scholarly journals Phase shifting the circadian rhythm of neuronal activity in the isolated Aplysia eye with puromycin and cycloheximide. Electrophysiological and biochemical studies.

1976 ◽  
Vol 68 (4) ◽  
pp. 359-384 ◽  
Author(s):  
B S Rothman ◽  
F Strumwasser
Keyword(s):  
Protein Synthesis ◽  
Circadian Rhythm ◽  
Light Response ◽  
Compound Action Potential ◽  
Phase Shifting ◽  
Constant Darkness ◽  
Leucine Incorporation ◽  
Drug Treatments ◽  
Dose Dependent ◽  
Electrophysiological Effects

The effects of pulse application of puromycin (PURO) or cycloheximide (CHX) were tested on the circadian rhythm (CR) of spontaneous compound action potential (CAP) activity in the isolated Aplysia eye. CAP activity was recorded from the optic nerve in constant darkness at 15degreesC. PURO pulses (6, 12 h; 12--134 mug/ml) and CHX pulses (12 h, 500--2,000 mug/ml) caused dose-dependent phase delays in the CR when administered during projected night. PURO pulses (6 h, 125 mug/ml) caused phase advances when given during projected day and caused phase delays when given during projected night. In biochemical experiments PURO (12 h, 20 mug/ml) and CHX (12 h, 500 mug/ml) inhibited leucine incorporation into the eye by about 50%. PURO (12 h; 50, 125 mug/ml) also changed the molecular weight distribution of proteins synthesized by the eye during the pulse. The effect of PURO (12 h, 125 mug/ml) on the level of incorporation was almost completely reversible within the next 12 h but the phase-shifted eye showed an latered spectrum of proteins for up to 28 h after the pulse. In electrophysiological experiments spontaneous CAP activity and responses to light were measured before, during, and after drug treatments. In all, eight parameters in three periods were analyzed quantitatively. Of these 24 indices, only 3 showed significant changes. PURO increased spontaneous CAP frequency by 67% 0-7 h after the drug pulse and increased the CAP amplitude of the tonic light response by 23% greater than 7 h after the pulse. CHX increased the intraburst spontaneous CAP frequency by 33% during the pulse and CAP frequency of the tonic light response by 32% 0-7 h after the pulse. The above data indicate that phase-shifting doses of PURO and CHX inhibit protein synthesis in the eye without causing adverse electrophysiological effects, and suggest that protein synthesis is involved in the production of the CR of the isolated Aplysia eye.

The Circadian Rhythm of Flight Activity of the Mosquito Anopheles Gambiae: The Light-Response Rhythm

1972 ◽  
Vol 57 (2) ◽  
pp. 337-346
Author(s):  
M. D. R. JONES ◽  
C. M. CUBBIN ◽  
D. MARSH
Keyword(s):  
Circadian Rhythm ◽  
Phase Response Curve ◽  
Light Response ◽  
Flight Activity ◽  
Phase Shifting ◽  
Apparent Effect ◽  
Maximum Phase ◽  
Activity Peak ◽  
Mosquito Anopheles Gambiae ◽  
Normal Light

1. In sugar-fed A. gambiae females, light may affect flight activity directly or by changing the phase of the circadian rhythm; both responses depend on the phase of the rhythm. 2. The phase-response curve (1 h, 70 lux, signals given in the first cycle in DD following LD 12:12) shows a sharp swing, at about 3 h after normal light-off, from a maximum phase-delay to a maximum phase-advance, each of about 2 h. When signals are given at this time, phase re-setting is very variable; cyclical activity continues but the individuals are out of phase. 3. Phase shifting appears to be a function of the energy of the signal. A 5 min, 70 lux signal has no apparent effect. The effect of a 1 h signal increases with intensity, up to at least 500 lux, but does not appear to be significant below 10 lux. 4. Light normally inhibits flight activity, but there is a burst of activity at light-on (light-on response) if it occurs during the active half of the cycle following the initial activity peak. A vigorous light-on response occurs even at the lowest intensity used (0.3 lux).

