Effect of ethionine on the synthesis of β-galactosidase inEscherichia coli

Ethionine at concentrations of 10⁻³M, 5×10⁻³M and 10⁻²M inhibits growth, both of β-galactosidase inducible ML-30 and constitutive ML-308Escherichia coli strains. The protein synthesis (measured by the incorporation of l-leucine-¹⁴C and l-aspartic-¹⁴C acid into proteins) of these strains is inhibited to the same extent as their growth. The synthesis of inducible and constitutive β-galactosidase produced by the strains ML-30 and ML-308, respectively, is considerably inhibited by ethionine.     

Role of cyclic adenosine-3′,5′-monophosphate in olfactory reception

The action of cyclic adenosine-3,5-monophosphate (3,5-AMP) and of substances modifying the rate of its breakdown (inhibitors and activators of phosphodiesterase) on the olfactory epithelium was investigated in frogs. The slow electrical response of the olfactory epithelium to stimulation by solutions of various substances was recorded. Cyclic 3,5-AMP and its dibutyryl derivative were found to excite the olfactory receptors effectively. Responses to these substances developed after an appreciably longer delay than responses to stimulation by solutions of odiferous substances. It is postulated that the depolarizing action of 3,5-AMP and dibutyryl 3,5-AMP is manifested only after they have penetrated inside the receptor cell through its membrane. Both 5-AMP and cyclic 2,3-AMP were ineffective. In the next series of experiments the integral receptor potential was recorded in response to short stimulation by the vapor of an odiferous substance. The duration of this potential was increased after treatment of the olfactory epithelium with phosphodiesterase inhibitors: methylxanthines or papaverine. Conversely, the negative wave of the integral receptor potential was shortened under the influence of the phosphodiesterase activator imidazole. Cyclic 3,5-AMP is considered to play the role of mediator in the mechanism of excitation of the olfactory receptor; during interaction between an odiferous substance and the receptor, adenyl cyclase is activated and the concentration of 3,5-AMP increases; this, in turn, causes depolarization of the receptor cell membrane.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 5, No. 4, pp. 415–422, July–August, 1973.     

Induction of blastocladiella emersonii germination by cyclic adenosine-3′, 5′-monophosphate

The role of adenosine 3′,5′-monophosphate (cyclic AMP) in the control of Blastocladiella emersonii germination was studied. This differentiative transition may be induced by replacing K⁺, a classical inducer, by cyclic AMP or by competitive inhibitors of cyclic AMP phosphodiesterase activity. When zoospores are treated simultaneously with two inducers at non-effective concentrations, a synergistic effect is observed between cyclic AMP and either KCl or adenine. The calcium ionophore A23187 per se is not able to elicit germination, but the association of A23187 and sub-optimal concentrations of cyclic AMP is effective. These results suggest that germination may depend on a correlation between the intracellular mobilization of calcium and cyclic AMP levels.     

Control of derepressed β-galactosidase synthesis inEscherichia coli

1. The synthesis of β-galactosidase in a constitutive mutant ofEscherichia coli (ML 308, i^-z⁺y⁺a⁺) responds to the nutritional environment. Repression can be reversed by cyclic AMP.
2. The greatest degree (%) of repression by metabolisable compounds is obtained when cells utilising glycerol (0%) are given, in addition, pyruvate (67%), serine (57%) which can be converted to pyruvate, or substrates of phosphotransferase systems (20–40%) which liberate pyruvate in their operation. Furthermore, pyruvate represses β-galactosidase synthesis in a phosphoenolpyruvate synthaseless mutant. Pyruvate, however, does not repress in a pyruvate dehydrogenaseless mutant and it follows that pyruvate itself is not the agent of repression.
3. Raffinose, a non-metabolisable galactoside, represses synthesis of β-galactosidase during growth on glycerol. Over a wide range, repression depends on raffinose concentration as does a lowered pool of ATP, rate of oxygen consumption and growth rate. All these parameters are inter-related but, in particular, β-galactosidase synthesis depends on the size of the ATP-pool presumably because this also limits synthesis of cyclic AMP under these conditions.

