source]

    The role of inhibitory neurotransmission in locomotor circuits of the developing mammalian spinal cord

    ACTA PHYSIOLOGICA, Issue 2 2009
    H. Nishimaru
    Abstract Neuronal circuits generating the basic coordinated limb movements during walking of terrestrial mammals are localized in the spinal cord. In these neuronal circuits, called central pattern generators (CPGs), inhibitory synaptic transmission plays a crucial part. Inhibitory synaptic transmission mediated by glycine and GABA is thought to be essential in coordinated activation of muscles during locomotion, in particular, controlling temporal and spatial activation patterns of muscles of each joint of each limb on the left and right side of the body. Inhibition is involved in other aspects of locomotion such as control of speed and stability of the rhythm. However, the precise roles of neurotransmitters and their receptors mediating inhibitory synaptic transmission in mammalian spinal CPGs remain unclear. Moreover, many of the inhibitory interneurones essential for output pattern of the CPG are yet to be identified. In this review, recent advances on these issues, mainly from studies in the developing rodent spinal cord utilizing electrophysiology, molecular and genetic approaches are discussed. [source]

    Caveolin-1 polarization in migrating endothelial cells is directed by substrate topology not chemoattractant gradient

    CYTOSKELETON, Issue 11 2006
    Virginie Santilman
    Abstract Polarization is a hallmark of migrating cells, and an asymmetric distribution of proteins is essential to the migration process. Caveolin-1 is highly polarized in migrating endothelial cells (EC). Several studies have shown caveolin-1 accumulation in the front of migrating EC while others report its accumulation in the EC rear. In this paper we address these conflicting results on polarized localization of caveolin-1. We find evidence for the hypothesis that different modes of locomotion lead to differences in protein polarization. In particular, we show that caveolin-1 is primarily localized in the rear of cells migrating on a planar substrate, but in the front of cells traversing a three-dimensional pore. We also show that a chemoattractant, present either as a gradient or ubiquitously in the medium, does not alter caveolin-1 localization in cells in either mode of locomotion. Thus we conclude that substrate topology, and not the presence of a chemoattractant, directs the polarization of caveolin-1 in motile ECs. Cell Motil. Cytoskeleton 2006. © 2006 Wiley-Liss, Inc. [source]

    Preparing to move: Assembly of the MSP amoeboid motility apparatus during spermiogenesis in Ascaris

    CYTOSKELETON, Issue 4 2005
    Maria Antonia Rodriguez
    Abstract We exploited the rapid, inducible conversion of non-motile Ascaris spermatids into crawling spermatozoa to examine the pattern of assembly of the MSP motility apparatus that powers sperm locomotion. In live sperm, the first detectable motile activity is the extension of spikes and, later, blebs from the cell surface. However, examination of cells by EM revealed that the formation of surface protrusions is preceded by assembly of MSP filament tails on the membranous organelles in the peripheral cytoplasm. These organelle-associated filament meshworks assemble within 30 sec after induction of spermiogenesis and persist until the membranous organelles are sequestered into the cell body when the lamellipod extends. The filopodia-like spikes, which are packed with bundles of filaments, extend and retract rapidly but last only a few seconds before giving way to, or converting into, blebs. Coalescence of these blebs, each supported by a dense mesh of filaments, often initiates lamellipod extension, which culminates in the formation of the robust, dynamic MSP fiber complexes that generate sperm motility. The same membrane phosphoprotein that orchestrates assembly of the fiber complexes at the leading edge of the lamellipod of mature sperm is also found at all sites of filament assembly during spermiogenesis. The orderly progression of steps that leads to construction of a functional motility apparatus illustrates the precise spatio-temporal control of MSP filament assembly in the developing cell and highlights the remarkable similarity in organization and plasticity shared by the MSP cytoskeleton and the actin filament arrays in conventional crawling cells. Cell Motil. Cytoskeleton 60:191,199, 2005 © 2005 Wiley-Liss, Inc. [source]

    The motility of glioblastoma tumour cells is modulated by intracellular cofilin expression in a concentration-dependent manner

    CYTOSKELETON, Issue 3 2005
    Celestial T. Yap
    Abstract The invasive behaviour of tumour cells has been attributed in part to dysregulated cell motility. Members of the ADF/Cofilin family of actin-binding proteins are known to increase microfilament dynamics by increasing the rate at which actin monomers leave the pointed end of the filament and by a filament-severing activity. As depolymerisation is a rate-limiting step in actin dynamics, ADF/Cofilins are suspected to facilitate the motility of cells. To test this, we investigated the influence of cofilin on tumour motility by transient and stably overexpressing cofilin in the human glioblastoma cell line, U373 MG. Several different methods were used to ascertain the level of cofilin in overexpressing clones and this was correlated with their rate of random locomotion. A biphasic relationship between cofilin level and locomotory rate was found. Clones that displayed a moderate amount of overproduction of cofilin were found to have increased rates of locomotion approximately linear to the overproduction of cofilin up to an optimal cofilin level of about 4.5 times that of wild type cells at which the cells were almost twice as fast. However, clones producing more than this optimal amount were found to locomote at progressively reduced speeds. Cells that overexpress cofilin have reduced stress fibres compared to control cells showing that the excess cofilin affects the actin cytoskeleton. We conclude that overexpression of cofilin enhances the motility of glioblastoma tumour cells in a concentration-dependent fashion, which is likely to contribute to their invasiveness. Cell Motil. Cytoskeleton 60:153,165, 2005. © 2005 Wiley-Liss, Inc. [source]

