Название | Diatom Gliding Motility |
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Автор произведения | Группа авторов |
Жанр | Биология |
Серия | |
Издательство | Биология |
Год выпуска | 0 |
isbn | 9781119526575 |
6 Chapter 6Figure 6.1 Low-temperature scanning electron micrographs of diatom life styles (clockwise from top left): Stalked, tube forming, adpressed, epipelic. (Images: Irvine Davidson, University of St Andrews.)Figure 6.2 Low temperature electron micrograph of the pathway of an epipelic diatom moving thorough fine silt (Bar marker = 10 um). (Image: Irvine Davidson, University of St Andrews.)Figure 6.3 Top: Change in environmental driver (pressure) dependent on the presence of a “stabilizing biofilm” or under “regular erosion.” Bottom: Low-temperature scanning electron micrograph of MPB biofilm structure. (Image: Irvine Davidson, University of St Andrews.)
7 Chapter 7Figure 7.1 Proposed model of the control of vertical migration by sediment-inhabiting benthic pennate diatoms, as responding to main directional environmental stimulus, light and gravity. The figure illustrates the variation with the time of day of the diatom biomass at the sediment surface on samples kept in the dark (closed circles) and exposed to constant low light (150 μmol m-2 s-1) during the subjective low tide period (open circles) (for more details, see [7.18]). Example of a day when the low tide takes place during the middle of the day. The gray horizontal plots represent the strength (bar thickness) of photo- and geotaxis, of negative and positive signal, along the day. (1) Upward migration starts before the beginning of the light period, driven by negative geotaxis. (2) Negative geotaxis ceases roughly at the time expected for start of the low tide light period: if no light is available at surface, the diatoms stop migrating upwards and the incipient biofilms start to disaggregate, due to random cell movement or weak positive geotaxis. (3) During light exposure, cell movements are controlled mainly by phototaxis, either positive (under low light intensities) or negative (under high light intensities). In the particular case of the data in the figure, positive phototaxis dominates, as samples were exposed to low intensity. (4) Anticipating the end of the light period, geotaxis becomes dominant over phototaxis, as cells begin to migrate downwards without any changes in incident illumination. Vertical gray areas represent periods of darkness. Vertical white area represents the period of light exposure (150 μmol m-2 s-1) of the light exposed samples.
8 Chapter 8Figures 8.1–8.13 LM images of Eunotia taxa in valve view (Figures 8.1–8.8) and girdle view, ventral-side up (Figures 8.9–8.11) to show variation in morphology and raphe shape and location (arrow in some images). (Figure 8.1 [8.28]) E. bilunaris (Ehrenb.) Souza – raphe recurved almost 180°. (Figure 8.2) E. serra Ehrenb. – raphe on valve face with slight curve toward apex. (Figure 8.3 [8.28]) E. areniverma Furey, Lowe et Johansen – raphe follows margin of apex from ventral to dorsal margin, and up onto dorsal mantle. (Figure 8.4 [8.28]). E. pectinalis var. ventricosa (Ehrenb.) Grunow (E. pectinalis var. ventralis (Ehrenb.) Hust. = synonym). (Figure 8.5) E. bigibba Kütz. – raphe with slight recurve. (Figure 8.6) E. incisa Smith ex. Gregory – raphe (not visible) only present on valve mantle (see Figure 8.17). (Figure 8.7) E. muscicola Krasske – raphe (not visible) on the valve face with slight recurve (see Figure 8.20). (Figure 8.8) Close up of valve apex and raphe of E. bilunaris in Figure 8.1. (Figure 8.9) E. bigibba and (Figure 8.10) E. tetraodon Ehrenb. – ventral-girdle view. Depth of valve only permits part of raphe to be in focus (on one plane) at a time. (Figure 8.11) Unknown valve in ventral-girdle view. Raphe almost all in focus. (Figure 8.12) Epiphytic cells of E. bilunaris (E) standing up on end from the mucilaginous sheath(s) of the cyanobacterium Hapalosiphon Nägeli ex Bornet et Flahault (Image credit R.L. Lowe). (Figure 8.13) SEM image of Eunotia on a bryophyte. For all images except for Figure 8.8: black scale bar = 10 μm. Figure 8.8: white scale bar = 5 μm. (Figures 8.1, 8.3, 8.4 originally published in Furey et al. [8.28] www.schweizerbart.de/journals/bibl_diatom).Figures 8.14–8.22 SEM images of Eunotia taxa to show variation in morphology, along with external and internal raphe (R) shape and location on the valve face and valve mantle, helictoglossa (h), shape, location, and internal expression of the rimoportula (r), and external expression of the rimoportula pore (rp). (Figure 8.14 [8.28]) E. areniverma – raphe follows margin of apex from ventral to dorsal margin, and up onto dorsal mantle. (Figure 8.15 [8.28]) E. areniverma – internal view of apex. Rimoportula located mid apex. (Figure 8.16 [8.28]) E. pectinalis var. ventricosa – external view showing path of raphe from mantle onto valve face with slight recurve. (Figure 8.17 [8.28]) E. incisca – raphe located completely on valve mantle. External expression of rimoportula. (Figure 8.18) E. bigibba – curve of raphe onto valve face with slight recurve. (Figure 8.19) E. serra – raphe on valve face with slight curve toward apex. (Figure 8.20) E. muscicola – curve of raphe onto valve face with a slight recurve and (Figure 8.21) internal view of valve apex with rimoportula located close to the helictoglossa. (Figure 8.22) E. serra – internal view of valve apex with rimoportula located closer to dorsal margin. Scale bars as shown. (Figures 8.14–8.17 originally published in Furey et al. [8.28] www.schweizerbart.de/journals/bibl_diatom). [8.38] [8.53] [8.66], though their position could be derived if a more complex raphe system became reduced (discussed by Kociolek [8.44]