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At least 487 records · Page 27Linked to original sources
PubMed1998

Spirochaete-like swimming mode of Campylobacter jejuni in a viscous environment.

The swimming patterns of Campylobacter jejuni in environments of low and high viscosity were examined by a video tracking method. In media of low viscosity, C. jejuni swam with an average velocity of 39.3 microm/s with frequent changes in direction. The velocity of C. jejuni increased in a medium at a little higher viscosity than that of a low viscosity buffer. In addition to this, C. jejuni showed a second increase of velocity in media of a high viscosity of about 40 centipoise. The swimming patterns at these two velocity peaks were compared. In the second peak the wild-type C. jejuni exhibited repeated back and forth swimming patterns which were more like the swimming pattern of spirochaetes than that of monotrichous bacteria. Thus C. jejuni may presumably use a different swimming mode in media of high viscosity than the original swimming mode mediated by the propelling force of the flagella. The spiral shape of this bacterium like that of spirochaetes may strongly influence its swimming ability in media of high viscosity such as the mucous layer of the intestinal tract.

Animals↗
PubMed1977

A mathematical model for counter-current multiplications in the swim-bladder.

1. A computer model for swim-bladder gas filling has been developed. Phenomenological descriptions of the Root effect (pH-dependent O2 capacity of fish haemoglobin), of the lactic acid production in the gas gland and of the geometry of the rete mirabile are incorporated in the general counter-current equations to give a comprehensive model of gas filling. 2. It is known that pH along the rete is not constant, as supposed in an earlier gas-filling model. It is also known that the Root shift reaction has a different half-time model. It is also known that the Root shift reaction has a different half-time depending on whether the haemoglobin absorbs or releases O2. These particular effects are accounted for in the present model. 3. The model gives gas filling rate and maximum swim-bladder pressure for CO2, O2 and N2. The partial pressure of these gases as well as the concentration of lactic acid and the pH along the rete are also calculated. 4. The model reproduces quite accurately experimental values for gas-filling rate in eel, together with lactic acid, CO2 and O2 concentrations measured at the rete end-points. There is also good correlation between maximum predicted stable swim-bladder pressure and maximum recorded depth for four fishes investigated (r=0-937; P=0-06). 5. The model predicts an enhancement of O2 filling rate and maximum swim-bladder pressure of at least 4 when the reaction rates of the Root shift in eel haemoglobin are 0-2 sec (Root-off) and 10 sec (Root-on), as compared to an instantaneous Root shift. 6. With a swim-bladder pressure of 1 atm and Root-shift reaction rates of equal magnitude, the po2-profile along the rete is nearly linear. When the reaction rates are such as found experimentally in eel haemoglobin, the po2 along the rete is non-linear, with a maximum of approximately 2 atm near the bladder pole of the rete. An experimental verification of this maximum will constitute a crucial test of the model. 7. The calculations show that blood flow through rete can regulate both gas-filling rate and stable swim-bladder pressure. At high pressure, the main factor limiting gas filling is loss of gas through back diffusion along the rete. 8. Maximum po2 in the swim-bladder is highly dependent upon the Root effect. If the Root effect persists up to about 100 atm, as seems to be the case blue hake, maximum po2 is more than 200 atm. When the Root effect is abolished at 10 atm, as is expected in eel, the maximum po2 drops to about 30 atm. 9. The pN2 in the bladder can reach 10-15 atm depending on blood flow, whereas PCO2 will not exceed 1 atm.

Air Sacs↗
PubMed1999

Organized cell swimming motions in Bacillus subtilis colonies: patterns of short-lived whirls and jets.

