Circadian rhythmicity in the activities of adenylate cyclase and phosphodiesterase in synchronously dividing and stationary-phase cultures of the achlorophyllous ZC mutant of Euglena gracilis

1991 ◽  
Vol 100 (2) ◽  
pp. 365-369 ◽  
Author(s):  
J. Tong ◽  
I.A. Carre ◽  
L.N. Edmunds
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Euglena Gracilis ◽  
Circadian Variation ◽  
Constant Darkness ◽  
Key Factors ◽  
Peak Phase ◽  
Methyl Xanthine ◽  
Daily Oscillation

Key factors in the adenosine 3′,5′-cyclic monophosphate (cyclic AMP) metabolic pathway are two enzymes responsible for its generation and degradation, namely, adenylate cyclase (AC) and phosphodiesterase (PDE). In LD: 12,12 (12 h light, 12 h dark), these enzymes were found to undergo bimodal, circadian variation of activity in both dividing and nondividing cultures of the photosynthesis-deficient, achlorophyllous ZC mutant of Euglena gracilis Klebs (Z). Maximal AC activity occurred 2 h after the onset of the light interval (CT 02) and at the beginning of darkness (CT 12–14); these times corresponded to the acrophase profile for the rhythmic changes in cyclic AMP content that have been previously reported. The activity of PDE also exhibited a daily oscillation, but with an inverse phase pattern. Both the AC and PDE activity rhythms persisted after the cultures were transferred from LD: 12,12 to constant darkness. The activity of AC was activated significantly in vivo by forskolin at the trough phase (CT 20), while that of PDE was inhibited by 3-isobutyl-1-methyl-xanthine (IBMX) at its peak phase. These results indicate that the rhythms of both AC and PDE may be the main factors generating the circadian oscillations of cyclic AMP content in Euglena, which appear to be under control of an endogenous pacemaker.

scholarly journals Arginine-Vasopressin Expressing Neurons in the Murine Suprachiasmatic Nucleus Exhibit a Circadian Rhythm in Network Coherence in vivo

2021 ◽  
Author(s):  
Adam Stowie ◽  
Zhimei Qiao ◽  
Daniella Do Carmo Buonfiglio ◽  
J. Christopher Ehlen ◽  
Morris Benveniste ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Suprachiasmatic Nucleus ◽  
Arginine Vasopressin ◽  
Single Cells ◽  
Circadian Variation ◽  
Population Level ◽  
Correlational Analysis ◽  
Constant Darkness ◽  
Peak Time

AbstractThe Suprachiasmatic Nucleus (SCN) is composed of functionally distinct sub-populations of GABAergic neurons such as vasoactive intestinal polypeptide (VIP)-, arginine vasopressin (AVP)-, gastrin releasing peptide (GRP)-, and neuromedin S (NMS)-expressing neurons which form a neural network responsible for synchronizing most physiological and behavioral circadian rhythms in mammals. To date, little is known regarding which aspects of SCN rhythmicity are generated by individual SCN neurons or neuronal sub-populations and which aspects result from neuronal interaction within a network. In this study, we address this question utilizing in vivo miniaturized microscopy to measure fluorescent GCaMP-mediated calcium dynamics in AVP neurons in the intact SCN of awake, behaving mice. This approach permits analysis of rhythms of single cells, populations, and correlational analysis among groups of AVP neurons in a field of view across the circadian and diurnal day and night. We report that AVP neurons in the murine SCN exhibit a periodic oscillatory increase in calcium of approximately 14 seconds across the day and night, in both constant darkness and under a 12:12 light-dark (LD) cycle. Using in vivo optogentically-targeted single unit activity recording, we demonstrated that these slow calcium waves are likely the result of burst-firing characteristic of AVP neurons previously reported for other brain regions. Rhythmicity analysis of several fluorescence measures suggests that individual AVP neurons exhibit unstable and stochastic rhythms, with approximately 30% of the neurons rhythmic during any given day across lighting conditions, and weak or absent rhythmicity at the population level. Network-level cross-correlational analysis revealed that coherence among neuron pairs also exhibited stochastic rhythms with about 25% of pairs rhythmic at any time. Notably, this analysis revealed a stronger rhythm at the population level than was observed in single cell analysis. The peak time of maximal coherence among AVP neuronal pairs occurs between CT/ZT 6 and 9, coinciding with the timing of maximal neuronal activity with the SCN as a whole. These results are the first to demonstrate robust circadian variation in the coordination between apparently weakly rhythmic or arrhythmic neurons suggesting that, for AVP neurons, interactions between neurons in the SCN are more influential than individual or single subpopulation activity in the regulation of mammalian circadian rhythms.

