Changes In Swimming Speed Research Articles

Physiological and transcriptomic changes of zebrafish (Danio rerio) in response to Isopropylate Triphenyl Phosphate (IPPP) exposure

Isopropylate Triphenyl Phosphate (IPPP), a novel organophosphorus flame retardant, has become a widespread environmental pollutant. However, the toxic effects and mechanisms of IPPP remain unclear. In this study, we evaluated the neurodevelopmental toxicity effects of IPPP on zebrafish embryonic development, neurobehavior, and physiological and transcriptomic changes. The results showed that IPPP induced adverse developments such as low survival rates and hatching rates, decreased body length and eye distance, and also led to increased heart rates and embryonic malformation rates. The developmental defects mainly included typical pericardial edema, eye deformities, and a reduction in the number of newborn neurons. Mitochondrial energy metabolism disorders and apoptosis of cardiomyocytes may be responsible for heart malformation. Behavioral results showed that IPPP caused abnormal changes in swimming speed, total swimming distance and trajectory, and showed a low-dose effect. In addition, the decreased activity of neurotransmitters such as acetylcholinesterase (AchE) and dopamine (DA), and the changes in genes related to the central nervous system (CNS) and metabolism pathway may be the causes of neurodevelopmental toxicity of IPPP. Meanwhile, IPPP induced oxidative stress and apoptosis, and changed the ATPase activity of zebrafish larvae by altering nuclear factor erythroid2-related factor 2 (Nrf2) and mitochondrial signaling pathways, respectively. Transcriptome sequencing results indicated that Cytochrome P450 and drug metabolism, Energy metabolism-related pathways, Glutathione metabolism, Retinoid acid (RA) and REDOX signaling pathways were significantly enriched, and most of the genes in these pathways were up-regulated after IPPP treatment, which may be new targets for IPPP-induced neurodevelopment. In summary, the results of this study provide an important reference for a comprehensive assessment of the toxic effects and health risks of the new pollutant IPPP.

Viral Chemotaxis of Paramecium Bursaria Altered by Algal Endosymbionts.

Chemotaxis is widespread across many taxa and often aids resource acquisition or predator avoidance. Species interactions can modify the degree of movement facilitated by chemotaxis. In this study, we investigated the influence of symbionts on Paramecium bursaria's chemotactic behavior toward chloroviruses. To achieve this, we performed choice experiments using chlorovirus and control candidate attractors (virus stabilization buffer and pond water). We quantified the movement of Paramecia grown with or without algal and viral symbionts toward each attractor. All Paramecia showed some chemotaxis toward viruses, but cells without algae and viruses showed the most movement toward viruses. Thus, the endosymbiotic algae (zoochlorellae) appeared to alter the movement of Paramecia toward chloroviruses, but it was not clear that ectosymbiotic viruses (chlorovirus) also had this effect. The change in behavior was consistent with a change in swimming speed, but a change in attraction remains possible. The potential costs and benefits of chemotactic movement toward chloroviruses for either the Paramecia hosts or its symbionts remain unclear.

Phenotypic response to different predator strategies can be mediated by temperature.

Temperature change affects biological systems in multifaceted ways, including the alteration of species interaction strengths, with implications for the stability of populations and communities. Temperature-dependent changes to antipredatory responses are an emerging mechanism of destabilization and thus there is a need to understand how prey species respond to predation pressures in the face of changing temperatures. Here, using ciliate protozoans, we assess whether temperature can alter the strength of phenotypic antipredator responses in a prey species and whether this relationship depends on the predator's hunting behavior. We exposed populations of the ciliate Paramecium caudatum to either (i) a sit-and-wait generalist predator (Homalozoon vermiculare) or (ii) a specialized active swimmer predator (Didinium nasutum) across two different temperature regimes (15 and 25°C) to quantify the temperature dependence of antipredator responses over a 24-h period. We utilized a novel high-throughput automated robotic monitoring system to track changes in the behavior (swimming speed) and morphology (cell size) of P. caudatum at frequencies and resolutions previously unachievable by manual sampling. The change in swimming speed through the 24 h differed between the two temperatures but was not altered by the presence of the predators. In contrast, P. caudatum showed a substantial temperature-dependent morphological response to the presence of D. nasutum (but not H. vermiculare), changing cell shape toward a more elongated morph at 15°C (but not at 25°C). Our findings suggest that temperature can have strong effects on prey morphological responses to predator presence, but that this response is potentially dependent on the predator's feeding strategy. This suggests that greater consideration of synergistic antipredator behavioral and physiological responses is required in species and communities subject to environmental changes.

