The Fine Structure of the Scopula‐Stalk Region of Vorticella convallaria

Abstract

We examined by SEM and TEM the stalk-scopular junction, the stalk, and stalk formation in Vorticella convallaria Linnaeus, 1767. The stalk sheath is anchored to the walls of the scopular lip and to the scopular cilia by thin fibrils. Experimental extraction of these fibrils weakens this junction enough to separate the stalk from the cell body. Telotrochs escape from the stalk by means of violent contractions of the cell body, accelerated beating of the trochal band cilia, and twisting of the cell body against the stalk. The edges of the scopular lip spread over the scopular cilia after escape and, in some cases, fuse to enclose the entire, aboral scopular surface in a cupola-like structure. The sessile cells contain fewer and smaller scopular granules than telotrochs. The presence of disintegrating scopular granules in the stalk matrix of some sessile cells suggests that they contain material which is secreted over a period of time to form the stalk. Eruptive formation of the initial adhesive pad and quick elongation of the distal part of the stalk suggests a rapid exocytosis of the larger, more numerous granules of the telotroch. The stalk sheath is formed of fibrils making up complete and incomplete compartments peripherally arranged along the major stalk axis.

Past‐President address: My journey in microbial ecology—footprints in the sand, island hopping, supply chains, and technology bridges

“…In the 1990's Howard Buhse, University of Illinois Chicago, and his students and colleagues pursued a serious interest in peritrich biology, emphasizing culturing techniques, telotroch formation, and DNA/RNA sequencing for spasmin proteins, which are related to proteins such as caltractin or centrins (University of Illinois Chicago, Faculty Profile, Howard E. Buhse, 2023). These collaborations resulted in several peritrich papers, as illustrated by their work on spasmin (Buhse Jr., 1998; DeBaufer et al., 2007; Maciejewski et al., 1999; Wibel et al., 1997).…”

“…One of Buhse's papers was co‐authored with John C. Clamp, North Carolina State University, Durham, NC, USA, who may be the most familiar peritrich biologist and ecologist for most of us (Wibel et al., 1997). One of the strongest proponents of the importance of studying peritrich ciliates.…”

Inhibition of Vorticetta microstoma Stalk Formation by Wheat Germ Agglutinin

“…The contractile portion of the vorticellid stalk is a filamentous organelle, the spasmoneme. The spasmoneme is bounded by three cellular membranes, an extracellular matrix, and an outer sheath (Allen 1973a, b; Buhse 1998; Wibel et al 1997). Stalk formation occurs during differentiation of a free‐swimming telotroch into a trophont.…”

“…Stalk formation occurs during differentiation of a free‐swimming telotroch into a trophont. Precursors of the stalk are apparently contained in dense granules that are located at the aboral or basal end of the telotroch (Amin and Buhse 1995; Wibel et al 1997). During the initial stage of attachment, a telotroch releases the dense granules by exocytosis.…”

“…During the initial stage of attachment, a telotroch releases the dense granules by exocytosis. The prestalk material seems to be discharged as a liquid that solidifies to form three structures, an adhesive pad, the stalk matrix, and stalk sheath (Amin and Buhse 1995; Buhse 1998; Wibel et al 1997). The stalk grows rapidly during the first hour after attachment and then continues more slowly for several hours (Vacchiano et al 1992).…”