Cannabinoid effects on adenylate cyclase and phosphodiesterase activities of mouse brain

1977 ◽  
Vol 55 (4) ◽  
pp. 934-942 ◽  
Author(s):  
Thomas W. Dolby ◽  
Lewis J. Kleinsmith
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Mouse Brain ◽  
Biogenic Amine ◽  
Specific Activity ◽  
Intraperitoneal Administration ◽  
The Brain

The experiments presented in this paper examine the mechanisms underlying the ability of cannabinoids to alter the in vivo levels of cyclic adenosine 3′,5′-monophosphate (cyclic AMP) in mouse brain. It was found that changes in cyclic AMP levels are a composite result of direct actions of cannabinoids on adenylate cyclase (EC 4.6.1.1) activity and indirect actions involving the potentiation or inhibition of biogenic amine induced activity of adenylate cyclase. Furthermore, the long-term intraperitoneal administration of 1-(−)-Δ-tetrahydrocannabinol to mice produced a form of phosphodiesterase (EC 3.1.4.17) in the brain whose activity is not stimulated by Ca2+, although its basal specific activity is similar to that of control animals. In vitro, the presence of the cannabinoids caused no significant changes in activity of brain PDE at the concentrations tested. Some correlations are presented which imply that many of the observed behavioral and physiological actions of the cannabinoids in mammalian organisms may be mediated via cyclic AMP mechanisms.

Renal cyclic AMP accumulation and adenulate cyclase stimulation by erythropoietic agents

1975 ◽  
Vol 229 (5) ◽  
pp. 1387-1392 ◽  
Author(s):  
GM Rodgers ◽  
JW Fisher ◽  
WJ George
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Regional Distribution ◽  
Renal Medulla ◽  
Iron Incorporation ◽  
Erythropoietin Production ◽  
Cyclic Amp Accumulation ◽  
Stimulation Of

The regional distribution of cyclic AMP in the kidney was determined following erythropoietic stimulation with hypoxia and cobalt. Following these stimuli, increases in renal cyclic AMP concentrations were restricted to the cortex. The basis for this localization in the case of cobalt treatment was found to reside in the stimulation of renal cortical adenylate cyclase activity in vitro by concentrations of cobalt similar to those found in vivo. The level of cobalt in the cortex after cobalt treatment was found to approach 500 mumol/kg of tissue, whereas no detectable levels of cobalt were found in the renal medulla. Additionally, other agents such as parathyroid hormone and lactic acid, that are known to lack stimulatory effects on medullary adenylate cyclase, were found to stimulate the cortical enzyme. This stimulation of renal cortical adenylate cyclase correlates with enhanced erythropoiesis as demonstrated by increased radiolabeled iron incorporation into erythrocytes. These results support previous reports which suggest that renal cortical cyclic AMP mediates erythropoietin production in response to erythropoietically active agents.

EFFECT OF HUMAN CHORIONIC GONADOTROPHIN ON ADENYLATE CYCLASE ACTIVITY AND TESTOSTERONE CONTENT IN RAT TESTICULAR MITOCHONDRIA

1977 ◽  
Vol 75 (1) ◽  
pp. 119-126 ◽  
Author(s):  
SOREL SULIMOVICI ◽  
M. S. ROGINSKY
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Dibutyryl Cyclic Amp ◽  
Trophic Hormone

The adenylate cyclase activity and the concentration of testosterone in testicular mitochondria from immature rats were measured after administration of human chorionic gonadotrophin (HCG) or dibutyryl cyclic AMP in vivo or in vitro. Intratesticular injection of HCG produced an increase in adenylate cyclase activity which preceded the rise in the level of testosterone, whereas addition of the trophic hormone in vitro resulted in simultaneous increases. Administration of dibutyryl cyclic AMP in vivo enhanced the testosterone content of the mitochondria. However, the cyclic nucleotide added in vitro at concentrations up to 5 mmol/l had no effect. Cycloheximide injected intraperitoneally before the administration of HCG abolished the stimulatory effect of the trophic hormone on the level of testosterone in the mitochondria, whereas chloramphenicol had no effect. These results, although they confirm the role of cyclic AMP as an intermediate in the stimulatory effect of HCG on the concentration of testosterone in rat testis, do not support a role for mitochondrial adenylate cyclase in this action. A protein regulator(s) formed extramitochondrially appears to be involved in the stimulatory effect of gonadotrophins on steroidogenesis.

