scholarly journals The dynamics of gene transcription with a periodic synthesis rate

2021 ◽  
Author(s):  
Qiwen Sun ◽  
Feng Jiao ◽  
Jianshe Yu
Keyword(s):  
Gene Activation ◽  
Transcript Level ◽  
Cyclic Behavior ◽  
Synthesis Rate ◽  
Activation Process ◽  
Transcription System ◽  
Constant Rate ◽  
Real Value ◽  
The Mean ◽  
Two State Model

AbstractThe periodic transcription output is ubiquitously observed in an isogenic cell population. To understand mechanisms of cyclic behavior in transcription, we extend the gene activation process in the two-state model by assuming that the synthesis rate is periodic. We derive the analytical forms of the mean transcript level and the noise. The limits of them indicate that the mean level and the noise display periodic behaviors. Numerical examples strongly suggest that the transcription system with a periodic synthesis rate generates more noise than that with a constant rate but maintains transcription homeostasis in each period. It is also suggested that if the periodicity is not considered, the calculated noise may be greater than the real value.

scholarly journals The dynamics of gene transcription with periodic synthesis rate

2021 ◽  
Author(s):  
QIWEN SUN ◽  
Feng Jiao ◽  
Jianshe Yu
Keyword(s):  
Gene Activation ◽  
Transcript Level ◽  
Cyclic Behavior ◽  
Synthesis Rate ◽  
Activation Process ◽  
Numerical Examples ◽  
Transcription System ◽  
Constant Rate ◽  
The Mean ◽  
Two State Model

Abstract The periodic transcription output is ubiquitously observed in an isogenic cell population. To understand mechanisms of cyclic behavior in transcription, we extend the gene activation process in the two-state model by assuming the synthesis rate is periodic. We derive the analytical forms of the mean transcript level and the noise. The limits of them indicate the mean level and the noise display periodic behaviors. Our numerical examples strongly suggest that the transcription system with a periodic synthesis rate generates more noise than that with a constant rate, but maintains transcription homeostasis in each period. It also suggests that if the periodicity is not considered, the calculated noise may be greater than the correct value.

Batch Precipitation of Lead Iodide

1994 ◽  
Vol 59 (6) ◽  
pp. 1301-1304
Author(s):  
Jaroslav Nývlt ◽  
Stanislav Žáček
Keyword(s):  
Aqueous Solution ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Crystal Size ◽  
Lead Nitrate ◽  
Lead Iodide ◽  
Constant Rate ◽  
Mean Size ◽  
The Mean

Lead iodide was precipitated by a procedure in which an aqueous solution of potassium iodide at a concentration of 0.03, 0.10 or 0.20 mol l-1 was stirred while an aqueous solution of lead nitrate at one-half concentration was added at a constant rate. The mean size of the PbI2 crystals was determined by evaluating the particle size distribution, which was measured sedimentometrically. The dependence of the mean crystal size on the duration of the experiment exhibited a minimum for any of the concentrations applied. The reason for this is discussed.

Evidence for increased synthesis of lipoprotein(a) in the nephrotic syndrome.

1998 ◽  
Vol 9 (8) ◽  
pp. 1474-1481
Author(s):  
M G De Sain-Van Der Velden ◽  
D J Reijngoud ◽  
G A Kaysen ◽  
M M Gadellaa ◽  
H Voorbij ◽  
...  
Keyword(s):  
Nephrotic Syndrome ◽  
Synthesis Rate ◽  
Fractional Synthesis Rate ◽  
Lipoprotein A ◽  
Control Subjects ◽  
Apolipoprotein A ◽  
Catabolic Rate ◽  
Fractional Synthesis ◽  
The Mean

In patients with the nephrotic syndrome, markedly increased levels of lipoprotein(a) (Lp(a)) concentration have been frequently reported, and it has been suggested that this may contribute to the increased cardiovascular risk in these patients. The mechanism, however, is not clear. In the present study, in vivo fractional synthesis rate of Lp(a) was measured using incorporation of the stable isotope 13C valine. Under steady-state conditions, fractional synthesis rate equals fractional catabolic rate (FCR). FCR of Lp(a) was estimated in five patients with the nephrotic syndrome and compared with five control subjects. The mean plasma Lp(a) concentration in the patients (1749+/-612 mg/L) was higher than in control subjects (553+/-96 mg/L). Two patients were heterozygous for apolipoprotein(a) (range, 19 to 30 kringle IV domains), whereas all control subjects were each homozygous with regard to apolipoprotein(a) phenotype (range, 18 to 28 kringle IV domains). The FCR of Lp(a) was comparable between control subjects (0.072+/-0.032 pools/d) and patients (0.064+/-0.029 pools/d) despite the wide variance in plasma concentration. This suggests that differences in Lp(a) levels are caused by differences in synthesis rate. Indeed, the absolute synthetic rate of Lp(a) correlated directly with plasma Lp(a) concentration (P < 0.0001) in all subjects. The present results demonstrate that increased synthesis, rather than decreased catabolism, causes elevated plasma Lp(a) concentrations in the nephrotic syndrome.

