The Quail's Eye: A Biological Clock

Underwood, Herbert; Barrett, R. Keith; Siopes, T. D.

doi:10.1177/074873049000500307

Cited by 97 publications

(54 citation statements)

References 27 publications

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“…These results suggest that extraretinally perceived light does not participate in photic entrainment of ocular melatonin rhythms. In Japanese quail, a light-entrainable circadian clock driving ocular melatonin rhythms has been shown to reside in the eyes [22]. Therefore it is likely that pigeons also have such a circadian clock within the eyes.…”

Section: Phase Control O F Circadian Melatonin Rhythms By Lightmentioning

confidence: 99%

“…In mammals also, localization of ocular circadian oscillators has been shown by in vitro experi ment [23]. Although no in vitro evidence has been available, several lines of in vivo evidence have suggested that circadian oscillators are located in avian retina [22,24]. Because dopa mine is implicated in retinal melatonin synthe sis [10], we measured dopamine and melatonin release in the pigeon's eye in order to under stand circadian mechanisms of retinal mela tonin rhythms.…”

Section: Circadian Mechanisms Of Retinal Melatonin Rhythmsmentioning

confidence: 99%

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In vivo Microdialysis Studies of Pineal and Ocular Melatonin Rhythms in Birds

et al. 1997

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Pineal and retinal melatonin has an important role in the control of avian circadian rhythms. In order to study the mechanisms of circadian rhythms of melatonin synthesis in the pineal and in the eye, in vivo microdialysis was applied to these organs. In both pigeons and Japanese quails, pineal and ocular melatonin levels were high during the dark and low during the day under light-dark (LD) cycles. These rhythms persisted under constant dim light (LLdim) conditions indicating the circadian nature of pineal and ocular melatonin release. Light has two effects on melatonin synthesis. One is acute inhibition of melatonin synthesis and the other is entrainment of circadian melatonin rhythms. We have examined photoreceptors mediating these effects in the pigeon. The results have indicated that the eyes are not involved in light-induced suppression and photic entrainment of pineal melatonin release, and pineal photoreceptors themselves are likely to mediate these effects. Concerning ocular melatonin, retinal photoreceptors seem to mediate light-induced suppression and photic entrainment and no evidence supporting mediation of extraretinal photoreceptors was obtained. Because dopamine is implicated in retinal melatonin synthesis, we measured dopamine and melatonin release simultaneously from the eye of pigeon. In contrast to melatonin rhythms, dopamine increased during the day and decreased during the dark. This antiphase relationship between melatonin and dopamine persisted in LLdim, suggesting an interaction between these two rhythms. The results of an intraocular injection of dopamine or melatonin in the phase of melatonin and dopamine rhythms indicated that the interaction is required for maintaining the antiphase relationship between the two rhythms.

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Section: Phase Control O F Circadian Melatonin Rhythms By Lightmentioning

confidence: 99%

Section: Circadian Mechanisms Of Retinal Melatonin Rhythmsmentioning

confidence: 99%

In vivo Microdialysis Studies of Pineal and Ocular Melatonin Rhythms in Birds

et al. 1997

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“…The presence of another circadian oscillator in the hypothalamus is suggested by the fact that lesions which include the SCN also make birds arrhythmic (15). Although there is no published work on retinal rhythmicity in passerines, the retinas of some other birds (chickens, quail and pigeons) appear to synthesize melatonin rhythmically and probably contain circadian oscillators (16).…”

