Regulation of the diurnal cycle in activity of serotonin acetyltransferase in the chick pineal gland

1978 ◽  
Vol 56 (7) ◽  
pp. 685-690 ◽  
Author(s):  
S. D. Wainwright ◽  
Lillian K. Wainwright
Keyword(s):  
Enzyme Activity ◽  
Organ Culture ◽  
Pineal Gland ◽  
Diurnal Cycle ◽  
Adenosine Receptor ◽  
Control Mechanism ◽  
Negative Control ◽  
Acetyltransferase Activity ◽  
In Vivo Effects

When chick pineal glands were explanted into organ culture at midlight phase of a diurnal cycle of illumination and incubated in the dark, they developed marked increases in serotonin acetyltransferase (acetyl coA:arylamine N-acetyltransferase; EC 2.3.1.5) activity. Either this increase in activity was inhibited or its onset was retarded in glands incubated under constant illumination.Supplements of theophylline, isobutylmethylxanthine, quinidine, and compound Ro 20-1724 (4-(3-butoxyl-4-methoxybenzyl)-2-imidazolidinone) elicited very marked increases in serotonin acetyltransferase activity in glands cultured in the dark. Levels of activity attained after 6 h in culture approached or exceeded the maximum levels attained at middark phase of the diurnal cycle in vivo. Effects of theophylline and compound Ro 20-1724 were additive.Supplements of dibutryl cAMP had little or no effect upon levels of serotonin acetyltransferase activity when tested alone or in combination with theophylline but further enhanced the increase in the level of enzyme activity elicited by Ro 20-1724. Adenosine and cAMP had little or no effect upon levels of serotonin acetyltransferase activity.It is concluded that levels of serotonin acetyltransferase activity in the chick pineal gland are regulated by a repressive, negative-control mechanism, which probably involves a membranous adenosine receptor.

Chick pineal serotonin acetyltransferase: a diurnal cycle maintained in vitro and its regulation by light

1979 ◽  
Vol 57 (6) ◽  
pp. 700-709 ◽  
Author(s):  
S. D. Wainwright ◽  
Lillian K. Wainwright
Keyword(s):  
Enzyme Activity ◽  
Diurnal Cycle ◽  
Prolonged Exposure ◽  
Continuous Illumination ◽  
Constant Darkness ◽  
Light Cycle ◽  
Acetyltransferase Activity ◽  
Lighting Conditions

We have reproduced in vitro the diurnal cycles in levels of serotonin acetyltransferase activity found in the chick pineal gland in vivo. The more closely the lighting conditions of culture matched those under which the birds were raised, the closer was the similarity between cycles in levels of enzyme activity in vitro and in vivo. Repetitive cycles in levels of acetyltransferase activity persisted in culture for at least 4 days under a diurnal cycle of illumination, and at least 2 days in continuous darkness. When glands were explanted into culture in the light phase of a cycle, short periods of further exposure to light markedly stimulated subsequent increase of acetyltransferase in the dark (after a short lag). Prolonged exposure to light in culture markedly inhibited increase of enzyme activity. Cycles in the levels of enzyme activity in glands cultured under altered light cycles were regulated primarily by changes in illumination. However, the endogenous biological 'clock' remained at least partly entrained to the original light cycle. Increase of acetyltransferase activity in vitro was markedly stimulated by theophylline plus compound Ro. 20.1724 (4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone) under all lighting conditions. Kinetics (to the time of attaining maximum levels in situ) of the increase under diurnal lighting and in constant darkness were indistinguishable from those in vivo. A high concentration of dl-propranolol markedly stimulated an increase in acetyltransferase activity in glands cultured in constant darkness but had little effect on glands under diurnal lighting or continuous illumination.

scholarly journals Allomorphy as a mechanism of post-translational control of enzyme activity

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Henry P. Wood ◽  
F. Aaron Cruz-Navarrete ◽  
Nicola J. Baxter ◽  
Clare R. Trevitt ◽  
Angus J. Robertson ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Translational Control ◽  
Environmental Changes ◽  
Control Mechanism ◽  
Enzyme Regulation ◽  
Peptide Bond ◽  
Lag Phase ◽  
Phosphoryl Transfer ◽  
Fine Control