Potential of nobiletin against Alzheimer's disease through inhibiting neuroinflammation.

This study aimed to explore the mechanism of Nobiletin attenuating Alzheimer's disease (AD) by inhibiting neuroinflammation. The expression of inflammatory cytokines and HMGB-1 in serum of AD patients were examined. Microglia (MGs) were treated with different doses of Nobiletin before LPS and Nigericin induction. Cell viability and apoptosis were determined by CCK-8 and TUNEL assays, respectively. APP/PS1 mice were gavaged with Nobiletin, and Morris water maze (MWM) was established to record swimming speed, escape latency, the number of platform crossings, and time spent in the platform quadrant. MGs activation in brain tissues was evaluated by immunofluorescence. The expression of pyroptosis-related proteins, inflammatory cytokines, and HMGB-1 was determined in the hippocampus and MGs. The levels of inflammatory cytokines and HMGB-1 were high in serum of AD patients. Treatment with different concentrations of Nobiletin prominently enhanced cell viability and reduced apoptosis and the expression of inflammatory cytokine and pyroptosis-related proteins in LPS + Nigericin-induced MGs. Gavage of different doses of Nobiletin into APP/PS1 mice shortened the escape latency in mice, diminished MGs activation in brain tissues, and remarkably elevated the number of platform crossings and the time spent in the platform quadrant without obvious change in swimming speed, suggesting that Nobiletin improved the spatial learning and memory abilities in APP/PS1 mice. The expression of pyroptosis-related proteins, HMGB-1, and inflammatory cytokines was decreased dramatically by Nobiletin in the hippocampus of APP/PS1 mice. Nobiletin can inhibit neuroinflammation by inhibiting HMGB-1, pyroptosis-related proteins, and inflammatory cytokines, thus mitigating AD.

Gain of Spontaneous clpX Mutations Boosting Motility via Adaption to Environments in Escherichia coli.

Motility is finely regulated and is crucial to bacterial processes including colonization and biofilm formation. There is a trade-off between motility and growth in bacteria with molecular mechanisms not fully understood. Hypermotile Escherichia coli could be isolated by evolving non-motile cells on soft agar plates. Most of the isolates carried mutations located upstream of the flhDC promoter region, which upregulate the transcriptional expression of the master regulator of the flagellum biosynthesis, FlhDC. Here, we identified that spontaneous mutations in clpX boosted the motility of E. coli largely, inducing several folds of changes in swimming speed. Among the mutations identified, we further elucidated the molecular mechanism underlying the ClpXV78F mutation on the regulation of E. coli motility. We found that the V78F mutation affected ATP binding to ClpX, resulting in the inability of the mutated ClpXP protease to degrade FlhD as indicated by both structure modeling and in vitro protein degradation assays. Moreover, our proteomic data indicated that the ClpXV78F mutation elevated the stability of known ClpXP targets to various degrees with FlhD as one of the most affected. In addition, the specific tag at the C-terminus of FlhD being recognized for ClpXP degradation was identified. Finally, our transcriptome data characterized that the enhanced expression of the motility genes in the ClpXV78F mutations was intrinsically accompanied by the reduced expression of stress resistance genes relating to the reduced fitness of the hypermotile strains. A similar pattern was observed for previously isolated hypermotile E. coli strains showing high expression of flhDC at the transcriptional level. Hence, clpX appears to be a hot locus comparable to the upstream of the flhDC promoter region evolved to boost bacterial motility, and our finding provides insight into the reduced fitness of the hypermotile bacteria.

Phototactic responses in four monogenean oncomiracidia.

