Our aim was to test the hypothesis that the frequency of neuronal rhythm-generating networks is partly controlled by the size of the active premotor interneuron population. We have tested possible mechanisms for frequency changes in a population model of the Xenopus laevis embryo spinal rhythm-generating networks for swimming. After initiation ...

cAMP-dependent phosphorylation of a 29-kDa axonemal polypeptide (p29) increases the swimming speed of permeabilized Paramecium and in vitro translocation velocity of bovine brain microtubules over 22S dynein extracted from Paramecium axonemes. A quantitative relationship between microtubule translocation velocity and beat frequency is developed. We conclude that p29 acts as a ...

The motility characteristics of natural assemblages of coastal marine bacteria were examined. Initially, less than 10% of the bacteria were motile. A single addition of tryptic soy broth caused an increase in the motile fraction of cells but only after 7 to 12 h. Motility peaked at 15 to 30 ...

The heads of demembranated spermatozoa of the sea urchin Tripneustes gratilla, reactivated at different concentrations of ATP, were held by suction in the tip of a micropipette and vibrated laterally with respect to the head axis. This imposed vibration resulted in a stable rhythmic beating of the reactivated flagella that ...

Six minke whales (Balaenoptera acutorostrata) were instrumented with VHF-radio transmitters and four with sonic speed-depth transmitters off the west coast of northern Norway and Svalbard and followed within view for up to 24 h. During such periods their respiratory rate was continuously recorded and their energy expenditure estimated according to ...

The medical literature in pathology contains a surprising number of anecdotal reports of primary cilia, with authors often expressing some incredulity at finding such organelles. In this update of an earlier review, I will argue that primary cilia should by now be regarded as regular cell organelles, not some form ...

The velocity distribution of swimming micro-organisms depends on directional cues supplied by the environment. Directional swimming within a bounded space results in the accumulation of organisms near one or more surfaces. Gravity, gradients of chemical concentration and illumination affect the motile behaviour of individual swimmers. Concentrated populations of organisms scatter ...

The effect of halothane on human ciliated nasal epithelium was studied in vitro. Samples from 24 healthy adult volunteers were exposed to halothane in varying concentrations and cilia beat frequency was measured using the transmitted light technique. Mean cilia beat frequency was measured at 30-min intervals. There was a significant ...

Halobacterium salinarium swims alternately in both directions of its cell axis. The average time between two reversals of the swimming direction is modulated by light stimuli. It is a matter of dispute whether the sensitivity to attractant stimuli depends on the time of stimulation during an interval. This question is ...

Follicular fluid alters the physiology and behaviour of spermatozoa by increasing acrosome reaction, accelerating capacitation, attracting the spermatozoon and enhancing vigorous motion of the cell. The objective of this study was to characterize the factor(s) in human follicular fluid that causes vigorous spermatozoa motion. Follicular fluid and its fractions were ...

The delta psi of R. sphaeroides, grown under high light to reduce the levels of light-harvesting bacteriochlorophyll, was naturally manipulated using light intensity. The relationship between delta psi and the swimming speed of free swimming populations of cells was investigated. After de-energisation by incubation in the dark there was an ...

Rabbit spermatozoa developed motions that mimicked hyperactivated motility during incubation for 16-20 hours under capacitation conditions and in several other commonly used media. Sperm from some rabbits failed to acquire this type of motility, and sperm from others failed to survive the long incubation time. Four motility patterns developed during ...

This study was an examination of the dose response of the kinematics of human sperm motion to 1-min and 30-min incubations with the spermicide Nonoxynol-9 (N9). At concentrations resulting in only slight reductions in percentages of motile sperm (MOT), increasing N9 decreased the progressiveness of sperm motion (reflected in decreasing ...

We have investigated the effects of caffeine, pentoxifylline, and 2'-deoxyadenosine on the motion characteristics and longevity of domestic cat spermatozoa. Freshly collected or cryopreserved domestic cat epididymal sperm were incubated with 0.01-20 mM caffeine, pentoxifylline, or 2'-deoxyadenosine for 15 minutes at 23 degrees C. The percent motility (MOT), curvilinear velocity ...

The ciliate protozoa, Stentor and Paramecium, have been reported to escape from the bottom end of narrow capillary tubes into a larger volume of medium with increasing rapidity over the course of trials. This change in behavior has been considered an apparent example of associative learning. This decrease in escape ...

In the present work we measured in real time the metachronism and degree of correlation between beating cilia from cultured mucociliary epithelium. The method is based on simultaneous measurement of ciliary beat frequency, phase shifts, and correlation factors in two directions: parallel and perpendicular to the effective stroke direction (ESD). ...

