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Pomianowski K, Gozdowska M, Sokołowska E, Kulczykowska E. The cutaneous stress response system in three-spined stickleback and European flounder exposed to oxidative stress: Different mode of action. Comp Biochem Physiol A Mol Integr Physiol 2023; 285:111493. [PMID: 37541323 DOI: 10.1016/j.cbpa.2023.111493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 07/18/2023] [Accepted: 08/01/2023] [Indexed: 08/06/2023]
Abstract
In fish, the skin is directly exposed to multiple environmental stressors and provides the first line of defense against harmful external factors. It turned out that cortisol and melatonin (Mel) are involved in fish cutaneous stress response system (CSRS) similar to mammalian. This study investigates the mode of action of CSRS in two teleost species of different biology and skin characteristics, the three-spined stickleback and the European flounder, after exposure to oxidative stress induced by a potassium dichromate solution. The cutaneous stress response system presents different ways of action in two studied species: Mel concentration increases in the skin of both species, but cortisol concentration increases in the skin only in sticklebacks. Data suggest that stickleback skin cells can produce cortisol. However, cortisol is not involved in the response to oxidative stress in flounders. In stickleback skin, two genes encoding AANAT and ASMT/HIOMT (enzymes involved in Mel synthesis), aanat1a and asmt2, are expressed, but in flounder skin, only one, asmtl. Because gene expression does not change in stickleback skin after exposure to stress, the source of increased Mel is probably outside the skin. A lack of expression of the gene encoding AANAT in flounder skin strongly suggests that Mel is transported to the skin by the bloodstream from other sites of synthesis. Pigment dispersion in the skin after exposure to oxidative stress is found only in sticklebacks.
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Affiliation(s)
- Konrad Pomianowski
- Department of Genetics and Marine Biotechnology, Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55 Str., 81-712 Sopot, Poland
| | - Magdalena Gozdowska
- Department of Genetics and Marine Biotechnology, Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55 Str., 81-712 Sopot, Poland
| | - Ewa Sokołowska
- Department of Genetics and Marine Biotechnology, Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55 Str., 81-712 Sopot, Poland
| | - Ewa Kulczykowska
- Department of Genetics and Marine Biotechnology, Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55 Str., 81-712 Sopot, Poland.
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Örği E, Oğuz AR. Anatomical and histological investigation of the pineal gland in the lake van fish (Alburnus tarichi (Güldenstädt, 1814)). Anat Histol Embryol 2022; 51:427-434. [PMID: 35285548 DOI: 10.1111/ahe.12802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 02/01/2022] [Accepted: 03/01/2022] [Indexed: 11/30/2022]
Abstract
The pineal gland and melatonin secreted from the gland regulate the biological clock and adaptation to seasonal changes, glucose balance, nutrition and locomotor activities. In this study, the pineal gland of the Lake Van fish was examined anatomically and histologically. The melatonin level secreted from the pineal gland was determined in fish plasma sampled from both lakes and streams during reproduction migration. The pineal gland in the Lake Van fish, as in other teleost fish, is located in the head, under the translucent pineal window, which does not contain many pigment cells. The gland consists of pineal vesicle and pineal stalk parts on the dorsal sac in the Lake Van fish. It was determined that the pineal gland showed good vascularity. The presence of pinealocytes and different types of cells in the pineal organ was determined histologically. Pinealocytes were intensely localized in the lumen of the pineal vesicle. The plasma melatonin level increased in fish passing from lake to stream for reproductive migration.
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Affiliation(s)
- Elif Örği
- Department of Biology, Faculty of Science, Van Yüzüncü Yıl University, Van, Turkey
| | - Ahmet Regaib Oğuz
- Department of Biology, Faculty of Science, Van Yüzüncü Yıl University, Van, Turkey
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3
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Nisembaum LG, Loentgen G, L’Honoré T, Martin P, Paulin CH, Fuentès M, Escoubeyrou K, Delgado MJ, Besseau L, Falcón J. Transient Receptor Potential-Vanilloid (TRPV1-TRPV4) Channels in the Atlantic Salmon, Salmo salar. A Focus on the Pineal Gland and Melatonin Production. Front Physiol 2022; 12:784416. [PMID: 35069244 PMCID: PMC8782258 DOI: 10.3389/fphys.2021.784416] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 12/07/2021] [Indexed: 11/13/2022] Open
Abstract
Fish are ectotherm, which rely on the external temperature to regulate their internal body temperature, although some may perform partial endothermy. Together with photoperiod, temperature oscillations, contribute to synchronizing the daily and seasonal variations of fish metabolism, physiology and behavior. Recent studies are shedding light on the mechanisms of temperature sensing and behavioral thermoregulation in fish. In particular, the role of some members of the transient receptor potential channels (TRP) is being gradually unraveled. The present study in the migratory Atlantic salmon, Salmo salar, aims at identifying the tissue distribution and abundance in mRNA corresponding to the TRP of the vanilloid subfamilies, TRPV1 and TRPV4, and at characterizing their putative role in the control of the temperature-dependent modulation of melatonin production-the time-keeping hormone-by the pineal gland. In Salmo salar, TRPV1 and TRPV4 mRNA tissue distribution appeared ubiquitous; mRNA abundance varied as a function of the month investigated. In situ hybridization and immunohistochemistry indicated specific labeling located in the photoreceptor cells of the pineal gland and the retina. Additionally, TRPV analogs modulated the production of melatonin by isolated pineal glands in culture. The TRPV1 agonist induced an inhibitory response at high concentrations, while evoking a bell-shaped response (stimulatory at low, and inhibitory at high, concentrations) when added with an antagonist. The TRPV4 agonist was stimulatory at the highest concentration used. Altogether, the present results agree with the known widespread distribution and role of TRPV1 and TRPV4 channels, and with published data on trout (Oncorhynchus mykiss), leading to suggest these channels mediate the effects of temperature on S. salar pineal melatonin production. We discuss their involvement in controlling the timing of daily and seasonal events in this migratory species, in the context of an increasing warming of water temperatures.
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Affiliation(s)
- Laura Gabriela Nisembaum
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Guillaume Loentgen
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Thibaut L’Honoré
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Patrick Martin
- Conservatoire National du Saumon Sauvage, Chanteuges, France
| | - Charles-Hubert Paulin
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Michael Fuentès
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Karine Escoubeyrou
- SU, CNRS Fédération 3724, Observatoire Océanologique, Banyuls-sur-Mer, France
| | - María Jesús Delgado
- Departamento de Genética, Fisiología y Microbiologia, Facultad de Biología, Universidad Complutense de Madrid, Madrid, Spain
| | - Laurence Besseau
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Jack Falcón
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
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4
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Nisembaum LG, Martin P, Lecomte F, Falcón J. Melatonin and osmoregulation in fish: A focus on Atlantic salmon Salmo salar smoltification. J Neuroendocrinol 2021; 33:e12955. [PMID: 33769643 DOI: 10.1111/jne.12955] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 02/07/2021] [Accepted: 02/09/2021] [Indexed: 10/21/2022]
Abstract
Part of the life cycle of several fish species includes important salinity changes, as is the case for the sea bass (Dicentrarchus labrax) or the Atlantic salmon (Salmo salar). Salmo salar juveniles migrate downstream from their spawning sites to reach seawater, where they grow and become sexually mature. The process of preparation enabling juveniles to migrate downstream and physiologically adapt to seawater is called smoltification. Daily and seasonal variations of photoperiod and temperature play a role in defining the timing of smoltification, which may take weeks to months, depending on the river length and latitude. Smoltification is characterised by a series of biochemical, physiological and behavioural changes within the neuroendocrine axis. This review discusses the current knowledge and gaps related to the neuroendocrine mechanisms that mediate the effects of light and temperature on smoltification. Studies performed in S. salar and other salmonids, as well as in other species undergoing important salinity changes, are reviewed, and a particular emphasis is given to the pineal hormone melatonin and its possible role in osmoregulation. The daily and annual variations of plasma melatonin levels reflect corresponding changes in external photoperiod and temperature, which suggests that the hormonal time-keeper melatonin might contribute to controlling smoltification. Here, we review studies on (i) the impact of pinealectomy and/or melatonin administration on smoltification; (ii) melatonin interactions with hormones involved in osmoregulation (e.g., prolactin, growth hormone and cortisol); (iii) the presence of melatonin receptors in tissues involved in osmoregulation; and (iv) the impacts of salinity changes on melatonin receptors and circulating melatonin levels. Altogether, these studies show evidence indicating that melatonin interacts with the neuroendocrine pathways controlling smoltification, although more information is needed to clearly decipher its mechanisms of action.
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Affiliation(s)
- Laura Gabriela Nisembaum
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins, (BIOM), Banyuls-sur-Mer, France
| | - Patrick Martin
- Conservatoire National du Saumon Sauvage, Chanteuges, France
| | - Frédéric Lecomte
- Ministère des Forêts, de la Faune et des Parcs, Direction de l'expertise sur la faune aquatique, Québec, Canada
| | - Jack Falcón
- Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), MNHN, CNRS 7208, SU, IRD 207, UCN, UA, Muséum National d'Histoire Naturelle, Paris, France
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Nisembaum LG, Martin P, Fuentes M, Besseau L, Magnanou E, McCormick SD, Falcón J. Effects of a temperature rise on melatonin and thyroid hormones during smoltification of Atlantic salmon, Salmo salar. J Comp Physiol B 2020; 190:731-748. [PMID: 32880666 DOI: 10.1007/s00360-020-01304-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 07/20/2020] [Accepted: 08/09/2020] [Indexed: 11/28/2022]
Abstract
Smoltification prepares juvenile Atlantic salmon (Salmo salar) for downstream migration. Dramatic changes characterize this crucial event in the salmon's life cycle, including increased gill Na+/K+-ATPase activity (NKA) and plasma hormone levels. The triggering of smoltification relies on photoperiod and is modulated by temperature. Both provide reliable information, to which fish have adapted for thousands of years, that allows deciphering daily and calendar time. Here we studied the impact of different photoperiod (natural, sustained winter solstice) and temperature (natural, ~ + 4° C) combinations, on gill NKA, plasma free triiodothyronine (T3) and thyroxine (T4), and melatonin (MEL; the time-keeping hormone), throughout smoltification. We also studied the impact of temperature history on pineal gland MEL production in vitro. The spring increase in gill NKA was less pronounced in smolts kept under sustained winter photoperiod and/or elevated temperature. Plasma thyroid hormone levels displayed day-night variations, which were affected by elevated temperature, either independently from photoperiod (decrease in T3 levels) or under natural photoperiod exclusively (increase in T4 nocturnal levels). Nocturnal MEL secretion was potentiated by the elevated temperature, which also altered the MEL profile under sustained winter photoperiod. Temperature also affected pineal MEL production in vitro, a response that depended on previous environmental acclimation of the organ. The results support the view that the salmon pineal is a photoperiod and temperature sensor, highlight the complexity of the interaction of these environmental factors on the endocrine system of S. salar, and indicate that climate change might compromise salmon's time "deciphering" during smoltification, downstream migration and seawater residence.