     

The synthesis of β-galactosidase inEscherichia coli in the presence of 7-azatryptophan

The presence of 7-azatryptophan an analogue of tryptophan in the growth medium ofEscherichia coli resulted in a considerable inhibition of the synthesis of active β-galactosidase. No synthesis of an immunologically cross-reacting protein was detected. In addition, the replacement of tryptophan by the analogue rendered the enzyme more susceptible to heat, urea and trypsin as compared with the normal enzyme. The inhibition of growth and enzyme synthesis by 7-azatryptophan was reversed by tryptophan. The analogue did not exhibit any effect on the synthesis and activity of β-galactoside permease.     

Simultaneous and successive induction of synthesis of β-Galactosidase and tryptophanase inEscherichia coli K 12 in the chemostat

β-Galactosidase and tryptophanase were induced either simultaneously or successively during continuous cultivation of the inducible strainEscherichia coli K 12 in the chemostat. Growth was limited by glycerol and the dilution rate was 0.1 h⁻¹. During both the simultaneous and successive induction specific rates of synthesis, as well as maximum enzyme levels, were identical with those obtained after independent induction of individual enzymes. As compared with batch cultivation, β-galactosidase reached the same specific rate of synthesis in the chemostat, whereas the specific rate of synthesis of tryptophanase in the chemostat was up to five times higher.     

Involvement of cyclic adenosine-3′, 5′-monophosphate in chloronema differentiation in protonema cultures of Funaria hygrometrica

The role of purine and pyrimidine ribosides, nucleotides and substituted xanthines in the differentiation of chloronema filaments in suspension cultures of protonema of the moss Funaria hygrometrica Hedw. has been examined. Cyclic adenosine-3,5-monophosphate (cAMP) and mono-and dibutyryl cAMP evoked the maximum response in wild-type protonema. ADP and ATP also enhanced chloronema differentiation but were less active than cAMP; pyrimidine derivatives were completely inactive. Inhibitors of cyclic-nucleotide phosphodiesterase aminophylline, theophylline and ICI 58, 301 (3-acetamido-6-methyl-8-n-propyl-s-triazolo-(4,3a)-pyrazine)-mimicked the effect of cAMP. A leaky, chloronema-repressed mutant was isolated and in this mutant cAMP was much more active than cyclic guanosine monophosphate and ADP in enhancing chloronema differentiation. These results strongly indicate that cAMP is involved in chloronema differentiation in Funaria, and a hypothesis on growth regulation in protonema cell cultures is proposed.Abbreviations cAMP, cyclic AMP cyclic adenosine-3, 5-monophosphate - cCMP, cGMP, cIMP cyclic cytosine-, guanosine-and inosine-3, 5-monophosphates, respectively - IAA indole-3-acetic acid - ICI 58,301 3-acetamido-6-methyl-8-n-propyl-s-triazolo-(4,3a)-pyrazine     

Effect of adenosine 3′,5′-(cyclic)-monophosphate on the synthesis of progestational steroids by rabbit ovarian tissue in vitro

1. Adenosine 3',5'-(cyclic)-monophosphate (3',5'-AMP) stimulates the synthesis of progestational steroids by rabbit ovarian tissue in vitro. 2. Other adenosine phosphates fail to increase steroidogenesis. 3. The ratio of 20alpha-hydroxypregn-4-en-3-one to progesterone, the maximal response of the tissue, and the responses of separated corpora lutea and interstitial tissue produced by luteinizing hormone are closely paralleled by 3',5'-AMP. 4. In tissues maximally stimulated by luteinizing hormone, 3',5'-AMP fails to produce an additional response. 5. The addition of theophylline, an inhibitor of phosphodiesterase, potentiates the effects of 3',5'-AMP and also luteinizing hormone. 6. The results obtained suggest that 3',5'-AMP is a mediator of the action of luteinizing hormone on progestational steroid synthesis by rabbit ovarian tissue.     

