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1.
Plasmodial cells of the slime mold Physarum polycephalum become “competent” for sporulation following a prolonged period of dark starvation in the presence of nicotinamide. Sporulation can then be induced by illumination. Plasmodia are found to release into the medium during starvation one or more cellular products that promote sporulation. These products exert their effect specifically during the dark starvation period, rather than during the final phase of fruiting body construction. The sporulation control factor(s) (SCF) is nondialyzable and can stimulate the development of sporulation competence in the absence of nicotinamide. 相似文献
2.
Randall L. Kincaid Tag E. Mansour 《Biochimica et Biophysica Acta (BBA)/General Subjects》1979,588(3):342-350
The effect of several inhibitors of the enzyme cyclic 3′,5′-AMP phosphodiesterase as chemoattractants in Physarum polycephalum was examined. Of the compounds tested, 4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (Roche 20-1724/001) and 1-ethyl-4-(isopropylidinehydrazino)-1H-pyrazolo-(3,4-b)-pyridine-5-carboxylic acid ethyl ester, hydrochloride (Squibb 20009) were the most potent attractants. 3-Isobutyl-1-methyl xanthine, theophylline, and morin (a flavanoid) were moderate attractants and sometimes gave negative chemotaxis at high concentrations. Cyclic 3′,5′-AMP was an effective, but not potent attractant. A repellent effect following the positive chemotactic action was sometimes observed with cyclic 3′,5′-AMP at concentrations as high as 1 · 10−2 M. Dibutyryl cyclic AMP appeared to be a somewhat more potent attractant than cyclic 3′,5′-AMP. The 8-thiomethyl and 8-bromoderivatives of cyclic AMP, which are poorly hydrolyzed by the phosphodiesterase, were not attractants in Physarum. Possible participation of cyclic 3′,5′-AMP in the directional movement in P. polycephalum is discussed. 相似文献
3.
Cyclic adenosine 3′:5′-monophosphate (cyclic AMP) and cyclic guanosine 3′:5′-monophosphate (cyclic GMP) have been determined at half-hourly intervals throughout the mitotic cycle of Physarum polycephalum. Cyclic AMP was constant at 1pmole/mg protein throughout except for a transient peak of 17pmoles/mg protein in the last quarter of G2. Cyclic GMP was more variable (2–4pmole/mg protein) rising to 9.5pmole/mg protein during the 3 hour S period and to 7pmole/mg protein during the last hour of G2. The significance of these changes is discussed. 相似文献
4.
When Leptophaeria michotii was grown in conditions that permitted a stable periodicity of sporulation (asparagine 6.6 mM in darkness or asparagine 2.6 mM in continuous white light), the level of intracellular cyclic AMP was lower and the activity of the cyclic AMP phosphodiesterase higher in contrast to the cultures with an instable periodicity.With asparagine 6.6 mM and in darkness, theophylline (1 mM) increased the intracellular cyclic AMP level whereas caffeine (1 mM) had no effect. Theophylline (0.01 and 0.1 mM) or caffeine (0.01–1 mM) provoked a rhythm instability under these conditions. Isoproterenol (1 mM) increased the cyclic AMP level. Nevertheless, the instable rhythm observed in control fed with asparagine 2.6 mM in darkness, was partially stabilized with isoproterenol 0.01 M or 0.01–1 mM. Exogenous cyclic AMP (0.01–1 mM) provoked a complete regulation of the rhythm with asparagine 2.6 mM and a shortening of the stable period (from 27 to 21 h) when the fungus was grown on asparagine 6.6 mM.These results underlined the fact that Leptosphaeria rhythm regulation was not dependent on the cyclic AMP level only. 相似文献
5.