Abstract Enzyme regulation is vital for metabolic adaptability in living systems. Fine control of enzyme activity is often delivered through post-translational mechanisms, such as allostery or allokairy. β-phosphoglucomutase (βPGM) from Lactococcus lactis is a phosphoryl transfer enzyme required for complete catabolism of trehalose and maltose, through the isomerisation of β-glucose 1-phosphate to glucose 6-phosphate via β-glucose 1,6-bisphosphate. Surprisingly for a gatekeeper of glycolysis, no fine control mechanism of βPGM has yet been reported. Herein, we describe allomorphy, a post-translational control mechanism of enzyme activity. In βPGM, isomerisation of the K145-P146 peptide bond results in the population of two conformers that have different activities owing to repositioning of the K145 sidechain. In vivo phosphorylating agents, such as fructose 1,6-bisphosphate, generate phosphorylated forms of both conformers, leading to a lag phase in activity until the more active phosphorylated conformer dominates. In contrast, the reaction intermediate β-glucose 1,6-bisphosphate, whose concentration depends on the β-glucose 1-phosphate concentration, couples the conformational switch and the phosphorylation step, resulting in the rapid generation of the more active phosphorylated conformer. In enabling different behaviours for different allomorphic activators, allomorphy allows an organism to maximise its responsiveness to environmental changes while minimising the diversion of valuable metabolites.

Adrenergic control of pineal N-acetyltransferase activity: developmental aspects.

1977 ◽  
Vol 233 (3) ◽  
pp. E141
Author(s):  
A Yuwiler ◽  
D C Klein ◽  
M Buda ◽  
J L Weller
Keyword(s):  
Enzyme Activity ◽  
Adrenergic Receptors ◽  
Neonatal Rat ◽  
Adrenergic Stimulation ◽  
Catecholamine Synthesis ◽  
Acetyltransferase Activity ◽  
Presynaptic Mechanisms ◽  
Adrenergic Control

The activity of pineal N-acetyltransferase in the neonatal rat does not exhibit the large daily rhythm seen in the adult and is intermediate between the low day and high night adult values. These intermediate values appear to result from adrenergic stimulation. Blockade of adrenergic receptors or of catecholamine synthesis results in a decrease in enzyme activity in vivo. In vitro studies provide additional evidence of a completely developed postsynaptic adrenergic control system for pineal N-acetyltransferase activity at birth. Our observations indicate that the appearance of a circadian rhythm in pineal N-acetyltransferase at the end of the first week of life reflects the development of presynaptic mechanisms and structures necessary for the control of catecholamine release and uptake. These events follow the developmental appearance of the postsynaptic mechanisms required to mediate the adrenergic-cycle AMP regulation of pineal N-acetyltransferase activity, which can be detected prior to birth.

A model for studies on the response of the ventral prostate to oestrogens

1981 ◽  
Vol 97 (1) ◽  
pp. 125-136 ◽  
Author(s):  
J. J. Corrales ◽  
P. A. Høisaeter ◽  
N. Kadohama ◽  
G. P. Murphy ◽  
A. A. Sandberg
Keyword(s):  
Body Weight ◽  
Organ Culture ◽  
Age Differences ◽  
Oestrogen Receptor ◽  
Direct Interaction ◽  
Ventral Prostate ◽  
Target Tissue ◽  
The Mean ◽  
In Vivo Effects

Abstract. The effects of oestrogen administration on the weight of ventral and dorsolateral prostates were studied in castrated rats of Wistar-Furth and Copenhagen strains. Direct effect of oestradiol (Oe2) on prostatic tissue was also investigated in organ culture. Oe2-treated animals received daily injections of 50 μg for 7 days. Control animals were treated with the vehicle only (peanut oil). In 4 month old Copenhagen rats the mean weight of the ventral prostates (42.4 ± 9.4 mg/100 g body weight) was significantly higher than that in the control animals (19.9 ± 4.6 mg/100 g body weight, P < 0.0001). No such differences were observed in older Copenhagen rats (9 months old) or Wistar-Furth rats (3 and 6 months old). Thus, this effect of Oe2 on ventral prostate seems both strain specific and age specific. Similar strain and age differences in the Oe2 effect were found in the dorsolateral prostate, but to a smaller extent. Direct interaction of Oe2 with target tissue was demonstrated in culture as evidenced by the ability of the steroid to prevent regression in explants derived from prostates of Copenhagen rats. The in vivo effects of Oe2 on the prostate weights could not be explained by differences in specific androgen or oestrogen receptor contents or in testosterone (T) metabolism. However, the prostates of younger Copenhagen rats differed from those of all other groups in three respects: 1) they contained high levels of oestramustine binding protein (OeBP), 2) they had the highest amount of uptake of radioactivity into the nuclear residue, and 3) their histological picture was characterized by diffuse stromal architecture having the appearance of oedematous tissue.

scholarly journals In vivo enzyme activity and induction of DNA damage in Swiss albino male mice by automobile waste leachate

