Rotational and translational swimming of human spermatozoa: a dynamic laser light scattering study

The rotational swimming motion of human spermatozoa is evaluated from measurements of depolarized dynamic laser light scattering at zero angle. The analysis is based on a Maxwellian angular velocity distribution and yields a rotational frequency of about 4 Hz that is ascribed to the rotation of the sperm head. From comparison with the translational swimming motion, a propelling efficiency of about 10 micron per turn is deduced. This parameter describes the linkage between the rotational and translational swimming motion and is likely to be discriminatory in the analysis of physiological and pathological sperm motions.     

Quasi-elastic light-scattering studies of single skeletal muscle fibers.

Measurements were made of the intensity autocorrelation function, g(2)[tau], of light scattered from intact frog muscle fibers. During the tension plateau of an isometric tenanus, scattered field statistics were approximately Gaussian and intensity fluctuations were quasi-stationary. The half time, tau 1/2, for the decay of g(2)[tau] was typically 70 ms at a scattering angle of 30 degrees. The decay rate, 1/tau 1/2, of g(2)[tau] varied roughly linearly with the projection of the scattering vector on the fiber axis. 1/tau 1/2 was greater during the tension creep phase of tetani of highly stretched fibers, but was roughly independent of sarcomere length during the tension plateau. g(2)[tau] measured during rest or on diffraction pattern maxima during isometric contraction were flat with low amplitudes. These results are consistent with a model of a 200-mu m segment of an isometrically contracting fiber in which scattering material possesses relative axial velocities of 1-2 mu m/s accompanied by relative axial displacements greater than 0.1 mu m. The slow (1-2 mu m/s) motion of one portion of the fiber relative to another observed under the microscope (500X) during isometric contraction is consistent with the light-scattering results. Structural fluctuations on the scale of the myofibrillar sarcomere which may arise from asynchronous cycling of cross-bridges must involve relative axial velocities less than 3 mu m/s or relative axial displacements less than 0.05 mu m.     

Laser light-scattering studies of bull spermatozoa. I. Orientational effects.

Calculations based on the known dimensions of bull spermatozoa show that the scattered light intensity is strongly dependent upon the relative orientation of the particle to the incident beam. The magnitude of this effect of apparently much greater than for other systems where motility has been investigated by dynamic light scattering. The calculations show that the scattering source can be approximated by a small spinning mirror, and consequently the greatest light intensity at the detector results from cells swimming in a direction perpendicular to the scattering vector. The calculations are in substantial agreement with photographic observations, as well as direct measurements of the scattered intensity. Previous treatments of dynamic light scattering from swimming bull spermatozoa based on point scattering models are shown to be incorrect.     

Rotational and translational motions of human spermatozoa: angle dependence of dynamic laser light scattering

We have studied how the dynamic components of laser light scattered from human spermatozoa depend on the scattering angle. This was done by investigating the halfwidth of the intensity autocorrelation function. A model of the spermatozoa as freely rotating and translating linear objects was adequate to describe the scattered light. Rotational motions determined the halfwidth of the intensity autocorrelation function at very small scattering angles and contribution from translational motions was dominant at scattering angles larger than 20 degrees. The contribution from translational motions increased with increasing scattering angle. We found a nearly linear relationship between the translation speed and the rotation frequency. However, the ratio between the two properties varied more than expected from the methodological error. Therefore we introduced a propelling efficacy as a concept to describe the swimming efficiency. This property might contain important information about the swim characteristics.Abbreviations ACF Autocorrelation function - _1/2 halfwidth - RGD Rayleigh-Gans-Debye - SD Standard deviation Correspondence to: P. Thyberg     

Rotational and translational motion of troponin C.

Time resolved fluorescence anisotropy and sedimentation velocity has been used to study the rotational and translational hydrodynamic behavior of two mutants of chicken skeletal troponin C bearing a single tryptophan residue at position 78 or 154 in the metal-free-, metal-bound-, and troponin I peptide (residues 96-116 of troponin I)-ligated states. The fluorescence anisotropy data of both mutants were adequately described by two rotational correlation times, and these are compared with the theoretically expected values based on the rotational diffusion of an idealized dumbbell. These data imply that the motion of the N- and C-terminal domains of troponin C are independent. They also suggest that in the metal-free, calcium-saturated and calcium-saturated troponin I peptide-bound states, troponin C is elongated, having an axial ratio of 4-5. Calcium or magnesium binding to the high affinity sites alone reduces the axial ratio to approximately 3. However, with calcium bound to sites III and IV and in the presence of a 1:1 molar ratio of the troponin I peptide, troponin C is approximately spherical. The metal ion and troponin I peptide-induced length changes in troponin C may play a role in the mechanism by which the regulatory function of troponin C is effected.     

