Identification of calmodulin in Acetabularia: its distribution and physiological significance

1987 ◽  
Vol 87 (2) ◽  
pp. 337-347
Author(s):  
GENEVIÈVE COTTON ◽  
THÊRÈSE VANDEN DRIESSCHE
Keyword(s):  
Circadian Rhythm ◽  
Rapid Growth ◽  
Physiological Significance ◽  
Physiological Effects ◽  
Circadian Cycle ◽  
Polyacrylamide Gels ◽  
Growth Phases ◽  
Low Concentration ◽  
Wet Weight

In order to test whether calmodulin is present in Acetabularia, material was isolated from this alga, using the chlorpromazine affinity method. This resulted in the purification of a protein with the correct mobility on SDS-polyacrylamide gels. This protein reacted with anti-calmodulin in dot blots, using an immunogold, silver-enhanced method, so we conclude that calmodulin is present in the alga, although at a very low concentration (200–450 pg per gram wet weight). The localization of calmodulin was studied, using fluphenazine fluorescence. The pattern is described; the chief feature being the concentration of fluorescence towards the tip during both the slow and the rapid growth phases. Fluorescence is also observed at the insertion points of hairs on the stalk and decreases in intensity between hairs of successive order. The apical fluorescence vanishes when cap formation begins. The localization of calmodulin parallels that of calcium studied by means of chlorotetracycline and aequorin. Expecting inhibitors of calmodulin to produce physiological effects, we studied the growth of whole and anucleate Acetabularia in the presence of trifluoperazine (TFP). TFP severely inhibited growth and cap formation, as did lanthanum. A circadian rhythm of sensitivity to these inhibitors was found. The hypothesis is put forward that calcium and calmodulin are important during a critical photosensitive phase of the circadian cycle.

Advance shift of feeding circadian rhythm induced by obesity progression in Zucker rats

1992 ◽  
Vol 263 (6) ◽  
pp. R1169-R1175 ◽  
Author(s):  
K. Fukagawa ◽  
T. Sakata ◽  
H. Yoshimatsu ◽  
K. Fujimoto ◽  
K. Uchimura ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Circadian Rhythms ◽  
Least Squares ◽  
Developmental Stages ◽  
Ingestive Behavior ◽  
Zucker Rats ◽  
Circadian Cycle ◽  
Dark Cycle ◽  
Behavioral Measures ◽  
Obese Rats

To determine the relation between the circadian rhythm of ingestive behavior and the progression of obesity in Zucker rats, ingestion and ambulation were analyzed at four different developmental stages. The obese rats were disrupted gradually in nocturnal patterns of feeding, drinking, and ambulation with the progression of obesity, although the lean littermates maintained the patterns during whole test periods. Analysis of autocorrelogram revealed that circadian rhythms of those behaviors remained throughout the whole test periods. Least-squares spectrum ascertained the following. 1) The obese made advance shift of acrophases in feeding and drinking circadian cycles, but not in ambulation. 2) Amplitudes in those behavioral measures decreased with the progression of obesity. 3) Mesor in the obese feeding was not affected, although that in the lean feeding decreased. The findings indicate that disruption of the light-dark cycle in ingestion of the obese was not due to disappearance of circadian rhythm but to transformation by both decreased amplitude and advance shift of the circadian cycle.

scholarly journals Increase in 6-Hydroxymelatonin Excretion in Humans during Ascent to High Altitudes

2004 ◽  
Vol 89 (9) ◽  
pp. 4388-4390 ◽  
Author(s):  
Herwig Frisch ◽  
Franz Waldhauser ◽  
Thomas Waldhör ◽  
Andrea Müllner-Eidenböck ◽  
Pritam Neupane ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Circadian Rhythms ◽  
Pineal Gland ◽  
Diurnal Variation ◽  
Healthy Volunteers ◽  
High Altitude ◽  
Physiological Role ◽  
Physiological Significance ◽  
High Altitudes ◽  
Lower Altitude