2018 ◽  
Vol 10 (2) ◽  
pp. 285-295
Author(s):  
Abass Toba Anifowoshe ◽  
Oluyinka Ajibola Iyiola ◽  
Temitope Fatima Olafimihan ◽  
Segun Olayinka Oladipo ◽  
Sunday Frank Yakubu ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Positive Control ◽  
Negative Control ◽  
Motor Vehicles ◽  
Genetic Constitution ◽  
Male Mice ◽  
Serum Enzyme ◽  
Sperm Abnormality ◽  
Waste Leachate

The rapid growth of motor vehicles use, together with poor waste disposal, produce environmental and biological threats. We evaluated the genotoxicity and enzyme activity of simulated automobile waste leachate in Swiss albino male mice (Mus musculus). Four mice per group were intraperitoneally treated with four leachate concentrations (10%, 15%, 20% and 25% v/v: simulant (IOASL)/distilled water), as well as a negative control (0.5mL UILSL); and a positive control (cyclophosphamide 20mg/Kg body weight) for five consecutive days. There was a concentration-dependent increase in sperm abnormality compared to the negative control (except at 10% and 15%; p<0,05). Heavy metal (Pb, Cd, As, Hg, Cr, Cu, Fe and Zn) exceeded permissible limits for waste water. Significant variability was also recorded in liver serum enzyme activity (AST, ALP, ALT and ALB) and in the frequencies of micronuclei (p<0,05). The interaction of some of these components with the genetic constitution of the cell during spermatogenesis might be responsible for the abnormalities. 

Lactase synthesis is pretranslationally regulated in protein-deficient pigs fed a protein-sufficient diet

2001 ◽  
Vol 280 (4) ◽  
pp. G621-G628 ◽  
Author(s):  
Mary A. Dudley ◽  
Patricia A. Schoknecht ◽  
Alden W. Dudley ◽  
Lan Jiang ◽  
Ronaldo P. Ferraris ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Relative Abundance ◽  
Elongation Factor ◽  
Protein Malnutrition ◽  
Mrna Abundance ◽  
Synthesis Rate ◽  
Isocaloric Diets ◽  
And Control ◽  
In Vivo Effects

The in vivo effects of protein malnutrition and protein rehabilitation on lactase phlorizin hydrolase (LPH) synthesis were examined. Five-day-old pigs were fed isocaloric diets containing 10% (deficient, n = 12) or 24% (sufficient, n = 12) protein. After 4 wk, one-half of the animals in each dietary group were infused intravenously with [13C1]leucine for 6 h, and the jejunum was analyzed for enzyme activity, mRNA abundance, and LPH polypeptide isotopic enrichment. The remaining animals were fed the protein-sufficient diet for 1 wk, and the jejunum was analyzed. Jejunal mass and lactase enzyme activity per jejunum were significantly lower in protein-deficient vs. control animals but returned to normal with rehabilitation. Protein malnutrition did not affect LPH mRNA abundance relative to elongation factor-1α , but rehabilitation resulted in a significant increase in LPH mRNA relative abundance. Protein malnutrition significantly lowered the LPH fractional synthesis rate (FSR; %/day), whereas the FSR of LPH in rehabilitated and control animals was similar. These results suggest that protein malnutrition decreases LPH synthesis by altering posttranslational events, whereas the jejunum responds to rehabilitation by increasing LPH mRNA relative abundance, suggesting pretranslational regulation.

scholarly journals Some properties of the uridine diphosphate glucuronyltransferase activity synthesizing thio-β-d-glucuronides

1973 ◽  
Vol 131 (1) ◽  
pp. 139-147 ◽  
Author(s):  
H. P. A. Illing ◽  
G. J. Dutton
Keyword(s):  
Enzyme Activity ◽  
Phenolic Compounds ◽  
Organ Culture ◽  
Tissue Distribution ◽  
Glucuronic Acid ◽  
Uridine Diphosphate ◽  
Intracellular Location ◽  
Gunn Rats ◽  
Optimum Ph

1. Some properties of the UDP-glucuronyltransferase synthesizing thio-β-d-glucuronides were investigated and compared with those of the enzyme synthesizing the O-glucuronides of analogous phenols. 2. Enzyme activity was generally similar for both classes of substrate in tissue distribution, intracellular location, optimum pH, perinatal development and induction by organ culture or by phenobarbital. 3. Certain differences were noted between the two types of activity in behaviour on storage and on activation, in kinetic behaviour and in distribution between Wistar and Gunn rats; the Gunn rats were not deficient in hepatic UDP-glucuronyltransferase activity towards o-aminothiophenol. 4. These differences are no greater than those exhibited in the synthesis of various O-glucuronides; therefore thiolic substrates could compete in vivo with phenolic compounds for access to the UDP-glucuronyltransferase complex as well as for UDP-glucuronic acid.

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