Diatom Gliding Motility. Группа авторов

cell #1. (c) a phase diagram of the data shown in b, velocity versus position. (d) comparison between changes of position for cell #2 relative to cell #1 (red) and sine wave (black dashed). The oscillation period in frame c is 62.56 seconds.

      11 Chapter 11Figure 11.1 Expansion of a cylindrical mucopolysaccharide fibril.Figure 11.2 Schematic drawing of the expanding fibril.Figure 11.3 Time dependence of the sound pressure p.Figure 11.4 Time dependence of the sound pressure p for different mass transfer coefficients k.Figure 11.5 Schematic drawing of a jar with diatoms.Figure 11.6 Raphid diatom (to our best knowledge), caught by FZ; Note the visibility of the chloroplasts inside the diatoms; the scale bars are estimated.Figure 11.7 Stones from underwater with golden-brown film on them, collected by FZ in Natschbach, Austria, on May 5, 2019.Figure 11.8 Comparison of diatom samples obtained with different methods; the scalebars are estimated.Figure 11.9 Setup of first measurements.Figure 11.10 Measurement of jar with diatoms (right), reference jar (left).Figure 11.11 Jars with diatoms and little glass balls.Figure 11.12 Spectrogram of measurement with diatoms.Figure 11.13 Averaged spectrum over the whole spectrogram (0.5 s – 3.5 s).Figure 11.14 Averaged spectrum over the range 2.75 s – 3 s.Figure 11.15 Averaged spectrum between 1 s – 1.5 s.Figure 11.16 Spectrogram of reference measurement.Figure 11.17 Averaged spectrum over whole spectrogram (0.5 s – 3.5 s).Figure 11.18 Averaged spectrum between 0.5 s – 0.65 s.Figure 11.19 Averaged spectrum between 1.85 s – 2 s.Figure 11.20 Averaged spectrum between 2.5 s – 3.0 s.

      12 Chapter 12Figure 12.1 Waves formed by the microfibrils. The waves for each half­raphe vary independently in frequency and intensity. Translation of labels: Sens de progression l’onde = Direction of wave progression; Chloroplastes = Chloroplasts, Noyau = Node; Diatomée en vue connective = Girdle view of diatom.Figure 12.2 Movements of the microfibrils after their shortening: Position 1: Microfibrils at rest; Position 2: rc, shortening of one of the two microfibrils; Position 3: The two microfibrils, bonded at the point of connection, slanted at an angle according to the value of the shortening. Translation of labels: Sens du mouvement des microfibrilles = Direction of microfibril movement; Point de liaison = Contact point; Base des microfibrilles = Microfibril base. Top: Variation of f as a function of rc. Bottom: General formula f = (e2 – rc2 + 2L. rc) / 2rc. Setting L = 1, f = (e2 – rc2 + 2rc)/2rc. Setting L = 1, e = rc, then f = 1 = L = 90°.Figure 12.3 The slope of myosin heads generates the sliding of the actin filaments which causes their shortening and the retraction of the microfibrils. Translation of labels: Phase de contraction des microfibrilles (raccourcissement relatif) = Microfibril contraction phase (relative shortening); Phase de repos = Resting phase; Génération d’impulsions par dépolarisation des charges électriques au niveau du plasmalème = Depolarization pulse generation by electric charges at the cell membrane level.Figure 12.4 Birth, growth and slope of the microfibrils in relation to the wave trains of contraction. At rest, there is expulsion of mucus. Translation of labels: Inclinaison et “coup de fouet” des microfibrilles = Tilt and “whiplash” of microfibrils; Expulsion du mucus = Expulsion of mucus; Redressement des microfibrilles = Recovery of microfibrils; Repos = Rest; Diatomée = Diatom; Train d’ondes de contraction = Contraction of wave train.Figure 12.5 Displacement of the diatom on a half­raphe with organic matter drive on another half­raphe. Translation of labels: Émission de mucus = Mucus emission; Matière organique entraînée = Attached organic material; Sens de progression l’onde = Direction of wave travel; Résidue de mucus = Residue mucus²; Sens du mouvement de la diatom = Direction of diatom movement.