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Affiliation(s)
- Laura Gabriela Nisembaum
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins, BIOM, 66650, Banyuls-sur-Mer, France.
| | - Patrick Martin
- Conservatoire National du Saumon Sauvage, 43300, Chanteuges, France
| | - Michael Fuentes
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins, BIOM, 66650, Banyuls-sur-Mer, France
| | - Laurence Besseau
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins, BIOM, 66650, Banyuls-sur-Mer, France
| | - Elodie Magnanou
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins, BIOM, 66650, Banyuls-sur-Mer, France
| | - Stephen D McCormick
- S.O. Conte Anadromous Fish Research Laboratory, U.S. Geological Survey, Leetown Science Center, Turners Falls, MA, USA
| | - Jack Falcón
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins, BIOM, 66650, Banyuls-sur-Mer, France.,Biologie des Organismes et Ecosystèmes Aquatiques (BOREA) MNHN, CNRS 7208, UPMC, IRD 207, UCN, UA, Muséum National d'Histoire Naturelle, Paris Cedex, France
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6
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Kupprat F, Hölker F, Kloas W. Can skyglow reduce nocturnal melatonin concentrations in Eurasian perch? ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 262:114324. [PMID: 32179225 DOI: 10.1016/j.envpol.2020.114324] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 01/05/2020] [Accepted: 03/02/2020] [Indexed: 05/10/2023]
Abstract
Artificial light at night (ALAN) changes the natural rhythm of light and darkness and can impair the biorhythms of animals, for example the nocturnal melatonin production of vertebrates, which serves as a proxy for daily physiological rhythms. Freshwater fish are exposed to ALAN in large urban and suburban areas in the form of direct light or in the form of skyglow, a diffuse brightening of the night sky through the scattered light reflected by clouds, atmospheric molecules, and particles in the air. However, investigations on the sensitivity of melatonin production of fish towards low intensities of ALAN in the range of typical skyglow are rare. Therefore, we exposed Eurasian perch (Perca fluviatilis) to nocturnal illumination levels of 0.01 lx, 0.1 lx and 1 lx and a control group with dark nights and daylight intensities of 2900 lx in all groups. After ten days of exposure to the experimental conditions, tank water was non-invasively sampled every 3 h over a 24 h period and melatonin was measured by ELISA. Melatonin was gradually reduced in all treatments with increasing intensity of ALAN whereas rhythmicity was maintained in all treatment groups although at 1 lx not all evaluated parameters confirmed rhythmicity. These results show a high sensitivity of Eurasian perch towards ALAN indicating that low light intensities of 0.01 lx and 0.1 lx as they occur in urban and suburban areas in the form of skyglow can affect the physiology of Eurasian perch. Furthermore, we highlight how this may impact perch in their sensitivity towards lunar rhythms and the role of skyglow for biorhythms of temperate freshwater fish.
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Affiliation(s)
- Franziska Kupprat
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587, Berlin, Germany; Faculty of Life Sciences, Humboldt University, Invalidenstr. 42, 10099, Berlin, Germany.
| | - Franz Hölker
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587, Berlin, Germany.
| | - Werner Kloas
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587, Berlin, Germany; Faculty of Life Sciences, Humboldt University, Invalidenstr. 42, 10099, Berlin, Germany.
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7
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Servili A, Canario AVM, Mouchel O, Muñoz-Cueto JA. Climate change impacts on fish reproduction are mediated at multiple levels of the brain-pituitary-gonad axis. Gen Comp Endocrinol 2020; 291:113439. [PMID: 32061640 DOI: 10.1016/j.ygcen.2020.113439] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 02/11/2020] [Accepted: 02/11/2020] [Indexed: 11/30/2022]
Abstract
Anthropogenic emissions of carbon dioxide in the atmosphere have generated rapid variations in atmospheric composition which drives major climate changes. Climate change related effects include changes in physico-chemical proprieties of sea and freshwater, such as variations in water temperature, salinity, pH/pCO2 and oxygen content, which can impact fish critical physiological functions including reproduction. In this context, the main aim of the present review is to discuss how climate change related effects (variation in water temperature and salinity, increases in duration and frequency of hypoxia events, water acidification) would impact reproduction by affecting the neuroendocrine axis (brain-pituitary-gonad axis). Variations in temperature and photoperiod regimes are known to strongly affect sex differentiation and the timing and phenology of spawning period in several fish species. Temperature mainly acts at the level of gonad by interfering with steroidogenesis, (notably on gonadal aromatase activity) and gametogenesis. Temperature is also directly involved in the quality of released gametes and embryos development. Changes in salinity or water acidification are especially associated with reduction of sperm quality and reproductive output. Hypoxia events are able to interact with gonad steroidogenesis by acting on the steroids precursor cholesterol availability or directly on aromatase action, with an impact on the quality of gametes and reproductive success. Climate change related effects on water parameters likely influence also the reproductive behavior of fish. Although the precise mechanisms underlying the regulation of these effects are not always understood, in this review we discuss different hypothesis and propose future research perspectives.
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Affiliation(s)
- Arianna Servili
- Ifremer, Univ Brest, CNRS, IRD, LEMAR, F-29280 Plouzane, France.
| | - Adelino V M Canario
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Olivier Mouchel
- Ifremer, Univ Brest, CNRS, IRD, LEMAR, F-29280 Plouzane, France
| | - José Antonio Muñoz-Cueto
- Faculty of Marine and Environmental Sciences, INMAR, Department of Biology, University of Cádiz, Marine Campus of International Excellence (CEIMAR), Agrifood Campus of International Excellence (ceiA3) and European University of the Seas (SEA-EU), E11510 Puerto Real, Spain
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8
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Pomianowski K, Gozdowska M, Burzyński A, Kalamarz-Kubiak H, Sokołowska E, Kijewska A, Kulczykowska E. A study of aanat and asmt expression in the three-spined stickleback eye and skin: Not only “on the way to melatonin”. Comp Biochem Physiol A Mol Integr Physiol 2020; 241:110635. [DOI: 10.1016/j.cbpa.2019.110635] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 11/22/2019] [Accepted: 12/06/2019] [Indexed: 02/05/2023]
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Premabati Y, Singh KM, Gupta BBP. Opposite effects of photoperiod and temperature on circadian rhythms of pineal arylalkylamine N-acetyltransferas (AANAT) activity and circulating levels of thyroid hormones in airbreathing catfish, Clarias gariepinus. BIOL RHYTHM RES 2020. [DOI: 10.1080/09291016.2020.1734370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Yumkhaibam Premabati
- Environmental Endocrinology Laboratory, Department of Zoology, North-Eastern Hill University, Shillong, India
| | - Kshetrimayum Manisana Singh
- Environmental Endocrinology Laboratory, Department of Zoology, North-Eastern Hill University, Shillong, India
| | - Braj Bansh Prasad Gupta
- Environmental Endocrinology Laboratory, Department of Zoology, North-Eastern Hill University, Shillong, India
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Saha S, Singh KM, Gupta BBP. Melatonin synthesis and clock gene regulation in the pineal organ of teleost fish compared to mammals: Similarities and differences. Gen Comp Endocrinol 2019; 279:27-34. [PMID: 30026020 DOI: 10.1016/j.ygcen.2018.07.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 07/12/2018] [Accepted: 07/15/2018] [Indexed: 02/07/2023]
Abstract
The pineal organ of all vertebrates synthesizes and secretes melatonin in a rhythmic manner due to the circadian rhythm in the activity of arylalkylamine N-acetyltransferase (AANAT) - the rate-limiting enzyme in melatonin synthesis pathway. Nighttime increase in AANAT activity and melatonin synthesis depends on increased expression of aanat gene (a clock-controlled gene) and/or post-translation modification of AANAT protein. In mammalian and avian species, only one aanat gene is expressed. However, three aanat genes (aanat1a, aanat1b, and aanat2) are reported in fish species. While aanat1a and aanat1b genes are expressed in the fish retina, the nervous system and other peripheral tissues, aanat2 gene is expressed exclusively in the fish pineal organ. Clock genes form molecular components of the clockwork, which regulates clock-controlled genes like aanat gene. All core clock genes (i.e., clock, bmal1, per1, per2, per3, cry1 and cry2) and aanat2 gene (a clock-controlled gene) are expressed in the pineal organ of several fish species. There is a large body of information on regulation of clock genes, aanat gene and melatonin synthesis in the mammalian pineal gland. However, the information available on clock genes, aanat genes and melatonin synthesis in photoreceptive pineal organ of teleosts is fragmentary and not well documented. Therefore, we have reviewed published information on rhythmic expression of clock genes, aanat genes as well as synthesis of melatonin, and their regulation by photoperiod and temperature in teleostean pineal organ as compared to mammalian pineal gland. A critical analysis of the literature suggests that in contrast to the mammalian pineal gland, the pineal organ of teleosts (except salmonids) possesses a well developed indigenous clock composed of clock genes for regulation of rhythmic expression of aanat2 gene and melatonin synthesis. Further, the fish pineal organ also possesses essential molecular components for responding to light and temperature directly. The fish pineal organ seems to act as a potential master biological clock in most of the teleosts.
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Affiliation(s)
- Saurav Saha
- Environmental Endocrinology Laboratory, Department of Zoology, North-Eastern Hill University, Shillong 793022, India
| | - Kshetrimayum Manisana Singh
- Environmental Endocrinology Laboratory, Department of Zoology, North-Eastern Hill University, Shillong 793022, India
| | - Braj Bansh Prasad Gupta
- Environmental Endocrinology Laboratory, Department of Zoology, North-Eastern Hill University, Shillong 793022, India.
