scholarly journals Time course of the uridylylation and adenylylation states in the glutamine synthetase bicyclic cascade

1993 ◽  
Vol 294 (3) ◽  
pp. 813-819 ◽  
Author(s):  
R Varón-Castellanos ◽  
B H Havsteen ◽  
M García-Moreno ◽  
E Valero-Ruiz ◽  
M Molina-Alarcón ◽  
...  
Keyword(s):  
Glutamine Synthetase ◽  
Kinetic Analysis ◽  
Time Course ◽  
Regulatory Protein ◽  
Steady States ◽  
The State ◽  
Transient Phase ◽  
Effective Sensitivity

A kinetic analysis of the glutamine synthetase bicyclic cascade is presented. It includes the dependence on time from the onset of the reaction of both the uridylylation of Shapiro's regulatory protein and the adenylylation of the glutamine synthetase. The transient phase equations obtained allow an estimation of the time elapsed until the states of uridylylation and adenylylation reach their steady-states, and therefore an evaluation of the effective sensitivity of the system. The contribution of the uridylylation cycle to the adenylylation cycle has been studied, and an equation relating the state of adenylylation at any time to the state of uridylylation at the same instant has been derived.

scholarly journals Kinetic analysis of the transient phase and steady state of open multicyclic enzyme cascades.

2005 ◽  
Vol 52 (4) ◽  
pp. 765-780 ◽  
Author(s):  
Ramón Varón ◽  
Bent H Havsteen ◽  
Edelmira Valero ◽  
Milagros Molina-Alarcón ◽  
Francisco García-Cánovas ◽  
...  
Keyword(s):  
Steady State ◽  
Data Analysis ◽  
Kinetic Analysis ◽  
Kinetic Data ◽  
Time Course ◽  
Intrinsic Value ◽  
Transient Phase ◽  
Enzyme Cascade ◽  
Rapid Equilibrium ◽  
Enzyme Cascades

This paper presents a kinetic analysis of the whole reaction course, i.e. of both the transient phase and the steady state, of open multicyclic enzyme cascade systems. Equations for fractional modifications are obtained which are valid for the whole reaction course. The steady state expressions for the fractional modifications were derived from the latter equations since they are not restricted to the condition of rapid equilibrium. Finally, the validity of our results is discussed and tested by numerical integration. Apart from the intrinsic value of knowing the kinetic behaviour of any of the species involved in any open multicyclic enzyme cascade, the kinetic analysis presented here can be the basis of future contributions concerning open multicyclic enzyme cascades which require the knowledge of their time course equations (e.g. evaluation of the time needed to reach the steady state, suggestion of kinetic data analysis, etc.), analogous to those already carried out for open bicyclic cascades.

The Time-Course of Changes in the State of Brain Monoaminergic Systems of Mice Under the Acute Hypoxia with Hypercapnia

2020 ◽  
Vol 14 (2) ◽  
pp. 136-149
Author(s):  
I. V. Karpova ◽  
V. V. Mikheev ◽  
V. V. Marysheva ◽  
N. A. Kuritcyna ◽  
E. R. Bychkov ◽  
...  
Keyword(s):  
Time Course ◽  
Acute Hypoxia ◽  
The State ◽  
Hypoxia With Hypercapnia

Symbolic Equation for the Instantaneous Amount of Substance in Linear Compartmental Systems

2011 ◽  
pp. 348-379
Author(s):  
J.M. Villalba ◽  
R. Varón ◽  
E. Arribas ◽  
R. Diaz-Sierra ◽  
F. Garcia-Sevilla ◽  
...  
Keyword(s):  
Time Course ◽  
Open Systems ◽  
Residence Times ◽  
Transient Phase ◽  
State Equations ◽  
Amount Of Substance ◽  
The Mean ◽  
Symbolic Equation ◽  
Mean Residence Times ◽  
User Friendly

The symbolic time course equations corresponding to a general model of a linear compartmental system, closed or open, with or without traps and with zero input are presented in this chapter. From here, the steady state equations are obtained easily from the transient phase equations by setting the time towards infinite. Special attention is given to the open systems, for which an exhaustive kinetic analysis has been developed to obtain important properties. Besides, the results are particularized to open systems without traps. The software COEFICOM, easy to use and with a user-friendly format of the input of data and the output of results, allows the user to obtain the symbolic expressions of the coefficients involved in the general symbolic equation and all the information necessary to derive the symbolic time course equations for closed or open systems as well as for the derivation of the mean residence times.

