scholarly journals Transcriptional regulation of hydroxyindole O-methyltransferase in the chicken pineal gland: day/night changes and long-term effects of light and darkness

1993 ◽  
Vol 290 (3) ◽  
pp. 661-664 ◽  
Author(s):  
M Bernard ◽  
J Guerlotte ◽  
M Cogne ◽  
P Greve ◽  
J P Collin ◽  
...  
Keyword(s):  
Pineal Gland ◽  
Gene Transcription ◽  
Cdna Probe ◽  
Constant Light ◽  
Constant Darkness ◽  
Mrna Levels ◽  
Long Term Effects ◽  
Night Time ◽  
Environmental Lighting ◽  
Time Fall

The indolic hormone melatonin is produced by the pineal gland according to a daily rhythm. The terminal step of melatonin synthesis is catalysed by hydroxyindole O-methyltransferase (HIOMT, EC 2.1.1.4). Adaptation to constant light or darkness modifies HIOMT activity and concentration. Using a cDNA probe encoding HIOMT, we investigated the effect of environmental lighting on HIOMT gene expression in the chicken pineal gland. HIOMT mRNA levels increased by 100% in constant light as compared with constant darkness. In addition, the present study disclosed the existence of a day/night rhythm of HIOMT gene transcription, with 3-fold higher mRNA levels at midday than at midnight. This transcriptional rhythm was not accompanied by day/night changes in HIOMT concentration, probably due to a slow turnover of this protein. Unexpected darkness did not prevent the daytime rise in HIOMT mRNA levels, whereas unexpected light prevented the night-time fall in HIOMT mRNA levels. Together, the data would suggest that the day/night rhythm of HIOMT gene transcription in the chicken pineal gland involves both a response to light and the activity of a biological oscillator.

Effects of Changes in Environmental Lighting Upon Levels of Hydroxyindole O-Methyltransferase Activity in the Developing-Chick Pineal Gland

1975 ◽  
Vol 53 (4) ◽  
pp. 438-443 ◽  
Author(s):  
S. D. Wainwright
Keyword(s):  
Enzyme Activity ◽  
Pineal Gland ◽  
Diurnal Cycle ◽  
Enzymic Activity ◽  
Constant Light ◽  
Constant Darkness ◽  
Methyltransferase Activity ◽  
Constant Illumination ◽  
Lighting Conditions ◽  
Environmental Lighting

The level of hydroxyindole O-methyltransferase (HIOMT) activity in the pineal gland of developing chicks raised under constant illumination rose more rapidly and to higher values than in the gland of birds maintained in constant darkness. Rates of net increase in activity, and levels of activity attained, for birds raised under a diurnal cycle of illumination were intermediate between those maintained in constant light or darkness. Under each of the lighting conditions, the course of increase in enzymic activity was markedly affected by variations in an unidentified factor, the source of which appeared to be the hatching eggs.Birds transferred from constant light to the dark showed either an arrest of increase in enzyme activity or a loss of activity until the level equalled that observed for chicks of the same age raised in constant darkness. Chicks transferred from constant darkness to constant illumination showed marked increases in levels of enzyme activity at rates comparable with the maximal values observed with birds maintained under constant illumination, regardless of age and without delay. No diurnal cycle in level of HIOMT activity was observed in the pineals of 15-day birds.

Impact of photoperiodic exposures during late gestation and lactation periods on the pineal and reproductive physiology of the Indian palm squirrel, Funambulus pennanti

Reproduction ◽  
2000 ◽  
pp. 295-301 ◽  
Author(s):  
KS Bishnupuri ◽  
C Haldar
Keyword(s):  
Pineal Gland ◽  
Recovery Process ◽  
Reproductive Physiology ◽  
Late Gestation ◽  
Constant Light ◽  
Constant Darkness ◽  
Lactation Period ◽  
Postpartum Recovery ◽  
The Impact ◽  
Constant Dark

Studies on the maternal transfer of photoperiodic information in mammals indicate that the daily photoperiod perceived by the mother during the gestation-lactation period is communicated to the fetus either through the placenta or via the milk. However, the impact of photoperiodic exposures during gestation and lactation on the maternal pineal and reproductive physiology has not been reported for any tropical rodent. The exposure of pregnant female Indian palm squirrels (Funambulus pennanti) to constant light (24 h light:0 h dark), constant dark (0 h light:24 h dark), long daylength (14 h light:10 h dark) or short daylength (10 h light:14 h dark) during early gestation (< 30 days) resulted in the resorption of pregnancy, while during late gestation (> 30 days), it did not interfere with the maintenance of pregnancy. Alterations in photoperiodic condition during late gestation and lactation altered the postpartum recovery process. Pineal gland activity, as assessed by pineal mass, protein content and plasma melatonin, was lowest during the breeding phase, but increased gradually after parturition until the next breeding phase. During gestation and lactation, constant light, long daylength and short daylength conditions were less effective, while constant dark condition had a profound effect in depressing pineal gland activity, which subsequently advanced postpartum recovery. Hence, lactating females under constant darkness prepare themselves for next mating much earlier than females under natural daylength (12 h light:12 h dark) conditions. Therefore, photoperiodic information, mediated via the pineal gland, may be important for maintaining gestation physiology as well as postpartum recovery in female rodents.