The swimming motions of cells within Bacillus subtilis colonies, as well as the associated fluid flows, were analyzed from video films produced during colony growth and expansion on wet agar surfaces. Individual cells in very wet dense populations moved at rates between 76 and 116 microm/s. Swimming cells were organized into patterns of whirls, each approximately 1,000 microm2, and jets of about 95 by 12 microm. Whirls and jets were short-lived, lasting only about 0.25 s. Patterns within given areas constantly repeated with a periodicity of approximately 1 s. Whirls of a given direction became disorganized and then re-formed, usually into whirls moving in the opposite direction. Pattern elements were also organized with respect to one another in the colony. Neighboring whirls usually turned in opposite directions. This correlation decreased as a function of distance between whirls. Fluid flows associated with whirls and jets were measured by observing the movement of marker latex spheres added to colonies. The average velocity of markers traveling in whirls was 19 microm/s, whereas those traveling in jets moved at 27 microm/s. The paths followed by markers were aligned with the direction of cell motion, suggesting that cells create flows moving with them into whirls and along jets. When colonies became dry, swimming motions ceased except in regions close to the periphery and in isolated islands where cells traveled in slow whirls at about 4 microm/s. The addition of water resulted in immediate though transient rapid swimming (> 80 microm/s) in characteristic whirl and jet patterns. The rate of swimming decreased to 13 microm/s within 2 min, however, as the water diffused into the agar. Organized swimming patterns were nevertheless preserved throughout this period. These findings show that cell swimming in colonies is highly organized.

Bacillus subtilis↗
PubMed1994

THE SWIMMING OF UNIPOLAR CELLS OF SPIRILLUM VOLUTANS: THEORY AND OBSERVATIONS

Bright-field high-speed cinemicrography was employed to record the swimming of six unipolar cells of Spirillum volutans. A complete set of geometrical parameters for each of these six cells, which are of typical but varying dimensions, was measured experimentally. For each cell, the mean swimming linear and angular speeds were measured for a period representing an exact number of flagellar cycles (at least four and up to 12 cycles). Two independent sets of measurements were carried out for each cell, one relating to the trailing and the other to the leading configuration of the flagellar bundle. The geometry of these cells was numerically modelled with curved isoparametric boundary elements (from the measured geometrical parameters), and an existing boundary element method (BEM) program was applied to predict the mean swimming linear and angular speeds. A direct comparison between the experimentally observed swimming speeds and those of the BEM predictions is made. For a typical cell, a direct comparison of the swimming trajectory, in each of the trailing and the leading flagellar configurations, was also included. Previous resistive force theory (RFT) as well as slender body theory (SBT) models are both restricted to somewhat non-realistic 'slender body' geometries, and they both fail to consider swimming kinematics. The present BEM model, however, is applicable to organisms with arbitrary geometry and correctly accounts for swimming kinematics; hence, it agrees better with experimental observations than do the previous models.

Journal Article↗
PubMed1994

SWIMMING METABOLISM OF WILD-TYPE AND CLONED ZEBRAFISH BRACHYDANIO RERIO

The availability of a gynogenetic isogenic homozygous diploid clonal strain (C) of the zebrafish (Brachydanio rerio), combined with the small adult body size of the species, made possible a study of the following two questions. (1) Is the genetic uniformity of a group of fish reflected in decreased variability of features of organismic performance physiology? (2) Is the metabolic cost of subcarangiform swimming significantly different in small fishes compared with large ones? Wild-type (WT) and C strain zebrafish maintained at 28 °C can all swim very rapidly [up to relative swimming speeds of 13 body lengths s-1 (BL s-1)] for extended periods (at least 2 h) without visibly tiring. Oxygen consumption rates were measured for both types at swimming speeds of 1.5­13 BL s-1. Whole-body lactate concentrations were also measured during routine activity and after prolonged exercise for both fish types. The slopes of the linear regressions between the logarithm of mass-specific oxygen consumption rates and relative swimming speeds for WT zebrafish were low (0.010­0.024) and were not significantly different from zero. Regression slopes were also low (0.009­0.026), but different from zero, for C zebrafish. Standard metabolic rates were 0.60­1.54 and 0.40­0.85 ml O2 g-1 h-1 for WT and C zebrafish respectively. Variances of slopes were significantly larger for WT than for C fish. Whole-body lactate concentrations and their variances were not significantly different between types and between rested and exercised fishes. The results demonstrate unusual swimming performance capacities, a remarkably low cost of swimming and some reductions in variability of C fish. Several possible explanations for the results are discussed.