Increased Protein Synthesis by Human Platelets during Phagocytosis of Latex Particles in Vitro

1976 ◽  
Vol 35 (02) ◽  
pp. 350-357 ◽  
Author(s):  
Hana Bessler ◽  
Galila Agam ◽  
Meir Djaldetti
Keyword(s):  
Protein Synthesis ◽  
Fold Increase ◽  
Human Platelets ◽  
Polystyrene Latex ◽  
Latex Particles ◽  
The Third ◽  
Platelet Protein ◽  
Dose Dependent ◽  
Phagocytotic Activity

SummaryA three-fold increase of protein synthesis by human platelets during in vitro phagocytosis of polystyrene latex particles was detected. During the first two hours of incubation, the percentage of phagocytizing platelets and the number of latex particles per platelet increased; by the end of the third hour, the first parameter remained stable, while the number of latex particles per cell had decreased.Vincristine (20 μg/ml of cell suspension) inhibited platelet protein synthesis. This effect was both time- and dose-dependent. The drug also caused a decrease in the number of phagocytizing cells, as well as in their phagocytotic activity.

EFFECT OF ACTINOMYCIN D ON TSH-INDUCED STIMULATION OF THYROIDAL PROTEIN SYNTHESIS IN THE RAT

1974 ◽  
Vol 77 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Gustav Wägar
Keyword(s):  
Protein Synthesis ◽  
Actinomycin D ◽  
The Other ◽  
Leucine Incorporation ◽  
Short Term ◽  
Other Hand ◽  
Thyroid Glands ◽  
Translational Level ◽  
Stimulation Of

ABSTRACT Whether the short-term regulation of thyroidal protein synthesis by TSH occurs at the transcriptional or the translational level was tested by measuring the effect of actinomycin D (act D) on the TSH-induced stimulation of L-14C-leucine incorporation into the thyroidal proteins of rats. TSH was injected 6 h before the rats were killed. The thyroid glands were then removed and incubated in vitro in the presence of L-14C-leucine for 2 h. The pronounced stimulation of leucine incorporation in the TSH-treated animals was depressed as compared with controls but still significant even when the animals had been pre-treated with 100 μg act D 24 and 7 h before sacrifice. On the other hand, act D strongly decreased incorporation of 3H-uridine into RNA. Short-term regulation of thyroidal protein synthesis by TSH appears to be partly but not wholly dependent on neosynthesis of RNA. Hence regulation may partly occur at the translation level of protein synthesis.

scholarly journals rdgE: A Novel Retinal Degeneration Mutation in Drosophila melanogaster

Genetics ◽  
1996 ◽  
Vol 144 (1) ◽  
pp. 127-138
Author(s):  
Troy Zars ◽  
David R Hyde
Keyword(s):  
Electron Microscopy ◽  
Retinal Degeneration ◽  
Light Response ◽  
Neuronal Membrane ◽  
Constant Darkness ◽  
Multivesicular Bodies ◽  
Photoreceptor Degeneration ◽  
Transmission Electron ◽  
Phototransduction Cascade ◽  
Membrane Biosynthesis

Abstract We report isolating the Drosophila retinal degeneration E (rdgE) mutation. The hypomorphic rdgE  1 allele causes rapid photoreceptor degeneration in light and a slower rate of degeneration when the flies are raised in constant darkness. The rdgE  1 flies exhibited an electrophysiological light response that decreased with age, coinciding with the degeneration. This suggests that degeneration caused the loss of the light response. We determined that the ninaE (rhodopsin) mutation, but not norpA [phospholipase C (PLC)], slowed the rdgE-dependent degeneration. This was consistent with the light-enhanced degeneration, but revealed that the degeneration is independent of the PLC-mediated phototransduction cascade. Transmission electron microscopy revealed that rdgE  1 photoreceptors exhibited a number of vesicular transport defects including unpacking/vesiculation of rhabdomeres, endocytosis of novel vesicles by photoreceptors, a buildup of very large multivesicular bodies, and an increased amount of rough endoplasmic reticulum. We determined that the rdgE null phenotype is a late embryonic lethality. Therefore, rdgE  + is required in cells outside of the retina, quite possibly in a large number of neurons. Thus, rdgE may define a mutational class that exhibits both light-enhanced retinal degeneration and a recessive null lethality by perturbing neuronal membrane biosynthesis and/or recycling.