    Gliding movement in Peranema trichophorum is powered by flagellar surface motility

    CYTOSKELETON, Issue 4 2003
    Akira Saito
    Abstract A colorless euglenoid flagellate Peranema trichophorum shows unique unidirectional gliding cell locomotion on the substratum at velocities up to 30 ,m/s by an as yet unexplained mechanism. In this study, we found that (1) treatment with NiCl2 inhibited flagellar beating without any effect on gliding movement; (2) water currents applied to a gliding cell from opposite sides caused detachment of the cell body from the substratum. With only the anterior flagellum adhering to the substratum, gliding movement continued along the direction of the anterior flagellum; (3) gentle pipetting induced flagellar severance into various lengths. In these cells, gliding velocity was proportional to the flagellar length; and (4) Polystyrene beads were translocated along the surface of the anterior flagellum. All of these results indicate that a cell surface motility system is present on the anterior flagellum, which is responsible for cell gliding in P. trichophorum. Cell Motil. Cytoskeleton 55:244,253, 2003. © 2003 Wiley-Liss, Inc. [source]

    Gastrin-Releasing Peptide, a Bombesin-like Neuropeptide, Promotes Cutaneous Wound Healing

    Yuji Yamaguchi MD
    Background. Little is known about the effects of neuropeptides on wound healing. Objective. To investigate the effect of gastrin-releasing peptide (GRP), one of the bombesin-like neuropeptides, on wound healing. Methods. The effects of GRP on cultured keratinocyte proliferation and migration were measured by BrdU uptake and in vitro scratch assay, respectively. Various concentrations of GRP ointments (0, 10,9, 10,8, 10,7, 10,6 M) were topically applied to 1.0 mm wounds on porcine flanks. Results. GRP stimulated keratinocyte growth and locomotion in a dose-dependent manner. Topical administration of GRP accelerated macroscopic epidermal regeneration in a dose-dependent manner, as measured by planimetry. Histologic studies also showed that GRP promoted reepithelialization, including epidermal thickness as well as superficial skin coverage. conclusion. Topical use of GRP may clinically accelerate wound healing of burns, injuries, chronic ulcers, and skin graft donor sites through the enhancement of keratinocyte growth and spreading. [source]

    Adults with cerebral palsy: a survey describing problems, needs, and resources, with special emphasis on locomotion

    Christina Andersson MSc PT
    The purpose of this study was to describe problems and resources of adults with cerebral palsy (CP) with special emphasis on locomotion. A questionnaire concerning demographic facts, locomotion, musculoskeletal problems, and present physical activity was mailed to 363 adults with CP. Two hundred and twenty-one adults, (125 male and 96 female; mean age 36 years, range 20 to 58 years) answered the questionnaire. Seventy-seven per cent reported problems with spasticity. Eighty-four per cent lived in their own apartments, with or without home services. Twenty-four per cent worked full-time and 18% had full disability pension. Twenty-seven per cent had never been able to walk, 64% could walk with or without walking aids, 35% reported decreased walking ability, and 9% had stopped walking. Eighty per cent reported contractures and 18% had pain every day. Approximately 60% were regularly physically active, and despite their disability, 54% considered that they were not limited in their ability to move about in the community. [source]

    Glutamate drives the touch response through a rostral loop in the spinal cord of zebrafish embryos

    Thomas Pietri
    Abstract Characterizing connectivity in the spinal cord of zebrafish embryos is not only prerequisite to understanding the development of locomotion, but is also necessary for maximizing the potential of genetic studies of circuit formation in this model system. During their first day of development, zebrafish embryos show two simple motor behaviors. First, they coil their trunks spontaneously, and a few hours later they start responding to touch with contralateral coils. These behaviors are contemporaneous until spontaneous coils become infrequent by 30 h. Glutamatergic neurons are distributed throughout the embryonic spinal cord, but their contribution to these early motor behaviors in immature zebrafish is still unclear. We demonstrate that the kinetics of spontaneous coiling and touch-evoked responses show distinct developmental time courses and that the touch response is dependent on AMPA-type glutamate receptor activation. Transection experiments suggest that the circuits required for touch-evoked responses are confined to the spinal cord and that only the most rostral part of the spinal cord is sufficient for triggering the full response. This rostral sensory connection is presumably established via CoPA interneurons, as they project to the rostral spinal cord. Electrophysiological analysis demonstrates that these neurons receive short latency AMPA-type glutamatergic inputs in response to ipsilateral tactile stimuli. We conclude that touch responses in early embryonic zebrafish arise only after glutamatergic synapses connect sensory neurons and interneurons to the contralateral motor network via a rostral loop. This helps define an elementary circuit that is modified by the addition of sensory inputs, resulting in behavioral transformation. © 2009 Wiley Periodicals, Inc. Develop Neurobiol 2009 [source]

