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Hysteresis of Contraction‐Extension Cycle of Glycerinated Vorticella
Author(s) -
OCHIAI TSUTOMU,
ASAI HIROSHI,
FUKUI KEIJI
Publication year - 1979
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1979.tb04647.x
Subject(s) - stalk , zooid , biophysics , chemistry , contraction (grammar) , biology , anatomy , horticulture , endocrinology
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 Ca 2+ 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 Ca 2+ 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 Ca 2+ concentration begins to take place near the zooid (head) while the initial reextension of the stalk with decreasing free Ca 2+ concentration begins to take place near the zooid (head) while the initial reextension of the stalk with decreasing free Ca 2+ concentration takes place simultaneously throughout the entire stalk. The Ca 2+ threshold for complete reextension of the part of the stalk near the rootlet was found to be much higher than that near the zooid.