ISSN:
1615-6110
Keywords:
Algae
;
Desmidiaceae
;
Micrasterias
;
Lateral motion
;
microtubules
;
microfilaments
;
secondary wall microfibrils
;
preprophase band
;
nucleus position
;
septum
;
morphogenesis
;
membrane flows
;
chromatidal repulsion
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract On the basis of the “filament rotation model” that was elaborated for interpretations in cell motility, the lateral hydrodynamic effects of rotating filaments have been investigated by large-scale model experiments. Helices were rotated by small electric motors in a medium of high viscosity (honey or polyethyleneglycol). The observed effects, hitherto not investigated in detail by hydrodynamics, show some features that were attributed to the indefinable “formative power” or “vital force” of the past. The main effects generated by the rotating filaments are (1) flows and flow patterns with “impact zones” where flows collide, (2) regions of excessive pressure and negative pressure (“corner effect”) along a wall, (3) grooves and smoothly shaped ridges on a free fluid surface, and (4) “rolling” motions of freely hanging filaments. All effects and flow patterns depend on the appropriate distribution of rotating and counterrotating filaments. Each change of the rotational direction means a dramatic alteration. The application of the observed effects explains largely the function of the microtubule/microfilament hoops or helices during the cytokinesis of a plant cell. Interpretations or simulations are described for events as the formation of secondary wall thickenings, the orientation of their microfibrils, the motion of the preprophase band microtubules, the formation of the phragmosome, the migration, stationary position and shape of the preprophase nucleus, the girdle-, septum- and H-piece formation of cell walls in algae and some events of morphogenesis inMicrasterias. Further interpretations are related to the lateral flows and to invaginations of free cell membranes, to lateral filament motions, to the “right-left problem”, to the selfintertwining of filaments, to the rotation of a cell body by its flagellum, to the repulsion of chromatids during meiosis and to the tetragonal and hexagonal arrangement of filaments.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00940444
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