A circadian rhythm in the locomotive behaviour of the giant garden slug Limax maximus

1977 ◽  
Vol 66 (1) ◽  
pp. 47-64
Author(s):  
P. G. Sokolove ◽  
C. M. Beiswanger ◽  
D. J. Prior ◽  
A. Gelperin
Keyword(s):  
Circadian Rhythm ◽  
Locomotor Activity ◽  
Phase Angle ◽  
Circadian Rhythmicity ◽  
Constant Darkness ◽  
Light Cycle ◽  
Circadian Activity ◽  
Locomotor Rhythm ◽  
Activity Peak ◽  
Limax Maximus

The locomotor activity of the garden slug Limax maximus was examined for components of circadian rhythmicity. Behavioural (running wheel) studies clearly demonstrated that the activity satisfies the principal criteria of circadian rhythmicity. In constant darkness at a constant temperature, the locomotor activity freeran with a period of about 24 h (range 23-6-24-6 h). The rhythm was also expressed in constant light with a period for individual slugs that tended to be shorter in LL than in DD. The period of the rhythm was temperature compensated (11–5-21-5 degrees C) with a Q10 approximately equal to 1–00. The locomotor rhythm could be entrained to 24 h LD cycles such that the circadian activity peak occurred during the dark. The phase angle between the onset of activity and lights-off was not fixed, but was a function of the photoperiod of the entraining light cycle.

Use of an in Vitro Protein Synthesizing System to Test the Mode of Action of Chloracetamides

Weed Science ◽  
1980 ◽  
Vol 28 (3) ◽  
pp. 334-340 ◽  
Author(s):  
Luanne M. Deal ◽  
J. T. Reeves ◽  
B. A. Larkins ◽  
F. D. Hess
Keyword(s):  
Protein Synthesis ◽  
Sand Culture ◽  
Leucine Incorporation ◽  
Insoluble Protein ◽  
In Vitro System ◽  
A Cell ◽  
Protein Incorporation ◽  
Vitro Protein

The effects of chloracetamides on protein synthesis were studied both in vivo and in vitro. Four chloracetamide herbicides, alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], CDAA (N–N-diallyl-2-chloroacetamide), and propachlor (2-chloro-N-isopropylacetanilide) were tested for inhibition of [3H]-leucine incorporation into protein. Incorporation of3H-leucine into trichloroacetic acid (TCA)-insoluble protein was inhibited in oat (Avena sativaL. ‘Victory’) seedlings grown in sand culture and treated 12 h at 1 × 10−4M with these chloracetamides. The herbicides were also tested in a cell-free protein synthesizing system containing polyribosomes purified from oat root cytoplasm. These herbicides had no effect on the rates of polypeptide elongation nor on the synthesis of specific polypeptides when herbicides (1 × 10−4M) were added directly to the system. Polypeptide formation was inhibited 89% when 1 × 10−4M cycloheximide was added during translation. Cytoplasmic polyribosomes were isolated from oat roots treated 12 h with 1 × 10−4M herbicide. Translation rates and products were not altered when these polyribosomes were added to the in vitro system. Protein synthesis is inhibited when tested in an in vivo system; however, the inhibition does not occur during the translation of mRNA into protein.

scholarly journals The acylation of proteins by xenobiotic amphipathic carboxylic acids in cultured rat hepatocytes

1988 ◽  
Vol 254 (1) ◽  
pp. 39-44 ◽  
Author(s):  
R Hertz ◽  
J Bar−Tana
Keyword(s):  
Protein Synthesis ◽  
Carboxylic Acids ◽  
Mode Of Action ◽  
Biological Effects ◽  
Rat Hepatocytes ◽  
Protein Adducts ◽  
Cultured Rat Hepatocytes ◽  
Acylated Proteins ◽  
Dose Dependent ◽  
Protein Acylation

Three xenobiotic amphipathic carboxylates, namely MEDICA 16, nafenopin and bezafibrate, which differ remarkably in their hydrophobic backbones, were found to acylate membrane and cytosolic liver proteins in cultured rat hepatocytes. The acylation patterns observed were time- and dose-dependent, and the acylated residue consisted of the original xenobiotic. The acylation patterns generated by the three xenobiotic carboxylates included common proteins which were acylated by the three xenobiotics (e.g. proteins of 32, 52, 56 and 72 kDa) as well as unique proteins which were specifically acylated by the respective xenobiotics. The acylation of liver proteins by either MEDICA 16 or nafenopin remained unaffected under conditions where protein synthesis was completely inhibited by cycloheximide. Protein acylation thus offers a common mode of action of xenobiotic amphipathic carboxylates, which may, however, result in diverse xenobiotyl-protein adducts. The xenobiotyl-acylated proteins might be involved in triggering some of the biological effects exerted by xenobiotic amphipathic carboxylates employed as hypolipidaemic effectors, peroxisomal proliferators or preadipocyte convertors.