scholarly journals Circadian regulation of hydroxyindole-O-methyltransferase mRNA in the chicken pineal gland in vivo and in vitro

1996 ◽  
Vol 319 (3) ◽  
pp. 761-766 ◽  
Author(s):  
Pierre GRÈVE ◽  
Pierre VOISIN ◽  
Aline GRECHEZ-CASSIAU ◽  
Marianne BERNARD ◽  
Jean-Pierre COLLIN ◽  
...  
Keyword(s):  
Pineal Gland ◽  
Constant Darkness ◽  
Dark Phase ◽  
Mrna Levels ◽  
Circadian Oscillators ◽  
The Stability ◽  
Daily Changes ◽  
Effect Of Light

The production of the pineal hormone melatonin displays circadian variations with high levels at night. The last enzyme involved in melatonin biosynthesis is hydroxyindole-O-methyltransferase (HIOMT, EC 2.1.1.4). The expression of the mRNA encoding chicken HIOMT was investigated in vivo and in vitro throughout the light/dark cycle, in constant darkness and with light interruption of the dark phase. The stability of HIOMT mRNA was also examined. A day/night rhythm of HIOMT mRNA levels, with a peak at the midlight phase, was observed in vivo as well as in vitro. Constant darkness did not abolish this rhythm in vivo. One cycle of the HIOMT mRNA rhythm could be observed in constant darkness in vitro. In addition, a stimulatory effect of light on HIOMT mRNA levels during the dark phase could be observed in vivo as well as in vitro. HIOMT mRNA stability was not affected by light or dark conditions, as demonstrated by chase experiments with actinomycin D. The results indicate that the daily changes in HIOMT mRNA concentration reflect transcriptional regulation by circadian oscillators and photosensory mechanisms that are endogenous to the pineal gland.

Patterns of progesterone, melatonin and prolactin secretion in ewes maintained in four different photoperiods

1983 ◽  
Vol 97 (2) ◽  
pp. 229-242 ◽  
Author(s):  
D. J. Kennaway ◽  
L. M. Sanford ◽  
B. Godfrey ◽  
H. G. Friesen
Keyword(s):  
Pineal Gland ◽  
Endocrine System ◽  
Prolactin Secretion ◽  
Constant Light ◽  
Ovarian Activity ◽  
Dark Phase ◽  
Melatonin Secretion ◽  
Night Time ◽  
Serum Progesterone ◽  
Natural Photoperiod

Twenty-four-hour patterns of serum melatonin and prolactin levels were determined in ewes on nine occasions during a year. The sheep were maintained in four different photoperiods: room 1, simulated natural photoperiod; room 2, normal daylength extremes twice in 12 months, changes occurring in a regular fashion; room 3, alternating long (16 h) and short (8 h) days for 90 days; room 4, constant light. Cyclic ovarian activity, determined by twice-weekly determinations of serum progesterone, commenced in rooms 1, 2 and 3 after a transition from long to short daylength and terminated during long daylength. Thus in rooms 2 and 3 there were two periods of ovarian activity. In room 4 (constant light) ovarian activity began earlier than in room 1 and was of greater duration (240 days v. 190 days). Basal prolactin levels were highest (50–134 μg/l) during periods of long daylength and lowest (< 10 μ/l) in short daylength. Ewes maintained in constant light had an intermediate level (21–62 μg/l) throughout the study. Melatonin secretion was lowest during daylight (< 78 pmol/l) and highest during darkness. Night-time melatonin levels varied markedly from hour to hour and between individuals in rooms 1, 2 and 3. There was, however, no consistent seasonal change in the absolute levels of melatonin, although the duration of melatonin secretion did closely follow the length of the dark phase. There were no significant changes in melatonin levels during the oestrous cycle. Ewes kept in constant light had < 78 pmol melatonin/l throughout the period of study. If the pineal gland is involved in transmitting photoperiodic information to the endocrine system, then it is most likely to be by means of an interaction between duration of melatonin secretion and an underlying change in sensitivity of end organs to melatonin.

