Decoding photoperiodic time through
            <i>Per1</i>
            and ICER gene amplitude

Messager, Sophie; Ross, Alexander; Barrett, Perry; Morgan, Peter J.

doi:10.1073/pnas.96.17.9938

Cited by 178 publications

(198 citation statements)

References 28 publications

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“…In the fetus, the SCN depends on transplacental maternal signals for entrainment to the environmental light͞ dark cycle (3), and efferent communication between the SCN and peripheral tissues is not established. The maternal melatonin signal acts to synchronize the fetal SCN (3), and, in adult mammals, it has been demonstrated that melatonin drives rhythmic clock gene expression in the PT (26,33,44). Based on these findings, a plausible hypothesis is that the maternal melatonin signal serves to synchronize both central (SCN) and peripheral components of the fetal circadian system.…”

Section: Discussionmentioning

confidence: 99%

“…Riboprobes were transcribed from cDNA by using T7 RNA polymerase in the presence of 35 S-UTP. Hybridization, posthybridization washes and film autoradiography, and densitometric analyses (performed ''blind'' to animal identity) were carried out as described (26). Selected sections were coated with Ilford K5 liquid emulsion (diluted 1:1 with water) and exposed for 2-4 weeks.…”

Section: Methodsmentioning

confidence: 99%

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Gonadotrophin-releasing hormone drives melatonin receptor down-regulation in the developing pituitary gland

Johnston

Messager

Ebling

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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Melatonin is produced nocturnally by the pineal gland and is a neurochemical representation of time. It regulates neuroendocrine target tissues through G-protein-coupled receptors, of which MT1 is the predominant subtype. These receptors are transiently expressed in several fetal and neonatal tissues, suggesting distinct roles for melatonin in development and that specific developmental cues define time windows for melatonin sensitivity. We have investigated MT 1 gene expression in the rat pituitary gland. MT1 mRNA is confined to the pars tuberalis region of the adult pituitary, but in neonates extends into the ventral pars distalis and colocalizes with luteinizing hormone ␤-subunit (LH␤) expression. This accounts for the well documented transient sensitivity of rat gonadotrophs to melatonin in the neonatal period. Analysis of an upstream fragment of the rat MT 1 gene revealed multiple putative response elements for the transcription factor pituitary homeobox-1 (Pitx-1), which is expressed in the anterior pituitary from Rathke's pouch formation. A Pitx-1 expression vector potently stimulated expression of both MT 1-luciferase and LH␤-luciferase reporter constructs in COS-7 cells. Interestingly, transcription factors that synergize with Pitx-1 to trans-activate gonadotroph-associated genes did not potentiate Pitx-1-induced MT 1-luciferase activity. Moreover, the transcription factor, early growth response factor-1, which is induced by gonadotrophinreleasing hormone (GnRH) and trans-activates LH␤ expression, attenuated Pitx-1-induced MT 1-luciferase activity. Finally, pituitary MT 1 gene expression was 4-fold higher in hypogonadal (hpg) mice, which do not synthesize GnRH, than in their wild-type littermates. These data suggest that establishment of a mature hypothalamic GnRH input drives the postnatal decline in pituitary MT 1 gene expression.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Gonadotrophin-releasing hormone drives melatonin receptor down-regulation in the developing pituitary gland

Johnston

Messager

Ebling

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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“…Peaks of Per1 and Per2 mRNA in the early photophase appear phase-locked to the suppression of melatonin secretion by light onset at dawn. Acute melatonin administration inhibits Per1 mRNA expression while chronic treatments appear to sensitize it to some other stimulatory factor in the PT (Morgan et al 1998;Messager et al 1999Messager et al , 2000von Gall et al 2002). In contrast, melatonin stimulates Cryptochrome 1 (Cry1) mRNA expression (Dardente et al 2003;Johnston et al 2006), and peaks of Cry1 and Cry2 mRNA in the early scotophase appear phase locked to the activation of melatonin synthesis by light offset at dusk.…”

