Isolation and partial characterization of macro- and micronuclei from Paramecium aurella

A method was developed for the isolation of macro- and micronuclei from Paramecium aurelia. This method utilized ionic and nonionic detergents to rupture the intact cells, calcium ions and spermidine were employed to protect the nuclei, and the nuclei were purified by centrifugation. Macronuclei consisted of 22% DNA, 10% RNA, and 68% protein. Micronuclei were composed of 9% DNA, 11% RNA, and 80% protein. DNA from both macro- and micronuclei had a density of 1.687 g/cc in CsCl and 1.417 g/cc in Cs(2)SO(4). These values corresponded to G + C content of about 23%. The RNA of macronuclei was examined by gel electrophoresis, and two high molecular weight species were identified having molecular Weights of 1.3 x 10(6) and 2.8 x 10(6) daltons. Three syngens were studied, and in each case the conditions for isolation of the nuclei were the same and no differences were observed in the properties of the nuclei.

Polyamine stimulation of nucleic acid synthesis in an uninfected and phage-infected polyamine auxotroph of Escherichia coli K12 (arginine-agmatine ureohydrolase-putrescine-spermidine-lysine-cadaverine)

The addition of arginine to cultures of Escherichia coli K12 deficient in agmatine ureohydrolase (EC 3.5.3.7) results in polyamine depletion and a striking inhibition of nucleic acid accumulation and growth. The omission of lysine from these cultures leads to a further decrease in growth rate and nucleic acid synthesis. In arginine-inhibited cells the addition of putrescine or spermidine, in the presence or absence of lysine, restores the control rate of growth and nucleic acid accumulation. Under the same conditions of arginine inhibition in the absence of lysine, the addition of cadeverine alone stimulates growth rate and RNA synthesis. The addition of lysine to polyamine-depleted cultures results in cadaverine production and in the appearance of a new spermidine analogue, containing lysine carbon. The new compound has been identified as N-3-aminopropyl-1,5-diaminopentane. Infection of this arginine-inhibited, polyamine-depleted mutant with T(4)D results in markedly decreased amounts of DNA accumulation, as compared to infected cells uninhibited by arginine. Supplementation of arginine-inhibited infected cells by putrescine or spermidine restores DNA synthesis to the uninhibited level.

Protein synthesis by cell-free extracts of Proteus vulgaris

A cell-free protein-synthesizing system from Proteus vulgaris was developed and characterized. Initially, a very low activity was found to occur; it was shown to be due to a deficiency in the endogenous transfer ribonucleic acid (tRNA) content of the cell extracts. When tRNA was added to the polyuridylic acid (poly U) directed system, incorporation of 14C-phenylalanine into polypeptide readily occurred. This incorporation was dependent on ribosomes and supernatant fraction and the optimum concentrations of the various components of the system were found to be as follows: 120 μg/ml tRNA, 30 mM magnesium, 0.5 mM spermidine, 60 mM potassium, 50 mM adenosine triphosphate (ATP), 5 mM guanosine triphosphate (GTP), 0.03 mM cytosine triphosphate (CTP) and uridine triphosphate (UTP), 5 mM phosphoenolpyruvate (PEP), 50 μg/ml poly U, and 30 mM 2-mercaptoethanol.

Mescaline-induced changes of brain-cortex ribosomes. Role of sperimidine in counteracting the destabilizing effect of mescaline of brain-cortex ribosomes

1. The effect of spermidine on the mescaline-induced changes of brain-cortex ribosomes was studied by adding spermidine during the treatment of goat brain-cortex slices with mescaline. 2. Mescaline treatment of brain-cortex slices removed a portion of the endogenous spermidine from ribosomes and this removal was significantly prevented when spermidine was present during mescaline treatment. 3. Spermidine present during mescaline treatment of brain-cortex slices counteracted, to some extent, the destabilizing effect of mescaline on ribosomes with respect to heat denaturation. 4. Mescaline treatment of brain-cortex slices made ribosomes more susceptible to breakdown, releasing protein and RNA, and resulting in loss of ribosomal enzymic activities. However, spermidine present during mescaline treatment counteracted moderately the mescaline-induced ribosomal susceptibility to breakdown and ribosomal loss of enzymic activities. 5. Ribosomes of mescaline-treated cortex slices were rapidly degraded by ribonuclease and trypsin. However, if spermidine was present during mescaline treatment of brain-cortex slices the rates of degradation diminished.