Preston N. Garrison Larry D. Barnes 《Biochimica et Biophysica Acta (BBA)/General Subjects》1980,633(1):114-121
Cyclic AMP, [3H]thymidine incorporation, and DNA content were measured in the cell cycle of Physarum polycephalum. A sensitive radioimmunoassay was employed to assay cyclic AMP so that plasmodia could be assayed individually. In contrast to previously published results (Lovely, J.R. and Threlfall, R.J. (1976) Biochem. Biophys. Res. Commun. 71, 789–795), no pre-mitotic peak of cyclic AMP was detected. In seven experiments levels of cyclic AMP showed only small changes in individual experiments and ranged from 1–6 pmol/mg protein in different experiments. When plasmodia in the immediate premitotic period were collected on the basis of nuclear mitotic morphology, no evidence of a peak of cyclic AMP was found. Light was found to increase plasmodial cyclic AMP in a rapid, transient fashion. However, the brief exposure of cell cycle samples to light during collection did not induce any apparent cell cycle specific peaks of cyclic AMP. Although the occurrence of extremely rapid transient peaks of cyclic AMP in the cell cycle cannot be ruled out, it appears likely that the P. polycephalum cell cycle can proceed normally without major changes in cyclic AMP. 相似文献
6.
A method is described for covalent attachment of up to 1.1 mmol of m-aminobenzeneboronic acid/g dry weight of polyacrylamide beads. Small (4 ml) columns of the derivatized beads have been used to separate quantitatively cyclic AMP from ATP in a single-step procedure. Columns of the polyacrylamide-boronate gel have been used as the basis of a convenient new assay of the soluble adenylate cyclase prepared from nuclei of Physarum polycephalum. 相似文献
7.
Randall L. Kincaid Tag E. Mansour 《Biochimica et Biophysica Acta (BBA)/General Subjects》1979,588(3):332-341
The effect of several inhibitors of the enzyme cyclic 3′,5′-AMP phosphodiesterase as chemoattractants in Physarum polycephalum was examined. Of the compounds tested, 4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (Roche 20-1724/001) and 1-ethyl-4-(isopropylidinehydrazino)-1H-pyrazolo-(3,4-b)-pyridine-5-carboxylic acid ethyl ester, hydrochloride (Squibb 20009) were the most potent attractants. 3-Isobutyl-1-methyl xanthine, theophylline, and morin (a flavanoid) were moderate attractants and sometimes gave negative chemotaxis at high concentrations. Cyclic 3′,5′-AMP was an effective, but not potent attractant. A repellent effect following the positive chemotactic action was sometimes observed with cyclic 3′,5′-AMP at concentrations as high as 1 · 10?2 M. Dibutyryl cyclic AMP appeared to be a somewhat more potent attractant than cyclic 3′,5′-AMP. The 8-thiomethyl and 8-bromoderivatives of cyclic AMP, which are poorly hydrolyzed by the phosphodiesterase, were not attractants in Physarum. Possible participation of cyclic 3′,5′-AMP in the directional movement in P. polycephalum is discussed. 相似文献
8.
Pramod K. Sinha Kedar N. Prasad 《In vitro cellular & developmental biology. Plant》1977,13(8):497-501
Summary Adenosine 3′,5′-cyclic monophosphate (cyclic AMP) phosphodiesterase activity in mouse neuroblastoma cells in culture markedly
increased during exponential growth and reached a maximal level at confluency; whereas guanosine 3′, 5′-cyclic monophosphate
(cyclic GMP) phosphodiesterase activity only slightly but significantly increased under a similar experimental condition.
The increase in cyclic AMP phosphodiesterase activity was blocked by both cycloheximide and dactinomycin, whereas the increase
in cyclic GMP phosphodiesterase was blocked by only cycloheximide. When the confluent cells were replated at low density,
the cyclic nucleotide phosphodiesterase activity decreased; however, when they were plated at high cell density which equaled
confluency, the enzyme activity did not decrease. Unlike cyclic AMP phosphodiesterase activity, cyclic GMP phosphodiesterase
activity did not change significantly in prostaglandin E1-treated cells, but decreased in cells treated with the inhibitor of phosphodiesterase. Like cyclic AMP phosphodiesterase
activity, cyclic GMP phosphodiesterase activity also did not change in cells treated with serum-free medium, X-irradiation,
sodium butyrate and 6-thioguanine.
