Stentor, Its Cell Biology and Development

Abstract

comprises a genus of freshwater protists that has long enthralled cell and developmental biologists. These organisms are large polyploid single cells that possess highly polarised and complex structures. Normally elongated in a trumpet‐like shape, cells also have the ability to contract their cell body, and do so in response to mechanical or light stimuli. Interestingly, this response is subject to habituation, meaning the cell can ‘learn’ after repeated exposure to ignore these stimuli and stay elongated. Perhaps the most remarkable characteristic of is the ability of these cells to fully regenerate after being cut in half, perfectly preserving the original cell structure. Numerous microscopic studies analysed the minute morphological details of regeneration, but for many decades, there were no tools available for molecular and genetic studies. However, recent developments should now allow researchers to probe the molecular details of regeneration in a single‐celled organism.

Key Concepts

  • Stentor coeruleus is a large and highly polarised single cell with complex cell biology.
  • Stentor cells exhibit a rapid contractile response in reaction to light and mechanical stimulation, but they can habituate to these stimuli over time.
  • Stentor cells possess the remarkable ability to fully regenerate themselves after being cut in half.

Keywords: Stentor coeruleus; ciliates; protists; regeneration; habituation

Figure 1. Diagram of an . cell. The frontal field, membranellar band and oral pouch comprise the oral apparatus at the anterior end of the cell, and the cell terminates in a holdfast at the posterior end. Extending longitudinally from the anterior to posterior end are ciliary rows, bordered by a dark pigmented cortical stripe on one side and a clear cortical stripe on the other. The pigmented stripes are graded in width, and the area where the wide stripes abut the thin stripes is the ramifying zone. The transcriptionally active polyploid macronucleus (blue) is a single continuous organelle that appears as a series of connected nodes and extends through most of the length of the cell. The micronucleus is not pictured but consists of multiple tiny organelles closely associated with the macronucleus.
Figure 2. Dynamic cell shape of cells. When swimming, cells tend to be around 0.5–1 mm long and exhibit an aquadynamic shape (large inset). When anchored, however, the cells can extend themselves to much greater lengths, even reaching closer to 3 mm, as shown in the cells in the background image. The cells also exhibit a contractile response upon mechanical or photo‐stimulation (small inset), in which the cell shape becomes much more rounded and length decreases to around 0.25 mm. Image is to scale.
Figure 3. Stages of cell division in . The first three stages show the development of the new oral primordium, where the new membranellar band will form. In stages 3 and 4, cilia begin to grow from the oral primordium, and in stage 5, it begins to curl as the new oral starts to form at the posterior end of the new band and the macronucleus begins to coalesce. In stage 6, the fission line appears, cutting across the cell's longitudinal striping. In stage 7, the fission line and new membranellar band migrate slightly posteriorly as the congealed macronucleus stretches between the two new daughter cells, and in stage 8, the fission line continues to constrict until fission occurs and cytokinesis is complete. Reproduced with permission from Tartar, 1958. © John Wiley & Sons.
Figure 4. Regeneration of anterior and posterior portions of . . Anterior fragments (a) are able to regenerate the holdfast rather quickly (b) and continue to increase in size afterwards (c). Posterior fragments (d), however, need to regenerate the oral apparatus which takes much longer. Around 5 h post‐surgery, the new membranellar band can be seen migrating towards the anterior pole (e), and by 8 h, the oral apparatus has fully reformed (f). The cell will then continue to grow over the next 48 h to reach its original size. Black arrows, membranellar bands.
Figure 5. Knockdown of Mob1 prevents normal regeneration of cut . When control cells have their anterior and posterior ends removed by a glass needle, the cell regenerates properly (a) but when Mob1 RNAi cells have their anterior and posterior ends removed, the cell fails to regenerate its proper shape over time (b) (see also Slabodnick et al., ).
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References

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Further Reading

Lynn D (2011) The Ciliated Protozoa, 3rd edn. New York: Springer.

Slabodnick M, Prevo B, Gross P, Sheung J and Marshall W (2013) Visualizing cytoplasmic flow during single‐cell wound healing in Stentor coeruleus. Journal of Visualized Experiments 82: e50848.

Wyers EJ, Peeke HVS and Herz MJ (1973) Behavioral Habituation in Invertebrates. In: Peeke HVS and Herz MJ, (eds). Habituation: Behavioral Studies, pp. 1–59. New York: Academic Press.

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How to Cite close
Reiff, Sarah B, and Marshall, Wallace F(Feb 2015) Stentor, Its Cell Biology and Development. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0025978]