Changes in the organization of the microfilamentous cortical cytoskeletal system during oral regeneration in Climacostomum virens (ciliate)

Abstract

Summary— With specific antibodies directed against non‐actin micrifilaments (NAMFs), it was possible to determine the spatial distribution of these cytoskeletal elements within the cell cortex of the ciliate Climacostomum virens by immunofluorescence. In the somatic areas, the antibodies allowed to vizualize a more or less continuous layer spanning the whole cell surface with a higher amount of filaments just beneath the ciliary rows. In the buccal region the NAMF system forms bundles running parallel to the ciliary clusters termed the membranelles. The same procedure was used on cells treated with 1 M urea, an agent which induces the release of the oral apparatus followed by a complete regeneration of this part of the cell body. Such an approach completed by an electron microscopy study allowed us to describe the dynamic of NAMFs in the region where new ciliary membranelles will organize from a few somatic kinetics. We observed that in this region, the NAMF system undergoes a desorganization‐reorganization cycle during oral apparatus regeneration. This cycle may be related to the destabilisation of the cortex which allows kinetosome proliferation and to its restabilisation which corresponds to the definitive positioning of the new kinetosomes. Consequently, regeneration of C virens's oral apparatus seems to be a good model for studying relations between cortical NAMF cytoskeleton, positioning of kinetosomes, and cortical stabilisation.

Centrin-like filaments in the cytopharyngeal apparatus of the ciliatesNassula andFurgasonia: Evidence for a relationship with microtubular structures

“…The discriminative properties of our antibodies could well reflect a similar dichotomy between centrins involved in filamentous contractile structures and kinetosomal forms of the protein. Consistent with this hypothesis, centrins previously characterized by mAb A69 and anti-EEB antibody have been found in myonemes and/or related contractile fiber systems [Vigues et al, 1984;Vigues and Grolière, 1985;Garreau de Loubresse et al, 1988;Hulays et al, 1991;David and Vigues, 1994] and were absent from kinetosomes as shown in the present study. With the increasing availability of centrin genes in ciliates, it would be interesting to know where the epitopes reside on nonkinetosomal forms of centrin since this might provide further insight into the molecular mechanisms that contribute to the functional diversity of these proteins in a singled-cell organism.…”