Melatonin (MLT), the pineal gland hormone involved in the regulation of circadian rhythms, shows characteristic diurnal variation. Its physiological role in humans is not clear. Exposure to high altitudes may disrupt the circadian rhythm and lead to various endocrine changes. MLT in humans has not been studied under these conditions. Urinary 6-hydroxy-MLT sulfate (aMT6s) excretion was analyzed during the day (0700–2200 h) and night (2200–0700 h) phases. A cohort of 33 healthy volunteers, aged 19–65 yr, was studied during an ascent to a high altitude in the Himalayas on three occasions (at a lower altitude, at 3400 m, and after reaching maximal altitudes of 5600–6100 m). aMT6s excretion during the daytime remained unchanged during exposure to high altitudes. As expected, nocturnal values were higher than diurnal values at each point in time. However, there was a significant increase in nocturnal MLT excretion after the ascent to high altitudes. Ascent to high altitudes is associated with increased nocturnal excretion of aMT6s. The mechanism and physiological significance of this MLT increase are unclear.

scholarly journals Le abitudini al tempo del Coronavirus

2020 ◽  
Vol 32 (1) ◽  
pp. 69-72
Author(s):  
David Mariani ◽  
Raffaele Picco ◽  
Francesca Capitanini ◽  
Alex Porciani ◽  
Marco Lombardi ◽  
...  
Keyword(s):  
Physical Activity ◽  
Circadian Rhythm ◽  
Physiological Effects ◽  
Correct Information ◽  
Isolation Effects ◽  
Difficult Times

Introduction: The COVID-19 pandemic that hit the humankind in December 2019, is steering quick and drastic changes to our habits. The goal of our research is the analysis of the emotional, healthy and physiological effects of this radical routine disruption, in a sample of 3000 Italian people. Methods: We made use of a 5-days flash survey in an anonymous way, available from April the 5th until April the 10th. Results: As expected, results show a healthy decrease, after just one month of lockdown, at several stages: emotional, relational, nutritional and physical. Conclusions: This quarantine period can be considered as an extreme example of immediate sedentary and isolation effects on people. Home habits such as basic physical activity, circadian rhythm routine, proper diet, and correct information consumption can be useful to increase our resilience in difficult times like the current one, but also in our next future.

Antler cycle and thermolabile and thermostable alkaline phosphatase in white-tailed deer; circannual and circadian rhythms and variation after thyroxine, dexamethasone and ACTH administration

1986 ◽  
Vol 111 (1) ◽  
pp. 133-139 ◽  
Author(s):  
A. J. Sempéré ◽  
G. A. Bubenik ◽  
J. H. Smith
Keyword(s):  
Alkaline Phosphatase ◽  
Circadian Rhythm ◽  
Seasonal Variation ◽  
Circadian Rhythms ◽  
Adult Male ◽  
Plasma Levels ◽  
Close Correlation ◽  
The Other ◽  
Low Concentration ◽  
Antler Cycle

Abstract. The plasma levels of thermolabile (TLAP) and thermostable (TSAP) alkaline phosphatase were investigated in adult male white-tailed deer. Distinct seasonal variation of TLAP (with highly elevated levels in July) were observed, whereas TSAP exhibits low concentration with a small increase in October. No circadian rhythm was found for TLAP or TSAP. A close correlation (r = 0.98) between TLAP activity and antler weight was found. Administration of ACTH or dexamethasone were ineffective in influencing AP activity. On the other hand, variations of triiodothyronine (T3) levels in plasma induced by thyroxine (T4) injections correlated well with concentration of TLAP.

