Neuronal Organization of Deep Brain Opsin Photoreceptors in Adult Teleosts

Hang, Chong Yee; Kitahashi, Takashi; Parhar, Ishwar S.

doi:10.3389/fnana.2016.00048

Cited by 21 publications

(15 citation statements)

References 81 publications

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“…However, in the same study, the authors demonstrated that not all brain nuclei are photosensitive, raising the possibility that even in zebrafish, the different oscillators are not as independently entrained by light as initially thought (Moore & Whitmore 2014). A widespread photosensitive ability may not be a rule in other teleosts as, to date, the existence of photoreceptors has been demonstrated in the pineal gland, retina and deep brain photoreceptors (Menaker et al 1997, Davies et al 2015, Hang et al 2016; blue in Fig. 1), but not in peripheral tissues, although their existence cannot be ruled out (Davies et al 2015).…”

Section: :3mentioning

confidence: 94%

Interplay between the endocrine and circadian systems in fishes

Isorna

Pedro

Valenciano

et al. 2017

Journal of Endocrinology

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The circadian system is responsible for the temporal organisation of physiological functions which, in part, involves daily cycles of hormonal activity. In this review, we analyse the interplay between the circadian and endocrine systems in fishes. We first describe the current model of fish circadian system organisation and the basis of the molecular clockwork that enables different tissues to act as internal pacemakers. This system consists of a net of central and peripherally located oscillators and can be synchronised by the light-darkness and feeding-fasting cycles. We then focus on two central neuroendocrine transducers (melatonin and orexin) and three peripheral hormones (leptin, ghrelin and cortisol), which are involved in the synchronisation of the circadian system in mammals and/or energy status signalling. We review the role of each of these as overt rhythms (i.e. outputs of the circadian system) and, for the first time, as key internal temporal messengers that act as inputs for other endogenous oscillators. Based on acute changes in clock gene expression, we describe the currently accepted model of endogenous oscillator entrainment by the light-darkness cycle and propose a new model for non-photic (endocrine) entrainment, highlighting the importance of the bidirectional cross-talking between the endocrine and circadian systems in fishes. The flexibility of the fish circadian system combined with the absence of a master clock makes these vertebrates a very attractive model for studying communication among oscillators to drive functionally coordinated outputs.

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Section: :3mentioning

confidence: 94%

Interplay between the endocrine and circadian systems in fishes

Isorna

Pedro

Valenciano

et al. 2017

Journal of Endocrinology

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“…Other circadian cellular photopigments are the so-called deep brain photoreceptors (different nonvisual opsins) of non-mammalian vertebrates (Davies et al 2015;Hang et al 2016). In mammals, functional deep brain opsins have so far not been identified, but melanopsin in a subset of the retinal ganglion cells fulfils the role as circadian cellular photopigment (Provencio et al 1998;Berson et al 2002;Hattar et al 2002;reviewed in Lazzerini Ospri et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Light input pathways to the circadian clock of insects with an emphasis on the fruit fly Drosophila melanogaster

Helfrich‐Förster

2019

J Comp Physiol A

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Light is the most important Zeitgeber for entraining animal activity rhythms to the 24-h day. In all animals, the eyes are the main visual organs that are not only responsible for motion and colour (image) vision, but also transfer light information to the circadian clock in the brain. The way in which light entrains the circadian clock appears, however, variable in different species. As do vertebrates, insects possess extraretinal photoreceptors in addition to their eyes (and ocelli) that are sometimes located close to (underneath) the eyes, but sometimes even in the central brain. These extraretinal photoreceptors contribute to entrainment of their circadian clocks to different degrees. The fruit fly Drosophila melanogaster is special, because it expresses the blue light-sensitive cryptochrome (CRY) directly in its circadian clock neurons, and CRY is usually regarded as the fly's main circadian photoreceptor. Nevertheless, recent studies show that the retinal and extraretinal eyes transfer light information to almost every clock neuron and that the eyes are similarly important for entraining the fly's activity rhythm as in other insects, or more generally spoken in other animals. Here, I compare the light input pathways between selected insect species with a focus on Drosophila's special case.

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“…The possible contribution of ONT light can only be minor in this context, however, since the light reaching the retina through the conventional pathway stimulates the photosensitive cells as well. Teleosts also possess several photosensitive brain areas, not only in the pineal but also throughout the deep brain, that are involved in many regulatory processes [ 33 ]. Both the translucency of the skull and the light guidance by the optic nerves could originally be adaptations that allow light to reach those brain areas.…”

Section: Resultsmentioning

confidence: 99%

Optic-nerve-transmitted eyeshine, a new type of light emission from fish eyes

et al. 2017

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BackgroundMost animal eyes feature an opaque pigmented eyecup to assure that light can enter from one direction only. We challenge this dogma by describing a previously unknown form of eyeshine resulting from light that enters the eye through the top of the head and optic nerve, eventually emanating through the pupil as a narrow beam: the Optic-Nerve-Transmitted (ONT) eyeshine. We characterize ONT eyeshine in the triplefin blenny Tripterygion delaisi (Tripterygiidae) in comparison to three other teleost species, using behavioural and anatomical observations, spectrophotometry, histology, and magnetic resonance imaging. The study’s aim is to identify the factors that determine ONT eyeshine occurrence and intensity, and whether these are specifically adapted for that purpose.ResultsONT eyeshine intensity benefits from locally reduced head pigmentation, a thin skull, the gap between eyes and forebrain, the potential light-guiding properties of the optic nerve, and, most importantly, a short distance between the head surface and the optic nerves.ConclusionsThe generality of these factors and the lack of specifically adapted features implies that ONT eyeshine is widespread among small fish species. Nevertheless, its intensity varies considerably, depending on the specific combination and varying expression of common anatomical features. We discuss whether ONT eyeshine might affect visual performance, and speculate about possible functions such as predator detection, camouflage, and intraspecific communication.Electronic supplementary materialThe online version of this article (doi:10.1186/s12983-017-0198-9) contains supplementary material, which is available to authorized users.

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Neuronal Organization of Deep Brain Opsin Photoreceptors in Adult Teleosts

Cited by 21 publications

References 81 publications

Interplay between the endocrine and circadian systems in fishes

Interplay between the endocrine and circadian systems in fishes

Light input pathways to the circadian clock of insects with an emphasis on the fruit fly Drosophila melanogaster

Optic-nerve-transmitted eyeshine, a new type of light emission from fish eyes

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