Endogenous rhythmicity and energy transduction. III. Time course of phytochrome action in adenylate kinase, NAD- and NADP-linked glyceraldehyde-3-phosphate dehydrogenase in Chenopodium rubrum

1973 ◽  
Vol 51 (8) ◽  
pp. 1529-1535 ◽  
Author(s):  
Silvia Frosch ◽  
Edgar Wagner
Keyword(s):  
Enzyme Activity ◽  
Adenylate Kinase ◽  
Time Course ◽  
Functional Relationship ◽  
Relative Concentration ◽  
Red Light ◽  
Endogenous Rhythm ◽  
Activated State ◽  
Endogenous Rhythmicity ◽  
Time Courses

Evidence is presented that phytochrome triggers and maintains the increase in adenylate kinase (AK) as well as NAD- and NADP-dependent glyceraldehyde-3-phosphate dehydrogenase (NAD- and NADP-GPD) activity. After cyclic germination conditions, the time courses of all three enzymes display an endogenous rhythmic increase of their activities in constant far-red light. After germination in constant conditions, NAD- and NADP-GPD activities displayed no rhythm, while AK activity increased rhythmically. Such readiness of AK activity to oscillate was taken as indication of a close functional relationship between the control mechanism(s) of the endogenous rhythm and AK activities. The time courses in NADP-GPD activity demonstrated that phytochrome acted as an on-off switch for the increase in enzyme activity and also controlled enzyme activity depending on the relative concentration of active phytochrome. There is evidence for a function of phytochrome in the "ground state" as well as in an "activated state."It is suggested that phytochrome could be coupled to endogenous rhythmicity by modulating the redox potential of the cell, while phytochrome action itself would be timed by the endogenous rhythm.

On the Regulation of Enzyme Levels (phenylalanine ammonia-lyase) in Different Organs of a Plant (Sinapis alba L.)

1971 ◽  
Vol 26 (11) ◽  
pp. 1175-1180 ◽  
Author(s):  
L. Dittes ◽  
I. Rissland ◽  
H. Mohr
Keyword(s):  
Time Course ◽  
Phenylalanine Ammonia Lyase ◽  
Enzyme Level ◽  
Red Light ◽  
Sinapis Alba ◽  
Pal Activity ◽  
Sinapis Alba L ◽  
Dramatic Difference ◽  
Dark Grown Seedling ◽  
Time Courses

The time courses of formation of the enzyme phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) mediated by far-red light (i. e. by phytochrome, Pfr) in cotyledons and hypocotyl of the mustard seedling (Sinapis alba L.) are described. While PAL activity in the cotyledons can scarcely be detected in the dark-grown seedling, the enzyme can be synthesized in the hypocotyl even in the dark. However, the degree of induction by far-red light is much greater in the cotyledons than in the hypocotyl. In the cotyledons the enzyme is not stable. The enzyme level eventually returns to nearly zero even under continuous far-red light. The time course of the level of PAL in the cotyledons (Fig. 1) can be explained by the following 3 factors (Fig. 2): 1. Induction of PAL synthesis by Pfr, whereby Pfr is continuously required; 2. Inactivation (degradation) of PAL by an inactivating principle; 3. Repression of PAL synthesis. The time course of the level of PAL in the hypocotyl is completely different (Fig. 1). An explanation of the hypocotyl data is presented which is based on the assumption that PAL synthesis in the dark and PAL synthesis mediated by phytochrome are independent phenomena which occur in different tissues of the hypocotyl. It appears that the occurrence of dark synthesis of a stable enzyme in the hypocotyl explains the seemingly dramatic difference between the cotyledons and the hypocotyl with respect to PAL.

Endogenous rhythmicity and energy transduction. I. Rhythmicity in adenylate kinase, NAD- and NADP-linked glyceraldehyde-3-phosphate dehydrogenase in Chenopodium rubrum

1973 ◽  
Vol 51 (7) ◽  
pp. 1355-1367 ◽  
Author(s):  
Silvia Frosch ◽  
Edgar Wagner ◽  
Bruce G. Cumming
Keyword(s):  
Adenylate Kinase ◽  
Strong Dependence ◽  
Phase Relationship ◽  
Spatial Separation ◽  
Period Length ◽  
Base Line ◽  
Glucose Feeding ◽  
Endogenous Rhythmicity ◽  
Time Courses ◽  
Cellular Compartments

