Electronic Resource
Oxford, UK
:
Blackwell Publishing Ltd
The @journal of eukaryotic microbiology
26 (1979), S. 0
ISSN:
1550-7408
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
SYNOPSIS. The helical coiling state of a glycerinated stalk in the family Vorticellidae had been regarded, without any evidence, as a reversible and completely equilibrated mechano-chemical system regulated by the external free Ca2+ concentration. Our present detailed observations of many individual stalks of glycerinated Vorticella convallaria revealed that the contraction-extension cycle of the helical stalks caused by increasing and decreasing free Ca2+ concentrations in the medium represents a kind of hysteresis. This phenomenon was observed in extensively glycerinated Vorticella in a medium of very low or physiological ionic strength, as well as in briefly glycerinated ciliates. With regard to the configurational change in various parts of a glycerinated stalk during the contraction-extension cycle, it was found that the initial bending of the stalk caused by increasing free Ca2+ concentration begins to take place near the zooid (head) while the initial reextension of the stalk with decreasing free Ca2+ concentration begins to take place near the zooid (head) while the initial reextension of the stalk with decreasing free Ca2+ concentration takes place simultaneously throughout the entire stalk. The Ca2+ threshold for complete reextension of the part of the stalk near the rootlet was found to be much higher than that near the zooid.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1550-7408.1979.tb04647.x
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