Demonstration of cell-ricin interaction by electrophoretic light scattering.

Electrophoretic light scattering has been used to investigate the interaction of ricin, a vegetal toxin, with cells. This technique allowed measurements in the presence of free ligand and proved particularly useful for the study of a system with low affinity. The electrophoretic mobility of erythrocytes and oligodendrocytes was found equal to 2.08 x 10(-8) and 2.35 x 10(-8)m2s-1V-1, respectively. Upon ricin binding, these values decreased significantly. This change was related to the saturation of the binding sites. The specificity of the interaction was demonstrated by conducting the experiments in the presence of lactose. This specific inhibitor fully prevented the ricin-cell interaction.

Effect of gossypol on the morphology, motility and metabolism of a flagellated protist, Dunaliella bioculata.

Gossypol, a natural polyphenolic compound extracted from cotton seed, is known for its contraceptive properties on human beings and several other mammals. Gossypol induces disorders of spermatogenesis and inhibition of spermatozoal motility. To determine the molecular mechanism inhibiting the motility of cells, a flagellar protist (Dunaliella bioculata) has been chosen as a cellular model because of the heterogeneity of spermatozoa populations. Inhibition of cell motility by gossypol, measured by Laser Doppler Velocimetry, was observed with these cells at the same doses as for spermatozoa (30-50 mumoles/l). Mitochondria were found to be swollen in gossypol-treated algae and, in parallel, respiratory exchanges were decreased and photosynthesis was inhibited, although the chloroplast did not seem to be morphologically altered. A diminution of the essential ATP production was also found at the same doses. Therefore, the inhibition of flagellar motility could be explained by such a decrease. The rapid and parallel inhibition of respiration and photosynthesis at non-lethal concentrations leads us to the hypothesis of a common target involving both ubiquinone and plastoquinone, although this remains to be proved.

Structure of human cervical mucus from light scattering measurements.

Using laser light scattering, photon correlation and spectral analysis, it was shown that cervical mucus is a non-Newtonian Hydrogel with large meshes (approximately 5 microns). The experimental results are in agreement with a model of hydrogel with weak linkages and are definitely not compatible with a model of entangled macromolecules. Large oscillations, induced by both thermal and mechanical excitation, have been observed in this medium, probably due to its non-Newtonian character.

Control of ciliary beat by calcium: the effects of lindane, a potent insecticide.

The ciliary beat and cell motility of Dunaliella, a biflagellate unicellular green alga, have been studied by means of computer analysis of high-speed microcinematography and laser doppler velocimetry. Lindane was found rapidly to inhibit cell velocity in less than 5 min. and in a dose-related manner. After the initial 5-min. period, inhibition remained nearly stable for at least 3 hr. The waveform of the ciliary beat was not uniformly affected by lindane and only the effective stroke was greatly slowed down. The recovery stroke was not significantly modified, and the general form of the wave did not seem to be altered. Bending parameters automatically measured from high-speed movies showed that lindane induced a considerable lengthening of the initiation phase of wave propagation. Since lindane interacts specifically with calcium transport and can induce an increase in cytoplasmic calcium, the strong effect of lindane on ciliary beat is probably correlated with a modification of the calcium balance of the cell. These results support the hypothesis of a control of bend initiation by calcium.

New device for determination of cell electrophoretic mobility using doppler velocimetry.

Electrical phenomena of cell membranes may be examined by means of cell electrophoresis. Direct microscopic techniques are tedious, inaccurate and rarely reproducible. Therefore, the authors have developed a new device using Doppler velocimetry. After describing the apparatus, they propose two methods for testing treatment against electroosmosis and present the first biological applications on mixed populations of red cells.

Light scattering determination of various characteristic paramenters of spermatozoa motility in a serie of human sperm.

In this paper are presented the results obtained by the light scattering method of systematic study of different parameters characterizing spermatozoa motility in a series of human sperms, one hour and five hours after ejaculation. These results are relative to the concentration of spermatozoa, the percentage and the number of motile spermatozoa, the characteristic velocity and the velocity distributions. All these parameters are discussed one by one, the advantages (objectivity, small quantity of not diluted sperm, short time needed for measurements) and the limits of the light scattering method being pointed out. A comparison is made with results obtained by conventional methods. The fineness of this study shows that this method can be used with success in fundamental research as well as in a routine functional sperm study, allowing an objective and precise analysis of motility in a given population as a complex factor.