Phototaxis is the common behavioral response exhibited by the oncomiracidia of various monogeneans. However, the changes in the oncomiracidial swimming behavior in response to light cues are not well understood. Here, we investigated the light responses of four monogeneans that are important pathogens in mariculture, namely Benedenia epinepheli, Benedenia seriolae, Neobenedenia girellae, and Heteraxine heterocerca. The swimming trajectory and speed of oncomiracidia of each species were assessed in a glass Petri dish with an LED light placed adjacent to it, based on three different light responses: LED light in the off position (normal swimming), LED light in the on position (phototactic behavior), and immediately (< 5s) after switching the LED light off (photophobic behavior). The oncomiracidia of all four species exhibited positive phototactic and photophobic responses; however, the change in swimming speed between each response differed among the species. The oncomiracidia of three species (B. epinepheli, N. girellae, and H. heterocerca) exhibited high swimming speed, as a phototactic response; in contrast, the oncomiracidia of B. seriolae exhibited reduced swimming speed when moving toward the light source. Benedenia epinepheli and H. heterocerca exhibited the highest swimming speed during the phototaxis phase, whereas B. seriolae and N. girellae exhibited the highest swimming speed during the photophobic phase. These light responses are considered adaptive traits to increase the chance of encountering and infecting suitable hosts in nature, and such responses could potentially be applied to the control of parasite infections in aquaculture.

Does sports-specific training improve measures of impairment developed for para sport classification? A multiple-baseline, single-case experiment

ABSTRACT Conceptually, sports-specific training should not influence measures of impairment used to classify Para athletes. This study evaluated the extent to which measures of strength, range of movement and coordination developed for Para swimming classification changed in response to a performance-focused swimming programme. A five-phase multiple-baseline, single-case experimental research design was utilized. Three participants with cerebral palsy and high support needs completed the 64-week study, which included two 16-week performance-focused swimming training blocks. Swimming speed, isometric shoulder extension strength, shoulder flexion range of movement and upper limb coordination were monitored throughout. Interrupted Time-Series Simulation Method analysis demonstrated large, significant changes in swimming speed (m/s) during the first (d = 2.17; 95% CI 0.45–3.88; p = 0.01) and second (d = 2.59; 95% CI 1.66–3.52; p = 0.00) training blocks. In contrast, changes in strength, range of movement and coordination were predominantly trivial and non-significant. This was the first study to investigate training responsiveness of measures developed for Para sport classification. Results indicate that despite significantly improved swimming performance, impairment measures remained relatively stable, and therefore these measures of impairment may be valid for the purposes of Para swimming classification. Further research is required in elite athletes, different sports and different impairment types.

In situ structure of the Caulobacter crescentus flagellar motor and visualization of binding of a CheY-homolog.

Bacterial flagellar motility is controlled by the binding of CheY proteins to the cytoplasmic switch complex of the flagellar motor, resulting in changes in swimming speed or direction. Despite its importance for motor function, structural information about the interaction between effector proteins and the motor are scarce. To address this gap in knowledge, we used electron cryotomography and subtomogram averaging to visualize such interactions inside Caulobacter crescentus cells. In C. crescentus, several CheY homologs regulate motor function for different aspects of the bacterial lifestyle. We used subtomogram averaging to image binding of the CheY family protein CleD to the cytoplasmic Cring switch complex, the control center of the flagellar motor. This unambiguously confirmed the orientation of the motor switch protein FliM and the binding of a member of the CheY protein family to the outside rim of the C ring. We also uncovered previously unknown structural elaborations of the alphaproteobacterial flagellar motor, including two novel periplasmic ring structures, and the stator ring harboring eleven stator units, adding to our growing catalog of bacterial flagellar diversity.

A three-dimensional model of flagellar swimming in a Brinkman fluid

We investigate three-dimensional flagellar swimming in a fluid with a sparse network of stationary obstacles or fibres. The Brinkman equation is used to model the average fluid flow where a flow-dependent term, including a resistance parameter that is inversely proportional to the permeability, captures the effects of the fibres on the fluid. To solve for the local linear and angular velocities that are coupled to the flagellar motion, we extend the method of regularized Brinkmanlets to incorporate a Kirchhoff rod, discretized as point forces and torques along a centreline. Representing a flagellum as a Kirchhoff rod, we investigate emergent waveforms for different preferred strain and twist functions. Since the Kirchhoff rod formulation allows for out-of-plane motion, in addition to studying a preferred planar sine wave configuration, we also study a preferred helical configuration. Our numerical method is validated by comparing results to asymptotic swimming speeds derived for an infinite-length cylinder propagating planar or helical waves. Similar to the asymptotic analysis for both planar and helical bending, we observe that with small amplitude bending, swimming speed is always enhanced relative to the case with no fibres in the fluid (Stokes) as the resistance parameter is increased. For regimes not accounted for with asymptotic analysis, i.e. large amplitude planar and helical bending, our model results show a non-monotonic change in swimming speed with respect to the resistance parameter; a maximum swimming speed is observed when the resistance parameter is near one. The non-monotonic behaviour is due to the emergent waveforms; as the resistance parameter increases, the swimmer becomes incapable of achieving the amplitude of its preferred configuration. We also show how simulation results of slower swimming speeds for larger resistance parameters are actually consistent with the asymptotic swimming speeds if work in the system is fixed.