The unicellular green alga (Chlamydomonas reinhardtii maintains sensitivity of its phototaxis response (alignment of swimming direction along the axis of a light beam) over several orders of magnitude of light intensities. It is widely accepted that the rotation of the swimming cell provides temporal comparisons of light intensities via periodic ...

1. In Xenopus embryos, the frequency of natural and fictive swimming usually drops slowly as swimming continues but can increase following stimulation of the skin or dimming of the illumination. We have investigated whether such increases are associated with an increase in the number of neurones active at higher frequencies. ...

During the 6 min-lasting "free-fall conditions" (4 x 10(-6) g) of the parabolic flight of a sounding rocket Paramecium aurelia cells showed an increase of 7.5 % in their mean swimming velocity. A detailed analysis revealed that the kinetic response was transient: after 3 min the velocity decreased to the ...

Pentoxifylline improves some motility characteristics of human spermatozoa, but the variability of response to this drug has not been clearly defined. We used computer-assisted sperm motion analysis to examine the in-vitro response of spermatozoa to pentoxifylline. Individuals (n = 31) with normal sperm counts were randomly selected and their spermatozoa ...

A general Boundary Element Method is presented and benchmarked with existing Slender Body Theory results and reflection solutions for the motion of spheres and slender bodies near plane boundaries. This method is used to model the swimming of a microorganism with a spherical cell body, propelled by a single rotating ...

A cell culture of Paramecium with a precise negative gravitaxis was exposed to 4 x l0(-6) g during a parabolic flight of a sounding rocket for 6 min. Computer image analysis revealed that without gravity stimulus the individual swimming paths remained straight. In addition, three reactions could be distinguished. For ...

In order to test various drugs and possibly hazardous compounds on living cells in vitro a system with human spermatozoa was employed. A population of human spermatozoa was transferred into a defined medium by a swim-up procedure or by separation on a Percoll gradient. Such a population is rather homogenous ...

Motion characteristics of epididymal sperm from domestic cats exhibiting a high (> 60%; normozoospermic; n = 21) or low (< 40%; teratozoospermic; n = 6) occurrence of structurally normal spermatozoa were correlated with morphology (MOR) using computer-assisted semen analysis (CASA). Mean values and standard errors for percent motility (MOT), curvilinear ...

This paper reviews an ultraweak luminescent response of selected biological systems (lower and higher plants, insects and spermatozoa) to certain kinds of detrimental mechanical, temperature, chemical and photochemical stress and to lethal factors. The enhancing effect of white light and formaldehyde on the ultraweak luminescence of yeast and spermatozoa cells ...

Digital image analysis and light microscopy were used to study and quantify the growth and behavior of two variants and selected flagellar mutants of Vibrio parahaemolyticus in glass flow cells under high- and low-viscosity conditions. The observations showed a series of surface-associated behaviors, including attachment, microcolony formation, migration, chemotactic movements, ...

The movement of normal human nasal cilia was analyzed. Ciliary beat was recorded by means of a phase-contrast microscope equipped with a photodetector. The electrical signal was analyzed as follows: i) a power spectrum was calculated in order to measure ciliary beat frequency (CBF), ii) the beat cycles were averaged ...

By comparing the time of the same distance swum with and without an added resistance, under the assumption of an equal power output in both cases, the drag of 73 top swimmers was estimated. The active drag Fr(a.d.) at maximal swimming velocities varied considerably across strokes and individuals. In the ...

The rotational movement of a spermatozoon around its longitudinal axis was investigated by two methods: by observing a spermatozoon attached vertically to a coverslip by the tip of its head, and by observing a spermatozoon freely swimming in a medium by means of 'double-focal microscopy', which yielded simultaneous images at ...

Tissues from the pharynx of five representative species of the protochordates (subphylum Tunicata, the three classes Ascidiacea, Thaliacea and Appendicularia, and subphylum Cephalochordata) were examined in both thin sections and freeze-fracture replicas. In all species, the stigmatal cilia of the branchial chamber are neatly arranged and move continuously to propel ...

Bacteria swim using the only rotary motor identified in biology. The membrane bound motor uses the gradient of protons set up across the cytoplasmic membrane to drive the rotation of a semi-rigid protein helix, the flagellum. Free-swimming bacteria randomly change direction every few seconds, but if a gradient is encountered ...

Essential performance-determining factors in front crawl swimming can be analysed within a biomechanical framework, in reference to the physiological basis of performance. These factors include: active drag forces, effective propulsive forces, propelling efficiency and power output. The success of a swimmer is determined by the ability to generate propulsive force, ...

Halobacterium halobium swims by rotating its polarly inserted flagellar bundle. The cells are attracted by green-to-orange light which they can use for photophosphorylation but flee damaging blue or ultraviolet light. It is generally believed that this kind of 'colour vision' is achieved by the combined action of two photoreceptor proteins, ...