This work was supported by USPHS NS-09230, and DRG-1273 from Damon Runyon-Walter Winchell Cancer Fund. 相似文献
9.
Jane C. Redshaw 《In vitro cellular & developmental biology. Plant》1980,16(5):377-383
Summary The effects of glucagon and dexamethasone on the activities of the enzymes involved in cyclic adenosine 3′∶5′-monophosphate
(cyclic AMP) metabolism in primary monolayer cell cultures of adult rat hepatocytes were examined. Short-term experiments
indicated that the magnitude of the cultured cells' response to glucagon, as measured by production of cyclic AMP, was essentially
the same as that for freshly isolated hepatocytes. However, the time course of this response was markedly different. Although
the activity of adenylate cyclase is maintained throughout the culture period at a level similar to that of the freshly isolated
hepatocytes, the activity of both low and highK
m forms of phosphodiesterase decreases rapidly with length of time in vitro. This is reflected by an increase in cyclic AMP
produced in response to glucagon and theophylline by cells of different ages. Dexamethasone caused an increased loss of phosphodiesterase
activity, as well as increased cyclic AMP accumulation in the presence or absence of theophylline. Various agents failed to
restore the lost phosphodiesterase activity. These results may indicate that phosphodiesterase activity is more sensitive
to the inevitable inadequacies of the in vitro environment of cultured hepatocytes than adenylate cyclase.
It was also found that a modification of the method of Seglen (1) for the preparation of isolated hepatocytes yielded cells
that had less phosphodiesterase activity than those prepared by the method of Berry and Friend (2).
This work was supported by grants from the Medical Research Council of New Zealand and the Medical Research Distribution Committe. 相似文献
10.
Pigmentation and sporulation in selected Myxomycetes 总被引:1,自引:0,他引:1
Chemical, chromatographic and spectrometric methods are used to characterize plasmodial pigments and determine relationships between pigmentation and sporulation in selected Myxomycetes. In Physarum gyrosum (white) a single pigment is identified and characterized as a flavone. Physarum polycephalum (yellow) and Didymium iridis (brown) contain four and six components, respectively, in their plasmodial pigments which test negatively for flavones but show the presence of some type of phenolic compound. No detectable component is identified in the white plasmodium of Didymium squamulosum which proved to be independent of light for fruiting. The absorption spectra of all species that were light sensitive for fruiting showed common peaks in the 300–400-mμ region, among others. Pigment changes associated with light absorption are reported for some white, yellow and brown plasmodial types. In Physarum gyrosum a yellow pigment forms in light which did not show the characteristic flavones present in the white plasmodial stage. Changes in absorption spectra are reported for Physarum polycephalum, Didymium iridis and Didymium squamulosum as the plasmodial pigments change prior to fruiting. Results show a close relationship between the physiology of plasmodial pigmentation and sporulation in the Myxomycete species studied. 相似文献
11.
A. R. Nezvetsky T. G. Orlova S. I. Beylina N. Ya. Orlov 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2012,6(1):100-104
Plasmodium of myxomycete Physarum polycephalum produces cyclic nucleotide phosphodiesterase (PDE). The extracellular PDE is cAMP-specific and highly thermostable. This
study demonstrates that the extracellular PDE of Ph. polycephalum is weakly inhibited by caffeine, isobutylmethylxantine and theophiline (type I mammalian PDE nonspecific inhibitors), dipyridamole
(mammalian PDE5, PDE6, PDE8 and PDE10 inhibitors), and erythro-9-[3-(2-hydroxynonyl)]-adenine (mammalian PDE2 inhibitor).
The enzyme does not require Mg2+ for the activity. The results show that the Ph. polycephalum extracellular PDE differs from class I PDEs, represented by mammalian PDE1-PDE11, and, most likely, belongs to a poorly investigated
class II PDEs. 相似文献
12.