Simultaneous and gradual induction of β-galactosidase and tryptophanase synthesis in anEscherichia coli batch culture

β-Galactosidase and tryptophanase can be induced inEscherichia coli simultaneously or gradually during a batch cultivation. In the strainEscherichia coli K 12 and ML 30, in which the synthesis of the two enzymes was induced simultaneously, only the synthesis of tryptophanase partially decreased, whereas the synthesis of β-galactosidase was not influenced. In the strains B 28 and ATCC 9637 the synthesis of both enzymes was partially decreased. On a gradual induction of these enzymes in the strainEscherichia coli E 12 only the synthesis of tryptophanase decreased. Thus, the results obtained here resemble those observed during the simultaneous induction. In addition, it was found that it is not important which of the two enzymes is induced as the first one.     

Effect of dibutyryl cyclic adenosine 3′5′-monophosphate on mitotic activity in the thyroid of hypophysectomized rats

Summary Effect of dibutyryl cyclic adenosine 35-monophosphate (dbcAMP) on mitotic activity in the thyroid of hypophysectomized rats has been examined. It has been demonstrated that dbcAMP stimulates the incidence of mitoses in the thyroid follicular cells. It is therefore suggested that cAMP may be a mediator of the proliferogenic effect of TSH on the thyroid in vivo. Cyclic AMP could also release some unidentified growth-promoting factors for the thyroid. A direct stimulating effect of dbcAMP on the proliferation of the thyroid follicular cells is assumed to be possible as well.     

The effect of glucose and manganese on adenosine-3′, 5′-monophosphate levels during growth and differentiation of Aspergillus nidulans

The role of cyclic adenosine monophosphate (cAMP) during growth and development of Aspergillus nidulans was investigated. In normal cultures the highest amount of cAMP, expressed on a dry weight basis, was found after 24 h of growth when still more than 5% glucose was present in the medium. After depletion of the medium even a slight fall in cAMP was noted. Glucose concentrations ranging from 0.5–12% resulted in a slight decrease in the amount of cAMP as measured after 24 h of growth.Cultures with manganese deficiency resulted in a low cAMP level after 24 h of growth. However, the exhaustion of glucose in the absence of manganese was connected with a sharp increase in cAMP. This indicates that manganese shortage was not a direct cause of the low cAMP level after 24 h. The amount of cAMP rose with increasing concentration of manganese in the medium until a maximum at 0.25 M. It is tempting to speculate that this rise in cAMP in the manganese deficient culture is explained by the absence of glucose, that in the control culture is derived from the breakdown of the reserve material -1,3-glucan.Addition of manganese after glucose exhaustion to a manganese deficient culture induced cleistothecium formation. However, they contained only a few ascospores indicating the importance of -1,3 glucan as a carbon and energy source for ascospore formation. The regulation of the level of cAMP by the transport of glucose into the cell or its intracellular concentration is discussed.     

Further observations on the effect of ethionine on the synthesis of β-galactosidase inEscherichia coli: Formation of an immunologically cross-reacting protein

It was found that ethionine partially inhibits the transport of the inducer (TMG) of β-galactosidase into the cells ofEscherichia coli ML-30. The synthesis of β-galactosidase-specific messenger RNA is not inhibited. Ethionine appears to be incorporated into proteins synthesized by the strains used. The incorporation of ethionine into the molecule of β-galactosidase results in the synthesis of an enzymically inactive, immunologically cross-reacting protein.     