Circadian rhythm in intracellular Cl− activity of acutely dissociated neurons of suprachiasmatic nucleus

2002 ◽  
Vol 282 (2) ◽  
pp. C366-C373 ◽  
Author(s):  
Masahiko Shimura ◽  
Norio Akaike ◽  
Nobutoshi Harata
Keyword(s):  
Circadian Rhythm ◽  
Suprachiasmatic Nucleus ◽  
Single Channel ◽  
Reversal Potential ◽  
Circadian Cycle ◽  
Channel Conductance ◽  
Patch Clamp Technique ◽  
Circadian Changes ◽  
Induced Currents ◽  
Perforated Patch Clamp

A link between the circadian rhythm and the function of Cl−-permeable γ-aminobutyric acid (GABA) type A (GABAA) receptors on suprachiasmatic nucleus (SCN) neurons was studied by measuring intracellular activity of Cl−( aCl[Formula: see text]) at different times during a circadian cycle in SCN neurons acutely dissociated from rat brains. To measure aCl[Formula: see text], the voltage-clamp mode of the gramicidin-perforated patch-clamp technique was used, and reversal potential of GABA-induced currents ( E GABA) was converted to aCl[Formula: see text]. Measured aCl[Formula: see text] was significantly higher at around noon (20.1 ± 1.4 mM) than at three other time zones of a circadian cycle (means ranging from 11.6 to 14.3 mM). Chord conductance of GABA-induced currents showed no circadian changes, indicating a lack of circadian changes in the number or single-channel conductance of GABAA receptors. These results suggest that aCl[Formula: see text] participates in modulating GABAA receptor functions on SCN neurons during the circadian rhythm.

scholarly journals Severe underestimation of COVID-19 case numbers: effect of epidemic growth rate and test restrictions

2020 ◽  
Author(s):  
Peter Richterich
Keyword(s):  
Growth Rate ◽  
Rapid Growth ◽  
Quantitative Relation ◽  
Test Results ◽  
Actual Number ◽  
Growth Phases ◽  
Rt Pcr ◽  
Daily Growth ◽  
Testing Strategies ◽  
Testing Policies

AbstractTo understand the scope and development of the COVID-19 pandemic, knowledge of the number of infected persons is essential. Often, the number of “confirmed cases”, which is based on positive RT-PCR test results, is regarded as a reasonable indicator. However, limited COVID-19 test capacities in many countries are restricting the amount of testing that can be done. This can lead to the implementation of testing policies that restrict access to COVID-19 tests, and to testing backlogs and delays. As a result, confirmed case numbers can be significantly lower than the actual number of infections, especially during rapid growth phases of the epidemic.This study examines the quantitative relation between infections and reported confirmed case numbers for two different testing strategies, “limited” and “inclusive” testing, in relation to the growth rate of the epidemic. The results indicate that confirmed case numbers understate the actual number of infections substantially; during rapid growth phases where the daily growth rate can reach or exceed 30%, as has been seen in many countries, the confirmed case numbers under-report actual infections by up to 50 to 100-fold.

scholarly journals Kinetic analysis of the growth rate of sporadic and hereditary medullary thyroid carcinoma: Comparing the postoperative calcitonin-doubling rate with the hypothetical preoperative tumor volume-doubling rate

2020 ◽  
Author(s):  
Minoru Kihara ◽  
Akira Miyauchi ◽  
Hiroo Masuoka ◽  
Takuya Higashiyama ◽  
Yasuhiro Ito ◽  
...  
Keyword(s):  
Thyroid Carcinoma ◽  
Medullary Thyroid Carcinoma ◽  
Rapid Growth ◽  
Tumor Volume ◽  
Papillary Thyroid ◽  
Growth Phases ◽  
Medullary Thyroid ◽  
Age At Surgery ◽  
Hereditary Medullary Thyroid Carcinoma ◽  
Volume Doubling