Quasi-elastic light-scattering studies of aqueous biliary lipid systems. Cholesterol solubilization and precipitation in model bile solutions

We have employed quasi-elastic light-scattering methods to characterize micellar aggregates and microprecipitates formed in aqueous solutions containing sodium taurocholate (TC), egg lecithin (L), and cholesterol (Ch). Particle size and polydispersity were studied as functions of Ch mole fraction (XCh = 0-15%), L/TC molar ratio (0-1.6), temperature (5-85 degrees C), and total lipid concentration (3 and 10 g/dL in 0.15 M NaCl). For XCh values below the established solubilization limits (XChmax) [Carey, M. C., & Small, D. M. (1978) J. Clin. Invest. 61, 998], added Ch has little influence on the size of simple TC micelles (type 1 systems), on the coexistence of simple and mixed TC-L micelles (type 2 systems), or on the growth of "mixed disc" TC-L micelles (type 3 systems). For supersaturated systems (XCh/XChmax greater than 1), 10 g/dL type 1 systems (L/TC = 0) exist as metastable micellar solutions even at XCh/XChmax = 5.3. Metastability is decreased in type 2 systems (0 less than L/TC less than 0.6), and "labile" microprecipitation occurs when XCh/XChmax exceeds approximately 1.6. In 10 g/dL mixtures, the microprecipitates initially range in size from 500 to 20000 A and later coalesce to form a buoyant macroscopic precipitate phase. In 3 g/dL mixtures, the microprecipitates are smaller (200-400 A) and remain as a stable, noncoalesced microdispersion. Transmission electron microscopy of the microprecipitates formed at both concentrations indicates a globular noncrystalline structure, and lipid analysis reveals the presence of cholesterol and lecithin in a molar ratio (Ch/L) of approximately 2/1, suggesting that the microprecipitates represent a metastable cholesterol-rich liquid-crystalline phase. In supersaturated type 3 systems (0.6 less than L/TC less than 2.0), the precipitate phase is a lecithin-rich liquid-crystalline phase which likewise coalesces in a 10 g/dL system but forms stable vesicle (liposomal) structures (600-800 A radius) in 3 g/dL systems. In conjunction with these experimental data, we present a quantitative thermodynamic analysis of Ch solubilization in model bile systems from which rigorous deductions of the free energy and enthalpy change for solubilization of cholesterol monohydrate in type 1 and type 2 systems are obtained. In addition, we employ homogeneous nucleation theory to analyze the origin of the metastable/labile limit in supersaturated systems and to deduce the interfacial tension between microprecipitates and solution. On the basis of these experimental data and theoretical analyses, we offer new hypotheses on the structure and physiology of bile and the pathogenesis of Ch gallstones. In particular, it is suggested that the "stable" microprecipitates observed in 3 g/dL type 2 systems may provide a secondary vehicle (in addition to micelles) for cholesterol transport in supersaturated hepatic bile.     

Methods of measuring swimming speed of spermatozoa.

Three basic approaches for determining the mean swimming speed of a suspension of microorganisms were compared, using bull and ram spermatozoa. Number fluctuation counting was performed automatically on a Quantimet 720 image analysing computer, the mean speed being obtained using 'probability after' statistics. The other two approaches were photomicrographic: number flux counting was performed on single photomicrographs; on the same photomicrographs, the mean speed was estimated from measurement of 'whole' and 'half' track lengths. These results were compared with each other and with the Quantimet results. The 'probability after' method was also compared, on additional samples, with cine-photomicrographic tracking. The mean speeds predicted by the 'probability after' method compared favourably with the other methods (range 68 mum/sec to 162 mum/sec). The results also suggested that, on single photomicrographs, measurement of 'half' track lengths or number flux counting were generally preferable to measurement of whole track lengths.     

Quasi-elastic light-scattering studies of conformational states of the H,K-ATPase. Intervesicular aggregation of gastric vesicles by disulfide cross-linking

The particle size of hog gastric vesicles which contain H,K-ATPase was measured by using the method of quasi-elastic light scattering. The size of control vesicles is homogeneous as judged from its low polydispersity index. When the vesicles were treated with copper(II) o-phenanthroline (CuP), intervesicular S-S cross-linking occurred as determined by the aggregated vesicle size. The aggregation to divesicle size occurred very quickly, within 30 s, and the extent of aggregation did not depend on the extent of inactivation if the inactivation was not more than about 30%. Blocking of SH groups by 5,5'-dithiobis(2-nitrobenzoic acid) in the presence of Mg2+ prevented CuP-induced vesicular aggregation but not inactivation, indicating that S-S cross-linking rather than enzyme inactivation is the primary cause of vesicular aggregation. The presence of Mg2+ was required for the occurrence of aggregation. Nucleotides such as ADP (K0.5 = 5 microM) and 5'-adenylyl imidodiphosphate (K0.5 = 50 microM) inhibited the aggregation induced by 50 microM CuP plus 2 mM Mg2+ in a dose-dependent manner. Furthermore, K+ antagonized the effects of nucleotides. The extent of aggregation increased as the pH decreased in the pH range 6.1-7.4. Virtually no cross-linking occurred at alkaline pH (e.g., pH 8-9). These data show that vesicular aggregation can be assumed to reflect the conformational state of the responsible SH group in the native enzyme.     