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Chi L, Li X, Liu Q, Liu Y. Photoperiod may regulate growth via leptin receptor A1 in the hypothalamus and saccus vasculosus of Atlantic salmon ( Salmo salar). Anim Cells Syst (Seoul) 2019; 23:200-208. [PMID: 31231584 PMCID: PMC6566995 DOI: 10.1080/19768354.2019.1595138] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 02/14/2019] [Accepted: 02/17/2019] [Indexed: 10/27/2022] Open
Abstract
Photoperiod is believed to regulate growth in fish, although the mechanism involved is still unclear. In this paper, we report a relationship between leptin-receptor A1 (AsLRa1), melatonin-receptor (AsMR) and photoperiod in Atlantic salmon. Atlantic salmon (mean weight 1071.70 ± 155.54 g) were reared under six photoperiod regimes, four constant light regimes 24L:0D, 18L:6D, 12L:12D and 8L:16D, hours of light (L) and dark (D) and two varying light regimes, LL-SL = 24L:0D-8L:16D, and SL-LL = 8L:16D-24L:0D over a period of seven months. The results showed that AsLRa1 transcripts were mainly existed in the hypothalamus and saccus vasculosus (SV), AsMR was mainly expressed in the hypothalamus. Long photoperiod inhibited the expression of AsLRa1 and AsMR transcripts in the Atlantic salmon brain. The expression pattern of AsLRa1 was similar to the expression pattern of AsMR in the hypothalamus. Food intake was higher in fish with lower AsLRa1 transcript levels. This demonstrated that photoperiod influenced somatic growth by changing expression of AsLRa1 in the hypothalamus and SV to affect appetite. In addition, we found that the SV appears to act as a seasonal sensor regulating reproduction in a similar way to the hypothalamus.
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Affiliation(s)
- Liang Chi
- Qingdao Agricultural University, Qingdao, People’s Republic of China
| | - Xian Li
- Institute of Oceanology Chinese Academy of Sciences, Qingdao, People’s Republic of China
| | - Qinghua Liu
- Institute of Oceanology Chinese Academy of Sciences, Qingdao, People’s Republic of China
| | - Ying Liu
- Institute of Oceanology Chinese Academy of Sciences, Qingdao, People’s Republic of China
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12
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Sánchez-Vázquez FJ, López-Olmeda JF, Vera LM, Migaud H, López-Patiño MA, Míguez JM. Environmental Cycles, Melatonin, and Circadian Control of Stress Response in Fish. Front Endocrinol (Lausanne) 2019; 10:279. [PMID: 31244768 PMCID: PMC6579845 DOI: 10.3389/fendo.2019.00279] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 04/16/2019] [Indexed: 01/10/2023] Open
Abstract
Fish have evolved a biological clock to cope with environmental cycles, so they display circadian rhythms in most physiological functions including stress response. Photoperiodic information is transduced by the pineal organ into a rhythmic secretion of melatonin, which is released into the blood circulation with high concentrations at night and low during the day. The melatonin rhythmic profile is under the control of circadian clocks in most fish (except salmonids), and it is considered as an important output of the circadian system, thus modulating most daily behavioral and physiological rhythms. Lighting conditions (intensity and spectrum) change in the underwater environment and affect fish embryo and larvae development: constant light/darkness or red lights can lead to increased malformations and mortality, whereas blue light usually results in best hatching rates and growth performance in marine fish. Many factors display daily rhythms along the hypothalamus-pituitary-interrenal (HPI) axis that controls stress response in fish, including corticotropin-releasing hormone (Crh) and its binding protein (Crhbp), proopiomelanocortin A and B (Pomca and Pomcb), and plasma cortisol, glucose, and lactate. Many of these circadian rhythms are under the control of endogenous molecular clocks, which consist of self-sustained transcriptional-translational feedback loops involving the cyclic expression of circadian clock genes (clock, bmal, per, and cry) which persists under constant light or darkness. Exposing fish to a stressor can result in altered rhythms of most stress indicators, such as cortisol, glucose, and lactate among others, as well as daily rhythms of most behavioral and physiological functions. In addition, crh and pomca expression profiles can be affected by other factors such as light spectrum, which strongly influence the expression profile of growth-related (igf1a, igf2a) genes. Additionally, the daily cycle of water temperature (warmer at day and cooler at night) is another factor that has to be considered. The response to any acute stressor is not only species dependent, but also depends on the time of the day when the stress occurs: nocturnal species show higher responses when stressed during day time, whereas diurnal fish respond stronger at night. Melatonin administration in fish has sedative effects with a reduction in locomotor activity and cortisol levels, as well as reduced liver glycogen and dopaminergic and serotonergic activities within the hypothalamus. In this paper, we are reviewing the role of environmental cycles and biological clocks on the entrainment of daily rhythms in the HPI axis and stress responses in fish.
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Affiliation(s)
| | | | - Luisa Maria Vera
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | - Herve Migaud
- Institute of Aquaculture, University of Stirling, Stirling, United Kingdom
| | - Marcos Antonio López-Patiño
- Laboratory Animal Physiology, Department Biology and Health Science, Faculty of Biology and Centro Singular de Investigación Mariña-ECIMAT, University of Vigo, Vigo, Spain
| | - Jesús M. Míguez
- Laboratory Animal Physiology, Department Biology and Health Science, Faculty of Biology and Centro Singular de Investigación Mariña-ECIMAT, University of Vigo, Vigo, Spain
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Li Y, Lv Y, Bian C, You X, Deng L, Shi Q. A Comparative Genomic Survey Provides Novel Insights into Molecular Evolution of l-Aromatic Amino Acid Decarboxylase in Vertebrates. Molecules 2018; 23:molecules23040917. [PMID: 29659490 PMCID: PMC6017361 DOI: 10.3390/molecules23040917] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 04/10/2018] [Accepted: 04/13/2018] [Indexed: 11/21/2022] Open
Abstract
Melatonin is a pleiotropic molecule with various important physiological roles in vertebrates. l-aromatic amino acid decarboxylase (AAAD) is the second enzyme for melatonin synthesis. By far, a clear-cut gene function of AAAD in the biosynthesis of melatonin has been unclear in vertebrates. Here, we provide novel insights into the evolution of AAAD based on 77 vertebrate genomes. According to our genome-wide alignments, we extracted a total of 151 aaad nucleotide sequences. A phylogenetic tree was constructed on the basis of these sequences and corresponding protein alignments, indicating that tetrapods and diploid bony fish genomes contained one aaad gene and a new aaad-like gene, which formed a novel AAAD family. However, in tetraploid teleosts, there were two copies of the aaad gene due to whole genome duplication. A subsequent synteny analysis investigated 81 aaad sequences and revealed their collinearity and systematic evolution. Interestingly, we discovered that platypus (Ornithorhynchus anatinus), Atlantic cod (Guadus morhua), Mexican tetra (Astyanax mexicanus), and a Sinocyclocheilus cavefish (S. anshuiensis) have long evolutionary branches in the phylogenetic topology. We also performed pseudogene identification and selection pressure analysis; however, the results revealed a deletion of 37 amino acids in Atlantic cod and premature stop codons in the cave-restricted S. anshuiensis and A. mexicanus, suggesting weakening or disappearing rhythms in these cavefishes. Selective pressure analysis of aaad between platypus and other tetrapods showed that rates of nonsynonymous (Ka) and synonymous (Ks) substitutions were higher when comparing the platypus to other representative tetrapods, indicating that, in this semiaquatic mammal, the aaad gene experienced selection during the process of evolution. In summary, our current work provides novel insights into aaad genes in vertebrates from a genome-wide view.
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Affiliation(s)
- Yanping Li
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
| | - Yunyun Lv
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen 518083, China.
| | - Chao Bian
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
| | - Xinxin You
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
| | - Li Deng
- Laboratory of Aquatic Genomics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China.
| | - Qiong Shi
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen 518083, China.
- Laboratory of Aquatic Genomics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China.
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viviD D, Bentley GE. Seasonal Reproduction in Vertebrates: Melatonin Synthesis, Binding, and Functionality Using Tinbergen's Four Questions. Molecules 2018; 23:E652. [PMID: 29534047 PMCID: PMC6017951 DOI: 10.3390/molecules23030652] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/11/2018] [Accepted: 02/13/2018] [Indexed: 12/15/2022] Open
Abstract
One of the many functions of melatonin in vertebrates is seasonal reproductive timing. Longer nights in winter correspond to an extended duration of melatonin secretion. The purpose of this review is to discuss melatonin synthesis, receptor subtypes, and function in the context of seasonality across vertebrates. We conclude with Tinbergen's Four Questions to create a comparative framework for future melatonin research in the context of seasonal reproduction.
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Affiliation(s)
- Dax viviD
- Berkeley Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
| | - George E Bentley
- Berkeley Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
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15
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Prokkola JM, Nikinmaa M, Lewis M, Anttila K, Kanerva M, Ikkala K, Seppänen E, Kolari I, Leder EH. Cold temperature represses daily rhythms in the liver transcriptome of a stenothermal teleost under decreasing day length. ACTA ACUST UNITED AC 2018; 221:jeb.170670. [PMID: 29361589 DOI: 10.1242/jeb.170670] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 01/15/2018] [Indexed: 12/19/2022]
Abstract
The climate-change-driven increase in temperature is occurring rapidly and decreasing the predictability of seasonal rhythms at high latitudes. It is therefore urgent to understand how a change in the relationship between photoperiod and temperature can affect ectotherms in these environments. We tested whether temperature affects daily rhythms of transcription in a cold-adapted salmonid using high-throughput RNA sequencing. Arctic char (Salvelinus alpinus) from a subarctic population were reared at a high and a low temperature (15 and 8°C) for 1 month under natural, decreasing day length during late summer. Liver transcriptomes were compared between samples collected in the middle and towards the end of the light period and in the middle of the dark period. Daily variation in transcription was lower in fish from the low temperature compared with strong daily variation in warm-acclimated fish, suggesting that cold temperatures dampen the cycling of transcriptional rhythms under a simultaneously decreasing day length. Different circadian clock genes had divergent expression patterns, responding either by decreased expression or by increased rhythmicity at 15°C compared with 8°C. The results point out mechanisms that can affect the ability of fish to adapt to increasing temperatures caused by climate change.