scholarly journals Transgenic Analysis Reveals that Thyroid Hormone Receptor Is Sufficient To Mediate the Thyroid Hormone Signal in Frog Metamorphosis

2004 ◽  
Vol 24 (20) ◽  
pp. 9026-9037 ◽  
Author(s):  
Daniel R. Buchholz ◽  
Akihiro Tomita ◽  
Liezhen Fu ◽  
Bindu D. Paul ◽  
Yun-Bo Shi
Keyword(s):  
Thyroid Hormone ◽  
Hormone Receptor ◽  
Target Genes ◽  
Thyroid Hormone Receptor ◽  
Gene Activation ◽  
Inducible Promoter ◽  
Vertebrate Development ◽  
Transcription System

ABSTRACT Thyroid hormone (T3) has long been known to be important for vertebrate development and adult organ function. Whereas thyroid hormone receptor (TR) knockout and transgenic studies of mice have implicated TR involvement in mammalian development, the underlying molecular bases for the resulting phenotypes remain to be determined in vivo, especially considering that T3 is known to have both genomic, i.e., through TRs, and nongenomic effects on cells. Amphibian metamorphosis is an excellent model for studying the role of TR in vertebrate development because of its total dependence on T3. Here we investigated the role of TR in metamorphosis by developing a dominant positive mutant thyroid hormone receptor (dpTR). In the frog oocyte transcription system, dpTR bound a T3-responsive promoter and activated the promoter independently of T3. Transgenic expression of dpTR under the control of a heat shock-inducible promoter in premetamorphic tadpoles led to precocious metamorphic transformations. Molecular analyses showed that dpTR induced metamorphosis by specifically binding to known T3 target genes, leading to increased local histone acetylation and gene activation, similar to T3-bound TR during natural metamorphosis. Our experiments indicated that the metamorphic role of T3 is through genomic action of the hormone, at least on the developmental parameters tested. They further provide the first example where TR is shown to mediate directly and sufficiently these developmental effects of T3 in individual organs by regulating target gene expression in these organs.

scholarly journals Adding an Extra Dimension to What Students See through the Light Microscope: A Lab Exercise Demonstrating Critical Analysis for Microscopy Students

2011 ◽  
Vol 10 (4) ◽  
pp. 430-435
Author(s):  
Ashley Garrill
Keyword(s):  
Extra Dimension ◽  
Light Microscope ◽  
Critical Analysis ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Learning Approach ◽  
Growth Data ◽  
Constant Rate ◽  
The Mean ◽  
Biology Curriculum

This article describes an undergraduate lab exercise that demonstrates the importance of students thinking critically about what they see through a microscope. The students are given growth data from tip-growing organisms that suggest the cells grow in a pulsatile manner. The students then critique this data in several exercises that incorporate aspects of a problem-based learning approach, envisaging growth not just in two dimensions, but in three dimensions. For some cells, what appears to be pulsatile growth could also be explained by growth at a constant rate up and down in the z-axis. Depending on the diffraction pattern generated by the tip of the cell, this movement in the z-axis could go undetected. This raises the possibility that pulsatile growth seen in some species may be an artifact generated by the limitations of the light microscope. Students were subsequently asked to rate their awareness of the need to think critically about what they see through a microscope, using a scale of 1 (unaware) to 5 (very much aware). Prior to doing the lab exercise, the mean rating was 2.7; this increased to 4.4 after the lab. The students also indicated a likelihood of being more critical in their thinking in other aspects of their biology curriculum.

Photophosphorylation in Chloroplasts With Varied Proton Motive Force (PMF): II. Phosphorylation and the PMF

1982 ◽  
Vol 9 (4) ◽  
pp. 399 ◽  
Author(s):  
AB Hope ◽  
D Ranson ◽  
PG Dixon
Keyword(s):  
Time Lag ◽  
Atp Synthesis ◽  
Close Correlation ◽  
Proton Motive Force ◽  
Motive Force ◽  
Luciferase Assay ◽  
Time Lags ◽  
Constant Rate ◽  
Phosphorylation Reaction ◽  
The Mean

Measurements of ATP (luciferase assay) formed by class C pea chloroplasts in illumination times varying from 10 ms to 30 s are reported for control, + valinomycin and + nigericin conditions. ATP was made at a constant rate in controls following a time lag of a few milliseconds which varied with the illumination. Valinomycin increased the time lag to ~100 ms after which therate approached controls. Nigericin caused a gradual decrease in rate of ATP synthesis over a period of ~1s . In the steady state the rate was a different function of the transthylakoid pH difference (ΔpH) with nigericin and with valinomycin, with thresholds at ΔpH = 2.9 and 3.5 respectively. The time lags and thresholds are shown to be consistent with a threshold proton motive force (PMF) of 140-190 mV in various experiments. It is argued that this PMF corresponds to that required to poise the phosphorylation reaction to the point of ATP net synthesis at the prevailing dark phosphorylation potential. The experiments could not decide between a stoichiometry of 2 or 3 protons per ATP. Data suitable for use in constructing a kinetic model are briefly discussed. The findings generally are interpreted as showing a close correlation between phosphorylation and the PMF estimated as the mean potential energy of protons in the intrathylakoid spaces relative to the outside. It is concluded that Mitchellian coupling between bulk protons and the ATP synthetase is not yet to be discarded.

