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Egestion of carmine particle-containing food vacuoles from the cytoproct of Tetrahymena pyriformis has been analyzed by high-speed cinemicrography. The vacuole may enter into position in the cytoproct approximately 7 sec before ejection, and forms a distinct bulge beyond the outline of the cell surface for over 2 sec prior to ejection. The ejection process itself requires 20-80 msec.

Monstrous Tetrahymena pyriformis strain GL may be isolated after exposure of normal cells to numerous heat shocks, to flattening on agar or gelatin plates, or to viscous solutions of methyl cellouse. It is shown that in some cases the abnormalities are inherited and that this results in clones where the cells are different from each other and have various abnormalities with respect to cortical pattern, swimming and feeding behavior, and generation time. Furthermore, it is shown that these cells are produced rather than selected by the experimental treatments. Evidence is presented that growth without division is important for production of the abnormal organisms. The basis of the inheritance of the abnormalities is discussed.

Guanylate cyclase activity decreased during the division phase of heat-shock synchronized Tetrahymena pyriformis, strain GL. However, when Ca2+ was removed by EGTA to negate the effects of the Ca2+-binding protein (calmodulin), which is required for the full activity of guanylate cyclase in this organism, no significant change in the enzymatic activity was observed throughout the cell cycle. On the other hand, the reduced guanylate cyclase activity at division phase was associated with a decreased level of calmodulin content. These results suggest that fluctuations in guanylate cyclase activity during the cell cycle would be dependent on the concentration of calmodulin.

Progress in ciliatology and in allied fields may demystify ciliate phylogenetics. Concentration on hymenostomes (mainly Tetrahymena and Paramecium) may have obscured directional features of ciliate physiology in phylogenetic problems. Therefore, means are suggested for "domesticating" the presumptively primitive, predominantly marine, sand-dwelling gymnostomes having nondividing macronuclei. The prize quarry is the marine psammophile Stephanopogon whose homokaryotic condition may mark it as a living fossil. Eventual axenic cultivation of these "primitive" ciliates may be aided by use as food of easily grown photosynthetic prokaryotes, some isolated from the marine sulfuretum or adjacent aerobic muds and sands where "karyorelictid" ciliates flourish.

Schizopyrenus russelli, a free-living soil ameba, grows and encysts in the presence of bacteria. The encystment occurs with decline in the division rate. This is accompanied by incorporation of [U-14C] glucose into cyst cellulose. The degree of multiplication (but not of encystment) is a function of bacterial concentration. Berenil, a trypanocidal drug, while allowing excystment, completely inhibited multiplication of emerged amebae and their encystment. Addition of this drug after 24 hr, when amebae had gone into a phase of active division failed to check encystment, although it still inhibited further multiplication of the amebae. The findings suggest that a phase of cell division may be a prerequisite for encystment.

Cells of the ciliate Tetrahymena pyriformis GL overproduce and accumulate massive quantities of the heme intermediate, protoporphyrin IX. Protoporphyrin is localized intracellularly in discrete membranous compartments. The amount of porphyrin stored in the cell changes dramatically as cells progress through the growth cycle. Porphyrin overproduction is stimulated by delta-aminolevulinic acid, but only during the mid-stationary phase. Overproduction of protoporphyrin IX apparently results from an increase, late in the growth cycle, of activities subsequent to delta-aminolevulinic acid synthetase. Feedback inhibition in the pathway by accumulated protoporphyrin IX does not occur. The presence of Co2+ completely inhibits accumulation of protoporphyrin IX in a manner reversed by delta-aminolevulinic acid. Sn4+ stimulates protoporphyrin IX accumulation in the culture.

Synthesis of RNA in the macronucleus and appearance of RNA in the cytoplasm were studied in heat synchronized Tetrahymena pyriformis GL and compared to those found under conditions of logarithmic growth (28 C) and during heat shocks (34 C). In macronuclei of logarithmically growing cells precursors were processed to 2 rRNA species (25S and 17S). In addition, another RNA (15S), more homogeneous than the RNA (8-15S) in the cytoplasm, was observed in the macronucleus. Both 17S and 25S rRNA species were found in the cytoplasm, 17S rRNA appearing more rapidly than 25S rRNA. Synthesis of rRNA was suppressed at 34 C in cells subjected to heat synchronization; 8-15S RNA synthesis appeared to be inhibited to a lesser extent. During the time preceding the first synchronized division, the synthesis of rRNAs in the macronucleus slowly recovered. Early in the cycle, almost no newly synthesized rRNAs were extracted. By 30 min after the last heat shock (EH), most of the RNA synthesized was not identified as rRNA. By 60 min after EH, the pattern of RNA synthesis had not returned to that observed in logarithmically growing cells.

Transformation of Tetrahymena pyriformis to a rapid-swimming (presumably dispersal) form can be induced by washing cells and suspending them in distilled H2O, Dryl's solution or 10 mM Tris. Transformation is possible with high efficiency in mass cultures of axenically grown cells within approximately 5 h at 30 C. The radically different phenotype produced during transformation is characterized by a more elongate body form, increased numbers of somatic basal bodies and cilia, a long caudal cilium and oral membranelles positioned beneath the cell surface. DNA quantities characteristic of G1, S, and G2 cells are found in these transformed ciliates, suggesting that achievement of a particular stage in the DNA-division cycle is not a prerequisite for transformation. Preliminary observations on cells belonging to syngens 2-12 indicate that they also have a capacity to form a caudal cilium, but that the amicronucleate strain GL-C does not. Possible relevance of the transformed phenotype for taxonomy of Tetrahymena is discussed.