      13 Chapter 13Figure 13.1 Appearance of Navicula sp. diatoms under an optical microscope. Cells are about 14 µm long [13.24].¹Figure 13.2 SEM Image of Navicula sp. in girdle band face (a) and the frustule view (b).²Figure 13.3 Pore array and pore structure on the frustule. (a-c) Meso-porous structure in the frustule, (d) nanoporous strucuture inside mesopores. AFM mapping of pores around ridge (e) and mesopores (f).³Figure 13.4 The bending ability of the diatom wall during the re-positioning process, scale bar is 5 μm. (a-c) The diatom indicated by the arrow attaches to the wall and the diatom on the right side is changing its orientation by rotating in situ, which the maximum bending angle is about 37 degrees in (b).Figure 13.5 Equipment for analyzing bending ability of diatoms. See text for description. (a) Experimental set up of electrode corrosion for preparing tungsten needles, (b) characterization of an as-prepared tungsten needle, (c) experiment set up of bending ability characterization inside the SEM equipped with a micromanipulator and a force sensor.⁴Figure 13.6 The relationship between bending deformation and stress of frustules. The scale bar is 5 μm. (a) original position, (b) bending deformation with an angle of 26 degree, (c) forces measured with deformation.Figure 13.7 Simplifying the frustule bending into a simple cantilever beam system.Figure 13.8 Classical Edgar model. See text for description of components.Figure 13.9 Pits found in the mucilage trails. Scale bar equals 2 μm.⁵Figure 13.10 Diatoms locomoting while raised at an angle of inclination.⁷Figure 13.11 Cross-section view of diatom locomotion, (a) normal locomotion, (b) inclined locomotion.Figure 13.12 The same diatom crawls along the raphe (a-b) and its girdle band (c-f) surfaces.⁸Figure 13.13 Diatoms crawl with the girdle band facing the substrate.Figure 13.14 The circular structures in the body of some locomoting diatom cells. (a-d) are serial captures of the same diatom while locomoting, which two circular structures were observed to move within the cell body at high-frequency vibration at the microscale.⁹Figure 13.15 Obscure circular structures in locomoting diatom cells. Circular structures could be observed in some diatoms (a) but not always could be found (b) even under LSCM.¹⁰Figure 13.16 F-actin (green) stained by FITC-Phalloidin. Red color is due to autofluorescence of the diatom chloroplasts. Scale bar equals 5 μm.¹¹Figure 3.17 Change of circular structures and space competition with chloroplasts of locomoting diatoms after encountering obstacles. (a-c) a diatom was approaching an obstacle, in which circular structures were clearly seen and chloroplasts was stained with red color. (d-f) Since the diatom can not move the obstacle, it chose to return and the circular structure was squeezing against the chloroplasts to get itself backward.Figure 13.18 Z-stack scanning of a diatom from bottom plane (Z axis coordinate is 1.82 μm) to top plane (Z axis coordinate is 7.60 μm), corresponding from (a) to (d).Figure 13.19 Mucilage trails under SEM, in which pits could be clearly seen in (b) and (c). Scale bars equal to 5 μm (a) and 1 μm (b, c).¹²Figure 13.20 EDAX of mucilage trails and silicon substrate.¹³Figure 13.21 Raman spectra of mucilage trail. SM denotes the spectra from secreted mucilage, while TM-1, TM-2, and TM-3 represent the spectra from three representative mucilage trials.Figure 13.22 Lattice map of adhesion of the mucilage trail.Figure 13.23 Topology of a piece of mucilage trail under AFM Scanning: (a) & (b) are two randomly selected sections.Figure 13.24 Typical AFM measurements in culture medium (a) and mucus (b).Figure 13.25 (a) Force curve against mucilage trails, (b) force curve against EPS.Figure 13.26 Schematic diagram of return process after contact between probe tip and wall. (a) A typical force curve against the trail mucilage, (b) a typical force curve against EPS.Figure 13.27 Schematic diagram of polymer morphology of the mucus (a) and the EPS (b).Figure 13.28 Function of the mucus.Figure 13.29 Scheme of a cycle of repeatable steps (a-e) when a diatom is locomoting to the right in VW model. Briefly, two circular structures alternately use actins as anchors and changing their positions inside the diatom thus generate forces to achieve the locomotion, please refer to the detail description in the text.Figure 13.30 The processes on the cell membrane of diatom contacting the frustule at the raphe.¹⁶Figure 13.31 Locomotion trajectory of several diatoms. Each number represents the trail of a separate diatom.Figure 13.32 Determination of locomotion angle for each step. Positions 1, 2, and 3 represent 3 consecutive positions observed for a motile cell. When diatoms reach position 2, 15 s after position 1, the path direction is defined from the center point of the cell at each time point. After the cell moved to position 3 after another 15 s, the angle of turning from position 2 to position 3 was defined as α, in which α > 0 was defined as turning in a clockwise direction as observed.Figure 13.33 Distribution of locomotion angle.Figure 13.34 Distribution of locomotion length.Figure 13.35 Histogram of locomoting rate of diatoms on different walls and the velocity distributions.Figure 13.36 Comparison of secretion amount of diatom mucus: (a) mucus (b) EPS. Scale bar in (a) 5 μm.¹⁸Figure 13.37 Diffusion and dissolution of diatom secretion.Figure 13.38 Comparison of simulation results (b) and measured results (a) of diatom locomotion trajectory.¹⁹Figure 13.39 Locomotion trajectories of diatoms under different perception