Journal Article↗
PubMed1997

Motor patterns of labriform locomotion: kinematic and electromyographic analysis of pectoral fin swimming in the labrid fish Gomphosus varius

Labriform locomotion is a widespread swimming mechanism in fishes during which propulsive forces are generated by oscillating the pectoral fins. We examined the activity of the six major muscles that power the pectoral fin of the bird wrasse Gomphosus varius (Labridae: Perciformes). The muscles studied included the fin abductors (arrector ventralis, abductor superficialis and abductor profundus) and the fin adductors (arrector dorsalis, adductor superficialis and adductor profundus). Our goals were to determine the pattern of muscle activity that drives the fins in abduction and adduction cycles during pectoral fin locomotion, to examine changes in the timing and amplitude of electromyographic (EMG) patterns with increases in swimming speed and to correlate EMG patterns with the kinematics of pectoral fin propulsion. EMG data were recorded from three individuals over a range of swimming speeds from 15 to 70 cm s-1 (1­4.8 TL s-1, where TL is total body length). The basic motor pattern of pectoral propulsion is alternating activity of the antagonist abductor and adductor groups. The downstroke is characterized by activity of the arrector ventralis muscle before the other abductors, whereas the upstroke involves nearly synchronous activity of the three adductors. Most EMG variables (duration, onset time, amplitude and integrated area) showed significant correlations with swimming speeds. However, the timing and duration of muscle activity are relatively constant across speeds when expressed as a fraction of the stride period, which decreases with increased velocity. Synchronous recordings of kinematic data (maximal abduction and adduction) with EMG data revealed that activity in the abductors began after maximal adduction and that activity in the adductors began nearly synchronously with maximal abduction. Thus, the pectoral fin mechanism of G. varius is activated by positive work from both abductor and adductor muscle groups over most of the range of swimming speeds. The adductors produce some negative work only at the highest swimming velocities. We combine information from pectoral fin morphology, swimming kinematics and motor patterns to interpret the musculoskeletal mechanism of pectoral propulsion in labrid fishes.

Journal Article↗
PubMed1998

The impact of endurance training on arterial plasma K+ levels and swimming performance of rainbow trout

Arterial plasma K+ and lactate concentrations ([K+]a and [lactate]a), as well as blood oxygenation status, were measured in relation to increasing swimming speeds in rainbow trout Oncorhynchus mykiss. Neither [K+]a nor [lactate]a changed at swimming speeds below 1.5 BL s-1, where BL is total body length. Between 1.5 and 2.0 BL s-1, [K+]a started to increase, and above 2.0 BL s-1 both [K+]a and [lactate]a increased with swimming speed. Training shifted the onset of these increases to higher swimming speeds and increased the critical swimming speed (Ucrit) from 2.4 to 3.0 BL s-1. Blood oxygen content showed no changes in control fish, whereas in trained fish it increased by 22 % at the final swimming speed. From the [K+]a data, we suggest that no loss of K+ occurred from the working muscle at low swimming speeds, allowing an unlimited endurance, whereas moderate and higher speeds were probably associated with a loss of K+ from the working muscles, indicating a limited endurance.

Journal Article↗
PubMed1976

Rhythmic swimming activity in neurones of the isolated nerve cord of the leech.

1. Repeating bursts of motor neurone impulses have been recorded from the nerves of completely isolated nerve cords of the medicinal leech. The salient features of this burst rhythm are similar to those obtained in the semi-intact preparation during swimming. Hence the basic swimming rhythm is generated by a central oscillator. 2. Quantitative comparisons between the impulse patterns obtained from the isolated nerve cord and those obtained from a semi-intact preparation show that the variation in both dorsal to ventral motor neurone phasing and burst duration with swim cycle period differ in these two preparations. 3. The increase of intersegmental delay with period, which is a prominent feature of swimming behaviour of the intact animal, is not seen in either the semi-intact or isolated cord preparations. 4. In the semi-intact preparation, stretching the body wall or depolarizing an inhibitory motor neurone changes the burst duration of excitatory motor neurones in the same segment. In the isolated nerve cord, these manipulations also change the period of the swim cycle in the entire cord. 5. These comparisons suggest that sensory input stabilizes the centrally generated swimming rhythm, determines the phasing of the bursts of impulses from dorsal and ventral motor neurones, and matches the intersegmental delay to the cycle period so as to maintain a constant body shape at all rates of swimming.