Kohji Hasunuma 《Journal of plant research》1985,98(3):203-217
A wild type strain ofNeurospora crassa produced aerial hyphae and luxuriant conidia in standing culture in low phosphate liquid media.nuc-1 andnuc-2, which have no ability to derepress repressible cyclic phosphodiesterase (cPDase) (3′; 5′-cyclic AMP 5′-nucleotidohydrolase,
EC 3.1.4.17) and several other repressible enzymes, did not form them. Heterocaryon between them restored the abilities not
only to produce aerial hyphae and conidia but also to produce cPDase. Revertants fromnuc-1 and a mutant in alkaline phosphatase,pho-2, produced aerial hyphae and conidia in low phosphate condition, whereas a mutant in cPDase,pho-3, produced only a limited amount of them.
In media containing low levels of 2′, 3′-cAMP, the wild type, the revertants fromnuc-1, pho-2 andpho-3 produced aerial hyphae and conidia in abundance, whereas in media containing 3′, 5′-cAMP these strains produced no or only
limited amounts of them. In low phosphate medianuc-1, nuc-2 andpho-3 showed higher levels of 3′, 5′-cAMP as compared with those strains which have the ability to derepress cPDase. The cPDase
activities in crude mycelial extracts fromnuc-1 andpho-3 grown in low phosphate media were 5.6 and 17.5% of that ofpho-2 when assayed for 3′,5′-cAMP at an intracellular level of 2 μM. 相似文献
13.
Summary Addition of N6,O2′-Dibutyryladenosine cyclic 3′,5′ monophosphate (DB cyclic AMP) plus theophylline or transfer to medium containing 0.2% serum
slowed the growth of cultured mouse mastocytoma cells and eventually arrested their growth in G1 phase. Examination of the
properties of cells arrested by either procedure suggested that the drugs arrested cells in G1 phase 1.5–2 h after the point
of low serum arrest. Cycloheximide prevented the recovery of cell growth after low serum or drug-induced arrest demonstrating
that protein synthesis was necessary to pass either growth restriction point. Cordycepin also prevented drug-arrested cells
from progressing into cycle indicating a requirement for RNA synthesis to overcome the drug-induced growth arrest. Evidence
is also presented that DB cyclic AMP prevented the cells receiving a pulse of calcium necessary to proceed past the DB cyclic
AMP-sensitive growth restriction point. It is suggested that high cyclic AMP levels prevent mastocytoma cells from receiving
a surge of calcium in G1 phase that is necessary if the cells are to proceed to S phase and eventually divide. 相似文献
14.
N. B. Matveeva M. A. Morozov A. R. Nezvetsky T. G. Orlova V. A. Teplov S. I. Beylina 《Biophysics》2010,55(6):982-986
Possible involvement of extracellular cAMP-specific phosphodiesterase in the control of cell motile behavior has been investigated
in Physarum polycephalum plasmodium, a multinuclear amoeboid cell with the autooscillatory mode of motility. It was found that the rate of the hydrolysis
of 10 mM cAMP by a partially purified preparation of cAMP-specific phosphodiesterase secreted by the plasmodium in the course
of migration decreases 20–30 times under the action of 1 mM dithiothreitol. In the presence of 1–5 mM of this strong reducing
agent, the onset of the plasmodium spreading and the transition to the stage of migration were delayed in a concentration-dependent
manner. In accordance with the morphological pattern of motile behavior, the duration of the maintenance of high frequency
autooscillations, which normally precede the increase in the rate of the spreading and appear also in response to the application
of attractants at spatially uniform concentrations, strongly increased by the action of dithiothreitol. The results obtained
suggest that the autocrine production of cAMP and extracellular cAMP-specific phosphodiesterase is an important constituent
of the mechanism controlling the motile behavior of the Physarum polycephalum plasmodium. 相似文献
15.
