Swimming cells

Swimming cells have a single nucleus and two flagella inserted into a minute papilla at the anterior end of the cell the cell wall is thin. Most of the cell volume is occupied by one or more grass-green chloroplasts. In the most frequently used species, C. reinhardtii, only one cup-shaped chloro-plast is present one or more pyrenoids are present within the chloroplast starch grains surround the pyrenoid. 

Standard rRNA molecular phylogeny (Woese, 1987 Barnes et al, 1996 Stetter, 1996 Pace, 1997) implies the antiquity of hyperthermophile organisms. Though there has been much dispute about the rRNA interpretation, there is some consensus that, whether or not it is the very most ancient, life around hot-water vents is certainly of great antiquity. The implication is that by mid-Archean, hyperthermophile habitats around hot vents were populated by microbial mats, and the waters around hot vents were occupied by free-swimming cells. Mesophile prephotosynthetic plankton probably existed in the open seas, and, distal to the thermophile life in the surroundings of vents, the mesophile habitats further from the hot springs were also occupied. 

Figure 10. Experimental setup of grayscale OET for the alignment of swimming cells.

The recorded images of swimming cells are analyzed using the EVIOOO computerized (66) cell-tracking system to extract the time-dependent reversal frequency of the cells (Fig. 5 see for example ref. 67). 

Visualization of functional flagella + + + The only technique that enables visualization of rotating flagella on a swimming cell not in common use [116, 390, 452, 750]... 

Trachtenberg, S., Gilad, R. and Geffen, N. (2003). The bacterial linear motor of Spiroplasma melliferum BC3 from single molecules to swimming cells. Mol. Microbiol. 47, 671—697. 

This approach involves determination of the extent to which spermatozoa can migrate through a membrane (e.g., a Nucleopore membrane with 5 xm pore size). This extent correlates primarily with the fraction of fast and straight-swimming cells in the sperm sample and with the sperm progressive velocity [68]. 

Laser Doppler spectroscopy has been used to measure the statistically averaged properties of swimming cell populations. A bibliography on this topic can be found in Ascoli et al. (1978a). 

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