Swimming Energy Economy in Bottlenose Dolphins Under Variable Drag Loading

Instrumenting animals with tags contributes additional resistive forces (weight, buoyancy, lift and drag) that may result in increased energetic costs; however, additional metabolic expense can be moderated by adjusting behaviour to maintain power output. We sought to increase hydrodynamic drag for near-surface swimming bottlenose dolphins, to investigate the metabolic effect of instrumentation. In this experiment, we investigate whether (1) metabolic rate increases systematically with hydrodynamic drag loading from tags of different sizes or (2) whether tagged individuals modulate speed, swimming distance and/or fluking motions under increased drag loading. We detected no significant difference in oxygen consumption rates when four male dolphins performed a repeated swimming task, but measured swimming speeds that were 34% (>1 m s-1) slower in the highest drag condition. To further investigate this observed response, we incrementally decreased and then increased drag in six loading conditions. When drag was reduced, dolphins increased swimming speed (+1.4 m s-1; +45%) and fluking frequency (+0.28 Hz; +16%). As drag was increased, swimming speed (-0.96 m s-1; -23%) and fluking frequency (-14 Hz; 7%) decreased again. Results from computational fluid dynamics simulations indicate that the experimentally observed changes in swimming speed would have maintained the level of external drag forces experienced by the animal. Together, these results indicate that dolphins may adjust swimming speed to modulate the drag force opposing their motion during swimming, adapting their behaviour to maintain a level of energy economy during locomotion.

Ontogenetic changes in swimming speed of silver carp, bighead carp, and grass carp larvae: implications for larval dispersal.

Bighead, silver, and grass carps are invasive in the waterways of central North America, and grass carp reproduction in tributaries of the Great Lakes has now been documented. Questions about recruitment potential motivate a need for accurate models of egg and larval dispersal. Quantitative data on swimming behaviors and capabilities during early ontogeny are needed to improve these dispersal models. We measured ontogenetic changes in routine and maximum swimming speeds of bighead, grass, and silver carp larvae. Daily measurements of routine swimming speed were taken for two weeks post-hatch using a still camera and the LARVEL program, a custom image-analysis software. Larval swimming speed was calculated using larval locations in subsequent image frames and time between images. Using an endurance chamber, we determined the maximum swimming speed of larvae (post-gas bladder inflation) for four to eight weeks post-hatch. For all species, larval swimming speeds showed similar trends with respect to ontogeny: increases in maximum speed, and decreases in routine speed. Maximum speeds of bighead and grass carp larvae were similar and generally faster than silver carp larvae. Routine swimming speeds of all larvae were highest before gas bladder inflation, most likely because gas bladder inflation allowed the fish to maintain position without swimming. Downward vertical velocities of pre-gas bladder inflation fish were faster than upward velocities. Among the three species, grass carp larvae had the highest swimming speeds in the pre-gas bladder inflation period, and the lowest speeds in the post-gas bladder inflation period. Knowledge of swimming capability of these species, along with hydraulic characteristics of a river, enables further refinement of models of embryonic and larval drift.

Bioenergetic consequences of warming rivers to adult Atlantic salmon Salmo salar during their spawning migration

Abstract Climate change poses a challenge to wild fishes, yet little is known about the behavioural use and metabolic consequences of thermally heterogeneous water encountered by wild salmon during their energetically demanding upstream spawning migration. Temperature, body size and activity levels were modelled to predict energy depletion of salmon during their spawning migration in rivers. Archival temperature loggers revealed the thermal habitat of adult migrating Atlantic salmon (Salmo salar Salmonidae), which we used to apply bioenergetics models that estimated size‐dependent temperature‐driven metabolic expenditures as part of the costs of the migration. Between July 16 and August 19, the mean water temperature experienced by salmon (tFISH) ranged from 11.5 to 18.0°C (14.5 ± 1.2 SD °C) and closely followed the ambient surface water temperature (tRIVER) of the river (11.5–18.5°C; 14.8 ± 1.4°C) such that the regression equation tFISH = 3.24 + 0.76 (tRIVER) was highly correlated with observations (R2 = 0.94). Although temperature increases were predicted and confirmed to increase energetic costs, rates of energy depletion were more sensitive to changes in swimming speed and body size than to temperature increases in the range explored for this system. We conclude that warming could contribute to changing life history phenotypes of salmon in some rivers, for example, delayed river entry or reduced probability of iteroparity, with potentially more dire consequences for smaller individuals.