Action Potentials↗
PubMedDate not supplied

Male:female sex ratio in births resulting from IVF according to swim-up versus Percoll preparation of inseminated sperm.

Two centers have independently reported a higher rate of male to female births following insemination of sperm prepared by a modified swim-up technique. The principle of the modified swim-up is that a small percentage of the x-bearing sperm are the fastest and travel to the top of the supernatant, followed by the y-bearing sperm; the bulk of the x-bearing sperm remain in the pellet. In this technique, the very top layer is discarded and the resulting supernatant is collected, leaving only the pellet. In contrast, with the conventional swim-up technique, the entire supernatant is collected. The study presented herein retrospectively evaluated the male to female sex ratio of births from in vitro fertilization using standard swim-up technique and compared these results to the ratio obtained from separating with Percoll. There were 53% male births with swim-up vs. 54% with Percoll in singleton pregnancies and 51% males with swim-up vs. 40% with Percoll with multiple births. Thus, conventional swim-up alone does not increase percentage of male births.

Cell Separation↗
PubMed1989

Structural and functional properties of reticulospinal neurons in the early-swimming stage Xenopus embryo.

This study presents direct evidence that in Xenopus laevis embryos ipsi- and contralaterally descending reticulospinal fibers from the caudal brain stem project to the spinal cord, where they directly contact primary motoneurons. At stage 30, occasional contacts between primary motoneurons and descending axons are present. These contacts are possibly already functional since presynaptic vesicles were sometimes observed. Furthermore, the physiological data obtained in this study suggest that reticulospinal neurons in the caudal brain stem are involved in the central generation of early swimming. The first ingrowth of reticulospinal axons was observed in the rostral spinal cord after application of HRP to the caudal brain stem of stage 27/28 embryos. By stage 32, many supraspinal axons could be found in the spinal cord at the level of the 12/13th myotome, near the time of the first rhythmic swimming. Both lamellipodial and varicose growth cones were found. Intracellular recordings from the brain stem and extracellular recordings from the myotomal muscles in curarized embryos around stage 30 revealed neurons in the caudal brain stem which were active during early fictive swimming. After intracellular staining with Lucifer yellow neurons with descending axons were found in the brain-stem reticular formation. These reticulospinal neurons showed "motoneuron-like" phasic activity, producing one spike each swimming cycle. Rhythmically occurring spikes with swimming periodicity were superimposed on a sustained depolarization level of some 5-30 mV. Reticulospinal neurons in the brain stem resemble descending interneurons in the spinal cord by their morphology, projection pattern, and activity during early swimming. Reticulospinal neurons and descending interneurons might therefore form one continuous population of projecting interneurons with a different location but a similar function. In support of this we propose that the embryonic brain-stem reticular formation forms part of the swimming pattern generator.

Animals↗
PubMed1997

[Analysis of the swimming pattern and the velocity of bacteria using video tracking method].

The swimming patterns and the velocities of several flagellated bacteria were measured by a computer assisted video tracking method. The moving path of the individual bacterium revealed that the bacterium frequently changed its swimming direction and velocity. The velocity among bacterial strains varies widely. In low viscous environment. Campylobacter jejuni has characteristic swimming pattern with frequent changes in their swimming direction. As the viscosity increase, C. jejuni increases its velocity at a little higher viscosity of 3 centipoise (cP) and secondly increases at about 40 cP. Different from other flagellated bacteria, the swimming pattern of C. jejuni in these two velocity peaks were changed. C. jejuni exhibited continuously forward moving path in the first peak, but in the second it repeated back and forth swimming pattern. We thus assumed that C. jejuni may use a different swimming mode in high viscous media from the original mode mediated by the propelling force of the flagella. This method is useful for a detail analysis of bacterial movement and moving patterns in different environmental conditions.

Bacterial Physiological Phenomena↗
PubMed1999

Morphometrical comparison of human spermatozoa obtained from semen and swim-up methodology.