It is demonstrated that adenylate kinase (AK) as well as NAD- and NADP-dependent glyceraldehyde-3-phosphate dehydrogenase (NAD- and NADP-GPD) display an endogenous rhythm in the time courses of their activities in constant conditions. The rhythm in AK activity has a period length of close to 30 h with two 15-h subpeaks in each 30-h period. The cycles in NAD- and NADP-GPD activity have a period length of 15 h and have an inverse phase relationship. The amplitude of the rhythm at the end of a dark period provides the base line for increase in enzyme activity in light after darkness. The increase in light is essentially the same regardless of the length of darkness. There is a differential effect of glucose feeding in light as compared to darkness. In darkness, glucose feeding increased NAD-GPD and AK activity but had no effect on NADP-GPD activity. In light, glucose caused an increase in NAD-GPD as well as AK activity over the Hoagland's controls but not in NADP-GPD, which was less than in the controls.The results are discussed in relation to a hypothesis assuming that endogenous rhythmicity might be due to the spatial separation of energy production and utilization in different cellular compartments with strong dependence on key coenzymes.

Endogenous rhythmicity and energy transduction. II. Phytochrome action and the conditioning of rhythmicity of adenylate kinase, NAD- and NADP-linked glyceraldehyde-3-phosphate dehydrogenase in Chenopodium rubrum by temperature and light intensity cycles during germination

1973 ◽  
Vol 51 (8) ◽  
pp. 1521-1528 ◽  
Author(s):  
Silvia Frosch ◽  
Edgar Wagner
Keyword(s):  
Light Intensity ◽  
Adenylate Kinase ◽  
Dark Period ◽  
Energy Transduction ◽  
Endogenous Rhythm ◽  
Chenopodium Rubrum ◽  
Germination Period ◽  
Endogenous Rhythmicity ◽  
Free Running

Endogenous rhythmicity in NADP- and NAD-linked glyceraldehyde-3-phosphate dehydrogenase (NADP- and NAD-GPD) as well as in adenylate kinase (AK) activity is initiated or synchronized during cyclic germination conditions of light and temperature, and is free-running in a dark period interrupting continuous light.There is phytochrome control of the amplitude in NADP-GPD and AK oscillations during the first hours of darkness if the beginning of the dark period is in phase with the beginning of the germination period. The endogenous rhythm acts like an "on-off" switch for potential phytochrome action. The results are discussed in relation to daily photoperiodic cycles.

Postnatal growth rate and gonadal development in circadian tau mutant hamsters reared in constant dim red light

Reproduction ◽  
2000 ◽  
pp. 327-330 ◽  
Author(s):  
RJ Lucas ◽  
JA Stirland ◽  
YN Mohammad ◽  
AS Loudon
Keyword(s):  
Time Course ◽  
Red Light ◽  
Somatic Growth ◽  
Postnatal Growth ◽  
Gonadal Development ◽  
Testicular Development ◽  
Wild Type ◽  
Similar Time ◽  
Syrian Hamsters ◽  
Body Weights

The role of the circadian clock in the reproductive development of Syrian hamsters (Mesocricetus auratus was examined in wild type and circadian tau mutant hamsters reared from birth to 26 weeks of age under constant dim red light. Testis diameter and body weights were determined at weekly intervals in male hamsters from 4 weeks of age. In both genotypes, testicular development, subsequent regression and recrudescence exhibited a similar time course. The age at which animals displayed reproductive photosensitivity, as exhibited by testicular regression, was unrelated to circadian genotype (mean +/- SEM: 54 +/- 3 days for wild type and 59 +/- 5 days for tau mutants). In contrast, our studies revealed a significant impact of the mutation on somatic growth, such that tau mutants weighed 18% less than wild types at the end of the experiment. Our study reveals that the juvenile onset of reproductive photoperiodism in Syrian hamsters is not timed by the circadian system.

scholarly journals Pseudo-streaming potentials in Necturus gallbladder epithelium. II. The mechanism is a junctional diffusion potential.