Effects of Glucocorticoid Deficiency on Renal Medullary Cyclic Adenosine Monophosphate of Rats

1978 ◽  
Vol 54 (5) ◽  
pp. 573-577 ◽  
Author(s):  
K. Kurokawa ◽  
E. Aznar ◽  
C. Descoeudres ◽  
Anicia Zulueta ◽  
S. G. Massry
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Antidiuretic Hormone ◽  
Adenosine Monophosphate ◽  
Water Diuresis ◽  
Glucocorticoid Deficiency ◽  
Impaired Water ◽  
Adrenalectomized Rats

1. The effects of adrenalectomy on the adenylate cyclase—adenosine 3′:5′-cyclic monophosphate (cyclic AMP) system of rat renal medulla were examined to evaluate the mechanism of the impaired water diuresis in glucocorticoid deficiency. 2. Concentrations of cyclic AMP in medullary tubules from adrenalectomized rats were significantly higher than in the tubules from control animals both in the presence and absence of antidiuretic hormone. 3. This abnormality was corrected by the treatment in vivo of the adrenalectomized rats with dexamethasone, but addition of this drug to the incubation medium did not abolish the differences in cyclic AMP between tubules from adrenalectomized and normal rats. 4. The activity of adenylate cyclase or cyclic AMP phosphodiesterase in vitro was not affected by adrenalectomy. 5. In glucocorticoid deficiency, the concentration of cyclic AMP in medullary tubules is increased both with and without antidiuretic hormone. This abnormality may render medullary tubules more permeable to water and may underlie the impaired water diuresis in glucocorticoid deficiency.

Circadian changes in cyclic AMP levels in synchronously dividing and stationary-phase cultures of the achlorophyllous ZC mutant of Euglena gracilis

1989 ◽  
Vol 94 (2) ◽  
pp. 267-272
Author(s):  
ISABELLE A. CARRÉ ◽  
DANIELLE L. LAVAL-MARTIN ◽  
LELAND N. EDMUNDS
Keyword(s):  
Cell Division ◽  
Cyclic Amp ◽  
Euglena Gracilis ◽  
Phase Response Curve ◽  
Circadian Variation ◽  
Light Signal ◽  
Circadian Oscillator ◽  
Circadian Oscillation ◽  
Continuous Darkness ◽  
Free Running

Oscillations in adenosine 3′,5′-cyclic monophosphate (cyclic AMP) level have been proposed to be part of the biochemical feed-back loop(s), or ‘clock(8)’, believed to underlie circadian rhythmicity. This possibility has been examined for a cellular circadian oscillator in synchronously dividing (or nondividing) cultures of the photosynthesis- deficient ZC mutant of the alga Euglena gracilis Klebs (Z). We have demonstrated a bimodal, autonomously oscillating, circadian variation of cyclic AMP content in this unicell. Rhythmic changes of the cyclic AMP level, which may reflect the transition of the cell population through the different phases of the cell division cycle (CDC) in division-phased cultures, also persisted after the culture medium had become limiting and the cells had stopped dividing. We have also shown that the free-running, circadian oscillation of cyclic AMP content displayed by nondividing cells in continuous darkness could be phase-shifted by a light signal (a property inherent to most circadian systems), in a manner that could be predicted from the phase-response curve previously obtained for the cell division rhythm in the ZC mutant. These results suggest a possible role for cyclic AMP, either as an element of the coupling pathway for the control of the CDC by the circadian oscillator, or as a ‘gear’ of the clock itself.