Because morphology is regularly established in semen smears, but not in swim-up spermatozoa, we were interested in comparing some morphological parameters of semen and swim-up spermatozoa to establish if the cells selected by the swim-up method were morphologically similar to those considered normal in semen. Normal human semen samples were divided into two aliquots. One of these aliquots was washed by centrifugation with B2 medium and sperm smears were prepared with the resulting pellet as a control. The other aliquot was used to perform swim-up separation and the spermatozoa from the supernatant were used as experimental smears. Both groups were stained according to the triple stain technique and spontaneous acrosome reaction and viability were determined. Video microscopy and computer-assisted image processing of live and non-reacted sperm cells were used to establish morphometrical parameters of the sperm head in both populations. The following set of morphometrical parameters were considered: width, length, width/length ratio, acrosome area, head area, and acrosome area/head area ratio. An increase in head width, a decrease in head length and a subsequent increase of width/length ratio were found in swim-up cells compared with the control group. A slight increase in acrosome area/head area ratio was also observed in swim-up supermatozoa. Through the swim-up methodology we were able to select a subpopulation of oval shaped heads with spermatozoa having a bigger acrosome area in comparison to semen.

Acrosome↗
PubMed1986

Erosion of dental enamel among competitive swimmers at a gas-chlorinated swimming pool.

In September 1982, two Charlottesville, Virginia, residents were found by their dentists to have general erosion of dental enamel consistent with exposure to acid. Both patients were competitive swimmers at the same private club pool. No other common exposure could be determined. An epidemiologic survey was made of 747 club members. Symptoms compatible with dental enamel erosion were reported by 3% of nonswimmers (9/295), 12% of swimmers who were not members of the swim team (46/393), and 39% of swim team members (23/59). All four swimmers with clinically verified dental enamel erosion had trained regularly in the pool for competitive swimming meets, compared with one of eight matched swimmers without enamel erosion. Examination of the implicated swimming pool revealed a gas-chlorinated pool with corrosion of metal fixtures and etching of cement exposed to the pool water. A pool water sample had a pH of 2.7, i.e., an acid concentration approximately 100,000 times that recommended for swimming pools (pH 7.2-8.0). A review of pool management practices revealed inadequate monitoring of pool water pH. Acid erosion of dental enamel--"swimmer's erosion"--is a painful, costly, irreversible condition which can be caused by inadequately maintained gas-chlorinated swimming pools.

Adolescent↗
PubMed1979

Swimming ability of children: a survey of 4000 Queensland children in a high drowning region.

The swimming ability of 4128 Queensland school children was studied. The median age for swimming 10 metres is 6.5 years. Ninety-five percent of children are able to swim by 11 years of age. Cumulative frequency curves, by age, are presented for the ability to swim 10 and 50 metres: the latter distance is of relevance in boating accidents. Twenty percent fewer children from lower socioeconomic levels are able to swim. Water safety training is as important as swimming lessons.

Adolescent↗
PubMed1991

An automated assay for quantifying the swimming behavior of Paramecium and its use to study cation responses.

Paramecium tetraurelia is a ciliated protist that alters its swimming behavior in response to various stimuli. Like the sensory responses of many organisms, these responses in Paramecium show adaptation to continued stimulation. For quantitative studies of the initial response to stimulation, and of the time course of adaptation, we have developed a computerized motion analysis assay that can detect deviations from the normal swimming pattern in a population of cells. The motion of an average of ten cells was quantified during periods ranging from 15 to 60 seconds, with a time resolution of 1/15 seconds. During normal forward swimming, the maximum deviation from a straight-line path was less than 17 degrees. Path deviations above this threshold value were defined as changes in swimming direction. The percentage of total path time that cells spent deviating from forward swimming was defined as percent directional changes (PDC). This parameter was used to construct dose-response curves for the behavioral effects of various externally added cations known to induce behavioral changes and also to show the time course of adaptation to a depolarizing K+ stimulus. This assay is a valuable tool for studies of chemoeffectors or mutations that alter the swimming behavior of Paramecium and may also be applicable to other motile organisms.

Animals↗
PubMed2005

Modelling energetic costs of fish swimming.