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Affiliation(s)
- Jenni M Prokkola
- Department of Biology, University of Turku, FI-20014 Turku, Finland .,Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland
| | - Mikko Nikinmaa
- Department of Biology, University of Turku, FI-20014 Turku, Finland
| | - Mario Lewis
- Department of Biology, University of Turku, FI-20014 Turku, Finland
| | - Katja Anttila
- Department of Biology, University of Turku, FI-20014 Turku, Finland
| | - Mirella Kanerva
- Department of Biology, University of Turku, FI-20014 Turku, Finland
| | - Kaisa Ikkala
- Department of Biology, University of Turku, FI-20014 Turku, Finland
| | - Eila Seppänen
- Natural Resources Institute Finland (Luke), Laasalantie 9, FI-58175 Enonkoski, Finland
| | - Irma Kolari
- Natural Resources Institute Finland (Luke), Laasalantie 9, FI-58175 Enonkoski, Finland
| | - Erica H Leder
- Department of Biology, University of Turku, FI-20014 Turku, Finland.,Natural History Museum, University of Oslo, Oslo NO-0318, Norway
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16
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Voeten DFAE, Reich T, Araújo R, Scheyer TM. Synchrotron microtomography of a Nothosaurus marchicus skull informs on nothosaurian physiology and neurosensory adaptations in early Sauropterygia. PLoS One 2018; 13:e0188509. [PMID: 29298295 PMCID: PMC5751976 DOI: 10.1371/journal.pone.0188509] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 11/08/2017] [Indexed: 02/06/2023] Open
Abstract
Nothosaurs form a subclade of the secondarily marine Sauropterygia that was well represented in late Early to early Late Triassic marine ecosystems. Here we present and discuss the internal skull anatomy of the small piscivorous nothosaur Nothosaurus marchicus from coastal to shallow marine Lower Muschelkalk deposits (Anisian) of Winterswijk, The Netherlands, which represents the oldest sauropterygian endocast visualized to date. The cranial endocast is only partially encapsulated by ossified braincase elements. Cranial flattening and lateral constriction by hypertrophied temporal musculature grant the brain a straight, tubular geometry that lacks particularly well-developed cerebral lobes but does potentially involve distinguishable optic lobes, suggesting vision may have represented an important sense during life. Despite large orbit size, the circuitous muscular pathway linking the basisphenoidal and orbital regions indicates poor oculomotor performance. This suggests a rather fixed ocular orientation, although eye placement and neck manoeuvrability could have enabled binocular if not stereoscopic vision. The proportionally large dorsal projection of the braincase endocast towards the well-developed pineal foramen advocates substantial dependence on the corresponding pineal system in vivo. Structures corroborating keen olfactory or acoustic senses were not identified. The likely atrophied vomeronasal organ argues against the presence of a forked tongue in Nothosaurus, and the relative positioning of external and internal nares contrasts respiratory configurations proposed for pistosauroid sauropterygians. The antorbital domain furthermore accommodates a putative rostral sensory plexus and pronounced lateral nasal glands that were likely exapted as salt glands. Previously proposed nothosaurian 'foramina eustachii' arose from architectural constraints on braincase development rather than representing functional foramina. Several modifications to brain shape and accessory organs were achieved through heterochronic development of the cranium, particularly the braincase. In summary, the cranium of Nothosaurus marchicus reflects important physiological and neurosensory adaptations that enabled the group's explosive invasion of shallow marine habitats in the late Early Triassic.
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Affiliation(s)
- Dennis F. A. E. Voeten
- European Synchrotron Radiation Facility, Grenoble, France
- Department of Zoology and Laboratory of Ornithology, Palacký University, Olomouc, Czech Republic
| | - Tobias Reich
- University of Zurich, Palaeontological Institute and Museum, Zurich, Switzerland
| | - Ricardo Araújo
- Institute for Plasma Research and Nuclear Fusion, Technical University of Lisbon, Lisbon, Portugal
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
- Institute of Evolutionary Sciences, University of Montpellier 2, Montpellier, France
| | - Torsten M. Scheyer
- University of Zurich, Palaeontological Institute and Museum, Zurich, Switzerland
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17
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Singh KM, Saha S, Gupta BBP. Season-dependent effects of photoperiod and temperature on circadian rhythm of arylalkylamine N -acetyltransferase2 gene expression in pineal organ of an air-breathing catfish, Clarias gariepinus. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2017; 173:140-149. [DOI: 10.1016/j.jphotobiol.2017.05.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 05/23/2017] [Accepted: 05/25/2017] [Indexed: 11/28/2022]
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18
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Premabati Y, Singh KM, Gupta BBP. Inverse relationship between diurnal rhythms in plasma levels of thyroid hormones and pineal arylalkylamine-N-acetyltransferase (AANAT) activity in an air-breathing fish,Clarias gariepinus. BIOL RHYTHM RES 2017. [DOI: 10.1080/09291016.2017.1350443] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Y. Premabati
- Environmental Endocrinology Laboratory, Department of Zoology, North-Eastern Hill University, Shillong, India
| | - K. M. Singh
- Environmental Endocrinology Laboratory, Department of Zoology, North-Eastern Hill University, Shillong, India
| | - Braj B. P. Gupta
- Environmental Endocrinology Laboratory, Department of Zoology, North-Eastern Hill University, Shillong, India
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19
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Kulczykowska E, Kleszczyńska A, Gozdowska M, Sokołowska E. The time enzyme in melatonin biosynthesis in fish: Day/night expressions of three aralkylamine N -acetyltransferase genes in three-spined stickleback. Comp Biochem Physiol A Mol Integr Physiol 2017; 208:46-53. [DOI: 10.1016/j.cbpa.2017.03.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 03/09/2017] [Accepted: 03/11/2017] [Indexed: 01/15/2023]
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20
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Cowan M, Azpeleta C, López-Olmeda JF. Rhythms in the endocrine system of fish: a review. J Comp Physiol B 2017; 187:1057-1089. [DOI: 10.1007/s00360-017-1094-5] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Revised: 03/20/2017] [Accepted: 04/06/2017] [Indexed: 12/20/2022]
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21
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Rahman MS, Kim BH, Takemura A, Park CB, Lee YD. Effects of Moonlight Exposure on Plasma Melatonin Rhythms in the Seagrass Rabbitfish, Siganus Canaliculatus. J Biol Rhythms 2016; 19:325-34. [PMID: 15245651 DOI: 10.1177/0748730404266712] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Influences of light-dark (LD) cycle and moonlight exposure on plasma melatonin rhythms in the seagrass rabbitfish, Siganus canaliculatus, a lunar synchronized spawner, were determined by time-resolved fluoroimmunoassay (TR-FIA). When the fish were exposed to a natural LD (12:12) cycle, plasma melatonin levels exhibited a clear daily rhythm, with higher levels at midnight and lower levels during the day. These rhythms were not evident under either constant light (LL) or constant dark (DD) conditions. Plasma melatonin levels under LL condition were low and high under DD condition. These results indicate that plasma melatonin rhythms are driven by LD cycle in this species. When the fish were exposed to the 4 lunar phases, plasma melatonin levels around the new moon were significantly higher than during the first quarter moon and the full moon. Exposure to experimentalnewmoonand full moonconditions caused significant increases and decreases of plasma melatonin levels, respectively. The synchronous rhythmicity of melatonin levels in the plasma support the hypothesis that the seagrass rabbitfish perceives moonlight intensity and responds with secretion of melatonin into the bloodstream.
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Affiliation(s)
- Md Saydur Rahman
- Marine Science Institute, University of Texas at Austin, 750 Channel View Drive, Port Aransas, Texas 78373, USA.
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22
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Badruzzaman M, Bapary MAJ, Takemura A. Possible roles of photoperiod and melatonin in reproductive activity via changes in dopaminergic activity in the brain of a tropical damselfish, Chrysiptera cyanea. Gen Comp Endocrinol 2013; 194:240-7. [PMID: 24090612 DOI: 10.1016/j.ygcen.2013.09.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 09/15/2013] [Accepted: 09/21/2013] [Indexed: 12/20/2022]
Abstract
The perception of periodical change in photoperiodic conditions by photosensory organs is the first step to initiating reproductive activity in fish. To date, it is not known how photoperiodic cues are endogenously transduced to the endocrine network of the brain-pituitary-gonad axis after the perception of photoperiodic stimuli. Because dopamine (DA) inhibits gonadotropin release from the pituitary in certain teleosts, it is likely that it is a key mediator of photoperiodic stimulation. We examined the relationship between photoperiodicity and dopaminergic activity in the brain of the sapphire devil Chrysiptera cyanea, which is a reef-associated damselfish and uses long-day conditions for triggering gonadal development. DA and 3,4-dihydroxyphenylacetic acid (DOPAC; DA metabolite) were measured electrochemically with a high-performance liquid chromatography (HPLC) system, and then DOPAC/DA (metabolic rate of DA activity) was determined. Daily fluctuations in DA, DOPAC, and DOPAC/DA were observed under LD 12:12. Light-dark cycles, but not constant conditions, influenced DA and DOPAC contents as well as DOPAC/DA in the brain; DOPAC content and DOPAC/DA increased under LD 14:10, while DA increased under LD 10:14. When fish were reared in melatonin-containing water, DOPAC and DOPAC/DA, but not DA, decreased within 6h after treatment. Culturing the isolated brain with melatonin stimulated DA release into the medium. Active vitellogenesis in females during the reproductive season was suppressed by melatonin treatment. These results suggest that day length alters DA metabolism in the brain of the sapphire devil through fluctuations in melatonin caused by external light stimuli, and that inhibitory effects on gonadal development are partially controlled by interactions within the melatonin-DA system.
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Affiliation(s)
- Muhammad Badruzzaman
- Department of Chemistry, Biology and Marine Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan
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23
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Cazaméa-Catalan D, Magnanou E, Helland R, Besseau L, Boeuf G, Falcón J, Jørgensen EH. Unique arylalkylamine N-acetyltransferase-2 polymorphism in Salmonids and profound variations in thermal stability and catalytic efficiency conferred by two residues. J Exp Biol 2013; 216:1938-48. [DOI: 10.1242/jeb.080960] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Summary
Melatonin contributes to synchronizing major biological and behavioral functions to the cyclic changes in the environment. The arylalkylamine N-acetyltransferase (AANAT) is responsible for a daily rhythm in melatonin secretion. Teleost possess two enzyme forms, AANAT1 and AANAT2, preferentially expressed in the retina and pineal organ, respectively. The concomitant action of light and temperature shapes the daily and seasonal changes in melatonin secretion: the former controls duration while the latter modulates amplitude. Investigating the respective roles of light and temperature is particularly relevant in the context of a global warming likely to affect the way fish decode and anticipate seasonal changes with dramatic consequences on their physiology and behavior. Here we investigated the impact of temperature on pineal melatonin secretion of a migratory species, the Arctic charr (Salvelinus alpinus), the northernmost living and cold adapted salmonid. We show that temperature impacts directly melatonin production in cultured pineal organs. We also show that one organ expresses two AANAT2 transcripts displaying high similarity between them and with trout Oncorhynchus mykiss AANAT2, differing by only two amino acid sites. We compared the kinetics and 3D models of these enzymes as well as of a chimeric construct, particularly with regard to their response to temperature. Our study brings interesting and totally new information on the evolutionary diversity of AANAT enzymes in Teleost and on the role played by specific residues in the catalytic properties of the enzymes.