1992 ◽  
Vol 99 (3) ◽  
pp. 317-338 ◽  
Author(s):  
L Reuss ◽  
B Simon ◽  
C U Cotton
Keyword(s):  
Time Course ◽  
Bathing Solution ◽  
Intercellular Spaces ◽  
Similar Time ◽  
Streaming Potentials ◽  
Osmotic Water ◽  
Lateral Intercellular Spaces ◽  
Transepithelial Voltage ◽  
Time Courses ◽  
Good Agreement

The mechanisms of apparent streaming potentials elicited across Necturus gallbladder epithelium by addition or removal of sucrose from the apical bathing solution were studied by assessing the time courses of: (a) the change in transepithelial voltage (Vms). (b) the change in osmolality at the cell surface (estimated with a tetrabutylammonium [TBA+]-selective microelectrode, using TBA+ as a tracer for sucrose), and (c) the change in cell impermeant solute concentration ([TMA+]i, measured with an intracellular double-barrel TMA(+)-selective microelectrode after loading the cells with TMA+ by transient permeabilization with nystatin). For both sucrose addition and removal, the time courses of Vms were the same as the time courses of the voltage signals produced by [TMA+]i, while the time courses of the voltage signals produced by [TBA+]o were much faster. These results suggest that the apparent streaming potentials are caused by changes of [NaCl] in the lateral intercellular spaces, whose time course reflects the changes in cell water volume (and osmolality) elicited by the alterations in apical solution osmolality. Changes in cell osmolality are slow relative to those of the apical solution osmolality, whereas lateral space osmolality follows cell osmolality rapidly, due to the large surface area of lateral membranes and the small volume of the spaces. Analysis of a simple mathematical model of the epithelium yields an apical membrane Lp in good agreement with previous measurements and suggests that elevations of the apical solution osmolality elicit rapid reductions in junctional ionic selectivity, also in good agreement with experimental determinations. Elevations in apical solution [NaCl] cause biphasic transepithelial voltage changes: a rapid negative Vms change of similar time course to that of a Na+/TBA+ bi-ionic potential and a slow positive Vms change of similar time course to that of the sucrose-induced apparent streaming potential. We conclude that the Vms changes elicited by addition of impermeant solute to the apical bathing solution are pseudo-streaming potentials, i.e., junctional diffusion potentials caused by salt concentration changes in the lateral intercellular spaces secondary to osmotic water flow from the cells to the apical bathing solution and from the lateral intercellular spaces to the cells. Our results do not support the notion of junctional solute-solvent coupling during transepithelial osmotic water flow.

scholarly journals Sodium and calcium currents in dispersed mammalian septal neurons.

1991 ◽  
Vol 97 (2) ◽  
pp. 303-320 ◽  
Author(s):  
A Castellano ◽  
J López-Barneo
Keyword(s):  
Time Constant ◽  
Time Course ◽  
Calcium Currents ◽  
Closing Time ◽  
Patch Clamp Technique ◽  
Average Value ◽  
Time To Peak ◽  
Time Courses ◽  
Fast Activation ◽  
Septal Neurons

Voltage-gated Na+ and Ca2+ conductances of freshly dissociated septal neurons were studied in the whole-cell configuration of the patch-clamp technique. All cells exhibited a large Na+ current with characteristic fast activation and inactivation time courses. Half-time to peak current at -20 mV was 0.44 +/- 0.18 ms and maximal activation of Na+ conductance occurred at 0 mV or more positive membrane potentials. The average value was 91 +/- 32 nS (approximately 11 mS cm-2). At all membrane voltages inactivation was well fitted by a single exponential that had a time constant of 0.44 +/- 0.09 ms at 0 mV. Recovery from inactivation was complete in approximately 900 ms at -80 mV but in only 50 ms at -120 mV. The decay of Na+ tail currents had a single time constant that at -80 mV was faster than 100 microseconds. Depolarization of septal neurons also elicited a Ca2+ current that peaked in approximately 6-8 ms. Maximal peak Ca2+ current was obtained at 20 mV, and with 10 mM external Ca2+ the amplitude was 0.35 +/- 0.22 nA. During a maintained depolarization this current partially inactivated in the course of 200-300 ms. The Ca2+ current was due to the activity of two types of conductances with different deactivation kinetics. At -80 mV the closing time constants of slow (SD) and fast (FD) deactivating channels were, respectively, 1.99 +/- 0.2 and 0.11 +/- 0.03 ms (25 degrees C). The two kinds of channels also differed in their activation voltage, inactivation time course, slope of the conductance-voltage curve, and resistance to intracellular dialysis. The proportion of SD and FD channels varied from cell to cell, which may explain the differential electrophysiological responses of intracellularly recorded septal neurons.

scholarly journals Mechanisms of autoantibody production in autoimmune MRL mice.

