Cell model contraction in the ciliate spirostomum

Abstract

As the species name indicates, the large heterotrichous ciliate Spirostomum umbiguum is characterized by a twisting contraction of the cell body that is easily triggered by various kinds of external stimuli. On the basis of morphological studies, contraction and extension of this organism have been considered to result from antagonistic actions of myoneme and microtubular ribbons. After many trials, we have succeeded in preparing cell models to examine induced contractions and extensions of the cell body. The contraction of this model was induced by increasing the free Ca2+ concentrationc even in the absence of Mg-ATP and was reversed by adding Mg-ATP without Ca2' . Using dynein ATPase inhibitors such as vanadate and ATP analogs, furthermore, the experiments revealed that the ATPase that generated the force between the two neighboring microtubular ribbons might be a dynein-like ATPase.

Reactivation of Ca2+‐dependent cytoplasmic contraction in permeabilized cell models of the heliozoon Echinosphaerium akamae

“…A large number of investigations have been made on the Ca 2ϩ -dependent contraction of the glycerinated stalk of vorticellid ciliates [Asai et al, 1978;Ochiai et al, 1979;Yokoyama and Asai, 1987] and Triton-extracted models of heterotrichous ciliates [Ishida and Shigenaka, 1988;Ishida et al, 1996]. They showed that such contractions occur in an all-or-none fashion [Katoh and Kikuyama, 1997;Moriyama et al, 1998].…”

Expanded phylogenetic analyses of the class Heterotrichea (Ciliophora, Postciliodesmatophora) using five molecular markers and morphological data

“…Gruberia is quite similar to Spirostomum, but they differ in relation to the mode of contraction and paroral infraciliature. Body contraction in Spirostomum is helical because of the presence of microtubular fibers forming a counterclockwise spiral from the anterior to the posterior end (Ishida and Shigenaka, 1988). In Gruberia, the contraction is longitudinal, i.e., along the antero-posterior axis of the body (Dragesco and Dragesco-Kernéis, 1986).…”

Morphology and 18S rDNA gene sequence of Spirostomum minus and Spirostomum teres (Ciliophora: Heterotrichea) from Rio de Janeiro, Brazil

“…Many authors state in their descriptions that Spirostomum species lack a paroral membrane (TUFFRAU 1967, REPAK & ISQUITH 1974, ISHIDA et al 1988. However, FERNANDEZ-LEBORANS (1985) …”

“…The name Spirostomum refers to the ability these ciliates have to contract in a spiral mode. This type of contraction is due to the presence of post-ciliary, sub-pellicular fibers that arise on the anterior end and spiral in a counterclockwise direction toward the posterior end of the body (ISHIDA et al 1988).…”