Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/19667
Appears in Collections:Aquaculture Journal Articles
Peer Review Status: Refereed
Title: Influence of light intensity on plasma melatonin and locomotor activity rhythms in tench
Authors: Vera, LM
Lopez-Olmeda, Jose F
Bayarri, Maria Jose
Madrid, Juan Antonio
Sanchez-Vazquez, F Javier
Contact Email: luisa.veraandujar@stir.ac.uk
Keywords: Tinca tinca
light intensity
melatonin
locomotor activity
light pulse
circadian rhythm
Issue Date: 2005
Publisher: Informa Healthcare
Citation: Vera L, Lopez-Olmeda JF, Bayarri MJ, Madrid JA & Sanchez-Vazquez FJ (2005) Influence of light intensity on plasma melatonin and locomotor activity rhythms in tench, Chronobiology International, 22 (1), pp. 67-78.
Abstract: Melatonin production by the pineal organ is influenced by light intensity, as has been described in most vertebrate species, in which melatonin is considered a synchronizer of circadian rhythms. In tench, strict nocturnal activity rhythms have been described, although the role of melatonin has not been clarified. In this study we investigated daily activity and melatonin rhythms under 1212 light‐dark (LD) conditions with two different light intensities (58.6 and 1,091 µW/cm2), and the effect of 1 h broad spectrum white light pulses of different intensities (3.3, 5.3, 10.5, 1,091.4 µW/cm2) applied at middarkness (MD) on nocturnal circulating melatonin. The results showed that plasma melatonin in tench under LD 1212 and high light conditions displayed rhythmic variation, where values at MD (255.8±65.9 pg/ml) were higher than at midlight (ML) (70.7±31.9 pg/ml). Such a difference between MD and ML values was reduced in animals exposed to LD 1212 and low light intensity. The application of 1 h light pulses at MD lowered plasma melatonin to 111.6±3.2 pg/ml (in the 3.3-10.5 µW/cm2 range) and to 61.8±18.3 pg/ml (with the 1,091.4 µW/cm2 light pulse) and totally suppressed nocturnal locomotor activity. These results show that melatonin rhythms persisted in tench exposed to low light intensity although the amplitude of the rhythm is affected. In addition, it was observed that light pulses applied at MD affected plasma melatonin content and locomotor activity. Such a low threshold suggests that the melatonin system is capable of transducing light even under dim conditions, which may be used by this nocturnal fish to synchronize to weak night light signals (e.g., moonlight cycles).Read More: http://informahealthcare.com/doi/abs/10.1081/CBI-200038157
Type: Journal Article
URI: http://hdl.handle.net/1893/19667
DOI Link: http://dx.doi.org/10.1081/CBI-200038157
Rights: The publisher does not allow this work to be made publicly available in this Repository. Please use the Request a Copy feature at the foot of the Repository record to request a copy directly from the author. You can only request a copy if you wish to use this work for your own research or private study.
Affiliation: Aquaculture
University of Murcia
University of Murcia
University of Murcia
University of Murcia

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