1980 ◽  
Vol 152 (5) ◽  
pp. 1302-1310 ◽  
Author(s):  
D S Pisetsky ◽  
G A McCarty ◽  
D V Peters
Keyword(s):  
Antibody Response ◽  
Time Course ◽  
Fundamental Difference ◽  
Autoantibody Production ◽  
Quantitative Expression ◽  
Autoantibody Response ◽  
Time Courses ◽  
Antibody Levels

The quantitative expression of anti-DNA and anti-Sm antibodies has been investigated in autoimmune MRL-lpr/lpr and MRL-+/+ mice. Anti-Sm antibodies were detected in sera from 21/23 lpr/lpr and 10/16 +/+ mice, with individual animals showing striking variation in the time-course and magnitude of this autoantibody response. The peak antibody levels of the responding animals of each substrain did not differ significantly. For anti-DNA antibody, a different pattern of responsiveness was observed. Individual animals of each substrain produced very similar responses in terms of the magnitude and time-course of serum anti-DNA antibody. The differences in the peak levels of the two substrains were highly significant, with lpr/lpr mice demonstrating a much greater anti-DNA antibody response than +/+ mice. In lpr/lpr mice tested for both autoantibody systems, serum anti-DNA and anti-Sm antibodies showed distinct time-courses. These studies indicate that anti-DNA and anti-Sm antibodies are expressed independently in MRL mice, with the expression of anti-DNA, but not anti-Sm antibody markedly influenced by the presence of the 1pr gene. A fundamental difference in the mechanisms involved in the generation of anti-DNA and anti-Sm antibodies is suggested by the quantitative pattern of the two responses.

scholarly journals Rat uterine microbiochemistry: metabolic enzyme activities stimulated by 17-beta-estradiol are localized in epithelial cells.

1987 ◽  
Vol 35 (6) ◽  
pp. 657-662 ◽  
Author(s):  
J P Holt ◽  
E Rhe
Keyword(s):  
Enzyme Activity ◽  
Smooth Muscle ◽  
Epithelial Cells ◽  
Dose Response ◽  
Enzyme Activities ◽  
Time Course ◽  
Citrate Synthase ◽  
Ovariectomized Rats ◽  
Similar Response ◽  
Estradiol Treatment

Lactate dehydrogenase (LDH; EC 1.1.1.27), citrate synthase (CS; EC 4.1.3.7), and beta-hydroxyacyl-CoA-dehydrogenase (beta-OH-acyl-CoA-DH; EC 1.1.1.35) activities were determined in each of the three major cell types of rat uterus, i.e., epithelial, stromal, and smooth muscle, using quantitative microanalytical techniques. Adult ovariectomized rats were treated with 17-beta-estradiol to determine the time course and dose response (0.025-50 micrograms/300-g rat) effect of estrogen on enzyme activity of each type of uterine cell. The use of "oil well" and enzyme-cycling microtechniques to determine the time course and the dose responses of enzyme activity changes required microassays involving 1595 microdissected single cell specimens. Estradiol treatment increased epithelial LDH, CS and beta-OH-acyl-CoA-DH activity but had no effect on these enzymes in the stroma or in smooth muscle cells. The estradiol-stimulated peak enzyme activities on Day 4 in the intervention group are compared with those in the ovariectomized rat controls as follows: LDH, 44.5 +/- 3.5 vs 22.3 +/- 3.9; CS, 3.5 +/- 0.2 vs 1.5 +/- 0.6; beta-OH-acyl-CoA-H, 3.5 +/- 0.32 vs 2.2 +/- 0.2 (mean +/- standard deviation; mol/kg/hr). Stromal cell activities (LDH, 7.4 +/- 1.0; CS, 1.2 +/- 0.2; beta-OH-acyl-CoA-DH, 0.9 +/- 0.1) were significantly lower than epithelial cell levels and were similar to smooth muscle levels. Therefore, even in the ovariectomized animal epithelial cells have markedly higher metabolic activity compared with adjacent cells. The enzyme activities are expressed as moles of substrate reacting per kilogram of dry weight per hour. All three enzymes exhibited a 17-beta-estradiol-induced dose response between 0.025-0.15 micrograms/300-g rat. The three enzymes studied all had similar response patterns to estrogen. The effect of estradiol was restricted to epithelial cells, with enzyme activities increasing to maximal levels after approximately 96 hr of hormone treatment. This study therefore not only confirms the specific and differential metabolic responses of uterine cells to estradiol treatment, but clearly demonstrates that marked metabolic differences exist between epithelial cells and stromal or smooth muscle uterine cells.

