Measurement of cyclic 3',5'-adenosine monophosphate synthesis in growing Escherichia coli.

The net synthesis of cAMP by an adenine auxotroph of $\text{Escherichia coli}$ was measured by assaying the incorporation of tritium from [³H]-adenine into cyclic [³H] AMP during exponential growth. Synthesis of cAMP ceased abruptly when glucose was added to cells growing in glycerol and then recovered to an intermediate rate of synthesis after 0.5–1.0 generation. Cyclic AMP appeared to be synthesized from a precursor pool that turned over more rapidly than total cellular ATP. The rates of cAMP synthesis measured by this technique are compatible with the cellular levels of cAMP previously measured in this strain(3).     

Effect of cyclic 3',5'-adenosine monophosphate on the growth rate of Escherichia coli

Cyclic 3',5'-adenosine monophosphate (cAMP) inhibits the rate of Escherichia coli growth in media with glucose. When the exogenous nucleotide is added, the generation time and the lag phase become longer. These parameters decrease if cAMP is entirely absent from the cya- mutant as compared to the parent cya+ strain. The nucleotide exerts a low activity in media with glycerol. The action of cAMP is highly specific.     

Regulation of beta-galactosidase synthesis in Escherichia coli by exogenous cyclic 3',5'-adenosine monophosphate]

The effect of cyclic 3',5'-adenosine monophosphate (cAMP) on the rate of beta-galactosidase biosynthesis was studied in the cells of Escherichia coli M-17 growing in MPB and mineral media with glucose and maltose, i.e. under the conditions of various catabolite repression, as well as upon lac-operon induction by isopropyl-beta-D-galactopyranoside (IPGP). The stimulating action of exogenous cAMP was found only in a medium with salts and glucose. The induction by IPGP was highest during the growth in a medium with glucose and maltose. When the medium contained IPGP, cAMP accelerated the enzyme synthesis in all media, but only at the early growth phases, while cAMP eliminated the effect of IPGP at the stationary phase of growth. The regulation of beta-galactosidase biosynthesis by cAMP demonstrated for the first time that this effect depended on the physiological state of E. coli: the expression of catabolite-sensitive E. coli genes was subject to both positive and negative regulation in one and the same inducible system. The effect exerted by cAMP depended on the nature of a carbon source in the growth medium.     

Novel aspect of cyclic 3',5'-adenosine monophosphate synthesis in Escherichia coli 3000A1

A kinetic analysis of cyclic 3',5'-adenosine monophosphate (cAMP) synthesis in an adenine auxotroph of Escherichia coli 3000 was made by assaying the incorporation of [3H]adenine into cAMP during exponential growth. The rate of increase in intracellular [3H]cAMP was very slow (0.1-0.2 pmol/min/DU660). The steady state level was attained at about 40-min incubation after the addition of [3H]adenine, and was estimated to be 5 to 7 pmol/DU660. The rate and level of intracellular cAMP were scarcely affected by growth conditions, such as change of carbon source, whereas the excretion of cAMP into the medium began immediately after the addition of [3H]adenine, and continued at a rate of 5 to 7 pmol/min/DU660 in the glycerol medium. The excretion rate decreased to 1.4 pmol/min/DU660 in the presence of glucose. These results are inconsistent with the view that the excretion rate is dependent on the intracellular concentration of cAMP. Although the decreased rate of cAMP synthesis in the presence of glucose accounts for the permanent catabolite repression of inducible enzyme systems, no immediate depression in cAMP synthesis, which might account for the transient repression, was found after the addition of glucose.     

Effect of cyclic 3',5'-adenosine monophosphate on central neurons

In experiments on unanesthetized non-immobilized rabbits, unit responses in the cortex and thalamus to the cyclic 3',5'-adenosine monophosphate (cAMPh) were studied by means of microionophoresis. It was shown that cAMPh changes the pattern of background unit activity, increasing or decreasing the discharge frequency. cAMPh changes unit responses both to acetylcholine and noradrenaline. These data permit, to assume that cAMPh participates both in adrenergic and in acetylocholinergic mechanisms of excitation processing in brain neurones.     

Regulation of uracil uptake in Escherichia coli by adenosine 3',5'-monophosphate.

Culture of a wild-type strain of Escherichia coli in the presence of cyclic AMP leads to an impairment of uracil uptake. Half maximum inhibition of uracil uptake was observed at 1.5 mM cyclic AMP. The effect seems to be specific since no inhibition was found in cultures supplemented with ATP, ADP or 5'-AMP. Similarly the inhibition was not observed in cultures of a mutant deficient in the cyclic AMP receptor protein. The inhibition in uracil uptake, found in bacteria cultured in the presence of cyclic AMP, is not a consequence of a reduction in the growth rate. On the other hand, this inhibition was observed only in cultures containing glucose or pyruvate as carbon source.     

Stimulation of gibberellin-induced germination in lettuce seeds by cyclic 3',5'-adenosine monophosphate

Cyclic 3',5'-adenosine monophosphate and sodium dibutyryl cyclic3',5'-adenosine monophosphate had no effect on dark-germinationof light-sensitive lettuce {Lacluca sativa L., var. Grand Rapids)seeds when given alone. Cyclic 3',5'-adenosine monophosphate,however, synergistically enhanced the 3 µ 10^–5 Mgibberellic acid-induced germination, but showed no such effecton kinetin-stimulated germination. 5'-AMP, in contrast to cyclic3',5'-adenosine monophosphate, had no effect on gibberellicacidinduced germination. (Received August 8, 1971; )     

Effect of cyclic 3',5'-adenosine monophosphate on the sporulation of Saccharomyces cerevisiae

Cyclic 3',5'-adenosine monophosphate and sodium dibutyryl cyclic3',5'-adenosine monophosphate had no effect on sporulation ofSaccharomyces cerevisiae, when added to a sporulation mediumnot enriched with glucose. They did, however, reverse the repressionof sporulation by glucose, when added to the sporulation mediumtogether with glucose. 5'-AMP, 5'-ADP and 5'-ATP did not reversethe repression of sporulation by glucose. (Received February 24, 1972; )