Abstract Background Our previous kinetic analyses of changes in the tumor volume (TV) of papillary thyroid microcarcinomas during active surveillance revealed that the tumors' growth varied over time from rather rapid growth to shrinkage and that the hypothetical TV-doubling rates (DRs) before the patients' presentation were much larger than their observed TV-DRs, indicating that rapid growth phases preceded their presentation. Whether this phenomenon also occurs in medullary thyroid carcinoma (MTC) was unknown. Methods We retrospectively analyzed the cases of 46 MTC patients (18 hereditary, 28 sporadic; 9–80 years old at surgery, median 53.5 years; 19 males and 27 females) with elevated postoperative calcitonin (Ct) suggesting persistent disease. We calculated each patient's Ct-DR and his/her hypothetical TV-DR, using the tumor size and age at surgery. Results Ct-DRs (/year) after surgery were >0.5, 0.1–0.5, −0.1–0.1, and <������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������

Inhibitors of protein synthesis on 80S ribosomes phase shift the Gonyaulax clock

1982 ◽  
Vol 97 (1) ◽  
pp. 121-136
Author(s):  
W. R. Taylor ◽  
J. C. Dunlap ◽  
J. W. Hastings
Keyword(s):  
Protein Synthesis ◽  
Circadian Rhythm ◽  
Circadian Rhythms ◽  
Phase Shift ◽  
Phase Shifts ◽  
Circadian Cycle ◽  
Response Curves ◽  
80S Ribosome ◽  
Strong Phase ◽  
Additional Support

One-hour pulses of anisomycin (0.3 microM), streptimidone (30 microM) and cycloheximide (5 microM) caused strong phase-shifts (either advances or delays, of up to 12 h) in the circadian rhythm of the bioluminescence glow in the marine photosynthetic dinoflagellate, Gonyaulax polyedra. Similar pulses of emetine (0.1-100 microM) caused small (less than 4 h) phase shifts. Drug pulses have quantitatively different effects when applied at different phases of the circadian cycle, thus giving rise to ‘phase response curves’ (PRC's). The results lend additional support to the generalization, based on results from several different organisms, that 80s ribosome protein synthesizing system is of key importance in the mechanism responsible for circadian rhythms.

In Vivo Chondrogenesis of BMSCs at Non-Chondrogenesis Site by Co-Transplantation of BMSCs and Chondrocytes with Pluronic as Biomaterial

2005 ◽  
Vol 288-289 ◽  
pp. 3-6 ◽  
Author(s):  
Guang Dong Zhou ◽  
Wei Liu ◽  
Lei Cui ◽  
Yi Lin Cao
Keyword(s):  
Stromal Cells ◽  
Bone Marrow Stromal Cells ◽  
Fibrous Tissue ◽  
Cartilage Tissue Engineering ◽  
Cell Number ◽  
Marrow Stromal Cells ◽  
Cartilage Tissue ◽  
Low Concentration ◽  
Wet Weight

Bone Marrow Stromal Cells (BMSCs) have chondrogenesis potential if chondrogenic environments or factors are provided. This study tests the hypothesis that chondrocytes can promote BMSC chondrogenesis at non-chondrogensis site. Porcine BMSCs and auricular chondrocytes were mixed at different ratios and 2.5×107 mixed cells were resuspended in 0.5 ml 30％ Pluronic, and then the mixture was injected into nude mice subcutaneously as experimental groups. Chondrocytes or BMSCs at the same cell number were mixed with 0.5 ml Pluronic and injected respectively as controls. 2.5×107 chondrocytes were mixed and injected as low concentration chondrocyte control. 8 weeks later, all specimens in experimental groups and chondrocyte group formed mature cartilage with abundant collagen II expression. Mature lacuna structures and metachromatic matrices were also observed in these specimens with the same level of GAG contents. Average wet weight of specimens in experimental groups was over 70% of that in chondrocyte group. In contrast, specimens in BMSC group showed mainly fibrous tissue. Only a small amount of cartilage was formed in specimens of low concentration chondrocyte group and the average wet weight was below 30% of that in chondrocyte group. These results demonstrate that chondrocytes can provide chondrogenic microenvironment and thus promote in vivo chondrogenesis of BMSCs at non-chondrogenesis sites. It also indicates that Pluronic is an ideal injectable biomaterial for cartilage tissue engineering.

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