Effect of somatostatin on circadian rhythms of firing and 2-deoxyglucose uptake in rat suprachiasmatic slices

1993 ◽  
Vol 265 (5) ◽  
pp. R1199-R1204 ◽  
Author(s):  
T. Hamada ◽  
S. Shibata ◽  
A. Tsuneyoshi ◽  
K. Tominaga ◽  
S. Watanabe
Keyword(s):  
Circadian Rhythm ◽  
Vasoactive Intestinal Polypeptide ◽  
Phase Changes ◽  
Circadian Clocks ◽  
Constant Darkness ◽  
Phase Resetting ◽  
Firing Activity ◽  
Light Pulses ◽  
Circadian Time

In mammals, the suprachiasmatic nucleus (SCN) of the hypothalamus appears to act as a circadian clock. The SCN vasoactive intestinal polypeptide-like immunoreactive neurons, which may act to mediate photic information in the SCN, receive input from neurons immunoreactive for somatostatin (SST). Therefore we investigated the role of SST as a transmitter for entrainment by analyzing the phase-resetting effect of SST on the circadian rhythm of SCN firing activity. Perfusion of SST increased 2-deoxyglucose uptake at circadian time (CT) 18, but not at CT6. A 1-h or 15-min treatment with SST produced phase delays when it was administered at CT13-14 and phase advances at CT22-23. Thus SST-induced phase changes are similar to those for light pulses to animals under constant darkness. The present findings suggest that SST is a transmitter for mediating information of entrainment to circadian clocks within the SCN.

Dose-response curves of effects of insulin on leucine kinetics in humans

1986 ◽  
Vol 251 (3) ◽  
pp. E334-E342 ◽  
Author(s):  
P. Tessari ◽  
R. Trevisan ◽  
S. Inchiostro ◽  
G. Biolo ◽  
R. Nosadini ◽  
...  
Keyword(s):  
Insulin Infusion ◽  
Leucine Incorporation ◽  
Dependent Manner ◽  
Carbon Oxidation ◽  
Response Curves ◽  
Leucine Kinetics ◽  
Dose Dependent ◽  
Kinetics In Vivo ◽  
Infusion Period

To determine the effects of physiological and pharmacological insulin concentrations on leucine-carbon kinetics in vivo, eight postabsorptive normal volunteers were infused with L-[4,5-3H]leucine and alpha-[1-14C]ketoisocaproate (KIC). Insulin concentrations were sequentially raised from 8 +/- 1 to 43 +/- 6 and 101 +/- 14 and to 1,487 +/- 190 microU/ml, while maintaining euglycemia with adequate glucose infusions. At the end of each 140-min insulin-infusion period, steady-state estimates of leucine and KIC rates of appearance (Ra), KIC (approximately leucine-carbon) oxidation, nonoxidized leucine-carbon flux [an index of leucine incorporation into protein (Leu----P)], and leucine and KIC interconversion rates were obtained. After the three insulin infusions, leucine Ra decreased by a maximum of approximately 20%. KIC Ra decreased by a maximum of approximately 50%. The sum of leucine plus KIC Ra in the basal state was 2.59 +/- 0.24 mumol X kg-1 X min-1 and decreased by approximately 30% at the maximal insulin concentrations. KIC oxidation decreased by a maximum of approximately 65%. Leu----P did not increase after hyperinsulinemia. Interconversion rates were promptly and markedly suppressed by 50-70%. Leucine clearance increased by approximately 120%. We conclude that euglycemic hyperinsulinemia, at physiological and pharmacological concentrations, decreased leucine and KIC concentrations, leucine-carbon turnover and oxidation, and leucine and KIC interconversions in a dose-dependent manner in vivo.

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