Costanzo G Pino S Botta G Saladino R Di Mauro E 《Origins of life and evolution of the biosphere》2011,41(6):559-562
Nucleic bases are obtained by heating formamide in the presence of various catalysts. Formamide chemistry also allows the
formation of acyclonucleosides and the phosphorylation of nucleosides in every possible position, also affording 2′,3′ and
3′,5′ cyclic forms. We have reported that 3′,5′ cyclic GMP and 3′,5′ cyclic AMP polymerize in abiotic conditions yielding
short oligonucleotides. The characterization of this reaction is being pursued, several of its parameters have been determined
and experimental caveats are reported. The yield of non-enzymatic polymerization of cyclic purine nucleotides is very low.
Polymerization is strongly enhanced by the presence of base-complementary RNA sequences. 相似文献
16.
N. B. Matveeva V. A. Teplov S. I. Beylina 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2010,4(1):70-76
In order to elucidate the function of inositol 1,4,5-trisphosphate (IP3)-activated reticular Ca2+ channel (IP3R) in autooscillatory contractile activity of Physarum polycephalum plasmodium, we applied 2-aminoethoxydiphenyl borate (2-APB), a membrane-permeable inhibitor of IP3-induced Ca2+ release. Taking into account that for the type 1 IP3 R the inhibitory efficacy of 2-APB decreases with the rise of the IP3 level [Bilmen, J.G. and Michelangeli, F., Cell Signal., 2002, vol. 14, no. 11, pp. 955–960], 2-APB was applied to plasmodium in normal conditions and after the treatment with glucose
or 3-O-methylglucose, the attractants capable to induce an elevation of the IP3 production. We found that 20–50 μM 2-APB induced a reversible cessation of contractile autooscillations, which occurred in
two different modes: as a fast stop and a gradual damping. The damping of oscillations was accompanied by an increase in their
period, a prolongation of the contraction phase, and, often, by an increase in the mean level of the contraction force. The
number of species responding by the fast stop at a 2-APB concentration of 50 μM was two times greater than at 20 μM 2-APB.
In the presence of the attractants in concentrations of 10 and 50 mM, the fast stop was never observed at 20 μM of 2-APB.
Moreover, the damping of oscillations was preceded by a period of varying duration, when the regular oscillatory mode was
maintained. We conclude that the fast stop results from the direct inter-action of 2-APB with IP3R of Physarum polycephalum plasmodium and that IP3R is indispensable for the plasmodial oscillator. 相似文献
17.
Enteropathogenic Escherichia coli (EPEC) triggers a large release of adenosine triphosphate (ATP) from host intestinal cells and the extracellular ATP is broken
down to adenosine diphosphate (ADP), AMP, and adenosine. Adenosine is a potent secretagogue in the small and large intestine.
We suspected that ecto-5′-nucleotidase (CD73, an intestinal enzyme) was a critical enzyme involved in the conversion of AMP
to adenosine and in the pathogenesis of EPEC diarrhea. We developed a nonradioactive method for measuring ecto-5′-nucleotidase
in cultured T84 cell monolayers based on the detection of phosphate release from 5′-AMP. EPEC infection triggered a release
of ecto-5′-nucleotidase from the cell surface into the supernatant medium. EPEC-induced 5′-nucleotidase release was not correlated
with host cell death but instead with activation of phosphatidylinositol-specific phospholipase C (PI-PLC). Ecto-5′-nucleotidase
was susceptible to inhibition by zinc acetate and by α,β-methylene-adenosine diphosphate (α,β-methylene-ADP). In the Ussing
chamber, these inhibitors could reverse the chloride secretory responses triggered by 5′-AMP. In addition, α,β-methylene-ADP
and zinc blocked the ability of 5′-AMP to stimulate EPEC growth under nutrient-limited conditions in vitro. Ecto-5′-nucleotidase
appears to be the major enzyme responsible for generation of adenosine from adenine nucleotides in the T84 cell line, and
inhibitors of ecto-5′-nucleotidase, such as α,β-methylene-ADP and zinc, might be useful for treatment of the watery diarrhea
produced by EPEC infection. 相似文献
18.
