Pineal Enzymes: Regulation of Avian Melatonin Synthesis

Binkley, Sue; Macbride, Steven E.; Klein, David C.; Ralph, Charles L.

doi:10.1126/science.181.4096.273-a

Cited by 137 publications

(58 citation statements)

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“…The rhythm in TPH mRNA levels [14,19,29] is followed by a lowamplitude rhythm of TPH enzyme activity in the retina [38] and of TPH neosynthesis in the pineal gland [18]. HIOMT enzyme activity only shows 20 % changes throughout the light/dark cycle in the chicken pineal gland [7] and no clear-cut day/night changes in the retina (Bernard M [19] [8,16], the next question to ask was whether this pineal oscillator was the one involved in the rhythmic expression of the TPH, AANAT and HIOMT genes. To answer this question, the levels of mRNAs transcribed from these three genes were analyzed in vitro and in constant darkness.…”

Section: Introductionmentioning

confidence: 99%

Melatonin synthesis pathway: circadian regulation of the genes encoding the key enzymes in the chicken pineal gland and retina

Bernard¹,

Guerlotté²,

Grève³

et al. 1999

Reprod. Nutr. Dev.

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-The mRNAs encoding three enzymes of the melatonin synthesis pathway (tryptophan hydroxylase (TPH), arylalkylamine-N-acetyltransferase (AANAT) and hydroxyindole-O-methyltransferase (HIOMT)) are expressed with a day/night rhythm in the chicken pineal gland and retina. TPH and AANAT mRNA levels reach their peak at night. HIOMT mRNA levels peak at night in the retina, but during the day in the pineal gland. In this tissue, the rhythm of TPH, AANAT and HIOMT mRNA levels persisted in constant darkness (DD), both in vivo and in vitro, indicating that the three genes are controlled by the circadian oscillator of the chicken pineal. In the retina, the rhythms of TPH and AANAT mRNA levels also persisted in DD in vivo, suggesting that they are driven by a circadian oscillator. In contrast, the rhythm of HIOMT mRNA in the retina appeared to be controlled only by light. The clones of chicken AANAT and HIOMT genes that we have isolated should help us to understand the molecular mechanisms of: 1) their transcriptional regulation by circadian oscillators and by light; 2) their tissue-specific expression in the pineal gland and the retina. © Inra/ Elsevier,

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Section: Introductionmentioning

confidence: 99%

Melatonin synthesis pathway: circadian regulation of the genes encoding the key enzymes in the chicken pineal gland and retina

Bernard¹,

Guerlotté²,

Grève³

et al. 1999

Reprod. Nutr. Dev.

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“…In fact, transducin immunoreactivity has been observed in chicken pineal (18) and rod, but not cone, transducin ␣ subunit mRNA has been detected in chicken pineal gland. 2 …”

Section: P-opsin Expressed In Cp3 Cellsmentioning

confidence: 99%

“…This protein, pineal opsin (P-opsin), is ϳ40% identical to the visual pigments. P-opsin, but none of the known chicken visual opsins, was found to be expressed in pinealocytes by RNase protection and in situ hybridization, 2 suggesting that P-opsin might mediate pineal phototransduction. A consideration of P-opsin's amino acid sequence suggests that it binds 11-cis-retinal and activates transducin.…”

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Light-dependent Activation of Rod Transducin by Pineal Opsin

Max¹,

Surya²,

Takahashi³

et al. 1998

Journal of Biological Chemistry

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The pineal gland expresses a unique member of the opsin family (P-opsin; Max, M., McKinnon, P. J., Seidenman, K. J., Barrett, R. K., Applebury, M. L., Takahashi, J. S., and Margolskee, R. F. (1995) Science 267, 1502-1506) that may play a role in circadian entrainment and photo-regulation of melatonin synthesis. To study the function of this protein, an epitope-tagged P-opsin was stably expressed in an embryonic chicken pineal cell line. When incubated with 11-cis-retinal, a light-sensitive pigment was formed with a max at 462 ؎ 2 nm. P-opsin bleached slowly in the dark (t 1/2 ‫؍‬ 2 h) in the presence of 50 mM hydroxylamine. Purified P-opsin in dodecyl maltoside activated rod transducin in a light-dependent manner, catalyzing the exchange of more than 300 mol of GTP␥S (guanosine 5-O-(3-thiotriphosphate))/mol of P-opsin. The initial rate for activation (75 mol of GTP␥S bound/mol of P-opsin/min at 7 M) increased with increasing concentrations of transducin. The addition of egg phosphatidylcholine to P-opsin had little effect on the activation kinetics; however, the intrinsic rate of decay in the absence of transducin was accelerated. These results demonstrate that P-opsin is an efficient catalyst for activation of rod transducin and suggest that the pineal gland may contain a rodlike phototransduction cascade.

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“…6) (Ralph et al, 1967 ;Lynch, 1971 ;Binkley et al, 1973 ;Ralph et al, 1974). Les quantités de mélatonine éva-luées dans l'épiphyse du Pigeon par dosage radioimmunologique sont inférieures à celles obtenues chez le Poulet et chez la Caille (Ralph, 1976 (Pelham, 1975 (Quay, 1974 Dans la rétine de Pigeon, l'augmentation de la concentration en mélatonine au cours de la phase nocturne pourrait refléter l'augmentation de l'activité NAT (Hamm et Menaker, 1980), alors que l'activité HIOMT ne semble pas présenter de variations nycthémérales dans la rétine pour la production de mélatonine (Wainwright, 1979 ;Pévet et al, 19801. …”

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Mélatonine dans l'organe pinéal, la rétine et le plasma. Etude immunologique chez le Pigeon

VOISIN¹,

GEFFARD²,

DELAAGE³

et al. 1982

Reprod. Nutr. Dévelop.

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Summary. An immuno%gical study of melatonin in the pineal organ, retina and plasma of the pigeon.Circadian variations in melatonin content have been studied in the pineal organ, retina and plasma of adult pigeons using radioimmunoassay. A clear-cut peak of melatonin was observed in the pineal organ at middark ; this middark peak was of larger amplitude in July than in November. A nocturnal rise in melatonin concentration was also observed in the retina and plasma.We also used an immunocytochemical technique revealing the positive reactions of a melatonin-like compound in the photoreceptor cell layer (inner segments) of the pigeon's retina. Up to now, no melatonin storage has been visualized in the pineal organ of the pigeon.Introduction.

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Pineal Enzymes: Regulation of Avian Melatonin Synthesis

Abstract: The existence of two series of mechanical resonance frequencies in human cancellous bone is apparently supported by other results. This effect may be a microstrain phenomenon since all

Cited by 137 publications

References 31 publications

Melatonin synthesis pathway: circadian regulation of the genes encoding the key enzymes in the chicken pineal gland and retina

Melatonin synthesis pathway: circadian regulation of the genes encoding the key enzymes in the chicken pineal gland and retina

Light-dependent Activation of Rod Transducin by Pineal Opsin

Mélatonine dans l'organe pinéal, la rétine et le plasma. Etude immunologique chez le Pigeon

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