scholarly journals The atypical cation-conduction and gating properties of ELIC underscore the marked functional versatility of the pentameric ligand-gated ion-channel fold

2015 ◽  
Vol 146 (1) ◽  
pp. 15-36 ◽  
Author(s):  
Giovanni Gonzalez-Gutierrez ◽  
Claudio Grosman
Keyword(s):  
Quaternary Ammonium ◽  
Time Course ◽  
Three Dimensional ◽  
Mouse Muscle ◽  
Current Decay ◽  
Quaternary Ammonium Cations ◽  
Inward Currents ◽  
Time Courses ◽  
Extracellular Side ◽  
Invariant Functional

The superfamily of pentameric ligand-gated ion channels (pLGICs) is unique among ionotropic receptors in that the same overall structure has evolved to generate multiple members with different combinations of agonist specificities and permeant-ion charge selectivities. However, aside from these differences, pLGICs have been typically regarded as having several invariant functional properties. These include pore blockade by extracellular quaternary-ammonium cations in the micromolar-to-millimolar concentration range (in the case of the cation-selective members), and a gain-of-function phenotype, which manifests as a slower deactivation time course, as a result of mutations that reduce the hydrophobicity of the transmembrane pore lining. Here, we tested this notion on three distantly related cation-selective members of the pLGIC superfamily: the mouse muscle nicotinic acetylcholine receptor (nAChR), and the bacterial GLIC and ELIC channels. Remarkably, we found that, whereas low millimolar concentrations of TMA+ and TEA+ block the nAChR and GLIC, neither of these two quaternary-ammonium cations blocks ELIC at such concentrations; instead, both carry measurable inward currents when present as the only cations on the extracellular side. Also, we found that, whereas lidocaine binding speeds up the current-decay time courses of the nAChR and GLIC in the presence of saturating concentrations of agonists, the binding of lidocaine to ELIC slows this time course down. Furthermore, whereas mutations that reduce the hydrophobicity of the side chains at position 9′ of the M2 α-helices greatly slowed the deactivation time course of the nAChR and GLIC, these mutations had little effect—or even sped up deactivation—when engineered in ELIC. Our data indicate that caution should be exercised when generalizing results obtained with ELIC to the rest of the pLGICs, but more intriguingly, they hint at the possibility that ELIC is a representative of a novel branch of the superfamily with markedly divergent pore properties despite a well-conserved three-dimensional architecture.

scholarly journals Dynamic Change in Cells Expressing IL-1β in Rat Hippocampus after Status Epilepticus

2014 ◽  
Vol 5 ◽  
pp. JCM.S13738 ◽  
Author(s):  
Satoru Sakuma ◽  
Daisuke Tokuhara ◽  
Hiroshi Otsubo ◽  
Tsunekazu Yamano ◽  
Haruo Shintaku
Keyword(s):  
Status Epilepticus ◽  
Cellular Localization ◽  
Wistar Rats ◽  
Time Course ◽  
Dynamic Change ◽  
Chronic Phase ◽  
Pyramidal Cells ◽  
Reactive Astrocytes ◽  
Time Courses ◽  
Ca3 Pyramidal Cells

Background The time course of cytokine dynamics after seizure remains controversial. Here we evaluated the changes in the levels and sites of interleukin (IL)-1β expression over time in the hippocampus after seizure. Methods Status epilepticus (SE) was induced in adult Wistar rats by means of intraperitoneal injection of kainic acid (KA). Subsequently, the time courses of cellular localization and IL-1β concentration in the hippocampus were evaluated by means of immunohistochemical and quantitative assays. Results On day 1 after SE, CA3 pyramidal cells showed degeneration and increased IL-1β expression. In the chronic phase (>7 days after SE), glial fibrillary acidic protein (GFAP)–-positive reactive astrocytes–-appeared in CA1 and became IL-1β immunoreactive. Their IL-1β immunoreactivity increased in proportion to the progressive hypertrophy of astrocytes that led to gliosis. Quantitative analysis showed that hippocampal IL-1β concentration progressively increased during the acute and chronic phases. Conclusion IL-1β affects the hippocampus after SE. In the acute phase, the main cells expressing IL-1β were CA3 pyramidal cells. In the chronic phase, the main cells expressing IL-1β were reactive astrocytes in CA1.

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