EFFECTS OF SEX HORMONES AND ENVIRONMENTAL LIGHTING ON RAT HARDERIAN GLAND PORPHYRIN

1974 ◽  
Vol 63 (1) ◽  
pp. 99-102 ◽  
Author(s):  
RENÉE ULRICH ◽  
ARTHUR YUWILER ◽  
EDWARD GELLER ◽  
LENNART WETTERBERG
Keyword(s):  
Harderian Gland ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Constant Light ◽  
Constant Darkness ◽  
Intact Control ◽  
Gland Weight ◽  
Lighting Conditions ◽  
Harderian Glands ◽  
Environmental Lighting

SUMMARY Ovariectomy of adult female rats significantly decreased the porphyrin content of the Harderian glands compared with intact control rats. Treatment of ovariectomized rats for 5 days with testosterone propionate, progesterone or oestradiol did not alter porphyrin content or concentration; however, administration of oestradiol plus progesterone significantly increased Harderian gland porphyrin content to values indistinguishable from those of intact controls. Additionally, oestradiol treatment lowered the weight of the Harderian glands. Constant light or constant darkness for 35 days significantly decreased Harderian gland porphyrins compared with those of rats kept in diurnal lighting conditions. Constant light significantly lowered porphyrin values compared with those obtained from rats maintained in constant darkness. The effects of constant light were not altered by either ovariectomy or enucleation. Harderian gland weight was reduced in all groups kept in constant light.

Night-time disability glare of constant-light LED traffic monitoring fill light

2021 ◽  
pp. 147715352098226
Author(s):  
X Cai ◽  
L Quan ◽  
J Wu ◽  
Y He
Keyword(s):  
Dynamic Range ◽  
Road Traffic ◽  
Reaction Times ◽  
High Dynamic Range ◽  
Luminance Contrast ◽  
Traffic Monitoring ◽  
Constant Light ◽  
Night Time ◽  
Disability Glare ◽  
Small Targets

Fill light, used to helps cameras capture road traffic conditions at night, can lead to serious visual consequences for drivers. Research on disability glare from LED fill light is scarce and therefore this study explored strategies for controlling disability glare of constant-light LED traffic monitoring fill light. The threshold increment was used as an index to evaluate disability glare. The effective disability glare area of LED traffic monitoring fill light was determined based on high dynamic range technology. According to visual efficacy theory, there is a relationship between disability glare conditions and reaction times. The influencing factors include background luminance, luminance contrast and fill light luminance. The results showed that disability glare was the most intense in a range of 20 m to 30 m in front of LED fill light. To reduce the effect of disability glare on drivers, luminance contrast between small targets and the road surface should be greater than 0.5. The fill light luminance should not be greater than 100,000 cd/m2.

Nitric oxide increases IL-8 gene transcription and mRNA stability to enhance IL-8 gene expression in lung epithelial cells

2004 ◽  
Vol 287 (4) ◽  
pp. L764-L773 ◽  
Author(s):  
Loretta Sparkman ◽  
Vijayakumar Boggaram
Keyword(s):  
Gene Expression ◽  
Nitric Oxide ◽  
Protein Kinase ◽  
Epithelial Cells ◽  
Gene Transcription ◽  
Mrna Stability ◽  
Inflammatory Responses ◽  
Lung Epithelial Cells ◽  
Mrna Levels ◽  
Lung Epithelial

Interleukin (IL)-8, a C-X-C chemokine, is a potent chemoattractant and an activator for neutrophils, T cells, and other immune cells. The airway and respiratory epithelia play important roles in the initiation and modulation of inflammatory responses via production of cytokines and surfactant. The association between elevated levels of nitric oxide (NO) and IL-8 in acute lung injury associated with sepsis, acute respiratory distress syndrome, respiratory syncytial virus infection in infants, and other inflammatory diseases suggested that NO may play important roles in the control of IL-8 gene expression in the lung. We investigated the role of NO in the control of IL-8 gene expression in H441 lung epithelial cells. We found that a variety of NO donors significantly induced IL-8 mRNA levels, and the increase in IL-8 mRNA was associated with an increase in IL-8 protein. NO induction of IL-8 mRNA was due to increases in IL-8 gene transcription and mRNA stability. NO induction of IL-8 mRNA levels was not inhibited by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one and KT-5823, inhibitors of soluble guanylate cyclase and protein kinase G, respectively, and 8-bromo-cGMP did not increase IL-8 mRNA levels. This indicated that NO induces IL-8 mRNA levels independently of changes in the intracellular cGMP levels. NO induction of IL-8 mRNA was significantly reduced by inhibitors of extracellular regulated kinase and protein kinase C. IL-8 induction by NO was also reduced by hydroxyl radical scavengers such as dimethyl sulfoxide and dimethylthiourea, indicating the involvement of hydroxyl radicals in the induction process. NO induction of IL-8 gene expression could be a significant contributing factor in the initiation and induction of inflammatory response in the respiratory epithelium.

