Except for the recent report of Friedkin on pyrimidine nucleoside phosphorylase (2) and several papers from this laboratory dealing with ribonuclease and deoxyribonuclease (3, 4), little information is available concerning the occurrence of nucleolytic and nucleosynthetic enzymes in the ciliated protozoan, Tetrahymena pyrif0rmis.l This is in contrast to a number of studies carried out on the pu...

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Frayed cilia from Tetrahymena pyriformis have been examined in the electron microscope using both uranyl acetate and phosphotungstic acid as negative stains. Observations on the central microtubules show that one member of the pair exhibits two rows of short projections. These are about 18 nm long, and are spaced longitudinally at 16-nm intervals. In many specimens the projections are separated...

After treatment with nitrosoguanidine a mutation to temperature sensitivity was obtained in Tetrahymena pyriformis, syngen 1. The trait is controlled by a recessive allele, ts, at a locus linked to serotype locus T. I S is completely recessive, unlike any other allele studied in this organism, and the heterozygotes do not show vegetative assortment. The cross which revealed the linkage of ts an...

New antibiotics, macbecins I and II, have been found in the culture fluid of an actinomycete, which has the following properties: delayed fragmentation of vegetative mycelia, formation of coremia on solid media, the occurrence of meso-diaminopimelic acid in the cell wall, lysozyme resistance, and guanine-cytosine content of 71 +/- 1 mol%. The organism has been designated Nocardia sp. No. C-1491...

The unicellular Tetrahymena pyriformis contains digoxin-like materials (digoxin, digitoxin, digoxigenin). The effect of two aminoacid-type hormones (histamine and serotonin) and a peptide hormone (insulin) was studied on the level of the hormone-like steroid, digoxin, in the concentrations of 10 and 10 by using immunocytochemistry and flow cytometric and confocal microscopic analysis. Each horm...