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

Abstract

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.

Con A Binds to the Membranellar and Somatic Cilia of Stentor and to the Developing Oral Primordium During Oral Regeneration1

“…In both organisms the cells are also immobilized by Con A ( I , 5); Stentor generally become motionless and settle to the bottom though they occasionally show some very slow forward swimming (10). Similar results were noted with Stentor treated with P H A (9).…”

“…Pellicle shedding is not a unique response to Con A and Phaseolus vulgaris agglutinin (PHA) exposure, but is rather a general response ofStentor to many reagents (1 6) but generally at reagent concentrations much higher than the lectin concentrations employed in this a n d other studies (9,10,16). Further, nothing quite like this shedding has been observed with other drugs that I have studied in the past.…”

“…The lectins Concanavalin A (Con A) and phytohemagglutinin (PHA) have been used to examine the role of glycosylated membrane proteins in oral regeneration (9,10). Both lectins inhibit oral regeneration in the same manner (9, 10) when present from the beginning of regeneration.…”

Lectin-binding glycoconjugates in Paramecium primaurelia : changes with cellular age and starvation

“…Therefore, lectins are employed in cytological studies of membrane structures, of the intracellular pathway of protein glycosylation, of membrane component maturation, and of changes occurring in glycoconjugates during differentiation, growth, and development (Sharon and Lis 1989). Lectins were also used in protozoa to study sugar involvement in oral regeneration (Maloney 1986(Maloney , 1988, intercellular recognition and conjugation (Frisch and Loyter 1977;Tsukii and Hiwatashi 1978;Lueken et al 1981;Watanabe et al 1981; Van Bell 1983;Millikin and Weiss 1984;Lueken and Oelgemöller 1985;Pape et al 1988; Wolfe and Feng 1988;Plümper et al 1995), secretory activity Haake-Bell and Plattner 1987), cell movement (Frisch et al 1976; Van-DenBrink and Kaneshiro 1983), and phagocytosis (Brown et al 1975;Scott and Hufnagel 1983). The presence and distribution of glycoconjugates on the outer surface of the plasma membrane and subcellular organelles (Golgi apparatus, nuclear membrane, food vacuoles, discoidal vesicles, lysosomes, and trichocysts) were studied in some species of Paramecium (P. tetraurelia, P. caudatum, and P. multimicronucleatum) tested in the logarithmic phase of growth (Suchard et al 1982;Allen et al 1988Allen et al , 1989.…”