Changes of Acuity during Light and Dark Adaptation in the Dragonfly Compound Eye

1990 ◽  
Vol 45 (1-2) ◽  
pp. 137-142 ◽  
Author(s):  
Eric J. Warrant ◽  
Robert B. Pinter
Keyword(s):  
Dark Adaptation ◽  
Time Course ◽  
Light Adaptation ◽  
Compound Eye ◽  
Sensitivity Function ◽  
The State ◽  
Intracellular Recordings ◽  
Acceptance Angle ◽  
Angular Sensitivity ◽  
Rapid Reduction

Abstract Intracellular recordings of angular sensitivity from the photoreceptors of Aeschnid dragonflies (Hemianax papuensis and Aeschna brevistyla) are used to determine the magnitude and time course of acuity changes following alterations of the state of light or dark adaptation. Acuity is defined on the basis of the acceptance angle, Δρ (the half-width of the angular-sensitivity function). The maximally light-adapted value of Δρ is half the dark-adapted value, indicating greater acuity during light adaptation. Following a change from light to dark adaptation, Δρ increases slowly, requiring at least 3 min to reach its dark-adapted value. In contrast, the reverse change (dark to light) induces a rapid reduction of Δρ , and at maximal adapting luminances, this reduction takes place in less than 10 sec.

scholarly journals Temporal gene expression in bovine corpora lutea after treatment with PGF2alpha based on serial biopsies in vivo

Reproduction ◽  
2001 ◽  
pp. 905-913 ◽  
Author(s):  
SJ Tsai ◽  
K Kot ◽  
OJ Ginther ◽  
MC Wiltbank
Keyword(s):  
Gene Expression ◽  
Corpus Luteum ◽  
Time Course ◽  
Regulatory Protein ◽  
Corpora Lutea ◽  
Multiple Time ◽  
Lh Receptor ◽  
Time Points ◽  
Multiple Biopsies ◽  
Fp Receptor

There is growing evidence to indicate that PGF(2alpha)-induced luteolysis involves altered gene expression in the corpus luteum. Concentrations of mRNA encoding nine different gene products were quantified at three time points from corpora lutea in situ. Serial luteal biopsies (2.1-5.5 mg per biopsy) were collected using an ultrasound-guided transvaginal method and mRNA concentrations were quantified with standard curve quantitative competitive RT-PCR. In the first experiment, three luteal biopsies were collected from three heifers and analysed in multiple assays to evaluate the repeatability of the methods. Concentrations of mRNA for glyceraldehyde 3-phosphate dehydrogenase (GAPDH), PGF(2alpha) receptor (FP receptor) and LH receptor were found to be highly repeatable between assays, between multiple biopsies and between animals (coefficients of variation 1.3-17.3%). In the second experiment, heifers on days 9-11 after ovulation were assigned randomly to receive saline only (n = 6), saline with biopsies taken at t = 0, 0.5 and 4.0 h after injection (n = 6), PGF(2alpha) only (n = 6) or PGF(2alpha) with biopsies taken at t = 0, 0.5 and 4.0 h after treatment (n = 7). Biopsy alone did not change corpus luteum diameter, serum progesterone concentrations or days to next ovulation within the saline- or PGF(2alpha)-treated groups. Concentrations of mRNA for steroidogenic acute regulatory protein, FP receptor, 3beta-hydroxysteroid dehydrogenase, cytosolic phospholipase A(2) and LH receptor were decreased at 4.0 h after PGF(2alpha) injection. In contrast, PGF(2alpha) increased mRNA concentrations for prostaglandin G/H synthase-2, monocyte chemoattractant protein-1 and c-fos but the time course differed for induction of these mRNAs. Concentrations of mRNA for GAPDH did not change after PGF(2alpha) treatment. In conclusion, the techniques allowed analysis of multiple, specific mRNAs in an individual corpus luteum at multiple time points without altering subsequent luteal function. Use of these techniques confirmed that luteolysis involves both up- and downregulation of specific mRNA by PGF(2alpha).

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