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Affiliation(s)
| | | | | | | | | | - Jack Falcón
- CNRS, Biologie Intégrative des Organismes Marins
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Cazaméa-Catalan D, Magnanou E, Helland R, Vanegas G, Besseau L, Boeuf G, Paulin CH, Jørgensen EH, Falcón J. Functional diversity of Teleost arylalkylamineN-acetyltransferase-2: is thetimezymeevolution driven by habitat temperature? Mol Ecol 2012; 21:5027-41. [DOI: 10.1111/j.1365-294x.2012.05725.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 06/21/2012] [Accepted: 06/28/2012] [Indexed: 01/19/2023]
Affiliation(s)
| | | | - R. Helland
- Norstruct; Department of Chemistry; Faculty of Science and Technology; University of Tromsø; N-9037; Tromsø; Norway
| | - G. Vanegas
- Cátedra de Fisiología Normal; Escuela de Medicina “José María Vargas”; Facultad de Medicina; Universidad Central de Venezuela; Caracas; Venezuela
| | | | | | | | - E. H. Jørgensen
- Department of Arctic and Marine Biology; Faculty of Biosciences; Fisheries and Economy; University of Tromsø; N-9037; Tromsø; Norway
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25
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Zeman M, Herichová I. Circadian melatonin production develops faster in birds than in mammals. Gen Comp Endocrinol 2011; 172:23-30. [PMID: 21199656 DOI: 10.1016/j.ygcen.2010.12.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Accepted: 12/24/2010] [Indexed: 11/17/2022]
Abstract
The development of circadian rhythmicity of melatonin biosynthesis in the pineal gland starts during embryonic period in birds while it is delayed to the postnatal life in mammals. Daily rhythms of melatonin in isolated pinealocytes and in intact pineal glands under in vivo conditions were demonstrated during the last third of embryonic development in chick embryos, with higher levels during the dark (D) than during the light (L) phase. In addition to the LD cycle, rhythmic temperature changes with the amplitude of 4.5°C can entrain rhythmic melatonin biosynthesis in chick embryos, with higher concentrations found during the low-temperature phase (33.0 vs 37.5°C). Molecular clockwork starts to operate during the embryonic life in birds in line with the early development of melatonin rhythmicity. Expression of per2 and cry genes is rhythmic at least at day 16 and 18, respectively, and the circadian system operates in a mature-like manner soon after hatching. Rhythmic oscillations are detected earlier in the central oscillator (the pineal gland) than in the peripheral structures, reflecting the synchronization of individual cells which is necessary for detection of the rhythm. The early development of the circadian system in birds reflects an absence of rhythmic maternal melatonin which in mammals synchronizes physiological processes of offspring. Developmental consequences of modified development of circadian system for its stability later in development are not known and should be studied.
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Affiliation(s)
- Michal Zeman
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
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26
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Falcón J, Migaud H, Muñoz-Cueto JA, Carrillo M. Current knowledge on the melatonin system in teleost fish. Gen Comp Endocrinol 2010; 165:469-82. [PMID: 19409900 DOI: 10.1016/j.ygcen.2009.04.026] [Citation(s) in RCA: 269] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 04/15/2009] [Accepted: 04/23/2009] [Indexed: 01/27/2023]
Abstract
Melatonin is a much conserved feature in vertebrates that plays a central role in the entrainment of daily and annual physiological rhythms. Investigations aiming at understanding how melatonin mediates the effects of photoperiod on crucial functions and behaviors have been very active in the last decades, particularly in mammals. In fish a clear-cut picture is still missing. Here we review the available data on (i) the sites of melatonin production in fish, (ii) the mechanisms that control its daily and annual rhythms of production and (iii) the characterization of its different receptor subtypes, their location and regulation. The in vivo and in vitro data on melatonin effects on crucial neuroendocrine regulations, including reproduction, growth, feeding and behavioral responses, are also reviewed. Finally we discuss how manipulation of the photic cues impact on fish circannual clock and annual cycle of reproduction, and how this can be used for aquaculture purposes.
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Affiliation(s)
- J Falcón
- CNRS, FRE3247 et GDR2821, Modèles en Biologie cellulaire et évolutive, Avenue Fontaulé, BP 44, F-66651 Banyuls-sur-Mer, Cedex, France.
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27
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Dufour S, Sebert ME, Weltzien FA, Rousseau K, Pasqualini C. Neuroendocrine control by dopamine of teleost reproduction. JOURNAL OF FISH BIOLOGY 2010; 76:129-160. [PMID: 20738703 DOI: 10.1111/j.1095-8649.2009.02499.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
While gonadotropin-releasing hormone (GnRH) is considered as the major hypothalamic factor controlling pituitary gonadotrophins in mammals and most other vertebrates, its stimulatory actions may be opposed by the potent inhibitory actions of dopamine (DA) in teleosts. This dual neuroendocrine control of reproduction by GnRH and DA has been demonstrated in various, but not all, adult teleosts, where DA participates in an inhibitory role in the neuroendocrine regulation of the last steps of gametogenesis (final oocyte maturation and ovulation in females and spermiation in males). This has major implications for inducing spawning in aquaculture. In addition, DA may also play an inhibitory role during the early steps of gametogenesis in some teleost species, and thus interact with GnRH in the control of puberty. Various neuroanatomical investigations have shown that DA neurones responsible for the inhibitory control of reproduction originate in a specific nucleus of the preoptic area (NPOav) and project directly to the region of the pituitary where gonadotrophic cells are located. Pharmacological studies showed that the inhibitory effects of DA on pituitary gonadotrophin production are mediated by DA-D2 type receptors. DA-D2 receptors have now been sequenced in several teleosts, and the coexistence of several DA-D2 subtypes has been demonstrated in a few species. Hypophysiotropic DA activity varies with development and reproductive cycle and probably is controlled by environmental cues as well as endogenous signals. Sex steroids have been shown to regulate dopaminergic systems in several teleost species, affecting both DA synthesis and DA-D2 receptor expression. This demonstrates that sex steroid feedbacks target DA hypophysiotropic system, as well as the other components of the brain-pituitary gonadotrophic axis, GnRH and gonadotrophins. Recent studies have revealed that melatonin modulates the activity of DA systems in some teleosts, making the melatonin-DA pathway a prominent relay between environmental cues and control of reproduction. The recruitment of DA neurons for the neuroendocrine control of reproduction provides an additional brain pathway for the integration of various internal and environmental cues. The plasticity of the DA neuroendocrine role observed in teleosts may have contributed to their large diversity of reproductive cycles.
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Affiliation(s)
- S Dufour
- Muséum National d'Histoire Naturelle, UMR Biologie des Organismes et Ecosystèmes Aquatiques" MNHN-CNRS-IRD-UPMC, 7 rue Cuvier, CP 32, 75231 Paris Cedex 05, France.
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Migaud H, Davie A, Taylor JF. Current knowledge on the photoneuroendocrine regulation of reproduction in temperate fish species. JOURNAL OF FISH BIOLOGY 2010; 76:27-68. [PMID: 20738699 DOI: 10.1111/j.1095-8649.2009.02500.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Seasonality is an important adaptive trait in temperate fish species as it entrains or regulates most physiological events such as reproductive cycle, growth profile, locomotor activity and key life-stage transitions. Photoperiod is undoubtedly one of the most predictable environmental signals that can be used by most living organisms including fishes in temperate areas. This said, however, understanding of how such a simple signal can dictate the time of gonadal recruitment and spawning, for example, is a complex task. Over the past few decades, many scientists attempted to unravel the roots of photoperiodic signalling in teleosts by investigating the role of melatonin in reproduction, but without great success. In fact, the hormone melatonin is recognized as the biological time-keeping hormone in fishes mainly due to the fact that it reflects the seasonal variation in daylength across the whole animal kingdom rather than the existence of direct evidences of its role in the entrainment of reproduction in fishes. Recently, however, some new studies clearly suggested that melatonin interacts with the reproductive cascade at a number of key steps such as through the dopaminergic system in the brain or the synchronization of the final oocyte maturation in the gonad. Interestingly, in the past few years, additional pathways have become apparent in the search for a fish photoneuroendocrine system including the clock-gene network and kisspeptin signalling and although research on these topics are still in their infancy, it is moving at great pace. This review thus aims to bring together the current knowledge on the photic control of reproduction mainly focusing on seasonal temperate fish species and shape the current working hypotheses supported by recent findings obtained in teleosts or based on knowledge gathered in mammalian and avian species. Four of the main potential regulatory systems (light perception, melatonin, clock genes and kisspeptin) in fish reproduction are reviewed.
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Affiliation(s)
- H Migaud
- Reproduction and Genetics Group, Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK.
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Martinez‐Chavez CC, Al‐Khamees S, Campos‐Mendoza A, Penman DJ, Migaud H. Clock‐Controlled Endogenous Melatonin Rhythms in Nile Tilapia (Oreochromis niloticus niloticus) and African Catfish (Clarias gariepinus). Chronobiol Int 2009; 25:31-49. [DOI: 10.1080/07420520801917547] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Martinez-Chavez C, Migaud H. Retinal light input is required to sustain plasma melatonin rhythms in Nile tilapia Oreochromis niloticus niloticus. Brain Res 2009; 1269:61-7. [DOI: 10.1016/j.brainres.2009.03.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Revised: 03/10/2009] [Accepted: 03/10/2009] [Indexed: 11/29/2022]
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Nikaido Y, Ueda S, Takemura A. Photic and circadian regulation of melatonin production in the Mozambique tilapia Oreochromis mossambicus. Comp Biochem Physiol A Mol Integr Physiol 2009; 152:77-82. [DOI: 10.1016/j.cbpa.2008.09.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Revised: 09/02/2008] [Accepted: 09/02/2008] [Indexed: 10/21/2022]
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Sébert ME, Legros C, Weltzien FA, Malpaux B, Chemineau P, Dufour S. Melatonin activates brain dopaminergic systems in the eel with an inhibitory impact on reproductive function. J Neuroendocrinol 2008; 20:917-29. [PMID: 18445127 DOI: 10.1111/j.1365-2826.2008.01744.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In the eel, a deficit in gonadotrophin-releasing hormone (GnRH) and a strong dopaminergic (DA) inhibition are responsible for the blockade of gonad development if silver eels are prevented from their reproductive migration. Environmental factors that eels encounter during their oceanic reproductive migration are thought to play an important role in the stimulation of eel pubertal development. We investigated the potential role of melatonin, a known mediator of the effects of external factors on reproductive function in vertebrates. We demonstrated that a long-term melatonin treatment increased brain tyrosine hydroxylase (TH, the rate limiting enzyme of DA synthesis) mRNA expression in a region-dependent way. Melatonin stimulated the dopaminergic system of the preoptic area, which is involved in the inhibitory control of gonadotrophin [luteinising hormone (LH) and follicle-stimulating hormone (FSH)] synthesis and release. Moreover, we showed that the increased TH expression appeared to be consistent with melatonin binding site distribution as shown by 2[(125)I]-melatonin labelling studies. On the other hand, melatonin had no effects on the two eel native forms of GnRH (mGnRH and cGnRH-II) mRNA expression. Concerning the pituitary-gonad axis, we showed that melatonin treatment decreased both gonadotrophin beta-subunit (LHbeta, FSHbeta) mRNA expression and reduced sexual steroid (11-ketotestosterone, oestradiol) plasma levels. This indicates that melatonin treatment had a negative effect on eel reproductive function. To our knowledge, the results of the present study provide the first evidence that melatonin enhances TH expression in specific brain regions in a non-mammalian species. By this mechanism melatonin could represent one pathway by which environmental factors could modulate reproductive function in the eel.