Acoustic dose-behavioral response relationship in sea bass (Dicentrarchus labrax) exposed to playbacks of pile driving sounds

The foundations of offshore wind turbines are attached to the sea bed by percussion pile driving. Pile driving sounds may affect the behavior of fish. Acoustic dose-behavioral response relationships were determined for sea bass in a pool exposed for 20 min to pile driving sounds at seven mean received root-mean-square sound pressure levels [SPLrms; range: 130–166 dB re 1 μPa; single strike sound exposure level (SELss) range: 122–158; 6 dB steps]. Initial responses (sudden, short-lived changes in swimming speed and direction) and sustained responses (changes in school cohesion, swimming depth, and speed) were quantified. The 50% initial response threshold occurred at an SELss of 131 dB re 1 μPa2 s for 31 cm fish and 141 dB re 1 μPa2 s for 44 cm fish; the small fish thus reacted to lower SELss than the large fish. Analysis showed that there is no evidence, even at the highest sound level, for any consistent sustained response to sound exposure by the study animals. If wild sea bass are exposed to pile driving sounds at the levels used in the present study, there are unlikely to be any adverse effects on their ecology, because the initial responses after the onset of the piling sound observed in this study were short-lived.

The effect of gait on swimming in viscoelastic fluids

In this paper, we give formulas for the swimming of simplified two-dimensional bodies in complex fluids using the reciprocal theorem. By way of these formulas we calculate the swimming velocity due to small-amplitude deformations on the simplest of these bodies, a two-dimensional sheet, to explore general conditions on the swimming gait under which the sheet may move faster, or slower, in a viscoelastic fluid compared to a Newtonian fluid. We show that in general, for small amplitude deformations, a speed increase can only be realized by multiple deformation modes in contrast to slip flows. Additionally, we show that a change in swimming speed is directly due to a change in thrust generated by the swimmer.

Swimming fluctuations of micro-organisms due to heterogeneous microstructure.

Swimming microorganisms in biological complex fluids may be greatly influenced by heterogeneous media and microstructure with length scales comparable to the organisms. A fundamental effect of swimming in a heterogeneous rather than homogeneous medium is that variations in local environments lead to swimming velocity fluctuations. Here we examine long-range hydrodynamic contributions to these fluctuations using a Najafi-Golestanian swimmer near spherical and filamentous obstacles. We find that forces on microstructures determine changes in swimming speed. For macroscopically isotropic networks, we also show how the variance of the fluctuations in swimming speeds are related to density and orientational correlations in the medium.

Variation in swimming speed of Escherichia coli in response to attractant.

It is well known that Escherichia coli executes chemotactic motion in response to chemical cues by modulating the flagellar motor bias alone. However, previous studies have reported the possibility of variation in run speed in the presence of attractants although it is unclear whether bacteria can deliberately modulate their swimming speeds in response to environmental cues or if the motor speeds are hardwired. By studying the detailed motion of cells in a uniform concentration of glucose and its non-metabolizable analogue, we show that changing concentrations may be accompanied by variation in the swimming speed. For a fixed run duration, cells exposed to the attractants achieved a higher peak-swimming speed after a tumble compared with that in plain motility buffer. Our experiments using the mutant strain lacking the Trg sensor show no change in swimming speed with varying concentrations of the non-metabolizable analogue, suggesting that sensing may play a role in the observed variation of swimming speed.