Motility analysis of circularly swimming bull spermatozoa by quasi-elastic light scattering and cinematography.

The Rayleigh-Gans-Debye approximation is used to predict the electric field autocorrelation functions of light scattered from circularly swimming bull spermatozoa. Using parameters determined from cinematography and modeling the cells as coated ellipsoids of semiaxes a = 0.5 micrometers, b = 2.3 micrometers, and c = 9.0 micrometers, we were able to obtain model spectra that mimic the data exactly. A coat is found to be a necessary attribute of the particle. It is also clear that these model functions at 15 degrees may be represented by the relatively simple function used before by Hallett et al. (1978) to fit data from circularly swimming cells, thus giving some physical meaning to these functional shapes. Because of this agreement the half-widths of experimental functions can now be interpreted in terms of an oscillatory frequency for the movement of the circularly swimming cell. The cinematographic results show a trend to chaotic behavior as the temperature of the sample is increased, with concomitant decrease in overall efficiency. This is manifested by a decrease in oscillatory frequency and translational speed.     

Observations on the hydrodynamics and swimming motions of mammalian spermatozoa

An asymptotic solution of the Stokes Flow equations for a self-propelling filament is presented. An explicit expression for the propulsive velocity is obtained for the case of an infinite filament undergoing small amplitude sinusoidal motions. The asymptotic solution is then used to obtain drag coefficients to be used in a simpler approximate analysis which can be applied to experimentally observed motions.     

Aerobic and anaerobic swimming speeds of spermatozoa investigated by twin beam laser velocimetry.

The motility of bovine and ovine spermatozoa has been studied under aerobic and anaerobic conditions, using a dual beam laser velocimeter. Cells swimming under aerobic conditions were found to be characterized by a translational swimming speed and a rotation rate that were approximately double those of cells swimming in an anaerobic environment. Both types of spermatozoa have been found to exhibit a sudden coordinated transition between fast and slow swimming states when the available oxygen is exhausted. This transition from aerobic to anaerobic swimming states has also been shown to be reversible. Studies of the duration of aerobic motility using the same apparatus have shown that the cells have a constant motile efficiency over the temperature range 32 degrees-42 degrees C.     

Dynamic light-scattering studies of DNA. I. The coupling of internal modes with anisotropic translational diffusion in congested solutions

A model for the coupling between internal modes, or molecular rotation, and anisotropic translational diffusion in congested solutions is proposed to account for the anomalously slow component that has appeared ubiquitously in reported autocorrelation functions of Rayleigh scattered light from solutions of DNA's with molecular weights greater than about 10⁷. The predicted existence of an anomalously slow mode in addition to a faster “normal” mode, as well as the predicted relative amplitudes of both fast and slow components, are qualitatively in agreement with the observations. For sufficiently long-wavelength fluctuations all of the amplitude appears in the slower mode, which then exhibits an appropriately averaged translational diffusion coefficient. In support of the model it is shown in the Appendix that nonideal central interactions between macromolecules are by themselves insufficient to generate isolated internal mode relaxation terms in the autocorrelation function, unless translational ordering of the macromolecules extends over the illuminated observation region.     

Rotational and translational movement features of the pelvis and thorax during adult human locomotion

The kinematics of the pelvis and thorax are important in gait studies since their movement patterns are closely related to gait efficiency and 'smoothness' of locomotion. The purpose of this study was to identify features of normal gait patterns for later comparisons with pathological and developmental gait patterns. A two camera SELSPOT system interfaced with an HP1000 minicomputer was used to obtain three-dimensional kinematic/temporal data for the pelvis and thorax. Data from treadmill walking of eight adults were used for within subject (at different speeds) analyses. The analyses revealed a very complex pattern with a set of breakpoints which was consistent over all subjects. Some features were invariant over a range of walking speeds although the total range of motion changed considerably.     

Rotational and translational water diffusion in the hemoglobin hydration shell: dielectric and proton nuclear relaxation measurements.

The dynamic properties of water in the hydration shell of hemoglobin have been studied by means of dielectric permittivity measurements and nuclear magnetic resonance spectroscopy. The temperature behavior of the complex permittivity of hemoglobin solutions has been measured at 3.02, 3.98, 8.59, and 10.80 GHz. At a temperature of 298 K the average rotational correlation time tau of water within a hydration shell of 0.5-nm thickness is determined from the activation parameters to be 68 +/- 10 ps, which is 8-fold the corresponding value of bulk water. Solvent proton magnetic relaxation induced by electron-nuclear dipole interaction between hemoglobin bound nitroxide spin labels and water protons is used to determine the translational diffusion coefficient D(T) of the hydration water. The temperature dependent relaxation behavior for Lamor frequencies between 3 and 90 MHz yields an average value D(298K) = (5 +/- 2) x 10(-10)m2 s-1, which is about one-fifth of the corresponding value of bulk water. The decrease of the water mobility in the hydration shell compared to the bulk is mainly due to an enhanced activation enthalpy.