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Affiliation(s)
- M-E Sébert
- USM 0401, UMR 5178 CNRS/MNHN/UPMC Biologie des Organismes Marins et Ecosystèmes, Département des Milieux et Peuplements Aquatiques, Muséum National d'Histoire Naturelle, Paris, France
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Yoshizawa M, Jeffery WR. Shadow response in the blind cavefish Astyanax reveals conservation of a functional pineal eye. ACTA ACUST UNITED AC 2008; 211:292-9. [PMID: 18203983 DOI: 10.1242/jeb.012864] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The blind cavefish Astyanax mexicanus undergoes bilateral eye degeneration during embryonic development. Despite the absence of light in the cave environment, cavefish have retained a structurally intact pineal eye. We show here that contrary to visual degeneration in the bilateral eyes, the cavefish pineal eye has conserved the ability to detect light. Larvae of two different Astyanax cavefish populations and the con-specific sighted surface-dwelling form (surface fish) respond similarly to light dimming by shading the pineal eye. As a response to shading, cavefish larvae swim upward vertically. This behavior resembles that of amphibian tadpoles rather than other teleost larvae, which react to shadows by swimming downward. The shadow response is highest at 1.5-days post-fertilization (d.p.f.), gradually diminishes, and is virtually undetectable by 7.5 d.p.f. The shadow response was substantially reduced after surgical removal of the pineal gland from surface fish or cavefish larvae, indicating that it is based on pineal function. In contrast, removal of one or both bilateral eye primordia did not affect the shadow response. Consistent with its light detecting capacity, immunocytochemical studies indicate that surface fish and cavefish pineal eyes express a rhodopsin-like antigen, which is undetectable in the degenerating bilateral eyes of cavefish larvae. We conclude that light detection by the pineal eye has been conserved in cavefish despite a million or more years of evolution in complete darkness.
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Affiliation(s)
- Masato Yoshizawa
- Department of Biology, University of Maryland, College Park, MD 20742, USA.
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Migaud H, Davie A, Martinez Chavez CC, Al-Khamees S. Evidence for differential photic regulation of pineal melatonin synthesis in teleosts. J Pineal Res 2007; 43:327-35. [PMID: 17910600 DOI: 10.1111/j.1600-079x.2007.00480.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aim of this study was to compare the circadian control of melatonin production in teleosts. To do so, the effects of ophthalmectomy on circulating melatonin rhythms were studied along with ex vivo pineal culture in six different teleosts. Results strongly suggested that the circadian control of melatonin production could have dramatically changed with at least three different systems being present in teleosts when one considers the photic regulation of pineal melatonin production. First, salmonids presented a decentralized system in which the pineal gland responds directly to light independently of the eyes. Then, in seabass and cod both the eyes and the pineal gland are required to sustain full night-time melatonin production. Finally, a third type of circadian control of melatonin production is proposed in tilapia and catfish in which the pineal gland would not be light sensitive (or only slightly) and required the eyes to perceive light and inhibit melatonin synthesis. Further studies (anatomical, ultrastructural, retinal projections) are needed to confirm these results. Ex vivo experiments indirectly confirmed these results, as while the pineal gland responded normally to day-night rhythms in salmonids, seabass and cod, only very low levels were obtained at night in tilapia and no melatonin could be measured from isolated pineal glands in catfish. Together, these findings suggest that mechanisms involved in the perception of light and the transduction of this signal through the circadian axis has changed in teleosts possibly as a reflection of the photic environment in which they have evolved in.
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Affiliation(s)
- H Migaud
- Reproduction and Genetics Group, Institute of Aquaculture, University of Stirling, Stirling, UK.
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Iigo M, Abe T, Kambayashi S, Oikawa K, Masuda T, Mizusawa K, Kitamura S, Azuma T, Takagi Y, Aida K, Yanagisawa T. Lack of circadian regulation of in vitro melatonin release from the pineal organ of salmonid teleosts. Gen Comp Endocrinol 2007; 154:91-7. [PMID: 17681505 DOI: 10.1016/j.ygcen.2007.06.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 06/08/2007] [Accepted: 06/13/2007] [Indexed: 11/29/2022]
Abstract
In many teleost species, the photoreceptive pineal organ harbors the circadian clock that regulates melatonin release in the pineal organ itself. However, the pineal organ of three salmonids (rainbow trout Oncorhynchus mykiss, masu salmon Oncorhynchus masou, and sockeye salmon Oncorhynchus nerka) did not exhibit circadian rhythms in melatonin release when maintained under constant darkness (DD) in vitro, suggesting that the pineal organs of all salmonids lack the circadian regulation of melatonin production. To test this hypothesis, the pineal organ of seven salmonids (common whitefish Coregonus lavaretus, grayling Thymallus thymallus, Japanese huchen Hucho perryi, Japanese charr Salvelius leucomaenis pluvius, brook trout Salvelius fontinalis, brown trout Salmo trutta and chum salmon Oncorhynchus keta) and closely related osmerids (ayu Plecoglossus altivelis altivelis and Japanese smelt Hypomesus nipponensis) were individually maintained in flow-through culture at 15 degrees C under several light conditions. Under light-dark cycles, the pineal organ of all species showed a rhythmic melatonin release with high rates during the dark phase. Under DD, the osmerid pineal organs exhibited circadian rhythms in melatonin release with high rates only during the subjective-night but the salmonid pineal organs constantly released melatonin at high rates. Under constant light, melatonin release was suppressed in all species. The pineal organ of rainbow trout maintained at different temperature (15, 20 or 25 degrees C) under DD released melatonin with high rates but the amount of melatonin released was temperature-sensitive (highest at 20 degrees C). Thus, melatonin release from the pineal organ of osmerids is regulated by both light and circadian clock but the circadian regulation is lacking in salmonids. These results indicate that ancestral salmonids lost the circadian regulation of melatonin production after the divergence from osmerid teleosts.
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Affiliation(s)
- Masayuki Iigo
- Department of Applied Biochemistry, Utsunomiya University, 350 Mine-machi, Utsunomiya, Tochigi 321-8505, Japan.
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Iigo M, Azuma T, Iwata M. Lack of Circadian Regulation of Melatonin Rhythms in the Sockeye Salmon (Oncorhynchus nerka)in vivoandin vitro. Zoolog Sci 2007; 24:67-70. [PMID: 17409718 DOI: 10.2108/zsj.24.67] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Melatonin profiles were determined in the plasma in vivo and in the pineal organ in vitro of the sockeye salmon (Oncorhynchus nerka) under various light conditions to test whether they are under circadian regulation. When serial blood samples were taken at 4-h intervals for 3 days via a cannula inserted into the dorsal aorta, plasma melatonin exhibited significant fluctuation under a light-dark cycle, with higher levels during the dark phase than during the light phase. No rhythmic fluctuations persisted under either constant dark or constant light, with constant low and high levels, respectively. Melatonin release from the pineal organ in flow-through culture exhibited a similar pattern in response to the change in light conditions, with high and low release associated with the dark and light phases, respectively. These results indicate that melatonin production in the sockeye salmon is driven by light and darkness but lacks circadian regulation.
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Affiliation(s)
- Masayuki Iigo
- Department of Applied Biochemistry, Faculty of Agriculture, Utsunomiya University, Tochigi, Japan.
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Firth BT, Belan I, Kennaway DJ. Persistence of a plasma melatonin rhythm in constant darkness and its inhibition by constant light in the sleepy lizard, Tiliqua rugosa. J Pineal Res 2006; 41:15-20. [PMID: 16842536 DOI: 10.1111/j.1600-079x.2006.00322.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study determined whether a blood plasma melatonin rhythm persists in constant photothermal environments in the sleepy lizard, Tiliqua rugosa. It builds upon an earlier investigation which provided equivocal results as to whether an in vivo melatonin rhythm persists in constant dark (DD) and light (LL) and temperature in this species. Using more frequent sampling points and new assay techniques, the present study showed that the melatonin rhythm persisted for at least 6 days at temperatures of 25 and 33 degrees C in constant dark (DD). The melatonin rhythm, however, was largely eliminated in constant light (LL) at 33 degrees C, thereby contradicting some previous findings in other species of reptiles where melatonin levels were apparently insensitive to an unexpected pulse of light at night. These results demonstrate that the sleepy lizard has a persistent, possibly circadian rhythm of melatonin in DD and constant temperature, and that the rhythm is inhibited by LL and constant temperature. Therefore, the sleepy lizard pineal gland may be an independent oscillator capable of driving the melatonin rhythm and be a transducer of the seasonally changing external photothermal environment.
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Affiliation(s)
- Bruce T Firth
- Department of Anatomical Sciences, University of Adelaide, Adelaide, Australia.
