The presence of cyclic AMP, and its effects on oral regeneration and in situ ciliary regeneration in stentor coeruleus

The Journal of Protozoology

1984

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Regenerating Stentor, exposed to the plant lectin phytohemagglutinin, are significantly delayed in completing oral regeneration. All of the delays are restricted to the earliest stages of regeneration prior to stage 3. The effects of phytohemagglutinin are reversible once the drug is removed. The addition of the presumed sugar receptor for phytohemagglutinin, N-acetylgalactosamine, at the start of oral regeneration could not reverse the effects of phytohemagglutinin, but the addition of excess (10 mM) extracellular calcium could. When the addition of the excess calcium was delayed for various times after phytohemagglutinin exposure, the effectiveness of the calcium in reversing the phytohemagglutinin-induced delays was reduced. Based on the mechanism of action of PHA in other cells, these results suggest that membrane proteins may be involved in controlling oral regeneration, possibly through mechanisms involving Cat+.PON the loss of its oral feeding apparatus, the ciliate Sten-

Section: Discussionsupporting

confidence: 52%

Phytohemagglutinin Induces Delays in Oral Regeneration in the Ciliate Stentor coeruleus1

The Journal of Protozoology

1984

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“…In almost all cases the presence of excess extracellular calcium can negate the effects of a particular agent on oral regeneration, suggesting the necessity of extracellular calcium for normal oral regeneration. However, the fact that the removal of extracellular calcium alone does not affect oral regeneration complicates this conclusion (Maloney and Burchill, 1977). Still, the implication of the results with Con A and PHA, as well as some other membrane active agents, is that calcium ions have some connection with the action of such agents.…”

Section: Discussionmentioning

confidence: 99%

“…Culture methods Stentor were cultured as described previously (Maloney and Burchill, 1977). Basically cells were grown in 2-3-quart Pyrex baking dishes containing a synthetic salt solution composed of 0.55 mM CaC12, 0.15 mM MgS04, 0.75 mM NaC03, and 0.33 mM KHCO3, with the pH adjusted to 7.5 with HC1.…”

Section: Methodsmentioning

confidence: 99%

Concanavalin a inhibits oral regeneration in Stentor coeruleus through a mechanism involving binding to the cell surface

Journal Cellular Physiology

1986

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Concanavalin A (Con A) has been shown to induce delays in oral regeneration in the ciliate Stentor coeruleus. Associated with the delayed oral regeneration is a shedding of the cell's extracellular pellicle with the loss of some pigment granules. It is shown that the delays in oral regeneration are not the result of the pigment shedding. The delays are localized in the earliest stages of oral regeneration prior to stage 4. The delays caused by Con A are completely reversible by the addition of 2 mg/ml alpha-D-methyl mannoside either at the time of Con A exposure or 5 min later. Con A clearly binds to the cell surface as shown by the binding of FITC-Con A and its reversal by alpha-methyl mannoside. Crosslinking of Con A receptor molecules may be responsible for the effects of Con A since succinyl Con A, which does not crosslink these receptors, has no effect on oral regeneration even at double the Con A concentration. Calcium ions are also implicated in the action of Con A because an excess of extracellular calcium (10 mM) completely eliminates the Con A delays when added simultaneously with Con A. Examination of the minimum extracellular calcium concentration required for this effect showed that 2 mM calcium can reverse most of the delays but that 5 mM is necessary to completely reverse the delays caused by Con A. If the addition of calcium is delayed for various times after Con A addition, the extracellular calcium is progressively less effective in reversing the Con A delays.

“…Stentor coeruleus was originally obtained from a pond on the Butler University campus and has been cultured in the laboratory since that time as described previously (Maloney and Burchill 1977). Briefly, cells were cultured in Pyrex baking dishes in a synthetic salt solution containing 0.55 mM CaCl 2 , 0.15 mM MgSO 4 , 0.75 mM Na 2 CO 3 , and 0.33 mM KHCO 3 made up in deionized water, with the pH adjusted to 7.5 with HCl.…”

Section: Methodsmentioning

confidence: 99%

Identification and Localization of a Protein Immunologically Related to Caltractin (Centrin) in the Myonemes and Membranelles of the Heterotrich Ciliate Stentor coeruleus

J Eukaryotic Microbiology

McDANIEL

Locknar

et al. 2005

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The contractile properties of the myonemes of Stentor are very similar to caltractin (centrin)-containing fibers of other organisms. We investigated whether the calcium-binding protein caltractin was present in Stentor by using three different antibodies to caltractin or caltractin-related proteins, in conjunction with immunofluorescence microscopy and protein blotting. Immunofluorescence demonstrated that a protein immunologically similar to caltractin is present in the myonemes and in the bases of the membranelles of Stentor. The localization to the myonemes is observed in intact cells, osmotically lysed cells, and isolated cortices. Double-label immunofluorescence with anti-alpha-tubulin and anti-caltractin antibodies showed that the fluorescence in the myonemes was not in the overlying Km fibers. The myonemes in the posterior one-third of the cell appear as thick fibers with no cross-bridging. They become thinner as they approach the anterior end of the cell and show extensive cross-bridging here. Staining in the bases of the membranelles shows a distinct comma-like immunofluorescence pattern similar to that seen with protargol-stained cells and SEM views of the membranellar band reported by others. Western blots demonstrated that the caltractin-like protein in Stentor has an apparent molecular weight of 23 kDa compared with the 20-kDa protein from Chlamydomonas and is a calcium-binding protein.