mentioning

confidence: 99%

Evolution of circadian organization in vertebrates

Menaker¹,

Moreira²,

Tosini³

1997

Braz J Med Biol Res

144

104

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Circadian organization means the way in which the entire circadian system above the cellular level is put together physically and the principles and rules that determine the interactions among its component parts which produce overt rhythms of physiology and behavior. Understanding this organization and its evolution is of practical importance as well as of basic interest. The first major problem that we face is the difficulty of making sense of the apparently great diversity that we observe in circadian organization of diverse vertebrates. Some of this diversity falls neatly into place along phylogenetic lines leading to firm generalizations: i) in all vertebrates there is a "circadian axis" consisting of the retinas, the pineal gland and the suprachiasmatic nucleus (SCN), ii) in many non-mammalian vertebrates of all classes (but not in any mammals) the pineal gland is both a photoreceptor and a circadian oscillator, and iii) in all non-mammalian vertebrates (but not in any mammals) there are extraretinal (and extrapineal) circadian photoreceptors. An interesting explanation of some of these facts, especially the differences between mammals and other vertebrates, can be constructed on the assumption that early in their evolution mammals passed through a "nocturnal bottleneck". On the other hand, a good deal of the diversity among the circadian systems of vertebrates does not fall neatly into place along phylogenetic lines. In the present review we will consider how we might better understand such "phylogenetically incoherent" diversity and what sorts of new information may help to further our understanding of the evolution of circadian organization in vertebrates. Key wordsOrganisms, from unicellulars to vertebrates, are structured in time as well as in space. Many, if not most, biochemical, physiological and behavioral parameters exhibited by organisms show daily fluctuations and most of these daily rhythms persist in constant conditions, thus demonstrating that they are driven by endogenous oscillators. The rhythms that persist in constant conditions with periods close to 24 h are called circadian rhythms.By circadian organization we mean the way in which the entire circadian system above the cellular level is put together physically, and the principles and rules that determine the interactions among its component parts. Circadian organization extends both broadly and deeply into the physiology and

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“…A similar circadian regulation of melato nin production by local circadian oscillators (probably located in photoreceptor cells) has been reported in the retina of the hamster, Japanese quail, African clawed frog and zebrafish [7,[12][13][14][15]. Taken together, these re sults indicate, at least in some vertebrate spe cies including fish, that the retina harbors a circadian clock regulating melatonin rhythms and may play an important role in the circa dian organization.…”

Section: Melatonin Rhythms In Fishesmentioning

confidence: 51%

Photic and Circadian Regulations of Melatonin Rhythms in Fishes

Iigo

Hara²,

Ohtani-Kaneko³

et al. 1997

Neurosignals

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Photic and circadian regulations of melatonin rhythms in the pineal organ and the retina of several teleosts were studied to investigate the regulatory mechanisms of melatonin rhythms in fishes. In the eyecup preparations of the goldfish, Carassius auratus, both time of day and lighting conditions affected melatonin production, with high melatonin production observed only in the dark-treated group incubated during the ‘subjective’ night. Thus, in the goldfish retina, local photoreceptors and an ocular circadian clock seem to regulate melatonin production, as in the zebrafish retina and in the pineal organ of a number of teleosts, including the goldfish. However, this circadian regulation of melatonin rhythms is not universal among fishes. Although the superfused pineal organ of the masu salmon Oncorhynchus masou secreted melatonin in a rhythmic fashion under light-dark (LD) cycles, the rhythm disappeared under constant darkness (DD), as in the rainbow trout, with a large amount of melatonin released both during the subjective day and the subjective night. These results suggest that all salmonids lack circadian regulation of melatonin rhythms. Furthermore, when ocular melatonin rhythms were compared in two cyprinids, the ugui Tribolodon hakonensis and the oikawa Zacco platypus occupying different ecological niches, ocular melatonin contents exhibited daily variations, with higher values during the dark phase of LD cycles in both species. The rhythmic changes persisted in the ugui under DD, with higher levels at subjective midnight than at subjective midday; however, ocular melatonin levels in the oikawa were consistently high under DD. Thus, the circadian regulation of melatonin rhythms in fishes is influenced not only by phylogeny, but also by the ecological niches of the animals. These results suggest that the physiological functions of melatonin in the circadian and photoperiodic systems differ among fishes.

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The Quail's Eye: A Biological Clock

Cited by 97 publications

References 27 publications

In vivo Microdialysis Studies of Pineal and Ocular Melatonin Rhythms in Birds

In vivo Microdialysis Studies of Pineal and Ocular Melatonin Rhythms in Birds

Evolution of circadian organization in vertebrates

Photic and Circadian Regulations of Melatonin Rhythms in Fishes

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