Section: On the Location Of Interval Timers And Circannual Clocksmentioning

confidence: 99%

Tracking the seasons: the internal calendars of vertebrates

Paul

Zucker

Schwartz

2007

Phil. Trans. R. Soc. B

175

152

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Animals have evolved many season-specific behavioural and physiological adaptations that allow them to both cope with and exploit the cyclic annual environment. Two classes of endogenous annual timekeeping mechanisms enable animals to track, anticipate and prepare for the seasons: a timer that measures an interval of several months and a clock that oscillates with a period of approximately a year. Here, we discuss the basic properties and biological substrates of these timekeeping mechanisms, as well as their reliance on, and encoding of environmental cues to accurately time seasonal events. While the separate classification of interval timers and circannual clocks has elucidated important differences in their underlying properties, comparative physiological investigations, especially those regarding seasonal prolactin secretions, hint at the possibility of common substrates.Keywords: seasonality; photoperiodism; circannual; interval timers While the Earth remaineth, seedtime and harvest, and cold and heat, and summer and winter, and day and night shall not cease.Genesis 8: 22, King James Version (1611) As the Earth makes its yearly orbit around the Sun, the planet's 23.58 axial tilt leads to the cyclical environmental changes that we call the seasons. Recurrent challenges to the survival of organisms and their offspring arise with the dawning of each new season, and animals have evolved seasonally induced changes in phenotype that adapt them to these predictable events. For example, in many temperate environments, winter is generally characterized by severe decreases in ambient temperature and food availability, leading to increased energetic demands at a time when resources are diminished. Because energy requirements of female mammals typically increase markedly during lactation (Bronson 1989) and newly weaned offspring are particularly vulnerable to environmental perturbations (Hill 1992), raising offspring during this time of year is often futile. Thus, many temperate species have evolved winter-specific behaviours and physiology to conserve energy (e.g. hibernation, a more insulative pelage, huddling) or provide for escape (e.g. migration). Many species also increase the chances of offspring survival by timing their mating behaviours so that parturition occurs during energetically favourable times of year.

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“…The riboprobe template used for generating a probe for Per1 expression was prepared as described (11). Probes for Per2, Cry1, Cry2, Clock, Bmal1, and CK1 were prepared by RT-PCR from RNA extracted from ovine PT, followed by cloning in pGEM-Teasy (Promega), by using the manufacturer's protocols.…”

Section: Methodsmentioning

confidence: 99%

“…Per1 expression in the PT is photoperiod-responsive (11,12), but, in contrast to the SCN, the most obvious effect of photoperiod on Per1 expression in the PT is on amplitude of expression in the early light phase-with levels 2-to 4-fold higher under long days (11,12). This has led to the hypothesis that the duration of melatonin is decoded in the pattern of clock gene expression in melatonin-responsive tissues.…”

mentioning

confidence: 99%

Temporal expression of seven clock genes in the suprachiasmatic nucleus and the pars tuberalis of the sheep: Evidence for an internal coincidence timer

Lincoln

Messager²,

Andersson³

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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217

205

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The 24-h expression of seven clock genes (Bmal1, Clock, Per1, Per2, Cry1, Cry2, and CK1 ) was assayed by in situ hybridization in the suprachiasmatic nucleus (SCN) and the pars tuberalis (PT) of the pituitary gland, collected every 4 h throughout 24 h, from female Soay sheep kept under long (16-h light͞8-h dark) or short (8-h light͞16-h dark) photoperiods. Locomotor activity was diurnal, inversely related to melatonin secretion, and prolactin levels were increased under long days. All clock genes were expressed in the ovine SCN and PT. In the SCN, there was a 24-h rhythm in Clock expression, in parallel with Bmal1, in antiphase with cycles in Per1 and Per2; there was low-amplitude oscillation of Cry1 and Cry2. The waveform of only Per1 and Per2 expression was affected by photoperiod, with extended elevated expression under long days. In the PT, the high-amplitude 24-h cycles in the expression of Bmal1, Clock, Per1, Per2, Cry1, and Cry2, but not CK1 , were influenced by photoperiod. Per1 and Per2 peaked during the day, whereas Cry1 and Cry2 peaked early in the night. Hence, photoperiod via melatonin had a marked effect on the phase relationship between Per͞Cry genes in the PT. This supports the conclusion that an ''external coincidence model'' best explains the way photoperiod affects the waveform of clock gene expression in the SCN, the central pacemaker, whereas an ''internal coincidence model'' best explains the way melatonin affects the phasing of clock gene expression in the PT to mediate the photoperiodic control of a summer or winter physiology.

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Decoding photoperiodic time through Per1 and ICER gene amplitude

Cited by 178 publications

References 28 publications

Gonadotrophin-releasing hormone drives melatonin receptor down-regulation in the developing pituitary gland

Gonadotrophin-releasing hormone drives melatonin receptor down-regulation in the developing pituitary gland

Tracking the seasons: the internal calendars of vertebrates

Temporal expression of seven clock genes in the suprachiasmatic nucleus and the pars tuberalis of the sheep: Evidence for an internal coincidence timer

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