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Migaud H, Taylor JF, Taranger GL, Davie A, Cerdá-Reverter JM, Carrillo M, Hansen T, Bromage NR. A comparative ex vivo and in vivo study of day and night perception in teleosts species using the melatonin rhythm. J Pineal Res 2006; 41:42-52. [PMID: 16842540 DOI: 10.1111/j.1600-079x.2006.00330.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The purpose of this study was to determine and compare the light sensitivity of two commercially important, phylogenetically different teleost species in terms of melatonin production. Three series of experiments were performed on both Atlantic salmon and European sea bass. First, a range of light intensities were tested ex vivo on pineal melatonin production in culture during the dark phase. Then, light transmission through the skull was investigated, and finally short-term in vivo light sensitivity trials were performed. Results showed that sea bass pineal gland ex vivo are at least 10 times more sensitive to light than that of the salmon. Light intensity threshold in sea bass appeared to be between 3.8 x 10(-5) and 3.8 x 10(-6) W/m2 in contrast to 3.8 x 10(-4) and 3.8 x 10(-5) W/m2 in salmon. These highlighted species-specific light sensitivities of pineal melatonin production that are likely to be the result of adaptation to particular photic niches. Light transmission results showed that a significantly higher percentage of light penetrates the sea bass pineal window relative to salmon, and confirmed that penetration is directly related to wavelength with higher penetration towards the red end of the visible spectrum. Although results obtained in vivo were comparable, large differences between ex vivo and in vivo were observed in both species. The pineal gland in isolation thus appeared to have different sensitivities as the whole animal, suggesting that retinal and/or deep brain photoreception may contribute, in vivo, to the control of melatonin production.
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Affiliation(s)
- H Migaud
- Reproduction and Genetics group, Institute of Aquaculture, University of Stirling, Stirling, UK.
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Takemura A, Ueda S, Hiyakawa N, Nikaido Y. A direct influence of moonlight intensity on changes in melatonin production by cultured pineal glands of the golden rabbitfish, Siganus guttatus. J Pineal Res 2006; 40:236-41. [PMID: 16499560 DOI: 10.1111/j.1600-079x.2005.00306.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Rabbitfish are a restricted lunar-synchronized spawner that spawns around a species-specific lunar phase. It is not known how the fish perceive changes in cues from the moon. One possible explanation is that rabbitfish utilize changes in moonlight intensity to establish synchrony. The purpose of the present study was to examine whether or not the pineal gland of the golden rabbitfish can directly perceive changes in moonlight intensity. Isolated pineal glands were statically cultured under natural or artificial light conditions and melatonin secreted into the culture medium was measured using a time-resolved fluoroimmunoassay. Under an artificial light/dark cycle, melatonin secretion significantly increased during the dark phase. Under continuous light conditions, melatonin secretion was suppressed, while culture under continuous dark conditions seemed to duplicate melatonin secretion corresponding to the light/dark cycle in which the fish were acclimated. When cultured pineal glands were kept under natural light conditions on the dates of the full and the new moon, small amounts of melatonin were secreted at night. Moreover, exposure of cultured pineal glands to artificial and natural light conditions resulted in a significant decrease of melatonin secretion within 2 hr. These results suggest that the isolated pineal gland of golden rabbitfish responds to environmental light cycles and that 'brightness' of the night moon has an influence on melatonin secretion from the isolated pineal gland.
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Affiliation(s)
- Akihiro Takemura
- Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Motobu, Okinawa, Japan.
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40
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Molecular and Cellular Regulation of Pineal Organ Responses. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/s1546-5098(06)25006-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Iigo M, Ikeda E, Sato M, Kawasaki S, Noguchi F, Nishi G. Circadian rhythms of ocular melatonin in the wrasse Halichoeres tenuispinnis, a labrid teleost. Gen Comp Endocrinol 2006; 145:32-8. [PMID: 16112672 DOI: 10.1016/j.ygcen.2005.06.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2005] [Revised: 06/27/2005] [Accepted: 06/29/2005] [Indexed: 11/22/2022]
Abstract
Using in vivo and in vitro methods we studied the regulation of ocular melatonin rhythms in the wrasse Halichoeres tenuispinnis, by either light or the circadian clock. Rhythmic changes in ocular melatonin levels under light-dark (LD) cycles were persistent under constant darkness (DD), and had a circadian periodicity of approximately 24h. However, ocular melatonin levels remained low under constant light conditions. When wrasse were exposed to a single 6-h light pulse at three different circadian phases under DD, phase-dependent phase shifts in the circadian rhythms of ocular melatonin were observed. When eyecups were prepared during mid-light periods or at the onset of darkness, and incubated in vitro in either light or dark periods, both time and light conditions affected melatonin release. These results indicate that the melatonin rhythms in the wrasse eye are driven by an ocular circadian clock that is entrained to LD cycles via local photoreceptors.
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Affiliation(s)
- Masayuki Iigo
- Department of Applied Biochemistry, Faculty of Agriculture, Utsunomiya University, 350 Mine-machi, Utsunomiya, Tochigi 321-8505, Japan.
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Ceinos RM, Rábade S, Soengas JL, Míguez JM. Indoleamines and 5-methoxyindoles in trout pineal organ in vivo: daily changes and influence of photoperiod. Gen Comp Endocrinol 2005; 144:67-77. [PMID: 15950974 DOI: 10.1016/j.ygcen.2005.04.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2004] [Revised: 04/15/2005] [Accepted: 04/25/2005] [Indexed: 10/25/2022]
Abstract
This study describes the diel rhythms in several indoleamines, melatonin, and related 5-methoxyindoles in the pineal organ of rainbow trout in vivo. In addition, the effect of different photoperiod conditions was evaluated. Melatonin levels displayed clear daily rhythms in the pineal organ of rainbow trout kept experimentally under long (LD 16:08), neutral (LD 12:12), and short (LD 08:16) photoperiods. Duration of melatonin signal was dependent on the night length of prevailing photoperiod, while peak amplitude was higher when lengthening the photoperiod. Significant daily rhythms in 5-HT content, the precursor of melatonin synthesis, were found in neutral and short photoperiod with increases of the amine content just after the light-dark interphase and decreases in the middle of the night, which were more important under short photoperiod. In contrast, no significant 24-h cyclic variation was found in pineal 5-HT content under long photoperiod. Daily profiles in the content of the main 5-HT oxidative metabolite, the 5-hydroxyindoleacetic acid (5-HIAA), outlined those of the amine precursor. The chronograms of both aminergic compounds contrast with those of 5-hydroxytryptophan content, which displayed a net tendency to increase at night. This study also provides evidence for the existence of daily cyclic changes in the content of 5-methoxytryptamine (5-MT), 5-methoxyindoleacetic acid (5-MIAA), and 5-methoxytryptophol (5-MTOL) in trout pineal organ, which were also dependent on photoperiod. The 24-h profiles in 5-MT content correlated well with those of 5-HT, showing a peak at the first hour of darkness in all photoperiodic conditions, and a decay at midnight only in both neutral and long photoperiods. Similarly, the content of 5-MTOL also displayed high values during the day-night transition in trout kept under neutral and long photoperiods, followed by a slow decay all along the night. Finally, levels of 5-MIAA increased in all photoperiods when lights were turned off, being this nocturnal increase maximal in fish kept under LD 16:08. These results suggest that light-dark cycle modulates daily rhythms in pineal indoles and non-melatonin 5-methoxyindoles by acting mainly through the melatonin synthesis activity, which limits the availability of 5-HT for the oxidative and direct methylation pathways. In addition, it seems that a nocturnally increased synthesis of 5-HT might be a requirement for the optimal formation of melatonin and other 5-methoxyindoles in the pineal organ when trout remain under short photoperiods.
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Affiliation(s)
- Rosa M Ceinos
- Laboratorio de Fisiología Animal, Departamento Biología Funcional y CC Salud, Facultad de Biología, Universidad de Vigo, 36200 Vigo, Spain
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Forlano PM, Deitcher DL, Bass AH. Distribution of estrogen receptor alpha mRNA in the brain and inner ear of a vocal fish with comparisons to sites of aromatase expression. J Comp Neurol 2005; 483:91-113. [PMID: 15672394 DOI: 10.1002/cne.20397] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Among vertebrates, teleost fish have the greatest capacity for estrogen production in the brain. Previously, we characterized the distribution of the estrogen-synthesizing enzyme aromatase in the brain of the midshipman fish. Here, we investigated the distribution of estrogen receptor alpha (ERalpha). A partial cDNA of ERalpha was cloned and used to generate midshipman-specific primers for RT and real-time PCR which identified transcripts in liver and ovary, the CNS, and the sensory epithelium of the main auditory endorgan (sacculus). In situ hybridization revealed abundant expression throughout the preoptic area, a vocal-acoustic site in the hypothalamus, amygdala homologs of the dorsal pallium, the pineal organ, the inner ear, the pituitary, and the ovary. Weaker expression was found in the midbrain's nucleus of the medial longitudinal fasciculus and in the dimorphic vocal motor nucleus. ERalpha expression in the pineal, gonad, and pituitary axis may function to time seasonal abiotic cues to reproductive state, while expression in the vocal motor and auditory systems support neurophysiological evidence for estrogen as a modulator of vocal motor and auditory encoding mechanisms in midshipman fish. While ERalpha is restricted to specific nuclei, aromatase expression is abundant in glial cells throughout the entire forebrain, and high in midbrain and hindbrain - spinal vocal regions. The only site of aromatase-containing neurons is in the peripheral auditory system, where it is localized to ganglion cells in the auditory nerve. Estrogen production proximal to ERalpha-positive neurons may provide for focal sites of estrogen effects on reproductive-, vocal-, and auditory-related neurons.
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Affiliation(s)
- Paul M Forlano
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853, USA
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Sokołowska E, Kalamarz H, Kulczykowska E. Seasonal changes in brain melatonin concentration in the three-spined stickleback (Gasterosteus aculeatus): towards an endocrine calendar. Comp Biochem Physiol A Mol Integr Physiol 2004; 139:365-9. [PMID: 15556393 DOI: 10.1016/j.cbpb.2004.10.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Revised: 10/01/2004] [Accepted: 10/02/2004] [Indexed: 11/21/2022]
Abstract
Pineal organ and its hormone melatonin (N-acetyl-5-methoxytryptamine) is likely involved in timing and synchronisation of many internal processes, such as reproduction, with annual changes in environmental cues, i.e., photoperiod and water temperature. The seasonal changes in melatonin profile in stickleback brains related to the following reproductive phases were examined, and the link between melatonin concentrations and the stages of spawning cycle was analysed. Two wild populations of sticklebacks were exposed to annual environmental changes in their natural habitats. Brains, gonads, kidneys and livers were collected over 2 years. Melatonin was measured using RIA and the indices, gonadosomatic (GSI), nephrosomatic (NSI) and hepatosomatic (HSI), were calculated. The role of melatonin, as a component of internal calendar engaged in the control of seasonal breeding in this species, is discussed. The extremely high melatonin levels observed in early spring (March) and autumn (October) seem to mark out a time frame for spawning in sticklebacks. The seasonal pattern of melatonin production and identified development stages of gonads suggests the potential inhibitory effect of the hormone on stickleback reproduction in shortening photoperiod and stimulatory effect in lengthening photoperiod.