The oxygen consumption rates of two cyprinid fishes, carp (Cyprinus carpio L.) and roach (Rutilus rutilus (L.)), were analysed for a wide range of body mass and swimming speed by computerized intermittent-flow respirometry. Bioenergetic models were derived, based on fish mass (M) and swimming speed (U), to predict the minimal speed and mass-specific active metabolic rate (AMR) in these fishes (AMR=aMbUc). Mass and speed together explained more than 90% of the variance in total swimming costs in both cases. The derived models show that carp consume far more oxygen at a specific speed and body mass, thus being less efficient in energy use during swimming than roach. It was further found that in carp (AMR=0.02M0.8U0.95) the metabolic increment during swimming is more strongly effected by speed, whereas in roach (AMR=0.02M0.93U0.6) it is more strongly effected by body mass. The different swimming traits of carp and roach are suitable for their respective lifestyles and ecological demands.

Animals↗
PubMed1985

Control of swimming in the hydrozoan jellyfish Aequorea aequorea: direct activation of the subumbrella.

The epithelial cells that overlie the inner nerve ring of the hydrozoan jellyfish Aequorea aequorea were investigated ultrastructurally and electrophysiologically. The structurally unspecialized epithelial cells are interconnected by gap junctions and are electrically active during swimming as a single, long-duration action potential was recorded during each swim contraction. Intercellular electrical- and dye-coupling was demonstrated within the epithelial region extending into the velum and subumbrellar regions. Excitatory post-synaptic potentials were recorded from epithelial cells following swim motorneuron spikes with a short latency. Psps were up to 60 mV in amplitude and, when triggered in bursts, showed summation provided the interpulse interval was less than 25-35 ms. The initial gap in each of a series of bursts showed facilitation with the first few swim contractions following a period of inactivity. In actively swimming medusae, psp amplitude was relatively constant. The reversal potential for epithelial psp was estimated at between 0 and +20 mV. Spontaneous psps spread throughout the epithelial region electronically, but the amplitude decrease with conducting distance was less than that for current pulses injected into individual epithelial cells. This presumably represents the effect of widespread synaptic activation of epithelial cells via multiple input sites throughout the inner nerve ring as opposed to point-source input in current injection experiments. During a radial response, action potential amplitude was decreased and rise time increased due to decremental conduction through the inhibited region. It is postulated that conduction of a full action potential requires that electrotonic current spread from adjacent, active epithelial cells occur in synchrony with synaptic input from swim motoneurons.

Action Potentials↗
PubMed2004

Xenobiotic substances such as PCB mixtures (Aroclor 1254) and TBT can influence swimming behavior and biotransformation activity (GST) of carp (Cyprinus carpio).

Different groups of carp were treated with polychlorinated biphenyl (PCB) or tributyltin (TBT), and possible effects of the chemicals on the swimming behavior of the carp were examined using the BehavioQuant system. By evaluating quantitative behavioral parameters of the animals, it became evident that exposure to high concentrations of chemicals (organotin, 7 microg L(-1), or polychlorinated biphenyl, 22 microg L(-1)) severely affected the carp, causing a significant change in their swimming speed. TBT stress led to a rapid decrease in mean swimming activity. A decrease in the preferred swimming depth was observed in TBT- and PCB-exposed fish. Animals exposed to PCB reduced their mean daily activity and increased their mean swimming speed in the nighttime during the second week of exposure. Therefore, our findings imply that the fish were adapted to cope with the chemicals after the second week of exposure. Furthermore, our results showed that low concentrations (TBT, 0.3 and 2 microg L(-1), or PCB, 14 microg L(-1)) did not significantly alter any quantified parameters of swimming behavior. In addition, the direct effects of chemicals on enzyme activity (GST) were determined. Measurement of soluble glutathione-S-transferase activity of fish liver or gills showed a significant elevation after exposure to PCB (0.1 or 22 microg L(-1)) or TBT (0.8 or 7 microg L(-1)). We had to conclude that the two different end points tested generally are useful as biomarkers of exposure and for investigations of energy resources in organisms under the influence of toxic stress.

Animals↗