Effect of the Non-Associativity of Plasticity Model on the Cyclic Behavior of Geomaterials

2016 ◽  
Vol 725 ◽  
pp. 322-327 ◽  
Author(s):  
Fusao Oka ◽  
Sayuri Kimoto
Keyword(s):  
Effective Stress ◽  
Present Model ◽  
Cyclic Behavior ◽  
Cyclic Plasticity ◽  
Flow Rule ◽  
Plasticity Model ◽  
The Mean ◽  
Undrained Conditions ◽  
Cyclic Plasticity Model ◽  
Associated Flow Rule

The present paper proposed a cyclic plasticity model with a non-associativity parameter, i.e., the model includes non-associative flow rule and associative one. In the present model, the non-associative parameter controls the non-associativity. The model is derived based on the non-linear kinematical hardening rule with two hardening parameters for both the volumetric and deviatoric strains. From the simulation by the present model, we have found the strong non-associativity leads to the large decrease in the mean effective stress, i.e. almost zero mean effective stress during the cyclic deformations under undrained conditions while the model with associated flow rule is not.

Glass transformation phenomena in bulk and film amorphous selenium via DSC heating and cooling scans

1990 ◽  
Vol 5 (4) ◽  
pp. 789-794 ◽  
Author(s):  
S. Yannacopoulos ◽  
S.O. Kasap
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Structural Relaxation ◽  
Amorphous Selenium ◽  
Retardation Time ◽  
Transformation Kinetics ◽  
Glass Transformation ◽  
Constant Rate ◽  
The Mean

Recently there has been an emphasis on the importance of using cooling scans in DSC experiments in studying the glass transformation kinetics of glasses. The physical interpretation of the apparent activation energy from DSC heating scans has been questioned as not being meaningful. The present paper reports glass transition temperature (Tg) measurements derived from Differential Scanning Calorimetry (DSC) experiments on bulk and film amorphous selenium samples subjected to heating, at constant rate r, and cooling, at constant rate q, scans. Film samples were prepared by thermal evaporation techniques in vacuum. It is shown that for both bulk and film forms of a–Se, within experimental errors, log(r/T2gm) vs 1/Tgm plot where Tgm is the peak glass transformation temperature, and log(r) vs 1/Tgh plot, where Tgh is the glass transition onset temperature from DSC heating scans, are parallel to the log(q) vs 1/Tgc plot where Tgc is the glass transition temperature from cooling scans. Within the Hutchinson and Kovacs formulation of the glass transformation phenomenon, the results imply that the structural contribution to the mean retardation time, τ, is negligible in comparison with the temperature dependent part. The mean structural relaxation time for both bulk and film forms was found to exhibit a typical Vogel-Tammann-Fulcher type of temperature dependence. Furthermore, the structural relaxation rate was observed to be inversely proportional to the viscosity, η(T), implying that the mean structural retardation time is proportional to the viscosity, τ ∼ η. The results also confirm that the earlier studies of glass transformation kinetics in a–Se utilizing only DSC heating scans remain meaningful.

The Effect of Fin–Clipping on the Cruising Speed of Goldfish and Coho Salmon Fry

1950 ◽  
Vol 8a (2) ◽  
pp. 67-73 ◽  
Author(s):  
Roland W. Radcliffe
Keyword(s):  
Carassius Auratus ◽  
Coho Salmon ◽  
Loss Of Stability ◽  
Stability And Control ◽  
Goldfish Carassius Auratus ◽  
Salmon Fry ◽  
Constant Rate ◽  
Before And After ◽  
The Mean ◽  
And Control

Goldfish (Carassius auratus L.) and coho salmon fry (Oncorhynchus kisutch Walbaum) were acclimatized to temperatures of 20 °C. and 3 °C. respectively. The fish were placed, one at a time, once a day, for ten days, in a rotating annular chamber and the cruising speed was found. Then various fins were removed and the fish were given ten more trials. The mean cruising speeds before and after clipping were compared. The clipped fish suffered no loss in ability to swim at a constant rate. The data suggest that, for fish of a given weight and length, cruising speed is slightly improved by clipping. Any increased mortality in marked fish is due to loss of stability and control rather than loss in ability to swim steadily.

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