Influence of theophylline on concentrations of cyclic 3′,5′-adenosine monophosphate and cyclic 3′,5′-guanosine monophosphate of rat brain

The influence of theophylline (2.5–100 mg/kg p.o.) on cyclic 3,5-adenosine monophosphate (cAMP) and cyclic 3,5-guanosine monophosphate (cGMP) in brain of Sprague-Dawley rats (0.5–3.0 hr after administration of theophylline) was investigated. It was found that theophylline increases cAMP and cGMP levels when administered in a dose of 25 mg/kg or higher. A significant decrease of cGMP level was observed after administration of 10 mg/kg. The results of this study suggest that the influence of theophylline on cyclic nucleotide levels of rat brain is the result of two factors: (a) inhibitory properties of theophylline on cAMP and cGMP phosphodiesterases and (b) competition of theophylline with adenosine.     

Inhibition of β-galactosidase synthesis inEscherichia coli after infection with different DNA and RNA phages

Infection ofEscherichia coli with T1, T2r⁺, T3 and T4 phages leads to an immediate inhibition of β-galactosidase synthesis. Similar results were obtained with the virulent mutant of phage lambda. The degree of inhibition of β-galactosidase synthesis depends on the time delay between the addition of the inducer and the phage particles, and on the amount of phage DNA, which has penetrated into the host cell. RNA phage MS2 exhibited no inhibitory effect on enzyme synthesis.     

Synthesis of β-galactosidase inEscherichia coli in the presence of phenylalanine analogues

The effect of phenylalanine analogues (p-F-phenylalanine, phenylserine and furylalanine) is described on the synthesis of inducible β-galactosidase inEscherichia coli ML-30 and phenylalanine requiring mutant ML-48. The incorporation of these analogues into the enzyme molecule results in the formation of a protein sensitive to a different extent to heat, urea and trypsin. The influence of the analogues on the ability to concentrate inducer inside the cells is also described. The different effect of the analogues on the synthesis and stability of the enzyme is discussed.     

Effect of guanosine 3′:5′-monophosphate on the hydroosmotic activity of adenosine 3′:5′-monophosphate in toad urinary bladder

Guanosine 3′:5′-monophosphate has a slight hydroosmotic effect on toad urinary bladder. Furthermore, this nucleotide strongly inhibits the responses to 3′:5′-adenosine monophosphate and oxytocin. The response to an increase in medium tonicity is not modified by the guanosine nucleotide. A role for guanosine 3′:5′-monophosphate in the regulation of water permeability in toad urinary bladder is proposed.     

Calcium,cyclic adenosine 3′, 5′-monophosphate,and the control of cell proliferation: A review

Conclusion By manipulating the rat's calcium balance, we have discovered that the calcium homeostatic system is a main regulator of cell proliferation in the bone marrow and thymus gland. Although the limits of the system's sphere of influence have yet to be completely defined, it is already known to include such diverse elements as chicken fibroblasts, liver parenchymal cells, and circulating small lymphocytes. Of even greater significance is the possibility that the ubiquitous cyclic AMP is calcium's partner and may even be the ion's intracellular agent for the control of cell proliferation. Thus, we now have a wide variety of possible explanations for diseases involving uncontrolled cell proliferation. Issued as NRCC No. 12996. Supported by a grant from the American Cancer Society.     

The effect of anaerobiosis on the induced synthesis of β-galactosidase in non-growingEscherichia coli

Depending on conditions of aeration maltose and glucose were found to exhibit different effects on the inducible synthesis of β-galactosidase in aerobically grown cells ofEscherichia coli starving for an exogenous source of nitrogen; both saccharides repressed the synthesis of the enzyme under aerobic conditions, while the above-mentioned saccharides were essential for the enzyme synthesis under anaerobic conditions. The presence of maltose in the medium resulted in the repression of the enzyme synthesis in anaerobically grown cells starving for an exogenous nitrogen source under anaerobic conditions. The synthesis of β-galactosidase-specific messenger RNA was completely blocked and the synthesis of the enzyme proper considerably inhibited in aerobically grown cells incubated anaerobically in a medium without nitrogen and carbon sources.