    Drosophila cdk5 is needed for locomotive behavior and NMJ elaboration, but seems dispensable for synaptic transmission

    Alexander E. Kissler
    Abstract Cyclin-dependent kinase 5 (Cdk5) functions in postmitotic neuronal cells and play roles in cell differentiation, cell migration, axonal guidance, and synaptic function. Here, we demonstrate that Drosophila cdk5 is dispensable for adult viability and fertility, a feature that allows us to study its physiological function in the whole animal model. For the adult, cdk5 is needed for proper locomotion and flight performance. Larvae lacking cdk5 in the presynaptic tissue display abnormal crawling motion, and their neuromuscular junctions (NMJ) are elongated and contain a higher number of boutons that are smaller. As a result of these two counteracting effects, the total synaptic area/NMJ is similar to wild type, leading to normal synaptic transmission, indicating that a compensatory mechanism is capable of correcting the problem caused by the lack of cdk5. futsch, the Drosophila MAP1B homolog, is also involved in NMJ morphogenesis, and analysis of the NMJ phenotype of the double mutant futschK68; cdk5, indicates that cdk5 is epistatic to futsch in this process. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009 [source]

    Hox genes and the regulation of movement in Drosophila

    Richa Dixit
    Abstract Many animals show regionally specialized patterns of movement along the body axis. In vertebrates, spinal networks regulate locomotion, while the brainstem controls movements of respiration and feeding. Similarly, amongst invertebrates diversification of appendages along the body axis is tied to the performance of characteristically different movements such as those required for feeding, locomotion, and respiration. Such movements require locally specialized networks of nerves and muscles. Here we use the regionally differentiated movements of larval crawling in Drosophila to investigate how the formation of a locally specialized locomotor network is genetically determined. By loss and gain of function experiments we show that particular Hox gene functions are necessary and sufficient to dictate the formation of a neuromuscular network that orchestrates the movements of peristaltic locomotion. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2008 [source]

    Disruption of insulin pathways alters trehalose level and abolishes sexual dimorphism in locomotor activity in Drosophila

    Yesser Hadj Belgacem
    Abstract Insulin signaling pathways are implicated in several physiological processes in invertebrates, including the control of growth and life span; the latter of these has also been correlated with juvenile hormone (JH) deficiency. In turn, JH levels have been correlated with sex-specific differences in locomotor activity. Here, the involvement of the insulin signaling pathway in sex-specific differences in locomotor activity was investigated in Drosophila. Ablation of insulin-producing neurons in the adult pars-intercerebralis was found to increase trehalosemia and to abolish sexual dimorphism relevant to locomotion. Conversely, hyper-insulinemia induced by insulin injection or by over-expression of an insulin-like peptide decreases trehalosemia but does not affect locomotive behavior. Moreover, we also show that in the head of adult flies, the insulin receptor (InR) is expressed only in the fat body surrounding the brain. While both male and female InR mutants are hyper-trehalosemic, they exhibit similar patterns of locomotor activity. Our results indicate that first, insulin controls trehalosemia in adults, and second, like JH, it controls sex-specific differences in the locomotor activity of adult Drosophila in a manner independent of its effect on trehalose metabolism. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2006 [source]

    Regulation of neuronal excitability in Drosophila by constitutively active CaMKII

    Demian Park
    Abstract The ability of calcium/calmodulin-dependent protein kinase II (CaMKII) to become calcium independent after autophosphorylation makes this enzyme a temporal marker of neuronal activity. Here we show that the calcium-independent form of CaMKII has unique effects on larval viability, locomotion, and neuronal excitability in Drosophila. Expression of constitutively active T287D, but not calcium-dependent T287A, mutant CaMKII in Drosophila neurons resulted in decreased viability, behavioral defects, and failure of action potential propagation. The actions of T287D may be mediated, at least in part, by increased potassium conductances. Expression of T287D CaMKII also stimulated an increase in the number of boutons at the larval neuromuscular junction, but did not affect the mechanics of release. This study defines a role for autophosphorylation of CaMKII in the regulation of multiple neuronal functions including the intrinsic properties of neurons. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 24,42, 2002 [source]