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Affiliation(s)
- Ewa Sokołowska
- Department of Genetics and Marine Biotechnology, Institute of Oceanology of Polish Academy of Sciences, św. Wojciecha 5 Str., 81-347 Gdynia, Poland
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Takemura A, Susilo ES, Rahman MDS, Morita M. Perception and possible utilization of moonlight intensity for reproductive activities in a lunar-synchronized spawner, the golden rabbitfish. ACTA ACUST UNITED AC 2004; 301:844-51. [PMID: 15449345 DOI: 10.1002/jez.a.105] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Rabbitfishes are known to spawn synchronously around the species-specific lunar phase. It is considered that they perceive and utilize cues from the moon in order to be synchronized gonadal development and spawning with the lunar cycle. Using the golden rabbitfish, Siganus guttatus, which spawns synchronously around the first quarter moon during the reproductive season, we measured the fluctuation of melatonin levels and examined the response of the fish to moonlight intensity. Daily fluctuation of melatonin concentration in the blood of golden rabbitfish showed low levels during daytime and high levels during night-time, suggesting that melatonin functions in the perception and utilization of photoperiod. Plasma melatonin concentration at the new moon was higher than that at the full moon. When the fish were exposed to moonlight at midnight of the both moon phases, the melatonin concentrations decreased to the control levels. These results show that the fish possibly perceive moonlight intensity and plasma melatonin fluctuates according to 'lightness' at a point of night. At the first spawning period (experiment was started one month before the spawning), the fish reared under natural conditions spawned at the expected spawning dates, whereas the fish reared under the constant darkness and lightness of night did not spawn. At the second spawning period (experiment was started 2 weeks before the spawning), the fish reared under the conditions of natural and constant darkness of night spawned but not that of constant lightness of night. It is possible that night conditions are related to synchronous gonadal development and spawning in the golden rabbitfish.
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Affiliation(s)
- Akihiro Takemura
- Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, 3422 Sesoko, Motobu, Okinawa 905-0227, Japan.
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Iigo M, Fujimoto Y, Gunji-Suzuki M, Yokosuka M, Hara M, Ohtani-Kaneko R, Tabata M, Aida K, Hirata K. Circadian rhythm of melatonin release from the photoreceptive pineal organ of a teleost, ayu (Plecoglossus altivelis) in flow-thorough culture. J Neuroendocrinol 2004; 16:45-51. [PMID: 14962075 DOI: 10.1111/j.1365-2826.2004.01132.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In the present study, we tested whether the pineal organ of ayu (Plecoglossus altivelis), an osmerid teleost close relative of salmonids, harbours a circadian oscillator regulating rhythmic melatonin release using flow-through culture. The pineal organ maintained under light/dark cycles released melatonin in a rhythmic fashion with high levels during the dark phase. A circadian rhythm of melatonin release persisted in constant darkness for at least four cycles. Characteristics of the circadian rhythm (free-running period, phase and amplitude) exhibited small variations among cultures when the data was normalized, indicating that this system is sufficient for the analysis of the circadian rhythm both at qualitative and quantitative levels. Six-hour extension of the light phase from the normal onset time of the dark phase or exposure to constant light for 36 or 48 h before transfer to constant darkness significantly inhibited melatonin release. Phase shifts in the circadian rhythm of melatonin release were also observed. Thus, the ayu pineal organ contains all the three essential components of the circadian system (a circadian clock, the photoreceptor responsible for photic entrainment of the clock, and melatonin generating system as an output pathway). This system should provide a useful model for analysing the physiological and molecular basis of the vertebrate circadian system. In addition, further comparative studies using salmonids and related species including ayu will provide some insight into the evolution of the roles of the pineal organ in the vertebrate circadian system.
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Affiliation(s)
- M Iigo
- Department of Anatomy, St. Marianna University School of Medicine, Miyamae, Kawasaki, Japan.
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Iigo M, Sato M, Ikeda E, Kawasaki S, Noguchi F, Nishi G. Effects of photic environment on ocular melatonin contents in a labrid teleost, the wrasse Halichoeres tenuispinnis. Gen Comp Endocrinol 2003; 133:252-9. [PMID: 12928014 DOI: 10.1016/s0016-6480(03)00168-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The wrasse Halichoeres tenuispinnis is a labrid teleost that exhibits robust circadian rhythms in locomotor activity under constant light (LL). This fish buries itself in the bottom sand during the subjective-night, thereby suggesting that behaviorally it adjusts its circadian clock to avoid photoreception. In this study, we determined ocular melatonin contents of the wrasse under various photic environments and used ocular melatonin to indicate photoreception. Under light-dark (LD) cycles, ocular melatonin contents of the wrasse exhibited a daily rhythm, with higher levels during the dark phase than those during the light phase. The duration of nocturnal melatonin elevation was longer under LD 9:15 than under LD 15:9. Acute exposure to 2-h light during the dark phase resulted in a significant decrease in ocular melatonin at mid-dark in an intensity-dependent manner. However, acute exposure to different intensities of light for 2h during the light phase had only a small effect on ocular melatonin contents at mid-day. Under LL, ocular melatonin contents in the wrasse reared with bottom sand present exhibited circadian rhythms and were significantly higher than those with transluscent acryl pellets on the bottom. These results indicate that the ocular melatonin rhythm in the wrasse is driven both by the photic environment and by a circadian clock, and that the wrasse that buries itself in the bottom sand can perceive low intensity of light.
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Affiliation(s)
- Masayuki Iigo
- Department of Anatomy, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kawasaki 216-8511, Japan.
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Gupta BBP, Premabati Y. Differential effects of melatonin on plasma levels of thyroxine and triiodothyronine levels in the air-breathing fish, Clarias gariepinus, during breeding and quiescent periods. Gen Comp Endocrinol 2002; 129:146-51. [PMID: 12460598 DOI: 10.1016/s0016-6480(02)00527-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Effects of morning and evening injections of three doses of melatonin were studied on the plasma levels of thyroxine (T(4)) and triiodothyronine (T(3)) in an air-breathing fish Clarias gariepinus during its quiescent phase and breeding phase. Depending on seasons and time of administration, melatonin increased, decreased or had no effects on the plasma levels of T(4) and T(3). Present findings strongly suggest that melatonin is involved in the regulation of thyroid hormones in C. gariepinus, and differentially influences T(4) and T(3) level.
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Affiliation(s)
- B B P Gupta
- Department of Zoology, Environmental Endocrinology Laboratory, North-Eastern Hill University, Shillong 793 022, India.
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Rensing L, Ruoff P. Temperature effect on entrainment, phase shifting, and amplitude of circadian clocks and its molecular bases. Chronobiol Int 2002; 19:807-64. [PMID: 12405549 DOI: 10.1081/cbi-120014569] [Citation(s) in RCA: 195] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Effects of temperature and temperature changes on circadian clocks in cyanobacteria, unicellular algae, and plants, as well as fungi, arthropods, and vertebrates are reviewed. Periodic temperature with periods around 24 h even in the low range of 1-2 degrees C (strong Zeitgeber effect) can entrain all ectothermic (poikilothermic) organisms. This is also reflected by the phase shifts-recorded by phase response curves (PRCs)-that are elicited by step- or pulsewise changes in the temperature. The amount of phase shift (weak or strong type of PRC) depends on the amplitude of the temperature change and on its duration when applied as a pulse. Form and position of the PRC to temperature pulses are similar to those of the PRC to light pulses. A combined high/low temperature and light/dark cycle leads to a stabile phase and maximal amplitude of the circadian rhythm-when applied in phase (i.e., warm/light and cold/dark). When the two Zeitgeber cycles are phase-shifted against each other the phase of the circadian rhythm is determined by either Zeitgeber or by both, depending on the relative strength (amplitude) of both Zeitgeber signals and the sensitivity of the species/individual toward them. A phase jump of the circadian rhythm has been observed in several organisms at a certain phase relationship of the two Zeitgeber cycles. Ectothermic organisms show inter- and intraspecies plus seasonal variations in the temperature limits for the expression of the clock, either of the basic molecular mechanism, and/or the dependent variables. A step-down from higher temperatures or a step-up from lower temperatures to moderate temperatures often results in initiation of oscillations from phase positions that are about 180 degrees different. This may be explained by holding the clock at different phase positions (maximum or minimum of a clock component) or by significantly different levels of clock components at the higher or lower temperatures. Different permissive temperatures result in different circadian amplitudes, that usually show a species-specific optimum. In endothermic (homeothermic) organisms periodic temperature changes of about 24 h often cause entrainment, although with considerable individual differences, only if they are of rather high amplitudes (weak Zeitgeber effects). The same applies to the phase-shifting effects of temperature pulses. Isolated bird pineals and rat suprachiasmatic nuclei tissues on the other hand, respond to medium high temperature pulses and reveal PRCs similar to that of light signals. Therefore, one may speculate that the self-selected circadian rhythm of body temperature in reptiles or the endogenously controlled body temperature in homeotherms (some of which show temperature differences of more than 2 degrees C) may, in itself, serve as an internal entraining system. The so-called heterothermic mammals (undergoing low body temperature states in a daily or seasonal pattern) may be more sensitive to temperature changes. Effects of temperature elevation on the molecular clock mechanisms have been shown in Neurospora (induction of the frequency (FRQ) protein) and in Drosophila (degradation of the period (PER) and timeless (TIM) protein) and can explain observed phase shifts of rhythms in conidiation and locomotor activity, respectively. Temperature changes probably act directly on all processes of the clock mechanism some being more sensitive than the others. Temperature changes affect membrane properties, ion homeostasis, calcium influx, and other signal cascades (cAMP, cGMP, and the protein kinases A and C) (indirect effects) and may thus influence, in particular, protein phosphorylation processes of the clock mechanism. The temperature effects resemble to some degree those induced by light or by light-transducing neurons and their transmitters. In ectothermic vertebrates temperature changes significantly affect the melatonin rhythm, which in turn exerts entraining (phase shifting) functions.
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Affiliation(s)
- Ludger Rensing
- Institute of Cell Biology, Biochemistry and Biotechnology, University of Bremen, Germany.
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