Anomalies of centriolar derivatives were identified in ejaculates and testicular and tracheal biopsies of a sterile stallion, using light, scanning, and transmission electron microscopy. LM revealed that over half the sperm population had only a vestigial or no tail, while the rest had tails of variable length and shape. The ...

We have found ways to control in vitro fertilization in a ctenophore (Beroe ovata) for the first time. This is based on the existence of a partial block to self-fertilization at the time of gamete release which can be overcome by removal of the egg envelope. It has allowed us ...

The response of the mechanism initiating flagellar bends to imposed mechanical transients has been studied by holding the head of a sea urchin sperm in the tip of a sinusoidally vibrating micropipet and then displacing the micropipet laterally at a speed of up to 1.15 micron ms-1 for 1.5 beat ...

The CellSoft Motion Analysis System was used to study the changes in motion characteristics of rabbit sperm during incubation in a medium in which capacitation occurs. Sperm velocity reached a maximum after 1 hr of incubation and then declined linearly. The mean velocity at 5 hr was significantly higher than ...

In the present study the time course and spectral-amplitude distribution of hydrodynamic flow fields caused by moving fish, frogs, and crustaceans were investigated with the aid of laser-Doppler-anemometry. In the vicinity of a hovering fish sinusoidal water movements can be recorded whose velocity spectra peak below 10 Hz. Single strokes ...

The phototactic behavior of Chlamydomonas eugametos gametes and vis-à-vis pairs was quantitated using a fully automated, computer-controlled microvideo image analysis system. Two different mt- (mating type minus) and one mt+ (mating type plus) strain, together with the two combinations of pairs were studied. One mt- strain of dark-adapted gametes was ...

This study defines the effect of artificial surfactant on ciliary beat frequency. We employed guinea pig tracheal rings and a photomultiplier which allows in vitro measurement of ciliary beat frequency. The beat frequency without surfactant decreased continuously while surfactant caused a relative increase in beat frequency. The difference between the ...

Halobacterium halobium swims with a polarly inserted motor-driven flagellar bundle. The swimming direction of the cell can be reserved by switching the rotational sense of the bundle. The switch is under the control of photoreceptor and chemoreceptor proteins that act through a branched signal chain. The swimming behavior of the ...

The flagellar beat plane of live and reactivated sea-urchin sperm held by their heads in the tip of a vibrating micropipette will rotate along with the plane of the imposed vibration for up to 10 revolutions in either a clockwise or a counterclockwise direction. Subsequent cessation of the imposed vibration ...

Random and nonrandom factors associated with sample preparation and the automated analysis (CellSoft) of rat cauda epididymal sperm motion were studied. Random factors included inherent system variation at both the individual cell level and at the multiple cell level. Repeated analyses of identical tracks across grey level revealed a statistical ...

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 ...

Many bacteria swim by rotating thin helical filaments that extend into the external medium, as with common bacteria, or run beneath the outer membrane, as with spirochetes. Each filament is driven at its base by a motor that turns alternately clockwise and counterclockwise. The motor-filament complex is called a flagellum. ...

Within the approximate range of 30-80 Hz, the flagellar beat frequency of a sea urchin sperm held by its head in the tip of a micropipet is governed by the vibration frequency of the micropipet. We have imposed abrupt changes in flagellar beat frequency by changing the vibration frequency of ...

Bacteria such as Escherichia coli and Salmonella typhimurium swim by rotating their flagella, each of which consists of an external helical filament and a rotary motor embedded in the cell surface. The function of the flagellar motor has been examined mainly by tethering the flagellar filament to a glass slide ...

Two highly trained groups, competitive swimmers (N = 6) and triathletes (N = 5), were compared to evaluate the significance of the propelling efficiency as a performance determining factor in swimming. Using regression equations, the groups were compared at equal power input (1000 W). The groups did not differ in ...

Suspensions of seminal plasma-free human spermatozoa were prepared by swim-up from semen and studied using high magnification videomicrography after incubation under capacitating conditions for 1.5-2 h. Three subpopulations of capacitating spermatozoa showing different patterns of motility could be distinguished visually: forward progressive, transition phase, and hyperactivated motility. The purpose of ...

1. The effects of bradykinin, a potent inflammatory nanopeptide, on tracheal ciliary beat frequency in vivo were investigated using barbiturate-anaesthetized beagles. Tracheal ciliary beat frequency was measured using heterodyne mode correlation analysis laser light scattering, a technique that does not require surgical intervention. 2. Aerosolized 10(-5) M-bradykinin in 0.9% saline ...