A cross-sectional study of platelet cyclic AMP in healthy and hypertensive pregnant women

1991 ◽  
Vol 80 (6) ◽  
pp. 549-558 ◽  
Author(s):  
E. H. Horn ◽  
J. Cooper ◽  
E. Hardy ◽  
S. Heptinstall ◽  
P. C. Rubin
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Pregnant Women ◽  
Platelet Activation ◽  
Second Messenger ◽  
Inhibitory Effects ◽  
Third Trimester ◽  
Direct Stimulation ◽  
The Third

1. Platelet activation in vivo occurs in healthy pregnant women and is more marked in women with preeclampsia. During pregnancy platelets have also been shown in vitro to be less susceptible to the inhibitory effects of prostacyclin. The cyclic nucleotide cyclic AMP has a key role as an inhibitory second messenger in platelets and mediates the inhibitory effects of prostacyclin. 2. We have studied cyclic AMP in relation to platelet behaviour in healthy pregnant women in the third trimester and in women with pregnancy-induced hypertension and pre-eclampsia. Non-pregnant young women were used as controls. 3. Pharmacological agents which increase levels of cyclic AMP were significantly less effective as inhibitors of platelet activation during pregnancy, but there was no difference between the healthy and hypertensive pregnant subjects. 4. Basal platelet cyclic AMP levels were the same in all three groups. However, the production of cyclic AMP in response to a range of adenylate cyclase stimulators was reduced during pregnancy, but again there was no difference between healthy and hypertensive pregnant subjects. 5. The reduction in platelet cyclic AMP levels in pregnancy occurred not only with those adenylate cyclase stimulators which operate via surface receptors, but also on direct stimulation of the enzyme with forskolin. 6. The most likely explanation of these observations is a reduction in the ability of the platelet adenylate cyclase enzyme to respond to stimulation in the third trimester of pregnancy. The consequent reduction in formation of the inhibitory second messenger cyclic AMP may in part be responsible for platelet activation in vivo during pregnancy. There does not appear to be a further difference in platelet cyclic AMP production in hypertensive pregnant women.

Ex vivo and in vivo studies of CME-1, a novel polysaccharide purified from the mycelia of Cordyceps sinensis that inhibits human platelet activation by activating adenylate cyclase/cyclic AMP

2014 ◽  
Vol 134 (6) ◽  
pp. 1301-1310 ◽  
Author(s):  
Wan-Jung Lu ◽  
Nen-Chung Chang ◽  
Thanasekaran Jayakumar ◽  
Jiun-Cheng Liao ◽  
Mei-Jiun Lin ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Platelet Activation ◽  
Human Platelet ◽  
Ex Vivo ◽  
Cordyceps Sinensis ◽  
In Vivo Studies

scholarly journals Dictyostelium discoideum mutant synag 7 with altered G-protein-adenylate cyclase interaction

1988 ◽  
Vol 91 (2) ◽  
pp. 287-294
Author(s):  
B.E. Snaar-Jagalska ◽  
P.J. Van Haastert
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
G Protein ◽  
Dictyostelium Discoideum ◽  
High Speed ◽  
Wild Type ◽  
High Affinity ◽  
Gtp Binding

Previous results have shown that Dictyostelium discoideum mutant synag 7 is defective in the regulation of adenylate cyclase by receptor agonists in vivo and by GTP gamma S in vitro; the guanine nucleotide activation of adenylate cyclase is restored by the high-speed supernatant from wild-type cells. Here we report that in synag 7 membranes: (1) cyclic AMP receptors had normal levels and were regulated by guanine nucleotides as in wild-type; (2) GTP binding and high-affinity GTPase were reduced but still stimulated by cyclic AMP; (3) the supernatant from wild-type cells restored GTP binding to membranes of this mutant, and partly restored high-affinity GTPase activity; (4) the supernatant of synag 7 was ineffective in these reconstitutions and did not influence GTP binding and GTPase activities in mutant or wild-type membranes. These results suggest that the defect in mutant synag 7 is located between G-protein and adenylate cyclase, and not between receptor and G-protein. A factor in the supernatant is absent in synag 7 and appears to be essential for normal GTP binding, GTPase and activation of adenylate cyclase. This soluble heat-labile factor may represent a new molecule required for receptor- and G-protein-mediated activation of adenylate cyclase.

Sign in / Sign up

Export Citation Format

Share Document