Robert O. Hussa Michaei T. Story Roland A. Pattillo Robert G. Kemp 《In vitro cellular & developmental biology. Plant》1977,13(7):443-449
Summary The secretion of human chorionic gonadotropin (hCG) is stimulated by addition of N6, O2′-dibutyryl cyclic 3′:5′-AMP (dbcAMP) or theophylline to normal term placenta and human malignant trophoblast cells in vitro.
To understand better the specificity of this process. malignant trophoblast cultures were incubated with 3′:5′-cyclic AMP
(cAMP) derivatives, prostaglandins and other agents for 1 to 3 days, and the secretion of radioimmuno-assayable hCG was measured.
Whereas dbcAMP was the most potent agent in stimulating secretio of hCG, the N6- and O2′-monobutyryl derivatives of cAMP and phosphodiesterase inhibitors (theophylline, papaverine, 3-isobutyl-1-methylxanthine)
also increased the secretion of the hormone. A slight increase in hCG secretion was observed following addition of adenine.
By contrast, butyrate, cAMP, cyclic 3′:5′-GMP (cGMP), dbcBMP, 5′-AMP, adenosine, L-epinephrine and prostaglandins E1, E2, F1α and F2α were ineffective. Particulate fractions from sonicates of malignant trophoblast cultures contained adenylate cyclase activity
which was stimulated more than 10-fold by NaF, but not by either catecholamines or prostaglandins. The relatively specific
stimulation of hCG secretion suggested that a regulatory process involving cAMP may have physiological significance in the
trophoblast.
This investigation was supported by Grant Nos. CA14232 and CA16539 awarded by the National Cancer Institute, DHEW. 相似文献
19.
Here, the extracellular interconversion of nucleotides and nucleosides was investigated in rat hippocampal slices and synaptosomes
by an HPLC-UV technique. Adenosine 5′-triphosphate (ATP) was converted to adenosine 5′-diphosphate (ADP), adenosine 5′-monophosphate
(AMP), adenosine, inosine, and hypoxanthine in the slices, whereas ADP elicited parallel and concentration-dependent formation
of ATP and AMP. The specific adenylate kinase inhibitor diadenosine pentaphosphate decreased the rate of decomposition of
ADP and inhibited the formation of ATP. No substantial changes in the interconversion of ADP to ATP and AMP were found in
the presence of dipyridamole, flufenamic acid, the P2 receptor antagonist pyridoxal-5-phosphate-6-azophenyl-2′,4′-disulphonic
acid tetrasodium (PPADS), and the alkaline phosphatase substrate para-nitrophenylphosphate. Negligible levels of nucleotides were generated when uridine 5′-diphosphate (UDP), AMP or adenosine
were used as substrates. Ecto-adenylate kinase activity was also observed in purified synaptosomes. In summary, we demonstrate
the presence of an ecto-adenylate kinase activity in the hippocampus, which is a previously unrecognized pathway that influences
the availability of purines in the central nervous system. 相似文献
20.
Ginette Courtois Gilles Paradis Anne Barden Gérald Lemieux 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1982,696(1):87-93
The phosphate content of ribosomal proteins S3, L1 and L24 has been determined in the course of spherulation of Physarum polycephalum. The major phosphoprotein, S3, was completely dephosphorylated after 4 h of differentiation. The phosphate content of L1 and L24 was not altered during the differentiation. The cellular level of ATP remained constant for at least 5 h. A 3-fold reduction of cyclic AMP concentration occurred in the first hour, followed by a slow increase to a final value of twice the level observed in growing cells. The results showed that the phosphorylation of ribosomal proteins is regulated by at least two different mechanisms and that the dephosphorylation of S3 is not induced by a lack of cellular ATP. Although cyclic AMP might trigger the dephosphorylation of S3, the phosphate content of this protein remained at a very low value even when the cellular concentration of cyclic AMP rose significantly. Since the polysome level remains constant during the first 24 h of spherulation, the phosphorylation of S3 is not necessary for active protein synthesis and the phosphorylation of L1 and L24 is not involved in ribosome inactivation, which occurs after 24 h. 相似文献