The Corfu δβ thalassemia deletion disrupts γ-globin gene silencing and reveals post-transcriptional regulation of HbF expression

Blood ◽  
2005 ◽  
Vol 105 (5) ◽  
pp. 2154-2160 ◽  
Author(s):  
Lyubomira Chakalova ◽  
Cameron S. Osborne ◽  
Yan-Feng Dai ◽  
Beatriz Goyenechea ◽  
Anna Metaxotou-Mavromati ◽  
...  
Keyword(s):  
Transcriptional Regulation ◽  
Gene Transcription ◽  
Globin Gene ◽  
Fetal Hemoglobin ◽  
Critical Threshold ◽  
Critical Element ◽  
Mrna Levels ◽  
Globin Genes ◽  
Mrna Accumulation ◽  
Post Transcriptional Regulation

Abstract The 7.2 kilobase (kb) Corfu δβ thalassemia mutation is the smallest known deletion encompassing a region upstream of the human δ gene that has been suggested to account for the vastly different phenotypes in hereditary persistence of fetal hemoglobin (HPFH) versus β thalassemia. Fetal hemoglobin (HbF) expression in Corfu heterozygotes and homozygotes is paradoxically dissimilar, suggesting conflicting theories as to the function of the region on globin gene regulation. Here, we measure γ- and β-globin gene transcription, steady-state mRNA, and hemoglobin expression levels in primary erythroid cells cultured from several patients with Corfu δβ thalassemia. We show through RNA fluorescence in situ hybridization that the Corfu deletion results in high-level transcription of the fetal γ genes in cis with a concomitant reduction in transcription of the downstream β gene. Surprisingly, we find that elevated γ gene transcription does not always result in a corresponding accumulation of γ mRNA or fetal hemoglobin, indicating a post-transcriptional regulation of γ gene expression. The data suggest that efficient γ mRNA accumulation and HbF expression are blocked until β mRNA levels fall below a critical threshold. These results explain the Corfu paradox and show that the deleted region harbors a critical element that functions in the developmentally regulated transcription of the β-globin genes.

scholarly journals Feedback Inhibition of Human Scavenger Receptor Class B Type I Gene Expression by Glucocorticoid in Adrenal and Ovarian Cells

Endocrinology ◽  
2010 ◽  
Vol 151 (7) ◽  
pp. 3214-3224 ◽  
Author(s):  
Sofia Mavridou ◽  
Maria Venihaki ◽  
Olga Rassouli ◽  
Christos Tsatsanis ◽  
Dimitris Kardassis
Keyword(s):  
Gene Expression ◽  
Gene Transcription ◽  
Feedback Inhibition ◽  
Steroid Hormone ◽  
Scavenger Receptor ◽  
Type I ◽  
Mrna Levels ◽  
Ovarian Cells ◽  
Scavenger Receptor Class ◽  
Class B

Scavenger receptor class B type I (SR-BI) facilitates the reverse transport of excess cholesterol from peripheral tissues to the liver via high-density lipoproteins. In steroidogenic tissues, SR-BI supplies cholesterol for steroid hormone production. We show here that the transcription of the human SR-BI gene is subject to feedback inhibition by glucocorticoid in adrenal and ovarian cells. SR-BI mRNA levels were increased in adrenals from corticosterone-insufficient Crh−/− mice, whereas corticosterone replacement by oral administration inhibited SR-BI gene expression in these mice. SR-BI mRNA levels were increased in adrenals from wild-type mice treated with metyrapone, a drug that blocks corticosterone synthesis. Experiments in adrenocortical H295R and ovarian SKOV-3 cells using cycloheximide and siRNA-mediated gene silencing revealed that glucocorticoid-mediated inhibition of SR-BI gene transcription requires de novo protein synthesis and the glucocorticoid receptor (GR). No direct binding of GR to the SR-BI promoter could be demonstrated in vitro and in vivo, suggesting an indirect mechanism of repression of SR-BI gene transcription by GR in adrenal cells. Deletion analysis established that the region of the human SR-BI promoter between nucleotides −201 and −62 is sufficient to mediate repression by glucocorticoid. This region contains putative binding sites for transcriptional repressors that could play a role in SR-BI gene regulation in response to glucocorticoid. In summary, this is the first report showing that glucocorticoid suppress SR-BI expression suggesting that steroidogenic tissues maintain steroid hormone homeostasis by prohibiting SR-BI-mediated high-density lipoprotein cholesterol uptake when the endogenous levels of glucocorticoid are elevated.

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