Armed Escorts: Dusky Dolphin (Lagenorhynchus obscurus) Interactions with Octopuses (Pinnoctopus cordiformis) in New Zealand

Between October 2011 and December 2013, three interactions between dusky dolphins (Lagenorhynchus obscurus) and common New Zealand octopuses (Pinnoctopus cordiformis) were witnessed and photographed off Kaikoura, New Zealand. In two interactions, an octopus was attached to a dusky dolphin; and in a third interaction, dusky dolphins appeared to be playing with an octopus. The attachment might have been an escape tactic for the octopuses. This is the first published record of interactions between dusky dolphins and octopuses in New Zealand. The few anecdotal reports of octopuses attached to dolphins are limited to species that commonly prey on octopuses. The evidence for dusky dolphins foraging on octopuses off Kaikoura is weak. The two species have different habitats but could come into initial contact through shallow nearshore dives performed by the dusky dolphins or by other species observed in the area, including New Zealand fur seals (Arctocephalus forsteri), humpback whales (Megaptera novaeangliae), or fishermen retrieving craypots. When the dusky dolphins encountered this unusual object in their environment, they may have initiated exploratory or playful behavior, which changed to distressed or defensive behavior upon the attachment of the octopuses. The erratic behaviors of the dolphins, including tail thrashes, rolling over, and rapid changes in swimming speed and direction, indicate they were disturbed by the presence of the affixed octopus. The dolphins did not perform acrobatic leaps, which are predicted to remove or reposition large “hitchhikers.”

The Effect of Swimsuit Resistance on Freestyle Swimming Race Time

It is known that swimming equipment (suit, cap and goggles) can affect the total resistance of a swimmer, and therefore impact the resulting swimming speed and race time. After the 2009 swimming world championships (WC) the international swimming federation (FINA) banned a specific type of full body suit, which resulted in an increase in race times for subsequent WC events. This study proposes that the 2009 suits provided a reduction in swimming resistance and aims to quantify this resistance reduction for male and female freestyle events. Due to the practical difficulties of testing a large sample of swimmers a simulation approach is adopted. To quantify the race time improvement that the 2009 suits provided, an equivalent 2009 “no-suit” dataset is created, incorporating the general trend of improving swimming performance over time, and compared to the actual 2009 times. A full race simulation is developed where the start, turn, underwater and surface swimming phases are captured. Independent resistance models are used for surface and underwater swimming; coupled with a leg propulsion model for underwater undulatory swimming and freestyle flutter kick, and a single element arm model to simulate freestyle arm propulsion. A validation is performed to ensure the simulation captures the change in swimming speed with changes to resistance and is found to be within 5% of reality. Race times for an equivalent “no-suit” 2009 situation are simulated and the total resistance reduced to achieve the actual 2009 race times. An average resistance reduction of 4.8% provided by the 2009 suits is identified. A factor of 0.47 ± 10%, to convert resistance changes to freestyle race time changes is determined.

Brief Behavioral Response Threshold Level of a Harbor Porpoise (Phocoena phocoena) to an Impulsive Sound

Underwater impulsive sounds may affect the behavior of harbor porpoises within a certain distance from the sound source. To determine the 50% threshold received sound exposure level (SEL) of an impulsive sound that causes a brief behavioral response (a sudden change in swimming speed and/ or direction, similar to a startle response) in harbor porpoises, a male harbor porpoise was exposed once every 3 min to a single impulsive sound: a synthetic exponential pulse with a 5 ms time constant, reproduced by an underwater loudspeaker in a pool (resulting in a signal duration of 10 ms). The sound was transmitted at seven source levels, which were expected to cause brief responses in 10 to 90% of exposures. During each transmission, the harbor porpoise’s behavior was observed, and the presence or absence of a brief response was recorded. A 50% brief response rate was observed at a received SEL of 92 dB re 1 µPa2 s, and a zeroto-peak sound pressure level of 122 dB re 1 µPa. The present study suggests that a single impulsive sound as used in this study does not cause a brief response in harbor porpoises at SELs below around 65 dB re 1 µPa2 s. The duration and spectrum of impulsive sounds change with distance to the sound source, and such changes may affect the responses of wild harbor porpoises.

Swimming near deformable membranes at low Reynolds number

Microorganisms are rarely found in nature swimming freely in an unbounded fluid. Instead, they typically encounter other organisms, hard walls, or deformable boundaries, such as free interfaces or membranes. Hydrodynamic interactions between the swimmer and nearby objects lead to many interesting phenomena, such as changes in swimming speed, tendencies to accumulate or turn, and coordinated flagellar beating. Inspired by this class of problems, we investigate locomotion of microorganisms near deformable boundaries. We calculate the speed of an infinitely long swimmer close to a flexible surface separating two fluids; we also calculate the deformation and swimming speed of the flexible surface. When the viscosities on either side of the flexible interface differ, we find that fluid is pumped along or against the swimming direction, depending on which viscosity is greater.