The polyamines spermidine and spermine, and their precursor putrescine, are required for cell growth and cellular functions. The high levels of tissue polyamines are implicated in carcinogenesis. The major sources of exogenous polyamines are diet and intestinal luminal bacteria in gastrointestinal (GI) tissues. Both endocytic and solute carrier-dependent mechanisms have been described for polya...

We used mutant strains of Neurospora crassa to define the discretionary capacity of this species for excess putrescine. The spe-3 mutant, which accumulates putrescine internally, and the puu-1 mutant, which accumulates toxic levels of putrescine from the medium, both sequestered large excesses of putrescine in vacuoles. Concomitantly in puu-1, inorganic polyphosphate increased modestly and some...

We have reported that a single injection of 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3), the active form of vitamin D3, into vitamin D-deficient chicks produces a marked increase in the formation of duodenal putrescine by two pathways, one from ornithine and one from spermidine (Shinki, T., Takahashi, N., Kadofuku, T., Sato, T., and Suda, T. (1985) J. Biol. Chem. 260, 2185-2190). In this...

The effects of polyamines on the equilibrium between prokaryotic ribosomal subunits and 70 S ribosomes have been studied as a function of concentration of Mg2+ from 2.5 to 7.5 mM. Run-off ribosomes were obtained from Escherichia coli and were washed with buffered 1 M NH4C1. Spermidine at 1 mm favors association of subunits at all concentrations of Mg2+. Putrescine, at concentrations above 8 mM,...

Putrescine and spermidine uptake into carrot (Daucus carota L.) cells in culture was studied. The time course of uptake showed that the two polyamines were very quickly transported into the cells, reaching a maximum absorption within 1 minute. Increasing external polyamine concentrations up to 100 millimolar showed the existence of a biphasic system with different affinities at low and high pol...